\input texinfo @c -*- texinfo -*- @iftex @settitle QEMU CPU Emulator User Documentation @titlepage @sp 7 @center @titlefont{QEMU CPU Emulator User Documentation} @sp 3 @end titlepage @end iftex @chapter Introduction @section Features QEMU is a FAST! processor emulator using dynamic translation to achieve good emulation speed. QEMU has two operating modes: @itemize @minus @item Full system emulation. In this mode, QEMU emulates a full system (for example a PC), including a processor and various peripherials. It can be used to launch different Operating Systems without rebooting the PC or to debug system code. @item User mode emulation (Linux host only). In this mode, QEMU can launch Linux processes compiled for one CPU on another CPU. It can be used to launch the Wine Windows API emulator (@url{http://www.winehq.org}) or to ease cross-compilation and cross-debugging. @end itemize As QEMU requires no host kernel driver to run, it is very safe and easy to use. For system emulation, the following hardware targets are supported: @itemize @item PC (x86 processor) @item PREP (PowerPC processor) @item PowerMac (PowerPC processor, in progress) @end itemize For user emulation, x86, PowerPC, ARM, and SPARC CPUs are supported. @chapter Installation If you want to compile QEMU yourself, see @ref{compilation}. @section Linux Download the binary distribution (@file{qemu-XXX-i386.tar.gz}) and untar it as root in @file{/}: @example su cd / tar zxvf /tmp/qemu-XXX-i386.tar.gz @end example @section Windows Download the experimental binary installer at @url{http://www.freeoszoo.org/download.php}. @section Mac OS X Download the experimental binary installer at @url{http://www.freeoszoo.org/download.php}. @chapter QEMU PC System emulator invocation @section Introduction @c man begin DESCRIPTION The QEMU System emulator simulates a complete PC. In order to meet specific user needs, two versions of QEMU are available: @enumerate @item @code{qemu-fast} uses the host Memory Management Unit (MMU) to simulate the x86 MMU. It is @emph{fast} but has limitations because the whole 4 GB address space cannot be used and some memory mapped peripherials cannot be emulated accurately yet. Therefore, a specific guest Linux kernel can be used (@xref{linux_compile}) as guest OS. Moreover there is no separation between the host and target address spaces, so it offers no security (the target OS can modify the @code{qemu-fast} code by writing at the right addresses). @item @code{qemu} uses a software MMU. It is about @emph{two times slower} but gives a more accurate emulation and a complete separation between the host and target address spaces. @end enumerate QEMU emulates the following PC peripherials: @itemize @minus @item i440FX host PCI bridge and PIIX3 PCI to ISA bridge @item Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA extensions (hardware level, including all non standard modes). @item PS/2 mouse and keyboard @item 2 PCI IDE interfaces with hard disk and CD-ROM support @item Floppy disk @item NE2000 PCI network adapters @item Serial ports @item Soundblaster 16 card @end itemize QEMU uses the PC BIOS from the Bochs project and the Plex86/Bochs LGPL VGA BIOS. @c man end @section Quick Start Download and uncompress the linux image (@file{linux.img}) and type: @example qemu linux.img @end example Linux should boot and give you a prompt. @section Invocation @example @c man begin SYNOPSIS usage: qemu [options] [disk_image] @c man end @end example @c man begin OPTIONS @var{disk_image} is a raw hard disk image for IDE hard disk 0. General options: @table @option @item -fda file @item -fdb file Use @var{file} as floppy disk 0/1 image (@xref{disk_images}). You can use the host floppy by using @file{/dev/fd0} as filename. @item -hda file @item -hdb file @item -hdc file @item -hdd file Use @var{file} as hard disk 0, 1, 2 or 3 image (@xref{disk_images}). @item -cdrom file Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and and @option{-cdrom} at the same time). You can use the host CD-ROM by using @file{/dev/cdrom} as filename. @item -boot [a|c|d] Boot on floppy (a), hard disk (c) or CD-ROM (d). Hard disk boot is the default. @item -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} (@xref{disk_images}). @item -m megs Set virtual RAM size to @var{megs} megabytes. Default is 128 MB. @item -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. Therefore, you can still use QEMU to debug a Linux kernel with a serial console. @item -enable-audio The SB16 emulation is disabled by default as it may give problems with Windows. You can enable it manually with this option. @item -localtime Set the real time clock to local time (the default is to UTC time). This option is needed to have correct date in MS-DOS or Windows. @item -full-screen Start in full screen. @end table Network options: @table @option @item -n script Set TUN/TAP network init script [default=/etc/qemu-ifup]. This script is launched to configure the host network interface (usually tun0) corresponding to the virtual NE2000 card. @item -macaddr addr Set the mac address of the first interface (the format is aa:bb:cc:dd:ee:ff in hexa). The mac address is incremented for each new network interface. @item -tun-fd fd Assumes @var{fd} talks to a tap/tun host network interface and use it. Read @url{http://bellard.org/qemu/tetrinet.html} to have an example of its use. @item -user-net Use the user mode network stack. This is the default if no tun/tap network init script is found. @item -tftp prefix When using the user mode network stack, activate a built-in TFTP server. All filenames beginning with @var{prefix} can be downloaded from the host to the guest using a TFTP client. The TFTP client on the guest must be configured in binary mode (use the command @code{bin} of the Unix TFTP client). The host IP address on the guest is as usual 10.0.2.2. @item -smb dir 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{dir} transparently. 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{dir} can be accessed in @file{\\smbserver\qemu}. Note that a SAMBA server must be installed on the host OS in @file{/usr/sbin/smbd}. QEMU was tested succesfully with smbd version 2.2.7a from the Red Hat 9. @item -redir [tcp|udp]:host-port:[guest-host]:guest-port When using the user mode network stack, redirect incoming TCP or UDP connections to the host port @var{host-port} to the guest @var{guest-host} on guest port @var{guest-port}. If @var{guest-host} is not specified, its value is 10.0.2.15 (default address given by the built-in DHCP server). For example, to redirect host X11 connection from screen 1 to guest screen 0, use the following: @example # on the host qemu -redir tcp: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 -redir 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 -dummy-net Use the dummy network stack: no packet will be received by the network cards. @end table Linux boot specific. When using this options, you can use a given Linux kernel without installing it in the disk image. It can be useful for easier testing of various kernels. @table @option @item -kernel bzImage Use @var{bzImage} as kernel image. @item -append cmdline Use @var{cmdline} as kernel command line @item -initrd file Use @var{file} as initial ram disk. @end table Debug/Expert options: @table @option @item -serial dev Redirect the virtual serial port to host device @var{dev}. Available devices are: @table @code @item vc Virtual console @item pty [Linux only] Pseudo TTY (a new PTY is automatically allocated) @item null void device @item stdio [Unix only] standard input/output @end table 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 serials ports. @item -monitor dev 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. @item -s Wait gdb connection to port 1234 (@xref{gdb_usage}). @item -p port Change gdb connection port. @item -S Do not start CPU at startup (you must type 'c' in the monitor). @item -d Output log in /tmp/qemu.log @item -isa Simulate an ISA-only system (default is PCI system). @item -std-vga Simulate a standard VGA card with Bochs VBE extensions (default is Cirrus Logic GD5446 PCI VGA) @item -loadvm file Start right away with a saved state (@code{loadvm} in monitor) @end table @c man end @section Keys @c man begin OPTIONS During the graphical emulation, you can use the following keys: @table @key @item Ctrl-Alt-f Toggle full screen @item Ctrl-Alt-n Switch to virtual console 'n'. Standard console mappings are: @table @emph @item 1 Target system display @item 2 Monitor @item 3 Serial port @end table @item Ctrl-Alt