qemu命令使用方法

时间：2022-03-04 18:47:14

QEMU Emulator User Documentation

Table of Contents

1 Introduction

1.1 Features

QEMU is a FAST! processor emulator using dynamic translation toachieve good emulation speed.

QEMU has two operating modes:

  • Full system emulation. In this mode, QEMU emulates a full system (forexample a PC), including one or several processors and variousperipherals. It can be used to launch different Operating Systemswithout rebooting the PC or to debug system code.
  • User mode emulation. In this mode, QEMU can launchprocesses compiled for one CPU on another CPU. It can be used tolaunch the Wine Windows API emulator (http://www.winehq.org) orto ease cross-compilation and cross-debugging.

QEMU can run without an host kernel driver and yet gives acceptableperformance.

For system emulation, the following hardware targets are supported:

  • PC (x86 or x86_64 processor)
  • ISA PC (old style PC without PCI bus)
  • PREP (PowerPC processor)
  • G3 Beige PowerMac (PowerPC processor)
  • Mac99 PowerMac (PowerPC processor, in progress)
  • Sun4m/Sun4c/Sun4d (32-bit Sparc processor)
  • Sun4u/Sun4v (64-bit Sparc processor, in progress)
  • Malta board (32-bit and 64-bit MIPS processors)
  • MIPS Magnum (64-bit MIPS processor)
  • ARM Integrator/CP (ARM)
  • ARM Versatile baseboard (ARM)
  • ARM RealView Emulation/Platform baseboard (ARM)
  • Spitz, Akita, Borzoi, Terrier and Tosa PDAs (PXA270 processor)
  • Luminary Micro LM3S811EVB (ARM Cortex-M3)
  • Luminary Micro LM3S6965EVB (ARM Cortex-M3)
  • Freescale MCF5208EVB (ColdFire V2).
  • Arnewsh MCF5206 evaluation board (ColdFire V2).
  • Palm Tungsten|E PDA (OMAP310 processor)
  • N800 and N810 tablets (OMAP2420 processor)
  • MusicPal (MV88W8618 ARM processor)
  • Gumstix "Connex" and "Verdex" motherboards (PXA255/270).
  • Siemens SX1 smartphone (OMAP310 processor)
  • AXIS-Devboard88 (CRISv32 ETRAX-FS).
  • Petalogix Spartan 3aDSP1800 MMU ref design (MicroBlaze).
  • Avnet LX60/LX110/LX200 boards (Xtensa)

For user emulation, x86 (32 and 64 bit), PowerPC (32 and 64 bit),ARM, MIPS (32 bit only), Sparc (32 and 64 bit),Alpha, ColdFire(m68k), CRISv32 and MicroBlaze CPUs are supported.

2 Installation

If you want to compile QEMU yourself, see compilation.

2.1 Linux

If a precompiled package is available for your distribution - you justhave to install it. Otherwise, see compilation.

2.2 Windows

Download the experimental binary installer athttp://www.free.oszoo.org/download.html. TODO (no longer available)

2.3 Mac OS X

Download the experimental binary installer athttp://www.free.oszoo.org/download.html. TODO (no longer available)

3 QEMU PC System emulator

3.1 Introduction

The QEMU PC System emulator simulates thefollowing peripherals:

  • i440FX host PCI bridge and PIIX3 PCI to ISA bridge
  • Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESAextensions (hardware level, including all non standard modes).
  • PS/2 mouse and keyboard
  • 2 PCI IDE interfaces with hard disk and CD-ROM support
  • Floppy disk
  • PCI and ISA network adapters
  • Serial ports
  • Creative SoundBlaster 16 sound card
  • ENSONIQ AudioPCI ES1370 sound card
  • Intel 82801AA AC97 Audio compatible sound card
  • Intel HD Audio Controller and HDA codec
  • Adlib (OPL2) - Yamaha YM3812 compatible chip
  • Gravis Ultrasound GF1 sound card
  • CS4231A compatible sound card
  • PCI UHCI USB controller and a virtual USB hub.

SMP is supported with up to 255 CPUs.

Note that adlib, gus and cs4231a are only available when QEMU wasconfigured with –audio-card-list option containing the name(s) ofrequired card(s).

QEMU uses the PC BIOS from the Bochs project and the Plex86/Bochs LGPLVGA BIOS.

QEMU uses YM3812 emulation by Tatsuyuki Satoh.

QEMU uses GUS emulation (GUSEMU32 http://www.deinmeister.de/gusemu/)by Tibor "TS" Schütz.

Note that, by default, GUS shares IRQ(7) with parallel ports and soQEMU must be told to not have parallel ports to have working GUS.

qemu-system-i386 dos.img -soundhw gus -parallel none

Alternatively:

qemu-system-i386 dos.img -device gus,irq=5

Or some other unclaimed IRQ.

CS4231A is the chip used in Windows Sound System and GUSMAX products

3.2 Quick Start

Download and uncompress the linux image (linux.img) and type:

qemu-system-i386 linux.img

Linux should boot and give you a prompt.

3.3 Invocation

usage: qemu-system-i386 [options] [disk_image]

disk_image is a raw hard disk image for IDE hard disk 0. Sometargets do not need a disk image.

Standard options:

-h
Display help and exit
-version
Display version information and exit
-machine [type=]name[,prop=value[,...]]
Select the emulated machine by name. Use -machine ? to listavailable machines. Supported machine properties are:
accel=accels1[: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 morethan one accelerator specified, the next one is used if the previous one failsto initialize.
kernel_irqchip=on|off
Enables in-kernel irqchip support for the chosen accelerator when available.
kvm_shadow_mem=size
Defines the size of the KVM shadow MMU.

-cpu model
Select CPU model (-cpu ? for list and additional feature selection)
-smp n[,cores=cores][,threads=threads][,sockets=sockets][,maxcpus=maxcpus]
Simulate an SMP system with n CPUs. On the PC target, up to 255CPUs are supported. On Sparc32 target, Linux limits the number of usable CPUsto 4. For the PC target, the number of cores per socket, the numberof threads per cores and the total number of sockets can bespecified. Missing values will be computed. If any on the three values isgiven, the total number of CPUs n can be omitted. maxcpusspecifies the maximum number of hotpluggable CPUs.
-numa opts
Simulate a multi node NUMA system. If mem and cpus are omitted, resourcesare split equally.
-fda file
-fdb file
Use file as floppy disk 0/1 image (see disk_images). You canuse the host floppy by using /dev/fd0 as filename (see host_drives).
-hda file
-hdb file
-hdc file
-hdd file
Use file as hard disk 0, 1, 2 or 3 image (see disk_images).
-cdrom file
Use file as CD-ROM image (you cannot use -hdc and -cdrom at the same time). You can use the host CD-ROM byusing /dev/cdrom as filename (see host_drives).
-drive option[,option[,option[,...]]]
Define a new drive. Valid options are:
file=file
This option defines which disk image (see disk_images) to use withthis 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 protocolspecific URLs. See the section for "Device URL Syntax" for more information.

if=interface
This option defines on which type on interface the drive is connected. Available types are: ide, scsi, sd, mtd, floppy, pflash, virtio.
bus=bus,unit=unit
These options define where is connected the drive by defining the bus number andthe unit id.
index=index
This option defines where is connected the drive by using an index in the listof available connectors of a given interface type.
media=media
This option defines the type of the media: disk or cdrom.
cyls=c,heads=h,secs=s[,trans=t]
These options have the same definition as they have in -hdachs.
snapshot=snapshot
snapshot is "on" or "off" and allows to enable snapshot for given drive (see -snapshot).
cache=cache
cache is "none", "writeback", "unsafe", "directsync" or "writethrough" and controls how the host cache is used to access block data.
aio=aio
aio is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO.
format=format
Specify which disk format will be used rather than detectingthe format. Can be used to specifiy format=raw to avoid interpretingan untrusted format header.
serial=serial
This option specifies the serial number to assign to the device.
addr=addr
Specify the controller's PCI address (if=virtio only).
werror=action,rerror=action
Specify which action to take on write and read errors. Valid actions are:"ignore" (ignore the error and try to continue), "stop" (pause QEMU),"report" (report the error to the guest), "enospc" (pause QEMU only if thehost disk is full; report the error to the guest otherwise). The default setting is werror=enospc and rerror=report.
readonly
Open drive file as read-only. Guest write attempts will fail.
copy-on-read=copy-on-read
copy-on-read is "on" or "off" and enables whether to copy read backingfile sectors into the image file.

By default, writethrough caching is used for all block device. This means thatthe host page cache will be used to read and write data but write notificationwill be sent to the guest only when the data has been reported as written bythe storage subsystem.

Writeback caching will report data writes as completed as soon as the data ispresent in the host page cache. This is safe as long as you trust your host. If your host crashes or loses power, then the guest may experience datacorruption.

The host page cache can be avoided entirely with cache=none. This willattempt to do disk IO directly to the guests memory. QEMU may still performan internal copy of the data.

The host page cache can be avoided while only sending write notifications tothe guest when the data has been reported as written by the storage subsystemusing cache=directsync.

Some block drivers perform badly with cache=writethrough, most notably,qcow2. If performance is more important than correctness,cache=writeback should be used with qcow2.

In case you don't care about data integrity over host failures, usecache=unsafe. This option tells QEMU that it never needs to write any datato the disk but can instead keeps things in cache. If anything goes wrong,like your host losing power, the disk storage getting disconnected accidentally,etc. you're image will most probably be rendered unusable. When usingthe -snapshot option, unsafe caching is always used.

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

Instead of -cdrom you can use: 

     qemu-system-i386 -drive file=file,index=2,media=cdrom

Instead of -hda, -hdb, -hdc, -hdd, you canuse: 

     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

You can connect a CDROM to the slave of ide0: 

     qemu-system-i386 -drive file=file,if=ide,index=1,media=cdrom

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

     qemu-system-i386 -drive if=ide,index=1,media=cdrom

You can connect a SCSI disk with unit ID 6 on the bus #0: 

     qemu-system-i386 -drive file=file,if=scsi,bus=0,unit=6

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

     qemu-system-i386 -drive file=file,index=0,if=floppy
     qemu-system-i386 -drive file=file,index=1,if=floppy

By default, interface is "ide" and index is automaticallyincremented: 

     qemu-system-i386 -drive file=a -drive file=b"

is interpreted like: 

     qemu-system-i386 -hda a -hdb b

-set
TODO
-global driver.prop=value
Set default value of driver's property prop to value, e.g.: 
     qemu-system-i386 -global ide-drive.physical_block_size=4096 -drive file=file,if=ide,index=0,media=disk

In particular, you can use this to set driver properties for devices which arecreated automatically by the machine model. To create a device which is notcreated automatically and set properties on it, use -device.

