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 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 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, tcg (default: tcg)\n" " kernel_irqchip=on|off controls accelerated irqchip support\n" " kernel_irqchip=on|off|split controls accelerated irqchip support (default=off)\n" " vmport=on|off|auto controls emulation of vmport (default: auto)\n" " kvm_shadow_mem=size of KVM shadow MMU\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" " iommu=on|off controls emulated Intel IOMMU (VT-d) support (default=off)\n" " igd-passthru=on|off controls IGD GFX passthrough support (default=off)\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", 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. 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, 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 kernel_irqchip=on|off Controls in-kernel irqchip support for the chosen accelerator when available. @item gfx_passthru=on|off Enables IGD GFX passthrough support for the chosen machine when available. @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 kvm_shadow_mem=size Defines the size of the KVM shadow MMU. @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 iommu=on|off Enables or disables emulated Intel IOMMU (VT-d) support. The default is off. @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. @end table ETEXI 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 DEF("smp", HAS_ARG, QEMU_OPTION_smp, "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,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\n" " threads= number of threads on one CPU core\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}][,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 socket, the number of @var{threads} per cores 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 DEF("numa", HAS_ARG, QEMU_OPTION_numa, "-numa node[,mem=size][,cpus=cpu[-cpu]][,nodeid=node]\n" "-numa node[,memdev=id][,cpus=cpu[-cpu]][,nodeid=node]\n", QEMU_ARCH_ALL) STEXI @item -numa node[,mem=@var{size}][,cpus=@var{cpu[-cpu]}][,nodeid=@var{node}] @itemx -numa node[,memdev=@var{id}][,cpus=@var{cpu[-cpu]}][,nodeid=@var{node}] @findex -numa Simulate a multi node NUMA system. If @samp{mem}, @samp{memdev} and @samp{cpus} are omitted, resources are split equally. Also, note that the -@option{numa} option doesn't allocate any of the specified resources. That is, 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, and possibly @option{-object} to specify the memory backend for the @samp{memdev} suboption. @samp{mem} and @samp{memdev} are mutually exclusive. Furthermore, if one node uses @samp{memdev}, all of them have to use it. ETEXI 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 qemu-system-i386 -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 DEF("set", HAS_ARG, QEMU_OPTION_set, "-set group.id.arg=value\n" " set parameter for item of type \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}\n" ETEXI 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 qemu-system-i386 -global ide-drive.physical_block_size=4096 -drive file=file,if=ide,index=0,media=disk @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 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}. 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 qemu-system-i386 -boot order=nc # boot from CD-ROM first, switch back to default order after reboot qemu-system-i386 -boot once=d # boot with a splash picture for 5 seconds. qemu-system-i386 -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 DEF("m", HAS_ARG, QEMU_OPTION_m, "-m[emory] [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 qemu-system-x86_64 -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 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 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 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 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 DEF("audio-help", 0, QEMU_OPTION_audio_help, "-audio-help print list of audio drivers and their options\n", QEMU_ARCH_ALL) STEXI @item -audio-help @findex -audio-help Will show the audio subsystem help: list of drivers, tunable parameters. ETEXI 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. @example qemu-system-i386 -soundhw sb16,adlib disk.img qemu-system-i386 -soundhw es1370 disk.img qemu-system-i386 -soundhw ac97 disk.img qemu-system-i386 -soundhw hda disk.img qemu-system-i386 -soundhw all disk.img qemu-system-i386 -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 DEF("balloon", HAS_ARG, QEMU_OPTION_balloon, "-balloon none disable balloon device\n" "-balloon virtio[,addr=str]\n" " enable virtio balloon device (default)\n", QEMU_ARCH_ALL) STEXI @item -balloon none @findex -balloon Disable balloon device. @item -balloon virtio[,addr=@var{addr}] Enable virtio balloon device (default), optionally with PCI address @var{addr}. ETEXI 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}] 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. @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 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 (on Linux)\n" " When debug-threads is enabled, individual threads are given a separate name (on Linux)\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 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 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 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 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 (@pxref{host_drives}). ETEXI DEF("drive", HAS_ARG, QEMU_OPTION_drive, "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" " [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n" " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" " [,serial=s][,addr=A][,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. Valid options are: @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. @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 cyls=@var{c},heads=@var{h},secs=@var{s}[,trans=@var{t}] These options have the same definition as they have in @option{-hdachs}. @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. @item aio=@var{aio} @var{aio} is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO. @item discard=@var{discard} @var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and controls whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap}) requests are ignored or passed to the filesystem. Some machine types may not support discard requests. @item format=@var{format} Specify which disk @var{format} will be used rather than detecting the format. Can be used to specifiy format=raw to avoid interpreting an untrusted format header. @item serial=@var{serial} This option specifies the serial number to assign to the device. @item addr=@var{addr} Specify the controller's PCI address (if=virtio only). @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 readonly Open drive @option{file} as read-only. Guest write attempts will fail. @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 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 UNMAP operation. @end table By default, the @option{cache=writeback} 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=writethrough}. 