qemu-options.hx

HXCOMM Use DEFHEADING() to define headings in both help text and texi
HXCOMM Text between STEXI and ETEXI are copied to texi version and
HXCOMM discarded from C version
HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to
HXCOMM construct option structures, enums and help message for specified
HXCOMM architectures.
HXCOMM HXCOMM can be used for comments, discarded from both texi and C

DEFHEADING(Standard options:)
STEXI
@table @option
ETEXI

DEF("help", 0, QEMU_OPTION_h,
    "-h or -help     display this help and exit\n", QEMU_ARCH_ALL)
STEXI
@item -h
@findex -h
Display help and exit
ETEXI
SRST
``-h``
    Display help and exit
ERST

DEF("version", 0, QEMU_OPTION_version,
    "-version        display version information and exit\n", QEMU_ARCH_ALL)
STEXI
@item -version
@findex -version
Display version information and exit
ETEXI
SRST
``-version``
    Display version information and exit
ERST

DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
    "-machine [type=]name[,prop[=value][,...]]\n"
    "                selects emulated machine ('-machine help' for list)\n"
    "                property accel=accel1[:accel2[:...]] selects accelerator\n"
    "                supported accelerators are kvm, xen, hax, hvf, whpx or tcg (default: tcg)\n"
    "                vmport=on|off|auto controls emulation of vmport (default: auto)\n"
    "                dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
    "                mem-merge=on|off controls memory merge support (default: on)\n"
    "                aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
    "                dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
    "                suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
    "                nvdimm=on|off controls NVDIMM support (default=off)\n"
    "                enforce-config-section=on|off enforce configuration section migration (default=off)\n"
    "                memory-encryption=@var{} memory encryption object to use (default=none)\n"
    "                hmat=on|off controls ACPI HMAT support (default=off)\n",
    QEMU_ARCH_ALL)
STEXI
@item -machine [type=]@var{name}[,prop=@var{value}[,...]]
@findex -machine
Select the emulated machine by @var{name}. Use @code{-machine help} to list
available machines.

For architectures which aim to support live migration compatibility
across releases, each release will introduce a new versioned machine
type. For example, the 2.8.0 release introduced machine types
``pc-i440fx-2.8'' and ``pc-q35-2.8'' for the x86_64/i686 architectures.

To allow live migration of guests from QEMU version 2.8.0, to QEMU
version 2.9.0, the 2.9.0 version must support the ``pc-i440fx-2.8''
and ``pc-q35-2.8'' machines too. To allow users live migrating VMs
to skip multiple intermediate releases when upgrading, new releases
of QEMU will support machine types from many previous versions.

Supported machine properties are:
@table @option
@item accel=@var{accels1}[:@var{accels2}[:...]]
This is used to enable an accelerator. Depending on the target architecture,
kvm, xen, hax, hvf, whpx or tcg can be available. By default, tcg is used. If there is
more than one accelerator specified, the next one is used if the previous one
fails to initialize.
@item vmport=on|off|auto
Enables emulation of VMWare IO port, for vmmouse etc. auto says to select the
value based on accel. For accel=xen the default is off otherwise the default
is on.
@item dump-guest-core=on|off
Include guest memory in a core dump. The default is on.
@item mem-merge=on|off
Enables or disables memory merge support. This feature, when supported by
the host, de-duplicates identical memory pages among VMs instances
(enabled by default).
@item aes-key-wrap=on|off
Enables or disables AES key wrapping support on s390-ccw hosts. This feature
controls whether AES wrapping keys will be created to allow
execution of AES cryptographic functions.  The default is on.
@item dea-key-wrap=on|off
Enables or disables DEA key wrapping support on s390-ccw hosts. This feature
controls whether DEA wrapping keys will be created to allow
execution of DEA cryptographic functions.  The default is on.
@item nvdimm=on|off
Enables or disables NVDIMM support. The default is off.
@item enforce-config-section=on|off
If @option{enforce-config-section} is set to @var{on}, force migration
code to send configuration section even if the machine-type sets the
@option{migration.send-configuration} property to @var{off}.
NOTE: this parameter is deprecated. Please use @option{-global}
@option{migration.send-configuration}=@var{on|off} instead.
@item memory-encryption=@var{}
Memory encryption object to use. The default is none.
@item hmat=on|off
Enables or disables ACPI Heterogeneous Memory Attribute Table (HMAT) support.
The default is off.
@end table
ETEXI
SRST
``-machine [type=]name[,prop=value[,...]]``
    Select the emulated machine by name. Use ``-machine help`` to list
    available machines.

    For architectures which aim to support live migration compatibility
    across releases, each release will introduce a new versioned machine
    type. For example, the 2.8.0 release introduced machine types
    "pc-i440fx-2.8" and "pc-q35-2.8" for the x86\_64/i686 architectures.

    To allow live migration of guests from QEMU version 2.8.0, to QEMU
    version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8"
    and "pc-q35-2.8" machines too. To allow users live migrating VMs to
    skip multiple intermediate releases when upgrading, new releases of
    QEMU will support machine types from many previous versions.

    Supported machine properties are:

    ``accel=accels1[:accels2[:...]]``
        This is used to enable an accelerator. Depending on the target
        architecture, kvm, xen, hax, hvf, whpx or tcg can be available.
        By default, tcg is used. If there is more than one accelerator
        specified, the next one is used if the previous one fails to
        initialize.

    ``vmport=on|off|auto``
        Enables emulation of VMWare IO port, for vmmouse etc. auto says
        to select the value based on accel. For accel=xen the default is
        off otherwise the default is on.

    ``dump-guest-core=on|off``
        Include guest memory in a core dump. The default is on.

    ``mem-merge=on|off``
        Enables or disables memory merge support. This feature, when
        supported by the host, de-duplicates identical memory pages
        among VMs instances (enabled by default).

    ``aes-key-wrap=on|off``
        Enables or disables AES key wrapping support on s390-ccw hosts.
        This feature controls whether AES wrapping keys will be created
        to allow execution of AES cryptographic functions. The default
        is on.

    ``dea-key-wrap=on|off``
        Enables or disables DEA key wrapping support on s390-ccw hosts.
        This feature controls whether DEA wrapping keys will be created
        to allow execution of DEA cryptographic functions. The default
        is on.

    ``nvdimm=on|off``
        Enables or disables NVDIMM support. The default is off.

    ``enforce-config-section=on|off``
        If ``enforce-config-section`` is set to on, force migration code
        to send configuration section even if the machine-type sets the
        ``migration.send-configuration`` property to off. NOTE: this
        parameter is deprecated. Please use ``-global``
        ``migration.send-configuration``\ =on\|off instead.

    ``memory-encryption=``
        Memory encryption object to use. The default is none.

    ``hmat=on|off``
        Enables or disables ACPI Heterogeneous Memory Attribute Table
        (HMAT) support. The default is off.
ERST

HXCOMM Deprecated by -machine
DEF("M", HAS_ARG, QEMU_OPTION_M, "", QEMU_ARCH_ALL)

DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
    "-cpu cpu        select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
STEXI
@item -cpu @var{model}
@findex -cpu
Select CPU model (@code{-cpu help} for list and additional feature selection)
ETEXI
SRST
``-cpu model``
    Select CPU model (``-cpu help`` for list and additional feature
    selection)
ERST

DEF("accel", HAS_ARG, QEMU_OPTION_accel,
    "-accel [accel=]accelerator[,prop[=value][,...]]\n"
    "                select accelerator (kvm, xen, hax, hvf, whpx or tcg; use 'help' for a list)\n"
    "                igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
    "                kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
    "                kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
    "                tb-size=n (TCG translation block cache size)\n"
    "                thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
STEXI
@item -accel @var{name}[,prop=@var{value}[,...]]
@findex -accel
This is used to enable an accelerator. Depending on the target architecture,
kvm, xen, hax, hvf, whpx or tcg can be available. By default, tcg is used. If there is
more than one accelerator specified, the next one is used if the previous one
fails to initialize.
@table @option
@item igd-passthru=on|off
When Xen is in use, this option controls whether Intel integrated graphics
devices can be passed through to the guest (default=off)
@item kernel-irqchip=on|off|split
Controls KVM in-kernel irqchip support.  The default is full acceleration of the
interrupt controllers.  On x86, split irqchip reduces the kernel attack
surface, at a performance cost for non-MSI interrupts.  Disabling the in-kernel
irqchip completely is not recommended except for debugging purposes.
@item kvm-shadow-mem=size
Defines the size of the KVM shadow MMU.
@item tb-size=@var{n}
Controls the size (in MiB) of the TCG translation block cache.
@item thread=single|multi
Controls number of TCG threads. When the TCG is multi-threaded there will be one
thread per vCPU therefor taking advantage of additional host cores. The default
is to enable multi-threading where both the back-end and front-ends support it and
no incompatible TCG features have been enabled (e.g. icount/replay).
@end table
ETEXI
SRST
``-accel name[,prop=value[,...]]``
    This is used to enable an accelerator. Depending on the target
    architecture, kvm, xen, hax, hvf, whpx or tcg can be available. By
    default, tcg is used. If there is more than one accelerator
    specified, the next one is used if the previous one fails to
    initialize.

    ``igd-passthru=on|off``
        When Xen is in use, this option controls whether Intel
        integrated graphics devices can be passed through to the guest
        (default=off)

    ``kernel-irqchip=on|off|split``
        Controls KVM in-kernel irqchip support. The default is full
        acceleration of the interrupt controllers. On x86, split irqchip
        reduces the kernel attack surface, at a performance cost for
        non-MSI interrupts. Disabling the in-kernel irqchip completely
        is not recommended except for debugging purposes.

    ``kvm-shadow-mem=size``
        Defines the size of the KVM shadow MMU.

    ``tb-size=n``
        Controls the size (in MiB) of the TCG translation block cache.

    ``thread=single|multi``
        Controls number of TCG threads. When the TCG is multi-threaded
        there will be one thread per vCPU therefor taking advantage of
        additional host cores. The default is to enable multi-threading
        where both the back-end and front-ends support it and no
        incompatible TCG features have been enabled (e.g.
        icount/replay).
ERST

DEF("smp", HAS_ARG, QEMU_OPTION_smp,
    "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n"
    "                set the number of CPUs to 'n' [default=1]\n"
    "                maxcpus= maximum number of total cpus, including\n"
    "                offline CPUs for hotplug, etc\n"
    "                cores= number of CPU cores on one socket (for PC, it's on one die)\n"
    "                threads= number of threads on one CPU core\n"
    "                dies= number of CPU dies on one socket (for PC only)\n"
    "                sockets= number of discrete sockets in the system\n",
        QEMU_ARCH_ALL)
STEXI
@item -smp [cpus=]@var{n}[,cores=@var{cores}][,threads=@var{threads}][,dies=dies][,sockets=@var{sockets}][,maxcpus=@var{maxcpus}]
@findex -smp
Simulate an SMP system with @var{n} CPUs. On the PC target, up to 255
CPUs are supported. On Sparc32 target, Linux limits the number of usable CPUs
to 4.
For the PC target, the number of @var{cores} per die, the number of @var{threads}
per cores, the number of @var{dies} per packages and the total number of
@var{sockets} can be specified. Missing values will be computed.
If any on the three values is given, the total number of CPUs @var{n} can be omitted.
@var{maxcpus} specifies the maximum number of hotpluggable CPUs.
ETEXI
SRST
``-smp [cpus=]n[,cores=cores][,threads=threads][,dies=dies][,sockets=sockets][,maxcpus=maxcpus]``
    Simulate an SMP system with n CPUs. On the PC target, up to 255 CPUs
    are supported. On Sparc32 target, Linux limits the number of usable
    CPUs to 4. For the PC target, the number of cores per die, the
    number of threads per cores, the number of dies per packages and the
    total number of sockets can be specified. Missing values will be
    computed. If any on the three values is given, the total number of
    CPUs n can be omitted. maxcpus specifies the maximum number of
    hotpluggable CPUs.
ERST

DEF("numa", HAS_ARG, QEMU_OPTION_numa,
    "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
    "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
    "-numa dist,src=source,dst=destination,val=distance\n"
    "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
    "-numa hmat-lb,initiator=node,target=node,hierarchy=memory|first-level|second-level|third-level,data-type=access-latency|read-latency|write-latency[,latency=lat][,bandwidth=bw]\n"
    "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
    QEMU_ARCH_ALL)
STEXI
@item -numa node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
@itemx -numa node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
@itemx -numa dist,src=@var{source},dst=@var{destination},val=@var{distance}
@itemx -numa cpu,node-id=@var{node}[,socket-id=@var{x}][,core-id=@var{y}][,thread-id=@var{z}]
@itemx -numa hmat-lb,initiator=@var{node},target=@var{node},hierarchy=@var{hierarchy},data-type=@var{tpye}[,latency=@var{lat}][,bandwidth=@var{bw}]
@itemx -numa hmat-cache,node-id=@var{node},size=@var{size},level=@var{level}[,associativity=@var{str}][,policy=@var{str}][,line=@var{size}]
@findex -numa
Define a NUMA node and assign RAM and VCPUs to it.
Set the NUMA distance from a source node to a destination node.
Set the ACPI Heterogeneous Memory Attributes for the given nodes.

Legacy VCPU assignment uses @samp{cpus} option where
@var{firstcpu} and @var{lastcpu} are CPU indexes. Each
@samp{cpus} option represent a contiguous range of CPU indexes
(or a single VCPU if @var{lastcpu} is omitted). A non-contiguous
set of VCPUs can be represented by providing multiple @samp{cpus}
options. If @samp{cpus} is omitted on all nodes, VCPUs are automatically
split between them.

For example, the following option assigns VCPUs 0, 1, 2 and 5 to
a NUMA node:
@example
-numa node,cpus=0-2,cpus=5
@end example

@samp{cpu} option is a new alternative to @samp{cpus} option
which uses @samp{socket-id|core-id|thread-id} properties to assign
CPU objects to a @var{node} using topology layout properties of CPU.
The set of properties is machine specific, and depends on used
machine type/@samp{smp} options. It could be queried with
@samp{hotpluggable-cpus} monitor command.
@samp{node-id} property specifies @var{node} to which CPU object
will be assigned, it's required for @var{node} to be declared
with @samp{node} option before it's used with @samp{cpu} option.

For example:
@example
-M pc \
-smp 1,sockets=2,maxcpus=2 \
-numa node,nodeid=0 -numa node,nodeid=1 \
-numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
@end example

@samp{mem} assigns a given RAM amount to a node. @samp{memdev}
assigns RAM from a given memory backend device to a node. If
@samp{mem} and @samp{memdev} are omitted in all nodes, RAM is
split equally between them.

@samp{mem} and @samp{memdev} are mutually exclusive. Furthermore,
if one node uses @samp{memdev}, all of them have to use it.

@samp{initiator} is an additional option that points to an @var{initiator}
NUMA node that has best performance (the lowest latency or largest bandwidth)
to this NUMA @var{node}. Note that this option can be set only when
the machine property 'hmat' is set to 'on'.

Following example creates a machine with 2 NUMA nodes, node 0 has CPU.
node 1 has only memory, and its initiator is node 0. Note that because
node 0 has CPU, by default the initiator of node 0 is itself and must be
itself.
@example
-machine hmat=on \
-m 2G,slots=2,maxmem=4G \
-object memory-backend-ram,size=1G,id=m0 \
-object memory-backend-ram,size=1G,id=m1 \
-numa node,nodeid=0,memdev=m0 \
-numa node,nodeid=1,memdev=m1,initiator=0 \
-smp 2,sockets=2,maxcpus=2  \
-numa cpu,node-id=0,socket-id=0 \
-numa cpu,node-id=0,socket-id=1
@end example

@var{source} and @var{destination} are NUMA node IDs.
@var{distance} is the NUMA distance from @var{source} to @var{destination}.
The distance from a node to itself is always 10. If any pair of nodes is
given a distance, then all pairs must be given distances. Although, when
distances are only given in one direction for each pair of nodes, then
the distances in the opposite directions are assumed to be the same. If,
however, an asymmetrical pair of distances is given for even one node
pair, then all node pairs must be provided distance values for both
directions, even when they are symmetrical. When a node is unreachable
from another node, set the pair's distance to 255.

Note that the -@option{numa} option doesn't allocate any of the
specified resources, it just assigns existing resources to NUMA
nodes. This means that one still has to use the @option{-m},
@option{-smp} options to allocate RAM and VCPUs respectively.

Use @samp{hmat-lb} to set System Locality Latency and Bandwidth Information
between initiator and target NUMA nodes in ACPI Heterogeneous Attribute Memory Table (HMAT).
Initiator NUMA node can create memory requests, usually it has one or more processors.
Target NUMA node contains addressable memory.

In @samp{hmat-lb} option, @var{node} are NUMA node IDs. @var{hierarchy} is the memory
hierarchy of the target NUMA node: if @var{hierarchy} is 'memory', the structure
represents the memory performance; if @var{hierarchy} is 'first-level|second-level|third-level',
this structure represents aggregated performance of memory side caches for each domain.
@var{type} of 'data-type' is type of data represented by this structure instance:
if 'hierarchy' is 'memory', 'data-type' is 'access|read|write' latency or 'access|read|write'
bandwidth of the target memory; if 'hierarchy' is 'first-level|second-level|third-level',
'data-type' is 'access|read|write' hit latency or 'access|read|write' hit bandwidth of the
target memory side cache.

@var{lat} is latency value in nanoseconds. @var{bw} is bandwidth value,
the possible value and units are NUM[M|G|T], mean that the bandwidth value are
NUM byte per second (or MB/s, GB/s or TB/s depending on used suffix).
Note that if latency or bandwidth value is 0, means the corresponding latency or
bandwidth information is not provided.

In @samp{hmat-cache} option, @var{node-id} is the NUMA-id of the memory belongs.
@var{size} is the size of memory side cache in bytes. @var{level} is the cache
level described in this structure, note that the cache level 0 should not be used
with @samp{hmat-cache} option. @var{associativity} is the cache associativity,
the possible value is 'none/direct(direct-mapped)/complex(complex cache indexing)'.
@var{policy} is the write policy. @var{line} is the cache Line size in bytes.

For example, the following options describe 2 NUMA nodes. Node 0 has 2 cpus and
a ram, node 1 has only a ram. The processors in node 0 access memory in node
0 with access-latency 5 nanoseconds, access-bandwidth is 200 MB/s;
The processors in NUMA node 0 access memory in NUMA node 1 with access-latency 10
nanoseconds, access-bandwidth is 100 MB/s.
And for memory side cache information, NUMA node 0 and 1 both have 1 level memory
cache, size is 10KB, policy is write-back, the cache Line size is 8 bytes:
@example
-machine hmat=on \
-m 2G \
-object memory-backend-ram,size=1G,id=m0 \
-object memory-backend-ram,size=1G,id=m1 \
-smp 2 \
-numa node,nodeid=0,memdev=m0 \
-numa node,nodeid=1,memdev=m1,initiator=0 \
-numa cpu,node-id=0,socket-id=0 \
-numa cpu,node-id=0,socket-id=1 \
-numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
-numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
-numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
-numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
-numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
-numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
@end example

ETEXI
SRST
``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``; \ ``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``; \ ``-numa dist,src=source,dst=destination,val=distance``; \ ``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]``; \ ``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]``; \ ``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]``
    Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA
    distance from a source node to a destination node. Set the ACPI
    Heterogeneous Memory Attributes for the given nodes.

    Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and
    lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a
    contiguous range of CPU indexes (or a single VCPU if lastcpu is
    omitted). A non-contiguous set of VCPUs can be represented by
    providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is
    omitted on all nodes, VCPUs are automatically split between them.

    For example, the following option assigns VCPUs 0, 1, 2 and 5 to a
    NUMA node:

    ::

        -numa node,cpus=0-2,cpus=5

    '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option
    which uses '\ ``socket-id|core-id|thread-id``\ ' properties to
    assign CPU objects to a node using topology layout properties of
    CPU. The set of properties is machine specific, and depends on used
    machine type/'\ ``smp``\ ' options. It could be queried with
    '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ '
    property specifies node to which CPU object will be assigned, it's
    required for node to be declared with '\ ``node``\ ' option before
    it's used with '\ ``cpu``\ ' option.

    For example:

    ::

        -M pc \
        -smp 1,sockets=2,maxcpus=2 \
        -numa node,nodeid=0 -numa node,nodeid=1 \
        -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1

    '\ ``mem``\ ' assigns a given RAM amount to a node. '\ ``memdev``\ '
    assigns RAM from a given memory backend device to a node. If
    '\ ``mem``\ ' and '\ ``memdev``\ ' are omitted in all nodes, RAM is
    split equally between them.

    '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive.
    Furthermore, if one node uses '\ ``memdev``\ ', all of them have to
    use it.

    '\ ``initiator``\ ' is an additional option that points to an
    initiator NUMA node that has best performance (the lowest latency or
    largest bandwidth) to this NUMA node. Note that this option can be
    set only when the machine property 'hmat' is set to 'on'.

    Following example creates a machine with 2 NUMA nodes, node 0 has
    CPU. node 1 has only memory, and its initiator is node 0. Note that
    because node 0 has CPU, by default the initiator of node 0 is itself
    and must be itself.

    ::

        -machine hmat=on \
        -m 2G,slots=2,maxmem=4G \
        -object memory-backend-ram,size=1G,id=m0 \
        -object memory-backend-ram,size=1G,id=m1 \
        -numa node,nodeid=0,memdev=m0 \
        -numa node,nodeid=1,memdev=m1,initiator=0 \
        -smp 2,sockets=2,maxcpus=2  \
        -numa cpu,node-id=0,socket-id=0 \
        -numa cpu,node-id=0,socket-id=1

    source and destination are NUMA node IDs. distance is the NUMA
    distance from source to destination. The distance from a node to
    itself is always 10. If any pair of nodes is given a distance, then
    all pairs must be given distances. Although, when distances are only
    given in one direction for each pair of nodes, then the distances in
    the opposite directions are assumed to be the same. If, however, an
    asymmetrical pair of distances is given for even one node pair, then
    all node pairs must be provided distance values for both directions,
    even when they are symmetrical. When a node is unreachable from
    another node, set the pair's distance to 255.

    Note that the -``numa`` option doesn't allocate any of the specified
    resources, it just assigns existing resources to NUMA nodes. This
    means that one still has to use the ``-m``, ``-smp`` options to
    allocate RAM and VCPUs respectively.

    Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
    Information between initiator and target NUMA nodes in ACPI
    Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can
    create memory requests, usually it has one or more processors.
    Target NUMA node contains addressable memory.

    In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is
    the memory hierarchy of the target NUMA node: if hierarchy is
    'memory', the structure represents the memory performance; if
    hierarchy is 'first-level\|second-level\|third-level', this
    structure represents aggregated performance of memory side caches
    for each domain. type of 'data-type' is type of data represented by
    this structure instance: if 'hierarchy' is 'memory', 'data-type' is
    'access\|read\|write' latency or 'access\|read\|write' bandwidth of
    the target memory; if 'hierarchy' is
    'first-level\|second-level\|third-level', 'data-type' is
    'access\|read\|write' hit latency or 'access\|read\|write' hit
    bandwidth of the target memory side cache.

    lat is latency value in nanoseconds. bw is bandwidth value, the
    possible value and units are NUM[M\|G\|T], mean that the bandwidth
    value are NUM byte per second (or MB/s, GB/s or TB/s depending on
    used suffix). Note that if latency or bandwidth value is 0, means
    the corresponding latency or bandwidth information is not provided.

    In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory
    belongs. size is the size of memory side cache in bytes. level is
    the cache level described in this structure, note that the cache
    level 0 should not be used with '\ ``hmat-cache``\ ' option.
    associativity is the cache associativity, the possible value is
    'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
    is the write policy. line is the cache Line size in bytes.

    For example, the following options describe 2 NUMA nodes. Node 0 has
    2 cpus and a ram, node 1 has only a ram. The processors in node 0
    access memory in node 0 with access-latency 5 nanoseconds,
    access-bandwidth is 200 MB/s; The processors in NUMA node 0 access
    memory in NUMA node 1 with access-latency 10 nanoseconds,
    access-bandwidth is 100 MB/s. And for memory side cache information,
    NUMA node 0 and 1 both have 1 level memory cache, size is 10KB,
    policy is write-back, the cache Line size is 8 bytes:

    ::

        -machine hmat=on \
        -m 2G \
        -object memory-backend-ram,size=1G,id=m0 \
        -object memory-backend-ram,size=1G,id=m1 \
        -smp 2 \
        -numa node,nodeid=0,memdev=m0 \
        -numa node,nodeid=1,memdev=m1,initiator=0 \
        -numa cpu,node-id=0,socket-id=0 \
        -numa cpu,node-id=0,socket-id=1 \
        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
        -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
        -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
ERST

DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
    "-add-fd fd=fd,set=set[,opaque=opaque]\n"
    "                Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
STEXI
@item -add-fd fd=@var{fd},set=@var{set}[,opaque=@var{opaque}]
@findex -add-fd

Add a file descriptor to an fd set.  Valid options are:

@table @option
@item fd=@var{fd}
This option defines the file descriptor of which a duplicate is added to fd set.
The file descriptor cannot be stdin, stdout, or stderr.
@item set=@var{set}
This option defines the ID of the fd set to add the file descriptor to.
@item opaque=@var{opaque}
This option defines a free-form string that can be used to describe @var{fd}.
@end table

You can open an image using pre-opened file descriptors from an fd set:
@example
@value{qemu_system} \
 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
 -drive file=/dev/fdset/2,index=0,media=disk
@end example
ETEXI
SRST
``-add-fd fd=fd,set=set[,opaque=opaque]``
    Add a file descriptor to an fd set. Valid options are:

    ``fd=fd``
        This option defines the file descriptor of which a duplicate is
        added to fd set. The file descriptor cannot be stdin, stdout, or
        stderr.

    ``set=set``
        This option defines the ID of the fd set to add the file
        descriptor to.

    ``opaque=opaque``
        This option defines a free-form string that can be used to
        describe fd.

    You can open an image using pre-opened file descriptors from an fd
    set:

    .. parsed-literal::

        |qemu_system| \
         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
         -drive file=/dev/fdset/2,index=0,media=disk
ERST

DEF("set", HAS_ARG, QEMU_OPTION_set,
    "-set group.id.arg=value\n"
    "                set <arg> parameter for item <id> of type <group>\n"
    "                i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
STEXI
@item -set @var{group}.@var{id}.@var{arg}=@var{value}
@findex -set
Set parameter @var{arg} for item @var{id} of type @var{group}
ETEXI
SRST
``-set group.id.arg=value``
    Set parameter arg for item id of type group
ERST

DEF("global", HAS_ARG, QEMU_OPTION_global,
    "-global driver.property=value\n"
    "-global driver=driver,property=property,value=value\n"
    "                set a global default for a driver property\n",
    QEMU_ARCH_ALL)
STEXI
@item -global @var{driver}.@var{prop}=@var{value}
@itemx -global driver=@var{driver},property=@var{property},value=@var{value}
@findex -global
Set default value of @var{driver}'s property @var{prop} to @var{value}, e.g.:

@example
@value{qemu_system_x86} -global ide-hd.physical_block_size=4096 disk-image.img
@end example

In particular, you can use this to set driver properties for devices which are
created automatically by the machine model. To create a device which is not
created automatically and set properties on it, use -@option{device}.

-global @var{driver}.@var{prop}=@var{value} is shorthand for -global
driver=@var{driver},property=@var{prop},value=@var{value}.  The
longhand syntax works even when @var{driver} contains a dot.
ETEXI
SRST
``-global driver.prop=value``; \ ``-global driver=driver,property=property,value=value``
    Set default value of driver's property prop to value, e.g.:

    .. parsed-literal::

        |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img

    In particular, you can use this to set driver properties for devices
    which are created automatically by the machine model. To create a
    device which is not created automatically and set properties on it,
    use -``device``.

    -global driver.prop=value is shorthand for -global
    driver=driver,property=prop,value=value. The longhand syntax works
    even when driver contains a dot.
ERST

DEF("boot", HAS_ARG, QEMU_OPTION_boot,
    "-boot [order=drives][,once=drives][,menu=on|off]\n"
    "      [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
    "                'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
    "                'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
    "                'sp_time': the period that splash picture last if menu=on, unit is ms\n"
    "                'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
    QEMU_ARCH_ALL)
STEXI
@item -boot [order=@var{drives}][,once=@var{drives}][,menu=on|off][,splash=@var{sp_name}][,splash-time=@var{sp_time}][,reboot-timeout=@var{rb_timeout}][,strict=on|off]
@findex -boot
Specify boot order @var{drives} as a string of drive letters. Valid
drive letters depend on the target architecture. The x86 PC uses: a, b
(floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p (Etherboot
from network adapter 1-4), hard disk boot is the default. To apply a
particular boot order only on the first startup, specify it via
@option{once}. Note that the @option{order} or @option{once} parameter
should not be used together with the @option{bootindex} property of
devices, since the firmware implementations normally do not support both
at the same time.

Interactive boot menus/prompts can be enabled via @option{menu=on} as far
as firmware/BIOS supports them. The default is non-interactive boot.

A splash picture could be passed to bios, enabling user to show it as logo,
when option splash=@var{sp_name} is given and menu=on, If firmware/BIOS
supports them. Currently Seabios for X86 system support it.
limitation: The splash file could be a jpeg file or a BMP file in 24 BPP
format(true color). The resolution should be supported by the SVGA mode, so
the recommended is 320x240, 640x480, 800x640.

A timeout could be passed to bios, guest will pause for @var{rb_timeout} ms
when boot failed, then reboot. If @var{rb_timeout} is '-1', guest will not
reboot, qemu passes '-1' to bios by default. Currently Seabios for X86
system support it.

Do strict boot via @option{strict=on} as far as firmware/BIOS
supports it. This only effects when boot priority is changed by
bootindex options. The default is non-strict boot.

@example
# try to boot from network first, then from hard disk
@value{qemu_system_x86} -boot order=nc
# boot from CD-ROM first, switch back to default order after reboot
@value{qemu_system_x86} -boot once=d
# boot with a splash picture for 5 seconds.
@value{qemu_system_x86} -boot menu=on,splash=/root/boot.bmp,splash-time=5000
@end example

Note: The legacy format '-boot @var{drives}' is still supported but its
use is discouraged as it may be removed from future versions.
ETEXI
SRST
``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
    Specify boot order drives as a string of drive letters. Valid drive
    letters depend on the target architecture. The x86 PC uses: a, b
    (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
    (Etherboot from network adapter 1-4), hard disk boot is the default.
    To apply a particular boot order only on the first startup, specify
    it via ``once``. Note that the ``order`` or ``once`` parameter
    should not be used together with the ``bootindex`` property of
    devices, since the firmware implementations normally do not support
    both at the same time.

    Interactive boot menus/prompts can be enabled via ``menu=on`` as far
    as firmware/BIOS supports them. The default is non-interactive boot.

    A splash picture could be passed to bios, enabling user to show it
    as logo, when option splash=sp\_name is given and menu=on, If
    firmware/BIOS supports them. Currently Seabios for X86 system
    support it. limitation: The splash file could be a jpeg file or a
    BMP file in 24 BPP format(true color). The resolution should be
    supported by the SVGA mode, so the recommended is 320x240, 640x480,
    800x640.

    A timeout could be passed to bios, guest will pause for rb\_timeout
    ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
    not reboot, qemu passes '-1' to bios by default. Currently Seabios
    for X86 system support it.

    Do strict boot via ``strict=on`` as far as firmware/BIOS supports
    it. This only effects when boot priority is changed by bootindex
    options. The default is non-strict boot.

    ::

        # try to boot from network first, then from hard disk
        |qemu_system_x86| -boot order=nc
        # boot from CD-ROM first, switch back to default order after reboot
        |qemu_system_x86| -boot once=d
        # boot with a splash picture for 5 seconds.
        |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000

    Note: The legacy format '-boot drives' is still supported but its
    use is discouraged as it may be removed from future versions.
ERST

DEF("m", HAS_ARG, QEMU_OPTION_m,
    "-m [size=]megs[,slots=n,maxmem=size]\n"
    "                configure guest RAM\n"
    "                size: initial amount of guest memory\n"
    "                slots: number of hotplug slots (default: none)\n"
    "                maxmem: maximum amount of guest memory (default: none)\n"
    "NOTE: Some architectures might enforce a specific granularity\n",
    QEMU_ARCH_ALL)
STEXI
@item -m [size=]@var{megs}[,slots=n,maxmem=size]
@findex -m
Sets guest startup RAM size to @var{megs} megabytes. Default is 128 MiB.
Optionally, a suffix of ``M'' or ``G'' can be used to signify a value in
megabytes or gigabytes respectively. Optional pair @var{slots}, @var{maxmem}
could be used to set amount of hotpluggable memory slots and maximum amount of
memory. Note that @var{maxmem} must be aligned to the page size.

For example, the following command-line sets the guest startup RAM size to
1GB, creates 3 slots to hotplug additional memory and sets the maximum
memory the guest can reach to 4GB:

@example
@value{qemu_system} -m 1G,slots=3,maxmem=4G
@end example

If @var{slots} and @var{maxmem} are not specified, memory hotplug won't
be enabled and the guest startup RAM will never increase.
ETEXI
SRST
``-m [size=]megs[,slots=n,maxmem=size]``
    Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
    Optionally, a suffix of "M" or "G" can be used to signify a value in
    megabytes or gigabytes respectively. Optional pair slots, maxmem
    could be used to set amount of hotpluggable memory slots and maximum
    amount of memory. Note that maxmem must be aligned to the page size.

    For example, the following command-line sets the guest startup RAM
    size to 1GB, creates 3 slots to hotplug additional memory and sets
    the maximum memory the guest can reach to 4GB:

    .. parsed-literal::

        |qemu_system| -m 1G,slots=3,maxmem=4G

    If slots and maxmem are not specified, memory hotplug won't be
    enabled and the guest startup RAM will never increase.
ERST

DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
    "-mem-path FILE  provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
STEXI
@item -mem-path @var{path}
@findex -mem-path
Allocate guest RAM from a temporarily created file in @var{path}.
ETEXI
SRST
``-mem-path path``
    Allocate guest RAM from a temporarily created file in path.
ERST

DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
    "-mem-prealloc   preallocate guest memory (use with -mem-path)\n",
    QEMU_ARCH_ALL)
STEXI
@item -mem-prealloc
@findex -mem-prealloc
Preallocate memory when using -mem-path.
ETEXI
SRST
``-mem-prealloc``
    Preallocate memory when using -mem-path.
ERST

DEF("k", HAS_ARG, QEMU_OPTION_k,
    "-k language     use keyboard layout (for example 'fr' for French)\n",
    QEMU_ARCH_ALL)
STEXI
@item -k @var{language}
@findex -k
Use keyboard layout @var{language} (for example @code{fr} for
French). This option is only needed where it is not easy to get raw PC
keycodes (e.g. on Macs, with some X11 servers or with a VNC or curses
display). You don't normally need to use it on PC/Linux or PC/Windows
hosts.

The available layouts are:
@example
ar  de-ch  es  fo     fr-ca  hu  ja  mk     no  pt-br  sv
da  en-gb  et  fr     fr-ch  is  lt  nl     pl  ru     th
de  en-us  fi  fr-be  hr     it  lv  nl-be  pt  sl     tr
@end example

The default is @code{en-us}.
ETEXI
SRST
``-k language``
    Use keyboard layout language (for example ``fr`` for French). This
    option is only needed where it is not easy to get raw PC keycodes
    (e.g. on Macs, with some X11 servers or with a VNC or curses
    display). You don't normally need to use it on PC/Linux or
    PC/Windows hosts.

    The available layouts are:

    ::

        ar  de-ch  es  fo     fr-ca  hu  ja  mk     no  pt-br  sv
        da  en-gb  et  fr     fr-ch  is  lt  nl     pl  ru     th
        de  en-us  fi  fr-be  hr     it  lv  nl-be  pt  sl     tr

    The default is ``en-us``.
ERST


HXCOMM Deprecated by -audiodev
DEF("audio-help", 0, QEMU_OPTION_audio_help,
    "-audio-help     show -audiodev equivalent of the currently specified audio settings\n",
    QEMU_ARCH_ALL)
STEXI
@item -audio-help
@findex -audio-help
Will show the -audiodev equivalent of the currently specified
(deprecated) environment variables.
ETEXI
SRST
``-audio-help``
    Will show the -audiodev equivalent of the currently specified
    (deprecated) environment variables.
ERST

DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
    "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
    "                specifies the audio backend to use\n"
    "                id= identifier of the backend\n"
    "                timer-period= timer period in microseconds\n"
    "                in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
    "                in|out.fixed-settings= use fixed settings for host audio\n"
    "                in|out.frequency= frequency to use with fixed settings\n"
    "                in|out.channels= number of channels to use with fixed settings\n"
    "                in|out.format= sample format to use with fixed settings\n"
    "                valid values: s8, s16, s32, u8, u16, u32\n"
    "                in|out.voices= number of voices to use\n"
    "                in|out.buffer-length= length of buffer in microseconds\n"
    "-audiodev none,id=id,[,prop[=value][,...]]\n"
    "                dummy driver that discards all output\n"
#ifdef CONFIG_AUDIO_ALSA
    "-audiodev alsa,id=id[,prop[=value][,...]]\n"
    "                in|out.dev= name of the audio device to use\n"
    "                in|out.period-length= length of period in microseconds\n"
    "                in|out.try-poll= attempt to use poll mode\n"
    "                threshold= threshold (in microseconds) when playback starts\n"
#endif
#ifdef CONFIG_AUDIO_COREAUDIO
    "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
    "                in|out.buffer-count= number of buffers\n"
#endif
#ifdef CONFIG_AUDIO_DSOUND
    "-audiodev dsound,id=id[,prop[=value][,...]]\n"
    "                latency= add extra latency to playback in microseconds\n"
#endif
#ifdef CONFIG_AUDIO_OSS
    "-audiodev oss,id=id[,prop[=value][,...]]\n"
    "                in|out.dev= path of the audio device to use\n"
    "                in|out.buffer-count= number of buffers\n"
    "                in|out.try-poll= attempt to use poll mode\n"
    "                try-mmap= try using memory mapped access\n"
    "                exclusive= open device in exclusive mode\n"
    "                dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
#endif
#ifdef CONFIG_AUDIO_PA
    "-audiodev pa,id=id[,prop[=value][,...]]\n"
    "                server= PulseAudio server address\n"
    "                in|out.name= source/sink device name\n"
    "                in|out.latency= desired latency in microseconds\n"
#endif
#ifdef CONFIG_AUDIO_SDL
    "-audiodev sdl,id=id[,prop[=value][,...]]\n"
#endif
#ifdef CONFIG_SPICE
    "-audiodev spice,id=id[,prop[=value][,...]]\n"
#endif
    "-audiodev wav,id=id[,prop[=value][,...]]\n"
    "                path= path of wav file to record\n",
    QEMU_ARCH_ALL)
STEXI
@item -audiodev [driver=]@var{driver},id=@var{id}[,@var{prop}[=@var{value}][,...]]
@findex -audiodev
Adds a new audio backend @var{driver} identified by @var{id}.  There are
global and driver specific properties.  Some values can be set
differently for input and output, they're marked with @code{in|out.}.
You can set the input's property with @code{in.@var{prop}} and the
output's property with @code{out.@var{prop}}. For example:
@example
-audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
-audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
@end example

NOTE: parameter validation is known to be incomplete, in many cases
specifying an invalid option causes QEMU to print an error message and
continue emulation without sound.