-mtdblock file
Use file as on-board Flash memory image.
-sd file
Use file as SecureDigital card image.
-pflash file
Use file as a parallel flash image.
-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time]
Specify boot order drives as a string of drive letters. Validdrive letters depend on the target achitecture. The x86 PC uses: a, b(floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p (Etherbootfrom network adapter 1-4), hard disk boot is the default. To apply aparticular boot order only on the first startup, specify it via once.

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

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

     # 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

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

-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 forcethe write back by pressing <C-a s> (see disk_images).
-m megs
Set virtual RAM size to megs megabytes. Default is 128 MiB. Optionally,a suffix of “M” or “G” can be used to signify a value in megabytes orgigabytes respectively.
-mem-path path
Allocate guest RAM from a temporarily created file in path.
-mem-prealloc
Preallocate memory when using -mem-path.
-k language
Use keyboard layout language (for example fr forFrench). This option is only needed where it is not easy to get raw PCkeycodes (e.g. on Macs, with some X11 servers or with a VNCdisplay). You don't normally need to use it on PC/Linux or PC/Windowshosts.

The available layouts are: 

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

The default is en-us.

-audio-help
Will show the audio subsystem help: list of drivers, tunableparameters.
-soundhw card1[,card2,...] or -soundhw all
Enable audio and selected sound hardware. Use ? to print allavailable sound hardware. 
     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 ?

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

     modprobe i810_audio clocking=48000

-balloon none
Disable balloon device.
-balloon virtio[,addr=addr]
Enable virtio balloon device (default), optionally with PCI address addr.
USB options:
-usb
Enable the USB driver (will be the default soon)
-usbdevice devname
Add the USB device devname. See usb_devices.
mouse
Virtual Mouse. This will override the PS/2 mouse emulation when activated.
tablet
Pointer device that uses absolute coordinates (like a touchscreen). Thismeans QEMU is able to report the mouse position without having to grab themouse. Also overrides the PS/2 mouse emulation when activated.
disk:[format=format]:file
Mass storage device based on file. The optional format argumentwill be used rather than detecting the format. Can be used to specifiy format=raw to avoid interpreting an untrusted format header.
host:bus.addr
Pass through the host device identified by bus. addr (Linux only).
host:vendor_id:product_id
Pass through the host device identified by vendor_id: product_id(Linux only).
serial:[vendorid=vendor_id][,productid=product_id]:dev
Serial converter to host character device dev, see -serial for theavailable devices.
braille
Braille device. This will use BrlAPI to display the braille output on a realor fake device.
net:options
Network adapter that supports CDC ethernet and RNDIS protocols.

-device driver[,prop[=value][,...]]
Add device driver. prop= value sets driverproperties. Valid properties depend on the driver. To get help onpossible drivers and properties, use -device ? and -device driver ,?.

File system options:

-fsdev fsdriver,id=id,path=path,[security_model=security_model][,writeout=writeout][,readonly][,socket=socket|sock_fd=sock_fd]
Define a new file system device. Valid options are:
fsdriver
This option specifies the fs driver backend to use. Currently "local", "handle" and "proxy" file system drivers are supported.
id=id
Specifies identifier for this device
path=path
Specifies the export path for the file system device. Files underthis path will be available to the 9p client on the guest.
security_model=security_model
Specifies the security model to be used for this export path. Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none". In "passthrough" security model, files are stored using the samecredentials as they are created on the guest. This requires QEMUto run as root. In "mapped-xattr" security model, some of the fileattributes like uid, gid, mode bits and link target are stored asfile attributes. For "mapped-file" these attributes are stored in thehidden .virtfs_metadata directory. Directories exported by this security model cannotinteract with other unix tools. "none" security model is same aspassthrough except the sever won't report failures if it fails toset file attributes like ownership. Security model is mandatoryonly for local fsdriver. Other fsdrivers (like handle, proxy) don't takesecurity model as a parameter.
writeout=writeout
This is an optional argument. The only supported value is "immediate". This means that host page cache will be used to read and write data butwrite notification will be sent to the guest only when the data has beenreported as written by the storage subsystem.
readonly
Enables exporting 9p share as a readonly mount for guests. By defaultread-write access is given.
socket=socket
Enables proxy filesystem driver to use passed socket file for communicatingwith virtfs-proxy-helper
sock_fd=sock_fd
Enables proxy filesystem driver to use passed socket descriptor forcommunicating with virtfs-proxy-helper. Usually a helper like libvirtwill create socketpair and pass one of the fds as sock_fd

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

-device virtio-9p-pci,fsdev=id,mount_tag=mount_tag
Options for virtio-9p-pci driver are:
fsdev=id
Specifies the id value specified along with -fsdev option
mount_tag=mount_tag
Specifies the tag name to be used by the guest to mount this export point

Virtual File system pass-through options:

-virtfs fsdriver[,path=path],mount_tag=mount_tag[,security_model=security_model][,writeout=writeout][,readonly][,socket=socket|sock_fd=sock_fd]
The general form of a Virtual File system pass-through options are:
fsdriver
This option specifies the fs driver backend to use. Currently "local", "handle" and "proxy" file system drivers are supported.
id=id
Specifies identifier for this device
path=path
Specifies the export path for the file system device. Files underthis path will be available to the 9p client on the guest.
security_model=security_model
Specifies the security model to be used for this export path. Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none". In "passthrough" security model, files are stored using the samecredentials as they are created on the guest. This requires QEMUto run as root. In "mapped-xattr" security model, some of the fileattributes like uid, gid, mode bits and link target are stored asfile attributes. For "mapped-file" these attributes are stored in thehidden .virtfs_metadata directory. Directories exported by this security model cannotinteract with other unix tools. "none" security model is same aspassthrough except the sever won't report failures if it fails toset file attributes like ownership. Security model is mandatory onlyfor local fsdriver. Other fsdrivers (like handle, proxy) don't take securitymodel as a parameter.
writeout=writeout
This is an optional argument. The only supported value is "immediate". This means that host page cache will be used to read and write data butwrite notification will be sent to the guest only when the data has beenreported as written by the storage subsystem.
readonly
Enables exporting 9p share as a readonly mount for guests. By defaultread-write access is given.
socket=socket
Enables proxy filesystem driver to use passed socket file forcommunicating with virtfs-proxy-helper. Usually a helper like libvirtwill create socketpair and pass one of the fds as sock_fd
sock_fd
Enables proxy filesystem driver to use passed 'sock_fd' as the socketdescriptor for interfacing with virtfs-proxy-helper

-virtfs_synth
Create synthetic file system image
-name name
Sets the name of the guest. This name will be displayed in the SDL window caption. The name will also be used for the VNC server. Also optionally set the top visible process name in Linux.
-uuid uuid
Set system UUID.

Display options:

-display type
Select type of display to use. This option is a replacement for theold style -sdl/-curses/... options. Valid values for type are
sdl
Display video output via SDL (usually in a separate graphicswindow; see the SDL documentation for other possibilities).
curses
Display video output via curses. For graphics device models whichsupport a text mode, QEMU can display this output using acurses/ncurses interface. Nothing is displayed when the graphicsdevice is in graphical mode or if the graphics device does not supporta text mode. Generally only the VGA device models support text mode.
none
Do not display video output. The guest will still see an emulatedgraphics card, but its output will not be displayed to the QEMUuser. This option differs from the -nographic option in that itonly affects what is done with video output; -nographic also changesthe destination of the serial and parallel port data.
vnc
Start a VNC server on display <arg>

-nographic
Normally, QEMU uses SDL to display the VGA output. With this option,you can totally disable graphical output so that QEMU is a simplecommand line application. The emulated serial port is redirected onthe console. Therefore, you can still use QEMU to debug a Linux kernelwith a serial console.
-curses
Normally, QEMU uses SDL to display the VGA output. With this option,QEMU can display the VGA output when in text mode using acurses/ncurses interface. Nothing is displayed in graphical mode.
-no-frame
Do not use decorations for SDL windows and start them using the wholeavailable screen space. This makes the using QEMU in a dedicated desktopworkspace more convenient.
-alt-grab
Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that this alsoaffects the special keys (for fullscreen, monitor-mode switching, etc).
-ctrl-grab
Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this alsoaffects the special keys (for fullscreen, monitor-mode switching, etc).
-no-quit
Disable SDL window close capability.
-sdl
Enable SDL.
-spice option[,option[,...]]
Enable the spice remote desktop protocol. Valid options are
port=<nr>
Set the TCP port spice is listening on for plaintext channels.
addr=<addr>
Set the IP address spice is listening on. Default is any address.
ipv4
ipv6
Force using the specified IP version.
password=<secret>
Set the password you need to authenticate.
sasl
Require that the client use SASL to authenticate with the spice. The exact choice of authentication method used is controlled from thesystem / user's SASL configuration file for the 'qemu' service. Thisis typically found in /etc/sasl2/qemu.conf. If running QEMU as anunprivileged user, an environment variable SASL_CONF_PATH can be usedto 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. Thisensures a data encryption preventing compromise of authenticationcredentials.
disable-ticketing
Allow client connects without authentication.
disable-copy-paste
Disable copy paste between the client and the guest.
tls-port=<nr>
Set the TCP port spice is listening on for encrypted channels.
x509-dir=<dir>
Set the x509 file directory. Expects same filenames as -vnc $display,x509=$dir
x509-key-file=<file>
x509-key-password=<file>
x509-cert-file=<file>
x509-cacert-file=<file>
x509-dh-key-file=<file>
The x509 file names can also be configured individually.
tls-ciphers=<list>
Specify which ciphers to use.
tls-channel=[main|display|cursor|inputs|record|playback]
plaintext-channel=[main|display|cursor|inputs|record|playback]
Force specific channel to be used with or without TLS encryption. Theoptions can be specified multiple times to configure multiplechannels. The special name "default" can be used to set the defaultmode. For channels which are not explicitly forced into one mode thespice client is allowed to pick tls/plaintext as he pleases.
image-compression=[auto_glz|auto_lz|quic|glz|lz|off]
Configure image compression (lossless). Default is auto_glz.
jpeg-wan-compression=[auto|never|always]
zlib-glz-wan-compression=[auto|never|always]
Configure wan image compression (lossy for slow links). Default is auto.
streaming-video=[off|all|filter]
Configure video stream detection. Default is filter.
agent-mouse=[on|off]
Enable/disable passing mouse events via vdagent. Default is on.
playback-compression=[on|off]
Enable/disable audio stream compression (using celt 0.5.1). Default is on.

-portrait
Rotate graphical output 90 deg left (only PXA LCD).
-rotate
Rotate graphical output some deg left (only PXA LCD).
-vga type
Select type of VGA card to emulate. Valid values for type are
cirrus
Cirrus Logic GD5446 Video card. All Windows versions starting fromWindows 95 should recognize and use this graphic card. For optimalperformances, use 16 bit color depth in the guest and the host OS. (This one is the default)
std
Standard VGA card with Bochs VBE extensions. If your guest OSsupports the VESA 2.0 VBE extensions (e.g. Windows XP) and if you wantto use high resolution modes (>= 1280x1024x16) then you should usethis option.
vmware
VMWare SVGA-II compatible adapter. Use it if you have sufficientlyrecent XFree86/XOrg server or Windows guest with a driver for thiscard.
qxl
QXL paravirtual graphic card. It is VGA compatible (including VESA2.0 VBE support). Works best with qxl guest drivers installed though. Recommended choice when using the spice protocol.
none
Disable VGA card.