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. The host page cache can be avoided entirely with @option{cache=none}. This will attempt to do disk IO directly to the guest's memory. QEMU may still perform an internal copy of the data. Note that this is considered a writeback mode and the guest OS must handle the disk write cache correctly in order to avoid data corruption on host crashes. The host page cache can be avoided while only sending write notifications to the guest when the data has been flushed to the disk using @option{cache=directsync}. In case you don't care about data integrity over host failures, use @option{cache=unsafe}. 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. 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 qemu-system-i386 -drive file=file,index=2,media=cdrom @end example Instead of @option{-hda}, @option{-hdb}, @option{-hdc}, @option{-hdd}, you can use: @example qemu-system-i386 -drive file=file,index=0,media=disk qemu-system-i386 -drive file=file,index=1,media=disk qemu-system-i386 -drive file=file,index=2,media=disk qemu-system-i386 -drive file=file,index=3,media=disk @end example You can open an image using pre-opened file descriptors from an fd set: @example qemu-system-i386 -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 qemu-system-i386 -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 qemu-system-i386 -drive if=ide,index=1,media=cdrom @end example You can connect a SCSI disk with unit ID 6 on the bus #0: @example qemu-system-i386 -drive file=file,if=scsi,bus=0,unit=6 @end example Instead of @option{-fda}, @option{-fdb}, you can use: @example qemu-system-i386 -drive file=file,index=0,if=floppy qemu-system-i386 -drive file=file,index=1,if=floppy @end example By default, @var{interface} is "ide" and @var{index} is automatically incremented: @example qemu-system-i386 -drive file=a -drive file=b" @end example is interpreted like: @example qemu-system-i386 -hda a -hdb b @end example ETEXI 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 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 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 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 DEF("hdachs", HAS_ARG, QEMU_OPTION_hdachs, \ "-hdachs c,h,s[,t]\n" \ " force hard disk 0 physical geometry and the optional BIOS\n" \ " translation (t=none or lba) (usually QEMU can guess them)\n", QEMU_ARCH_ALL) STEXI @item -hdachs @var{c},@var{h},@var{s},[,@var{t}] @findex -hdachs Force hard disk 0 physical geometry (1 <= @var{c} <= 16383, 1 <= @var{h} <= 16, 1 <= @var{s} <= 63) and optionally force the BIOS translation mode (@var{t}=none, lba or auto). Usually QEMU can guess all those parameters. This option is useful for old MS-DOS disk images. ETEXI DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev, "-fsdev fsdriver,id=id[,path=path,][security_model={mapped-xattr|mapped-file|passthrough|none}]\n" " [,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd]\n", QEMU_ARCH_ALL) STEXI @item -fsdev @var{fsdriver},id=@var{id},path=@var{path},[security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}] @findex -fsdev Define a new file system device. Valid options are: @table @option @item @var{fsdriver} This option specifies the fs driver backend to use. Currently "local", "handle" and "proxy" file system drivers are supported. @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 handle, 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 @item sock_fd=@var{sock_fd} Enables proxy filesystem driver to use passed socket descriptor for communicating with virtfs-proxy-helper. Usually a helper like libvirt will create socketpair and pass one of the fds as sock_fd @end table -fsdev option is used along with -device driver "virtio-9p-pci". @item -device virtio-9p-pci,fsdev=@var{id},mount_tag=@var{mount_tag} Options for virtio-9p-pci driver are: @table @option @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 DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, "-virtfs local,path=path,mount_tag=tag,security_model=[mapped-xattr|mapped-file|passthrough|none]\n" " [,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd]\n", QEMU_ARCH_ALL) STEXI @item -virtfs @var{fsdriver}[,path=@var{path}],mount_tag=@var{mount_tag}[,security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}] @findex -virtfs The general form of a Virtual File system pass-through options are: @table @option @item @var{fsdriver} This option specifies the fs driver backend to use. Currently "local", "handle" and "proxy" file system drivers are supported. @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 handle, 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. 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 @end table ETEXI DEF("virtfs_synth", 0, QEMU_OPTION_virtfs_synth, "-virtfs_synth Create synthetic file system image\n", QEMU_ARCH_ALL) STEXI @item -virtfs_synth @findex -virtfs_synth Create synthetic file system image ETEXI STEXI @end table ETEXI DEFHEADING() DEFHEADING(USB options:) STEXI @table @option ETEXI DEF("usb", 0, QEMU_OPTION_usb, "-usb enable the USB driver (will be the default soon)\n", QEMU_ARCH_ALL) STEXI @item -usb @findex -usb Enable the USB driver (will be the default soon) ETEXI 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}. @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 disk:[format=@var{format}]:@var{file} Mass storage device based on file. The optional @var{format} argument will be used rather than detecting the format. Can be used to specifiy @code{format=raw} to avoid interpreting an untrusted format header. @item host:@var{bus}.@var{addr} Pass through the host device identified by @var{bus}.