Valid global options are:

@table @option
@item id=@var{identifier}
Identifies the audio backend.

@item timer-period=@var{period}
Sets the timer @var{period} used by the audio subsystem in microseconds.
Default is 10000 (10 ms).

@item in|out.mixing-engine=on|off
Use QEMU's mixing engine to mix all streams inside QEMU and convert
audio formats when not supported by the backend.  When off,
@var{fixed-settings} must be off too.  Note that disabling this option
means that the selected backend must support multiple streams and the
audio formats used by the virtual cards, otherwise you'll get no sound.
It's not recommended to disable this option unless you want to use 5.1
or 7.1 audio, as mixing engine only supports mono and stereo audio.
Default is on.

@item in|out.fixed-settings=on|off
Use fixed settings for host audio.  When off, it will change based on
how the guest opens the sound card.  In this case you must not specify
@var{frequency}, @var{channels} or @var{format}.  Default is on.

@item in|out.frequency=@var{frequency}
Specify the @var{frequency} to use when using @var{fixed-settings}.
Default is 44100Hz.

@item in|out.channels=@var{channels}
Specify the number of @var{channels} to use when using
@var{fixed-settings}. Default is 2 (stereo).

@item in|out.format=@var{format}
Specify the sample @var{format} to use when using @var{fixed-settings}.
Valid values are: @code{s8}, @code{s16}, @code{s32}, @code{u8},
@code{u16}, @code{u32}. Default is @code{s16}.

@item in|out.voices=@var{voices}
Specify the number of @var{voices} to use.  Default is 1.

@item in|out.buffer-length=@var{usecs}
Sets the size of the buffer in microseconds.

@end table

@item -audiodev none,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a dummy backend that discards all outputs.  This backend has no
backend specific properties.

@item -audiodev alsa,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates backend using the ALSA.  This backend is only available on
Linux.

ALSA specific options are:

@table @option

@item in|out.dev=@var{device}
Specify the ALSA @var{device} to use for input and/or output.  Default
is @code{default}.

@item in|out.period-length=@var{usecs}
Sets the period length in microseconds.

@item in|out.try-poll=on|off
Attempt to use poll mode with the device.  Default is on.

@item threshold=@var{threshold}
Threshold (in microseconds) when playback starts.  Default is 0.

@end table

@item -audiodev coreaudio,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a backend using Apple's Core Audio.  This backend is only
available on Mac OS and only supports playback.

Core Audio specific options are:

@table @option

@item in|out.buffer-count=@var{count}
Sets the @var{count} of the buffers.

@end table

@item -audiodev dsound,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a backend using Microsoft's DirectSound.  This backend is only
available on Windows and only supports playback.

DirectSound specific options are:

@table @option

@item latency=@var{usecs}
Add extra @var{usecs} microseconds latency to playback.  Default is
10000 (10 ms).

@end table

@item -audiodev oss,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a backend using OSS.  This backend is available on most
Unix-like systems.

OSS specific options are:

@table @option

@item in|out.dev=@var{device}
Specify the file name of the OSS @var{device} to use.  Default is
@code{/dev/dsp}.

@item in|out.buffer-count=@var{count}
Sets the @var{count} of the buffers.

@item in|out.try-poll=on|of
Attempt to use poll mode with the device.  Default is on.

@item try-mmap=on|off
Try using memory mapped device access.  Default is off.

@item exclusive=on|off
Open the device in exclusive mode (vmix won't work in this case).
Default is off.

@item dsp-policy=@var{policy}
Sets the timing policy (between 0 and 10, where smaller number means
smaller latency but higher CPU usage).  Use -1 to use buffer sizes
specified by @code{buffer} and @code{buffer-count}.  This option is
ignored if you do not have OSS 4. Default is 5.

@end table

@item -audiodev pa,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a backend using PulseAudio.  This backend is available on most
systems.

PulseAudio specific options are:

@table @option

@item server=@var{server}
Sets the PulseAudio @var{server} to connect to.

@item in|out.name=@var{sink}
Use the specified source/sink for recording/playback.

@item in|out.latency=@var{usecs}
Desired latency in microseconds.  The PulseAudio server will try to honor this
value but actual latencies may be lower or higher.

@end table

@item -audiodev sdl,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a backend using SDL.  This backend is available on most systems,
but you should use your platform's native backend if possible.  This
backend has no backend specific properties.

@item -audiodev spice,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a backend that sends audio through SPICE.  This backend requires
@code{-spice} and automatically selected in that case, so usually you
can ignore this option.  This backend has no backend specific
properties.

@item -audiodev wav,id=@var{id}[,@var{prop}[=@var{value}][,...]]
Creates a backend that writes audio to a WAV file.

Backend specific options are:

@table @option

@item path=@var{path}
Write recorded audio into the specified file.  Default is
@code{qemu.wav}.

@end table
ETEXI
SRST
``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
    Adds a new audio backend driver identified by id. There are global
    and driver specific properties. Some values can be set differently
    for input and output, they're marked with ``in|out.``. You can set
    the input's property with ``in.prop`` and the output's property with
    ``out.prop``. For example:

    ::

        -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
        -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified

    NOTE: parameter validation is known to be incomplete, in many cases
    specifying an invalid option causes QEMU to print an error message
    and continue emulation without sound.

    Valid global options are:

    ``id=identifier``
        Identifies the audio backend.

    ``timer-period=period``
        Sets the timer period used by the audio subsystem in
        microseconds. Default is 10000 (10 ms).

    ``in|out.mixing-engine=on|off``
        Use QEMU's mixing engine to mix all streams inside QEMU and
        convert audio formats when not supported by the backend. When
        off, fixed-settings must be off too. Note that disabling this
        option means that the selected backend must support multiple
        streams and the audio formats used by the virtual cards,
        otherwise you'll get no sound. It's not recommended to disable
        this option unless you want to use 5.1 or 7.1 audio, as mixing
        engine only supports mono and stereo audio. Default is on.

    ``in|out.fixed-settings=on|off``
        Use fixed settings for host audio. When off, it will change
        based on how the guest opens the sound card. In this case you
        must not specify frequency, channels or format. Default is on.

    ``in|out.frequency=frequency``
        Specify the frequency to use when using fixed-settings. Default
        is 44100Hz.

    ``in|out.channels=channels``
        Specify the number of channels to use when using fixed-settings.
        Default is 2 (stereo).

    ``in|out.format=format``
        Specify the sample format to use when using fixed-settings.
        Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
        ``u32``. Default is ``s16``.

    ``in|out.voices=voices``
        Specify the number of voices to use. Default is 1.

    ``in|out.buffer-length=usecs``
        Sets the size of the buffer in microseconds.

``-audiodev none,id=id[,prop[=value][,...]]``
    Creates a dummy backend that discards all outputs. This backend has
    no backend specific properties.

``-audiodev alsa,id=id[,prop[=value][,...]]``
    Creates backend using the ALSA. This backend is only available on
    Linux.

    ALSA specific options are:

    ``in|out.dev=device``
        Specify the ALSA device to use for input and/or output. Default
        is ``default``.

    ``in|out.period-length=usecs``
        Sets the period length in microseconds.

    ``in|out.try-poll=on|off``
        Attempt to use poll mode with the device. Default is on.

    ``threshold=threshold``
        Threshold (in microseconds) when playback starts. Default is 0.

``-audiodev coreaudio,id=id[,prop[=value][,...]]``
    Creates a backend using Apple's Core Audio. This backend is only
    available on Mac OS and only supports playback.

    Core Audio specific options are:

    ``in|out.buffer-count=count``
        Sets the count of the buffers.

``-audiodev dsound,id=id[,prop[=value][,...]]``
    Creates a backend using Microsoft's DirectSound. This backend is
    only available on Windows and only supports playback.

    DirectSound specific options are:

    ``latency=usecs``
        Add extra usecs microseconds latency to playback. Default is
        10000 (10 ms).

``-audiodev oss,id=id[,prop[=value][,...]]``
    Creates a backend using OSS. This backend is available on most
    Unix-like systems.

    OSS specific options are:

    ``in|out.dev=device``
        Specify the file name of the OSS device to use. Default is
        ``/dev/dsp``.

    ``in|out.buffer-count=count``
        Sets the count of the buffers.

    ``in|out.try-poll=on|of``
        Attempt to use poll mode with the device. Default is on.

    ``try-mmap=on|off``
        Try using memory mapped device access. Default is off.

    ``exclusive=on|off``
        Open the device in exclusive mode (vmix won't work in this
        case). Default is off.

    ``dsp-policy=policy``
        Sets the timing policy (between 0 and 10, where smaller number
        means smaller latency but higher CPU usage). Use -1 to use
        buffer sizes specified by ``buffer`` and ``buffer-count``. This
        option is ignored if you do not have OSS 4. Default is 5.

``-audiodev pa,id=id[,prop[=value][,...]]``
    Creates a backend using PulseAudio. This backend is available on
    most systems.

    PulseAudio specific options are:

    ``server=server``
        Sets the PulseAudio server to connect to.

    ``in|out.name=sink``
        Use the specified source/sink for recording/playback.

    ``in|out.latency=usecs``
        Desired latency in microseconds. The PulseAudio server will try
        to honor this value but actual latencies may be lower or higher.

``-audiodev sdl,id=id[,prop[=value][,...]]``
    Creates a backend using SDL. This backend is available on most
    systems, but you should use your platform's native backend if
    possible. This backend has no backend specific properties.

``-audiodev spice,id=id[,prop[=value][,...]]``
    Creates a backend that sends audio through SPICE. This backend
    requires ``-spice`` and automatically selected in that case, so
    usually you can ignore this option. This backend has no backend
    specific properties.

``-audiodev wav,id=id[,prop[=value][,...]]``
    Creates a backend that writes audio to a WAV file.

    Backend specific options are:

    ``path=path``
        Write recorded audio into the specified file. Default is
        ``qemu.wav``.
ERST

DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
    "-soundhw c1,... enable audio support\n"
    "                and only specified sound cards (comma separated list)\n"
    "                use '-soundhw help' to get the list of supported cards\n"
    "                use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
STEXI
@item -soundhw @var{card1}[,@var{card2},...] or -soundhw all
@findex -soundhw
Enable audio and selected sound hardware. Use 'help' to print all
available sound hardware. For example:

@example
@value{qemu_system_x86} -soundhw sb16,adlib disk.img
@value{qemu_system_x86} -soundhw es1370 disk.img
@value{qemu_system_x86} -soundhw ac97 disk.img
@value{qemu_system_x86} -soundhw hda disk.img
@value{qemu_system_x86} -soundhw all disk.img
@value{qemu_system_x86} -soundhw help
@end example

Note that Linux's i810_audio OSS kernel (for AC97) module might
require manually specifying clocking.

@example
modprobe i810_audio clocking=48000
@end example
ETEXI
SRST
``-soundhw card1[,card2,...] or -soundhw all``
    Enable audio and selected sound hardware. Use 'help' to print all
    available sound hardware. For example:

    .. parsed-literal::

        |qemu_system_x86| -soundhw sb16,adlib disk.img
        |qemu_system_x86| -soundhw es1370 disk.img
        |qemu_system_x86| -soundhw ac97 disk.img
        |qemu_system_x86| -soundhw hda disk.img
        |qemu_system_x86| -soundhw all disk.img
        |qemu_system_x86| -soundhw help

    Note that Linux's i810\_audio OSS kernel (for AC97) module might
    require manually specifying clocking.

    ::

        modprobe i810_audio clocking=48000
ERST

DEF("device", HAS_ARG, QEMU_OPTION_device,
    "-device driver[,prop[=value][,...]]\n"
    "                add device (based on driver)\n"
    "                prop=value,... sets driver properties\n"
    "                use '-device help' to print all possible drivers\n"
    "                use '-device driver,help' to print all possible properties\n",
    QEMU_ARCH_ALL)
STEXI
@item -device @var{driver}[,@var{prop}[=@var{value}][,...]]
@findex -device
Add device @var{driver}.  @var{prop}=@var{value} sets driver
properties.  Valid properties depend on the driver.  To get help on
possible drivers and properties, use @code{-device help} and
@code{-device @var{driver},help}.

Some drivers are:
@item -device ipmi-bmc-sim,id=@var{id}[,slave_addr=@var{val}][,sdrfile=@var{file}][,furareasize=@var{val}][,furdatafile=@var{file}][,guid=@var{uuid}]

Add an IPMI BMC.  This is a simulation of a hardware management
interface processor that normally sits on a system.  It provides
a watchdog and the ability to reset and power control the system.
You need to connect this to an IPMI interface to make it useful

The IPMI slave address to use for the BMC.  The default is 0x20.
This address is the BMC's address on the I2C network of management
controllers.  If you don't know what this means, it is safe to ignore
it.

@table @option
@item id=@var{id}
The BMC id for interfaces to use this device.
@item slave_addr=@var{val}
Define slave address to use for the BMC.  The default is 0x20.
@item sdrfile=@var{file}
file containing raw Sensor Data Records (SDR) data. The default is none.
@item fruareasize=@var{val}
size of a Field Replaceable Unit (FRU) area.  The default is 1024.
@item frudatafile=@var{file}
file containing raw Field Replaceable Unit (FRU) inventory data. The default is none.
@item guid=@var{uuid}
value for the GUID for the BMC, in standard UUID format.  If this is set,
get "Get GUID" command to the BMC will return it.  Otherwise "Get GUID"
will return an error.
@end table

@item -device ipmi-bmc-extern,id=@var{id},chardev=@var{id}[,slave_addr=@var{val}]

Add a connection to an external IPMI BMC simulator.  Instead of
locally emulating the BMC like the above item, instead connect
to an external entity that provides the IPMI services.

A connection is made to an external BMC simulator.  If you do this, it
is strongly recommended that you use the "reconnect=" chardev option
to reconnect to the simulator if the connection is lost.  Note that if
this is not used carefully, it can be a security issue, as the
interface has the ability to send resets, NMIs, and power off the VM.
It's best if QEMU makes a connection to an external simulator running
on a secure port on localhost, so neither the simulator nor QEMU is
exposed to any outside network.

See the "lanserv/README.vm" file in the OpenIPMI library for more
details on the external interface.

@item -device isa-ipmi-kcs,bmc=@var{id}[,ioport=@var{val}][,irq=@var{val}]

Add a KCS IPMI interafce on the ISA bus.  This also adds a
corresponding ACPI and SMBIOS entries, if appropriate.

@table @option
@item bmc=@var{id}
The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
@item ioport=@var{val}
Define the I/O address of the interface.  The default is 0xca0 for KCS.
@item irq=@var{val}
Define the interrupt to use.  The default is 5.  To disable interrupts,
set this to 0.
@end table

@item -device isa-ipmi-bt,bmc=@var{id}[,ioport=@var{val}][,irq=@var{val}]

Like the KCS interface, but defines a BT interface.  The default port is
0xe4 and the default interrupt is 5.

ETEXI
SRST
``-device driver[,prop[=value][,...]]``
    Add device driver. prop=value sets driver properties. Valid
    properties depend on the driver. To get help on possible drivers and
    properties, use ``-device help`` and ``-device driver,help``.

    Some drivers are:

``-device ipmi-bmc-sim,id=id[,slave_addr=val][,sdrfile=file][,furareasize=val][,furdatafile=file][,guid=uuid]``
    Add an IPMI BMC. This is a simulation of a hardware management
    interface processor that normally sits on a system. It provides a
    watchdog and the ability to reset and power control the system. You
    need to connect this to an IPMI interface to make it useful

    The IPMI slave address to use for the BMC. The default is 0x20. This
    address is the BMC's address on the I2C network of management
    controllers. If you don't know what this means, it is safe to ignore
    it.

    ``id=id``
        The BMC id for interfaces to use this device.

    ``slave_addr=val``
        Define slave address to use for the BMC. The default is 0x20.

    ``sdrfile=file``
        file containing raw Sensor Data Records (SDR) data. The default
        is none.

    ``fruareasize=val``
        size of a Field Replaceable Unit (FRU) area. The default is
        1024.

    ``frudatafile=file``
        file containing raw Field Replaceable Unit (FRU) inventory data.
        The default is none.

    ``guid=uuid``
        value for the GUID for the BMC, in standard UUID format. If this
        is set, get "Get GUID" command to the BMC will return it.
        Otherwise "Get GUID" will return an error.

``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
    Add a connection to an external IPMI BMC simulator. Instead of
    locally emulating the BMC like the above item, instead connect to an
    external entity that provides the IPMI services.

    A connection is made to an external BMC simulator. If you do this,
    it is strongly recommended that you use the "reconnect=" chardev
    option to reconnect to the simulator if the connection is lost. Note
    that if this is not used carefully, it can be a security issue, as
    the interface has the ability to send resets, NMIs, and power off
    the VM. It's best if QEMU makes a connection to an external
    simulator running on a secure port on localhost, so neither the
    simulator nor QEMU is exposed to any outside network.

    See the "lanserv/README.vm" file in the OpenIPMI library for more
    details on the external interface.

``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
    Add a KCS IPMI interafce on the ISA bus. This also adds a
    corresponding ACPI and SMBIOS entries, if appropriate.

    ``bmc=id``
        The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
        above.

    ``ioport=val``
        Define the I/O address of the interface. The default is 0xca0
        for KCS.

    ``irq=val``
        Define the interrupt to use. The default is 5. To disable
        interrupts, set this to 0.

``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
    Like the KCS interface, but defines a BT interface. The default port
    is 0xe4 and the default interrupt is 5.
ERST

DEF("name", HAS_ARG, QEMU_OPTION_name,
    "-name string1[,process=string2][,debug-threads=on|off]\n"
    "                set the name of the guest\n"
    "                string1 sets the window title and string2 the process name\n"
    "                When debug-threads is enabled, individual threads are given a separate name\n"
    "                NOTE: The thread names are for debugging and not a stable API.\n",
    QEMU_ARCH_ALL)
STEXI
@item -name @var{name}
@findex -name
Sets the @var{name} of the guest.
This name will be displayed in the SDL window caption.
The @var{name} will also be used for the VNC server.
Also optionally set the top visible process name in Linux.
Naming of individual threads can also be enabled on Linux to aid debugging.
ETEXI
SRST
``-name name``
    Sets the name of the guest. This name will be displayed in the SDL
    window caption. The name will also be used for the VNC server. Also
    optionally set the top visible process name in Linux. Naming of
    individual threads can also be enabled on Linux to aid debugging.
ERST

DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
    "-uuid %08x-%04x-%04x-%04x-%012x\n"
    "                specify machine UUID\n", QEMU_ARCH_ALL)
STEXI
@item -uuid @var{uuid}
@findex -uuid
Set system UUID.
ETEXI
SRST
``-uuid uuid``
    Set system UUID.
ERST

STEXI
@end table
ETEXI
DEFHEADING()

DEFHEADING(Block device options:)
STEXI
@table @option
ETEXI

DEF("fda", HAS_ARG, QEMU_OPTION_fda,
    "-fda/-fdb file  use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
STEXI
@item -fda @var{file}
@itemx -fdb @var{file}
@findex -fda
@findex -fdb
Use @var{file} as floppy disk 0/1 image (@pxref{disk_images}).
ETEXI
SRST
``-fda file``; \ ``-fdb file``
    Use file as floppy disk 0/1 image (see
    :ref:`disk_005fimages`).
ERST

DEF("hda", HAS_ARG, QEMU_OPTION_hda,
    "-hda/-hdb file  use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL)
DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
    "-hdc/-hdd file  use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL)
DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
STEXI
@item -hda @var{file}
@itemx -hdb @var{file}
@itemx -hdc @var{file}
@itemx -hdd @var{file}
@findex -hda
@findex -hdb
@findex -hdc
@findex -hdd
Use @var{file} as hard disk 0, 1, 2 or 3 image (@pxref{disk_images}).
ETEXI
SRST
``-hda file``; \ ``-hdb file``; \ ``-hdc file``; \ ``-hdd file``
    Use file as hard disk 0, 1, 2 or 3 image (see
    :ref:`disk_005fimages`).
ERST

DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
    "-cdrom file     use 'file' as IDE cdrom image (cdrom is ide1 master)\n",
    QEMU_ARCH_ALL)
STEXI
@item -cdrom @var{file}
@findex -cdrom
Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
@option{-cdrom} at the same time). You can use the host CD-ROM by
using @file{/dev/cdrom} as filename.
ETEXI
SRST
``-cdrom file``
    Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at
    the same time). You can use the host CD-ROM by using ``/dev/cdrom``
    as filename.
ERST

DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
    "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
    "          [,read-only=on|off][,auto-read-only=on|off]\n"
    "          [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
    "          [,driver specific parameters...]\n"
    "                configure a block backend\n", QEMU_ARCH_ALL)
STEXI
@item -blockdev @var{option}[,@var{option}[,@var{option}[,...]]]
@findex -blockdev

Define a new block driver node. Some of the options apply to all block drivers,
other options are only accepted for a specific block driver. See below for a
list of generic options and options for the most common block drivers.

Options that expect a reference to another node (e.g. @code{file}) can be
given in two ways. Either you specify the node name of an already existing node
(file=@var{node-name}), or you define a new node inline, adding options
for the referenced node after a dot (file.filename=@var{path},file.aio=native).

A block driver node created with @option{-blockdev} can be used for a guest
device by specifying its node name for the @code{drive} property in a
@option{-device} argument that defines a block device.

@table @option
@item Valid options for any block driver node:

@table @code
@item driver
Specifies the block driver to use for the given node.
@item node-name
This defines the name of the block driver node by which it will be referenced
later. The name must be unique, i.e. it must not match the name of a different
block driver node, or (if you use @option{-drive} as well) the ID of a drive.

If no node name is specified, it is automatically generated. The generated node
name is not intended to be predictable and changes between QEMU invocations.
For the top level, an explicit node name must be specified.
@item read-only
Open the node read-only. Guest write attempts will fail.

Note that some block drivers support only read-only access, either generally or
in certain configurations. In this case, the default value
@option{read-only=off} does not work and the option must be specified
explicitly.
@item auto-read-only
If @option{auto-read-only=on} is set, QEMU may fall back to read-only usage
even when @option{read-only=off} is requested, or even switch between modes as
needed, e.g. depending on whether the image file is writable or whether a
writing user is attached to the node.
@item force-share
Override the image locking system of QEMU by forcing the node to utilize
weaker shared access for permissions where it would normally request exclusive
access.  When there is the potential for multiple instances to have the same
file open (whether this invocation of QEMU is the first or the second
instance), both instances must permit shared access for the second instance to
succeed at opening the file.

Enabling @option{force-share=on} requires @option{read-only=on}.
@item cache.direct
The host page cache can be avoided with @option{cache.direct=on}. This will
attempt to do disk IO directly to the guest's memory. QEMU may still perform an
internal copy of the data.
@item cache.no-flush
In case you don't care about data integrity over host failures, you can use
@option{cache.no-flush=on}. This option tells QEMU that it never needs to write
any data to the disk but can instead keep things in cache. If anything goes
wrong, like your host losing power, the disk storage getting disconnected
accidentally, etc. your image will most probably be rendered unusable.
@item discard=@var{discard}
@var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and controls
whether @code{discard} (also known as @code{trim} or @code{unmap}) requests are
ignored or passed to the filesystem. Some machine types may not support
discard requests.
@item detect-zeroes=@var{detect-zeroes}
@var{detect-zeroes} is "off", "on" or "unmap" and enables the automatic
conversion of plain zero writes by the OS to driver specific optimized
zero write commands. You may even choose "unmap" if @var{discard} is set
to "unmap" to allow a zero write to be converted to an @code{unmap} operation.
@end table

@item Driver-specific options for @code{file}

This is the protocol-level block driver for accessing regular files.

@table @code
@item filename
The path to the image file in the local filesystem
@item aio
Specifies the AIO backend (threads/native, default: threads)
@item locking
Specifies whether the image file is protected with Linux OFD / POSIX locks. The
default is to use the Linux Open File Descriptor API if available, otherwise no
lock is applied.  (auto/on/off, default: auto)
@end table
Example:
@example
-blockdev driver=file,node-name=disk,filename=disk.img
@end example

@item Driver-specific options for @code{raw}

This is the image format block driver for raw images. It is usually
stacked on top of a protocol level block driver such as @code{file}.

@table @code
@item file
Reference to or definition of the data source block driver node
(e.g. a @code{file} driver node)
@end table
Example 1:
@example
-blockdev driver=file,node-name=disk_file,filename=disk.img
-blockdev driver=raw,node-name=disk,file=disk_file
@end example
Example 2:
@example
-blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
@end example

@item Driver-specific options for @code{qcow2}

This is the image format block driver for qcow2 images. It is usually
stacked on top of a protocol level block driver such as @code{file}.

@table @code
@item file
Reference to or definition of the data source block driver node
(e.g. a @code{file} driver node)

@item backing
Reference to or definition of the backing file block device (default is taken
from the image file). It is allowed to pass @code{null} here in order to disable
the default backing file.

@item lazy-refcounts
Whether to enable the lazy refcounts feature (on/off; default is taken from the
image file)

@item cache-size
The maximum total size of the L2 table and refcount block caches in bytes
(default: the sum of l2-cache-size and refcount-cache-size)

@item l2-cache-size
The maximum size of the L2 table cache in bytes
(default: if cache-size is not specified - 32M on Linux platforms, and 8M on
non-Linux platforms; otherwise, as large as possible within the cache-size,
while permitting the requested or the minimal refcount cache size)

@item refcount-cache-size
The maximum size of the refcount block cache in bytes
(default: 4 times the cluster size; or if cache-size is specified, the part of
it which is not used for the L2 cache)

@item cache-clean-interval
Clean unused entries in the L2 and refcount caches. The interval is in seconds.
The default value is 600 on supporting platforms, and 0 on other platforms.
Setting it to 0 disables this feature.

@item pass-discard-request
Whether discard requests to the qcow2 device should be forwarded to the data
source (on/off; default: on if discard=unmap is specified, off otherwise)

@item pass-discard-snapshot
Whether discard requests for the data source should be issued when a snapshot
operation (e.g. deleting a snapshot) frees clusters in the qcow2 file (on/off;
default: on)

@item pass-discard-other
Whether discard requests for the data source should be issued on other
occasions where a cluster gets freed (on/off; default: off)

@item overlap-check
Which overlap checks to perform for writes to the image
(none/constant/cached/all; default: cached). For details or finer
granularity control refer to the QAPI documentation of @code{blockdev-add}.
@end table

Example 1:
@example
-blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
-blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
@end example
Example 2:
@example
-blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
@end example

@item Driver-specific options for other drivers
Please refer to the QAPI documentation of the @code{blockdev-add} QMP command.

@end table

ETEXI
SRST
``-blockdev option[,option[,option[,...]]]``
    Define a new block driver node. Some of the options apply to all
    block drivers, other options are only accepted for a specific block
    driver. See below for a list of generic options and options for the
    most common block drivers.

    Options that expect a reference to another node (e.g. ``file``) can
    be given in two ways. Either you specify the node name of an already
    existing node (file=node-name), or you define a new node inline,
    adding options for the referenced node after a dot
    (file.filename=path,file.aio=native).

    A block driver node created with ``-blockdev`` can be used for a
    guest device by specifying its node name for the ``drive`` property
    in a ``-device`` argument that defines a block device.

    ``Valid options for any block driver node:``
        ``driver``
            Specifies the block driver to use for the given node.

        ``node-name``
            This defines the name of the block driver node by which it
            will be referenced later. The name must be unique, i.e. it
            must not match the name of a different block driver node, or
            (if you use ``-drive`` as well) the ID of a drive.

            If no node name is specified, it is automatically generated.
            The generated node name is not intended to be predictable
            and changes between QEMU invocations. For the top level, an
            explicit node name must be specified.

        ``read-only``
            Open the node read-only. Guest write attempts will fail.

            Note that some block drivers support only read-only access,
            either generally or in certain configurations. In this case,
            the default value ``read-only=off`` does not work and the
            option must be specified explicitly.

        ``auto-read-only``
            If ``auto-read-only=on`` is set, QEMU may fall back to
            read-only usage even when ``read-only=off`` is requested, or
            even switch between modes as needed, e.g. depending on
            whether the image file is writable or whether a writing user
            is attached to the node.

        ``force-share``
            Override the image locking system of QEMU by forcing the
            node to utilize weaker shared access for permissions where
            it would normally request exclusive access. When there is
            the potential for multiple instances to have the same file
            open (whether this invocation of QEMU is the first or the
            second instance), both instances must permit shared access
            for the second instance to succeed at opening the file.

            Enabling ``force-share=on`` requires ``read-only=on``.

        ``cache.direct``
            The host page cache can be avoided with ``cache.direct=on``.
            This will attempt to do disk IO directly to the guest's
            memory. QEMU may still perform an internal copy of the data.

        ``cache.no-flush``
            In case you don't care about data integrity over host
            failures, you can use ``cache.no-flush=on``. This option
            tells QEMU that it never needs to write any data to the disk
            but can instead keep things in cache. If anything goes
            wrong, like your host losing power, the disk storage getting
            disconnected accidentally, etc. your image will most
            probably be rendered unusable.

        ``discard=discard``
            discard is one of "ignore" (or "off") or "unmap" (or "on")
            and controls whether ``discard`` (also known as ``trim`` or
            ``unmap``) requests are ignored or passed to the filesystem.
            Some machine types may not support discard requests.

        ``detect-zeroes=detect-zeroes``
            detect-zeroes is "off", "on" or "unmap" and enables the
            automatic conversion of plain zero writes by the OS to
            driver specific optimized zero write commands. You may even
            choose "unmap" if discard is set to "unmap" to allow a zero
            write to be converted to an ``unmap`` operation.

    ``Driver-specific options for file``
        This is the protocol-level block driver for accessing regular
        files.

        ``filename``
            The path to the image file in the local filesystem

        ``aio``
            Specifies the AIO backend (threads/native, default: threads)

        ``locking``
            Specifies whether the image file is protected with Linux OFD
            / POSIX locks. The default is to use the Linux Open File
            Descriptor API if available, otherwise no lock is applied.
            (auto/on/off, default: auto)

        Example:

        ::

            -blockdev driver=file,node-name=disk,filename=disk.img

    ``Driver-specific options for raw``
        This is the image format block driver for raw images. It is
        usually stacked on top of a protocol level block driver such as
        ``file``.

        ``file``
            Reference to or definition of the data source block driver
            node (e.g. a ``file`` driver node)

        Example 1:

        ::

            -blockdev driver=file,node-name=disk_file,filename=disk.img
            -blockdev driver=raw,node-name=disk,file=disk_file

        Example 2:

        ::

            -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img

    ``Driver-specific options for qcow2``
        This is the image format block driver for qcow2 images. It is
        usually stacked on top of a protocol level block driver such as
        ``file``.

        ``file``
            Reference to or definition of the data source block driver
            node (e.g. a ``file`` driver node)

        ``backing``
            Reference to or definition of the backing file block device
            (default is taken from the image file). It is allowed to
            pass ``null`` here in order to disable the default backing
            file.

        ``lazy-refcounts``
            Whether to enable the lazy refcounts feature (on/off;
            default is taken from the image file)

        ``cache-size``
            The maximum total size of the L2 table and refcount block
            caches in bytes (default: the sum of l2-cache-size and
            refcount-cache-size)

        ``l2-cache-size``
            The maximum size of the L2 table cache in bytes (default: if
            cache-size is not specified - 32M on Linux platforms, and 8M
            on non-Linux platforms; otherwise, as large as possible
            within the cache-size, while permitting the requested or the
            minimal refcount cache size)

        ``refcount-cache-size``
            The maximum size of the refcount block cache in bytes
            (default: 4 times the cluster size; or if cache-size is
            specified, the part of it which is not used for the L2
            cache)

        ``cache-clean-interval``
            Clean unused entries in the L2 and refcount caches. The
            interval is in seconds. The default value is 600 on
            supporting platforms, and 0 on other platforms. Setting it
            to 0 disables this feature.

        ``pass-discard-request``
            Whether discard requests to the qcow2 device should be
            forwarded to the data source (on/off; default: on if
            discard=unmap is specified, off otherwise)

        ``pass-discard-snapshot``
            Whether discard requests for the data source should be
            issued when a snapshot operation (e.g. deleting a snapshot)
            frees clusters in the qcow2 file (on/off; default: on)

        ``pass-discard-other``
            Whether discard requests for the data source should be
            issued on other occasions where a cluster gets freed
            (on/off; default: off)

        ``overlap-check``
            Which overlap checks to perform for writes to the image
            (none/constant/cached/all; default: cached). For details or
            finer granularity control refer to the QAPI documentation of
            ``blockdev-add``.

        Example 1:

        ::

            -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
            -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216

        Example 2:

        ::

            -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2

    ``Driver-specific options for other drivers``
        Please refer to the QAPI documentation of the ``blockdev-add``
        QMP command.
ERST

DEF("drive", HAS_ARG, QEMU_OPTION_drive,
    "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
    "       [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
    "       [,snapshot=on|off][,rerror=ignore|stop|report]\n"
    "       [,werror=ignore|stop|report|enospc][,id=name][,aio=threads|native]\n"
    "       [,readonly=on|off][,copy-on-read=on|off]\n"
    "       [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
    "       [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
    "       [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
    "       [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
    "       [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
    "       [[,iops_size=is]]\n"
    "       [[,group=g]]\n"
    "                use 'file' as a drive image\n", QEMU_ARCH_ALL)
STEXI
@item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
@findex -drive

Define a new drive. This includes creating a block driver node (the backend) as
well as a guest device, and is mostly a shortcut for defining the corresponding
@option{-blockdev} and @option{-device} options.

@option{-drive} accepts all options that are accepted by @option{-blockdev}. In
addition, it knows the following options:

@table @option
@item file=@var{file}
This option defines which disk image (@pxref{disk_images}) to use with
this drive. If the filename contains comma, you must double it
(for instance, "file=my,,file" to use file "my,file").

Special files such as iSCSI devices can be specified using protocol
specific URLs. See the section for "Device URL Syntax" for more information.
@item if=@var{interface}
This option defines on which type on interface the drive is connected.
Available types are: ide, scsi, sd, mtd, floppy, pflash, virtio, none.
@item bus=@var{bus},unit=@var{unit}
These options define where is connected the drive by defining the bus number and
the unit id.
@item index=@var{index}
This option defines where is connected the drive by using an index in the list
of available connectors of a given interface type.
@item media=@var{media}
This option defines the type of the media: disk or cdrom.
@item snapshot=@var{snapshot}
@var{snapshot} is "on" or "off" and controls snapshot mode for the given drive
(see @option{-snapshot}).
@item cache=@var{cache}
@var{cache} is "none", "writeback", "unsafe", "directsync" or "writethrough"
and controls how the host cache is used to access block data. This is a
shortcut that sets the @option{cache.direct} and @option{cache.no-flush}
options (as in @option{-blockdev}), and additionally @option{cache.writeback},
which provides a default for the @option{write-cache} option of block guest
devices (as in @option{-device}). The modes correspond to the following
settings:

@c Our texi2pod.pl script doesn't support @multitable, so fall back to using
@c plain ASCII art (well, UTF-8 art really). This looks okay both in the manpage
@c and the HTML output.
@example
@             │ cache.writeback   cache.direct   cache.no-flush
─────────────┼─────────────────────────────────────────────────
writeback    │ on                off            off
none         │ on                on             off
writethrough │ off               off            off
directsync   │ off               on             off
unsafe       │ on                off            on
@end example

The default mode is @option{cache=writeback}.