-full-screen
Start in full screen.
-g widthxheight[xdepth]
Set the initial graphical resolution and depth (PPC, SPARC only).
-vnc display[,option[,option[,...]]]
Normally, QEMU uses SDL to display the VGA output. With this option,you can have QEMU listen on VNC display display and redirect the VGAdisplay over the VNC session. It is very useful to enable the usbtablet device when using this option (option -usbdevicetablet). When using the VNC display, you must use the -kparameter to set the keyboard layout if you are not using en-us. Validsyntax for the display is
host:d
TCP connections will only be allowed from host on display d. By convention the TCP port is 5900+ d. Optionally, host canbe omitted in which case the server will accept connections from any host.
unix:path
Connections will be allowed over UNIX domain sockets where path is thelocation of a unix socket to listen for connections on.
none
VNC is initialized but not started. The monitor change commandcan be used to later start the VNC server.

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

reverse
Connect to a listening VNC client via a “reverse” connection. Theclient is specified by the display. For reverse networkconnections ( host: d, reverse), the d argumentis a TCP port number, not a display number.
password
Require that password based authentication is used for client connections. The password must be set separately using the change command in the pcsys_monitor
tls
Require that client use TLS when communicating with the VNC server. Thisuses anonymous TLS credentials so is susceptible to a man-in-the-middleattack. It is recommended that this option be combined with either the x509 or x509verify options.
x509=/path/to/certificate/dir
Valid if tls is specified. Require that x509 credentials are usedfor negotiating the TLS session. The server will send its x509 certificateto the client. It is recommended that a password be set on the VNC serverto provide authentication of the client when this is used. The path followingthis option specifies where the x509 certificates are to be loaded from. See the vnc_security section for details on generating certificates.
x509verify=/path/to/certificate/dir
Valid if tls is specified. Require that x509 credentials are usedfor negotiating the TLS session. The server will send its x509 certificateto 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 istrusted, this is a sufficient authentication mechanism. You may still wishto set a password on the VNC server as a second authentication layer. Thepath following this option specifies where the x509 certificates are tobe loaded from. See the vnc_security section for details on generatingcertificates.
sasl
Require that the client use SASL to authenticate with the VNC server. The exact choice of authentication method used is controlled from thesystem / user's SASL configuration file for the 'qemu' service. Thisis typically found in /etc/sasl2/qemu.conf. If running QEMU as anunprivileged user, an environment variable SASL_CONF_PATH can be usedto 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. Thisensures a data encryption preventing compromise of authenticationcredentials. See the vnc_security section for details on usingSASL authentication.
acl
Turn on access control lists for checking of the x509 client certificateand SASL party. For x509 certs, the ACL check is made against thecertificate's distinguished name. This is something that looks like C=GB,O=ACME,L=Boston,CN=bob. For SASL party, the ACL check ismade against the username, which depending on the SASL plugin, mayinclude a realm component, eg bob or bob@EXAMPLE.COM. When the acl flag is set, the initial access list will beempty, with a deny policy. Thus no one will be allowed touse the VNC server until the ACLs have been loaded. This can beachieved using the acl monitor command.
lossy
Enable lossy compression methods (gradient, JPEG, ...). If thisoption is set, VNC client may receive lossy framebuffer updatesdepending on its encoding settings. Enabling this option can savea lot of bandwidth at the expense of quality.
non-adaptive
Disable adaptive encodings. Adaptive encodings are enabled by default. An adaptive encoding will try to detect frequently updated screen regions,and send updates in these regions using a lossy encoding (like JPEG). This can be really helpful to save bandwidth when playing videos. Disablingadaptive encodings allows to restore the original static behavior of encodingslike Tight.
share=[allow-exclusive|force-shared|ignore]
Set display sharing policy. 'allow-exclusive' allows clients to askfor exclusive access. As suggested by the rfb spec this isimplemented by dropping other connections. Connecting multipleclients 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 disconnecteverybody else. 'ignore' completely ignores the shared flag andallows everybody connect unconditionally. Doesn't conform to the rfbspec but is traditional QEMU behavior.

i386 target only:

-win2k-hack
Use it when installing Windows 2000 to avoid a disk full bug. AfterWindows 2000 is installed, you no longer need this option (this optionslows down the IDE transfers).
-no-fd-bootchk
Disable boot signature checking for floppy disks in Bochs BIOS. It maybe needed to boot from old floppy disks. TODO: check reference to Bochs BIOS.
-no-acpi
Disable ACPI (Advanced Configuration and Power Interface) support. Useit if your guest OS complains about ACPI problems (PC target machineonly).
-no-hpet
Disable HPET support.
-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n] [,asl_compiler_id=str][,asl_compiler_rev=n][,data=file1[:file2]...]
Add ACPI table with specified header fields and context from specified files. For file=, take whole ACPI table from the specified files, including allACPI headers (possible overridden by other options). For data=, only dataportion of the table is used, all header information is specified in thecommand line.
-smbios file=binary
Load SMBIOS entry from binary file.
-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]
Specify SMBIOS type 0 fields
-smbios type=1[,manufacturer=str][,product=str] [,version=str][,serial=str][,uuid=uuid][,sku=str] [,family=str]
Specify SMBIOS type 1 fields
Network options:
-net nic[,vlan=n][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]
Create a new Network Interface Card and connect it to VLAN n ( n= 0 is the default). The NIC is an e1000 by default on the PCtarget. Optionally, the MAC address can be changed to mac, thedevice address set to addr (PCI cards only),and a name can be assigned for use in monitor commands. Optionally, for PCI cards, you can specify the number v of MSI-X vectorsthat the card should have; this option currently only affects virtio cards; set v = 0 to disable MSI-X. If no -net option is specified, a singleNIC is created. QEMU can emulate several different models of network card. Valid values for type are virtio, i82551, i82557b, i82559er, ne2k_pci, ne2k_isa, pcnet, rtl8139, e1000, smc91c111, lance and mcf_fec. Not all devices are supported on all targets. Use -net nic,model=? for a list of available devices for your target.
-net user[,option][,option][,...]
Use the user mode network stack which requires no administratorprivilege to run. Valid options are:
vlan=n
Connect user mode stack to VLAN n ( n = 0 is the default).
name=name
Assign symbolic name for use in monitor commands.
net=addr[/mask]
Set IP network address the guest will see. Optionally specify the netmask,either in the form a.b.c.d or as number of valid top-most bits. Default is10.0.2.0/24.
host=addr
Specify the guest-visible address of the host. Default is the 2nd IP in theguest network, i.e. x.x.x.2.
restrict=on|off
If this option is enabled, the guest will be isolated, i.e. it will not beable to contact the host and no guest IP packets will be routed over the hostto the outside. This option does not affect any explicitly set forwarding rules.
hostname=name
Specifies the client hostname reported by the builtin DHCP server.
dhcpstart=addr
Specify the first of the 16 IPs the built-in DHCP server can assign. Defaultis the 15th to 31st IP in the guest network, i.e. x.x.x.15 to x.x.x.31.
dns=addr
Specify the guest-visible address of the virtual nameserver. The address mustbe different from the host address. Default is the 3rd IP in the guest network,i.e. x.x.x.3.
tftp=dir
When using the user mode network stack, activate a built-in TFTPserver. The files in dir will be exposed as the root of a TFTP server. The TFTP client on the guest must be configured in binary mode (use the command bin of the Unix TFTP client).
bootfile=file
When using the user mode network stack, broadcast file as the BOOTPfilename. In conjunction with tftp, this can be used to network boota guest from a local directory.

Example (using pxelinux): 

          qemu-system-i386 -hda linux.img -boot n -net user,tftp=/path/to/tftp/files,bootfile=/pxelinux.0

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

In the guest Windows OS, the line: 

          10.0.2.4 smbserver

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

Then dir can be accessed in \smbserver\qemu.

Note that a SAMBA server must be installed on the host OS. QEMU was tested successfully with smbd versions from Red Hat 9,Fedora Core 3 and OpenSUSE 11.x.

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

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

          # 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

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

          # on the host
          qemu-system-i386 -net user,hostfwd=tcp::5555-:23 [...]
          telnet localhost 5555

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

guestfwd=[tcp]:server:port-dev
Forward guest TCP connections to the IP address server on port portto the character device dev. This option can be given multiple times.

Note: Legacy stand-alone options -tftp, -bootp, -smb and -redir are stillprocessed and applied to -net user. Mixing them with the new configurationsyntax gives undefined results. Their use for new applications is discouragedas they will be removed from future versions.

-net tap[,vlan=n][,name=name][,fd=h][,ifname=name][,script=file][,downscript=dfile][,helper=helper]
Connect the host TAP network interface name to VLAN n.

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

If running QEMU as an unprivileged user, use the network helperhelper to configure the TAP interface. The default networkhelper executable is /usr/local/libexec/qemu-bridge-helper.

fd=h can be used to specify the handle of an alreadyopened host TAP interface.

Examples: 

     #launch a QEMU instance with the default network script
     qemu-system-i386 linux.img -net nic -net tap

     #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

     #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=/usr/local/libexec/qemu-bridge-helper"

-net bridge[,vlan=n][,name=name][,br=bridge][,helper=helper]
Connect a host TAP network interface to a host bridge device.

Use the network helper helper to configure the TAP interface andattach it to the bridge. The default network helper executable is/usr/local/libexec/qemu-bridge-helper and the default bridgedevice is br0.

Examples: 

     #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

     #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

-net socket[,vlan=n][,name=name][,fd=h] [,listen=[host]:port][,connect=host:port]
Connect the VLAN n to a remote VLAN in another QEMU virtualmachine using a TCP socket connection. If listen isspecified, QEMU waits for incoming connections on port( host is optional). connect is used to connect toanother QEMU instance using the listen option. fd= hspecifies an already opened TCP socket.

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

-net socket[,vlan=n][,name=name][,fd=h][,mcast=maddr:port[,localaddr=addr]]
Create a VLAN n shared with another QEMU virtualmachines using a UDP multicast socket, effectively making a bus forevery QEMU with same multicast address maddr and port. NOTES:
  1. Several QEMU can be running on different hosts and share same bus (assumingcorrect multicast setup for these hosts).
  2. mcast support is compatible with User Mode Linux (argument ethN=mcast), seehttp://user-mode-linux.sf.net.
  3. Use fd=h to specify an already opened UDP multicast socket.