@var{addr} (Linux only). @item host:@var{vendor_id}:@var{product_id} Pass through the host device identified by @var{vendor_id}:@var{product_id} (Linux only). @item serial:[vendorid=@var{vendor_id}][,productid=@var{product_id}]:@var{dev} Serial converter to host character device @var{dev}, see @code{-serial} for the available devices. @item braille Braille device. This will use BrlAPI to display the braille output on a real or fake device. @item net:@var{options} Network adapter that supports CDC ethernet and RNDIS protocols. @end table ETEXI STEXI @end table ETEXI DEFHEADING() DEFHEADING(Display options:) STEXI @table @option ETEXI DEF("display", HAS_ARG, QEMU_OPTION_display, "-display sdl[,frame=on|off][,alt_grab=on|off][,ctrl_grab=on|off]\n" " [,window_close=on|off]|curses|none|\n" " gtk[,grab_on_hover=on|off]|\n" " vnc=[,]\n" " select display type\n", 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. 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. @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 @end table ETEXI 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, QEMU uses SDL to display the VGA output. 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 DEF("curses", 0, QEMU_OPTION_curses, "-curses use a curses/ncurses interface instead of SDL\n", QEMU_ARCH_ALL) STEXI @item -curses @findex -curses Normally, QEMU uses SDL to display the VGA output. 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 DEF("no-frame", 0, QEMU_OPTION_no_frame, "-no-frame open SDL window without a frame and window decorations\n", QEMU_ARCH_ALL) STEXI @item -no-frame @findex -no-frame Do not use decorations for SDL windows and start them using the whole available screen space. This makes the using QEMU in a dedicated desktop workspace more convenient. ETEXI 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 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 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 DEF("sdl", 0, QEMU_OPTION_sdl, "-sdl enable SDL\n", QEMU_ARCH_ALL) STEXI @item -sdl @findex -sdl Enable SDL. ETEXI DEF("spice", HAS_ARG, QEMU_OPTION_spice, "-spice [port=port][,tls-port=secured-port][,x509-dir=]\n" " [,x509-key-file=][,x509-key-password=]\n" " [,x509-cert-file=][,x509-cacert-file=]\n" " [,x509-dh-key-file=][,addr=addr][,ipv4|ipv6|unix]\n" " [,tls-ciphers=]\n" " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n" " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n" " [,sasl][,password=][,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]]\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= Set the TCP port spice is listening on for plaintext channels. @item 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= 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= Set the TCP port spice is listening on for encrypted channels. @item x509-dir= Set the x509 file directory. Expects same filenames as -vnc $display,x509=$dir @item x509-key-file= @itemx x509-key-password= @itemx x509-cert-file= @itemx x509-cacert-file= @itemx x509-dh-key-file= The x509 file names can also be configured individually. @item tls-ciphers= 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 filter. @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. @end table ETEXI 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 DEF("rotate", HAS_ARG, QEMU_OPTION_rotate, "-rotate 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 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 one is the default) @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. @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 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 DEF("g", 1, QEMU_OPTION_g , "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n", QEMU_ARCH_PPC | QEMU_ARCH_SPARC) STEXI @item -g @var{width}x@var{height}[x@var{depth}] @findex -g Set the initial graphical resolution and depth (PPC, SPARC only). ETEXI DEF("vnc", HAS_ARG, QEMU_OPTION_vnc , "-vnc display start a VNC server on display\n", QEMU_ARCH_ALL) STEXI @item -vnc @var{display}[,@var{option}[,@var{option}[,...]]] @findex -vnc Normally, QEMU uses SDL to display the VGA output. 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{-usbdevice 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 @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. By definition the Websocket port is 5700+@var{display}. If @var{host} is specified connections will only be allowed from this host. As an alternative the Websocket port could be specified by using @code{websocket}=@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 } where could be either "vnc" or "spice". If you would like to change password expiration, you should use @code{expire_password } 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 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. The @option{tls-creds} parameter obsoletes the @option{tls}, @option{x509}, and @option{x509verify} options, and as such it is not permitted to set both new and old type options at the same time. @item tls Require that client use TLS when communicating with the VNC server. This uses anonymous TLS credentials so is susceptible to a man-in-the-middle attack. It is recommended that this option be combined with either the @option{x509} or @option{x509verify} options. This option is now deprecated in favor of using the @option{tls-creds} argument. @item x509=@var{/path/to/certificate/dir} Valid if @option{tls} is specified. Require that x509 credentials are used for negotiating the TLS session. The server will send its x509 certificate to the client. It is recommended that a password be set on the VNC server to provide authentication of the client when this is used. The path following this option specifies where the x509 certificates are to be loaded from. See the @ref{vnc_security} section for details on generating certificates. This option is now deprecated in favour of using the @option{tls-creds} argument. @item x509verify=@var{/path/to/certificate/dir} Valid if @option{tls} is specified. Require that x509 credentials are used for negotiating the TLS session. The server will send its x509 certificate to the client, and request that the client send its own x509 certificate. The server will validate the client's certificate against the CA certificate, and reject clients when validation fails. If the certificate authority is trusted, this is a sufficient authentication mechanism. You may still wish to