@item aio=@var{aio}
@var{aio} is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO.
@item format=@var{format}
Specify which disk @var{format} will be used rather than detecting
the format.  Can be used to specify format=raw to avoid interpreting
an untrusted format header.
@item werror=@var{action},rerror=@var{action}
Specify which @var{action} to take on write and read errors. Valid actions are:
"ignore" (ignore the error and try to continue), "stop" (pause QEMU),
"report" (report the error to the guest), "enospc" (pause QEMU only if the
host disk is full; report the error to the guest otherwise).
The default setting is @option{werror=enospc} and @option{rerror=report}.
@item copy-on-read=@var{copy-on-read}
@var{copy-on-read} is "on" or "off" and enables whether to copy read backing
file sectors into the image file.
@item bps=@var{b},bps_rd=@var{r},bps_wr=@var{w}
Specify bandwidth throttling limits in bytes per second, either for all request
types or for reads or writes only.  Small values can lead to timeouts or hangs
inside the guest.  A safe minimum for disks is 2 MB/s.
@item bps_max=@var{bm},bps_rd_max=@var{rm},bps_wr_max=@var{wm}
Specify bursts in bytes per second, either for all request types or for reads
or writes only.  Bursts allow the guest I/O to spike above the limit
temporarily.
@item iops=@var{i},iops_rd=@var{r},iops_wr=@var{w}
Specify request rate limits in requests per second, either for all request
types or for reads or writes only.
@item iops_max=@var{bm},iops_rd_max=@var{rm},iops_wr_max=@var{wm}
Specify bursts in requests per second, either for all request types or for reads
or writes only.  Bursts allow the guest I/O to spike above the limit
temporarily.
@item iops_size=@var{is}
Let every @var{is} bytes of a request count as a new request for iops
throttling purposes.  Use this option to prevent guests from circumventing iops
limits by sending fewer but larger requests.
@item group=@var{g}
Join a throttling quota group with given name @var{g}.  All drives that are
members of the same group are accounted for together.  Use this option to
prevent guests from circumventing throttling limits by using many small disks
instead of a single larger disk.
@end table

By default, the @option{cache.writeback=on} mode is used. It will report data
writes as completed as soon as the data is present in the host page cache.
This is safe as long as your guest OS makes sure to correctly flush disk caches
where needed. If your guest OS does not handle volatile disk write caches
correctly and your host crashes or loses power, then the guest may experience
data corruption.

For such guests, you should consider using @option{cache.writeback=off}. This
means that the host page cache will be used to read and write data, but write
notification will be sent to the guest only after QEMU has made sure to flush
each write to the disk. Be aware that this has a major impact on performance.

When using the @option{-snapshot} option, unsafe caching is always used.

Copy-on-read avoids accessing the same backing file sectors repeatedly and is
useful when the backing file is over a slow network.  By default copy-on-read
is off.

Instead of @option{-cdrom} you can use:
@example
@value{qemu_system} -drive file=file,index=2,media=cdrom
@end example

Instead of @option{-hda}, @option{-hdb}, @option{-hdc}, @option{-hdd}, you can
use:
@example
@value{qemu_system} -drive file=file,index=0,media=disk
@value{qemu_system} -drive file=file,index=1,media=disk
@value{qemu_system} -drive file=file,index=2,media=disk
@value{qemu_system} -drive file=file,index=3,media=disk
@end example

You can open an image using pre-opened file descriptors from an fd set:
@example
@value{qemu_system} \
 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
 -drive file=/dev/fdset/2,index=0,media=disk
@end example

You can connect a CDROM to the slave of ide0:
@example
@value{qemu_system_x86} -drive file=file,if=ide,index=1,media=cdrom
@end example

If you don't specify the "file=" argument, you define an empty drive:
@example
@value{qemu_system_x86} -drive if=ide,index=1,media=cdrom
@end example

Instead of @option{-fda}, @option{-fdb}, you can use:
@example
@value{qemu_system_x86} -drive file=file,index=0,if=floppy
@value{qemu_system_x86} -drive file=file,index=1,if=floppy
@end example

By default, @var{interface} is "ide" and @var{index} is automatically
incremented:
@example
@value{qemu_system_x86} -drive file=a -drive file=b"
@end example
is interpreted like:
@example
@value{qemu_system_x86} -hda a -hdb b
@end example
ETEXI
SRST
``-drive option[,option[,option[,...]]]``
    Define a new drive. This includes creating a block driver node (the
    backend) as well as a guest device, and is mostly a shortcut for
    defining the corresponding ``-blockdev`` and ``-device`` options.

    ``-drive`` accepts all options that are accepted by ``-blockdev``.
    In addition, it knows the following options:

    ``file=file``
        This option defines which disk image (see
        :ref:`disk_005fimages`) to use with this drive. If
        the filename contains comma, you must double it (for instance,
        "file=my,,file" to use file "my,file").

        Special files such as iSCSI devices can be specified using
        protocol specific URLs. See the section for "Device URL Syntax"
        for more information.

    ``if=interface``
        This option defines on which type on interface the drive is
        connected. Available types are: ide, scsi, sd, mtd, floppy,
        pflash, virtio, none.

    ``bus=bus,unit=unit``
        These options define where is connected the drive by defining
        the bus number and the unit id.

    ``index=index``
        This option defines where is connected the drive by using an
        index in the list of available connectors of a given interface
        type.

    ``media=media``
        This option defines the type of the media: disk or cdrom.

    ``snapshot=snapshot``
        snapshot is "on" or "off" and controls snapshot mode for the
        given drive (see ``-snapshot``).

    ``cache=cache``
        cache is "none", "writeback", "unsafe", "directsync" or
        "writethrough" and controls how the host cache is used to access
        block data. This is a shortcut that sets the ``cache.direct``
        and ``cache.no-flush`` options (as in ``-blockdev``), and
        additionally ``cache.writeback``, which provides a default for
        the ``write-cache`` option of block guest devices (as in
        ``-device``). The modes correspond to the following settings:

        ::

                         │ cache.writeback   cache.direct   cache.no-flush
            ─────────────┼─────────────────────────────────────────────────
            writeback    │ on                off            off
            none         │ on                on             off
            writethrough │ off               off            off
            directsync   │ off               on             off
            unsafe       │ on                off            on

        The default mode is ``cache=writeback``.

    ``aio=aio``
        aio is "threads", or "native" and selects between pthread based
        disk I/O and native Linux AIO.

    ``format=format``
        Specify which disk format will be used rather than detecting the
        format. Can be used to specify format=raw to avoid interpreting
        an untrusted format header.

    ``werror=action,rerror=action``
        Specify which action to take on write and read errors. Valid
        actions are: "ignore" (ignore the error and try to continue),
        "stop" (pause QEMU), "report" (report the error to the guest),
        "enospc" (pause QEMU only if the host disk is full; report the
        error to the guest otherwise). The default setting is
        ``werror=enospc`` and ``rerror=report``.

    ``copy-on-read=copy-on-read``
        copy-on-read is "on" or "off" and enables whether to copy read
        backing file sectors into the image file.

    ``bps=b,bps_rd=r,bps_wr=w``
        Specify bandwidth throttling limits in bytes per second, either
        for all request types or for reads or writes only. Small values
        can lead to timeouts or hangs inside the guest. A safe minimum
        for disks is 2 MB/s.

    ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
        Specify bursts in bytes per second, either for all request types
        or for reads or writes only. Bursts allow the guest I/O to spike
        above the limit temporarily.

    ``iops=i,iops_rd=r,iops_wr=w``
        Specify request rate limits in requests per second, either for
        all request types or for reads or writes only.

    ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
        Specify bursts in requests per second, either for all request
        types or for reads or writes only. Bursts allow the guest I/O to
        spike above the limit temporarily.

    ``iops_size=is``
        Let every is bytes of a request count as a new request for iops
        throttling purposes. Use this option to prevent guests from
        circumventing iops limits by sending fewer but larger requests.

    ``group=g``
        Join a throttling quota group with given name g. All drives that
        are members of the same group are accounted for together. Use
        this option to prevent guests from circumventing throttling
        limits by using many small disks instead of a single larger
        disk.

    By default, the ``cache.writeback=on`` mode is used. It will report
    data writes as completed as soon as the data is present in the host
    page cache. This is safe as long as your guest OS makes sure to
    correctly flush disk caches where needed. If your guest OS does not
    handle volatile disk write caches correctly and your host crashes or
    loses power, then the guest may experience data corruption.

    For such guests, you should consider using ``cache.writeback=off``.
    This means that the host page cache will be used to read and write
    data, but write notification will be sent to the guest only after
    QEMU has made sure to flush each write to the disk. Be aware that
    this has a major impact on performance.

    When using the ``-snapshot`` option, unsafe caching is always used.

    Copy-on-read avoids accessing the same backing file sectors
    repeatedly and is useful when the backing file is over a slow
    network. By default copy-on-read is off.

    Instead of ``-cdrom`` you can use:

    .. parsed-literal::

        |qemu_system| -drive file=file,index=2,media=cdrom

    Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:

    .. parsed-literal::

        |qemu_system| -drive file=file,index=0,media=disk
        |qemu_system| -drive file=file,index=1,media=disk
        |qemu_system| -drive file=file,index=2,media=disk
        |qemu_system| -drive file=file,index=3,media=disk

    You can open an image using pre-opened file descriptors from an fd
    set:

    .. parsed-literal::

        |qemu_system| \
         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
         -drive file=/dev/fdset/2,index=0,media=disk

    You can connect a CDROM to the slave of ide0:

    .. parsed-literal::

        |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom

    If you don't specify the "file=" argument, you define an empty
    drive:

    .. parsed-literal::

        |qemu_system_x86| -drive if=ide,index=1,media=cdrom

    Instead of ``-fda``, ``-fdb``, you can use:

    .. parsed-literal::

        |qemu_system_x86| -drive file=file,index=0,if=floppy
        |qemu_system_x86| -drive file=file,index=1,if=floppy

    By default, interface is "ide" and index is automatically
    incremented:

    .. parsed-literal::

        |qemu_system_x86| -drive file=a -drive file=b"

    is interpreted like:

    .. parsed-literal::

        |qemu_system_x86| -hda a -hdb b
ERST

DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
    "-mtdblock file  use 'file' as on-board Flash memory image\n",
    QEMU_ARCH_ALL)
STEXI
@item -mtdblock @var{file}
@findex -mtdblock
Use @var{file} as on-board Flash memory image.
ETEXI
SRST
``-mtdblock file``
    Use file as on-board Flash memory image.
ERST

DEF("sd", HAS_ARG, QEMU_OPTION_sd,
    "-sd file        use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
STEXI
@item -sd @var{file}
@findex -sd
Use @var{file} as SecureDigital card image.
ETEXI
SRST
``-sd file``
    Use file as SecureDigital card image.
ERST

DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
    "-pflash file    use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
STEXI
@item -pflash @var{file}
@findex -pflash
Use @var{file} as a parallel flash image.
ETEXI
SRST
``-pflash file``
    Use file as a parallel flash image.
ERST

DEF("snapshot", 0, QEMU_OPTION_snapshot,
    "-snapshot       write to temporary files instead of disk image files\n",
    QEMU_ARCH_ALL)
STEXI
@item -snapshot
@findex -snapshot
Write to temporary files instead of disk image files. In this case,
the raw disk image you use is not written back. You can however force
the write back by pressing @key{C-a s} (@pxref{disk_images}).
ETEXI
SRST
``-snapshot``
    Write to temporary files instead of disk image files. In this case,
    the raw disk image you use is not written back. You can however
    force the write back by pressing C-a s (see
    :ref:`disk_005fimages`).
ERST

DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
    "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
    " [,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode]\n"
    " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
    " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
    " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
    " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
    " [[,throttling.iops-size=is]]\n"
    "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly]\n"
    "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly]\n"
    "-fsdev synth,id=id\n",
    QEMU_ARCH_ALL)

STEXI

@item -fsdev local,id=@var{id},path=@var{path},security_model=@var{security_model} [,writeout=@var{writeout}][,readonly][,fmode=@var{fmode}][,dmode=@var{dmode}] [,throttling.@var{option}=@var{value}[,throttling.@var{option}=@var{value}[,...]]]
@itemx -fsdev proxy,id=@var{id},socket=@var{socket}[,writeout=@var{writeout}][,readonly]
@itemx -fsdev proxy,id=@var{id},sock_fd=@var{sock_fd}[,writeout=@var{writeout}][,readonly]
@itemx -fsdev synth,id=@var{id}[,readonly]
@findex -fsdev
Define a new file system device. Valid options are:
@table @option
@item local
Accesses to the filesystem are done by QEMU.
@item proxy
Accesses to the filesystem are done by virtfs-proxy-helper(1).
@item synth
Synthetic filesystem, only used by QTests.
@item id=@var{id}
Specifies identifier for this device.
@item path=@var{path}
Specifies the export path for the file system device. Files under
this path will be available to the 9p client on the guest.
@item security_model=@var{security_model}
Specifies the security model to be used for this export path.
Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none".
In "passthrough" security model, files are stored using the same
credentials as they are created on the guest. This requires QEMU
to run as root. In "mapped-xattr" security model, some of the file
attributes like uid, gid, mode bits and link target are stored as
file attributes. For "mapped-file" these attributes are stored in the
hidden .virtfs_metadata directory. Directories exported by this security model cannot
interact with other unix tools. "none" security model is same as
passthrough except the sever won't report failures if it fails to
set file attributes like ownership. Security model is mandatory
only for local fsdriver. Other fsdrivers (like proxy) don't take
security model as a parameter.
@item writeout=@var{writeout}
This is an optional argument. The only supported value is "immediate".
This means that host page cache will be used to read and write data but
write notification will be sent to the guest only when the data has been
reported as written by the storage subsystem.
@item readonly
Enables exporting 9p share as a readonly mount for guests. By default
read-write access is given.
@item socket=@var{socket}
Enables proxy filesystem driver to use passed socket file for communicating
with virtfs-proxy-helper(1).
@item sock_fd=@var{sock_fd}
Enables proxy filesystem driver to use passed socket descriptor for
communicating with virtfs-proxy-helper(1). Usually a helper like libvirt
will create socketpair and pass one of the fds as sock_fd.
@item fmode=@var{fmode}
Specifies the default mode for newly created files on the host. Works only
with security models "mapped-xattr" and "mapped-file".
@item dmode=@var{dmode}
Specifies the default mode for newly created directories on the host. Works
only with security models "mapped-xattr" and "mapped-file".
@item throttling.bps-total=@var{b},throttling.bps-read=@var{r},throttling.bps-write=@var{w}
Specify bandwidth throttling limits in bytes per second, either for all request
types or for reads or writes only.
@item throttling.bps-total-max=@var{bm},bps-read-max=@var{rm},bps-write-max=@var{wm}
Specify bursts in bytes per second, either for all request types or for reads
or writes only.  Bursts allow the guest I/O to spike above the limit
temporarily.
@item throttling.iops-total=@var{i},throttling.iops-read=@var{r}, throttling.iops-write=@var{w}
Specify request rate limits in requests per second, either for all request
types or for reads or writes only.
@item throttling.iops-total-max=@var{im},throttling.iops-read-max=@var{irm}, throttling.iops-write-max=@var{iwm}
Specify bursts in requests per second, either for all request types or for reads
or writes only.  Bursts allow the guest I/O to spike above the limit temporarily.
@item throttling.iops-size=@var{is}
Let every @var{is} bytes of a request count as a new request for iops
throttling purposes.
@end table

-fsdev option is used along with -device driver "virtio-9p-...".
@item -device virtio-9p-@var{type},fsdev=@var{id},mount_tag=@var{mount_tag}
Options for virtio-9p-... driver are:
@table @option
@item @var{type}
Specifies the variant to be used. Supported values are "pci", "ccw" or "device",
depending on the machine type.
@item fsdev=@var{id}
Specifies the id value specified along with -fsdev option.
@item mount_tag=@var{mount_tag}
Specifies the tag name to be used by the guest to mount this export point.
@end table

ETEXI
SRST
``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]``; \ ``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly]``; \ ``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly]``; \ ``-fsdev synth,id=id[,readonly]``
    Define a new file system device. Valid options are:

    ``local``
        Accesses to the filesystem are done by QEMU.

    ``proxy``
        Accesses to the filesystem are done by virtfs-proxy-helper(1).

    ``synth``
        Synthetic filesystem, only used by QTests.

    ``id=id``
        Specifies identifier for this device.

    ``path=path``
        Specifies the export path for the file system device. Files
        under this path will be available to the 9p client on the guest.

    ``security_model=security_model``
        Specifies the security model to be used for this export path.
        Supported security models are "passthrough", "mapped-xattr",
        "mapped-file" and "none". In "passthrough" security model, files
        are stored using the same credentials as they are created on the
        guest. This requires QEMU to run as root. In "mapped-xattr"
        security model, some of the file attributes like uid, gid, mode
        bits and link target are stored as file attributes. For
        "mapped-file" these attributes are stored in the hidden
        .virtfs\_metadata directory. Directories exported by this
        security model cannot interact with other unix tools. "none"
        security model is same as passthrough except the sever won't
        report failures if it fails to set file attributes like
        ownership. Security model is mandatory only for local fsdriver.
        Other fsdrivers (like proxy) don't take security model as a
        parameter.

    ``writeout=writeout``
        This is an optional argument. The only supported value is
        "immediate". This means that host page cache will be used to
        read and write data but write notification will be sent to the
        guest only when the data has been reported as written by the
        storage subsystem.

    ``readonly``
        Enables exporting 9p share as a readonly mount for guests. By
        default read-write access is given.

    ``socket=socket``
        Enables proxy filesystem driver to use passed socket file for
        communicating with virtfs-proxy-helper(1).

    ``sock_fd=sock_fd``
        Enables proxy filesystem driver to use passed socket descriptor
        for communicating with virtfs-proxy-helper(1). Usually a helper
        like libvirt will create socketpair and pass one of the fds as
        sock\_fd.

    ``fmode=fmode``
        Specifies the default mode for newly created files on the host.
        Works only with security models "mapped-xattr" and
        "mapped-file".

    ``dmode=dmode``
        Specifies the default mode for newly created directories on the
        host. Works only with security models "mapped-xattr" and
        "mapped-file".

    ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w``
        Specify bandwidth throttling limits in bytes per second, either
        for all request types or for reads or writes only.

    ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm``
        Specify bursts in bytes per second, either for all request types
        or for reads or writes only. Bursts allow the guest I/O to spike
        above the limit temporarily.

    ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w``
        Specify request rate limits in requests per second, either for
        all request types or for reads or writes only.

    ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm``
        Specify bursts in requests per second, either for all request
        types or for reads or writes only. Bursts allow the guest I/O to
        spike above the limit temporarily.

    ``throttling.iops-size=is``
        Let every is bytes of a request count as a new request for iops
        throttling purposes.

    -fsdev option is used along with -device driver "virtio-9p-...".

``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag``
    Options for virtio-9p-... driver are:

    ``type``
        Specifies the variant to be used. Supported values are "pci",
        "ccw" or "device", depending on the machine type.

    ``fsdev=id``
        Specifies the id value specified along with -fsdev option.

    ``mount_tag=mount_tag``
        Specifies the tag name to be used by the guest to mount this
        export point.
ERST

DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
    "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
    "        [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
    "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly]\n"
    "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly]\n"
    "-virtfs synth,mount_tag=tag[,id=id][,readonly]\n",
    QEMU_ARCH_ALL)

STEXI

@item -virtfs local,path=@var{path},mount_tag=@var{mount_tag} ,security_model=@var{security_model}[,writeout=@var{writeout}][,readonly] [,fmode=@var{fmode}][,dmode=@var{dmode}][,multidevs=@var{multidevs}]
@itemx -virtfs proxy,socket=@var{socket},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly]
@itemx -virtfs proxy,sock_fd=@var{sock_fd},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly]
@itemx -virtfs synth,mount_tag=@var{mount_tag}
@findex -virtfs

Define a new filesystem device and expose it to the guest using a virtio-9p-device. The general form of a Virtual File system pass-through options are:
@table @option
@item local
Accesses to the filesystem are done by QEMU.
@item proxy
Accesses to the filesystem are done by virtfs-proxy-helper(1).
@item synth
Synthetic filesystem, only used by QTests.
@item id=@var{id}
Specifies identifier for the filesystem device
@item path=@var{path}
Specifies the export path for the file system device. Files under
this path will be available to the 9p client on the guest.
@item security_model=@var{security_model}
Specifies the security model to be used for this export path.
Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none".
In "passthrough" security model, files are stored using the same
credentials as they are created on the guest. This requires QEMU
to run as root. In "mapped-xattr" security model, some of the file
attributes like uid, gid, mode bits and link target are stored as
file attributes. For "mapped-file" these attributes are stored in the
hidden .virtfs_metadata directory. Directories exported by this security model cannot
interact with other unix tools. "none" security model is same as
passthrough except the sever won't report failures if it fails to
set file attributes like ownership. Security model is mandatory only
for local fsdriver. Other fsdrivers (like proxy) don't take security
model as a parameter.
@item writeout=@var{writeout}
This is an optional argument. The only supported value is "immediate".
This means that host page cache will be used to read and write data but
write notification will be sent to the guest only when the data has been
reported as written by the storage subsystem.
@item readonly
Enables exporting 9p share as a readonly mount for guests. By default
read-write access is given.
@item socket=@var{socket}
Enables proxy filesystem driver to use passed socket file for
communicating with virtfs-proxy-helper(1). Usually a helper like libvirt
will create socketpair and pass one of the fds as sock_fd.
@item sock_fd
Enables proxy filesystem driver to use passed 'sock_fd' as the socket
descriptor for interfacing with virtfs-proxy-helper(1).
@item fmode=@var{fmode}
Specifies the default mode for newly created files on the host. Works only
with security models "mapped-xattr" and "mapped-file".
@item dmode=@var{dmode}
Specifies the default mode for newly created directories on the host. Works
only with security models "mapped-xattr" and "mapped-file".
@item mount_tag=@var{mount_tag}
Specifies the tag name to be used by the guest to mount this export point.
@item multidevs=@var{multidevs}
Specifies how to deal with multiple devices being shared with a 9p export.
Supported behaviours are either "remap", "forbid" or "warn". The latter is
the default behaviour on which virtfs 9p expects only one device to be
shared with the same export, and if more than one device is shared and
accessed via the same 9p export then only a warning message is logged
(once) by qemu on host side. In order to avoid file ID collisions on guest
you should either create a separate virtfs export for each device to be
shared with guests (recommended way) or you might use "remap" instead which
allows you to share multiple devices with only one export instead, which is
achieved by remapping the original inode numbers from host to guest in a
way that would prevent such collisions. Remapping inodes in such use cases
is required because the original device IDs from host are never passed and
exposed on guest. Instead all files of an export shared with virtfs always
share the same device id on guest. So two files with identical inode
numbers but from actually different devices on host would otherwise cause a
file ID collision and hence potential misbehaviours on guest. "forbid" on
the other hand assumes like "warn" that only one device is shared by the
same export, however it will not only log a warning message but also
deny access to additional devices on guest. Note though that "forbid" does
currently not block all possible file access operations (e.g. readdir()
would still return entries from other devices).
@end table
ETEXI
SRST
``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]``; \ ``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly]``; \ ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly]``; \ ``-virtfs synth,mount_tag=mount_tag``
    Define a new filesystem device and expose it to the guest using a
    virtio-9p-device. The general form of a Virtual File system
    pass-through options are:

    ``local``
        Accesses to the filesystem are done by QEMU.

    ``proxy``
        Accesses to the filesystem are done by virtfs-proxy-helper(1).

    ``synth``
        Synthetic filesystem, only used by QTests.

    ``id=id``
        Specifies identifier for the filesystem device

    ``path=path``
        Specifies the export path for the file system device. Files
        under this path will be available to the 9p client on the guest.

    ``security_model=security_model``
        Specifies the security model to be used for this export path.
        Supported security models are "passthrough", "mapped-xattr",
        "mapped-file" and "none". In "passthrough" security model, files
        are stored using the same credentials as they are created on the
        guest. This requires QEMU to run as root. In "mapped-xattr"
        security model, some of the file attributes like uid, gid, mode
        bits and link target are stored as file attributes. For
        "mapped-file" these attributes are stored in the hidden
        .virtfs\_metadata directory. Directories exported by this
        security model cannot interact with other unix tools. "none"
        security model is same as passthrough except the sever won't
        report failures if it fails to set file attributes like
        ownership. Security model is mandatory only for local fsdriver.
        Other fsdrivers (like proxy) don't take security model as a
        parameter.

    ``writeout=writeout``
        This is an optional argument. The only supported value is
        "immediate". This means that host page cache will be used to
        read and write data but write notification will be sent to the
        guest only when the data has been reported as written by the
        storage subsystem.

    ``readonly``
        Enables exporting 9p share as a readonly mount for guests. By
        default read-write access is given.

    ``socket=socket``
        Enables proxy filesystem driver to use passed socket file for
        communicating with virtfs-proxy-helper(1). Usually a helper like
        libvirt will create socketpair and pass one of the fds as
        sock\_fd.

    ``sock_fd``
        Enables proxy filesystem driver to use passed 'sock\_fd' as the
        socket descriptor for interfacing with virtfs-proxy-helper(1).

    ``fmode=fmode``
        Specifies the default mode for newly created files on the host.
        Works only with security models "mapped-xattr" and
        "mapped-file".

    ``dmode=dmode``
        Specifies the default mode for newly created directories on the
        host. Works only with security models "mapped-xattr" and
        "mapped-file".

    ``mount_tag=mount_tag``
        Specifies the tag name to be used by the guest to mount this
        export point.

    ``multidevs=multidevs``
        Specifies how to deal with multiple devices being shared with a
        9p export. Supported behaviours are either "remap", "forbid" or
        "warn". The latter is the default behaviour on which virtfs 9p
        expects only one device to be shared with the same export, and
        if more than one device is shared and accessed via the same 9p
        export then only a warning message is logged (once) by qemu on
        host side. In order to avoid file ID collisions on guest you
        should either create a separate virtfs export for each device to
        be shared with guests (recommended way) or you might use "remap"
        instead which allows you to share multiple devices with only one
        export instead, which is achieved by remapping the original
        inode numbers from host to guest in a way that would prevent
        such collisions. Remapping inodes in such use cases is required
        because the original device IDs from host are never passed and
        exposed on guest. Instead all files of an export shared with
        virtfs always share the same device id on guest. So two files
        with identical inode numbers but from actually different devices
        on host would otherwise cause a file ID collision and hence
        potential misbehaviours on guest. "forbid" on the other hand
        assumes like "warn" that only one device is shared by the same
        export, however it will not only log a warning message but also
        deny access to additional devices on guest. Note though that
        "forbid" does currently not block all possible file access
        operations (e.g. readdir() would still return entries from other
        devices).
ERST

DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
    "-iscsi [user=user][,password=password]\n"
    "       [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
    "       [,initiator-name=initiator-iqn][,id=target-iqn]\n"
    "       [,timeout=timeout]\n"
    "                iSCSI session parameters\n", QEMU_ARCH_ALL)

STEXI
@item -iscsi
@findex -iscsi
Configure iSCSI session parameters.
ETEXI
SRST
``-iscsi``
    Configure iSCSI session parameters.
ERST

STEXI
@end table
ETEXI
DEFHEADING()

DEFHEADING(USB options:)
STEXI
@table @option
ETEXI

DEF("usb", 0, QEMU_OPTION_usb,
    "-usb            enable on-board USB host controller (if not enabled by default)\n",
    QEMU_ARCH_ALL)
STEXI
@item -usb
@findex -usb
Enable USB emulation on machine types with an on-board USB host controller (if
not enabled by default).  Note that on-board USB host controllers may not
support USB 3.0.  In this case @option{-device qemu-xhci} can be used instead
on machines with PCI.
ETEXI
SRST
``-usb``
    Enable USB emulation on machine types with an on-board USB host
    controller (if not enabled by default). Note that on-board USB host
    controllers may not support USB 3.0. In this case
    ``-device qemu-xhci`` can be used instead on machines with PCI.
ERST

DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
    "-usbdevice name add the host or guest USB device 'name'\n",
    QEMU_ARCH_ALL)
STEXI

@item -usbdevice @var{devname}
@findex -usbdevice
Add the USB device @var{devname}. Note that this option is deprecated,
please use @code{-device usb-...} instead. @xref{usb_devices}.

@table @option

@item mouse
Virtual Mouse. This will override the PS/2 mouse emulation when activated.

@item tablet
Pointer device that uses absolute coordinates (like a touchscreen). This
means QEMU is able to report the mouse position without having to grab the
mouse. Also overrides the PS/2 mouse emulation when activated.

@item braille
Braille device.  This will use BrlAPI to display the braille output on a real
or fake device.

@end table
ETEXI
SRST
``-usbdevice devname``
    Add the USB device devname. Note that this option is deprecated,
    please use ``-device usb-...`` instead. See
    :ref:`usb_005fdevices`.

    ``mouse``
        Virtual Mouse. This will override the PS/2 mouse emulation when
        activated.

    ``tablet``
        Pointer device that uses absolute coordinates (like a
        touchscreen). This means QEMU is able to report the mouse
        position without having to grab the mouse. Also overrides the
        PS/2 mouse emulation when activated.

    ``braille``
        Braille device. This will use BrlAPI to display the braille
        output on a real or fake device.
ERST

STEXI
@end table
ETEXI
DEFHEADING()

DEFHEADING(Display options:)
STEXI
@table @option
ETEXI

DEF("display", HAS_ARG, QEMU_OPTION_display,
#if defined(CONFIG_SPICE)
    "-display spice-app[,gl=on|off]\n"
#endif
#if defined(CONFIG_SDL)
    "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off]\n"
    "            [,window_close=on|off][,gl=on|core|es|off]\n"
#endif
#if defined(CONFIG_GTK)
    "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
#endif
#if defined(CONFIG_VNC)
    "-display vnc=<display>[,<optargs>]\n"
#endif
#if defined(CONFIG_CURSES)
    "-display curses[,charset=<encoding>]\n"
#endif
#if defined(CONFIG_OPENGL)
    "-display egl-headless[,rendernode=<file>]\n"
#endif
    "-display none\n"
    "                select display backend type\n"
    "                The default display is equivalent to\n                "
#if defined(CONFIG_GTK)
            "\"-display gtk\"\n"
#elif defined(CONFIG_SDL)
            "\"-display sdl\"\n"
#elif defined(CONFIG_COCOA)
            "\"-display cocoa\"\n"
#elif defined(CONFIG_VNC)
            "\"-vnc localhost:0,to=99,id=default\"\n"
#else
            "\"-display none\"\n"
#endif
    , QEMU_ARCH_ALL)
STEXI
@item -display @var{type}
@findex -display
Select type of display to use. This option is a replacement for the
old style -sdl/-curses/... options. Use @code{-display help} to list
the available display types. Valid values for @var{type} are
@table @option
@item sdl
Display video output via SDL (usually in a separate graphics
window; see the SDL documentation for other possibilities).
@item curses
Display video output via curses. For graphics device models which
support a text mode, QEMU can display this output using a
curses/ncurses interface. Nothing is displayed when the graphics
device is in graphical mode or if the graphics device does not support
a text mode. Generally only the VGA device models support text mode.
The font charset used by the guest can be specified with the
@code{charset} option, for example @code{charset=CP850} for IBM CP850
encoding. The default is @code{CP437}.
@item none
Do not display video output. The guest will still see an emulated
graphics card, but its output will not be displayed to the QEMU
user. This option differs from the -nographic option in that it
only affects what is done with video output; -nographic also changes
the destination of the serial and parallel port data.
@item gtk
Display video output in a GTK window. This interface provides drop-down
menus and other UI elements to configure and control the VM during
runtime.
@item vnc
Start a VNC server on display <arg>
@item egl-headless
Offload all OpenGL operations to a local DRI device. For any graphical display,
this display needs to be paired with either VNC or SPICE displays.
@item spice-app
Start QEMU as a Spice server and launch the default Spice client
application. The Spice server will redirect the serial consoles and
QEMU monitors. (Since 4.0)
@end table
ETEXI
SRST
``-display type``
    Select type of display to use. This option is a replacement for the
    old style -sdl/-curses/... options. Use ``-display help`` to list
    the available display types. Valid values for type are

    ``sdl``
        Display video output via SDL (usually in a separate graphics
        window; see the SDL documentation for other possibilities).

    ``curses``
        Display video output via curses. For graphics device models
        which support a text mode, QEMU can display this output using a
        curses/ncurses interface. Nothing is displayed when the graphics
        device is in graphical mode or if the graphics device does not
        support a text mode. Generally only the VGA device models
        support text mode. The font charset used by the guest can be
        specified with the ``charset`` option, for example
        ``charset=CP850`` for IBM CP850 encoding. The default is
        ``CP437``.

    ``none``
        Do not display video output. The guest will still see an
        emulated graphics card, but its output will not be displayed to
        the QEMU user. This option differs from the -nographic option in
        that it only affects what is done with video output; -nographic
        also changes the destination of the serial and parallel port
        data.

    ``gtk``
        Display video output in a GTK window. This interface provides
        drop-down menus and other UI elements to configure and control
        the VM during runtime.

    ``vnc``
        Start a VNC server on display <arg>

    ``egl-headless``
        Offload all OpenGL operations to a local DRI device. For any
        graphical display, this display needs to be paired with either
        VNC or SPICE displays.

    ``spice-app``
        Start QEMU as a Spice server and launch the default Spice client
        application. The Spice server will redirect the serial consoles
        and QEMU monitors. (Since 4.0)
ERST

DEF("nographic", 0, QEMU_OPTION_nographic,
    "-nographic      disable graphical output and redirect serial I/Os to console\n",
    QEMU_ARCH_ALL)
STEXI
@item -nographic
@findex -nographic
Normally, if QEMU is compiled with graphical window support, it displays
output such as guest graphics, guest console, and the QEMU monitor in a
window. With this option, you can totally disable graphical output so
that QEMU is a simple command line application. The emulated serial port
is redirected on the console and muxed with the monitor (unless
redirected elsewhere explicitly). Therefore, you can still use QEMU to
debug a Linux kernel with a serial console. Use @key{C-a h} for help on
switching between the console and monitor.
ETEXI
SRST
``-nographic``
    Normally, if QEMU is compiled with graphical window support, it
    displays output such as guest graphics, guest console, and the QEMU
    monitor in a window. With this option, you can totally disable
    graphical output so that QEMU is a simple command line application.
    The emulated serial port is redirected on the console and muxed with
    the monitor (unless redirected elsewhere explicitly). Therefore, you
    can still use QEMU to debug a Linux kernel with a serial console.
    Use C-a h for help on switching between the console and monitor.
ERST

DEF("curses", 0, QEMU_OPTION_curses,
    "-curses         shorthand for -display curses\n",
    QEMU_ARCH_ALL)
STEXI
@item -curses
@findex -curses
Normally, if QEMU is compiled with graphical window support, it displays
output such as guest graphics, guest console, and the QEMU monitor in a
window. With this option, QEMU can display the VGA output when in text
mode using a curses/ncurses interface. Nothing is displayed in graphical
mode.
ETEXI
SRST
``-curses``
    Normally, if QEMU is compiled with graphical window support, it
    displays output such as guest graphics, guest console, and the QEMU
    monitor in a window. With this option, QEMU can display the VGA
    output when in text mode using a curses/ncurses interface. Nothing
    is displayed in graphical mode.
ERST

DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
    "-alt-grab       use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
    QEMU_ARCH_ALL)
STEXI
@item -alt-grab
@findex -alt-grab
Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that this also
affects the special keys (for fullscreen, monitor-mode switching, etc).
ETEXI
SRST
``-alt-grab``
    Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
    this also affects the special keys (for fullscreen, monitor-mode
    switching, etc).
ERST

DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
    "-ctrl-grab      use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
    QEMU_ARCH_ALL)
STEXI
@item -ctrl-grab
@findex -ctrl-grab
Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this also
affects the special keys (for fullscreen, monitor-mode switching, etc).
ETEXI
SRST
``-ctrl-grab``
    Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
    also affects the special keys (for fullscreen, monitor-mode
    switching, etc).
ERST

DEF("no-quit", 0, QEMU_OPTION_no_quit,
    "-no-quit        disable SDL window close capability\n", QEMU_ARCH_ALL)
STEXI
@item -no-quit
@findex -no-quit
Disable SDL window close capability.
ETEXI
SRST
``-no-quit``
    Disable SDL window close capability.
ERST

DEF("sdl", 0, QEMU_OPTION_sdl,
    "-sdl            shorthand for -display sdl\n", QEMU_ARCH_ALL)
STEXI
@item -sdl
@findex -sdl
Enable SDL.
ETEXI
SRST
``-sdl``
    Enable SDL.
ERST

DEF("spice", HAS_ARG, QEMU_OPTION_spice,
    "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
    "       [,x509-key-file=<file>][,x509-key-password=<file>]\n"
    "       [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
    "       [,x509-dh-key-file=<file>][,addr=addr][,ipv4|ipv6|unix]\n"
    "       [,tls-ciphers=<list>]\n"
    "       [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
    "       [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
    "       [,sasl][,password=<secret>][,disable-ticketing]\n"
    "       [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
    "       [,jpeg-wan-compression=[auto|never|always]]\n"
    "       [,zlib-glz-wan-compression=[auto|never|always]]\n"
    "       [,streaming-video=[off|all|filter]][,disable-copy-paste]\n"
    "       [,disable-agent-file-xfer][,agent-mouse=[on|off]]\n"
    "       [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
    "       [,gl=[on|off]][,rendernode=<file>]\n"
    "   enable spice\n"
    "   at least one of {port, tls-port} is mandatory\n",
    QEMU_ARCH_ALL)
STEXI
@item -spice @var{option}[,@var{option}[,...]]
@findex -spice
Enable the spice remote desktop protocol. Valid options are

@table @option

@item port=<nr>
Set the TCP port spice is listening on for plaintext channels.

@item addr=<addr>
Set the IP address spice is listening on.  Default is any address.

@item ipv4
@itemx ipv6
@itemx unix
Force using the specified IP version.