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

Example (User Mode Linux compat.): 

     # 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

Example (send packets from host's 1.2.3.4): 

     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

-net vde[,vlan=n][,name=name][,sock=socketpath] [,port=n][,group=groupname][,mode=octalmode]
Connect VLAN n to PORT n of a vde switch running on host andlistening for incoming connections on socketpath. Use GROUP groupnameand MODE octalmode to change default ownership and permissions forcommunication port. This option is only available if QEMU has been compiledwith vde support enabled.

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

-net dump[,vlan=n][,file=file][,len=len]
Dump network traffic on VLAN n to file file ( qemu-vlan0.pcap by default). At most len bytes (64k by default) per packet are stored. The file format islibpcap, so it can be analyzed with tools such as tcpdump or Wireshark.
-net none
Indicate that no network devices should be configured. It is used tooverride the default configuration ( -net nic -net user) whichis activated if no -net options are provided.

Character device options:

The general form of a character device option is:

-chardev backend ,id=id [,mux=on|off] [,options]
Backend is one of: null, socket, udp, msmouse, vc, file, pipe, console, serial, pty, stdio, braille, tty, parport, spicevmc. 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. The key sequence of <Control-a> and <c> will rotate the input focusbetween attached front-ends. Specify mux=on to enable this mode.

Options to each backend are described below.

-chardev null ,id=id
A void device. This device will not emit any data, and will drop any data itreceives. The null backend does not take any options.
-chardev socket ,id=id [TCP options or unix options] [,server] [,nowait] [,telnet]
Create a two-way stream socket, which can be either a TCP or a unix socket. Aunix socket will be created if path is specified. Behaviour isundefined if TCP options are specified for a unix socket.

server specifies that the socket shall be a listening socket.

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

telnet specifies that traffic on the socket should interpret telnetescape sequences.

TCP and unix socket options are given below:

TCP options: port=port [,host=host] [,to=to] [,ipv4] [,ipv6] [,nodelay]
host for a listening socket specifies the local address to be bound. For a connecting socket species the remote host to connect to. host isoptional for listening sockets. If not specified it defaults to 0.0.0.0.

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

to is only relevant to listening sockets. If it is specified, andport cannot be bound, QEMU will attempt to bind to subsequent ports upto and including to until it succeeds. to must be specifiedas a port number.

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

nodelay disables the Nagle algorithm.

unix options: path=path
path specifies the local path of the unix socket. path isrequired.

-chardev udp ,id=id [,host=host] ,port=port [,localaddr=localaddr] [,localport=localport] [,ipv4] [,ipv6]
Sends all traffic from the guest to a remote host over UDP.

host specifies the remote host to connect to. If not specified itdefaults to localhost.

port specifies the port on the remote host to connect to. portis required.

localaddr specifies the local address to bind to. If not specified itdefaults to 0.0.0.0.

localport specifies the local port to bind to. If not specified anyavailable local port will be used.

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

-chardev msmouse ,id=id
Forward QEMU's emulated msmouse events to the guest. msmouse does nottake any options.
-chardev vc ,id=id [[,width=width] [,height=height]] [[,cols=cols] [,rows=rows]]
Connect to a QEMU text console. vc may optionally be given a specificsize.

width and height specify the width and height respectively ofthe console, in pixels.

cols and rows specify that the console be sized to fit a textconsole with the given dimensions.

-chardev file ,id=id ,path=path
Log all traffic received from the guest to a file.

path specifies the path of the file to be opened. This file will becreated if it does not already exist, and overwritten if it does. pathis required.

-chardev pipe ,id=id ,path=path
Create a two-way connection to the guest. The behaviour differs slightly betweenWindows hosts and other hosts:

On Windows, a single duplex pipe will be created at\.pipe\path.

On other hosts, 2 pipes will be created called path.in andpath.out. Data written to path.in will bereceived by the guest. Data written by the guest can be read frompath.out. QEMU will not create these fifos, and requires them tobe present.

path forms part of the pipe path as described above. path isrequired.

-chardev console ,id=id
Send traffic from the guest to QEMU's standard output. console does nottake any options.

console is only available on Windows hosts.

-chardev serial ,id=id ,path=path
Send traffic from the guest to a serial device on the host.

serial isonly available on Windows hosts.

path specifies the name of the serial device to open.

-chardev pty ,id=id
Create a new pseudo-terminal on the host and connect to it. pty doesnot take any options.

pty is not available on Windows hosts.

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

signal controls if signals are enabled on the terminal, that includesexiting QEMU with the key sequence <Control-c>. This option is enabled bydefault, use signal=off to disable it.

stdio is not available on Windows hosts.

-chardev braille ,id=id
Connect to a local BrlAPI server. braille does not take any options.
-chardev tty ,id=id ,path=path
Connect to a local tty device.

tty is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD andDragonFlyBSD hosts.

path specifies the path to the tty. path is required.

-chardev parport ,id=id ,path=path
parport is only available on Linux, FreeBSD and DragonFlyBSD hosts.

Connect to a local parallel port.

path specifies the path to the parallel port device. path isrequired.

-chardev spicevmc ,id=id ,debug=debug, name=name
spicevmc is only available when spice support is built in.

debug debug level for spicevmc

name name of spice channel to connect to

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

Device URL Syntax:

In addition to using normal file images for the emulated storage devices,QEMU can also use networked resources such as iSCSI devices. These arespecified using a special URL syntax.

iSCSI
iSCSI support allows QEMU to access iSCSI resources directly and use asimages for the guest storage. Both disk and cdrom images are supported.

Syntax for specifying iSCSI LUNs is“iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>”

Example (without authentication): 

     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

Example (CHAP username/password via URL): 

     qemu-system-i386 -drive file=iscsi://user%password@192.0.2.1/iqn.2001-04.com.example/1

Example (CHAP username/password via environment variables): 

     LIBISCSI_CHAP_USERNAME="user" \
     LIBISCSI_CHAP_PASSWORD="password" \
     qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1

iSCSI support is an optional feature of QEMU and only available whencompiled and linked against libiscsi.

NBD
QEMU supports NBD (Network Block Devices) both using TCP protocol as wellas Unix Domain Sockets.

Syntax for specifying a NBD device using TCP“nbd:<server-ip>:<port>[:exportname=<export>]”

Syntax for specifying a NBD device using Unix Domain Sockets“nbd:unix:<domain-socket>[:exportname=<export>]”

Example for TCP 

     qemu-system-i386 --drive file=nbd:192.0.2.1:30000

Example for Unix Domain Sockets 

     qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket

Sheepdog
Sheepdog is a distributed storage system for QEMU. QEMU supports using either local sheepdog devices or remote networkeddevices.

Syntax for specifying a sheepdog device

“sheepdog:<vdiname>”

“sheepdog:<vdiname>:<snapid>”

“sheepdog:<vdiname>:<tag>”

“sheepdog:<host>:<port>:<vdiname>”

“sheepdog:<host>:<port>:<vdiname>:<snapid>”

“sheepdog:<host>:<port>:<vdiname>:<tag>”

Example 

     qemu-system-i386 --drive file=sheepdog:192.0.2.1:30000:MyVirtualMachine

See also http://http://www.osrg.net/sheepdog/.

Bluetooth(R) options:
-bt hci[...]
Defines the function of the corresponding Bluetooth HCI. -bt optionsare matched with the HCIs present in the chosen machine type. Forexample when emulating a machine with only one HCI built into it, onlythe first -bt hci[...] option is valid and defines the HCI'slogic. The Transport Layer is decided by the machine type. Currentlythe machines n800 and n810 have one HCI and all othermachines have none.

The following three types are recognized:

-bt hci,null
(default) The corresponding Bluetooth HCI assumes no internal logicand will not respond to any HCI commands or emit events.
-bt hci,host[:id]
( bluez only) The corresponding HCI passes commands / eventsto / from the physical HCI identified by the name id (default: hci0) on the computer running QEMU. Only available on bluezcapable systems like Linux.
-bt hci[,vlan=n]
Add a virtual, standard HCI that will participate in the Bluetoothscatternet n (default 0). Similarly to -netVLANs, devices inside a bluetooth network n can only communicatewith other devices in the same network (scatternet).

-bt vhci[,vlan=n]
(Linux-host only) Create a HCI in scatternet n (default 0) attachedto the host bluetooth stack instead of to the emulated target. Thisallows the host and target machines to participate in a common scatternetand communicate. Requires the Linux vhci driver installed. Canbe used as following: 
     qemu-system-i386 [...OPTIONS...] -bt hci,vlan=5 -bt vhci,vlan=5

-bt device:dev[,vlan=n]
Emulate a bluetooth device dev and place it in network n(default 0). QEMU can only emulate one type of bluetooth devicescurrently:
keyboard
Virtual wireless keyboard implementing the HIDP bluetooth profile.

Linux/Multiboot boot specific:

When using these options, you can use a given Linux or Multibootkernel without installing it in the disk image. It can be usefulfor easier testing of various kernels.

-kernel bzImage
Use bzImage as kernel image. The kernel can be either a Linux kernelor in multiboot format.
-append cmdline
Use cmdline as kernel command line
-initrd file
Use file as initial ram disk.
-initrd "file1 arg=foo,file2"
This syntax is only available with multiboot.

Use file1 and file2 as modules and pass arg=foo as parameter to thefirst module.

-dtb file
Use file as a device tree binary (dtb) image and pass it to the kernelon boot.

Debug/Expert options:

-serial dev
Redirect the virtual serial port to host character device dev. The default device is vc in graphical mode and stdio in non graphical mode.

This option can be used several times to simulate up to 4 serialports.

Use -serial none to disable all serial ports.

Available character devices are:

vc[:WxH]
Virtual console. Optionally, a width and height can be given in pixel with 
          vc:800x600

It is also possible to specify width or height in characters: 

          vc:80Cx24C

pty
[Linux only] Pseudo TTY (a new PTY is automatically allocated)
none
No device is allocated.
null
void device
/dev/XXX
[Linux only] Use host tty, e.g. /dev/ttyS0. The host serial portparameters are set according to the emulated ones.
/dev/parportN
[Linux only, parallel port only] Use host parallel port N. Currently SPP and EPP parallel port features can be used.
file:filename
Write output to filename. No character can be read.
stdio
[Unix only] standard input/output
pipe:filename
name pipe filename
COMn
[Windows only] Use host serial port n
udp:[remote_host]:remote_port[@[src_ip]:src_port]
This implements UDP Net Console. When remote_host or src_ip are not specifiedthey default to 0.0.0.0. When not using a specified src_port a random port is automatically chosen.

If you just want a simple readonly console you can use netcat ornc, by starting QEMU with: -serial udp::4555 and nc as:nc -u -l -p 4555. Any time QEMU writes something to that port itwill appear in the netconsole session.

If you plan to send characters back via netconsole or you want to stopand start QEMU a lot of times, you should have QEMU use the samesource port each time by using something like -serialudp::4555@:4556 to QEMU. Another approach is to use a patchedversion of netcat which can listen to a TCP port and send and receivecharacters via udp. If you have a patched version of netcat whichactivates telnet remote echo and single char transfer, then you canuse the following options to step up a netcat redirector to allowtelnet on port 5555 to access the QEMU port.