set a password on the VNC server as a second authentication layer. The path following this option specifies where the x509 certificates are to be loaded from. See the @ref{vnc_security} section for details on generating certificates. This option is now deprecated in favour of using the @option{tls-creds} argument. @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 acl Turn on access control lists for checking of the x509 client certificate and SASL party. For x509 certs, the ACL check is made against the certificate's distinguished name. This is something that looks like @code{C=GB,O=ACME,L=Boston,CN=bob}. For SASL party, the ACL check is made against the username, which depending on the SASL plugin, may include a realm component, eg @code{bob} or @code{bob@@EXAMPLE.COM}. When the @option{acl} flag is set, the initial access list will be empty, with a @code{deny} policy. Thus no one will be allowed to use the VNC server until the ACLs have been loaded. This can be achieved using the @code{acl} monitor command. @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 1. 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. @end table ETEXI 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 HXCOMM Deprecated by -rtc DEF("rtc-td-hack", 0, QEMU_OPTION_rtc_td_hack, "", QEMU_ARCH_I386) 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 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 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 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 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}][,family=@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 STEXI @end table ETEXI DEFHEADING() DEFHEADING(Network options:) STEXI @table @option ETEXI HXCOMM Legacy slirp options (now moved to -net user): #ifdef CONFIG_SLIRP DEF("tftp", HAS_ARG, QEMU_OPTION_tftp, "", QEMU_ARCH_ALL) DEF("bootp", HAS_ARG, QEMU_OPTION_bootp, "", QEMU_ARCH_ALL) DEF("redir", HAS_ARG, QEMU_OPTION_redir, "", QEMU_ARCH_ALL) #ifndef _WIN32 DEF("smb", HAS_ARG, QEMU_OPTION_smb, "", QEMU_ARCH_ALL) #endif #endif 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][,tftp=dir]\n" " [,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" " [,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" " configure a host TAP network backend with ID 'str'\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" "-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 (RFC3391). 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 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" " configure a vhost-user network, backed by a chardev 'dev'\n" "-netdev hubport,id=str,hubid=n\n" " configure a hub port on QEMU VLAN 'n'\n", QEMU_ARCH_ALL) DEF("net", HAS_ARG, QEMU_OPTION_net, "-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" " old way to create a new NIC and connect it to VLAN 'n'\n" " (use the '-device devtype,netdev=str' option if possible instead)\n" "-net dump[,vlan=n][,file=f][,len=n]\n" " dump traffic on vlan 'n' to file 'f' (max n bytes per packet)\n" "-net none use it alone to have zero network devices. If no -net option\n" " is provided, the default is '-net nic -net user'\n" "-net [" #ifdef CONFIG_SLIRP "user|" #endif "tap|" "bridge|" #ifdef CONFIG_VDE "vde|" #endif #ifdef CONFIG_NETMAP "netmap|" #endif "socket][,vlan=n][,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 -net nic[,vlan=@var{n}][,macaddr=@var{mac}][,model=@var{type}] [,name=@var{name}][,addr=@var{addr}][,vectors=@var{v}] @findex -net Create a new Network Interface Card and connect it to VLAN @var{n} (@var{n} = 0 is the default). The NIC is an e1000 by default on the PC target. 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. Valid values for @var{type} are @code{virtio}, @code{i82551}, @code{i82557b}, @code{i82559er}, @code{ne2k_pci}, @code{ne2k_isa}, @code{pcnet}, @code{rtl8139}, @code{e1000}, @code{smc91c111}, @code{lance} and @code{mcf_fec}. Not all devices are supported on all targets. Use @code{-net nic,model=help} for a list of available devices for your target. @item -netdev user,id=@var{id}[,@var{option}][,@var{option}][,...] @findex -netdev @item -net user[,@var{option}][,@var{option}][,...] Use the user mode network stack which requires no administrator privilege to run. Valid options are: @table @option @item vlan=@var{n} Connect user mode stack to VLAN @var{n} (@var{n} = 0 is the default). @item id=@var{id} @itemx name=@var{name} Assign symbolic name for use in monitor commands. @option{ipv4} and @option{ipv6} 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 qemu -net user,dnssearch=mgmt.example.org,dnssearch=example.org [...] @end example @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 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 qemu-system-i386 -hda linux.img -boot n -net user,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. QEMU was tested successfully with smbd versions from Red Hat 9, Fedora Core 3 and OpenSUSE 11.x. @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 qemu-system-i386 -net 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 qemu-system-i386 -net 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 qemu -net 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 qemu -net 'user,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321' @end example @end table Note: Legacy stand-alone options -tftp, -bootp, -smb and -redir are still processed and applied to -net user. Mixing them with the new configuration syntax gives undefined results. Their use for new applications is discouraged as they will be removed from future versions. @item -netdev tap,id=@var{id}[,fd=@var{h}][,ifname=@var{name}][,script=@var{file}][,downscript=@var{dfile}][,helper=@var{helper}] @itemx -net tap[,vlan=@var{n}][,name=@var{name}][,fd=@var{h}][,ifname=@var{name}][,script=@var{file}][,downscript=@var{dfile}][,helper=@var{helper}] Connect the host TAP network interface @var{name} to VLAN @var{n}. 