@item password=<secret>
Set the password you need to authenticate.

@item sasl
Require that the client use SASL to authenticate with the spice.
The exact choice of authentication method used is controlled from the
system / user's SASL configuration file for the 'qemu' service. This
is typically found in /etc/sasl2/qemu.conf. If running QEMU as an
unprivileged user, an environment variable SASL_CONF_PATH can be used
to make it search alternate locations for the service config.
While some SASL auth methods can also provide data encryption (eg GSSAPI),
it is recommended that SASL always be combined with the 'tls' and
'x509' settings to enable use of SSL and server certificates. This
ensures a data encryption preventing compromise of authentication
credentials.

@item disable-ticketing
Allow client connects without authentication.

@item disable-copy-paste
Disable copy paste between the client and the guest.

@item disable-agent-file-xfer
Disable spice-vdagent based file-xfer between the client and the guest.

@item tls-port=<nr>
Set the TCP port spice is listening on for encrypted channels.

@item x509-dir=<dir>
Set the x509 file directory. Expects same filenames as -vnc $display,x509=$dir

@item x509-key-file=<file>
@itemx x509-key-password=<file>
@itemx x509-cert-file=<file>
@itemx x509-cacert-file=<file>
@itemx x509-dh-key-file=<file>
The x509 file names can also be configured individually.

@item tls-ciphers=<list>
Specify which ciphers to use.

@item tls-channel=[main|display|cursor|inputs|record|playback]
@itemx plaintext-channel=[main|display|cursor|inputs|record|playback]
Force specific channel to be used with or without TLS encryption.  The
options can be specified multiple times to configure multiple
channels.  The special name "default" can be used to set the default
mode.  For channels which are not explicitly forced into one mode the
spice client is allowed to pick tls/plaintext as he pleases.

@item image-compression=[auto_glz|auto_lz|quic|glz|lz|off]
Configure image compression (lossless).
Default is auto_glz.

@item jpeg-wan-compression=[auto|never|always]
@itemx zlib-glz-wan-compression=[auto|never|always]
Configure wan image compression (lossy for slow links).
Default is auto.

@item streaming-video=[off|all|filter]
Configure video stream detection.  Default is off.

@item agent-mouse=[on|off]
Enable/disable passing mouse events via vdagent.  Default is on.

@item playback-compression=[on|off]
Enable/disable audio stream compression (using celt 0.5.1).  Default is on.

@item seamless-migration=[on|off]
Enable/disable spice seamless migration. Default is off.

@item gl=[on|off]
Enable/disable OpenGL context. Default is off.

@item rendernode=<file>
DRM render node for OpenGL rendering. If not specified, it will pick
the first available. (Since 2.9)

@end table
ETEXI
SRST
``-spice option[,option[,...]]``
    Enable the spice remote desktop protocol. Valid options are

    ``port=<nr>``
        Set the TCP port spice is listening on for plaintext channels.

    ``addr=<addr>``
        Set the IP address spice is listening on. Default is any
        address.

    ``ipv4``; \ ``ipv6``; \ ``unix``
        Force using the specified IP version.

    ``password=<secret>``
        Set the password you need to authenticate.

    ``sasl``
        Require that the client use SASL to authenticate with the spice.
        The exact choice of authentication method used is controlled
        from the system / user's SASL configuration file for the 'qemu'
        service. This is typically found in /etc/sasl2/qemu.conf. If
        running QEMU as an unprivileged user, an environment variable
        SASL\_CONF\_PATH can be used to make it search alternate
        locations for the service config. While some SASL auth methods
        can also provide data encryption (eg GSSAPI), it is recommended
        that SASL always be combined with the 'tls' and 'x509' settings
        to enable use of SSL and server certificates. This ensures a
        data encryption preventing compromise of authentication
        credentials.

    ``disable-ticketing``
        Allow client connects without authentication.

    ``disable-copy-paste``
        Disable copy paste between the client and the guest.

    ``disable-agent-file-xfer``
        Disable spice-vdagent based file-xfer between the client and the
        guest.

    ``tls-port=<nr>``
        Set the TCP port spice is listening on for encrypted channels.

    ``x509-dir=<dir>``
        Set the x509 file directory. Expects same filenames as -vnc
        $display,x509=$dir

    ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>``
        The x509 file names can also be configured individually.

    ``tls-ciphers=<list>``
        Specify which ciphers to use.

    ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]``
        Force specific channel to be used with or without TLS
        encryption. The options can be specified multiple times to
        configure multiple channels. The special name "default" can be
        used to set the default mode. For channels which are not
        explicitly forced into one mode the spice client is allowed to
        pick tls/plaintext as he pleases.

    ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]``
        Configure image compression (lossless). Default is auto\_glz.

    ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]``
        Configure wan image compression (lossy for slow links). Default
        is auto.

    ``streaming-video=[off|all|filter]``
        Configure video stream detection. Default is off.

    ``agent-mouse=[on|off]``
        Enable/disable passing mouse events via vdagent. Default is on.

    ``playback-compression=[on|off]``
        Enable/disable audio stream compression (using celt 0.5.1).
        Default is on.

    ``seamless-migration=[on|off]``
        Enable/disable spice seamless migration. Default is off.

    ``gl=[on|off]``
        Enable/disable OpenGL context. Default is off.

    ``rendernode=<file>``
        DRM render node for OpenGL rendering. If not specified, it will
        pick the first available. (Since 2.9)
ERST

DEF("portrait", 0, QEMU_OPTION_portrait,
    "-portrait       rotate graphical output 90 deg left (only PXA LCD)\n",
    QEMU_ARCH_ALL)
STEXI
@item -portrait
@findex -portrait
Rotate graphical output 90 deg left (only PXA LCD).
ETEXI
SRST
``-portrait``
    Rotate graphical output 90 deg left (only PXA LCD).
ERST

DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
    "-rotate <deg>   rotate graphical output some deg left (only PXA LCD)\n",
    QEMU_ARCH_ALL)
STEXI
@item -rotate @var{deg}
@findex -rotate
Rotate graphical output some deg left (only PXA LCD).
ETEXI
SRST
``-rotate deg``
    Rotate graphical output some deg left (only PXA LCD).
ERST

DEF("vga", HAS_ARG, QEMU_OPTION_vga,
    "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
    "                select video card type\n", QEMU_ARCH_ALL)
STEXI
@item -vga @var{type}
@findex -vga
Select type of VGA card to emulate. Valid values for @var{type} are
@table @option
@item cirrus
Cirrus Logic GD5446 Video card. All Windows versions starting from
Windows 95 should recognize and use this graphic card. For optimal
performances, use 16 bit color depth in the guest and the host OS.
(This card was the default before QEMU 2.2)
@item std
Standard VGA card with Bochs VBE extensions.  If your guest OS
supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if you want
to use high resolution modes (>= 1280x1024x16) then you should use
this option. (This card is the default since QEMU 2.2)
@item vmware
VMWare SVGA-II compatible adapter. Use it if you have sufficiently
recent XFree86/XOrg server or Windows guest with a driver for this
card.
@item qxl
QXL paravirtual graphic card.  It is VGA compatible (including VESA
2.0 VBE support).  Works best with qxl guest drivers installed though.
Recommended choice when using the spice protocol.
@item tcx
(sun4m only) Sun TCX framebuffer. This is the default framebuffer for
sun4m machines and offers both 8-bit and 24-bit colour depths at a
fixed resolution of 1024x768.
@item cg3
(sun4m only) Sun cgthree framebuffer. This is a simple 8-bit framebuffer
for sun4m machines available in both 1024x768 (OpenBIOS) and 1152x900 (OBP)
resolutions aimed at people wishing to run older Solaris versions.
@item virtio
Virtio VGA card.
@item none
Disable VGA card.
@end table
ETEXI
SRST
``-vga type``
    Select type of VGA card to emulate. Valid values for type are

    ``cirrus``
        Cirrus Logic GD5446 Video card. All Windows versions starting
        from Windows 95 should recognize and use this graphic card. For
        optimal performances, use 16 bit color depth in the guest and
        the host OS. (This card was the default before QEMU 2.2)

    ``std``
        Standard VGA card with Bochs VBE extensions. If your guest OS
        supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
        you want to use high resolution modes (>= 1280x1024x16) then you
        should use this option. (This card is the default since QEMU
        2.2)

    ``vmware``
        VMWare SVGA-II compatible adapter. Use it if you have
        sufficiently recent XFree86/XOrg server or Windows guest with a
        driver for this card.

    ``qxl``
        QXL paravirtual graphic card. It is VGA compatible (including
        VESA 2.0 VBE support). Works best with qxl guest drivers
        installed though. Recommended choice when using the spice
        protocol.

    ``tcx``
        (sun4m only) Sun TCX framebuffer. This is the default
        framebuffer for sun4m machines and offers both 8-bit and 24-bit
        colour depths at a fixed resolution of 1024x768.

    ``cg3``
        (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit
        framebuffer for sun4m machines available in both 1024x768
        (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people
        wishing to run older Solaris versions.

    ``virtio``
        Virtio VGA card.

    ``none``
        Disable VGA card.
ERST

DEF("full-screen", 0, QEMU_OPTION_full_screen,
    "-full-screen    start in full screen\n", QEMU_ARCH_ALL)
STEXI
@item -full-screen
@findex -full-screen
Start in full screen.
ETEXI
SRST
``-full-screen``
    Start in full screen.
ERST

DEF("g", HAS_ARG, QEMU_OPTION_g ,
    "-g WxH[xDEPTH]  Set the initial graphical resolution and depth\n",
    QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K)
STEXI
@item -g @var{width}x@var{height}[x@var{depth}]
@findex -g
Set the initial graphical resolution and depth (PPC, SPARC only).

For PPC the default is 800x600x32.

For SPARC with the TCX graphics device, the default is 1024x768x8 with the
option of 1024x768x24. For cgthree, the default is 1024x768x8 with the option
of 1152x900x8 for people who wish to use OBP.

ETEXI
SRST
``-g widthxheight[xdepth]``
    Set the initial graphical resolution and depth (PPC, SPARC only).

    For PPC the default is 800x600x32.

    For SPARC with the TCX graphics device, the default is 1024x768x8
    with the option of 1024x768x24. For cgthree, the default is
    1024x768x8 with the option of 1152x900x8 for people who wish to use
    OBP.
ERST

DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
    "-vnc <display>  shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
STEXI
@item -vnc @var{display}[,@var{option}[,@var{option}[,...]]]
@findex -vnc
Normally, if QEMU is compiled with graphical window support, it displays
output such as guest graphics, guest console, and the QEMU monitor in a
window. With this option, you can have QEMU listen on VNC display
@var{display} and redirect the VGA display over the VNC session. It is
very useful to enable the usb tablet device when using this option
(option @option{-device usb-tablet}). When using the VNC display, you
must use the @option{-k} parameter to set the keyboard layout if you are
not using en-us. Valid syntax for the @var{display} is

@table @option

@item to=@var{L}

With this option, QEMU will try next available VNC @var{display}s, until the
number @var{L}, if the origianlly defined "-vnc @var{display}" is not
available, e.g. port 5900+@var{display} is already used by another
application. By default, to=0.

@item @var{host}:@var{d}

TCP connections will only be allowed from @var{host} on display @var{d}.
By convention the TCP port is 5900+@var{d}. Optionally, @var{host} can
be omitted in which case the server will accept connections from any host.

@item unix:@var{path}

Connections will be allowed over UNIX domain sockets where @var{path} is the
location of a unix socket to listen for connections on.

@item none

VNC is initialized but not started. The monitor @code{change} command
can be used to later start the VNC server.

@end table

Following the @var{display} value there may be one or more @var{option} flags
separated by commas. Valid options are

@table @option

@item reverse

Connect to a listening VNC client via a ``reverse'' connection. The
client is specified by the @var{display}. For reverse network
connections (@var{host}:@var{d},@code{reverse}), the @var{d} argument
is a TCP port number, not a display number.

@item websocket

Opens an additional TCP listening port dedicated to VNC Websocket connections.
If a bare @var{websocket} option is given, the Websocket port is
5700+@var{display}. An alternative port can be specified with the
syntax @code{websocket}=@var{port}.

If @var{host} is specified connections will only be allowed from this host.
It is possible to control the websocket listen address independently, using
the syntax @code{websocket}=@var{host}:@var{port}.

If no TLS credentials are provided, the websocket connection runs in
unencrypted mode. If TLS credentials are provided, the websocket connection
requires encrypted client connections.

@item password

Require that password based authentication is used for client connections.

The password must be set separately using the @code{set_password} command in
the @ref{pcsys_monitor}. The syntax to change your password is:
@code{set_password <protocol> <password>} where <protocol> could be either
"vnc" or "spice".

If you would like to change <protocol> password expiration, you should use
@code{expire_password <protocol> <expiration-time>} where expiration time could
be one of the following options: now, never, +seconds or UNIX time of
expiration, e.g. +60 to make password expire in 60 seconds, or 1335196800
to make password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for this
date and time).

You can also use keywords "now" or "never" for the expiration time to
allow <protocol> password to expire immediately or never expire.

@item tls-creds=@var{ID}

Provides the ID of a set of TLS credentials to use to secure the
VNC server. They will apply to both the normal VNC server socket
and the websocket socket (if enabled). Setting TLS credentials
will cause the VNC server socket to enable the VeNCrypt auth
mechanism.  The credentials should have been previously created
using the @option{-object tls-creds} argument.

@item tls-authz=@var{ID}

Provides the ID of the QAuthZ authorization object against which
the client's x509 distinguished name will validated. This object is
only resolved at time of use, so can be deleted and recreated on the
fly while the VNC server is active. If missing, it will default
to denying access.

@item sasl

Require that the client use SASL to authenticate with the VNC server.
The exact choice of authentication method used is controlled from the
system / user's SASL configuration file for the 'qemu' service. This
is typically found in /etc/sasl2/qemu.conf. If running QEMU as an
unprivileged user, an environment variable SASL_CONF_PATH can be used
to make it search alternate locations for the service config.
While some SASL auth methods can also provide data encryption (eg GSSAPI),
it is recommended that SASL always be combined with the 'tls' and
'x509' settings to enable use of SSL and server certificates. This
ensures a data encryption preventing compromise of authentication
credentials. See the @ref{vnc_security} section for details on using
SASL authentication.

@item sasl-authz=@var{ID}

Provides the ID of the QAuthZ authorization object against which
the client's SASL username will validated. This object is
only resolved at time of use, so can be deleted and recreated on the
fly while the VNC server is active. If missing, it will default
to denying access.

@item acl

Legacy method for enabling authorization of clients against the
x509 distinguished name and SASL username. It results in the creation
of two @code{authz-list} objects with IDs of @code{vnc.username} and
@code{vnc.x509dname}. The rules for these objects must be configured
with the HMP ACL commands.

This option is deprecated and should no longer be used. The new
@option{sasl-authz} and @option{tls-authz} options are a
replacement.

@item lossy

Enable lossy compression methods (gradient, JPEG, ...). If this
option is set, VNC client may receive lossy framebuffer updates
depending on its encoding settings. Enabling this option can save
a lot of bandwidth at the expense of quality.

@item non-adaptive

Disable adaptive encodings. Adaptive encodings are enabled by default.
An adaptive encoding will try to detect frequently updated screen regions,
and send updates in these regions using a lossy encoding (like JPEG).
This can be really helpful to save bandwidth when playing videos. Disabling
adaptive encodings restores the original static behavior of encodings
like Tight.

@item share=[allow-exclusive|force-shared|ignore]

Set display sharing policy.  'allow-exclusive' allows clients to ask
for exclusive access.  As suggested by the rfb spec this is
implemented by dropping other connections.  Connecting multiple
clients in parallel requires all clients asking for a shared session
(vncviewer: -shared switch).  This is the default.  'force-shared'
disables exclusive client access.  Useful for shared desktop sessions,
where you don't want someone forgetting specify -shared disconnect
everybody else.  'ignore' completely ignores the shared flag and
allows everybody connect unconditionally.  Doesn't conform to the rfb
spec but is traditional QEMU behavior.

@item key-delay-ms

Set keyboard delay, for key down and key up events, in milliseconds.
Default is 10.  Keyboards are low-bandwidth devices, so this slowdown
can help the device and guest to keep up and not lose events in case
events are arriving in bulk.  Possible causes for the latter are flaky
network connections, or scripts for automated testing.

@item audiodev=@var{audiodev}

Use the specified @var{audiodev} when the VNC client requests audio
transmission. When not using an -audiodev argument, this option must
be omitted, otherwise is must be present and specify a valid audiodev.

@end table
ETEXI
SRST
``-vnc display[,option[,option[,...]]]``
    Normally, if QEMU is compiled with graphical window support, it
    displays output such as guest graphics, guest console, and the QEMU
    monitor in a window. With this option, you can have QEMU listen on
    VNC display display and redirect the VGA display over the VNC
    session. It is very useful to enable the usb tablet device when
    using this option (option ``-device usb-tablet``). When using the
    VNC display, you must use the ``-k`` parameter to set the keyboard
    layout if you are not using en-us. Valid syntax for the display is

    ``to=L``
        With this option, QEMU will try next available VNC displays,
        until the number L, if the origianlly defined "-vnc display" is
        not available, e.g. port 5900+display is already used by another
        application. By default, to=0.

    ``host:d``
        TCP connections will only be allowed from host on display d. By
        convention the TCP port is 5900+d. Optionally, host can be
        omitted in which case the server will accept connections from
        any host.

    ``unix:path``
        Connections will be allowed over UNIX domain sockets where path
        is the location of a unix socket to listen for connections on.

    ``none``
        VNC is initialized but not started. The monitor ``change``
        command can be used to later start the VNC server.

    Following the display value there may be one or more option flags
    separated by commas. Valid options are

    ``reverse``
        Connect to a listening VNC client via a "reverse" connection.
        The client is specified by the display. For reverse network
        connections (host:d,``reverse``), the d argument is a TCP port
        number, not a display number.

    ``websocket``
        Opens an additional TCP listening port dedicated to VNC
        Websocket connections. If a bare websocket option is given, the
        Websocket port is 5700+display. An alternative port can be
        specified with the syntax ``websocket``\ =port.

        If host is specified connections will only be allowed from this
        host. It is possible to control the websocket listen address
        independently, using the syntax ``websocket``\ =host:port.

        If no TLS credentials are provided, the websocket connection
        runs in unencrypted mode. If TLS credentials are provided, the
        websocket connection requires encrypted client connections.

    ``password``
        Require that password based authentication is used for client
        connections.

        The password must be set separately using the ``set_password``
        command in the :ref:`pcsys_005fmonitor`. The
        syntax to change your password is:
        ``set_password <protocol> <password>`` where <protocol> could be
        either "vnc" or "spice".

        If you would like to change <protocol> password expiration, you
        should use ``expire_password <protocol> <expiration-time>``
        where expiration time could be one of the following options:
        now, never, +seconds or UNIX time of expiration, e.g. +60 to
        make password expire in 60 seconds, or 1335196800 to make
        password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for
        this date and time).

        You can also use keywords "now" or "never" for the expiration
        time to allow <protocol> password to expire immediately or never
        expire.

    ``tls-creds=ID``
        Provides the ID of a set of TLS credentials to use to secure the
        VNC server. They will apply to both the normal VNC server socket
        and the websocket socket (if enabled). Setting TLS credentials
        will cause the VNC server socket to enable the VeNCrypt auth
        mechanism. The credentials should have been previously created
        using the ``-object tls-creds`` argument.

    ``tls-authz=ID``
        Provides the ID of the QAuthZ authorization object against which
        the client's x509 distinguished name will validated. This object
        is only resolved at time of use, so can be deleted and recreated
        on the fly while the VNC server is active. If missing, it will
        default to denying access.

    ``sasl``
        Require that the client use SASL to authenticate with the VNC
        server. The exact choice of authentication method used is
        controlled from the system / user's SASL configuration file for
        the 'qemu' service. This is typically found in
        /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
        an environment variable SASL\_CONF\_PATH can be used to make it
        search alternate locations for the service config. While some
        SASL auth methods can also provide data encryption (eg GSSAPI),
        it is recommended that SASL always be combined with the 'tls'
        and 'x509' settings to enable use of SSL and server
        certificates. This ensures a data encryption preventing
        compromise of authentication credentials. See the
        :ref:`vnc_005fsecurity` section for details on
        using SASL authentication.

    ``sasl-authz=ID``
        Provides the ID of the QAuthZ authorization object against which
        the client's SASL username will validated. This object is only
        resolved at time of use, so can be deleted and recreated on the
        fly while the VNC server is active. If missing, it will default
        to denying access.

    ``acl``
        Legacy method for enabling authorization of clients against the
        x509 distinguished name and SASL username. It results in the
        creation of two ``authz-list`` objects with IDs of
        ``vnc.username`` and ``vnc.x509dname``. The rules for these
        objects must be configured with the HMP ACL commands.

        This option is deprecated and should no longer be used. The new
        ``sasl-authz`` and ``tls-authz`` options are a replacement.

    ``lossy``
        Enable lossy compression methods (gradient, JPEG, ...). If this
        option is set, VNC client may receive lossy framebuffer updates
        depending on its encoding settings. Enabling this option can
        save a lot of bandwidth at the expense of quality.

    ``non-adaptive``
        Disable adaptive encodings. Adaptive encodings are enabled by
        default. An adaptive encoding will try to detect frequently
        updated screen regions, and send updates in these regions using
        a lossy encoding (like JPEG). This can be really helpful to save
        bandwidth when playing videos. Disabling adaptive encodings
        restores the original static behavior of encodings like Tight.

    ``share=[allow-exclusive|force-shared|ignore]``
        Set display sharing policy. 'allow-exclusive' allows clients to
        ask for exclusive access. As suggested by the rfb spec this is
        implemented by dropping other connections. Connecting multiple
        clients in parallel requires all clients asking for a shared
        session (vncviewer: -shared switch). This is the default.
        'force-shared' disables exclusive client access. Useful for
        shared desktop sessions, where you don't want someone forgetting
        specify -shared disconnect everybody else. 'ignore' completely
        ignores the shared flag and allows everybody connect
        unconditionally. Doesn't conform to the rfb spec but is
        traditional QEMU behavior.

    ``key-delay-ms``
        Set keyboard delay, for key down and key up events, in
        milliseconds. Default is 10. Keyboards are low-bandwidth
        devices, so this slowdown can help the device and guest to keep
        up and not lose events in case events are arriving in bulk.
        Possible causes for the latter are flaky network connections, or
        scripts for automated testing.

    ``audiodev=audiodev``
        Use the specified audiodev when the VNC client requests audio
        transmission. When not using an -audiodev argument, this option
        must be omitted, otherwise is must be present and specify a
        valid audiodev.
ERST

STEXI
@end table
ETEXI
ARCHHEADING(, QEMU_ARCH_I386)

ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
STEXI
@table @option
ETEXI

DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
    "-win2k-hack     use it when installing Windows 2000 to avoid a disk full bug\n",
    QEMU_ARCH_I386)
STEXI
@item -win2k-hack
@findex -win2k-hack
Use it when installing Windows 2000 to avoid a disk full bug. After
Windows 2000 is installed, you no longer need this option (this option
slows down the IDE transfers).
ETEXI
SRST
``-win2k-hack``
    Use it when installing Windows 2000 to avoid a disk full bug. After
    Windows 2000 is installed, you no longer need this option (this
    option slows down the IDE transfers).
ERST

DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
    "-no-fd-bootchk  disable boot signature checking for floppy disks\n",
    QEMU_ARCH_I386)
STEXI
@item -no-fd-bootchk
@findex -no-fd-bootchk
Disable boot signature checking for floppy disks in BIOS. May
be needed to boot from old floppy disks.
ETEXI
SRST
``-no-fd-bootchk``
    Disable boot signature checking for floppy disks in BIOS. May be
    needed to boot from old floppy disks.
ERST

DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
           "-no-acpi        disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
STEXI
@item -no-acpi
@findex -no-acpi
Disable ACPI (Advanced Configuration and Power Interface) support. Use
it if your guest OS complains about ACPI problems (PC target machine
only).
ETEXI
SRST
``-no-acpi``
    Disable ACPI (Advanced Configuration and Power Interface) support.
    Use it if your guest OS complains about ACPI problems (PC target
    machine only).
ERST

DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
    "-no-hpet        disable HPET\n", QEMU_ARCH_I386)
STEXI
@item -no-hpet
@findex -no-hpet
Disable HPET support.
ETEXI
SRST
``-no-hpet``
    Disable HPET support.
ERST

DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
    "-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n][,asl_compiler_id=str][,asl_compiler_rev=n][,{data|file}=file1[:file2]...]\n"
    "                ACPI table description\n", QEMU_ARCH_I386)
STEXI
@item -acpitable [sig=@var{str}][,rev=@var{n}][,oem_id=@var{str}][,oem_table_id=@var{str}][,oem_rev=@var{n}] [,asl_compiler_id=@var{str}][,asl_compiler_rev=@var{n}][,data=@var{file1}[:@var{file2}]...]
@findex -acpitable
Add ACPI table with specified header fields and context from specified files.
For file=, take whole ACPI table from the specified files, including all
ACPI headers (possible overridden by other options).
For data=, only data
portion of the table is used, all header information is specified in the
command line.
If a SLIC table is supplied to QEMU, then the SLIC's oem_id and oem_table_id
fields will override the same in the RSDT and the FADT (a.k.a. FACP), in order
to ensure the field matches required by the Microsoft SLIC spec and the ACPI
spec.
ETEXI
SRST
``-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n] [,asl_compiler_id=str][,asl_compiler_rev=n][,data=file1[:file2]...]``
    Add ACPI table with specified header fields and context from
    specified files. For file=, take whole ACPI table from the specified
    files, including all ACPI headers (possible overridden by other
    options). For data=, only data portion of the table is used, all
    header information is specified in the command line. If a SLIC table
    is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
    fields will override the same in the RSDT and the FADT (a.k.a.
    FACP), in order to ensure the field matches required by the
    Microsoft SLIC spec and the ACPI spec.
ERST

DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
    "-smbios file=binary\n"
    "                load SMBIOS entry from binary file\n"
    "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
    "              [,uefi=on|off]\n"
    "                specify SMBIOS type 0 fields\n"
    "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
    "              [,uuid=uuid][,sku=str][,family=str]\n"
    "                specify SMBIOS type 1 fields\n"
    "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
    "              [,asset=str][,location=str]\n"
    "                specify SMBIOS type 2 fields\n"
    "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
    "              [,sku=str]\n"
    "                specify SMBIOS type 3 fields\n"
    "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
    "              [,asset=str][,part=str]\n"
    "                specify SMBIOS type 4 fields\n"
    "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
    "               [,asset=str][,part=str][,speed=%d]\n"
    "                specify SMBIOS type 17 fields\n",
    QEMU_ARCH_I386 | QEMU_ARCH_ARM)
STEXI
@item -smbios file=@var{binary}
@findex -smbios
Load SMBIOS entry from binary file.

@item -smbios type=0[,vendor=@var{str}][,version=@var{str}][,date=@var{str}][,release=@var{%d.%d}][,uefi=on|off]
Specify SMBIOS type 0 fields

@item -smbios type=1[,manufacturer=@var{str}][,product=@var{str}][,version=@var{str}][,serial=@var{str}][,uuid=@var{uuid}][,sku=@var{str}][,family=@var{str}]
Specify SMBIOS type 1 fields

@item -smbios type=2[,manufacturer=@var{str}][,product=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,location=@var{str}]
Specify SMBIOS type 2 fields

@item -smbios type=3[,manufacturer=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,sku=@var{str}]
Specify SMBIOS type 3 fields

@item -smbios type=4[,sock_pfx=@var{str}][,manufacturer=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,part=@var{str}]
Specify SMBIOS type 4 fields

@item -smbios type=17[,loc_pfx=@var{str}][,bank=@var{str}][,manufacturer=@var{str}][,serial=@var{str}][,asset=@var{str}][,part=@var{str}][,speed=@var{%d}]
Specify SMBIOS type 17 fields
ETEXI
SRST
``-smbios file=binary``
    Load SMBIOS entry from binary file.

``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]``
    Specify SMBIOS type 0 fields

``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]``
    Specify SMBIOS type 1 fields

``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]``
    Specify SMBIOS type 2 fields

``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
    Specify SMBIOS type 3 fields

``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]``
    Specify SMBIOS type 4 fields

``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]``
    Specify SMBIOS type 17 fields
ERST

STEXI
@end table
ETEXI
DEFHEADING()

DEFHEADING(Network options:)
STEXI
@table @option
ETEXI

DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
#ifdef CONFIG_SLIRP
    "-netdev user,id=str[,ipv4[=on|off]][,net=addr[/mask]][,host=addr]\n"
    "         [,ipv6[=on|off]][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
    "         [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
    "         [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
    "         [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
#ifndef _WIN32
                                             "[,smb=dir[,smbserver=addr]]\n"
#endif
    "                configure a user mode network backend with ID 'str',\n"
    "                its DHCP server and optional services\n"
#endif
#ifdef _WIN32
    "-netdev tap,id=str,ifname=name\n"
    "                configure a host TAP network backend with ID 'str'\n"
#else
    "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
    "         [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
    "         [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
    "         [,poll-us=n]\n"
    "                configure a host TAP network backend with ID 'str'\n"
    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
    "                use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
    "                to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
    "                to deconfigure it\n"
    "                use '[down]script=no' to disable script execution\n"
    "                use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
    "                configure it\n"
    "                use 'fd=h' to connect to an already opened TAP interface\n"
    "                use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
    "                use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
    "                default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
    "                use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
    "                use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
    "                use vhost=on to enable experimental in kernel accelerator\n"
    "                    (only has effect for virtio guests which use MSIX)\n"
    "                use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
    "                use 'vhostfd=h' to connect to an already opened vhost net device\n"
    "                use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
    "                use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
    "                use 'poll-us=n' to speciy the maximum number of microseconds that could be\n"
    "                spent on busy polling for vhost net\n"
    "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
    "                configure a host TAP network backend with ID 'str' that is\n"
    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
    "                using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
#endif
#ifdef __linux__
    "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
    "         [,rxsession=rxsession],txsession=txsession[,ipv6=on/off][,udp=on/off]\n"
    "         [,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie]\n"
    "         [,rxcookie=rxcookie][,offset=offset]\n"
    "                configure a network backend with ID 'str' connected to\n"
    "                an Ethernet over L2TPv3 pseudowire.\n"
    "                Linux kernel 3.3+ as well as most routers can talk\n"
    "                L2TPv3. This transport allows connecting a VM to a VM,\n"
    "                VM to a router and even VM to Host. It is a nearly-universal\n"
    "                standard (RFC3931). Note - this implementation uses static\n"
    "                pre-configured tunnels (same as the Linux kernel).\n"
    "                use 'src=' to specify source address\n"
    "                use 'dst=' to specify destination address\n"
    "                use 'udp=on' to specify udp encapsulation\n"
    "                use 'srcport=' to specify source udp port\n"
    "                use 'dstport=' to specify destination udp port\n"
    "                use 'ipv6=on' to force v6\n"
    "                L2TPv3 uses cookies to prevent misconfiguration as\n"
    "                well as a weak security measure\n"
    "                use 'rxcookie=0x012345678' to specify a rxcookie\n"
    "                use 'txcookie=0x012345678' to specify a txcookie\n"
    "                use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
    "                use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
    "                use 'pincounter=on' to work around broken counter handling in peer\n"
    "                use 'offset=X' to add an extra offset between header and data\n"
#endif
    "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
    "                configure a network backend to connect to another network\n"
    "                using a socket connection\n"
    "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
    "                configure a network backend to connect to a multicast maddr and port\n"
    "                use 'localaddr=addr' to specify the host address to send packets from\n"
    "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
    "                configure a network backend to connect to another network\n"
    "                using an UDP tunnel\n"
#ifdef CONFIG_VDE
    "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
    "                configure a network backend to connect to port 'n' of a vde switch\n"
    "                running on host and listening for incoming connections on 'socketpath'.\n"
    "                Use group 'groupname' and mode 'octalmode' to change default\n"
    "                ownership and permissions for communication port.\n"
#endif
#ifdef CONFIG_NETMAP
    "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
    "                attach to the existing netmap-enabled network interface 'name', or to a\n"
    "                VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
    "                netmap device, defaults to '/dev/netmap')\n"
#endif
#ifdef CONFIG_POSIX
    "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
    "                configure a vhost-user network, backed by a chardev 'dev'\n"
#endif
    "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
    "                configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
DEF("nic", HAS_ARG, QEMU_OPTION_nic,
    "-nic [tap|bridge|"
#ifdef CONFIG_SLIRP
    "user|"
#endif
#ifdef __linux__
    "l2tpv3|"
#endif
#ifdef CONFIG_VDE
    "vde|"
#endif
#ifdef CONFIG_NETMAP
    "netmap|"
#endif
#ifdef CONFIG_POSIX
    "vhost-user|"
#endif
    "socket][,option][,...][mac=macaddr]\n"
    "                initialize an on-board / default host NIC (using MAC address\n"
    "                macaddr) and connect it to the given host network backend\n"
    "-nic none       use it alone to have zero network devices (the default is to\n"
    "                provided a 'user' network connection)\n",
    QEMU_ARCH_ALL)
DEF("net", HAS_ARG, QEMU_OPTION_net,
    "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
    "                configure or create an on-board (or machine default) NIC and\n"
    "                connect it to hub 0 (please use -nic unless you need a hub)\n"
    "-net ["
#ifdef CONFIG_SLIRP
    "user|"
#endif
    "tap|"
    "bridge|"
#ifdef CONFIG_VDE
    "vde|"
#endif
#ifdef CONFIG_NETMAP
    "netmap|"
#endif
    "socket][,option][,option][,...]\n"
    "                old way to initialize a host network interface\n"
    "                (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
STEXI
@item -nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]
@findex -nic
This option is a shortcut for configuring both the on-board (default) guest
NIC hardware and the host network backend in one go. The host backend options
are the same as with the corresponding @option{-netdev} options below.
The guest NIC model can be set with @option{model=@var{modelname}}.
Use @option{model=help} to list the available device types.
The hardware MAC address can be set with @option{mac=@var{macaddr}}.

The following two example do exactly the same, to show how @option{-nic} can
be used to shorten the command line length:
@example
@value{qemu_system} -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
@value{qemu_system} -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
@end example

@item -nic none
Indicate that no network devices should be configured. It is used to override
the default configuration (default NIC with ``user'' host network backend)
which is activated if no other networking options are provided.

@item -netdev user,id=@var{id}[,@var{option}][,@var{option}][,...]
@findex -netdev
Configure user mode host network backend which requires no administrator
privilege to run. Valid options are:

@table @option
@item id=@var{id}
Assign symbolic name for use in monitor commands.

@item ipv4=on|off and ipv6=on|off
Specify that either IPv4 or IPv6 must be enabled. If neither is specified
both protocols are enabled.

@item net=@var{addr}[/@var{mask}]
Set IP network address the guest will see. Optionally specify the netmask,
either in the form a.b.c.d or as number of valid top-most bits. Default is
10.0.2.0/24.

@item host=@var{addr}
Specify the guest-visible address of the host. Default is the 2nd IP in the
guest network, i.e. x.x.x.2.

@item ipv6-net=@var{addr}[/@var{int}]
Set IPv6 network address the guest will see (default is fec0::/64). The
network prefix is given in the usual hexadecimal IPv6 address
notation. The prefix size is optional, and is given as the number of
valid top-most bits (default is 64).

@item ipv6-host=@var{addr}
Specify the guest-visible IPv6 address of the host. Default is the 2nd IPv6 in
the guest network, i.e. xxxx::2.

@item restrict=on|off
If this option is enabled, the guest will be isolated, i.e. it will not be
able to contact the host and no guest IP packets will be routed over the host
to the outside. This option does not affect any explicitly set forwarding rules.

@item hostname=@var{name}
Specifies the client hostname reported by the built-in DHCP server.

@item dhcpstart=@var{addr}
Specify the first of the 16 IPs the built-in DHCP server can assign. Default
is the 15th to 31st IP in the guest network, i.e. x.x.x.15 to x.x.x.31.

@item dns=@var{addr}
Specify the guest-visible address of the virtual nameserver. The address must
be different from the host address. Default is the 3rd IP in the guest network,
i.e. x.x.x.3.

@item ipv6-dns=@var{addr}
Specify the guest-visible address of the IPv6 virtual nameserver. The address
must be different from the host address. Default is the 3rd IP in the guest
network, i.e. xxxx::3.

@item dnssearch=@var{domain}
Provides an entry for the domain-search list sent by the built-in
DHCP server. More than one domain suffix can be transmitted by specifying
this option multiple times. If supported, this will cause the guest to
automatically try to append the given domain suffix(es) in case a domain name
can not be resolved.

Example:
@example
@value{qemu_system} -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
@end example

@item domainname=@var{domain}
Specifies the client domain name reported by the built-in DHCP server.

@item tftp=@var{dir}
When using the user mode network stack, activate a built-in TFTP
server. The files in @var{dir} will be exposed as the root of a TFTP server.
The TFTP client on the guest must be configured in binary mode (use the command
@code{bin} of the Unix TFTP client).

@item tftp-server-name=@var{name}
In BOOTP reply, broadcast @var{name} as the "TFTP server name" (RFC2132 option
66). This can be used to advise the guest to load boot files or configurations
from a different server than the host address.

@item bootfile=@var{file}
When using the user mode network stack, broadcast @var{file} as the BOOTP
filename. In conjunction with @option{tftp}, this can be used to network boot
a guest from a local directory.