Toggle mouse and keyboard grab. @end table In the virtual consoles, you can use @key{Ctrl-Up}, @key{Ctrl-Down}, @key{Ctrl-PageUp} and @key{Ctrl-PageDown} to move in the back log. During emulation, if you are using the @option{-nographic} option, use @key{Ctrl-a h} to get terminal commands: @table @key @item Ctrl-a h Print this help @item Ctrl-a x Exit emulatior @item Ctrl-a s Save disk data back to file (if -snapshot) @item Ctrl-a b Send break (magic sysrq in Linux) @item Ctrl-a c Switch between console and monitor @item Ctrl-a Ctrl-a Send Ctrl-a @end table @c man end @ignore @setfilename qemu @settitle QEMU System Emulator @c man begin SEEALSO The HTML documentation of QEMU for more precise information and Linux user mode emulator invocation. @c man end @c man begin AUTHOR Fabrice Bellard @c man end @end ignore @end ignore @section QEMU Monitor The QEMU monitor is used to give complex commands to the QEMU emulator. You can use it to: @itemize @minus @item Remove or insert removable medias images (such as CD-ROM or floppies) @item Freeze/unfreeze the Virtual Machine (VM) and save or restore its state from a disk file. @item Inspect the VM state without an external debugger. @end itemize @subsection Commands The following commands are available: @table @option @item help or ? [cmd] Show the help for all commands or just for command @var{cmd}. @item commit Commit changes to the disk images (if -snapshot is used) @item info subcommand show various information about the system state @table @option @item info network show the network state @item info block show the block devices @item info registers show the cpu registers @item info history show the command line history @end table @item q or quit Quit the emulator. @item eject [-f] device Eject a removable media (use -f to force it). @item change device filename Change a removable media. @item screendump filename Save screen into PPM image @var{filename}. @item log item1[,...] Activate logging of the specified items to @file{/tmp/qemu.log}. @item savevm filename Save the whole virtual machine state to @var{filename}. @item loadvm filename Restore the whole virtual machine state from @var{filename}. @item stop Stop emulation. @item c or cont Resume emulation. @item gdbserver [port] Start gdbserver session (default port=1234) @item x/fmt addr Virtual memory dump starting at @var{addr}. @item xp /fmt addr Physical memory dump starting at @var{addr}. @var{fmt} is a format which tells the command how to format the data. Its syntax is: @option{/@{count@}@{format@}@{size@}} @table @var @item count is the number of items to be dumped. @item format can be x (hexa), d (signed decimal), u (unsigned decimal), o (octal), c (char) or i (asm instruction). @item size can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits). On x86, @code{h} or @code{w} can be specified with the @code{i} format to respectively select 16 or 32 bit code instruction size. @end table Examples: @itemize @item Dump 10 instructions at the current instruction pointer: @example (qemu) x/10i $eip 0x90107063: ret 0x90107064: sti 0x90107065: lea 0x0(%esi,1),%esi 0x90107069: lea 0x0(%edi,1),%edi 0x90107070: ret 0x90107071: jmp 0x90107080 0x90107073: nop 0x90107074: nop 0x90107075: nop 0x90107076: nop @end example @item Dump 80 16 bit values at the start of the video memory. @example (qemu) xp/80hx 0xb8000 0x000b8000: 0x0b50 0x0b6c 0x0b65 0x0b78 0x0b38 0x0b36 0x0b2f 0x0b42 0x000b8010: 0x0b6f 0x0b63 0x0b68 0x0b73 0x0b20 0x0b56 0x0b47 0x0b41 0x000b8020: 0x0b42 0x0b69 0x0b6f 0x0b73 0x0b20 0x0b63 0x0b75 0x0b72 0x000b8030: 0x0b72 0x0b65 0x0b6e 0x0b74 0x0b2d 0x0b63 0x0b76 0x0b73 0x000b8040: 0x0b20 0x0b30 0x0b35 0x0b20 0x0b4e 0x0b6f 0x0b76 0x0b20 0x000b8050: 0x0b32 0x0b30 0x0b30 0x0b33 0x0720 0x0720 0x0720 0x0720 0x000b8060: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x000b8070: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x000b8080: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x000b8090: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 @end example @end itemize @item p or print/fmt expr Print expression value. Only the @var{format} part of @var{fmt} is used. @item sendkey keys Send @var{keys} to the emulator. Use @code{-} to press several keys simultaneously. Example: @example sendkey ctrl-alt-f1 @end example This command is useful to send keys that your graphical user interface intercepts at low level, such as @code{ctrl-alt-f1} in X Window. @item system_reset Reset the system. @end table @subsection Integer expressions The monitor understands integers expressions for every integer argument. You can use register names to get the value of specifics CPU registers by prefixing them with @emph{$}. @node disk_images @section Disk Images @subsection Raw disk images The disk images can simply be raw images of the hard disk. You can create them with the command: @example dd of=myimage bs=1024 seek=mysize count=0 @end example where @var{myimage} is the image filename and @var{mysize} is its size in kilobytes. @subsection Snapshot mode If you use the option @option{-snapshot}, all disk images are considered as read only. When sectors in written, they are written in a temporary file created in @file{/tmp}. You can however force the write back to the raw disk images by pressing @key{C-a s}. NOTE: The snapshot mode only works with raw disk images. @subsection Copy On Write disk images QEMU also supports user mode Linux (@url{http://user-mode-linux.sourceforge.net/}) Copy On Write (COW) disk images. The COW disk images are much smaller than normal images as they store only modified sectors. They also permit the use of the same disk image template for many users. To create a COW disk images, use the command: @example qemu-mkcow -f myrawimage.bin mycowimage.cow @end example @file{myrawimage.bin} is a raw image you want to use as original disk image. It will never be written to. @file{mycowimage.cow} is the COW disk image which is created by @code{qemu-mkcow}. You can use it directly with the @option{-hdx} options. You must not modify the original raw disk image if you use COW images, as COW images only store the modified sectors from the raw disk image. QEMU stores the original raw disk image name and its modified time in the COW disk image so that chances of mistakes are reduced. If the raw disk image is not read-only, by pressing @key{C-a s} you can flush the COW disk image back into the raw disk image, as in snapshot mode. COW disk images can also be created without a corresponding raw disk image. It is useful to have a big initial virtual disk image without using much disk space. Use: @example qemu-mkcow mycowimage.cow 1024 @end example to create a 1 gigabyte empty COW disk image. NOTES: @enumerate @item COW disk images must be created on file systems supporting @emph{holes} such as ext2 or ext3. @item Since holes are used, the displayed size of the COW disk image is not the real one. To know it, use the @code{ls -ls} command. @end enumerate @subsection Convert VMware disk images to raw disk images You can use the tool @file{vmdk2raw} to convert VMware disk images to raw disk images directly usable by QEMU. The syntax is: @example vmdk2raw vmware_image output_image @end example @section Network emulation QEMU simulates up to 6 networks cards (NE2000 boards). Each card can be connected to a specific host network interface. @subsection Using tun/tap network interface This is the standard way to emulate network. QEMU adds a virtual network device on your host (called @code{tun0}), and you can then configure it as if it was a real ethernet card. As an example, you can download the @file{linux-test-xxx.tar.gz} archive and copy the script @file{qemu-ifup} in @file{/etc} and configure properly @code{sudo} so that the command @code{ifconfig} contained in @file{qemu-ifup} can be executed as root. You must verify that your host kernel supports the TUN/TAP network interfaces: the device @file{/dev/net/tun} must be present. See @ref{direct_linux_boot} to have an example of network use with a Linux distribution. @subsection Using the user mode network stack By using the option @option{-user-net} or if you have no tun/tap init script, QEMU uses a completely user mode network stack (you don't need root priviledge to use the virtual network). The virtual network configuration is the following: @example QEMU Virtual Machine <------> Firewall/DHCP server <-----> Internet (10.0.2.x) | (10.0.2.2) | ----> DNS server (10.0.2.3) | ----> SMB server (10.0.2.4) @end example The QEMU VM behaves as if it was behind a firewall which blocks all