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. The default network helper executable is @file{/path/to/qemu-bridge-helper}. @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 qemu-system-i386 linux.img -net nic -net tap @end example @example #launch a QEMU instance with two NICs, each one connected #to a TAP device qemu-system-i386 linux.img \ -net nic,vlan=0 -net tap,vlan=0,ifname=tap0 \ -net nic,vlan=1 -net tap,vlan=1,ifname=tap1 @end example @example #launch a QEMU instance with the default network helper to #connect a TAP device to bridge br0 qemu-system-i386 linux.img \ -net nic -net tap,"helper=/path/to/qemu-bridge-helper" @end example @item -netdev bridge,id=@var{id}[,br=@var{bridge}][,helper=@var{helper}] @itemx -net bridge[,vlan=@var{n}][,name=@var{name}][,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 qemu-system-i386 linux.img -net bridge -net nic,model=virtio @end example @example #launch a QEMU instance with the default network helper to #connect a TAP device to bridge qemubr0 qemu-system-i386 linux.img -net bridge,br=qemubr0 -net nic,model=virtio @end example @item -netdev socket,id=@var{id}[,fd=@var{h}][,listen=[@var{host}]:@var{port}][,connect=@var{host}:@var{port}] @itemx -net socket[,vlan=@var{n}][,name=@var{name}][,fd=@var{h}] [,listen=[@var{host}]:@var{port}][,connect=@var{host}:@var{port}] Connect the VLAN @var{n} to a remote VLAN in 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 qemu-system-i386 linux.img \ -net nic,macaddr=52:54:00:12:34:56 \ -net socket,listen=:1234 # connect the VLAN 0 of this instance to the VLAN 0 # of the first instance qemu-system-i386 linux.img \ -net nic,macaddr=52:54:00:12:34:57 \ -net socket,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}]] @itemx -net socket[,vlan=@var{n}][,name=@var{name}][,fd=@var{h}][,mcast=@var{maddr}:@var{port}[,localaddr=@var{addr}]] Create a VLAN @var{n} shared 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 qemu-system-i386 linux.img \ -net nic,macaddr=52:54:00:12:34:56 \ -net socket,mcast=230.0.0.1:1234 # launch another QEMU instance on same "bus" qemu-system-i386 linux.img \ -net nic,macaddr=52:54:00:12:34:57 \ -net socket,mcast=230.0.0.1:1234 # launch yet another QEMU instance on same "bus" qemu-system-i386 linux.img \ -net nic,macaddr=52:54:00:12:34:58 \ -net socket,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) qemu-system-i386 linux.img \ -net nic,macaddr=52:54:00:12:34:56 \ -net socket,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 qemu-system-i386 linux.img \ -net nic,macaddr=52:54:00:12:34:56 \ -net socket,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}] @itemx -net l2tpv3[,vlan=@var{n}][,name=@var{name}],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}] Connect VLAN @var{n} to L2TPv3 pseudowire. L2TPv3 (RFC3391) 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. @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 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 qemu-system-i386 linux.img -net nic -net l2tpv3,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}] @itemx -net vde[,vlan=@var{n}][,name=@var{name}][,sock=@var{socketpath}] [,port=@var{n}][,group=@var{groupname}][,mode=@var{octalmode}] Connect VLAN @var{n} 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 qemu-system-i386 linux.img -net nic -net vde,sock=/tmp/myswitch @end example @item -netdev hubport,id=@var{id},hubid=@var{hubid} Create a hub port on QEMU "vlan" @var{hubid}. The hubport netdev lets you connect a NIC to a QEMU "vlan" instead of a single netdev. @code{-net} and @code{-device} with parameter @option{vlan} create the required hub automatically. @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,path=/path/to/socket \ -netdev type=vhost-user,id=net0,chardev=chr0 \ -device virtio-net-pci,netdev=net0 @end example @item -net dump[,vlan=@var{n}][,file=@var{file}][,len=@var{len}] Dump network traffic on VLAN @var{n} to file @var{file} (@file{qemu-vlan0.pcap} by default). 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. Note: For devices created with '-netdev', use '-object filter-dump,...' instead. @item -net none Indicate that no network devices should be configured. It is used to override the default configuration (@option{-net nic -net user}) which is activated if no @option{-net} options are provided. ETEXI STEXI @end table ETEXI DEFHEADING() DEFHEADING(Character device options:) STEXI The general form of a character device option is: @table @option ETEXI DEF("chardev", HAS_ARG, QEMU_OPTION_chardev, "-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][,reconnect=seconds][,mux=on|off]\n" " [,logfile=PATH][,logappend=on|off][,tls-creds=ID] (tcp)\n" "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,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 @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. 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,default \ -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,default \ -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. Further options to each backend are described below. @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] [,reconnect=@var{seconds}] [,tls-creds=@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{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. 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. @option{stdio} is not available on Windows hosts. @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 STEXI @end table ETEXI DEFHEADING() DEFHEADING(Device URL Syntax:) STEXI In addition to using normal file images for the emulated storage devices, QEMU can also use networked resources such as iSCSI devices. These are specified using a special URL syntax. @table @option @item iSCSI iSCSI support allows QEMU to access iSCSI resources directly and use as images for the guest storage. Both disk and cdrom images are supported. Syntax for specifying iSCSI LUNs is ``iscsi://[:]//'' By default qemu will use the iSCSI initiator-name 'iqn.2008-11.org.linux-kvm[:]' but this can also be set from the command line or a configuration file. Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect stalled requests and force a reestablishment of the session. The timeout is specified in seconds. The default is 0 which means no timeout. Libiscsi 1.15.0 or greater is required for this feature. Example (without authentication): @example qemu-system-i386 -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \ -cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \ -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1 @end example Example (CHAP username/password via URL): @example qemu-system-i386 -drive file=iscsi://user%password@@192.0.2.1/iqn.2001-04.com.example/1 @end example Example (CHAP username/password via environment variables): @example LIBISCSI_CHAP_USERNAME="user" \ LIBISCSI_CHAP_PASSWORD="password" \ qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1 @end example iSCSI support is an optional feature of QEMU and only available when compiled and linked against libiscsi. ETEXI 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 iSCSI parameters such as username and password can also be specified via a configuration file. See qemu-doc for more information and examples. @item NBD QEMU supports NBD (Network Block Devices) both using TCP protocol as well as Unix Domain Sockets. Syntax for specifying a NBD device using TCP ``nbd::[:exportname=]'' Syntax for specifying a NBD device using Unix Domain Sockets ``nbd:unix:[:exportname=]'' Example for TCP @example qemu-system-i386 --drive file=nbd:192.0.2.1:30000 @end example Example for Unix Domain Sockets @example qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket @end example @item SSH QEMU supports SSH (Secure Shell) access to remote disks. Examples: @example qemu-system-i386 -drive file=ssh://user@@host/path/to/disk.img qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img @end example Currently authentication must be done using ssh-agent. Other authentication methods may be supported in future. @item Sheepdog Sheepdog is a distributed storage system for QEMU. QEMU supports using either local sheepdog devices or remote networked devices. Syntax for specifying a sheepdog device @example sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag] @end example Example @example qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine @end example See also @url{http://http://www.osrg.net/sheepdog/}. @item GlusterFS GlusterFS is an user space distributed file system. QEMU supports the use of GlusterFS volumes for hosting VM disk images using TCP, Unix Domain Sockets and RDMA transport protocols. Syntax for specifying a VM disk image on GlusterFS volume is @example gluster[+transport]://[server[:port]]/volname/image[?socket=...] @end example Example @example qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img @end example See also @url{http://www.gluster.org}. @item HTTP/HTTPS/FTP/FTPS/TFTP QEMU supports read-only access to files accessed over http(s), ftp(s) and tftp. Syntax using a single filename: @example ://[[:]@@]/ @end example where: @table @option @item protocol 'http', 'https', 'ftp', 'ftps', or 'tftp'. @item username Optional username for authentication to the remote server. @item password Optional password for authentication to the remote server. @item host Address of the remote server. @item path Path on the remote server, including any query string. @end table The following options are also supported: @table @option @item url The full URL when passing options to the driver explicitly. @item readahead The amount of data to read ahead with each range request to the remote server. This value may optionally have the suffix 'T', 'G', 'M', 'K', 'k' or 'b'. If it does not have a suffix, it will be assumed to be in bytes. The value must be a multiple of 512 bytes. It defaults to 256k. @item sslverify Whether to verify the remote server's certificate when connecting over SSL. It can have the value 'on' or 'off'. It defaults to 'on'. @item cookie Send this cookie (it can also be a list of cookies separated by ';') with each outgoing request. Only supported when using protocols such as HTTP which support cookies, otherwise ignored. @item timeout Set the timeout in seconds of the CURL connection. This timeout is the time that CURL waits for a response from the remote server to get the size of the image to be downloaded. If not set, the default timeout of 5 seconds is used. @end table Note that when passing options to qemu explicitly, @option{driver} is the value of . Example: boot from a remote Fedora 20 live ISO image @example qemu-system-x86_64 --drive media=cdrom,file=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly qemu-system-x86_64 --drive media=cdrom,file.driver=http,file.url=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly @end example Example: boot from a remote Fedora 20 cloud image using a local overlay for writes, copy-on-read, and a readahead of 64k @example qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"http",, "file.url":"https://dl.fedoraproject.org/pub/fedora/linux/releases/20/Images/x86_64/Fedora-x86_64-20-20131211.1-sda.qcow2",, "file.readahead":"64k"@}' /tmp/Fedora-x86_64-20-20131211.1-sda.qcow2 qemu-system-x86_64 -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on @end example Example: boot from an image stored on a VMware vSphere server with a self-signed certificate using a local overlay for writes, a readahead of 64k and a timeout of 10 seconds. @example qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"https",, "file.url":"https://user:password@@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k",, "file.timeout":10@}' /tmp/test.qcow2 qemu-system-x86_64 -drive file=/tmp/test.qcow2 @end example ETEXI STEXI @end table ETEXI DEFHEADING(Bluetooth(R) options:) STEXI @table @option ETEXI DEF("bt", HAS_ARG, QEMU_OPTION_bt, \ "-bt hci,null dumb bluetooth HCI - doesn't respond to commands\n" \ "-bt hci,host[:id]\n" \ " use host's HCI with the given name\n" \ "-bt hci[,vlan=n]\n" \ " emulate a standard HCI in virtual scatternet 'n'\n" \ "-bt vhci[,vlan=n]\n" \ " add host computer to virtual scatternet 'n' using VHCI\n" \ "-bt device:dev[,vlan=n]\n" \ " emulate a bluetooth device 'dev' in scatternet 'n'\n", QEMU_ARCH_ALL) STEXI @item -bt hci[...] @findex -bt Defines the function of the corresponding Bluetooth HCI. -bt options are matched with the HCIs present in the chosen machine type. For example when emulating a machine with only one HCI built into it, only the first @code{-bt hci[...]