Example (using pxelinux):
@example
@value{qemu_system} -hda linux.img -boot n -device e1000,netdev=n1 \
    -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
@end example

@item smb=@var{dir}[,smbserver=@var{addr}]
When using the user mode network stack, activate a built-in SMB
server so that Windows OSes can access to the host files in @file{@var{dir}}
transparently. The IP address of the SMB server can be set to @var{addr}. By
default the 4th IP in the guest network is used, i.e. x.x.x.4.

In the guest Windows OS, the line:
@example
10.0.2.4 smbserver
@end example
must be added in the file @file{C:\WINDOWS\LMHOSTS} (for windows 9x/Me)
or @file{C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS} (Windows NT/2000).

Then @file{@var{dir}} can be accessed in @file{\\smbserver\qemu}.

Note that a SAMBA server must be installed on the host OS.

@item hostfwd=[tcp|udp]:[@var{hostaddr}]:@var{hostport}-[@var{guestaddr}]:@var{guestport}
Redirect incoming TCP or UDP connections to the host port @var{hostport} to
the guest IP address @var{guestaddr} on guest port @var{guestport}. If
@var{guestaddr} is not specified, its value is x.x.x.15 (default first address
given by the built-in DHCP server). By specifying @var{hostaddr}, the rule can
be bound to a specific host interface. If no connection type is set, TCP is
used. This option can be given multiple times.

For example, to redirect host X11 connection from screen 1 to guest
screen 0, use the following:

@example
# on the host
@value{qemu_system} -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
# this host xterm should open in the guest X11 server
xterm -display :1
@end example

To redirect telnet connections from host port 5555 to telnet port on
the guest, use the following:

@example
# on the host
@value{qemu_system} -nic user,hostfwd=tcp::5555-:23
telnet localhost 5555
@end example

Then when you use on the host @code{telnet localhost 5555}, you
connect to the guest telnet server.

@item guestfwd=[tcp]:@var{server}:@var{port}-@var{dev}
@itemx guestfwd=[tcp]:@var{server}:@var{port}-@var{cmd:command}
Forward guest TCP connections to the IP address @var{server} on port @var{port}
to the character device @var{dev} or to a program executed by @var{cmd:command}
which gets spawned for each connection. This option can be given multiple times.

You can either use a chardev directly and have that one used throughout QEMU's
lifetime, like in the following example:

@example
# open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
# the guest accesses it
@value{qemu_system} -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
@end example

Or you can execute a command on every TCP connection established by the guest,
so that QEMU behaves similar to an inetd process for that virtual server:

@example
# call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
# and connect the TCP stream to its stdin/stdout
@value{qemu_system} -nic  'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
@end example

@end table

@item -netdev tap,id=@var{id}[,fd=@var{h}][,ifname=@var{name}][,script=@var{file}][,downscript=@var{dfile}][,br=@var{bridge}][,helper=@var{helper}]
Configure a host TAP network backend with ID @var{id}.

Use the network script @var{file} to configure it and the network script
@var{dfile} to deconfigure it. If @var{name} is not provided, the OS
automatically provides one. The default network configure script is
@file{/etc/qemu-ifup} and the default network deconfigure script is
@file{/etc/qemu-ifdown}. Use @option{script=no} or @option{downscript=no}
to disable script execution.

If running QEMU as an unprivileged user, use the network helper
@var{helper} to configure the TAP interface and attach it to the bridge.
The default network helper executable is @file{/path/to/qemu-bridge-helper}
and the default bridge device is @file{br0}.

@option{fd}=@var{h} can be used to specify the handle of an already
opened host TAP interface.

Examples:

@example
#launch a QEMU instance with the default network script
@value{qemu_system} linux.img -nic tap
@end example

@example
#launch a QEMU instance with two NICs, each one connected
#to a TAP device
@value{qemu_system} linux.img \
        -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \
        -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
@end example

@example
#launch a QEMU instance with the default network helper to
#connect a TAP device to bridge br0
@value{qemu_system} linux.img -device virtio-net-pci,netdev=n1 \
        -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
@end example

@item -netdev bridge,id=@var{id}[,br=@var{bridge}][,helper=@var{helper}]
Connect a host TAP network interface to a host bridge device.

Use the network helper @var{helper} to configure the TAP interface and
attach it to the bridge. The default network helper executable is
@file{/path/to/qemu-bridge-helper} and the default bridge
device is @file{br0}.

Examples:

@example
#launch a QEMU instance with the default network helper to
#connect a TAP device to bridge br0
@value{qemu_system} linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
@end example

@example
#launch a QEMU instance with the default network helper to
#connect a TAP device to bridge qemubr0
@value{qemu_system} linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
@end example

@item -netdev socket,id=@var{id}[,fd=@var{h}][,listen=[@var{host}]:@var{port}][,connect=@var{host}:@var{port}]

This host network backend can be used to connect the guest's network to
another QEMU virtual machine using a TCP socket connection. If @option{listen}
is specified, QEMU waits for incoming connections on @var{port}
(@var{host} is optional). @option{connect} is used to connect to
another QEMU instance using the @option{listen} option. @option{fd}=@var{h}
specifies an already opened TCP socket.

Example:
@example
# launch a first QEMU instance
@value{qemu_system} linux.img \
                 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                 -netdev socket,id=n1,listen=:1234
# connect the network of this instance to the network of the first instance
@value{qemu_system} linux.img \
                 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
                 -netdev socket,id=n2,connect=127.0.0.1:1234
@end example

@item -netdev socket,id=@var{id}[,fd=@var{h}][,mcast=@var{maddr}:@var{port}[,localaddr=@var{addr}]]

Configure a socket host network backend to share the guest's network traffic
with another QEMU virtual machines using a UDP multicast socket, effectively
making a bus for every QEMU with same multicast address @var{maddr} and @var{port}.
NOTES:
@enumerate
@item
Several QEMU can be running on different hosts and share same bus (assuming
correct multicast setup for these hosts).
@item
mcast support is compatible with User Mode Linux (argument @option{eth@var{N}=mcast}), see
@url{http://user-mode-linux.sf.net}.
@item
Use @option{fd=h} to specify an already opened UDP multicast socket.
@end enumerate

Example:
@example
# launch one QEMU instance
@value{qemu_system} linux.img \
                 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                 -netdev socket,id=n1,mcast=230.0.0.1:1234
# launch another QEMU instance on same "bus"
@value{qemu_system} linux.img \
                 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
                 -netdev socket,id=n2,mcast=230.0.0.1:1234
# launch yet another QEMU instance on same "bus"
@value{qemu_system} linux.img \
                 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \
                 -netdev socket,id=n3,mcast=230.0.0.1:1234
@end example

Example (User Mode Linux compat.):
@example
# launch QEMU instance (note mcast address selected is UML's default)
@value{qemu_system} linux.img \
                 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                 -netdev socket,id=n1,mcast=239.192.168.1:1102
# launch UML
/path/to/linux ubd0=/path/to/root_fs eth0=mcast
@end example

Example (send packets from host's 1.2.3.4):
@example
@value{qemu_system} linux.img \
                 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
@end example

@item -netdev l2tpv3,id=@var{id},src=@var{srcaddr},dst=@var{dstaddr}[,srcport=@var{srcport}][,dstport=@var{dstport}],txsession=@var{txsession}[,rxsession=@var{rxsession}][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=@var{txcookie}][,rxcookie=@var{rxcookie}][,offset=@var{offset}]
Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931) is a
popular protocol to transport Ethernet (and other Layer 2) data frames between
two systems. It is present in routers, firewalls and the Linux kernel
(from version 3.3 onwards).

This transport allows a VM to communicate to another VM, router or firewall directly.

@table @option
@item src=@var{srcaddr}
    source address (mandatory)
@item dst=@var{dstaddr}
    destination address (mandatory)
@item udp
    select udp encapsulation (default is ip).
@item srcport=@var{srcport}
    source udp port.
@item dstport=@var{dstport}
    destination udp port.
@item ipv6
    force v6, otherwise defaults to v4.
@item rxcookie=@var{rxcookie}
@itemx txcookie=@var{txcookie}
    Cookies are a weak form of security in the l2tpv3 specification.
Their function is mostly to prevent misconfiguration. By default they are 32
bit.
@item cookie64
    Set cookie size to 64 bit instead of the default 32
@item counter=off
    Force a 'cut-down' L2TPv3 with no counter as in
draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
@item pincounter=on
    Work around broken counter handling in peer. This may also help on
networks which have packet reorder.
@item offset=@var{offset}
    Add an extra offset between header and data
@end table

For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to the bridge br-lan
on the remote Linux host 1.2.3.4:
@example
# Setup tunnel on linux host using raw ip as encapsulation
# on 1.2.3.4
ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \
    encap udp udp_sport 16384 udp_dport 16384
ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \
    0xFFFFFFFF peer_session_id 0xFFFFFFFF
ifconfig vmtunnel0 mtu 1500
ifconfig vmtunnel0 up
brctl addif br-lan vmtunnel0


# on 4.3.2.1
# launch QEMU instance - if your network has reorder or is very lossy add ,pincounter

@value{qemu_system} linux.img -device e1000,netdev=n1 \
    -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter

@end example

@item -netdev vde,id=@var{id}[,sock=@var{socketpath}][,port=@var{n}][,group=@var{groupname}][,mode=@var{octalmode}]
Configure VDE backend to connect to PORT @var{n} of a vde switch running on host and
listening for incoming connections on @var{socketpath}. Use GROUP @var{groupname}
and MODE @var{octalmode} to change default ownership and permissions for
communication port. This option is only available if QEMU has been compiled
with vde support enabled.

Example:
@example
# launch vde switch
vde_switch -F -sock /tmp/myswitch
# launch QEMU instance
@value{qemu_system} linux.img -nic vde,sock=/tmp/myswitch
@end example

@item -netdev vhost-user,chardev=@var{id}[,vhostforce=on|off][,queues=n]

Establish a vhost-user netdev, backed by a chardev @var{id}. The chardev should
be a unix domain socket backed one. The vhost-user uses a specifically defined
protocol to pass vhost ioctl replacement messages to an application on the other
end of the socket. On non-MSIX guests, the feature can be forced with
@var{vhostforce}. Use 'queues=@var{n}' to specify the number of queues to
be created for multiqueue vhost-user.

Example:
@example
qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
     -numa node,memdev=mem \
     -chardev socket,id=chr0,path=/path/to/socket \
     -netdev type=vhost-user,id=net0,chardev=chr0 \
     -device virtio-net-pci,netdev=net0
@end example

@item -netdev hubport,id=@var{id},hubid=@var{hubid}[,netdev=@var{nd}]

Create a hub port on the emulated hub with ID @var{hubid}.

The hubport netdev lets you connect a NIC to a QEMU emulated hub instead of a
single netdev. Alternatively, you can also connect the hubport to another
netdev with ID @var{nd} by using the @option{netdev=@var{nd}} option.

@item -net nic[,netdev=@var{nd}][,macaddr=@var{mac}][,model=@var{type}] [,name=@var{name}][,addr=@var{addr}][,vectors=@var{v}]
@findex -net
Legacy option to configure or create an on-board (or machine default) Network
Interface Card(NIC) and connect it either to the emulated hub with ID 0 (i.e.
the default hub), or to the netdev @var{nd}.
If @var{model} is omitted, then the default NIC model associated with
the machine type is used. Note that the default NIC model may change in
future QEMU releases, so it is highly recommended to always specify a model.
Optionally, the MAC address can be changed to @var{mac}, the device
address set to @var{addr} (PCI cards only), and a @var{name} can be
assigned for use in monitor commands.
Optionally, for PCI cards, you can specify the number @var{v} of MSI-X vectors
that the card should have; this option currently only affects virtio cards; set
@var{v} = 0 to disable MSI-X. If no @option{-net} option is specified, a single
NIC is created.  QEMU can emulate several different models of network card.
Use @code{-net nic,model=help} for a list of available devices for your target.

@item -net user|tap|bridge|socket|l2tpv3|vde[,...][,name=@var{name}]
Configure a host network backend (with the options corresponding to the same
@option{-netdev} option) and connect it to the emulated hub 0 (the default
hub). Use @var{name} to specify the name of the hub port.
ETEXI
SRST
``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]``
    This option is a shortcut for configuring both the on-board
    (default) guest NIC hardware and the host network backend in one go.
    The host backend options are the same as with the corresponding
    ``-netdev`` options below. The guest NIC model can be set with
    ``model=modelname``. Use ``model=help`` to list the available device
    types. The hardware MAC address can be set with ``mac=macaddr``.

    The following two example do exactly the same, to show how ``-nic``
    can be used to shorten the command line length:

    .. parsed-literal::

        |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
        |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32

``-nic none``
    Indicate that no network devices should be configured. It is used to
    override the default configuration (default NIC with "user" host
    network backend) which is activated if no other networking options
    are provided.

``-netdev user,id=id[,option][,option][,...]``
    Configure user mode host network backend which requires no
    administrator privilege to run. Valid options are:

    ``id=id``
        Assign symbolic name for use in monitor commands.

    ``ipv4=on|off and ipv6=on|off``
        Specify that either IPv4 or IPv6 must be enabled. If neither is
        specified both protocols are enabled.

    ``net=addr[/mask]``
        Set IP network address the guest will see. Optionally specify
        the netmask, either in the form a.b.c.d or as number of valid
        top-most bits. Default is 10.0.2.0/24.

    ``host=addr``
        Specify the guest-visible address of the host. Default is the
        2nd IP in the guest network, i.e. x.x.x.2.

    ``ipv6-net=addr[/int]``
        Set IPv6 network address the guest will see (default is
        fec0::/64). The network prefix is given in the usual hexadecimal
        IPv6 address notation. The prefix size is optional, and is given
        as the number of valid top-most bits (default is 64).

    ``ipv6-host=addr``
        Specify the guest-visible IPv6 address of the host. Default is
        the 2nd IPv6 in the guest network, i.e. xxxx::2.

    ``restrict=on|off``
        If this option is enabled, the guest will be isolated, i.e. it
        will not be able to contact the host and no guest IP packets
        will be routed over the host to the outside. This option does
        not affect any explicitly set forwarding rules.

    ``hostname=name``
        Specifies the client hostname reported by the built-in DHCP
        server.

    ``dhcpstart=addr``
        Specify the first of the 16 IPs the built-in DHCP server can
        assign. Default is the 15th to 31st IP in the guest network,
        i.e. x.x.x.15 to x.x.x.31.

    ``dns=addr``
        Specify the guest-visible address of the virtual nameserver. The
        address must be different from the host address. Default is the
        3rd IP in the guest network, i.e. x.x.x.3.

    ``ipv6-dns=addr``
        Specify the guest-visible address of the IPv6 virtual
        nameserver. The address must be different from the host address.
        Default is the 3rd IP in the guest network, i.e. xxxx::3.

    ``dnssearch=domain``
        Provides an entry for the domain-search list sent by the
        built-in DHCP server. More than one domain suffix can be
        transmitted by specifying this option multiple times. If
        supported, this will cause the guest to automatically try to
        append the given domain suffix(es) in case a domain name can not
        be resolved.

        Example:

        .. parsed-literal::

            |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org

    ``domainname=domain``
        Specifies the client domain name reported by the built-in DHCP
        server.

    ``tftp=dir``
        When using the user mode network stack, activate a built-in TFTP
        server. The files in dir will be exposed as the root of a TFTP
        server. The TFTP client on the guest must be configured in
        binary mode (use the command ``bin`` of the Unix TFTP client).

    ``tftp-server-name=name``
        In BOOTP reply, broadcast name as the "TFTP server name"
        (RFC2132 option 66). This can be used to advise the guest to
        load boot files or configurations from a different server than
        the host address.

    ``bootfile=file``
        When using the user mode network stack, broadcast file as the
        BOOTP filename. In conjunction with ``tftp``, this can be used
        to network boot a guest from a local directory.

        Example (using pxelinux):

        .. parsed-literal::

            |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \
                -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0

    ``smb=dir[,smbserver=addr]``
        When using the user mode network stack, activate a built-in SMB
        server so that Windows OSes can access to the host files in
        ``dir`` transparently. The IP address of the SMB server can be
        set to addr. By default the 4th IP in the guest network is used,
        i.e. x.x.x.4.

        In the guest Windows OS, the line:

        ::

            10.0.2.4 smbserver

        must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows
        9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows
        NT/2000).

        Then ``dir`` can be accessed in ``\\smbserver\qemu``.

        Note that a SAMBA server must be installed on the host OS.

    ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
        Redirect incoming TCP or UDP connections to the host port
        hostport to the guest IP address guestaddr on guest port
        guestport. If guestaddr is not specified, its value is x.x.x.15
        (default first address given by the built-in DHCP server). By
        specifying hostaddr, the rule can be bound to a specific host
        interface. If no connection type is set, TCP is used. This
        option can be given multiple times.

        For example, to redirect host X11 connection from screen 1 to
        guest screen 0, use the following:

        ::

            # on the host
            |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
            # this host xterm should open in the guest X11 server
            xterm -display :1

        To redirect telnet connections from host port 5555 to telnet
        port on the guest, use the following:

        ::

            # on the host
            |qemu_system| -nic user,hostfwd=tcp::5555-:23
            telnet localhost 5555

        Then when you use on the host ``telnet localhost 5555``, you
        connect to the guest telnet server.

    ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command``
        Forward guest TCP connections to the IP address server on port
        port to the character device dev or to a program executed by
        cmd:command which gets spawned for each connection. This option
        can be given multiple times.

        You can either use a chardev directly and have that one used
        throughout QEMU's lifetime, like in the following example:

        ::

            # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
            # the guest accesses it
            |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321

        Or you can execute a command on every TCP connection established
        by the guest, so that QEMU behaves similar to an inetd process
        for that virtual server:

        ::

            # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
            # and connect the TCP stream to its stdin/stdout
            |qemu_system| -nic  'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'

``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
    Configure a host TAP network backend with ID id.

    Use the network script file to configure it and the network script
    dfile to deconfigure it. If name is not provided, the OS
    automatically provides one. The default network configure script is
    ``/etc/qemu-ifup`` and the default network deconfigure script is
    ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
    disable script execution.

    If running QEMU as an unprivileged user, use the network helper
    helper to configure the TAP interface and attach it to the bridge.
    The default network helper executable is
    ``/path/to/qemu-bridge-helper`` and the default bridge device is
    ``br0``.

    ``fd``\ =h can be used to specify the handle of an already opened
    host TAP interface.

    Examples:

    ::

        #launch a QEMU instance with the default network script
        |qemu_system| linux.img -nic tap

    ::

        #launch a QEMU instance with two NICs, each one connected
        #to a TAP device
        |qemu_system| linux.img \
                -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \
                -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1

    ::

        #launch a QEMU instance with the default network helper to
        #connect a TAP device to bridge br0
        |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \
                -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"

``-netdev bridge,id=id[,br=bridge][,helper=helper]``
    Connect a host TAP network interface to a host bridge device.

    Use the network helper helper to configure the TAP interface and
    attach it to the bridge. The default network helper executable is
    ``/path/to/qemu-bridge-helper`` and the default bridge device is
    ``br0``.

    Examples:

    ::

        #launch a QEMU instance with the default network helper to
        #connect a TAP device to bridge br0
        |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1

    ::

        #launch a QEMU instance with the default network helper to
        #connect a TAP device to bridge qemubr0
        |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1

``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
    This host network backend can be used to connect the guest's network
    to another QEMU virtual machine using a TCP socket connection. If
    ``listen`` is specified, QEMU waits for incoming connections on port
    (host is optional). ``connect`` is used to connect to another QEMU
    instance using the ``listen`` option. ``fd``\ =h specifies an
    already opened TCP socket.

    Example:

    ::

        # launch a first QEMU instance
        |qemu_system| linux.img \
                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                         -netdev socket,id=n1,listen=:1234
        # connect the network of this instance to the network of the first instance
        |qemu_system| linux.img \
                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
                         -netdev socket,id=n2,connect=127.0.0.1:1234

``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]``
    Configure a socket host network backend to share the guest's network
    traffic with another QEMU virtual machines using a UDP multicast
    socket, effectively making a bus for every QEMU with same multicast
    address maddr and port. NOTES:

    1. Several QEMU can be running on different hosts and share same bus
       (assuming correct multicast setup for these hosts).

    2. mcast support is compatible with User Mode Linux (argument
       ``ethN=mcast``), see http://user-mode-linux.sf.net.

    3. Use ``fd=h`` to specify an already opened UDP multicast socket.

    Example:

    ::

        # launch one QEMU instance
        |qemu_system| linux.img \
                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                         -netdev socket,id=n1,mcast=230.0.0.1:1234
        # launch another QEMU instance on same "bus"
        |qemu_system| linux.img \
                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
                         -netdev socket,id=n2,mcast=230.0.0.1:1234
        # launch yet another QEMU instance on same "bus"
        |qemu_system| linux.img \
                         -device e1000,netdev=n3,mac=52:54:00:12:34:58 \
                         -netdev socket,id=n3,mcast=230.0.0.1:1234

    Example (User Mode Linux compat.):

    ::

        # launch QEMU instance (note mcast address selected is UML's default)
        |qemu_system| linux.img \
                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                         -netdev socket,id=n1,mcast=239.192.168.1:1102
        # launch UML
        /path/to/linux ubd0=/path/to/root_fs eth0=mcast

    Example (send packets from host's 1.2.3.4):

    .. parsed-literal::

        |qemu_system| linux.img \
                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
                         -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4

``-netdev l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]``
    Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
    is a popular protocol to transport Ethernet (and other Layer 2) data
    frames between two systems. It is present in routers, firewalls and
    the Linux kernel (from version 3.3 onwards).

    This transport allows a VM to communicate to another VM, router or
    firewall directly.

    ``src=srcaddr``
        source address (mandatory)

    ``dst=dstaddr``
        destination address (mandatory)

    ``udp``
        select udp encapsulation (default is ip).

    ``srcport=srcport``
        source udp port.

    ``dstport=dstport``
        destination udp port.

    ``ipv6``
        force v6, otherwise defaults to v4.

    ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
        Cookies are a weak form of security in the l2tpv3 specification.
        Their function is mostly to prevent misconfiguration. By default
        they are 32 bit.

    ``cookie64``
        Set cookie size to 64 bit instead of the default 32

    ``counter=off``
        Force a 'cut-down' L2TPv3 with no counter as in
        draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00

    ``pincounter=on``
        Work around broken counter handling in peer. This may also help
        on networks which have packet reorder.

    ``offset=offset``
        Add an extra offset between header and data

    For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to
    the bridge br-lan on the remote Linux host 1.2.3.4:

    ::

        # Setup tunnel on linux host using raw ip as encapsulation
        # on 1.2.3.4
        ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \
            encap udp udp_sport 16384 udp_dport 16384
        ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \
            0xFFFFFFFF peer_session_id 0xFFFFFFFF
        ifconfig vmtunnel0 mtu 1500
        ifconfig vmtunnel0 up
        brctl addif br-lan vmtunnel0


        # on 4.3.2.1
        # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter

        |qemu_system| linux.img -device e1000,netdev=n1 \
            -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter

``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
    Configure VDE backend to connect to PORT n of a vde switch running
    on host and listening for incoming connections on socketpath. Use
    GROUP groupname and MODE octalmode to change default ownership and
    permissions for communication port. This option is only available if
    QEMU has been compiled with vde support enabled.

    Example:

    ::

        # launch vde switch
        vde_switch -F -sock /tmp/myswitch
        # launch QEMU instance
        |qemu_system| linux.img -nic vde,sock=/tmp/myswitch

``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
    Establish a vhost-user netdev, backed by a chardev id. The chardev
    should be a unix domain socket backed one. The vhost-user uses a
    specifically defined protocol to pass vhost ioctl replacement
    messages to an application on the other end of the socket. On
    non-MSIX guests, the feature can be forced with vhostforce. Use
    'queues=n' to specify the number of queues to be created for
    multiqueue vhost-user.

    Example:

    ::

        qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
             -numa node,memdev=mem \
             -chardev socket,id=chr0,path=/path/to/socket \
             -netdev type=vhost-user,id=net0,chardev=chr0 \
             -device virtio-net-pci,netdev=net0

``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
    Create a hub port on the emulated hub with ID hubid.

    The hubport netdev lets you connect a NIC to a QEMU emulated hub
    instead of a single netdev. Alternatively, you can also connect the
    hubport to another netdev with ID nd by using the ``netdev=nd``
    option.

``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
    Legacy option to configure or create an on-board (or machine
    default) Network Interface Card(NIC) and connect it either to the
    emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
    If model is omitted, then the default NIC model associated with the
    machine type is used. Note that the default NIC model may change in
    future QEMU releases, so it is highly recommended to always specify
    a model. Optionally, the MAC address can be changed to mac, the
    device address set to addr (PCI cards only), and a name can be
    assigned for use in monitor commands. Optionally, for PCI cards, you
    can specify the number v of MSI-X vectors that the card should have;
    this option currently only affects virtio cards; set v = 0 to
    disable MSI-X. If no ``-net`` option is specified, a single NIC is
    created. QEMU can emulate several different models of network card.
    Use ``-net nic,model=help`` for a list of available devices for your
    target.

``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
    Configure a host network backend (with the options corresponding to
    the same ``-netdev`` option) and connect it to the emulated hub 0
    (the default hub). Use name to specify the name of the hub port.
ERST

STEXI
@end table
ETEXI
DEFHEADING()

DEFHEADING(Character device options:)

DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
    "-chardev help\n"
    "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n"
    "         [,server][,nowait][,telnet][,websocket][,reconnect=seconds][,mux=on|off]\n"
    "         [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
    "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,websocket][,reconnect=seconds]\n"
    "         [,mux=on|off][,logfile=PATH][,logappend=on|off] (unix)\n"
    "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
    "         [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n"
    "         [,logfile=PATH][,logappend=on|off]\n"
    "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
    "         [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
    "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
#ifdef _WIN32
    "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
#else
    "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
#endif
#ifdef CONFIG_BRLAPI
    "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
#endif
#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
        || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
#endif
#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
    "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
    "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
#endif
#if defined(CONFIG_SPICE)
    "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
    "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
#endif
    , QEMU_ARCH_ALL
)

STEXI

The general form of a character device option is:
@table @option
@item -chardev @var{backend},id=@var{id}[,mux=on|off][,@var{options}]
@findex -chardev
Backend is one of:
@option{null},
@option{socket},
@option{udp},
@option{msmouse},
@option{vc},
@option{ringbuf},
@option{file},
@option{pipe},
@option{console},
@option{serial},
@option{pty},
@option{stdio},
@option{braille},
@option{tty},
@option{parallel},
@option{parport},
@option{spicevmc},
@option{spiceport}.
The specific backend will determine the applicable options.

Use @code{-chardev help} to print all available chardev backend types.

All devices must have an id, which can be any string up to 127 characters long.
It is used to uniquely identify this device in other command line directives.

A character device may be used in multiplexing mode by multiple front-ends.
Specify @option{mux=on} to enable this mode.
A multiplexer is a "1:N" device, and here the "1" end is your specified chardev
backend, and the "N" end is the various parts of QEMU that can talk to a chardev.
If you create a chardev with @option{id=myid} and @option{mux=on}, QEMU will
create a multiplexer with your specified ID, and you can then configure multiple
front ends to use that chardev ID for their input/output. Up to four different
front ends can be connected to a single multiplexed chardev. (Without
multiplexing enabled, a chardev can only be used by a single front end.)
For instance you could use this to allow a single stdio chardev to be used by
two serial ports and the QEMU monitor:

@example
-chardev stdio,mux=on,id=char0 \
-mon chardev=char0,mode=readline \
-serial chardev:char0 \
-serial chardev:char0
@end example

You can have more than one multiplexer in a system configuration; for instance
you could have a TCP port multiplexed between UART 0 and UART 1, and stdio
multiplexed between the QEMU monitor and a parallel port:

@example
-chardev stdio,mux=on,id=char0 \
-mon chardev=char0,mode=readline \
-parallel chardev:char0 \
-chardev tcp,...,mux=on,id=char1 \
-serial chardev:char1 \
-serial chardev:char1
@end example

When you're using a multiplexed character device, some escape sequences are
interpreted in the input. @xref{mux_keys, Keys in the character backend
multiplexer}.

Note that some other command line options may implicitly create multiplexed
character backends; for instance @option{-serial mon:stdio} creates a
multiplexed stdio backend connected to the serial port and the QEMU monitor,
and @option{-nographic} also multiplexes the console and the monitor to
stdio.

There is currently no support for multiplexing in the other direction
(where a single QEMU front end takes input and output from multiple chardevs).

Every backend supports the @option{logfile} option, which supplies the path
to a file to record all data transmitted via the backend. The @option{logappend}
option controls whether the log file will be truncated or appended to when
opened.

@end table

The available backends are:

@table @option
@item -chardev null,id=@var{id}
A void device. This device will not emit any data, and will drop any data it
receives. The null backend does not take any options.

@item -chardev socket,id=@var{id}[,@var{TCP options} or @var{unix options}][,server][,nowait][,telnet][,websocket][,reconnect=@var{seconds}][,tls-creds=@var{id}][,tls-authz=@var{id}]

Create a two-way stream socket, which can be either a TCP or a unix socket. A
unix socket will be created if @option{path} is specified. Behaviour is
undefined if TCP options are specified for a unix socket.

@option{server} specifies that the socket shall be a listening socket.

@option{nowait} specifies that QEMU should not block waiting for a client to
connect to a listening socket.

@option{telnet} specifies that traffic on the socket should interpret telnet
escape sequences.

@option{websocket} specifies that the socket uses WebSocket protocol for
communication.

@option{reconnect} sets the timeout for reconnecting on non-server sockets when
the remote end goes away.  qemu will delay this many seconds and then attempt
to reconnect.  Zero disables reconnecting, and is the default.

@option{tls-creds} requests enablement of the TLS protocol for encryption,
and specifies the id of the TLS credentials to use for the handshake. The
credentials must be previously created with the @option{-object tls-creds}
argument.

@option{tls-auth} provides the ID of the QAuthZ authorization object against
which the client's x509 distinguished name will be validated. This object is
only resolved at time of use, so can be deleted and recreated on the fly
while the chardev server is active. If missing, it will default to denying
access.

TCP and unix socket options are given below:

@table @option

@item TCP options: port=@var{port}[,host=@var{host}][,to=@var{to}][,ipv4][,ipv6][,nodelay]

@option{host} for a listening socket specifies the local address to be bound.
For a connecting socket species the remote host to connect to. @option{host} is
optional for listening sockets. If not specified it defaults to @code{0.0.0.0}.

@option{port} for a listening socket specifies the local port to be bound. For a
connecting socket specifies the port on the remote host to connect to.
@option{port} can be given as either a port number or a service name.
@option{port} is required.

@option{to} is only relevant to listening sockets. If it is specified, and
@option{port} cannot be bound, QEMU will attempt to bind to subsequent ports up
to and including @option{to} until it succeeds. @option{to} must be specified
as a port number.

@option{ipv4} and @option{ipv6} specify that either IPv4 or IPv6 must be used.
If neither is specified the socket may use either protocol.

@option{nodelay} disables the Nagle algorithm.

@item unix options: path=@var{path}

@option{path} specifies the local path of the unix socket. @option{path} is
required.

@end table

@item -chardev udp,id=@var{id}[,host=@var{host}],port=@var{port}[,localaddr=@var{localaddr}][,localport=@var{localport}][,ipv4][,ipv6]

Sends all traffic from the guest to a remote host over UDP.

@option{host} specifies the remote host to connect to. If not specified it
defaults to @code{localhost}.

@option{port} specifies the port on the remote host to connect to. @option{port}
is required.

@option{localaddr} specifies the local address to bind to. If not specified it
defaults to @code{0.0.0.0}.

@option{localport} specifies the local port to bind to. If not specified any
available local port will be used.

@option{ipv4} and @option{ipv6} specify that either IPv4 or IPv6 must be used.
If neither is specified the device may use either protocol.

@item -chardev msmouse,id=@var{id}

Forward QEMU's emulated msmouse events to the guest. @option{msmouse} does not
take any options.

@item -chardev vc,id=@var{id}[[,width=@var{width}][,height=@var{height}]][[,cols=@var{cols}][,rows=@var{rows}]]

Connect to a QEMU text console. @option{vc} may optionally be given a specific
size.

@option{width} and @option{height} specify the width and height respectively of
the console, in pixels.

@option{cols} and @option{rows} specify that the console be sized to fit a text
console with the given dimensions.

@item -chardev ringbuf,id=@var{id}[,size=@var{size}]

Create a ring buffer with fixed size @option{size}.
@var{size} must be a power of two and defaults to @code{64K}.

@item -chardev file,id=@var{id},path=@var{path}

Log all traffic received from the guest to a file.

@option{path} specifies the path of the file to be opened. This file will be
created if it does not already exist, and overwritten if it does. @option{path}
is required.

@item -chardev pipe,id=@var{id},path=@var{path}

Create a two-way connection to the guest. The behaviour differs slightly between
Windows hosts and other hosts:

On Windows, a single duplex pipe will be created at
@file{\\.pipe\@option{path}}.

On other hosts, 2 pipes will be created called @file{@option{path}.in} and
@file{@option{path}.out}. Data written to @file{@option{path}.in} will be
received by the guest. Data written by the guest can be read from
@file{@option{path}.out}. QEMU will not create these fifos, and requires them to
be present.

@option{path} forms part of the pipe path as described above. @option{path} is
required.

@item -chardev console,id=@var{id}

Send traffic from the guest to QEMU's standard output. @option{console} does not
take any options.

@option{console} is only available on Windows hosts.

@item -chardev serial,id=@var{id},path=@option{path}

Send traffic from the guest to a serial device on the host.

On Unix hosts serial will actually accept any tty device,
not only serial lines.

@option{path} specifies the name of the serial device to open.

@item -chardev pty,id=@var{id}

Create a new pseudo-terminal on the host and connect to it. @option{pty} does
not take any options.

@option{pty} is not available on Windows hosts.

@item -chardev stdio,id=@var{id}[,signal=on|off]
Connect to standard input and standard output of the QEMU process.

@option{signal} controls if signals are enabled on the terminal, that includes
exiting QEMU with the key sequence @key{Control-c}. This option is enabled by
default, use @option{signal=off} to disable it.

@item -chardev braille,id=@var{id}

Connect to a local BrlAPI server. @option{braille} does not take any options.

@item -chardev tty,id=@var{id},path=@var{path}

@option{tty} is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD and
DragonFlyBSD hosts.  It is an alias for @option{serial}.

@option{path} specifies the path to the tty. @option{path} is required.

@item -chardev parallel,id=@var{id},path=@var{path}
@itemx -chardev parport,id=@var{id},path=@var{path}

@option{parallel} is only available on Linux, FreeBSD and DragonFlyBSD hosts.

Connect to a local parallel port.

@option{path} specifies the path to the parallel port device. @option{path} is
required.

@item -chardev spicevmc,id=@var{id},debug=@var{debug},name=@var{name}

@option{spicevmc} is only available when spice support is built in.

@option{debug} debug level for spicevmc

@option{name} name of spice channel to connect to

Connect to a spice virtual machine channel, such as vdiport.

@item -chardev spiceport,id=@var{id},debug=@var{debug},name=@var{name}

@option{spiceport} is only available when spice support is built in.

@option{debug} debug level for spicevmc

@option{name} name of spice port to connect to

Connect to a spice port, allowing a Spice client to handle the traffic
identified by a name (preferably a fqdn).
ETEXI
SRST
The general form of a character device option is:

``-chardev backend,id=id[,mux=on|off][,options]``
    Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
    ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
    ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``,
    ``spicevmc``, ``spiceport``. The specific backend will determine the
    applicable options.

    Use ``-chardev help`` to print all available chardev backend types.

    All devices must have an id, which can be any string up to 127
    characters long. It is used to uniquely identify this device in
    other command line directives.

    A character device may be used in multiplexing mode by multiple
    front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
    a "1:N" device, and here the "1" end is your specified chardev
    backend, and the "N" end is the various parts of QEMU that can talk
    to a chardev. If you create a chardev with ``id=myid`` and
    ``mux=on``, QEMU will create a multiplexer with your specified ID,
    and you can then configure multiple front ends to use that chardev
    ID for their input/output. Up to four different front ends can be
    connected to a single multiplexed chardev. (Without multiplexing
    enabled, a chardev can only be used by a single front end.) For
    instance you could use this to allow a single stdio chardev to be
    used by two serial ports and the QEMU monitor:

    ::

        -chardev stdio,mux=on,id=char0 \
        -mon chardev=char0,mode=readline \
        -serial chardev:char0 \
        -serial chardev:char0

    You can have more than one multiplexer in a system configuration;
    for instance you could have a TCP port multiplexed between UART 0
    and UART 1, and stdio multiplexed between the QEMU monitor and a
    parallel port:

    ::

        -chardev stdio,mux=on,id=char0 \
        -mon chardev=char0,mode=readline \
        -parallel chardev:char0 \
        -chardev tcp,...,mux=on,id=char1 \
        -serial chardev:char1 \
        -serial chardev:char1

    When you're using a multiplexed character device, some escape
    sequences are interpreted in the input. See :ref:`mux_005fkeys`.

    Note that some other command line options may implicitly create
    multiplexed character backends; for instance ``-serial mon:stdio``
    creates a multiplexed stdio backend connected to the serial port and
    the QEMU monitor, and ``-nographic`` also multiplexes the console
    and the monitor to stdio.

    There is currently no support for multiplexing in the other
    direction (where a single QEMU front end takes input and output from
    multiple chardevs).

    Every backend supports the ``logfile`` option, which supplies the
    path to a file to record all data transmitted via the backend. The
    ``logappend`` option controls whether the log file will be truncated
    or appended to when opened.

The available backends are:

``-chardev null,id=id``
    A void device. This device will not emit any data, and will drop any
    data it receives. The null backend does not take any options.