incoming connections. You can use a DHCP client to automatically configure the network in the QEMU VM. In order to check that the user mode network is working, you can ping the address 10.0.2.2 and verify that you got an address in the range 10.0.2.x from the QEMU virtual DHCP server. Note that @code{ping} is not supported reliably to the internet as it would require root priviledges. It means you can only ping the local router (10.0.2.2). When using the built-in TFTP server, the router is also the TFTP server. When using the @option{-redir} option, TCP or UDP connections can be redirected from the host to the guest. It allows for example to redirect X11, telnet or SSH connections. @node direct_linux_boot @section Direct Linux Boot This section explains how to launch a Linux kernel inside QEMU without having to make a full bootable image. It is very useful for fast Linux kernel testing. The QEMU network configuration is also explained. @enumerate @item Download the archive @file{linux-test-xxx.tar.gz} containing a Linux kernel and a disk image. @item Optional: If you want network support (for example to launch X11 examples), you must copy the script @file{qemu-ifup} in @file{/etc} and configure properly @code{sudo} so that the command @code{ifconfig} contained in @file{qemu-ifup} can be executed as root. You must verify that your host kernel supports the TUN/TAP network interfaces: the device @file{/dev/net/tun} must be present. When network is enabled, there is a virtual network connection between the host kernel and the emulated kernel. The emulated kernel is seen from the host kernel at IP address 172.20.0.2 and the host kernel is seen from the emulated kernel at IP address 172.20.0.1. @item Launch @code{qemu.sh}. You should have the following output: @example > ./qemu.sh Connected to host network interface: tun0 Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003 BIOS-provided physical RAM map: BIOS-e801: 0000000000000000 - 000000000009f000 (usable) BIOS-e801: 0000000000100000 - 0000000002000000 (usable) 32MB LOWMEM available. On node 0 totalpages: 8192 zone(0): 4096 pages. zone(1): 4096 pages. zone(2): 0 pages. Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe console=ttyS0 ide_setup: ide2=noprobe ide_setup: ide3=noprobe ide_setup: ide4=noprobe ide_setup: ide5=noprobe Initializing CPU#0 Detected 2399.621 MHz processor. Console: colour EGA 80x25 Calibrating delay loop... 4744.80 BogoMIPS Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, 0k highmem) Dentry cache hash table entries: 4096 (order: 3, 32768 bytes) Inode cache hash table entries: 2048 (order: 2, 16384 bytes) Mount cache hash table entries: 512 (order: 0, 4096 bytes) Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes) Page-cache hash table entries: 8192 (order: 3, 32768 bytes) CPU: Intel Pentium Pro stepping 03 Checking 'hlt' instruction... OK. POSIX conformance testing by UNIFIX Linux NET4.0 for Linux 2.4 Based upon Swansea University Computer Society NET3.039 Initializing RT netlink socket apm: BIOS not found. Starting kswapd Journalled Block Device driver loaded Detected PS/2 Mouse Port. pty: 256 Unix98 ptys configured Serial driver version 5.05c (2001-07-08) with no serial options enabled ttyS00 at 0x03f8 (irq = 4) is a 16450 ne.c:v1.10 9/23/94 Donald Becker (becker@scyld.com) Last modified Nov 1, 2000 by Paul Gortmaker NE*000 ethercard probe at 0x300: 52 54 00 12 34 56 eth0: NE2000 found at 0x300, using IRQ 9. RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4 ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx hda: QEMU HARDDISK, ATA DISK drive ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 hda: attached ide-disk driver. hda: 20480 sectors (10 MB) w/256KiB Cache, CHS=20/16/63 Partition check: hda: Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996 NET4: Linux TCP/IP 1.0 for NET4.0 IP Protocols: ICMP, UDP, TCP, IGMP IP: routing cache hash table of 512 buckets, 4Kbytes TCP: Hash tables configured (established 2048 bind 4096) NET4: Unix domain sockets 1.0/SMP for Linux NET4.0. EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended VFS: Mounted root (ext2 filesystem). Freeing unused kernel memory: 64k freed Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003 QEMU Linux test distribution (based on Redhat 