} option is valid and defines the HCI's logic. The Transport Layer is decided by the machine type. Currently the machines @code{n800} and @code{n810} have one HCI and all other machines have none. @anchor{bt-hcis} The following three types are recognized: @table @option @item -bt hci,null (default) The corresponding Bluetooth HCI assumes no internal logic and will not respond to any HCI commands or emit events. @item -bt hci,host[:@var{id}] (@code{bluez} only) The corresponding HCI passes commands / events to / from the physical HCI identified by the name @var{id} (default: @code{hci0}) on the computer running QEMU. Only available on @code{bluez} capable systems like Linux. @item -bt hci[,vlan=@var{n}] Add a virtual, standard HCI that will participate in the Bluetooth scatternet @var{n} (default @code{0}). Similarly to @option{-net} VLANs, devices inside a bluetooth network @var{n} can only communicate with other devices in the same network (scatternet). @end table @item -bt vhci[,vlan=@var{n}] (Linux-host only) Create a HCI in scatternet @var{n} (default 0) attached to the host bluetooth stack instead of to the emulated target. This allows the host and target machines to participate in a common scatternet and communicate. Requires the Linux @code{vhci} driver installed. Can be used as following: @example qemu-system-i386 [...OPTIONS...] -bt hci,vlan=5 -bt vhci,vlan=5 @end example @item -bt device:@var{dev}[,vlan=@var{n}] Emulate a bluetooth device @var{dev} and place it in network @var{n} (default @code{0}). QEMU can only emulate one type of bluetooth devices currently: @table @option @item keyboard Virtual wireless keyboard implementing the HIDP bluetooth profile. @end table ETEXI 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", 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 Backend type must be: @option{passthrough}. 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. Options to each backend are described below. Use 'help' to print all available TPM backend types. @example qemu -tpmdev help @end example @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. @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 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 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 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 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 STEXI @end table ETEXI DEFHEADING() DEFHEADING(Debug/Expert options:) STEXI @table @option ETEXI DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg, "-fw_cfg [name=],file=\n" " add named fw_cfg entry with contents from file\n" "-fw_cfg [name=],string=\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 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 step 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 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 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 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 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 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 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \ "-mon [chardev=]name[,mode=readline|control][,default]\n", QEMU_ARCH_ALL) STEXI @item -mon [chardev=]name[,mode=readline|control][,default] @findex -mon Setup monitor on chardev @var{name}. ETEXI 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 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 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 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 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 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 qemu-system-i386 -gdb stdio ... @end example ETEXI 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 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 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 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 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. ETEXI 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 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 DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid, "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL) DEF("xen-create", 0, QEMU_OPTION_xen_create, "-xen-create create domain using xen hypercalls, bypassing xend\n" " warning: should not be used when xend is in use\n", QEMU_ARCH_ALL) DEF("xen-attach", 0, QEMU_OPTION_xen_attach, "-xen-attach attach to existing xen domain\n" " xend will use this when starting QEMU\n", QEMU_ARCH_ALL) STEXI @item -xen-domid @var{id} @findex -xen-domid Specify xen guest domain @var{id} (XEN only). @item -xen-create @findex -xen-create Create domain using xen hypercalls, bypassing xend. Warning: should not be used when xend is in use (XEN only). @item -xen-attach @findex -xen-attach Attach to existing xen domain. xend will use this when starting QEMU (XEN only). ETEXI 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 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 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 #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 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 HXCOMM Silently ignored for compatibility DEF("clock", HAS_ARG, QEMU_OPTION_clock, "", QEMU_ARCH_ALL) HXCOMM Options deprecated by -rtc DEF("localtime", 0, QEMU_OPTION_localtime, "", QEMU_ARCH_ALL) DEF("startdate", HAS_ARG, QEMU_OPTION_startdate, "", QEMU_ARCH_ALL) DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \ "-rtc [base=utc|localtime|date][,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{date}][,clock=host|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{date} 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. To even prevent it from progressing during suspension, you can set it to @code{vm}. 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 DEF("icount", HAS_ARG, QEMU_OPTION_icount, \ "-icount [shift=N|auto][,align=on|off][,sleep=on|off,rr=record|replay,rrfile=]\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}] @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. ETEXI 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 DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \ "-watchdog-action reset|shutdown|poweroff|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{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 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 DEF("virtioconsole", HAS_ARG, QEMU_OPTION_virtiocon, \ "-virtioconsole c\n" \ " set virtio console\n", QEMU_ARCH_ALL) STEXI @item -virtioconsole @var{c} @findex -virtioconsole Set virtio console. This option is maintained for backward compatibility. Please use @code{-device virtconsole} for the new way of invocation. ETEXI 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 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 TB size. ETEXI 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 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 #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 #ifndef _WIN32 DEF("runas", HAS_ARG, QEMU_OPTION_runas, \ "-runas user change to user id user just before starting the VM\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 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). ETEXI 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) STEXI @item -semihosting @findex -semihosting Enable semihosting mode (ARM, M68K, Xtensa, MIPS only). ETEXI DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, "-semihosting-config [enable=on|off][,target=native|gdb|auto][,arg=str[,...]]