``-chardev socket,id=id[,TCP options or unix options][,server][,nowait][,telnet][,websocket][,reconnect=seconds][,tls-creds=id][,tls-authz=id]``
    Create a two-way stream socket, which can be either a TCP or a unix
    socket. A unix socket will be created if ``path`` is specified.
    Behaviour is undefined if TCP options are specified for a unix
    socket.

    ``server`` specifies that the socket shall be a listening socket.

    ``nowait`` specifies that QEMU should not block waiting for a client
    to connect to a listening socket.

    ``telnet`` specifies that traffic on the socket should interpret
    telnet escape sequences.

    ``websocket`` specifies that the socket uses WebSocket protocol for
    communication.

    ``reconnect`` sets the timeout for reconnecting on non-server
    sockets when the remote end goes away. qemu will delay this many
    seconds and then attempt to reconnect. Zero disables reconnecting,
    and is the default.

    ``tls-creds`` requests enablement of the TLS protocol for
    encryption, and specifies the id of the TLS credentials to use for
    the handshake. The credentials must be previously created with the
    ``-object tls-creds`` argument.

    ``tls-auth`` provides the ID of the QAuthZ authorization object
    against which the client's x509 distinguished name will be
    validated. This object is only resolved at time of use, so can be
    deleted and recreated on the fly while the chardev server is active.
    If missing, it will default to denying access.

    TCP and unix socket options are given below:

    ``TCP options: port=port[,host=host][,to=to][,ipv4][,ipv6][,nodelay]``
        ``host`` for a listening socket specifies the local address to
        be bound. For a connecting socket species the remote host to
        connect to. ``host`` is optional for listening sockets. If not
        specified it defaults to ``0.0.0.0``.

        ``port`` for a listening socket specifies the local port to be
        bound. For a connecting socket specifies the port on the remote
        host to connect to. ``port`` can be given as either a port
        number or a service name. ``port`` is required.

        ``to`` is only relevant to listening sockets. If it is
        specified, and ``port`` cannot be bound, QEMU will attempt to
        bind to subsequent ports up to and including ``to`` until it
        succeeds. ``to`` must be specified as a port number.

        ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be
        used. If neither is specified the socket may use either
        protocol.

        ``nodelay`` disables the Nagle algorithm.

    ``unix options: path=path``
        ``path`` specifies the local path of the unix socket. ``path``
        is required.

``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4][,ipv6]``
    Sends all traffic from the guest to a remote host over UDP.

    ``host`` specifies the remote host to connect to. If not specified
    it defaults to ``localhost``.

    ``port`` specifies the port on the remote host to connect to.
    ``port`` is required.

    ``localaddr`` specifies the local address to bind to. If not
    specified it defaults to ``0.0.0.0``.

    ``localport`` specifies the local port to bind to. If not specified
    any available local port will be used.

    ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be used.
    If neither is specified the device may use either protocol.

``-chardev msmouse,id=id``
    Forward QEMU's emulated msmouse events to the guest. ``msmouse``
    does not take any options.

``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
    Connect to a QEMU text console. ``vc`` may optionally be given a
    specific size.

    ``width`` and ``height`` specify the width and height respectively
    of the console, in pixels.

    ``cols`` and ``rows`` specify that the console be sized to fit a
    text console with the given dimensions.

``-chardev ringbuf,id=id[,size=size]``
    Create a ring buffer with fixed size ``size``. size must be a power
    of two and defaults to ``64K``.

``-chardev file,id=id,path=path``
    Log all traffic received from the guest to a file.

    ``path`` specifies the path of the file to be opened. This file will
    be created if it does not already exist, and overwritten if it does.
    ``path`` is required.

``-chardev pipe,id=id,path=path``
    Create a two-way connection to the guest. The behaviour differs
    slightly between Windows hosts and other hosts:

    On Windows, a single duplex pipe will be created at
    ``\\.pipe\path``.

    On other hosts, 2 pipes will be created called ``path.in`` and
    ``path.out``. Data written to ``path.in`` will be received by the
    guest. Data written by the guest can be read from ``path.out``. QEMU
    will not create these fifos, and requires them to be present.

    ``path`` forms part of the pipe path as described above. ``path`` is
    required.

``-chardev console,id=id``
    Send traffic from the guest to QEMU's standard output. ``console``
    does not take any options.

    ``console`` is only available on Windows hosts.

``-chardev serial,id=id,path=path``
    Send traffic from the guest to a serial device on the host.

    On Unix hosts serial will actually accept any tty device, not only
    serial lines.

    ``path`` specifies the name of the serial device to open.

``-chardev pty,id=id``
    Create a new pseudo-terminal on the host and connect to it. ``pty``
    does not take any options.

    ``pty`` is not available on Windows hosts.

``-chardev stdio,id=id[,signal=on|off]``
    Connect to standard input and standard output of the QEMU process.

    ``signal`` controls if signals are enabled on the terminal, that
    includes exiting QEMU with the key sequence Control-c. This option
    is enabled by default, use ``signal=off`` to disable it.

``-chardev braille,id=id``
    Connect to a local BrlAPI server. ``braille`` does not take any
    options.

``-chardev tty,id=id,path=path``
    ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD
    and DragonFlyBSD hosts. It is an alias for ``serial``.

    ``path`` specifies the path to the tty. ``path`` is required.

``-chardev parallel,id=id,path=path``; \ ``-chardev parport,id=id,path=path``
    ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
    hosts.

    Connect to a local parallel port.

    ``path`` specifies the path to the parallel port device. ``path`` is
    required.

``-chardev spicevmc,id=id,debug=debug,name=name``
    ``spicevmc`` is only available when spice support is built in.

    ``debug`` debug level for spicevmc

    ``name`` name of spice channel to connect to

    Connect to a spice virtual machine channel, such as vdiport.

``-chardev spiceport,id=id,debug=debug,name=name``
    ``spiceport`` is only available when spice support is built in.

    ``debug`` debug level for spicevmc

    ``name`` name of spice port to connect to

    Connect to a spice port, allowing a Spice client to handle the
    traffic identified by a name (preferably a fqdn).
ERST

STEXI
@end table
ETEXI
DEFHEADING()

#ifdef CONFIG_TPM
DEFHEADING(TPM device options:)

DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
    "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
    "                use path to provide path to a character device; default is /dev/tpm0\n"
    "                use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
    "                not provided it will be searched for in /sys/class/misc/tpm?/device\n"
    "-tpmdev emulator,id=id,chardev=dev\n"
    "                configure the TPM device using chardev backend\n",
    QEMU_ARCH_ALL)
STEXI

The general form of a TPM device option is:
@table @option

@item -tpmdev @var{backend},id=@var{id}[,@var{options}]
@findex -tpmdev

The specific backend type will determine the applicable options.
The @code{-tpmdev} option creates the TPM backend and requires a
@code{-device} option that specifies the TPM frontend interface model.

Use @code{-tpmdev help} to print all available TPM backend types.

@end table

The available backends are:

@table @option

@item -tpmdev passthrough,id=@var{id},path=@var{path},cancel-path=@var{cancel-path}

(Linux-host only) Enable access to the host's TPM using the passthrough
driver.

@option{path} specifies the path to the host's TPM device, i.e., on
a Linux host this would be @code{/dev/tpm0}.
@option{path} is optional and by default @code{/dev/tpm0} is used.

@option{cancel-path} specifies the path to the host TPM device's sysfs
entry allowing for cancellation of an ongoing TPM command.
@option{cancel-path} is optional and by default QEMU will search for the
sysfs entry to use.

Some notes about using the host's TPM with the passthrough driver:

The TPM device accessed by the passthrough driver must not be
used by any other application on the host.

Since the host's firmware (BIOS/UEFI) has already initialized the TPM,
the VM's firmware (BIOS/UEFI) will not be able to initialize the
TPM again and may therefore not show a TPM-specific menu that would
otherwise allow the user to configure the TPM, e.g., allow the user to
enable/disable or activate/deactivate the TPM.
Further, if TPM ownership is released from within a VM then the host's TPM
will get disabled and deactivated. To enable and activate the
TPM again afterwards, the host has to be rebooted and the user is
required to enter the firmware's menu to enable and activate the TPM.
If the TPM is left disabled and/or deactivated most TPM commands will fail.

To create a passthrough TPM use the following two options:
@example
-tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
@end example
Note that the @code{-tpmdev} id is @code{tpm0} and is referenced by
@code{tpmdev=tpm0} in the device option.

@item -tpmdev emulator,id=@var{id},chardev=@var{dev}

(Linux-host only) Enable access to a TPM emulator using Unix domain socket based
chardev backend.

@option{chardev} specifies the unique ID of a character device backend that provides connection to the software TPM server.

To create a TPM emulator backend device with chardev socket backend:
@example

-chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0

@end example

ETEXI
SRST
The general form of a TPM device option is:

``-tpmdev backend,id=id[,options]``
    The specific backend type will determine the applicable options. The
    ``-tpmdev`` option creates the TPM backend and requires a
    ``-device`` option that specifies the TPM frontend interface model.

    Use ``-tpmdev help`` to print all available TPM backend types.

The available backends are:

``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
    (Linux-host only) Enable access to the host's TPM using the
    passthrough driver.

    ``path`` specifies the path to the host's TPM device, i.e., on a
    Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
    default ``/dev/tpm0`` is used.

    ``cancel-path`` specifies the path to the host TPM device's sysfs
    entry allowing for cancellation of an ongoing TPM command.
    ``cancel-path`` is optional and by default QEMU will search for the
    sysfs entry to use.

    Some notes about using the host's TPM with the passthrough driver:

    The TPM device accessed by the passthrough driver must not be used
    by any other application on the host.

    Since the host's firmware (BIOS/UEFI) has already initialized the
    TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
    the TPM again and may therefore not show a TPM-specific menu that
    would otherwise allow the user to configure the TPM, e.g., allow the
    user to enable/disable or activate/deactivate the TPM. Further, if
    TPM ownership is released from within a VM then the host's TPM will
    get disabled and deactivated. To enable and activate the TPM again
    afterwards, the host has to be rebooted and the user is required to
    enter the firmware's menu to enable and activate the TPM. If the TPM
    is left disabled and/or deactivated most TPM commands will fail.

    To create a passthrough TPM use the following two options:

    ::

        -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0

    Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
    ``tpmdev=tpm0`` in the device option.

``-tpmdev emulator,id=id,chardev=dev``
    (Linux-host only) Enable access to a TPM emulator using Unix domain
    socket based chardev backend.

    ``chardev`` specifies the unique ID of a character device backend
    that provides connection to the software TPM server.

    To create a TPM emulator backend device with chardev socket backend:

    ::

        -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
ERST

STEXI
@end table
ETEXI
DEFHEADING()

#endif

DEFHEADING(Linux/Multiboot boot specific:)
STEXI

When using these options, you can use a given Linux or Multiboot
kernel without installing it in the disk image. It can be useful
for easier testing of various kernels.

@table @option
ETEXI
SRST
When using these options, you can use a given Linux or Multiboot kernel
without installing it in the disk image. It can be useful for easier
testing of various kernels.


ERST

DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
    "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
STEXI
@item -kernel @var{bzImage}
@findex -kernel
Use @var{bzImage} as kernel image. The kernel can be either a Linux kernel
or in multiboot format.
ETEXI
SRST
``-kernel bzImage``
    Use bzImage as kernel image. The kernel can be either a Linux kernel
    or in multiboot format.
ERST

DEF("append", HAS_ARG, QEMU_OPTION_append, \
    "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
STEXI
@item -append @var{cmdline}
@findex -append
Use @var{cmdline} as kernel command line
ETEXI
SRST
``-append cmdline``
    Use cmdline as kernel command line
ERST

DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
           "-initrd file    use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
STEXI
@item -initrd @var{file}
@findex -initrd
Use @var{file} as initial ram disk.

@item -initrd "@var{file1} arg=foo,@var{file2}"

This syntax is only available with multiboot.

Use @var{file1} and @var{file2} as modules and pass arg=foo as parameter to the
first module.
ETEXI
SRST
``-initrd file``
    Use file as initial ram disk.

``-initrd "file1 arg=foo,file2"``
    This syntax is only available with multiboot.

    Use file1 and file2 as modules and pass arg=foo as parameter to the
    first module.
ERST

DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
    "-dtb    file    use 'file' as device tree image\n", QEMU_ARCH_ALL)
STEXI
@item -dtb @var{file}
@findex -dtb
Use @var{file} as a device tree binary (dtb) image and pass it to the kernel
on boot.
ETEXI
SRST
``-dtb file``
    Use file as a device tree binary (dtb) image and pass it to the
    kernel on boot.
ERST

STEXI
@end table
ETEXI
DEFHEADING()

DEFHEADING(Debug/Expert options:)
STEXI
@table @option
ETEXI

DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
    "-fw_cfg [name=]<name>,file=<file>\n"
    "                add named fw_cfg entry with contents from file\n"
    "-fw_cfg [name=]<name>,string=<str>\n"
    "                add named fw_cfg entry with contents from string\n",
    QEMU_ARCH_ALL)
STEXI

@item -fw_cfg [name=]@var{name},file=@var{file}
@findex -fw_cfg
Add named fw_cfg entry with contents from file @var{file}.

@item -fw_cfg [name=]@var{name},string=@var{str}
Add named fw_cfg entry with contents from string @var{str}.

The terminating NUL character of the contents of @var{str} will not be
included as part of the fw_cfg item data. To insert contents with
embedded NUL characters, you have to use the @var{file} parameter.

The fw_cfg entries are passed by QEMU through to the guest.

Example:
@example
    -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
@end example
creates an fw_cfg entry named opt/com.mycompany/blob with contents
from ./my_blob.bin.

ETEXI
SRST
``-fw_cfg [name=]name,file=file``
    Add named fw\_cfg entry with contents from file file.

``-fw_cfg [name=]name,string=str``
    Add named fw\_cfg entry with contents from string str.

    The terminating NUL character of the contents of str will not be
    included as part of the fw\_cfg item data. To insert contents with
    embedded NUL characters, you have to use the file parameter.

    The fw\_cfg entries are passed by QEMU through to the guest.

    Example:

    ::

            -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin

    creates an fw\_cfg entry named opt/com.mycompany/blob with contents
    from ./my\_blob.bin.
ERST

DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
    "-serial dev     redirect the serial port to char device 'dev'\n",
    QEMU_ARCH_ALL)
STEXI
@item -serial @var{dev}
@findex -serial
Redirect the virtual serial port to host character device
@var{dev}. The default device is @code{vc} in graphical mode and
@code{stdio} in non graphical mode.

This option can be used several times to simulate up to 4 serial
ports.

Use @code{-serial none} to disable all serial ports.

Available character devices are:
@table @option
@item vc[:@var{W}x@var{H}]
Virtual console. Optionally, a width and height can be given in pixel with
@example
vc:800x600
@end example
It is also possible to specify width or height in characters:
@example
vc:80Cx24C
@end example
@item pty
[Linux only] Pseudo TTY (a new PTY is automatically allocated)
@item none
No device is allocated.
@item null
void device
@item chardev:@var{id}
Use a named character device defined with the @code{-chardev} option.
@item /dev/XXX
[Linux only] Use host tty, e.g. @file{/dev/ttyS0}. The host serial port
parameters are set according to the emulated ones.
@item /dev/parport@var{N}
[Linux only, parallel port only] Use host parallel port
@var{N}. Currently SPP and EPP parallel port features can be used.
@item file:@var{filename}
Write output to @var{filename}. No character can be read.
@item stdio
[Unix only] standard input/output
@item pipe:@var{filename}
name pipe @var{filename}
@item COM@var{n}
[Windows only] Use host serial port @var{n}
@item udp:[@var{remote_host}]:@var{remote_port}[@@[@var{src_ip}]:@var{src_port}]
This implements UDP Net Console.
When @var{remote_host} or @var{src_ip} are not specified
they default to @code{0.0.0.0}.
When not using a specified @var{src_port} a random port is automatically chosen.

If you just want a simple readonly console you can use @code{netcat} or
@code{nc}, by starting QEMU with: @code{-serial udp::4555} and nc as:
@code{nc -u -l -p 4555}. Any time QEMU writes something to that port it
will appear in the netconsole session.

If you plan to send characters back via netconsole or you want to stop
and start QEMU a lot of times, you should have QEMU use the same
source port each time by using something like @code{-serial
udp::4555@@:4556} to QEMU. Another approach is to use a patched
version of netcat which can listen to a TCP port and send and receive
characters via udp.  If you have a patched version of netcat which
activates telnet remote echo and single char transfer, then you can
use the following options to set up a netcat redirector to allow
telnet on port 5555 to access the QEMU port.
@table @code
@item QEMU Options:
-serial udp::4555@@:4556
@item netcat options:
-u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
@item telnet options:
localhost 5555
@end table

@item tcp:[@var{host}]:@var{port}[,@var{server}][,nowait][,nodelay][,reconnect=@var{seconds}]
The TCP Net Console has two modes of operation.  It can send the serial
I/O to a location or wait for a connection from a location.  By default
the TCP Net Console is sent to @var{host} at the @var{port}.  If you use
the @var{server} option QEMU will wait for a client socket application
to connect to the port before continuing, unless the @code{nowait}
option was specified.  The @code{nodelay} option disables the Nagle buffering
algorithm.  The @code{reconnect} option only applies if @var{noserver} is
set, if the connection goes down it will attempt to reconnect at the
given interval.  If @var{host} is omitted, 0.0.0.0 is assumed. Only
one TCP connection at a time is accepted. You can use @code{telnet} to
connect to the corresponding character device.
@table @code
@item Example to send tcp console to 192.168.0.2 port 4444
-serial tcp:192.168.0.2:4444
@item Example to listen and wait on port 4444 for connection
-serial tcp::4444,server
@item Example to not wait and listen on ip 192.168.0.100 port 4444
-serial tcp:192.168.0.100:4444,server,nowait
@end table

@item telnet:@var{host}:@var{port}[,server][,nowait][,nodelay]
The telnet protocol is used instead of raw tcp sockets.  The options
work the same as if you had specified @code{-serial tcp}.  The
difference is that the port acts like a telnet server or client using
telnet option negotiation.  This will also allow you to send the
MAGIC_SYSRQ sequence if you use a telnet that supports sending the break
sequence.  Typically in unix telnet you do it with Control-] and then
type "send break" followed by pressing the enter key.

@item websocket:@var{host}:@var{port},server[,nowait][,nodelay]
The WebSocket protocol is used instead of raw tcp socket. The port acts as
a WebSocket server. Client mode is not supported.

@item unix:@var{path}[,server][,nowait][,reconnect=@var{seconds}]
A unix domain socket is used instead of a tcp socket.  The option works the
same as if you had specified @code{-serial tcp} except the unix domain socket
@var{path} is used for connections.

@item mon:@var{dev_string}
This is a special option to allow the monitor to be multiplexed onto
another serial port.  The monitor is accessed with key sequence of
@key{Control-a} and then pressing @key{c}.
@var{dev_string} should be any one of the serial devices specified
above.  An example to multiplex the monitor onto a telnet server
listening on port 4444 would be:
@table @code
@item -serial mon:telnet::4444,server,nowait
@end table
When the monitor is multiplexed to stdio in this way, Ctrl+C will not terminate
QEMU any more but will be passed to the guest instead.

@item braille
Braille device.  This will use BrlAPI to display the braille output on a real
or fake device.

@item msmouse
Three button serial mouse. Configure the guest to use Microsoft protocol.
@end table
ETEXI
SRST
``-serial dev``
    Redirect the virtual serial port to host character device dev. The
    default device is ``vc`` in graphical mode and ``stdio`` in non
    graphical mode.

    This option can be used several times to simulate up to 4 serial
    ports.

    Use ``-serial none`` to disable all serial ports.

    Available character devices are:

    ``vc[:WxH]``
        Virtual console. Optionally, a width and height can be given in
        pixel with

        ::

            vc:800x600

        It is also possible to specify width or height in characters:

        ::

            vc:80Cx24C

    ``pty``
        [Linux only] Pseudo TTY (a new PTY is automatically allocated)

    ``none``
        No device is allocated.

    ``null``
        void device

    ``chardev:id``
        Use a named character device defined with the ``-chardev``
        option.

    ``/dev/XXX``
        [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
        port parameters are set according to the emulated ones.

    ``/dev/parportN``
        [Linux only, parallel port only] Use host parallel port N.
        Currently SPP and EPP parallel port features can be used.

    ``file:filename``
        Write output to filename. No character can be read.

    ``stdio``
        [Unix only] standard input/output

    ``pipe:filename``
        name pipe filename

    ``COMn``
        [Windows only] Use host serial port n

    ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
        This implements UDP Net Console. When remote\_host or src\_ip
        are not specified they default to ``0.0.0.0``. When not using a
        specified src\_port a random port is automatically chosen.

        If you just want a simple readonly console you can use
        ``netcat`` or ``nc``, by starting QEMU with:
        ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
        QEMU writes something to that port it will appear in the
        netconsole session.

        If you plan to send characters back via netconsole or you want
        to stop and start QEMU a lot of times, you should have QEMU use
        the same source port each time by using something like ``-serial
        udp::4555@:4556`` to QEMU. Another approach is to use a patched
        version of netcat which can listen to a TCP port and send and
        receive characters via udp. If you have a patched version of
        netcat which activates telnet remote echo and single char
        transfer, then you can use the following options to set up a
        netcat redirector to allow telnet on port 5555 to access the
        QEMU port.

        ``QEMU Options:``
            -serial udp::4555@:4556

        ``netcat options:``
            -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T

        ``telnet options:``
            localhost 5555

    ``tcp:[host]:port[,server][,nowait][,nodelay][,reconnect=seconds]``
        The TCP Net Console has two modes of operation. It can send the
        serial I/O to a location or wait for a connection from a
        location. By default the TCP Net Console is sent to host at the
        port. If you use the server option QEMU will wait for a client
        socket application to connect to the port before continuing,
        unless the ``nowait`` option was specified. The ``nodelay``
        option disables the Nagle buffering algorithm. The ``reconnect``
        option only applies if noserver is set, if the connection goes
        down it will attempt to reconnect at the given interval. If host
        is omitted, 0.0.0.0 is assumed. Only one TCP connection at a
        time is accepted. You can use ``telnet`` to connect to the
        corresponding character device.

        ``Example to send tcp console to 192.168.0.2 port 4444``
            -serial tcp:192.168.0.2:4444

        ``Example to listen and wait on port 4444 for connection``
            -serial tcp::4444,server

        ``Example to not wait and listen on ip 192.168.0.100 port 4444``
            -serial tcp:192.168.0.100:4444,server,nowait

    ``telnet:host:port[,server][,nowait][,nodelay]``
        The telnet protocol is used instead of raw tcp sockets. The
        options work the same as if you had specified ``-serial tcp``.
        The difference is that the port acts like a telnet server or
        client using telnet option negotiation. This will also allow you
        to send the MAGIC\_SYSRQ sequence if you use a telnet that
        supports sending the break sequence. Typically in unix telnet
        you do it with Control-] and then type "send break" followed by
        pressing the enter key.

    ``websocket:host:port,server[,nowait][,nodelay]``
        The WebSocket protocol is used instead of raw tcp socket. The
        port acts as a WebSocket server. Client mode is not supported.

    ``unix:path[,server][,nowait][,reconnect=seconds]``
        A unix domain socket is used instead of a tcp socket. The option
        works the same as if you had specified ``-serial tcp`` except
        the unix domain socket path is used for connections.

    ``mon:dev_string``
        This is a special option to allow the monitor to be multiplexed
        onto another serial port. The monitor is accessed with key
        sequence of Control-a and then pressing c. dev\_string should be
        any one of the serial devices specified above. An example to
        multiplex the monitor onto a telnet server listening on port
        4444 would be:

        ``-serial mon:telnet::4444,server,nowait``

        When the monitor is multiplexed to stdio in this way, Ctrl+C
        will not terminate QEMU any more but will be passed to the guest
        instead.

    ``braille``
        Braille device. This will use BrlAPI to display the braille
        output on a real or fake device.

    ``msmouse``
        Three button serial mouse. Configure the guest to use Microsoft
        protocol.
ERST

DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
    "-parallel dev   redirect the parallel port to char device 'dev'\n",
    QEMU_ARCH_ALL)
STEXI
@item -parallel @var{dev}
@findex -parallel
Redirect the virtual parallel port to host device @var{dev} (same
devices as the serial port). On Linux hosts, @file{/dev/parportN} can
be used to use hardware devices connected on the corresponding host
parallel port.

This option can be used several times to simulate up to 3 parallel
ports.

Use @code{-parallel none} to disable all parallel ports.
ETEXI
SRST
``-parallel dev``
    Redirect the virtual parallel port to host device dev (same devices
    as the serial port). On Linux hosts, ``/dev/parportN`` can be used
    to use hardware devices connected on the corresponding host parallel
    port.

    This option can be used several times to simulate up to 3 parallel
    ports.

    Use ``-parallel none`` to disable all parallel ports.
ERST

DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
    "-monitor dev    redirect the monitor to char device 'dev'\n",
    QEMU_ARCH_ALL)
STEXI
@item -monitor @var{dev}
@findex -monitor
Redirect the monitor to host device @var{dev} (same devices as the
serial port).
The default device is @code{vc} in graphical mode and @code{stdio} in
non graphical mode.
Use @code{-monitor none} to disable the default monitor.
ETEXI
SRST
``-monitor dev``
    Redirect the monitor to host device dev (same devices as the serial
    port). The default device is ``vc`` in graphical mode and ``stdio``
    in non graphical mode. Use ``-monitor none`` to disable the default
    monitor.
ERST
DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
    "-qmp dev        like -monitor but opens in 'control' mode\n",
    QEMU_ARCH_ALL)
STEXI
@item -qmp @var{dev}
@findex -qmp
Like -monitor but opens in 'control' mode.
ETEXI
SRST
``-qmp dev``
    Like -monitor but opens in 'control' mode.
ERST
DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
    "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
    QEMU_ARCH_ALL)
STEXI
@item -qmp-pretty @var{dev}
@findex -qmp-pretty
Like -qmp but uses pretty JSON formatting.
ETEXI
SRST
``-qmp-pretty dev``
    Like -qmp but uses pretty JSON formatting.
ERST

DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
    "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
STEXI
@item -mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]
@findex -mon
Setup monitor on chardev @var{name}. @code{pretty} turns on JSON pretty printing
easing human reading and debugging.
ETEXI
SRST
``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
    Setup monitor on chardev name. ``pretty`` turns on JSON pretty
    printing easing human reading and debugging.
ERST

DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
    "-debugcon dev   redirect the debug console to char device 'dev'\n",
    QEMU_ARCH_ALL)
STEXI
@item -debugcon @var{dev}
@findex -debugcon
Redirect the debug console to host device @var{dev} (same devices as the
serial port).  The debug console is an I/O port which is typically port
0xe9; writing to that I/O port sends output to this device.
The default device is @code{vc} in graphical mode and @code{stdio} in
non graphical mode.
ETEXI
SRST
``-debugcon dev``
    Redirect the debug console to host device dev (same devices as the
    serial port). The debug console is an I/O port which is typically
    port 0xe9; writing to that I/O port sends output to this device. The
    default device is ``vc`` in graphical mode and ``stdio`` in non
    graphical mode.
ERST

DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
    "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
STEXI
@item -pidfile @var{file}
@findex -pidfile
Store the QEMU process PID in @var{file}. It is useful if you launch QEMU
from a script.
ETEXI
SRST
``-pidfile file``
    Store the QEMU process PID in file. It is useful if you launch QEMU
    from a script.
ERST

DEF("singlestep", 0, QEMU_OPTION_singlestep, \
    "-singlestep     always run in singlestep mode\n", QEMU_ARCH_ALL)
STEXI
@item -singlestep
@findex -singlestep
Run the emulation in single step mode.
ETEXI
SRST
``-singlestep``
    Run the emulation in single step mode.
ERST

DEF("preconfig", 0, QEMU_OPTION_preconfig, \
    "--preconfig     pause QEMU before machine is initialized (experimental)\n",
    QEMU_ARCH_ALL)
STEXI
@item --preconfig
@findex --preconfig
Pause QEMU for interactive configuration before the machine is created,
which allows querying and configuring properties that will affect
machine initialization.  Use QMP command 'x-exit-preconfig' to exit
the preconfig state and move to the next state (i.e. run guest if -S
isn't used or pause the second time if -S is used).  This option is
experimental.
ETEXI
SRST
``--preconfig``
    Pause QEMU for interactive configuration before the machine is
    created, which allows querying and configuring properties that will
    affect machine initialization. Use QMP command 'x-exit-preconfig' to
    exit the preconfig state and move to the next state (i.e. run guest
    if -S isn't used or pause the second time if -S is used). This
    option is experimental.
ERST

DEF("S", 0, QEMU_OPTION_S, \
    "-S              freeze CPU at startup (use 'c' to start execution)\n",
    QEMU_ARCH_ALL)
STEXI
@item -S
@findex -S
Do not start CPU at startup (you must type 'c' in the monitor).
ETEXI
SRST
``-S``
    Do not start CPU at startup (you must type 'c' in the monitor).
ERST

DEF("realtime", HAS_ARG, QEMU_OPTION_realtime,
    "-realtime [mlock=on|off]\n"
    "                run qemu with realtime features\n"
    "                mlock=on|off controls mlock support (default: on)\n",
    QEMU_ARCH_ALL)
STEXI
@item -realtime mlock=on|off
@findex -realtime
Run qemu with realtime features.
mlocking qemu and guest memory can be enabled via @option{mlock=on}
(enabled by default).
ETEXI
SRST
``-realtime mlock=on|off``
    Run qemu with realtime features. mlocking qemu and guest memory can
    be enabled via ``mlock=on`` (enabled by default).
ERST

DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
    "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
    "                run qemu with overcommit hints\n"
    "                mem-lock=on|off controls memory lock support (default: off)\n"
    "                cpu-pm=on|off controls cpu power management (default: off)\n",
    QEMU_ARCH_ALL)
STEXI
@item -overcommit mem-lock=on|off
@item -overcommit cpu-pm=on|off
@findex -overcommit
Run qemu with hints about host resource overcommit. The default is
to assume that host overcommits all resources.

Locking qemu and guest memory can be enabled via @option{mem-lock=on} (disabled
by default).  This works when host memory is not overcommitted and reduces the
worst-case latency for guest.  This is equivalent to @option{realtime}.

Guest ability to manage power state of host cpus (increasing latency for other
processes on the same host cpu, but decreasing latency for guest) can be
enabled via @option{cpu-pm=on} (disabled by default).  This works best when
host CPU is not overcommitted. When used, host estimates of CPU cycle and power
utilization will be incorrect, not taking into account guest idle time.
ETEXI
SRST
``-overcommit mem-lock=on|off``
``-overcommit cpu-pm=on|off``
    Run qemu with hints about host resource overcommit. The default is
    to assume that host overcommits all resources.

    Locking qemu and guest memory can be enabled via ``mem-lock=on``
    (disabled by default). This works when host memory is not
    overcommitted and reduces the worst-case latency for guest. This is
    equivalent to ``realtime``.

    Guest ability to manage power state of host cpus (increasing latency
    for other processes on the same host cpu, but decreasing latency for
    guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
    works best when host CPU is not overcommitted. When used, host
    estimates of CPU cycle and power utilization will be incorrect, not
    taking into account guest idle time.
ERST

DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
    "-gdb dev        wait for gdb connection on 'dev'\n", QEMU_ARCH_ALL)
STEXI
@item -gdb @var{dev}
@findex -gdb
Wait for gdb connection on device @var{dev} (@pxref{gdb_usage}). Typical
connections will likely be TCP-based, but also UDP, pseudo TTY, or even
stdio are reasonable use case. The latter is allowing to start QEMU from
within gdb and establish the connection via a pipe:
@example
(gdb) target remote | exec @value{qemu_system} -gdb stdio ...
@end example
ETEXI
SRST
``-gdb dev``
    Wait for gdb connection on device dev (see
    :ref:`gdb_005fusage`). Typical connections will likely be
    TCP-based, but also UDP, pseudo TTY, or even stdio are reasonable
    use case. The latter is allowing to start QEMU from within gdb and
    establish the connection via a pipe:

    ::

        (gdb) target remote | exec |qemu_system| -gdb stdio ...
ERST

DEF("s", 0, QEMU_OPTION_s, \
    "-s              shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
    QEMU_ARCH_ALL)
STEXI
@item -s
@findex -s
Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
(@pxref{gdb_usage}).
ETEXI
SRST
``-s``
    Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
    (see :ref:`gdb_005fusage`).
ERST

DEF("d", HAS_ARG, QEMU_OPTION_d, \
    "-d item1,...    enable logging of specified items (use '-d help' for a list of log items)\n",
    QEMU_ARCH_ALL)
STEXI
@item -d @var{item1}[,...]
@findex -d
Enable logging of specified items. Use '-d help' for a list of log items.
ETEXI
SRST
``-d item1[,...]``
    Enable logging of specified items. Use '-d help' for a list of log
    items.
ERST

DEF("D", HAS_ARG, QEMU_OPTION_D, \
    "-D logfile      output log to logfile (default stderr)\n",
    QEMU_ARCH_ALL)
STEXI
@item -D @var{logfile}
@findex -D
Output log in @var{logfile} instead of to stderr
ETEXI
SRST
``-D logfile``
    Output log in logfile instead of to stderr
ERST

DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
    "-dfilter range,..  filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
    QEMU_ARCH_ALL)
STEXI
@item -dfilter @var{range1}[,...]
@findex -dfilter
Filter debug output to that relevant to a range of target addresses. The filter
spec can be either @var{start}+@var{size}, @var{start}-@var{size} or
@var{start}..@var{end} where @var{start} @var{end} and @var{size} are the
addresses and sizes required. For example:
@example
    -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
@end example
Will dump output for any code in the 0x1000 sized block starting at 0x8000 and
the 0x200 sized block starting at 0xffffffc000080000 and another 0x1000 sized
block starting at 0xffffffc00005f000.
ETEXI
SRST
``-dfilter range1[,...]``
    Filter debug output to that relevant to a range of target addresses.
    The filter spec can be either start+size, start-size or start..end
    where start end and size are the addresses and sizes required. For
    example:

    ::

            -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000

    Will dump output for any code in the 0x1000 sized block starting at
    0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
    another 0x1000 sized block starting at 0xffffffc00005f000.
ERST

DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
    "-seed number       seed the pseudo-random number generator\n",
    QEMU_ARCH_ALL)
STEXI
@item -seed @var{number}
@findex -seed
Force the guest to use a deterministic pseudo-random number generator, seeded
with @var{number}.  This does not affect crypto routines within the host.
ETEXI
SRST
``-seed number``
    Force the guest to use a deterministic pseudo-random number
    generator, seeded with number. This does not affect crypto routines
    within the host.
ERST

DEF("L", HAS_ARG, QEMU_OPTION_L, \
    "-L path         set the directory for the BIOS, VGA BIOS and keymaps\n",
    QEMU_ARCH_ALL)
STEXI
@item -L  @var{path}
@findex -L
Set the directory for the BIOS, VGA BIOS and keymaps.

To list all the data directories, use @code{-L help}.
ETEXI
SRST
``-L  path``
    Set the directory for the BIOS, VGA BIOS and keymaps.

    To list all the data directories, use ``-L help``.
ERST

DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
    "-bios file      set the filename for the BIOS\n", QEMU_ARCH_ALL)
STEXI
@item -bios @var{file}
@findex -bios
Set the filename for the BIOS.
ETEXI
SRST
``-bios file``
    Set the filename for the BIOS.
ERST

DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
    "-enable-kvm     enable KVM full virtualization support\n", QEMU_ARCH_ALL)
STEXI
@item -enable-kvm
@findex -enable-kvm
Enable KVM full virtualization support. This option is only available
if KVM support is enabled when compiling.
ETEXI
SRST
``-enable-kvm``
    Enable KVM full virtualization support. This option is only
    available if KVM support is enabled when compiling.
ERST

DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
    "-xen-domid id   specify xen guest domain id\n", QEMU_ARCH_ALL)
DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
    "-xen-attach     attach to existing xen domain\n"
    "                libxl will use this when starting QEMU\n",
    QEMU_ARCH_ALL)
DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
    "-xen-domid-restrict     restrict set of available xen operations\n"
    "                        to specified domain id. (Does not affect\n"
    "                        xenpv machine type).\n",
    QEMU_ARCH_ALL)
STEXI
@item -xen-domid @var{id}
@findex -xen-domid
Specify xen guest domain @var{id} (XEN only).
@item -xen-attach
@findex -xen-attach
Attach to existing xen domain.
libxl will use this when starting QEMU (XEN only).
@findex -xen-domid-restrict
Restrict set of available xen operations to specified domain id (XEN only).
ETEXI
SRST
``-xen-domid id``
    Specify xen guest domain id (XEN only).