QEMU Options:
-serial udp::4555@:4556
netcat options:
-u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
telnet options:
localhost 5555

tcp:[host]:port[,server][,nowait][,nodelay]
The TCP Net Console has two modes of operation. It can send the serialI/O to a location or wait for a connection from a location. By defaultthe TCP Net Console is sent to host at the port. If you usethe server option QEMU will wait for a client socket applicationto connect to the port before continuing, unless the nowaitoption was specified. The nodelay option disables the Nagle bufferingalgorithm. If host is omitted, 0.0.0.0 is assumed. Onlyone TCP connection at a time is accepted. You can use telnet toconnect to the corresponding character device.
Example to send tcp console to 192.168.0.2 port 4444
-serial tcp:192.168.0.2:4444
Example to listen and wait on port 4444 for connection
-serial tcp::4444,server
Example to not wait and listen on ip 192.168.0.100 port 4444
-serial tcp:192.168.0.100:4444,server,nowait

telnet:host:port[,server][,nowait][,nodelay]
The telnet protocol is used instead of raw tcp sockets. The optionswork the same as if you had specified -serial tcp. Thedifference is that the port acts like a telnet server or client usingtelnet option negotiation. This will also allow you to send theMAGIC_SYSRQ sequence if you use a telnet that supports sending the breaksequence. Typically in unix telnet you do it with Control-] and thentype "send break" followed by pressing the enter key.
unix:path[,server][,nowait]
A unix domain socket is used instead of a tcp socket. The option works thesame as if you had specified -serial tcp except the unix domain socket path is used for connections.
mon:dev_string
This is a special option to allow the monitor to be multiplexed ontoanother serial port. The monitor is accessed with key sequence of<Control-a> and then pressing <c>. See monitor access pcsys_keys in the -nographic section for more keys. dev_string should be any one of the serial devices specifiedabove. An example to multiplex the monitor onto a telnet serverlistening on port 4444 would be:
-serial mon:telnet::4444,server,nowait


braille
Braille device. This will use BrlAPI to display the braille output on a realor fake device.
msmouse
Three button serial mouse. Configure the guest to use Microsoft protocol.

-parallel dev
Redirect the virtual parallel port to host device dev (samedevices as the serial port). On Linux hosts, /dev/parportN canbe used to use hardware devices connected on the corresponding hostparallel port.

This option can be used several times to simulate up to 3 parallelports.

Use -parallel none to disable all parallel ports.

-monitor dev
Redirect the monitor to host device dev (same devices as theserial port). The default device is vc in graphical mode and stdio innon graphical mode.
-qmp dev
Like -monitor but opens in 'control' mode.
-mon chardev=[name][,mode=readline|control][,default]
Setup monitor on chardev name.
-debugcon dev
Redirect the debug console to host device dev (same devices as theserial port). The debug console is an I/O port which is typically port0xe9; writing to that I/O port sends output to this device. The default device is vc in graphical mode and stdio innon graphical mode.
-pidfile file
Store the QEMU process PID in file. It is useful if you launch QEMUfrom a script.
-singlestep
Run the emulation in single step mode.
-S
Do not start CPU at startup (you must type 'c' in the monitor).
-gdb dev
Wait for gdb connection on device dev (see gdb_usage). Typicalconnections will likely be TCP-based, but also UDP, pseudo TTY, or evenstdio are reasonable use case. The latter is allowing to start QEMU fromwithin gdb and establish the connection via a pipe: 
     (gdb) target remote | exec qemu-system-i386 -gdb stdio ...

-s
Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234(see gdb_usage).
-d
Output log in /tmp/qemu.log
-D logfile
Output log in logfile instead of /tmp/qemu.log
-hdachs c,h,s,[,t]
Force hard disk 0 physical geometry (1 <= c <= 16383, 1 <= h <= 16, 1 <= s <= 63) and optionally force the BIOStranslation mode ( t=none, lba or auto). Usually QEMU can guessall those parameters. This option is useful for old MS-DOS diskimages.
-L path
Set the directory for the BIOS, VGA BIOS and keymaps.
-bios file
Set the filename for the BIOS.
-enable-kvm
Enable KVM full virtualization support. This option is only availableif KVM support is enabled when compiling.
-xen-domid id
Specify xen guest domain id (XEN only).
-xen-create
Create domain using xen hypercalls, bypassing xend. Warning: should not be used when xend is in use (XEN only).
-xen-attach
Attach to existing xen domain. xend will use this when starting QEMU (XEN only).
-no-reboot
Exit instead of rebooting.
-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 thedisk image.
-loadvm file
Start right away with a saved state ( loadvm in monitor)
-daemonize
Daemonize the QEMU process after initialization. QEMU will not detach fromstandard 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 havingto cope with initialization race conditions.
-option-rom file
Load the contents of file as an option ROM. This option is useful to load things like EtherBoot.
-clock method
Force the use of the given methods for timer alarm. To see what timersare available use -clock ?.
-rtc [base=utc|localtime|date][,clock=host|vm][,driftfix=none|slew]
Specify base as utc or localtime to let the RTC start at the currentUTC or local time, respectively. localtime is required for correct date inMS-DOS or Windows. To start at a specific point in time, provide date in theformat 2006-06-17T16:01:21 or 2006-06-17. The default base is UTC.

By default the RTC is driven by the host system time. This allows to use theRTC as accurate reference clock inside the guest, specifically if the hosttime 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 clockto rt instead. To even prevent it from progressing during suspension,you can set it to vm.

Enable driftfix (i386 targets only) if you experience time drift problems,specifically with Windows' ACPI HAL. This option will try to figure out howmany timer interrupts were not processed by the Windows guest and willre-inject them.

-icount [N|auto]
Enable virtual instruction counter. The virtual cpu will execute oneinstruction every 2^ N ns of virtual time. If auto is specifiedthen the virtual cpu speed will be automatically adjusted to keep virtualtime within a few seconds of real time.

Note that while this option can give deterministic behavior, it does notprovide cycle accurate emulation. Modern CPUs contain superscalar out oforder cores with complex cache hierarchies. The number of instructionsexecuted often has little or no correlation with actual performance.

-watchdog model
Create a virtual hardware watchdog device. Once enabled (by a guestaction), the watchdog must be periodically polled by an agent insidethe guest or else the guest will be restarted.

The model is the model of hardware watchdog to emulate. Choicesfor model are: ib700 (iBASE 700) which is a very simple ISAwatchdog with a single timer, or i6300esb (Intel 6300ESB I/Ocontroller hub) which is a much more featureful PCI-based dual-timerwatchdog. Choose a model for which your guest has drivers.

Use -watchdog ? to list available hardware models. Only onewatchdog can be enabled for a guest.

-watchdog-action action
The action controls what QEMU will do when the watchdog timerexpires. The default is reset (forcefully reset the guest). Other possible actions are: shutdown (attempt to gracefully shutdown the guest), poweroff (forcefully poweroff the guest), pause (pause the guest), debug (print a debug message and continue), or none (do nothing).

Note that the shutdown action requires that the guest respondsto ACPI signals, which it may not be able to do in the sort ofsituations where the watchdog would have expired, and thus-watchdog-action shutdown is not recommended for production use.

Examples:

-watchdog i6300esb -watchdog-action pause
-watchdog ib700


-echr numeric_ascii_value
Change the escape character used for switching to the monitor when usingmonitor and serial sharing. The default is 0x01 when using the -nographic option. 0x01 is equal to pressing Control-a. You can select a different character from the asciicontrol keys where 1 through 26 map to Control-a through Control-z. Forinstance you could use the either of the following to change the escapecharacter to Control-t.
-echr 0x14
-echr 20


-virtioconsole c
Set virtio console.

This option is maintained for backward compatibility.

Please use -device virtconsole for the new way of invocation.

-show-cursor
Show cursor.
-tb-size n
Set TB size.
-incoming port
Prepare for incoming migration, listen on port.
-nodefaults
Don't create default devices.
-chroot dir
Immediately before starting guest execution, chroot to the specifieddirectory. Especially useful in combination with -runas.
-runas user
Immediately before starting guest execution, drop root privileges, switchingto the specified user.
-prom-env variable=value
Set OpenBIOS nvram variable to given value (PPC, SPARC only).
-semihosting
Semihosting mode (ARM, M68K, Xtensa only).
-old-param
Old param mode (ARM only).
-readconfig file
Read device configuration from file.
-writeconfig file
Write device configuration to file.
-nodefconfig
Normally QEMU loads configuration files from sysconfdir and datadir at startup. The -nodefconfig option will prevent QEMU from loading any of those config files.
-no-user-config
The -no-user-config option makes QEMU not load any of the user-providedconfig files on sysconfdir, but won't make it skip the QEMU-provided configfiles from datadir.
-trace [events=file][,file=file]
Specify tracing options.
events=file
Immediately enable events listed in file. The file must contain one event name (as listed in the trace-events file)per line. This option is only available if QEMU has been compiled witheither simple or stderr tracing backend.
file=file
Log output traces to file.

This option is only available if QEMU has been compiled withthe simple tracing backend.

3.4 Keys

During the graphical emulation, you can use special key combinations to changemodes. The default key mappings are shown below, but if you use -alt-grabthen the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt) and if you use-ctrl-grab then the modifier is the right Ctrl key (instead of Ctrl-Alt):

<Ctrl-Alt-f>
Toggle full screen
<Ctrl-Alt-+>
Enlarge the screen. Scaling is currently disabled.
<Ctrl-Alt–>
Shrink the screen. Scaling is currently disabled.
<Ctrl-Alt-u>
Restore the screen's un-scaled dimensions
<Ctrl-Alt-n>
Switch to virtual console 'n'. Standard console mappings are:
1
Target system display
2
Monitor
3
Serial port

<Ctrl-Alt>
Toggle mouse and keyboard grab.

In the virtual consoles, you can use <Ctrl-Up>, <Ctrl-Down>,<Ctrl-PageUp> and <Ctrl-PageDown> to move in the back log.

During emulation, if you are using the -nographic option, use<Ctrl-a h> to get terminal commands:

<Ctrl-a h>

<Ctrl-a ?>
Print this help
<Ctrl-a x>
Exit emulator
<Ctrl-a s>
Save disk data back to file (if -snapshot)
<Ctrl-a t>
Toggle console timestamps
<Ctrl-a b>
Send break (magic sysrq in Linux)
<Ctrl-a c>
Switch between console and monitor
<Ctrl-a Ctrl-a>
Send Ctrl-a

3.5 QEMU Monitor

The QEMU monitor is used to give complex commands to the QEMUemulator. You can use it to:

  • Remove or insert removable media images(such as CD-ROM or floppies).
  • Freeze/unfreeze the Virtual Machine (VM) and save or restore its statefrom a disk file.
  • Inspect the VM state without an external debugger.