9) Type 'exit' to halt the system sh-2.05b# @end example @item Then you can play with the kernel inside the virtual serial console. You can launch @code{ls} for example. Type @key{Ctrl-a h} to have an help about the keys you can type inside the virtual serial console. In particular, use @key{Ctrl-a x} to exit QEMU and use @key{Ctrl-a b} as the Magic SysRq key. @item If the network is enabled, launch the script @file{/etc/linuxrc} in the emulator (don't forget the leading dot): @example . /etc/linuxrc @end example Then enable X11 connections on your PC from the emulated Linux: @example xhost +172.20.0.2 @end example You can now launch @file{xterm} or @file{xlogo} and verify that you have a real Virtual Linux system ! @end enumerate NOTES: @enumerate @item A 2.5.74 kernel is also included in the archive. Just replace the bzImage in qemu.sh to try it. @item qemu-fast creates a temporary file in @var{$QEMU_TMPDIR} (@file{/tmp} is the default) containing all the simulated PC memory. If possible, try to use a temporary directory using the tmpfs filesystem to avoid too many unnecessary disk accesses. @item In order to exit cleanly from qemu, you can do a @emph{shutdown} inside qemu. qemu will automatically exit when the Linux shutdown is done. @item You can boot slightly faster by disabling the probe of non present IDE interfaces. To do so, add the following options on the kernel command line: @example ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe @end example @item The example disk image is a modified version of the one made by Kevin Lawton for the plex86 Project (@url{www.plex86.org}). @end enumerate @node linux_compile @section Linux Kernel Compilation You can use any linux kernel with QEMU. However, if you want to use @code{qemu-fast} to get maximum performances, you must use a modified guest kernel. If you are using a 2.6 guest kernel, you can use directly the patch @file{linux-2.6-qemu-fast.patch} made by Rusty Russel available in the QEMU source archive. Otherwise, you can make the following changes @emph{by hand} to the Linux kernel: @enumerate @item The kernel must be mapped at 0x90000000 (the default is 0xc0000000). You must modify only two lines in the kernel source: In @file{include/asm/page.h}, replace @example #define __PAGE_OFFSET (0xc0000000) @end example by @example #define __PAGE_OFFSET (0x90000000) @end example And in @file{arch/i386/vmlinux.lds}, replace @example . = 0xc0000000 + 0x100000; @end example by @example . = 0x90000000 + 0x100000; @end example @item If you want to enable SMP (Symmetric Multi-Processing) support, you must make the following change in @file{include/asm/fixmap.h}. Replace @example #define FIXADDR_TOP (0xffffX000UL) @end example by @example #define FIXADDR_TOP (0xa7ffX000UL) @end example (X is 'e' or 'f' depending on the kernel version). Although you can use an SMP kernel with QEMU, it only supports one CPU. @item If you are not using a 2.6 kernel as host kernel but if you use a target 2.6 kernel, you must also ensure that the 'HZ' define is set to 100 (1000 is the default) as QEMU cannot currently emulate timers at frequencies greater than 100 Hz on host Linux systems < 2.6. In @file{include/asm/param.h}, replace: @example # define HZ 1000 /* Internal kernel timer frequency */ @end example by @example # define HZ 100 /* Internal kernel timer frequency */ @end example @end enumerate The file config-2.x.x gives the configuration of the example kernels. Just type @example make bzImage @end example As you would do to make a real kernel. Then you can use with QEMU exactly the same kernel as you would boot on your PC (in @file{arch/i386/boot/bzImage}). @node gdb_usage @section GDB usage QEMU has a primitive support to work with gdb, so that you can do 'Ctrl-C' while the virtual machine is running and inspect its state. In order to use gdb, launch qemu with the '-s' option. It will wait for a gdb connection: @example > qemu -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda" Connected to host network interface: tun0 Waiting gdb connection on port 1234 @end example Then launch gdb on the 'vmlinux' executable: @example > gdb vmlinux @end example In gdb, connect to QEMU: @example (gdb) target remote localhost:1234 @end example Then you can use gdb normally. For example, type 