``-xen-attach``
    Attach to existing xen domain. libxl will use this when starting
    QEMU (XEN only). Restrict set of available xen operations to
    specified domain id (XEN only).
ERST

DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
    "-no-reboot      exit instead of rebooting\n", QEMU_ARCH_ALL)
STEXI
@item -no-reboot
@findex -no-reboot
Exit instead of rebooting.
ETEXI
SRST
``-no-reboot``
    Exit instead of rebooting.
ERST

DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
    "-no-shutdown    stop before shutdown\n", QEMU_ARCH_ALL)
STEXI
@item -no-shutdown
@findex -no-shutdown
Don't exit QEMU on guest shutdown, but instead only stop the emulation.
This allows for instance switching to monitor to commit changes to the
disk image.
ETEXI
SRST
``-no-shutdown``
    Don't exit QEMU on guest shutdown, but instead only stop the
    emulation. This allows for instance switching to monitor to commit
    changes to the disk image.
ERST

DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
    "-loadvm [tag|id]\n" \
    "                start right away with a saved state (loadvm in monitor)\n",
    QEMU_ARCH_ALL)
STEXI
@item -loadvm @var{file}
@findex -loadvm
Start right away with a saved state (@code{loadvm} in monitor)
ETEXI
SRST
``-loadvm file``
    Start right away with a saved state (``loadvm`` in monitor)
ERST

#ifndef _WIN32
DEF("daemonize", 0, QEMU_OPTION_daemonize, \
    "-daemonize      daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
#endif
STEXI
@item -daemonize
@findex -daemonize
Daemonize the QEMU process after initialization.  QEMU will not detach from
standard IO until it is ready to receive connections on any of its devices.
This option is a useful way for external programs to launch QEMU without having
to cope with initialization race conditions.
ETEXI
SRST
``-daemonize``
    Daemonize the QEMU process after initialization. QEMU will not
    detach from standard IO until it is ready to receive connections on
    any of its devices. This option is a useful way for external
    programs to launch QEMU without having to cope with initialization
    race conditions.
ERST

DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
    "-option-rom rom load a file, rom, into the option ROM space\n",
    QEMU_ARCH_ALL)
STEXI
@item -option-rom @var{file}
@findex -option-rom
Load the contents of @var{file} as an option ROM.
This option is useful to load things like EtherBoot.
ETEXI
SRST
``-option-rom file``
    Load the contents of file as an option ROM. This option is useful to
    load things like EtherBoot.
ERST

DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
    "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
    "                set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
    QEMU_ARCH_ALL)

STEXI

@item -rtc [base=utc|localtime|@var{datetime}][,clock=host|rt|vm][,driftfix=none|slew]
@findex -rtc
Specify @option{base} as @code{utc} or @code{localtime} to let the RTC start at the current
UTC or local time, respectively. @code{localtime} is required for correct date in
MS-DOS or Windows. To start at a specific point in time, provide @var{datetime} in the
format @code{2006-06-17T16:01:21} or @code{2006-06-17}. The default base is UTC.

By default the RTC is driven by the host system time. This allows using of the
RTC as accurate reference clock inside the guest, specifically if the host
time is smoothly following an accurate external reference clock, e.g. via NTP.
If you want to isolate the guest time from the host, you can set @option{clock}
to @code{rt} instead, which provides a host monotonic clock if host support it.
To even prevent the RTC from progressing during suspension, you can set @option{clock}
to @code{vm} (virtual clock). @samp{clock=vm} is recommended especially in
icount mode in order to preserve determinism; however, note that in icount mode
the speed of the virtual clock is variable and can in general differ from the
host clock.

Enable @option{driftfix} (i386 targets only) if you experience time drift problems,
specifically with Windows' ACPI HAL. This option will try to figure out how
many timer interrupts were not processed by the Windows guest and will
re-inject them.
ETEXI
SRST
``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
    Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
    the current UTC or local time, respectively. ``localtime`` is
    required for correct date in MS-DOS or Windows. To start at a
    specific point in time, provide datetime in the format
    ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.

    By default the RTC is driven by the host system time. This allows
    using of the RTC as accurate reference clock inside the guest,
    specifically if the host time is smoothly following an accurate
    external reference clock, e.g. via NTP. If you want to isolate the
    guest time from the host, you can set ``clock`` to ``rt`` instead,
    which provides a host monotonic clock if host support it. To even
    prevent the RTC from progressing during suspension, you can set
    ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
    recommended especially in icount mode in order to preserve
    determinism; however, note that in icount mode the speed of the
    virtual clock is variable and can in general differ from the host
    clock.

    Enable ``driftfix`` (i386 targets only) if you experience time drift
    problems, specifically with Windows' ACPI HAL. This option will try
    to figure out how many timer interrupts were not processed by the
    Windows guest and will re-inject them.
ERST

DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
    "-icount [shift=N|auto][,align=on|off][,sleep=on|off,rr=record|replay,rrfile=<filename>,rrsnapshot=<snapshot>]\n" \
    "                enable virtual instruction counter with 2^N clock ticks per\n" \
    "                instruction, enable aligning the host and virtual clocks\n" \
    "                or disable real time cpu sleeping\n", QEMU_ARCH_ALL)
STEXI
@item -icount [shift=@var{N}|auto][,rr=record|replay,rrfile=@var{filename},rrsnapshot=@var{snapshot}]
@findex -icount
Enable virtual instruction counter.  The virtual cpu will execute one
instruction every 2^@var{N} ns of virtual time.  If @code{auto} is specified
then the virtual cpu speed will be automatically adjusted to keep virtual
time within a few seconds of real time.

When the virtual cpu is sleeping, the virtual time will advance at default
speed unless @option{sleep=on|off} is specified.
With @option{sleep=on|off}, the virtual time will jump to the next timer deadline
instantly whenever the virtual cpu goes to sleep mode and will not advance
if no timer is enabled. This behavior give deterministic execution times from
the guest point of view.

Note that while this option can give deterministic behavior, it does not
provide cycle accurate emulation.  Modern CPUs contain superscalar out of
order cores with complex cache hierarchies.  The number of instructions
executed often has little or no correlation with actual performance.

@option{align=on} will activate the delay algorithm which will try
to synchronise the host clock and the virtual clock. The goal is to
have a guest running at the real frequency imposed by the shift option.
Whenever the guest clock is behind the host clock and if
@option{align=on} is specified then we print a message to the user
to inform about the delay.
Currently this option does not work when @option{shift} is @code{auto}.
Note: The sync algorithm will work for those shift values for which
the guest clock runs ahead of the host clock. Typically this happens
when the shift value is high (how high depends on the host machine).

When @option{rr} option is specified deterministic record/replay is enabled.
Replay log is written into @var{filename} file in record mode and
read from this file in replay mode.

Option rrsnapshot is used to create new vm snapshot named @var{snapshot}
at the start of execution recording. In replay mode this option is used
to load the initial VM state.
ETEXI
SRST
``-icount [shift=N|auto][,rr=record|replay,rrfile=filename,rrsnapshot=snapshot]``
    Enable virtual instruction counter. The virtual cpu will execute one
    instruction every 2^N ns of virtual time. If ``auto`` is specified
    then the virtual cpu speed will be automatically adjusted to keep
    virtual time within a few seconds of real time.

    When the virtual cpu is sleeping, the virtual time will advance at
    default speed unless ``sleep=on|off`` is specified. With
    ``sleep=on|off``, the virtual time will jump to the next timer
    deadline instantly whenever the virtual cpu goes to sleep mode and
    will not advance if no timer is enabled. This behavior give
    deterministic execution times from the guest point of view.

    Note that while this option can give deterministic behavior, it does
    not provide cycle accurate emulation. Modern CPUs contain
    superscalar out of order cores with complex cache hierarchies. The
    number of instructions executed often has little or no correlation
    with actual performance.

    ``align=on`` will activate the delay algorithm which will try to
    synchronise the host clock and the virtual clock. The goal is to
    have a guest running at the real frequency imposed by the shift
    option. Whenever the guest clock is behind the host clock and if
    ``align=on`` is specified then we print a message to the user to
    inform about the delay. Currently this option does not work when
    ``shift`` is ``auto``. Note: The sync algorithm will work for those
    shift values for which the guest clock runs ahead of the host clock.
    Typically this happens when the shift value is high (how high
    depends on the host machine).

    When ``rr`` option is specified deterministic record/replay is
    enabled. Replay log is written into filename file in record mode and
    read from this file in replay mode.

    Option rrsnapshot is used to create new vm snapshot named snapshot
    at the start of execution recording. In replay mode this option is
    used to load the initial VM state.
ERST

DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
    "-watchdog model\n" \
    "                enable virtual hardware watchdog [default=none]\n",
    QEMU_ARCH_ALL)
STEXI
@item -watchdog @var{model}
@findex -watchdog
Create a virtual hardware watchdog device.  Once enabled (by a guest
action), the watchdog must be periodically polled by an agent inside
the guest or else the guest will be restarted. Choose a model for
which your guest has drivers.

The @var{model} is the model of hardware watchdog to emulate. Use
@code{-watchdog help} to list available hardware models. Only one
watchdog can be enabled for a guest.

The following models may be available:
@table @option
@item ib700
iBASE 700 is a very simple ISA watchdog with a single timer.
@item i6300esb
Intel 6300ESB I/O controller hub is a much more featureful PCI-based
dual-timer watchdog.
@item diag288
A virtual watchdog for s390x backed by the diagnose 288 hypercall
(currently KVM only).
@end table
ETEXI
SRST
``-watchdog model``
    Create a virtual hardware watchdog device. Once enabled (by a guest
    action), the watchdog must be periodically polled by an agent inside
    the guest or else the guest will be restarted. Choose a model for
    which your guest has drivers.

    The model is the model of hardware watchdog to emulate. Use
    ``-watchdog help`` to list available hardware models. Only one
    watchdog can be enabled for a guest.

    The following models may be available:

    ``ib700``
        iBASE 700 is a very simple ISA watchdog with a single timer.

    ``i6300esb``
        Intel 6300ESB I/O controller hub is a much more featureful
        PCI-based dual-timer watchdog.

    ``diag288``
        A virtual watchdog for s390x backed by the diagnose 288
        hypercall (currently KVM only).
ERST

DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
    "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
    "                action when watchdog fires [default=reset]\n",
    QEMU_ARCH_ALL)
STEXI
@item -watchdog-action @var{action}
@findex -watchdog-action

The @var{action} controls what QEMU will do when the watchdog timer
expires.
The default is
@code{reset} (forcefully reset the guest).
Other possible actions are:
@code{shutdown} (attempt to gracefully shutdown the guest),
@code{poweroff} (forcefully poweroff the guest),
@code{inject-nmi} (inject a NMI into the guest),
@code{pause} (pause the guest),
@code{debug} (print a debug message and continue), or
@code{none} (do nothing).

Note that the @code{shutdown} action requires that the guest responds
to ACPI signals, which it may not be able to do in the sort of
situations where the watchdog would have expired, and thus
@code{-watchdog-action shutdown} is not recommended for production use.

Examples:

@table @code
@item -watchdog i6300esb -watchdog-action pause
@itemx -watchdog ib700
@end table
ETEXI
SRST
``-watchdog-action action``
    The action controls what QEMU will do when the watchdog timer
    expires. The default is ``reset`` (forcefully reset the guest).
    Other possible actions are: ``shutdown`` (attempt to gracefully
    shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
    ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
    guest), ``debug`` (print a debug message and continue), or ``none``
    (do nothing).

    Note that the ``shutdown`` action requires that the guest responds
    to ACPI signals, which it may not be able to do in the sort of
    situations where the watchdog would have expired, and thus
    ``-watchdog-action shutdown`` is not recommended for production use.

    Examples:

    ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700``

ERST

DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
    "-echr chr       set terminal escape character instead of ctrl-a\n",
    QEMU_ARCH_ALL)
STEXI

@item -echr @var{numeric_ascii_value}
@findex -echr
Change the escape character used for switching to the monitor when using
monitor and serial sharing.  The default is @code{0x01} when using the
@code{-nographic} option.  @code{0x01} is equal to pressing
@code{Control-a}.  You can select a different character from the ascii
control keys where 1 through 26 map to Control-a through Control-z.  For
instance you could use the either of the following to change the escape
character to Control-t.
@table @code
@item -echr 0x14
@itemx -echr 20
@end table
ETEXI
SRST
``-echr numeric_ascii_value``
    Change the escape character used for switching to the monitor when
    using monitor and serial sharing. The default is ``0x01`` when using
    the ``-nographic`` option. ``0x01`` is equal to pressing
    ``Control-a``. You can select a different character from the ascii
    control keys where 1 through 26 map to Control-a through Control-z.
    For instance you could use the either of the following to change the
    escape character to Control-t.

    ``-echr 0x14``; \ ``-echr 20``

ERST

DEF("show-cursor", 0, QEMU_OPTION_show_cursor, \
    "-show-cursor    show cursor\n", QEMU_ARCH_ALL)
STEXI
@item -show-cursor
@findex -show-cursor
Show cursor.
ETEXI
SRST
``-show-cursor``
    Show cursor.
ERST

DEF("tb-size", HAS_ARG, QEMU_OPTION_tb_size, \
    "-tb-size n      set TB size\n", QEMU_ARCH_ALL)
STEXI
@item -tb-size @var{n}
@findex -tb-size
Set TCG translation block cache size.  Deprecated, use @samp{-accel tcg,tb-size=@var{n}}
instead.
ETEXI
SRST
``-tb-size n``
    Set TCG translation block cache size. Deprecated, use
    '\ ``-accel tcg,tb-size=n``\ ' instead.
ERST

DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
    "-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]\n" \
    "-incoming rdma:host:port[,ipv4][,ipv6]\n" \
    "-incoming unix:socketpath\n" \
    "                prepare for incoming migration, listen on\n" \
    "                specified protocol and socket address\n" \
    "-incoming fd:fd\n" \
    "-incoming exec:cmdline\n" \
    "                accept incoming migration on given file descriptor\n" \
    "                or from given external command\n" \
    "-incoming defer\n" \
    "                wait for the URI to be specified via migrate_incoming\n",
    QEMU_ARCH_ALL)
STEXI
@item -incoming tcp:[@var{host}]:@var{port}[,to=@var{maxport}][,ipv4][,ipv6]
@itemx -incoming rdma:@var{host}:@var{port}[,ipv4][,ipv6]
@findex -incoming
Prepare for incoming migration, listen on a given tcp port.

@item -incoming unix:@var{socketpath}
Prepare for incoming migration, listen on a given unix socket.

@item -incoming fd:@var{fd}
Accept incoming migration from a given filedescriptor.

@item -incoming exec:@var{cmdline}
Accept incoming migration as an output from specified external command.

@item -incoming defer
Wait for the URI to be specified via migrate_incoming.  The monitor can
be used to change settings (such as migration parameters) prior to issuing
the migrate_incoming to allow the migration to begin.
ETEXI
SRST
``-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]``; \ ``-incoming rdma:host:port[,ipv4][,ipv6]``
    Prepare for incoming migration, listen on a given tcp port.

``-incoming unix:socketpath``
    Prepare for incoming migration, listen on a given unix socket.

``-incoming fd:fd``
    Accept incoming migration from a given filedescriptor.

``-incoming exec:cmdline``
    Accept incoming migration as an output from specified external
    command.

``-incoming defer``
    Wait for the URI to be specified via migrate\_incoming. The monitor
    can be used to change settings (such as migration parameters) prior
    to issuing the migrate\_incoming to allow the migration to begin.
ERST

DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
    "-only-migratable     allow only migratable devices\n", QEMU_ARCH_ALL)
STEXI
@item -only-migratable
@findex -only-migratable
Only allow migratable devices. Devices will not be allowed to enter an
unmigratable state.
ETEXI
SRST
``-only-migratable``
    Only allow migratable devices. Devices will not be allowed to enter
    an unmigratable state.
ERST

DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
    "-nodefaults     don't create default devices\n", QEMU_ARCH_ALL)
STEXI
@item -nodefaults
@findex -nodefaults
Don't create default devices. Normally, QEMU sets the default devices like serial
port, parallel port, virtual console, monitor device, VGA adapter, floppy and
CD-ROM drive and others. The @code{-nodefaults} option will disable all those
default devices.
ETEXI
SRST
``-nodefaults``
    Don't create default devices. Normally, QEMU sets the default
    devices like serial port, parallel port, virtual console, monitor
    device, VGA adapter, floppy and CD-ROM drive and others. The
    ``-nodefaults`` option will disable all those default devices.
ERST

#ifndef _WIN32
DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
    "-chroot dir     chroot to dir just before starting the VM\n",
    QEMU_ARCH_ALL)
#endif
STEXI
@item -chroot @var{dir}
@findex -chroot
Immediately before starting guest execution, chroot to the specified
directory.  Especially useful in combination with -runas.
ETEXI
SRST
``-chroot dir``
    Immediately before starting guest execution, chroot to the specified
    directory. Especially useful in combination with -runas.
ERST

#ifndef _WIN32
DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
    "-runas user     change to user id user just before starting the VM\n" \
    "                user can be numeric uid:gid instead\n",
    QEMU_ARCH_ALL)
#endif
STEXI
@item -runas @var{user}
@findex -runas
Immediately before starting guest execution, drop root privileges, switching
to the specified user.
ETEXI
SRST
``-runas user``
    Immediately before starting guest execution, drop root privileges,
    switching to the specified user.
ERST

DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
    "-prom-env variable=value\n"
    "                set OpenBIOS nvram variables\n",
    QEMU_ARCH_PPC | QEMU_ARCH_SPARC)
STEXI
@item -prom-env @var{variable}=@var{value}
@findex -prom-env
Set OpenBIOS nvram @var{variable} to given @var{value} (PPC, SPARC only).

@example
qemu-system-sparc -prom-env 'auto-boot?=false' \
 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
@end example

@example
qemu-system-ppc -prom-env 'auto-boot?=false' \
 -prom-env 'boot-device=hd:2,\yaboot' \
 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
@end example

ETEXI
SRST
``-prom-env variable=value``
    Set OpenBIOS nvram variable to given value (PPC, SPARC only).

    ::

        qemu-system-sparc -prom-env 'auto-boot?=false' \
         -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'

    ::

        qemu-system-ppc -prom-env 'auto-boot?=false' \
         -prom-env 'boot-device=hd:2,\yaboot' \
         -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
ERST
DEF("semihosting", 0, QEMU_OPTION_semihosting,
    "-semihosting    semihosting mode\n",
    QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
    QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
STEXI
@item -semihosting
@findex -semihosting
Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only).

Note that this allows guest direct access to the host filesystem, so
should only be used with a trusted guest OS.

See the -semihosting-config option documentation for further information
about the facilities this enables.
ETEXI
SRST
``-semihosting``
    Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only).

    Note that this allows guest direct access to the host filesystem, so
    should only be used with a trusted guest OS.

    See the -semihosting-config option documentation for further
    information about the facilities this enables.
ERST
DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
    "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
    "                semihosting configuration\n",
QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
STEXI
@item -semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]
@findex -semihosting-config
Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II only).

Note that this allows guest direct access to the host filesystem, so
should only be used with a trusted guest OS.

On Arm this implements the standard semihosting API, version 2.0.

On M68K this implements the "ColdFire GDB" interface used by libgloss.

Xtensa semihosting provides basic file IO calls, such as
open/read/write/seek/select. Tensilica baremetal libc for ISS and
linux platform "sim" use this interface.

@table @option
@item target=@code{native|gdb|auto}
Defines where the semihosting calls will be addressed, to QEMU (@code{native})
or to GDB (@code{gdb}). The default is @code{auto}, which means @code{gdb}
during debug sessions and @code{native} otherwise.
@item chardev=@var{str1}
Send the output to a chardev backend output for native or auto output when not in gdb
@item arg=@var{str1},arg=@var{str2},...
Allows the user to pass input arguments, and can be used multiple times to build
up a list. The old-style @code{-kernel}/@code{-append} method of passing a
command line is still supported for backward compatibility. If both the
@code{--semihosting-config arg} and the @code{-kernel}/@code{-append} are
specified, the former is passed to semihosting as it always takes precedence.
@end table
ETEXI
SRST
``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]``
    Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II
    only).

    Note that this allows guest direct access to the host filesystem, so
    should only be used with a trusted guest OS.

    On Arm this implements the standard semihosting API, version 2.0.

    On M68K this implements the "ColdFire GDB" interface used by
    libgloss.

    Xtensa semihosting provides basic file IO calls, such as
    open/read/write/seek/select. Tensilica baremetal libc for ISS and
    linux platform "sim" use this interface.

    ``target=native|gdb|auto``
        Defines where the semihosting calls will be addressed, to QEMU
        (``native``) or to GDB (``gdb``). The default is ``auto``, which
        means ``gdb`` during debug sessions and ``native`` otherwise.

    ``chardev=str1``
        Send the output to a chardev backend output for native or auto
        output when not in gdb

    ``arg=str1,arg=str2,...``
        Allows the user to pass input arguments, and can be used
        multiple times to build up a list. The old-style
        ``-kernel``/``-append`` method of passing a command line is
        still supported for backward compatibility. If both the
        ``--semihosting-config arg`` and the ``-kernel``/``-append`` are
        specified, the former is passed to semihosting as it always
        takes precedence.
ERST
DEF("old-param", 0, QEMU_OPTION_old_param,
    "-old-param      old param mode\n", QEMU_ARCH_ARM)
STEXI
@item -old-param
@findex -old-param (ARM)
Old param mode (ARM only).
ETEXI
SRST
``-old-param``
    Old param mode (ARM only).
ERST

DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
    "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
    "          [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
    "                Enable seccomp mode 2 system call filter (default 'off').\n" \
    "                use 'obsolete' to allow obsolete system calls that are provided\n" \
    "                    by the kernel, but typically no longer used by modern\n" \
    "                    C library implementations.\n" \
    "                use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
    "                    its privileges by blacklisting all set*uid|gid system calls.\n" \
    "                    The value 'children' will deny set*uid|gid system calls for\n" \
    "                    main QEMU process but will allow forks and execves to run unprivileged\n" \
    "                use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
    "                     blacklisting *fork and execve\n" \
    "                use 'resourcecontrol' to disable process affinity and schedular priority\n",
    QEMU_ARCH_ALL)
STEXI
@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}][,resourcecontrol=@var{string}]
@findex -sandbox
Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
disable it.  The default is 'off'.
@table @option
@item obsolete=@var{string}
Enable Obsolete system calls
@item elevateprivileges=@var{string}
Disable set*uid|gid system calls
@item spawn=@var{string}
Disable *fork and execve
@item resourcecontrol=@var{string}
Disable process affinity and schedular priority
@end table
ETEXI
SRST
``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]``
    Enable Seccomp mode 2 system call filter. 'on' will enable syscall
    filtering and 'off' will disable it. The default is 'off'.

    ``obsolete=string``
        Enable Obsolete system calls

    ``elevateprivileges=string``
        Disable set\*uid\|gid system calls

    ``spawn=string``
        Disable \*fork and execve

    ``resourcecontrol=string``
        Disable process affinity and schedular priority
ERST

DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
    "-readconfig <file>\n", QEMU_ARCH_ALL)
STEXI
@item -readconfig @var{file}
@findex -readconfig
Read device configuration from @var{file}. This approach is useful when you want to spawn
QEMU process with many command line options but you don't want to exceed the command line
character limit.
ETEXI
SRST
``-readconfig file``
    Read device configuration from file. This approach is useful when
    you want to spawn QEMU process with many command line options but
    you don't want to exceed the command line character limit.
ERST
DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
    "-writeconfig <file>\n"
    "                read/write config file\n", QEMU_ARCH_ALL)
STEXI
@item -writeconfig @var{file}
@findex -writeconfig
Write device configuration to @var{file}. The @var{file} can be either filename to save
command line and device configuration into file or dash @code{-}) character to print the
output to stdout. This can be later used as input file for @code{-readconfig} option.
ETEXI
SRST
``-writeconfig file``
    Write device configuration to file. The file can be either filename
    to save command line and device configuration into file or dash
    ``-``) character to print the output to stdout. This can be later
    used as input file for ``-readconfig`` option.
ERST

DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
    "-no-user-config\n"
    "                do not load default user-provided config files at startup\n",
    QEMU_ARCH_ALL)
STEXI
@item -no-user-config
@findex -no-user-config
The @code{-no-user-config} option makes QEMU not load any of the user-provided
config files on @var{sysconfdir}.
ETEXI
SRST
``-no-user-config``
    The ``-no-user-config`` option makes QEMU not load any of the
    user-provided config files on sysconfdir.
ERST

DEF("trace", HAS_ARG, QEMU_OPTION_trace,
    "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
    "                specify tracing options\n",
    QEMU_ARCH_ALL)
STEXI
HXCOMM This line is not accurate, as some sub-options are backend-specific but
HXCOMM HX does not support conditional compilation of text.
@item -trace [[enable=]@var{pattern}][,events=@var{file}][,file=@var{file}]
@findex -trace
@include docs/system/qemu-option-trace.texi
ETEXI
SRST
``-trace [[enable=]pattern][,events=file][,file=file]``
    Specify tracing options.

    ``[enable=]pattern``
        Immediately enable events matching pattern (either event name or
        a globbing pattern). This option is only available if QEMU has
        been compiled with the simple, log or ftrace tracing backend. To
        specify multiple events or patterns, specify the ``-trace``
        option multiple times.

        Use ``-trace help`` to print a list of names of trace points.

    ``events=file``
        Immediately enable events listed in file. The file must contain
        one event name (as listed in the ``trace-events-all`` file) per
        line; globbing patterns are accepted too. This option is only
        available if QEMU has been compiled with the simple, log or
        ftrace tracing backend.

    ``file=file``
        Log output traces to file. This option is only available if QEMU
        has been compiled with the simple tracing backend.
ERST
DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
    "-plugin [file=]<file>[,arg=<string>]\n"
    "                load a plugin\n",
    QEMU_ARCH_ALL)
STEXI
@item -plugin file=@var{file}[,arg=@var{string}]
@findex -plugin

Load a plugin.

@table @option
@item file=@var{file}
Load the given plugin from a shared library file.
@item arg=@var{string}
Argument string passed to the plugin. (Can be given multiple times.)
@end table
ETEXI
SRST
``-plugin file=file[,arg=string]``
    Load a plugin.

    ``file=file``
        Load the given plugin from a shared library file.

    ``arg=string``
        Argument string passed to the plugin. (Can be given multiple
        times.)
ERST

HXCOMM Internal use
DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)

#ifdef __linux__
DEF("enable-fips", 0, QEMU_OPTION_enablefips,
    "-enable-fips    enable FIPS 140-2 compliance\n",
    QEMU_ARCH_ALL)
#endif
STEXI
@item -enable-fips
@findex -enable-fips
Enable FIPS 140-2 compliance mode.
ETEXI
SRST
``-enable-fips``
    Enable FIPS 140-2 compliance mode.
ERST

HXCOMM Deprecated by -accel tcg
DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386)

DEF("msg", HAS_ARG, QEMU_OPTION_msg,
    "-msg timestamp[=on|off]\n"
    "                control error message format\n"
    "                timestamp=on enables timestamps (default: off)\n",
    QEMU_ARCH_ALL)
STEXI
@item -msg timestamp[=on|off]
@findex -msg
Control error message format.
@table @option
@item timestamp=on|off
Prefix messages with a timestamp.  Default is off.
@end table
ETEXI
SRST
``-msg timestamp[=on|off]``
    Control error message format.

    ``timestamp=on|off``
        Prefix messages with a timestamp. Default is off.
ERST

DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
    "-dump-vmstate <file>\n"
    "                Output vmstate information in JSON format to file.\n"
    "                Use the scripts/vmstate-static-checker.py file to\n"
    "                check for possible regressions in migration code\n"
    "                by comparing two such vmstate dumps.\n",
    QEMU_ARCH_ALL)
STEXI
@item -dump-vmstate @var{file}
@findex -dump-vmstate
Dump json-encoded vmstate information for current machine type to file
in @var{file}
ETEXI
SRST
``-dump-vmstate file``
    Dump json-encoded vmstate information for current machine type to
    file in file
ERST

DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
    "-enable-sync-profile\n"
    "                enable synchronization profiling\n",
    QEMU_ARCH_ALL)
STEXI
@item -enable-sync-profile
@findex -enable-sync-profile
Enable synchronization profiling.
ETEXI
SRST
``-enable-sync-profile``
    Enable synchronization profiling.
ERST

STEXI
@end table
ETEXI
DEFHEADING()

DEFHEADING(Generic object creation:)
STEXI
@table @option
ETEXI

DEF("object", HAS_ARG, QEMU_OPTION_object,
    "-object TYPENAME[,PROP1=VALUE1,...]\n"
    "                create a new object of type TYPENAME setting properties\n"
    "                in the order they are specified.  Note that the 'id'\n"
    "                property must be set.  These objects are placed in the\n"
    "                '/objects' path.\n",
    QEMU_ARCH_ALL)
STEXI
@item -object @var{typename}[,@var{prop1}=@var{value1},...]
@findex -object
Create a new object of type @var{typename} setting properties
in the order they are specified.  Note that the 'id'
property must be set.  These objects are placed in the
'/objects' path.

@table @option

@item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off},discard-data=@var{on|off},merge=@var{on|off},dump=@var{on|off},prealloc=@var{on|off},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},align=@var{align}

Creates a memory file backend object, which can be used to back
the guest RAM with huge pages.

The @option{id} parameter is a unique ID that will be used to reference this
memory region when configuring the @option{-numa} argument.

The @option{size} option provides the size of the memory region, and accepts
common suffixes, eg @option{500M}.

The @option{mem-path} provides the path to either a shared memory or huge page
filesystem mount.

The @option{share} boolean option determines whether the memory
region is marked as private to QEMU, or shared. The latter allows
a co-operating external process to access the QEMU memory region.

The @option{share} is also required for pvrdma devices due to
limitations in the RDMA API provided by Linux.

Setting share=on might affect the ability to configure NUMA
bindings for the memory backend under some circumstances, see
Documentation/vm/numa_memory_policy.txt on the Linux kernel
source tree for additional details.

Setting the @option{discard-data} boolean option to @var{on}
indicates that file contents can be destroyed when QEMU exits,
to avoid unnecessarily flushing data to the backing file.  Note
that @option{discard-data} is only an optimization, and QEMU
might not discard file contents if it aborts unexpectedly or is
terminated using SIGKILL.

The @option{merge} boolean option enables memory merge, also known as
MADV_MERGEABLE, so that Kernel Samepage Merging will consider the pages for
memory deduplication.

Setting the @option{dump} boolean option to @var{off} excludes the memory from
core dumps. This feature is also known as MADV_DONTDUMP.

The @option{prealloc} boolean option enables memory preallocation.

The @option{host-nodes} option binds the memory range to a list of NUMA host
nodes.

The @option{policy} option sets the NUMA policy to one of the following values:

@table @option
@item @var{default}
default host policy

@item @var{preferred}
prefer the given host node list for allocation

@item @var{bind}
restrict memory allocation to the given host node list

@item @var{interleave}
interleave memory allocations across the given host node list
@end table

The @option{align} option specifies the base address alignment when
QEMU mmap(2) @option{mem-path}, and accepts common suffixes, eg
@option{2M}. Some backend store specified by @option{mem-path}
requires an alignment different than the default one used by QEMU, eg
the device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
such cases, users can specify the required alignment via this option.

The @option{pmem} option specifies whether the backing file specified
by @option{mem-path} is in host persistent memory that can be accessed
using the SNIA NVM programming model (e.g. Intel NVDIMM).
If @option{pmem} is set to 'on', QEMU will take necessary operations to
guarantee the persistence of its own writes to @option{mem-path}
(e.g. in vNVDIMM label emulation and live migration).
Also, we will map the backend-file with MAP_SYNC flag, which ensures the
file metadata is in sync for @option{mem-path} in case of host crash
or a power failure. MAP_SYNC requires support from both the host kernel
(since Linux kernel 4.15) and the filesystem of @option{mem-path} mounted
with DAX option.

@item -object memory-backend-ram,id=@var{id},merge=@var{on|off},dump=@var{on|off},share=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave}

Creates a memory backend object, which can be used to back the guest RAM.
Memory backend objects offer more control than the @option{-m} option that is
traditionally used to define guest RAM. Please refer to
@option{memory-backend-file} for a description of the options.

@item -object memory-backend-memfd,id=@var{id},merge=@var{on|off},dump=@var{on|off},share=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},seal=@var{on|off},hugetlb=@var{on|off},hugetlbsize=@var{size}

Creates an anonymous memory file backend object, which allows QEMU to
share the memory with an external process (e.g. when using
vhost-user). The memory is allocated with memfd and optional
sealing. (Linux only)

The @option{seal} option creates a sealed-file, that will block
further resizing the memory ('on' by default).

The @option{hugetlb} option specify the file to be created resides in
the hugetlbfs filesystem (since Linux 4.14).  Used in conjunction with
the @option{hugetlb} option, the @option{hugetlbsize} option specify
the hugetlb page size on systems that support multiple hugetlb page
sizes (it must be a power of 2 value supported by the system).

In some versions of Linux, the @option{hugetlb} option is incompatible
with the @option{seal} option (requires at least Linux 4.16).

Please refer to @option{memory-backend-file} for a description of the
other options.

The @option{share} boolean option is @var{on} by default with memfd.

@item -object rng-builtin,id=@var{id}

Creates a random number generator backend which obtains entropy from
QEMU builtin functions. The @option{id} parameter is a unique ID that
will be used to reference this entropy backend from the @option{virtio-rng}
device. By default, the @option{virtio-rng} device uses this RNG backend.

@item -object rng-random,id=@var{id},filename=@var{/dev/random}

Creates a random number generator backend which obtains entropy from
a device on the host. The @option{id} parameter is a unique ID that
will be used to reference this entropy backend from the @option{virtio-rng}
device. The @option{filename} parameter specifies which file to obtain
entropy from and if omitted defaults to @option{/dev/urandom}.

@item -object rng-egd,id=@var{id},chardev=@var{chardevid}

Creates a random number generator backend which obtains entropy from
an external daemon running on the host. The @option{id} parameter is
a unique ID that will be used to reference this entropy backend from
the @option{virtio-rng} device. The @option{chardev} parameter is
the unique ID of a character device backend that provides the connection
to the RNG daemon.

@item -object tls-creds-anon,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/cred/dir},verify-peer=@var{on|off}

Creates a TLS anonymous credentials object, which can be used to provide
TLS support on network backends. The @option{id} parameter is a unique
ID which network backends will use to access the credentials. The
@option{endpoint} is either @option{server} or @option{client} depending
on whether the QEMU network backend that uses the credentials will be
acting as a client or as a server. If @option{verify-peer} is enabled
(the default) then once the handshake is completed, the peer credentials
will be verified, though this is a no-op for anonymous credentials.

The @var{dir} parameter tells QEMU where to find the credential
files. For server endpoints, this directory may contain a file
@var{dh-params.pem} providing diffie-hellman parameters to use
for the TLS server. If the file is missing, QEMU will generate
a set of DH parameters at startup. This is a computationally
expensive operation that consumes random pool entropy, so it is
recommended that a persistent set of parameters be generated
upfront and saved.

@item -object tls-creds-psk,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/keys/dir}[,username=@var{username}]

Creates a TLS Pre-Shared Keys (PSK) credentials object, which can be used to provide
TLS support on network backends. The @option{id} parameter is a unique
ID which network backends will use to access the credentials. The
@option{endpoint} is either @option{server} or @option{client} depending
on whether the QEMU network backend that uses the credentials will be
acting as a client or as a server. For clients only, @option{username}
is the username which will be sent to the server.  If omitted
it defaults to ``qemu''.

The @var{dir} parameter tells QEMU where to find the keys file.
It is called ``@var{dir}/keys.psk'' and contains ``username:key''
pairs.  This file can most easily be created using the GnuTLS
@code{psktool} program.

For server endpoints, @var{dir} may also contain a file
@var{dh-params.pem} providing diffie-hellman parameters to use
for the TLS server. If the file is missing, QEMU will generate
a set of DH parameters at startup. This is a computationally
expensive operation that consumes random pool entropy, so it is
recommended that a persistent set of parameters be generated
up front and saved.

@item -object tls-creds-x509,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/cred/dir},priority=@var{priority},verify-peer=@var{on|off},passwordid=@var{id}

Creates a TLS anonymous credentials object, which can be used to provide
TLS support on network backends. The @option{id} parameter is a unique
ID which network backends will use to access the credentials. The
@option{endpoint} is either @option{server} or @option{client} depending
on whether the QEMU network backend that uses the credentials will be
acting as a client or as a server. If @option{verify-peer} is enabled
(the default) then once the handshake is completed, the peer credentials
will be verified. With x509 certificates, this implies that the clients
must be provided with valid client certificates too.

The @var{dir} parameter tells QEMU where to find the credential
files. For server endpoints, this directory may contain a file
@var{dh-params.pem} providing diffie-hellman parameters to use
for the TLS server. If the file is missing, QEMU will generate
a set of DH parameters at startup. This is a computationally
expensive operation that consumes random pool entropy, so it is
recommended that a persistent set of parameters be generated
upfront and saved.

For x509 certificate credentials the directory will contain further files
providing the x509 certificates. The certificates must be stored
in PEM format, in filenames @var{ca-cert.pem}, @var{ca-crl.pem} (optional),
@var{server-cert.pem} (only servers), @var{server-key.pem} (only servers),
@var{client-cert.pem} (only clients), and @var{client-key.pem} (only clients).

For the @var{server-key.pem} and @var{client-key.pem} files which
contain sensitive private keys, it is possible to use an encrypted
version by providing the @var{passwordid} parameter. This provides
the ID of a previously created @code{secret} object containing the
password for decryption.

The @var{priority} parameter allows to override the global default
priority used by gnutls. This can be useful if the system administrator
needs to use a weaker set of crypto priorities for QEMU without
potentially forcing the weakness onto all applications. Or conversely
if one wants wants a stronger default for QEMU than for all other
applications, they can do this through this parameter. Its format is
a gnutls priority string as described at
@url{https://gnutls.org/manual/html_node/Priority-Strings.html}.

@item -object filter-buffer,id=@var{id},netdev=@var{netdevid},interval=@var{t}[,queue=@var{all|rx|tx}][,status=@var{on|off}][,position=@var{head|tail|id=<id>}][,insert=@var{behind|before}]

Interval @var{t} can't be 0, this filter batches the packet delivery: all
packets arriving in a given interval on netdev @var{netdevid} are delayed
until the end of the interval. Interval is in microseconds.
@option{status} is optional that indicate whether the netfilter is
on (enabled) or off (disabled), the default status for netfilter will be 'on'.

queue @var{all|rx|tx} is an option that can be applied to any netfilter.