3.5.1 Commands

The following commands are available:

help or ? [cmd]
Show the help for all commands or just for command cmd.
commit
Commit changes to the disk images (if -snapshot is used) or backing files.
q or quit
Quit the emulator.
block_resize
Resize a block image while a guest is running. Usually requires guestaction to see the updated size. Resize to a lower size is supported,but should be used with extreme caution. Note that this command onlyresizes image files, it can not resize block devices like LVM volumes.
block_stream
Copy data from a backing file into a block device.
block_job_set_speed
Set maximum speed for a background block operation.
block_job_cancel
Stop an active block streaming operation.
eject [-f] device
Eject a removable medium (use -f to force it).
drive_del device
Remove host block device. The result is that guest generated IO is no longersubmitted against the host device underlying the disk. Once a drive hasbeen deleted, the QEMU Block layer returns -EIO which results in IOerrors in the guest for applications that are reading/writing to the device.
change device setting
Change the configuration of a device.
change diskdevice filename [format]
Change the medium for a removable disk device to point to filename. eg 
          (qemu) change ide1-cd0 /path/to/some.iso

format is optional.

change vnc display,options
Change the configuration of the VNC server. The valid syntax for displayand options are described at sec_invocation. eg 
          (qemu) change vnc localhost:1

change vnc password [password]
Change the password associated with the VNC server. If the new password is notsupplied, the monitor will prompt for it to be entered. VNC passwords are onlysignificant up to 8 letters. eg 
          (qemu) change vnc password
          Password: ********

screendump filename
Save screen into PPM image filename.
logfile filename
Output logs to filename.
trace-event
changes status of a trace event
trace-file on|off|flush
Open, close, or flush the trace file. If no argument is given, the status of the trace file is displayed.
log item1[,...]
Activate logging of the specified items to /tmp/qemu.log.
savevm [tag|id]
Create a snapshot of the whole virtual machine. If tag isprovided, it is used as human readable identifier. If there is alreadya snapshot with the same tag or ID, it is replaced. More info at vm_snapshots.
loadvm tag|id
Set the whole virtual machine to the snapshot identified by the tag tag or the unique snapshot ID id.
delvm tag|id
Delete the snapshot identified by tag or id.
singlestep [off]
Run the emulation in single step mode. If called with option off, the emulation returns to normal mode.
stop
Stop emulation.
c or cont
Resume emulation.
system_wakeup
Wakeup guest from suspend.
gdbserver [port]
Start gdbserver session (default port=1234)
x/fmt addr
Virtual memory dump starting at addr.
xp /fmt addr
Physical memory dump starting at addr.

fmt is a format which tells the command how to format thedata. Its syntax is: /{count}{format}{size}

count
is the number of items to be dumped.
format
can be x (hex), d (signed decimal), u (unsigned decimal), o (octal),c (char) or i (asm instruction).
size
can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits). On x86, h or w can be specified with the i format torespectively select 16 or 32 bit code instruction size.

Examples:

  • Dump 10 instructions at the current instruction pointer: 
              (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
  • Dump 80 16 bit values at the start of the video memory. 
              (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

p or print/fmt expr
Print expression value. Only the format part of fmt isused. Read I/O port. Write to I/O port.
sendkey keys
Send keys to the emulator. keys could be the name of thekey or # followed by the raw value in either decimal or hexadecimalformat. Use - to press several keys simultaneously. Example: 
     sendkey ctrl-alt-f1

This command is useful to send keys that your graphical user interfaceintercepts at low level, such as ctrl-alt-f1 in X Window.

system_reset
Reset the system.
system_powerdown
Power down the system (if supported).
sum addr size
Compute the checksum of a memory region.
usb_add devname
Add the USB device devname. For details of available devices see usb_devices
usb_del devname
Remove the USB device devname from the QEMU virtual USBhub. devname has the syntax bus.addr. Use the monitorcommand info usb to see the devices you can remove.
device_add config
Add device.
device_del id
Remove device id.
cpu index
Set the default CPU.
mouse_move dx dy [dz]
Move the active mouse to the specified coordinates dx dywith optional scroll axis dz.
mouse_button val
Change the active mouse button state val (1=L, 2=M, 4=R).
mouse_set index
Set which mouse device receives events at given index, indexcan be obtained with 
     info mice

wavcapture filename [frequency [bits [channels]]]
Capture audio into filename. Using sample rate frequencybits per sample bits and number of channels channels.

Defaults:

  • Sample rate = 44100 Hz - CD quality
  • Bits = 16
  • Number of channels = 2 - Stereo

stopcapture index
Stop capture with a given index, index can be obtained with 
     info capture

memsave addr size file
save to disk virtual memory dump starting at addr of size size.
pmemsave addr size file
save to disk physical memory dump starting at addr of size size.
boot_set bootdevicelist
Define new values for the boot device list. Those values will overridethe values specified on the command line through the -boot option.

The values that can be specified here depend on the machine type, but arethe same that can be specified in the -boot command line option.

nmi cpu
Inject an NMI on the given CPU (x86 only).
migrate [-d] [-b] [-i] uri
Migrate to uri (using -d to not wait for completion). -b for migration with full copy of disk-i for migration with incremental copy of disk (base image is shared)
migrate_cancel
Cancel the current VM migration.
migrate_set_speed value
Set maximum speed to value (in bytes) for migrations.
migrate_set_downtime second
Set maximum tolerated downtime (in seconds) for migration.
client_migrate_info protocol hostname port tls-port cert-subject
Set the spice/vnc connection info for the migration target. The spice/vncserver will ask the spice/vnc client to automatically reconnect using thenew parameters (if specified) once the vm migration finished successfully.
snapshot_blkdev
Snapshot device, using snapshot file as target if provided
drive_add
Add drive to PCI storage controller.
pci_add
Hot-add PCI device.
pci_del
Hot remove PCI device.
pcie_aer_inject_error
Inject PCIe AER error
host_net_add
Add host VLAN client.
host_net_remove
Remove host VLAN client.
netdev_add
Add host network device.
netdev_del
Remove host network device.
hostfwd_add
Redirect TCP or UDP connections from host to guest (requires -net user).
hostfwd_remove
Remove host-to-guest TCP or UDP redirection.
balloon value
Request VM to change its memory allocation to value (in MB).
set_link name [on|off]
Switch link name on (i.e. up) or off (i.e. down).
watchdog_action
Change watchdog action.
acl_show aclname
List all the matching rules in the access control list, and the defaultpolicy. There are currently two named access control lists, vnc.x509dname and vnc.username matching on the x509 clientcertificate distinguished name, and SASL username respectively.
acl_policy aclname allow|deny
Set the default access control list policy, used in the event thatnone of the explicit rules match. The default policy at startup isalways deny.
acl_add aclname match allow|deny [index]
Add a match rule to the access control list, allowing or denying access. The match will normally be an exact username or x509 distinguished name,but can optionally include wildcard globs. eg *@EXAMPLE.COM toallow all users in the EXAMPLE.COM kerberos realm. The match willnormally be appended to the end of the ACL, but can be insertedearlier in the list if the optional index parameter is supplied.
acl_remove aclname match
Remove the specified match rule from the access control list.
acl_reset aclname
Remove all matches from the access control list, and set the defaultpolicy back to deny.
mce cpu bank status mcgstatus addr misc
Inject an MCE on the given CPU (x86 only).
getfd fdname
If a file descriptor is passed alongside this command using the SCM_RIGHTSmechanism on unix sockets, it is stored using the name fdname forlater use by other monitor commands.
closefd fdname
Close the file descriptor previously assigned to fdname using the getfd command. This is only needed if the file descriptor was neverused by another monitor command.
block_set_io_throttle device bps bps_rd bps_wr iops iops_rd iops_wr
Change I/O throttle limits for a block drive to bps bps_rd bps_wr iops iops_rd iops_wr
block_passwd device password
Set the encrypted device device password to password
set_password [ vnc | spice ] password [ action-if-connected ]
Change spice/vnc password. Use zero to make the password stay validforever. action-if-connected specifies what should happen incase a connection is established: fail makes the password changefail. disconnect changes the password and disconnects theclient. keep changes the password and keeps the connection up. keep is the default.
expire_password [ vnc | spice ] expire-time
Specify when a password for spice/vnc becomesinvalid. expire-time accepts:
now
Invalidate password instantly.
never
Password stays valid forever.
+nsec
Password stays valid for nsec seconds starting now.
nsec
Password is invalidated at the given time. nsec are the secondspassed since 1970, i.e. unix epoch.

info subcommand
Show various information about the system state.
info version
show the version of QEMU
info network
show the various VLANs and the associated devices
info chardev
show the character devices
info block
show the block devices
info blockstats
show block device statistics
info registers
show the cpu registers
info cpus
show infos for each CPU
info history
show the command line history
info irq
show the interrupts statistics (if available)
info pic
show i8259 (PIC) state
info pci
show emulated PCI device info
info tlb
show virtual to physical memory mappings (i386, SH4, SPARC, PPC, and Xtensa only)
info mem
show the active virtual memory mappings (i386 only)
info jit
show dynamic compiler info
info numa
show NUMA information
info kvm
show KVM information
info usb
show USB devices plugged on the virtual USB hub
info usbhost
show all USB host devices
info profile
show profiling information
info capture
show information about active capturing
info snapshots
show list of VM snapshots
info status
show the current VM status (running|paused)
info pcmcia
show guest PCMCIA status
info mice
show which guest mouse is receiving events
info vnc
show the vnc server status
info name
show the current VM name
info uuid
show the current VM UUID
info cpustats
show CPU statistics
info usernet
show user network stack connection states
info migrate
show migration status
info balloon
show balloon information
info qtree
show device tree
info qdm
show qdev device model list
info roms
show roms

info trace
show contents of trace buffer
info trace-events
show available trace events and their state

3.5.2 Integer expressions

The monitor understands integers expressions for every integerargument. You can use register names to get the value of specificsCPU registers by prefixing them with $.

3.6 Disk Images

Since version 0.6.1, QEMU supports many disk image formats, includinggrowable disk images (their size increase as non empty sectors arewritten), compressed and encrypted disk images. Version 0.8.3 addedthe new qcow2 disk image format which is essential to support VMsnapshots.

3.6.1 Quick start for disk image creation

You can create a disk image with the command:

qemu-img create myimage.img mysize

where myimage.img is the disk image filename and mysize is itssize in kilobytes. You can add an M suffix to give the size inmegabytes and a G suffix for gigabytes.

See qemu_img_invocation for more information.

3.6.2 Snapshot mode

If you use the option -snapshot, all disk images areconsidered as read only. When sectors in written, they are written ina temporary file created in /tmp. You can however force thewrite back to the raw disk images by using the commit monitorcommand (or <C-a s> in the serial console).