'c' to launch the kernel: @example (gdb) c @end example Here are some useful tips in order to use gdb on system code: @enumerate @item Use @code{info reg} to display all the CPU registers. @item Use @code{x/10i $eip} to display the code at the PC position. @item Use @code{set architecture i8086} to dump 16 bit code. Then use @code{x/10i $cs*16+*eip} to dump the code at the PC position. @end enumerate @section Target OS specific information @subsection Linux To have access to SVGA graphic modes under X11, use the @code{vesa} or the @code{cirrus} X11 driver. For optimal performances, use 16 bit color depth in the guest and the host OS. When using a 2.6 guest Linux kernel, you should add the option @code{clock=pit} on the kernel command line because the 2.6 Linux kernels make very strict real time clock checks by default that QEMU cannot simulate exactly. @subsection Windows If you have a slow host, using Windows 95 is better as it gives the best speed. Windows 2000 is also a good choice. @subsubsection SVGA graphic modes support QEMU emulates a 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. @subsubsection CPU usage reduction Windows 9x does not correctly use the CPU HLT instruction. The result is that it takes host CPU cycles even when idle. You can install the utility from @url{http://www.user.cityline.ru/~maxamn/amnhltm.zip} to solve this problem. Note that no such tool is needed for NT, 2000 or XP. @subsubsection Windows 2000 disk full problems Currently (release 0.6.0) QEMU has a bug which gives a @code{disk full} error during installation of some releases of Windows 2000. The workaround is to stop QEMU as soon as you notice that your disk image size is growing too fast (monitor it with @code{ls -ls}). Then relaunch QEMU to continue the installation. If you still experience the problem, relaunch QEMU again. Future QEMU releases are likely to correct this bug. @subsubsection Windows XP security problems Some releases of Windows XP install correctly but give a security error when booting: @example A problem is preventing Windows from accurately checking the license for this computer. Error code: 0x800703e6. @end example The only known workaround is to boot in Safe mode without networking support. Future QEMU releases are likely to correct this bug. @subsection MS-DOS and FreeDOS @subsubsection CPU usage reduction DOS does not correctly use the CPU HLT instruction. The result is that it takes host CPU cycles even when idle. You can install the utility from @url{http://www.vmware.com/software/dosidle210.zip} to solve this problem. @chapter QEMU PowerPC System emulator invocation Use the executable @file{qemu-system-ppc} to simulate a complete PREP or PowerMac PowerPC system. QEMU emulates the following PowerMac peripherials: @itemize @minus @item UniNorth PCI Bridge @item PCI VGA compatible card with VESA Bochs Extensions @item 2 PMAC IDE interfaces with hard disk and CD-ROM support @item NE2000 PCI adapters @item Non Volatile RAM @item VIA-CUDA with ADB keyboard and mouse. @end itemize QEMU emulates the following PREP peripherials: @itemize @minus @item PCI Bridge @item PCI VGA compatible card with VESA Bochs Extensions @item 2 IDE interfaces with hard disk and CD-ROM support @item Floppy disk @item NE2000 network adapters @item Serial port @item PREP Non Volatile RAM @item PC compatible keyboard and mouse. @end itemize QEMU uses the Open Hack'Ware Open Firmware Compatible BIOS available at @url{http://site.voila.fr/jmayer/OpenHackWare/index.htm}. You can read the qemu PC system emulation chapter to have more informations about QEMU usage. @c man begin OPTIONS The following options are specific to the PowerPC emulation: @table @option @item -prep Simulate a PREP system (default is PowerMAC) @item -g WxH[xDEPTH] Set the initial VGA graphic mode. The default is 800x600x15. @end table @c man end More information is available at @url{http://jocelyn.mayer.free.fr/qemu-ppc/}. @chapter QEMU User space emulator invocation @section Quick Start In order to launch a Linux process, QEMU needs the process executable itself and all the target (x86) dynamic libraries used by it. @itemize @item On x86, you can just try to launch any process by using the native libraries: @example qemu-i386 -L / /bin/ls @end example @code{-L /} tells that the x86 dynamic linker must be searched with a @file{/} prefix. @item Since QEMU is also a linux process, you can launch qemu with qemu (NOTE: you can only do that if you compiled QEMU from the sources): @example qemu-i386 -L / qemu-i386 -L / /bin/ls @end example @item On non x86 CPUs, you need first to download at least an x86 glibc (@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that @code{LD_LIBRARY_PATH} is not set: @example unset LD_LIBRARY_PATH @end example Then you can launch the precompiled @file{ls} x86 executable: @example qemu-i386 tests/i386/ls @end example You can look at @file{qemu-binfmt-conf.sh} so that QEMU is automatically launched by the Linux kernel when you try to launch x86 executables. It requires the @code{binfmt_misc} module in the Linux kernel. @item The x86 version of QEMU is also included. You can try weird things such as: @example qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386 @end example @end itemize @section Wine launch @itemize @item Ensure that you have a working QEMU with the x86 glibc distribution (see previous section). In order to verify it, you must be able to do: @example qemu-i386 /usr/local/qemu-i386/bin/ls-i386 @end example @item Download the binary x86 Wine install (@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page). @item Configure Wine on your account. Look at the provided script @file{/usr/local/qemu-i386/bin/wine-conf.sh}. Your previous @code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}. @item Then you can try the example @file{putty.exe}: @example qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe @end example @end itemize @section Command line options @example usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...] @end example @table @option @item -h Print the help @item -L path Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386) @item -s size Set the x86 stack size in bytes (default=524288) @end table Debug options: @table @option @item -d Activate log (logfile=/tmp/qemu.log) @item -p pagesize Act as if the host page size was 'pagesize' bytes @end table @node compilation @chapter Compilation from the sources @section Linux/BSD Read the @file{README} which gives the related information. @section Windows @itemize @item Install the current versions of MSYS and MinGW from @url{http://www.mingw.org/}. You can find detailed installation instructions in the download section and the FAQ. @item Download the MinGW development library of SDL 1.2.x (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from @url{http://www.libsdl.org}. Unpack it in a temporary place, and unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool directory. Edit the @file{sdl-config} script so that it gives the correct SDL directory when invoked. @item Extract the current version of QEMU. @item Start the MSYS shell (file @file{msys.bat}). @item Change to the QEMU directory. Launch @file{./configure} and @file{make}. If you have problems using SDL, verify that @file{sdl-config} can be launched from the MSYS command line. @item You can install QEMU in @file{Program Files/Qemu} by typing @file{make install}. Don't forget to copy @file{SDL.dll} in @file{Program Files/Qemu}. @end itemize @section Cross compilation for Windows with Linux @itemize @item Install the MinGW cross compilation tools available at @url{http://www.mingw.org/}. @item Install the Win32 version of SDL (@url{http://www.libsdl.org}) by unpacking @file{i386-mingw32msvc.tar.gz}. Set up the PATH environment variable so that @file{i386-mingw32msvc-sdl-config} can be launched by the QEMU configuration script. @item Configure QEMU for Windows cross compilation: @example ./configure --enable-mingw32 @end example If necessary, you can change the cross-prefix according to the prefix choosen for the MinGW tools with --cross-prefix. You can also use --prefix to set the Win32 install path. @item You can install QEMU in the installation directory by typing @file{make install}. Don't forget to copy @file{SDL.dll} in the installation directory. @end itemize Note: Currently, Wine does not seem able to launch QEMU for Win32. @section Mac OS X The Mac OS X patches are not fully merged in QEMU, so you should look at the QEMU mailing list archive to have all the necessary information.