\n" \ " semihosting configuration\n", QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 | QEMU_ARCH_MIPS) STEXI @item -semihosting-config [enable=on|off][,target=native|gdb|auto][,arg=str[,...]] @findex -semihosting-config Enable and configure semihosting (ARM, M68K, Xtensa, MIPS only). @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 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 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 DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ "-sandbox Enable seccomp mode 2 system call filter (default 'off').\n", QEMU_ARCH_ALL) STEXI @item -sandbox @var{arg} @findex -sandbox Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will disable it. The default is 'off'. ETEXI DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig, "-readconfig \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 DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig, "-writeconfig \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 DEF("nodefconfig", 0, QEMU_OPTION_nodefconfig, "-nodefconfig\n" " do not load default config files at startup\n", QEMU_ARCH_ALL) STEXI @item -nodefconfig @findex -nodefconfig Normally QEMU loads configuration files from @var{sysconfdir} and @var{datadir} at startup. The @code{-nodefconfig} option will prevent QEMU from loading any of those config files. ETEXI DEF("no-user-config", 0, QEMU_OPTION_nouserconfig, "-no-user-config\n" " do not load 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}, but won't make it skip the QEMU-provided config files from @var{datadir}. ETEXI DEF("trace", HAS_ARG, QEMU_OPTION_trace, "-trace [[enable=]][,events=][,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 [events=@var{file}][,file=@var{file}] @findex -trace Specify tracing options. @table @option @item [enable=]@var{pattern} Immediately enable events matching @var{pattern}. The file must contain one event name (as listed in the @file{trace-events} file) per line; globbing patterns are accepted too. This option is only available if QEMU has been compiled with the @var{simple}, @var{stderr} or @var{ftrace} tracing backend. To specify multiple events or patterns, specify the @option{-trace} option multiple times. Use @code{-trace help} to print a list of names of trace points. @item events=@var{file} Immediately enable events listed in @var{file}. The file must contain one event name (as listed in the @file{trace-events} file) per line; globbing patterns are accepted too. This option is only available if QEMU has been compiled with the @var{simple}, @var{stderr} or @var{ftrace} tracing backend. @item file=@var{file} Log output traces to @var{file}. This option is only available if QEMU has been compiled with the @var{simple} tracing backend. @end table ETEXI 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 HXCOMM Deprecated by -machine accel=tcg property DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386) HXCOMM Deprecated by kvm-pit driver properties DEF("no-kvm-pit-reinjection", 0, QEMU_OPTION_no_kvm_pit_reinjection, "", QEMU_ARCH_I386) HXCOMM Deprecated (ignored) DEF("no-kvm-pit", 0, QEMU_OPTION_no_kvm_pit, "", QEMU_ARCH_I386) HXCOMM Deprecated by -machine kernel_irqchip=on|off property DEF("no-kvm-irqchip", 0, QEMU_OPTION_no_kvm_irqchip, "", QEMU_ARCH_I386) HXCOMM Deprecated (ignored) DEF("tdf", 0, QEMU_OPTION_tdf,"", QEMU_ARCH_ALL) DEF("msg", HAS_ARG, QEMU_OPTION_msg, "-msg timestamp[=on|off]\n" " change the format of messages\n" " on|off controls leading timestamps (default:on)\n", QEMU_ARCH_ALL) STEXI @item -msg timestamp[=on|off] @findex -msg prepend a timestamp to each log message.(default:on) ETEXI DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate, "-dump-vmstate \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 DEFHEADING(Generic object creation) 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} 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. @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/random}. @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-x509,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/cred/dir},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. @item -object filter-buffer,id=@var{id},netdev=@var{netdevid},interval=@var{t}[,queue=@var{all|rx|tx}][,status=@var{on|off}] 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. @item -object filter-mirror,id=@var{id},netdev=@var{netdevid},outdev=@var{chardevid}[,queue=@var{all|rx|tx}] filter-mirror on netdev @var{netdevid},mirror net packet to chardev @var{chardevid} @item -object filter-redirector,id=@var{id},netdev=@var{netdevid},indev=@var{chardevid}, outdev=@var{chardevid}[,queue=@var{all|rx|tx}] filter-redirector on netdev @var{netdevid},redirect filter's net packet to chardev @var{chardevid},and redirect indev's packet to filter. 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-dump,id=@var{id},netdev=@var{dev},file=@var{filename}][,maxlen=@var{len}] 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 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 # $QEMU -object secret,id=sec0,data=letmein,format=raw @end example The simplest secure usage is to provide the secret via a file # echo -n "letmein" > mypasswd.txt # $QEMU -object secret,id=sec0,file=mypasswd.txt,format=raw For greater security, AES-256-CBC should be used. To illustrate usage, consider the openssl command line tool which can encrypt the data. Note that when encrypting, the plaintext must be padded to the cipher block size (32 bytes) using the standard PKCS#5/6 compatible padding algorithm. First a master key needs to be created in base64 encoding: @example # openssl rand -base64 32 > key.b64 # KEY=$(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=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"') @end example The secret to be defined can now be encrypted, in this case we're telling openssl to base64 encode the result, but it could be left as raw bytes if desired. @example # SECRET=$(echo -n "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 # $QEMU \ -object secret,id=secmaster0,format=base64,file=key.b64 \ -object secret,id=sec0,keyid=secmaster0,format=base64,\ data=$SECRET,iv=$(