3.6.3 VM snapshots

VM snapshots are snapshots of the complete virtual machine includingCPU state, RAM, device state and the content of all the writabledisks. In order to use VM snapshots, you must have at least one nonremovable and writable block device using the qcow2 disk imageformat. Normally this device is the first virtual hard drive.

Use the monitor command savevm to create a new VM snapshot orreplace an existing one. A human readable name can be assigned to eachsnapshot in addition to its numerical ID.

Use loadvm to restore a VM snapshot and delvm to removea VM snapshot. info snapshots lists the available snapshotswith their associated information:

(qemu) info snapshots
Snapshot devices: hda
Snapshot list (from hda):
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         start                   41M 2006-08-06 12:38:02   00:00:14.954
2                                 40M 2006-08-06 12:43:29   00:00:18.633
3         msys                    40M 2006-08-06 12:44:04   00:00:23.514

A VM snapshot is made of a VM state info (its size is shown ininfo snapshots) and a snapshot of every writable disk image. The VM state info is stored in the first qcow2 non removableand writable block device. The disk image snapshots are stored inevery disk image. The size of a snapshot in a disk image is difficultto evaluate and is not shown by info snapshots because theassociated disk sectors are shared among all the snapshots to savedisk space (otherwise each snapshot would need a full copy of all thedisk images).

When using the (unrelated) -snapshot option(disk_images_snapshot_mode), you can always make VM snapshots,but they are deleted as soon as you exit QEMU.

VM snapshots currently have the following known limitations:

  • They cannot cope with removable devices if they are removed orinserted after a snapshot is done.
  • A few device drivers still have incomplete snapshot support so theirstate is not saved or restored properly (in particular USB).

3.6.4 qemu-img Invocation

usage: qemu-img command [command options]

The following commands are supported:

check [-f fmt] filename
create [-f fmt] [-o options] filename [size]
commit [-f fmt] [-t cache] filename
convert [-c] [-p] [-f fmt] [-t cache] [-O output_fmt] [-o options] [-s snapshot_name] [-S sparse_size] filename [filename2 [...]] output_filename
info [-f fmt] filename
snapshot [-l | -a snapshot | -c snapshot | -d snapshot] filename
rebase [-f fmt] [-t cache] [-p] [-u] -b backing_file [-F backing_fmt] filename
resize filename [+ | -]size

Command parameters:

filename
is a disk image filename
fmt
is the disk image format. It is guessed automatically in most cases. See belowfor a description of the supported disk formats.
size
is the disk image size in bytes. Optional suffixes k or K(kilobyte, 1024) M (megabyte, 1024k) and G (gigabyte, 1024M)and T (terabyte, 1024G) are supported. b is ignored.
output_filename
is the destination disk image filename
output_fmt
is the destination format
options
is a comma separated list of format specific options in aname=value format. Use -o ? for an overview of the options supportedby the used format or see the format descriptions below for details.
-c
indicates that target image must be compressed (qcow format only)
-h
with or without a command shows help and lists the supported formats
-p
display progress bar (convert and rebase commands only)
-S size
indicates the consecutive number of bytes that must contain only zerosfor qemu-img to create a sparse image during conversion. This value is roundeddown to the nearest 512 bytes. You may use the common size suffixes like k for kilobytes.
-t cache
specifies the cache mode that should be used with the (destination) file. Seethe documentation of the emulator's -drive cache=... option for allowedvalues.

Parameters to snapshot subcommand:

snapshot
is the name of the snapshot to create, apply or delete
-a
applies a snapshot (revert disk to saved state)
-c
creates a snapshot
-d
deletes a snapshot
-l
lists all snapshots in the given image

Command description:

check [-f fmt] filename
Perform a consistency check on the disk image filename.

Only the formats qcow2, qed and vdi supportconsistency checks.

create [-f fmt] [-o options] filename [size]
Create the new disk image filename of size size and format fmt. Depending on the file format, you can add one or more optionsthat enable additional features of this format.

If the option backing_file is specified, then the image will recordonly the differences from backing_file. No size needs to be specified inthis case. backing_file will never be modified unless you use thecommit monitor command (or qemu-img commit).

The size can also be specified using the size option with -o,it doesn't need to be specified separately in this case.

commit [-f fmt] [-t cache] filename
Commit the changes recorded in filename in its base image.
convert [-c] [-p] [-f fmt] [-t cache] [-O output_fmt] [-o options] [-s snapshot_name] [-S sparse_size] filename [filename2 [...]] output_filename
Convert the disk image filename or a snapshot snapshot_name to disk image output_filenameusing format output_fmt. It can be optionally compressed ( -coption) or use any format specific options like encryption ( -o option).

Only the formats qcow and qcow2 support compression. Thecompression is read-only. It means that if a compressed sector isrewritten, then it is rewritten as uncompressed data.

Image conversion is also useful to get smaller image when using agrowable format such as qcow or cow: the empty sectorsare detected and suppressed from the destination image.

You can use the backing_file option to force the output image to becreated as a copy on write image of the specified base image; thebacking_file should have the same content as the input's base image,however the path, image format, etc may differ.

info [-f fmt] filename
Give information about the disk image filename. Use it inparticular to know the size reserved on disk which can be differentfrom the displayed size. If VM snapshots are stored in the disk image,they are displayed too.
snapshot [-l | -a snapshot | -c snapshot | -d snapshot ] filename
List, apply, create or delete snapshots in image filename.
rebase [-f fmt] [-t cache] [-p] [-u] -b backing_file [-F backing_fmt] filename
Changes the backing file of an image. Only the formats qcow2 and qed support changing the backing file.

The backing file is changed to backing_file and (if the image format offilename supports this) the backing file format is changed tobacking_fmt.

There are two different modes in which rebase can operate:

Safe mode
This is the default mode and performs a real rebase operation. The new backingfile may differ from the old one and qemu-img rebase will take care of keepingthe guest-visible content of filename unchanged.

In order to achieve this, any clusters that differ between backing_fileand the old backing file of filename are merged into filenamebefore actually changing the backing file.

Note that the safe mode is an expensive operation, comparable to convertingan image. It only works if the old backing file still exists.

Unsafe mode
qemu-img uses the unsafe mode if -u is specified. In this mode, only thebacking file name and format of filename is changed without any checkson the file contents. The user must take care of specifying the correct newbacking file, or the guest-visible content of the image will be corrupted.

This mode is useful for renaming or moving the backing file to somewhere else. It can be used without an accessible old backing file, i.e. you can use it tofix an image whose backing file has already been moved/renamed.


resize filename [+ | -]size
Change the disk image as if it had been created with size.

Before using this command to shrink a disk image, you MUST use file system andpartitioning tools inside the VM to reduce allocated file systems and partitionsizes accordingly. Failure to do so will result in data loss!

After using this command to grow a disk image, you must use file system andpartitioning tools inside the VM to actually begin using the new space on thedevice.

Supported image file formats:

raw
Raw disk image format (default). This format has the advantage ofbeing simple and easily exportable to all other emulators. If yourfile system supports holes (for example in ext2 or ext3 onLinux or NTFS on Windows), then only the written sectors will reservespace. Use qemu-img info to know the real size used by theimage or ls -ls on Unix/Linux.
qcow2
QEMU image format, the most versatile format. Use it to have smallerimages (useful if your filesystem does not supports holes, for exampleon Windows), optional AES encryption, zlib based compression andsupport of multiple VM snapshots.

Supported options:

backing_file
File name of a base image (see create subcommand)
backing_fmt
Image format of the base image
encryption
If this option is set to on, the image is encrypted.

Encryption uses the AES format which is very secure (128 bit keys). Usea long password (16 characters) to get maximum protection.

cluster_size
Changes the qcow2 cluster size (must be between 512 and 2M). Smaller clustersizes can improve the image file size whereas larger cluster sizes generallyprovide better performance.
preallocation
Preallocation mode (allowed values: off, metadata). An image with preallocatedmetadata is initially larger but can improve performance when the image needsto grow.

qcow
Old QEMU image format. Left for compatibility.

Supported options:

backing_file
File name of a base image (see create subcommand)
encryption
If this option is set to on, the image is encrypted.

cow
User Mode Linux Copy On Write image format. Used to be the only growableimage format in QEMU. It is supported only for compatibility withprevious versions. It does not work on win32.
vdi
VirtualBox 1.1 compatible image format.
vmdk
VMware 3 and 4 compatible image format.

Supported options:

backing_fmt
Image format of the base image
compat6
Create a VMDK version 6 image (instead of version 4)

vpc
VirtualPC compatible image format (VHD).
cloop
Linux Compressed Loop image, useful only to reuse directly compressedCD-ROM images present for example in the Knoppix CD-ROMs.

3.6.5 qemu-nbd Invocation

usage: qemu-nbd [OPTION]...  filename

Export QEMU disk image using NBD protocol.

filename
is a disk image filename
-p, --port=port
port to listen on (default ‘ 1024’)
-o, --offset=offset
offset into the image
-b, --bind=iface
interface to bind to (default ‘ 0.0.0.0’)
-k, --socket=path
Use a unix socket with path path
-r, --read-only
export read-only
-P, --partition=num
only expose partition num
-s, --snapshot
use snapshot file
-n, --nocache
disable host cache
-c, --connect=dev
connect filename to NBD device dev
-d, --disconnect
disconnect the specified device
-e, --shared=num
device can be shared by num clients (default ‘ 1’)
-t, --persistent
don't exit on the last connection
-v, --verbose
display extra debugging information
-h, --help
display this help and exit
-V, --version
output version information and exit

3.6.6 Using host drives

In addition to disk image files, QEMU can directly access hostdevices. We describe here the usage for QEMU version >= 0.8.3.

3.6.6.1 Linux

On Linux, you can directly use the host device filename instead of adisk image filename provided you have enough privileges to accessit. For example, use /dev/cdrom to access to the CDROM or/dev/fd0 for the floppy.

CD
You can specify a CDROM device even if no CDROM is loaded. QEMU hasspecific code to detect CDROM insertion or removal. CDROM ejection bythe guest OS is supported. Currently only data CDs are supported.
Floppy
You can specify a floppy device even if no floppy is loaded. Floppyremoval is currently not detected accurately (if you change floppywithout doing floppy access while the floppy is not loaded, the guestOS will think that the same floppy is loaded).
Hard disks
Hard disks can be used. Normally you must specify the whole disk( /dev/hdb instead of /dev/hdb1) so that the guest OS cansee it as a partitioned disk. WARNING: unless you know what you do, itis better to only make READ-ONLY accesses to the hard disk otherwiseyou may corrupt your host data (use the -snapshot commandline option or modify the device permissions accordingly).
3.6.6.2 Windows
CD
The preferred syntax is the drive letter (e.g. d:). Thealternate syntax \\.\d: is supported. /dev/cdrom issupported as an alias to the first CDROM drive.

Currently there is no specific code to handle removable media, so itis better to use the change or eject monitor commands tochange or eject media.