@option{all}: the filter is attached both to the receive and the transmit
              queue of the netdev (default).

@option{rx}: the filter is attached to the receive queue of the netdev,
             where it will receive packets sent to the netdev.

@option{tx}: the filter is attached to the transmit queue of the netdev,
             where it will receive packets sent by the netdev.

position @var{head|tail|id=<id>} is an option to specify where the
filter should be inserted in the filter list. It can be applied to any
netfilter.

@option{head}: the filter is inserted at the head of the filter
               list, before any existing filters.

@option{tail}: the filter is inserted at the tail of the filter
               list, behind any existing filters (default).

@option{id=<id>}: the filter is inserted before or behind the filter
                  specified by <id>, see the insert option below.

insert @var{behind|before} is an option to specify where to insert the
new filter relative to the one specified with position=id=<id>. It can
be applied to any netfilter.

@option{before}: insert before the specified filter.

@option{behind}: insert behind the specified filter (default).

@item -object filter-mirror,id=@var{id},netdev=@var{netdevid},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support][,position=@var{head|tail|id=<id>}][,insert=@var{behind|before}]

filter-mirror on netdev @var{netdevid},mirror net packet to chardev@var{chardevid}, if it has the vnet_hdr_support flag, filter-mirror will mirror packet with vnet_hdr_len.

@item -object filter-redirector,id=@var{id},netdev=@var{netdevid},indev=@var{chardevid},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support][,position=@var{head|tail|id=<id>}][,insert=@var{behind|before}]

filter-redirector on netdev @var{netdevid},redirect filter's net packet to chardev
@var{chardevid},and redirect indev's packet to filter.if it has the vnet_hdr_support flag,
filter-redirector will redirect packet with vnet_hdr_len.
Create a filter-redirector we need to differ outdev id from indev id, id can not
be the same. we can just use indev or outdev, but at least one of indev or outdev
need to be specified.

@item -object filter-rewriter,id=@var{id},netdev=@var{netdevid},queue=@var{all|rx|tx},[vnet_hdr_support][,position=@var{head|tail|id=<id>}][,insert=@var{behind|before}]

Filter-rewriter is a part of COLO project.It will rewrite tcp packet to
secondary from primary to keep secondary tcp connection,and rewrite
tcp packet to primary from secondary make tcp packet can be handled by
client.if it has the vnet_hdr_support flag, we can parse packet with vnet header.

usage:
colo secondary:
-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
-object filter-rewriter,id=rew0,netdev=hn0,queue=all

@item -object filter-dump,id=@var{id},netdev=@var{dev}[,file=@var{filename}][,maxlen=@var{len}][,position=@var{head|tail|id=<id>}][,insert=@var{behind|before}]

Dump the network traffic on netdev @var{dev} to the file specified by
@var{filename}. At most @var{len} bytes (64k by default) per packet are stored.
The file format is libpcap, so it can be analyzed with tools such as tcpdump
or Wireshark.

@item -object colo-compare,id=@var{id},primary_in=@var{chardevid},secondary_in=@var{chardevid},outdev=@var{chardevid},iothread=@var{id}[,vnet_hdr_support][,notify_dev=@var{id}]

Colo-compare gets packet from primary_in@var{chardevid} and secondary_in@var{chardevid}, than compare primary packet with
secondary packet. If the packets are same, we will output primary
packet to outdev@var{chardevid}, else we will notify colo-frame
do checkpoint and send primary packet to outdev@var{chardevid}.
In order to improve efficiency, we need to put the task of comparison
in another thread. If it has the vnet_hdr_support flag, colo compare
will send/recv packet with vnet_hdr_len.
If you want to use Xen COLO, will need the notify_dev to notify Xen
colo-frame to do checkpoint.

we must use it with the help of filter-mirror and filter-redirector.

@example

KVM COLO

primary:
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
-device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
-chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
-chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
-chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
-chardev socket,id=compare0-0,host=3.3.3.3,port=9001
-chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
-chardev socket,id=compare_out0,host=3.3.3.3,port=9005
-object iothread,id=iothread1
-object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
-object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
-object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
-object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1

secondary:
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
-device e1000,netdev=hn0,mac=52:a4:00:12:78:66
-chardev socket,id=red0,host=3.3.3.3,port=9003
-chardev socket,id=red1,host=3.3.3.3,port=9004
-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1


Xen COLO

primary:
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
-device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
-chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
-chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
-chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
-chardev socket,id=compare0-0,host=3.3.3.3,port=9001
-chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
-chardev socket,id=compare_out0,host=3.3.3.3,port=9005
-chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait
-object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
-object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
-object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
-object iothread,id=iothread1
-object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1

secondary:
-netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
-device e1000,netdev=hn0,mac=52:a4:00:12:78:66
-chardev socket,id=red0,host=3.3.3.3,port=9003
-chardev socket,id=red1,host=3.3.3.3,port=9004
-object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
-object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1

@end example

If you want to know the detail of above command line, you can read
the colo-compare git log.

@item -object cryptodev-backend-builtin,id=@var{id}[,queues=@var{queues}]

Creates a cryptodev backend which executes crypto opreation from
the QEMU cipher APIS. The @var{id} parameter is
a unique ID that will be used to reference this cryptodev backend from
the @option{virtio-crypto} device. The @var{queues} parameter is optional,
which specify the queue number of cryptodev backend, the default of
@var{queues} is 1.

@example

 # @value{qemu_system} \
   [...] \
       -object cryptodev-backend-builtin,id=cryptodev0 \
       -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
   [...]
@end example

@item -object cryptodev-vhost-user,id=@var{id},chardev=@var{chardevid}[,queues=@var{queues}]

Creates a vhost-user cryptodev backend, backed by a chardev @var{chardevid}.
The @var{id} parameter is a unique ID that will be used to reference this
cryptodev backend from the @option{virtio-crypto} device.
The chardev should be a unix domain socket backed one. The vhost-user uses
a specifically defined protocol to pass vhost ioctl replacement messages
to an application on the other end of the socket.
The @var{queues} parameter is optional, which specify the queue number
of cryptodev backend for multiqueue vhost-user, the default of @var{queues} is 1.

@example

 # @value{qemu_system} \
   [...] \
       -chardev socket,id=chardev0,path=/path/to/socket \
       -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \
       -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
   [...]
@end example

@item -object secret,id=@var{id},data=@var{string},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]
@item -object secret,id=@var{id},file=@var{filename},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]

Defines a secret to store a password, encryption key, or some other sensitive
data. The sensitive data can either be passed directly via the @var{data}
parameter, or indirectly via the @var{file} parameter. Using the @var{data}
parameter is insecure unless the sensitive data is encrypted.

The sensitive data can be provided in raw format (the default), or base64.
When encoded as JSON, the raw format only supports valid UTF-8 characters,
so base64 is recommended for sending binary data. QEMU will convert from
which ever format is provided to the format it needs internally. eg, an
RBD password can be provided in raw format, even though it will be base64
encoded when passed onto the RBD sever.

For added protection, it is possible to encrypt the data associated with
a secret using the AES-256-CBC cipher. Use of encryption is indicated
by providing the @var{keyid} and @var{iv} parameters. The @var{keyid}
parameter provides the ID of a previously defined secret that contains
the AES-256 decryption key. This key should be 32-bytes long and be
base64 encoded. The @var{iv} parameter provides the random initialization
vector used for encryption of this particular secret and should be a
base64 encrypted string of the 16-byte IV.

The simplest (insecure) usage is to provide the secret inline

@example

 # @value{qemu_system} -object secret,id=sec0,data=letmein,format=raw

@end example

The simplest secure usage is to provide the secret via a file

 # printf "letmein" > mypasswd.txt
 # @value{qemu_system} -object secret,id=sec0,file=mypasswd.txt,format=raw

For greater security, AES-256-CBC should be used. To illustrate usage,
consider the openssl command line tool which can encrypt the data. Note
that when encrypting, the plaintext must be padded to the cipher block
size (32 bytes) using the standard PKCS#5/6 compatible padding algorithm.

First a master key needs to be created in base64 encoding:

@example
 # openssl rand -base64 32 > key.b64
 # KEY=$(base64 -d key.b64 | hexdump  -v -e '/1 "%02X"')
@end example

Each secret to be encrypted needs to have a random initialization vector
generated. These do not need to be kept secret

@example
 # openssl rand -base64 16 > iv.b64
 # IV=$(base64 -d iv.b64 | hexdump  -v -e '/1 "%02X"')
@end example

The secret to be defined can now be encrypted, in this case we're
telling openssl to base64 encode the result, but it could be left
as raw bytes if desired.

@example
 # SECRET=$(printf "letmein" |
            openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
@end example

When launching QEMU, create a master secret pointing to @code{key.b64}
and specify that to be used to decrypt the user password. Pass the
contents of @code{iv.b64} to the second secret

@example
 # @value{qemu_system} \
     -object secret,id=secmaster0,format=base64,file=key.b64 \
     -object secret,id=sec0,keyid=secmaster0,format=base64,\
         data=$SECRET,iv=$(<iv.b64)
@end example

@item -object sev-guest,id=@var{id},cbitpos=@var{cbitpos},reduced-phys-bits=@var{val},[sev-device=@var{string},policy=@var{policy},handle=@var{handle},dh-cert-file=@var{file},session-file=@var{file}]

Create a Secure Encrypted Virtualization (SEV) guest object, which can be used
to provide the guest memory encryption support on AMD processors.

When memory encryption is enabled, one of the physical address bit (aka the
C-bit) is utilized to mark if a memory page is protected. The @option{cbitpos}
is used to provide the C-bit position. The C-bit position is Host family dependent
hence user must provide this value. On EPYC, the value should be 47.

When memory encryption is enabled, we loose certain bits in physical address space.
The @option{reduced-phys-bits} is used to provide the number of bits we loose in
physical address space. Similar to C-bit, the value is Host family dependent.
On EPYC, the value should be 5.

The @option{sev-device} provides the device file to use for communicating with
the SEV firmware running inside AMD Secure Processor. The default device is
'/dev/sev'. If hardware supports memory encryption then /dev/sev devices are
created by CCP driver.

The @option{policy} provides the guest policy to be enforced by the SEV firmware
and restrict what configuration and operational commands can be performed on this
guest by the hypervisor. The policy should be provided by the guest owner and is
bound to the guest and cannot be changed throughout the lifetime of the guest.
The default is 0.

If guest @option{policy} allows sharing the key with another SEV guest then
@option{handle} can be use to provide handle of the guest from which to share
the key.

The @option{dh-cert-file} and @option{session-file} provides the guest owner's
Public Diffie-Hillman key defined in SEV spec. The PDH and session parameters
are used for establishing a cryptographic session with the guest owner to
negotiate keys used for attestation. The file must be encoded in base64.

e.g to launch a SEV guest
@example
 # @value{qemu_system_x86} \
     ......
     -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \
     -machine ...,memory-encryption=sev0
     .....

@end example


@item -object authz-simple,id=@var{id},identity=@var{string}

Create an authorization object that will control access to network services.

The @option{identity} parameter is identifies the user and its format
depends on the network service that authorization object is associated
with. For authorizing based on TLS x509 certificates, the identity must
be the x509 distinguished name. Note that care must be taken to escape
any commas in the distinguished name.

An example authorization object to validate a x509 distinguished name
would look like:
@example
 # @value{qemu_system} \
     ...
     -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \
     ...
@end example

Note the use of quotes due to the x509 distinguished name containing
whitespace, and escaping of ','.

@item -object authz-listfile,id=@var{id},filename=@var{path},refresh=@var{yes|no}

Create an authorization object that will control access to network services.

The @option{filename} parameter is the fully qualified path to a file
containing the access control list rules in JSON format.

An example set of rules that match against SASL usernames might look
like:

@example
  @{
    "rules": [
       @{ "match": "fred", "policy": "allow", "format": "exact" @},
       @{ "match": "bob", "policy": "allow", "format": "exact" @},
       @{ "match": "danb", "policy": "deny", "format": "glob" @},
       @{ "match": "dan*", "policy": "allow", "format": "exact" @},
    ],
    "policy": "deny"
  @}
@end example

When checking access the object will iterate over all the rules and
the first rule to match will have its @option{policy} value returned
as the result. If no rules match, then the default @option{policy}
value is returned.

The rules can either be an exact string match, or they can use the
simple UNIX glob pattern matching to allow wildcards to be used.

If @option{refresh} is set to true the file will be monitored
and automatically reloaded whenever its content changes.

As with the @code{authz-simple} object, the format of the identity
strings being matched depends on the network service, but is usually
a TLS x509 distinguished name, or a SASL username.

An example authorization object to validate a SASL username
would look like:
@example
 # @value{qemu_system} \
     ...
     -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=yes
     ...
@end example

@item -object authz-pam,id=@var{id},service=@var{string}

Create an authorization object that will control access to network services.

The @option{service} parameter provides the name of a PAM service to use
for authorization. It requires that a file @code{/etc/pam.d/@var{service}}
exist to provide the configuration for the @code{account} subsystem.

An example authorization object to validate a TLS x509 distinguished
name would look like:

@example
 # @value{qemu_system} \
     ...
     -object authz-pam,id=auth0,service=qemu-vnc
     ...
@end example

There would then be a corresponding config file for PAM at
@code{/etc/pam.d/qemu-vnc} that contains:

@example
account requisite  pam_listfile.so item=user sense=allow \
           file=/etc/qemu/vnc.allow
@end example

Finally the @code{/etc/qemu/vnc.allow} file would contain
the list of x509 distingished names that are permitted
access

@example
CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
@end example

@item -object iothread,id=@var{id},poll-max-ns=@var{poll-max-ns},poll-grow=@var{poll-grow},poll-shrink=@var{poll-shrink}

Creates a dedicated event loop thread that devices can be assigned to.  This is
known as an IOThread.  By default device emulation happens in vCPU threads or
the main event loop thread.  This can become a scalability bottleneck.
IOThreads allow device emulation and I/O to run on other host CPUs.

The @option{id} parameter is a unique ID that will be used to reference this
IOThread from @option{-device ...,iothread=@var{id}}.  Multiple devices can be
assigned to an IOThread.  Note that not all devices support an
@option{iothread} parameter.

The @code{query-iothreads} QMP command lists IOThreads and reports their thread
IDs so that the user can configure host CPU pinning/affinity.

IOThreads use an adaptive polling algorithm to reduce event loop latency.
Instead of entering a blocking system call to monitor file descriptors and then
pay the cost of being woken up when an event occurs, the polling algorithm
spins waiting for events for a short time.  The algorithm's default parameters
are suitable for many cases but can be adjusted based on knowledge of the
workload and/or host device latency.

The @option{poll-max-ns} parameter is the maximum number of nanoseconds to busy
wait for events.  Polling can be disabled by setting this value to 0.

The @option{poll-grow} parameter is the multiplier used to increase the polling
time when the algorithm detects it is missing events due to not polling long
enough.

The @option{poll-shrink} parameter is the divisor used to decrease the polling
time when the algorithm detects it is spending too long polling without
encountering events.

The polling parameters can be modified at run-time using the @code{qom-set} command (where @code{iothread1} is the IOThread's @code{id}):

@example
(qemu) qom-set /objects/iothread1 poll-max-ns 100000
@end example

@end table

ETEXI
SRST
``-object typename[,prop1=value1,...]``
    Create a new object of type typename setting properties in the order
    they are specified. Note that the 'id' property must be set. These
    objects are placed in the '/objects' path.

    ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align``
        Creates a memory file backend object, which can be used to back
        the guest RAM with huge pages.

        The ``id`` parameter is a unique ID that will be used to
        reference this memory region when configuring the ``-numa``
        argument.

        The ``size`` option provides the size of the memory region, and
        accepts common suffixes, eg ``500M``.

        The ``mem-path`` provides the path to either a shared memory or
        huge page filesystem mount.

        The ``share`` boolean option determines whether the memory
        region is marked as private to QEMU, or shared. The latter
        allows a co-operating external process to access the QEMU memory
        region.

        The ``share`` is also required for pvrdma devices due to
        limitations in the RDMA API provided by Linux.

        Setting share=on might affect the ability to configure NUMA
        bindings for the memory backend under some circumstances, see
        Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
        source tree for additional details.

        Setting the ``discard-data`` boolean option to on indicates that
        file contents can be destroyed when QEMU exits, to avoid
        unnecessarily flushing data to the backing file. Note that
        ``discard-data`` is only an optimization, and QEMU might not
        discard file contents if it aborts unexpectedly or is terminated
        using SIGKILL.

        The ``merge`` boolean option enables memory merge, also known as
        MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
        the pages for memory deduplication.

        Setting the ``dump`` boolean option to off excludes the memory
        from core dumps. This feature is also known as MADV\_DONTDUMP.

        The ``prealloc`` boolean option enables memory preallocation.

        The ``host-nodes`` option binds the memory range to a list of
        NUMA host nodes.

        The ``policy`` option sets the NUMA policy to one of the
        following values:

        ``default``
            default host policy

        ``preferred``
            prefer the given host node list for allocation

        ``bind``
            restrict memory allocation to the given host node list

        ``interleave``
            interleave memory allocations across the given host node
            list

        The ``align`` option specifies the base address alignment when
        QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
        ``2M``. Some backend store specified by ``mem-path`` requires an
        alignment different than the default one used by QEMU, eg the
        device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
        such cases, users can specify the required alignment via this
        option.

        The ``pmem`` option specifies whether the backing file specified
        by ``mem-path`` is in host persistent memory that can be
        accessed using the SNIA NVM programming model (e.g. Intel
        NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary
        operations to guarantee the persistence of its own writes to
        ``mem-path`` (e.g. in vNVDIMM label emulation and live
        migration). Also, we will map the backend-file with MAP\_SYNC
        flag, which ensures the file metadata is in sync for
        ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
        requires support from both the host kernel (since Linux kernel
        4.15) and the filesystem of ``mem-path`` mounted with DAX
        option.

    ``-object memory-backend-ram,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave``
        Creates a memory backend object, which can be used to back the
        guest RAM. Memory backend objects offer more control than the
        ``-m`` option that is traditionally used to define guest RAM.
        Please refer to ``memory-backend-file`` for a description of the
        options.

    ``-object memory-backend-memfd,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave,seal=on|off,hugetlb=on|off,hugetlbsize=size``
        Creates an anonymous memory file backend object, which allows
        QEMU to share the memory with an external process (e.g. when
        using vhost-user). The memory is allocated with memfd and
        optional sealing. (Linux only)

        The ``seal`` option creates a sealed-file, that will block
        further resizing the memory ('on' by default).

        The ``hugetlb`` option specify the file to be created resides in
        the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
        with the ``hugetlb`` option, the ``hugetlbsize`` option specify
        the hugetlb page size on systems that support multiple hugetlb
        page sizes (it must be a power of 2 value supported by the
        system).

        In some versions of Linux, the ``hugetlb`` option is
        incompatible with the ``seal`` option (requires at least Linux
        4.16).

        Please refer to ``memory-backend-file`` for a description of the
        other options.

        The ``share`` boolean option is on by default with memfd.

    ``-object rng-builtin,id=id``
        Creates a random number generator backend which obtains entropy
        from QEMU builtin functions. The ``id`` parameter is a unique ID
        that will be used to reference this entropy backend from the
        ``virtio-rng`` device. By default, the ``virtio-rng`` device
        uses this RNG backend.

    ``-object rng-random,id=id,filename=/dev/random``
        Creates a random number generator backend which obtains entropy
        from a device on the host. The ``id`` parameter is a unique ID
        that will be used to reference this entropy backend from the
        ``virtio-rng`` device. The ``filename`` parameter specifies
        which file to obtain entropy from and if omitted defaults to
        ``/dev/urandom``.

    ``-object rng-egd,id=id,chardev=chardevid``
        Creates a random number generator backend which obtains entropy
        from an external daemon running on the host. The ``id``
        parameter is a unique ID that will be used to reference this
        entropy backend from the ``virtio-rng`` device. The ``chardev``
        parameter is the unique ID of a character device backend that
        provides the connection to the RNG daemon.

    ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
        Creates a TLS anonymous credentials object, which can be used to
        provide TLS support on network backends. The ``id`` parameter is
        a unique ID which network backends will use to access the
        credentials. The ``endpoint`` is either ``server`` or ``client``
        depending on whether the QEMU network backend that uses the
        credentials will be acting as a client or as a server. If
        ``verify-peer`` is enabled (the default) then once the handshake
        is completed, the peer credentials will be verified, though this
        is a no-op for anonymous credentials.

        The dir parameter tells QEMU where to find the credential files.
        For server endpoints, this directory may contain a file
        dh-params.pem providing diffie-hellman parameters to use for the
        TLS server. If the file is missing, QEMU will generate a set of
        DH parameters at startup. This is a computationally expensive
        operation that consumes random pool entropy, so it is
        recommended that a persistent set of parameters be generated
        upfront and saved.

    ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
        Creates a TLS Pre-Shared Keys (PSK) credentials object, which
        can be used to provide TLS support on network backends. The
        ``id`` parameter is a unique ID which network backends will use
        to access the credentials. The ``endpoint`` is either ``server``
        or ``client`` depending on whether the QEMU network backend that
        uses the credentials will be acting as a client or as a server.
        For clients only, ``username`` is the username which will be
        sent to the server. If omitted it defaults to "qemu".

        The dir parameter tells QEMU where to find the keys file. It is
        called "dir/keys.psk" and contains "username:key" pairs. This
        file can most easily be created using the GnuTLS ``psktool``
        program.

        For server endpoints, dir may also contain a file dh-params.pem
        providing diffie-hellman parameters to use for the TLS server.
        If the file is missing, QEMU will generate a set of DH
        parameters at startup. This is a computationally expensive
        operation that consumes random pool entropy, so it is
        recommended that a persistent set of parameters be generated up
        front and saved.

    ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
        Creates a TLS anonymous credentials object, which can be used to
        provide TLS support on network backends. The ``id`` parameter is
        a unique ID which network backends will use to access the
        credentials. The ``endpoint`` is either ``server`` or ``client``
        depending on whether the QEMU network backend that uses the
        credentials will be acting as a client or as a server. If
        ``verify-peer`` is enabled (the default) then once the handshake
        is completed, the peer credentials will be verified. With x509
        certificates, this implies that the clients must be provided
        with valid client certificates too.

        The dir parameter tells QEMU where to find the credential files.
        For server endpoints, this directory may contain a file
        dh-params.pem providing diffie-hellman parameters to use for the
        TLS server. If the file is missing, QEMU will generate a set of
        DH parameters at startup. This is a computationally expensive
        operation that consumes random pool entropy, so it is
        recommended that a persistent set of parameters be generated
        upfront and saved.

        For x509 certificate credentials the directory will contain
        further files providing the x509 certificates. The certificates
        must be stored in PEM format, in filenames ca-cert.pem,
        ca-crl.pem (optional), server-cert.pem (only servers),
        server-key.pem (only servers), client-cert.pem (only clients),
        and client-key.pem (only clients).

        For the server-key.pem and client-key.pem files which contain
        sensitive private keys, it is possible to use an encrypted
        version by providing the passwordid parameter. This provides the
        ID of a previously created ``secret`` object containing the
        password for decryption.

        The priority parameter allows to override the global default
        priority used by gnutls. This can be useful if the system
        administrator needs to use a weaker set of crypto priorities for
        QEMU without potentially forcing the weakness onto all
        applications. Or conversely if one wants wants a stronger
        default for QEMU than for all other applications, they can do
        this through this parameter. Its format is a gnutls priority
        string as described at
        https://gnutls.org/manual/html_node/Priority-Strings.html.

    ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
        Interval t can't be 0, this filter batches the packet delivery:
        all packets arriving in a given interval on netdev netdevid are
        delayed until the end of the interval. Interval is in
        microseconds. ``status`` is optional that indicate whether the
        netfilter is on (enabled) or off (disabled), the default status
        for netfilter will be 'on'.

        queue all\|rx\|tx is an option that can be applied to any
        netfilter.

        ``all``: the filter is attached both to the receive and the
        transmit queue of the netdev (default).

        ``rx``: the filter is attached to the receive queue of the
        netdev, where it will receive packets sent to the netdev.

        ``tx``: the filter is attached to the transmit queue of the
        netdev, where it will receive packets sent by the netdev.

        position head\|tail\|id=<id> is an option to specify where the
        filter should be inserted in the filter list. It can be applied
        to any netfilter.

        ``head``: the filter is inserted at the head of the filter list,
        before any existing filters.

        ``tail``: the filter is inserted at the tail of the filter list,
        behind any existing filters (default).

        ``id=<id>``: the filter is inserted before or behind the filter
        specified by <id>, see the insert option below.

        insert behind\|before is an option to specify where to insert
        the new filter relative to the one specified with
        position=id=<id>. It can be applied to any netfilter.

        ``before``: insert before the specified filter.

        ``behind``: insert behind the specified filter (default).

    ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
        filter-mirror on netdev netdevid,mirror net packet to
        chardevchardevid, if it has the vnet\_hdr\_support flag,
        filter-mirror will mirror packet with vnet\_hdr\_len.

    ``-object filter-redirector,id=id,netdev=netdevid,indev=chardevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
        filter-redirector on netdev netdevid,redirect filter's net
        packet to chardev chardevid,and redirect indev's packet to
        filter.if it has the vnet\_hdr\_support flag, filter-redirector
        will redirect packet with vnet\_hdr\_len. Create a
        filter-redirector we need to differ outdev id from indev id, id
        can not be the same. we can just use indev or outdev, but at
        least one of indev or outdev need to be specified.

    ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
        Filter-rewriter is a part of COLO project.It will rewrite tcp
        packet to secondary from primary to keep secondary tcp
        connection,and rewrite tcp packet to primary from secondary make
        tcp packet can be handled by client.if it has the
        vnet\_hdr\_support flag, we can parse packet with vnet header.

        usage: colo secondary: -object
        filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object
        filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object
        filter-rewriter,id=rew0,netdev=hn0,queue=all

    ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]``
        Dump the network traffic on netdev dev to the file specified by
        filename. At most len bytes (64k by default) per packet are
        stored. The file format is libpcap, so it can be analyzed with
        tools such as tcpdump or Wireshark.

    ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id]``
        Colo-compare gets packet from primary\_inchardevid and
        secondary\_inchardevid, than compare primary packet with
        secondary packet. If the packets are same, we will output
        primary packet to outdevchardevid, else we will notify
        colo-frame do checkpoint and send primary packet to
        outdevchardevid. In order to improve efficiency, we need to put
        the task of comparison in another thread. If it has the
        vnet\_hdr\_support flag, colo compare will send/recv packet with
        vnet\_hdr\_len. If you want to use Xen COLO, will need the
        notify\_dev to notify Xen colo-frame to do checkpoint.

        we must use it with the help of filter-mirror and
        filter-redirector.

        ::

            KVM COLO

            primary:
            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
            -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
            -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
            -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
            -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
            -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
            -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
            -object iothread,id=iothread1
            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1

            secondary:
            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
            -chardev socket,id=red0,host=3.3.3.3,port=9003
            -chardev socket,id=red1,host=3.3.3.3,port=9004
            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1


            Xen COLO

            primary:
            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
            -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
            -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
            -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
            -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
            -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
            -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
            -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait
            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
            -object iothread,id=iothread1
            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1

            secondary:
            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
            -chardev socket,id=red0,host=3.3.3.3,port=9003
            -chardev socket,id=red1,host=3.3.3.3,port=9004
            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1

        If you want to know the detail of above command line, you can
        read the colo-compare git log.

    ``-object cryptodev-backend-builtin,id=id[,queues=queues]``
        Creates a cryptodev backend which executes crypto opreation from
        the QEMU cipher APIS. The id parameter is a unique ID that will
        be used to reference this cryptodev backend from the
        ``virtio-crypto`` device. The queues parameter is optional,
        which specify the queue number of cryptodev backend, the default
        of queues is 1.

        ::

             # |qemu_system| \
               [...] \
                   -object cryptodev-backend-builtin,id=cryptodev0 \
                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
               [...]

    ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]``
        Creates a vhost-user cryptodev backend, backed by a chardev
        chardevid. The id parameter is a unique ID that will be used to
        reference this cryptodev backend from the ``virtio-crypto``
        device. The chardev should be a unix domain socket backed one.
        The vhost-user uses a specifically defined protocol to pass
        vhost ioctl replacement messages to an application on the other
        end of the socket. The queues parameter is optional, which
        specify the queue number of cryptodev backend for multiqueue
        vhost-user, the default of queues is 1.

        ::

             # |qemu_system| \
               [...] \
                   -chardev socket,id=chardev0,path=/path/to/socket \
                   -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \
                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
               [...]

    ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]``
    ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]``
        Defines a secret to store a password, encryption key, or some
        other sensitive data. The sensitive data can either be passed
        directly via the data parameter, or indirectly via the file
        parameter. Using the data parameter is insecure unless the
        sensitive data is encrypted.

        The sensitive data can be provided in raw format (the default),
        or base64. When encoded as JSON, the raw format only supports
        valid UTF-8 characters, so base64 is recommended for sending
        binary data. QEMU will convert from which ever format is
        provided to the format it needs internally. eg, an RBD password
        can be provided in raw format, even though it will be base64
        encoded when passed onto the RBD sever.

        For added protection, it is possible to encrypt the data
        associated with a secret using the AES-256-CBC cipher. Use of
        encryption is indicated by providing the keyid and iv
        parameters. The keyid parameter provides the ID of a previously
        defined secret that contains the AES-256 decryption key. This
        key should be 32-bytes long and be base64 encoded. The iv
        parameter provides the random initialization vector used for
        encryption of this particular secret and should be a base64
        encrypted string of the 16-byte IV.

        The simplest (insecure) usage is to provide the secret inline

        ::

             # |qemu_system| -object secret,id=sec0,data=letmein,format=raw

        The simplest secure usage is to provide the secret via a file

        # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object
        secret,id=sec0,file=mypasswd.txt,format=raw

        For greater security, AES-256-CBC should be used. To illustrate
        usage, consider the openssl command line tool which can encrypt
        the data. Note that when encrypting, the plaintext must be
        padded to the cipher block size (32 bytes) using the standard
        PKCS#5/6 compatible padding algorithm.

        First a master key needs to be created in base64 encoding:

        ::

             # openssl rand -base64 32 > key.b64
             # KEY=$(base64 -d key.b64 | hexdump  -v -e '/1 "%02X"')

        Each secret to be encrypted needs to have a random
        initialization vector generated. These do not need to be kept
        secret

        ::

             # openssl rand -base64 16 > iv.b64
             # IV=$(base64 -d iv.b64 | hexdump  -v -e '/1 "%02X"')

        The secret to be defined can now be encrypted, in this case
        we're telling openssl to base64 encode the result, but it could
        be left as raw bytes if desired.

        ::

             # SECRET=$(printf "letmein" |
                        openssl enc -aes-256-cbc -a -K $KEY -iv $IV)

        When launching QEMU, create a master secret pointing to
        ``key.b64`` and specify that to be used to decrypt the user
        password. Pass the contents of ``iv.b64`` to the second secret

        ::

             # |qemu_system| \
                 -object secret,id=secmaster0,format=base64,file=key.b64 \
                 -object secret,id=sec0,keyid=secmaster0,format=base64,\
                     data=$SECRET,iv=$(<iv.b64)

    ``-object sev-guest,id=id,cbitpos=cbitpos,reduced-phys-bits=val,[sev-device=string,policy=policy,handle=handle,dh-cert-file=file,session-file=file]``
        Create a Secure Encrypted Virtualization (SEV) guest object,
        which can be used to provide the guest memory encryption support
        on AMD processors.

        When memory encryption is enabled, one of the physical address
        bit (aka the C-bit) is utilized to mark if a memory page is
        protected. The ``cbitpos`` is used to provide the C-bit
        position. The C-bit position is Host family dependent hence user
        must provide this value. On EPYC, the value should be 47.

        When memory encryption is enabled, we loose certain bits in
        physical address space. The ``reduced-phys-bits`` is used to
        provide the number of bits we loose in physical address space.
        Similar to C-bit, the value is Host family dependent. On EPYC,
        the value should be 5.

        The ``sev-device`` provides the device file to use for
        communicating with the SEV firmware running inside AMD Secure
        Processor. The default device is '/dev/sev'. If hardware
        supports memory encryption then /dev/sev devices are created by
        CCP driver.

        The ``policy`` provides the guest policy to be enforced by the
        SEV firmware and restrict what configuration and operational
        commands can be performed on this guest by the hypervisor. The
        policy should be provided by the guest owner and is bound to the
        guest and cannot be changed throughout the lifetime of the
        guest. The default is 0.

        If guest ``policy`` allows sharing the key with another SEV
        guest then ``handle`` can be use to provide handle of the guest
        from which to share the key.

        The ``dh-cert-file`` and ``session-file`` provides the guest
        owner's Public Diffie-Hillman key defined in SEV spec. The PDH
        and session parameters are used for establishing a cryptographic
        session with the guest owner to negotiate keys used for
        attestation. The file must be encoded in base64.

        e.g to launch a SEV guest

        ::

             # |qemu_system_x86| \
                 ......
                 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \
                 -machine ...,memory-encryption=sev0
                 .....

    ``-object authz-simple,id=id,identity=string``
        Create an authorization object that will control access to
        network services.

        The ``identity`` parameter is identifies the user and its format
        depends on the network service that authorization object is
        associated with. For authorizing based on TLS x509 certificates,
        the identity must be the x509 distinguished name. Note that care
        must be taken to escape any commas in the distinguished name.

        An example authorization object to validate a x509 distinguished
        name would look like:

        ::

             # |qemu_system| \
                 ...
                 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \
                 ...

        Note the use of quotes due to the x509 distinguished name
        containing whitespace, and escaping of ','.

    ``-object authz-listfile,id=id,filename=path,refresh=yes|no``
        Create an authorization object that will control access to
        network services.

        The ``filename`` parameter is the fully qualified path to a file
        containing the access control list rules in JSON format.

        An example set of rules that match against SASL usernames might
        look like:

        ::

              {
                "rules": [
                   { "match": "fred", "policy": "allow", "format": "exact" },
                   { "match": "bob", "policy": "allow", "format": "exact" },
                   { "match": "danb", "policy": "deny", "format": "glob" },
                   { "match": "dan*", "policy": "allow", "format": "exact" },
                ],
                "policy": "deny"
              }

        When checking access the object will iterate over all the rules
        and the first rule to match will have its ``policy`` value
        returned as the result. If no rules match, then the default
        ``policy`` value is returned.

        The rules can either be an exact string match, or they can use
        the simple UNIX glob pattern matching to allow wildcards to be
        used.

        If ``refresh`` is set to true the file will be monitored and
        automatically reloaded whenever its content changes.

        As with the ``authz-simple`` object, the format of the identity
        strings being matched depends on the network service, but is
        usually a TLS x509 distinguished name, or a SASL username.

        An example authorization object to validate a SASL username
        would look like:

        ::

             # |qemu_system| \
                 ...
                 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=yes
                 ...

    ``-object authz-pam,id=id,service=string``
        Create an authorization object that will control access to
        network services.

        The ``service`` parameter provides the name of a PAM service to
        use for authorization. It requires that a file
        ``/etc/pam.d/service`` exist to provide the configuration for
        the ``account`` subsystem.

        An example authorization object to validate a TLS x509
        distinguished name would look like:

        ::

             # |qemu_system| \
                 ...
                 -object authz-pam,id=auth0,service=qemu-vnc
                 ...

        There would then be a corresponding config file for PAM at
        ``/etc/pam.d/qemu-vnc`` that contains:

        ::

            account requisite  pam_listfile.so item=user sense=allow \
                       file=/etc/qemu/vnc.allow

        Finally the ``/etc/qemu/vnc.allow`` file would contain the list
        of x509 distingished names that are permitted access

        ::

            CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB

    ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink``
        Creates a dedicated event loop thread that devices can be
        assigned to. This is known as an IOThread. By default device
        emulation happens in vCPU threads or the main event loop thread.
        This can become a scalability bottleneck. IOThreads allow device
        emulation and I/O to run on other host CPUs.

        The ``id`` parameter is a unique ID that will be used to
        reference this IOThread from ``-device ...,iothread=id``.
        Multiple devices can be assigned to an IOThread. Note that not
        all devices support an ``iothread`` parameter.

        The ``query-iothreads`` QMP command lists IOThreads and reports
        their thread IDs so that the user can configure host CPU
        pinning/affinity.

        IOThreads use an adaptive polling algorithm to reduce event loop
        latency. Instead of entering a blocking system call to monitor
        file descriptors and then pay the cost of being woken up when an
        event occurs, the polling algorithm spins waiting for events for
        a short time. The algorithm's default parameters are suitable
        for many cases but can be adjusted based on knowledge of the
        workload and/or host device latency.

        The ``poll-max-ns`` parameter is the maximum number of
        nanoseconds to busy wait for events. Polling can be disabled by
        setting this value to 0.

        The ``poll-grow`` parameter is the multiplier used to increase
        the polling time when the algorithm detects it is missing events
        due to not polling long enough.

        The ``poll-shrink`` parameter is the divisor used to decrease
        the polling time when the algorithm detects it is spending too
        long polling without encountering events.

        The polling parameters can be modified at run-time using the
        ``qom-set`` command (where ``iothread1`` is the IOThread's
        ``id``):

        ::

            (qemu) qom-set /objects/iothread1 poll-max-ns 100000
ERST


HXCOMM This is the last statement. Insert new options before this line!
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@end table
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