Hard disks
Hard disks can be used with the syntax: \\.\PhysicalDriveNwhere N is the drive number (0 is the first hard disk).

WARNING: unless you know what you do, it is better to only makeREAD-ONLY accesses to the hard disk otherwise you may corrupt yourhost data (use the -snapshot command line so that themodifications are written in a temporary file).

3.6.6.3 Mac OS X

/dev/cdrom is an alias to the first CDROM.

Currently there is no specific code to handle removable media, so itis better to use the change or eject monitor commands tochange or eject media.

3.6.7 Virtual FAT disk images

QEMU can automatically create a virtual FAT disk image from adirectory tree. In order to use it, just type:

qemu-system-i386 linux.img -hdb fat:/my_directory

Then you access access to all the files in the /my_directorydirectory without having to copy them in a disk image or to exportthem via SAMBA or NFS. The default access is read-only.

Floppies can be emulated with the :floppy: option:

qemu-system-i386 linux.img -fda fat:floppy:/my_directory

A read/write support is available for testing (beta stage) with the:rw: option:

qemu-system-i386 linux.img -fda fat:floppy:rw:/my_directory

What you should never do:

  • use non-ASCII filenames ;
  • use "-snapshot" together with ":rw:" ;
  • expect it to work when loadvm'ing ;
  • write to the FAT directory on the host system while accessing it with the guest system.

3.6.8 NBD access

QEMU can access directly to block device exported using the Network Block Deviceprotocol.

qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024

If the NBD server is located on the same host, you can use an unix socket insteadof an inet socket:

qemu-system-i386 linux.img -hdb nbd:unix:/tmp/my_socket

In this case, the block device must be exported using qemu-nbd:

qemu-nbd --socket=/tmp/my_socket my_disk.qcow2

The use of qemu-nbd allows to share a disk between several guests:

qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2

and then you can use it with two guests:

qemu-system-i386 linux1.img -hdb nbd:unix:/tmp/my_socket
qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket

If the nbd-server uses named exports (since NBD 2.9.18), you must use the"exportname" option:

qemu-system-i386 -cdrom nbd:localhost:exportname=debian-500-ppc-netinst
qemu-system-i386 -cdrom nbd:localhost:exportname=openSUSE-11.1-ppc-netinst

3.6.9 Sheepdog disk images

Sheepdog is a distributed storage system for QEMU. It provides highlyavailable block level storage volumes that can be attached toQEMU-based virtual machines.

You can create a Sheepdog disk image with the command:

qemu-img create sheepdog:image size

where image is the Sheepdog image name and size is itssize.

To import the existing filename to Sheepdog, you can use aconvert command.

qemu-img convert filename sheepdog:image

You can boot from the Sheepdog disk image with the command:

qemu-system-i386 sheepdog:image

You can also create a snapshot of the Sheepdog image like qcow2.

qemu-img snapshot -c tag sheepdog:image

where tag is a tag name of the newly created snapshot.

To boot from the Sheepdog snapshot, specify the tag name of thesnapshot.

qemu-system-i386 sheepdog:image:tag

You can create a cloned image from the existing snapshot.

qemu-img create -b sheepdog:base:tag sheepdog:image

where base is a image name of the source snapshot and tagis its tag name.

If the Sheepdog daemon doesn't run on the local host, you need tospecify one of the Sheepdog servers to connect to.

qemu-img create sheepdog:hostname:port:image size
qemu-system-i386 sheepdog:hostname:port:image

3.6.10 iSCSI LUNs

iSCSI is a popular protocol used to access SCSI devices across a computernetwork.

There are two different ways iSCSI devices can be used by QEMU.

The first method is to mount the iSCSI LUN on the host, and make it appear asany other ordinary SCSI device on the host and then to access this device as a/dev/sd device from QEMU. How to do this differs between host OSes.

The second method involves using the iSCSI initiator that is built intoQEMU. This provides a mechanism that works the same way regardless of whichhost OS you are running QEMU on. This section will describe this second methodof using iSCSI together with QEMU.

In QEMU, iSCSI devices are described using special iSCSI URLs

URL syntax:
iscsi://[<username>[%<password>]@]<host>[:<port>]/<target-iqn-name>/<lun>

Username and password are optional and only used if your target is set upusing CHAP authentication for access control. Alternatively the username and password can also be set via environmentvariables to have these not show up in the process list

export LIBISCSI_CHAP_USERNAME=<username>
export LIBISCSI_CHAP_PASSWORD=<password>
iscsi://<host>/<target-iqn-name>/<lun>

Various session related parameters can be set via special options, eitherin a configuration file provided via '-readconfig' or directly on thecommand line.

Setting a specific initiator name to use when logging in to the target
-iscsi initiator-name=iqn.qemu.test:my-initiator

Controlling which type of header digest to negotiate with the target
-iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE

These can also be set via a configuration file

[iscsi]
  user = "CHAP username"
  password = "CHAP password"
  initiator-name = "iqn.qemu.test:my-initiator"
  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
  header-digest = "CRC32C"

Setting the target name allows different options for different targets

[iscsi "iqn.target.name"]
  user = "CHAP username"
  password = "CHAP password"
  initiator-name = "iqn.qemu.test:my-initiator"
  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
  header-digest = "CRC32C"

Howto use a configuration file to set iSCSI configuration options:

cat >iscsi.conf <<EOF
[iscsi]
  user = "me"
  password = "my password"
  initiator-name = "iqn.qemu.test:my-initiator"
  header-digest = "CRC32C"
EOF

qemu-system-i386 -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
    -readconfig iscsi.conf

Howto set up a simple iSCSI target on loopback and accessing it via QEMU:

This example shows how to set up an iSCSI target with one CDROM and one DISK
using the Linux STGT software target. This target is available on Red Hat based
systems as the package 'scsi-target-utils'.

tgtd --iscsi portal=127.0.0.1:3260
tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \
    -b /IMAGES/disk.img --device-type=disk
tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \
    -b /IMAGES/cd.iso --device-type=cd
tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL

qemu-system-i386 -iscsi initiator-name=iqn.qemu.test:my-initiator \
    -boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
    -cdrom iscsi://127.0.0.1/iqn.qemu.test/2

3.7 Network emulation

QEMU can simulate several network cards (PCI or ISA cards on the PCtarget) and can connect them to an arbitrary number of Virtual LocalArea Networks (VLANs). Host TAP devices can be connected to any QEMUVLAN. VLAN can be connected between separate instances of QEMU tosimulate large networks. For simpler usage, a non privileged user modenetwork stack can replace the TAP device to have a basic networkconnection.

3.7.1 VLANs

QEMU simulates several VLANs. A VLAN can be symbolised as a virtualconnection between several network devices. These devices can be forexample QEMU virtual Ethernet cards or virtual Host ethernet devices(TAP devices).

3.7.2 Using TAP network interfaces

This is the standard way to connect QEMU to a real network. QEMU addsa virtual network device on your host (called tapN), and youcan then configure it as if it was a real ethernet card.

3.7.2.1 Linux host

As an example, you can download the linux-test-xxx.tar.gzarchive and copy the script qemu-ifup in /etc andconfigure properly sudo so that the command ifconfigcontained in qemu-ifup can be executed as root. You must verifythat your host kernel supports the TAP network interfaces: thedevice /dev/net/tun must be present.

See sec_invocation to have examples of command lines using theTAP network interfaces.

3.7.2.2 Windows host

There is a virtual ethernet driver for Windows 2000/XP systems, calledTAP-Win32. But it is not included in standard QEMU for Windows,so you will need to get it separately. It is part of OpenVPN package,so download OpenVPN from : http://openvpn.net/.

3.7.3 Using the user mode network stack

By using the option -net user (default configuration if no-net option is specified), QEMU uses a completely user modenetwork stack (you don't need root privilege to use the virtualnetwork). The virtual network configuration is the following:

         QEMU VLAN      <------>  Firewall/DHCP server <-----> Internet
                           |          (10.0.2.2)
                           |
                           ---->  DNS server (10.0.2.3)
                           |
                           ---->  SMB server (10.0.2.4)

The QEMU VM behaves as if it was behind a firewall which blocks allincoming connections. You can use a DHCP client to automaticallyconfigure the network in the QEMU VM. The DHCP server assign addressesto the hosts starting from 10.0.2.15.

In order to check that the user mode network is working, you can pingthe address 10.0.2.2 and verify that you got an address in the range10.0.2.x from the QEMU virtual DHCP server.

Note that ping is not supported reliably to the internet as itwould require root privileges. It means you can only ping the localrouter (10.0.2.2).

When using the built-in TFTP server, the router is also the TFTPserver.

When using the -redir option, TCP or UDP connections can beredirected from the host to the guest. It allows for example toredirect X11, telnet or SSH connections.

3.7.4 Connecting VLANs between QEMU instances

Using the -net socket option, it is possible to make VLANsthat span several QEMU instances. See sec_invocation to have abasic example.

3.8 Other Devices

3.8.1 Inter-VM Shared Memory device

With KVM enabled on a Linux host, a shared memory device is available. Guestsmap a POSIX shared memory region into the guest as a PCI device that enableszero-copy communication to the application level of the guests. The basicsyntax is:

qemu-system-i386 -device ivshmem,size=<size in format accepted by -m>[,shm=<shm name>]

If desired, interrupts can be sent between guest VMs accessing the same sharedmemory region. Interrupt support requires using a shared memory server andusing a chardev socket to connect to it. The code for the shared memory serveris qemu.git/contrib/ivshmem-server. An example syntax when using the sharedmemory server is:

qemu-system-i386 -device ivshmem,size=<size in format accepted by -m>[,chardev=<id>]
                 [,msi=on][,ioeventfd=on][,vectors=n][,role=peer|master]
qemu-system-i386 -chardev socket,path=<path>,id=<id>

When using the server, the guest will be assigned a VM ID (>=0) that allows guestsusing the same server to communicate via interrupts. Guests can read theirVM ID from a device register (see example code). Since receiving the sharedmemory region from the server is asynchronous, there is a (small) chance theguest may boot before the shared memory is attached. To allow an applicationto ensure shared memory is attached, the VM ID register will return -1 (aninvalid VM ID) until the memory is attached. Once the shared memory isattached, the VM ID will return the guest's valid VM ID. With these semantics,the guest application can check to ensure the shared memory is attached to theguest before proceeding.

The role argument can be set to either master or peer and will affecthow the shared memory is migrated. With role=master, the guest willcopy the shared memory on migration to the destination host. Withrole=peer, the guest will not be able to migrate with the device attached. With the peer case, the device should be detached and then reattachedafter migration using the PCI hotplug support.

3.9 Direct Linux Boot

This section explains how to launch a Linux kernel inside QEMU withouthaving to make a full bootable image. It is very useful for fast Linuxkernel testing.

The syntax is:

qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"

Use -kernel to provide the Linux kernel image and-append to give the kernel command line arguments. The-initrd option can be used to provide an INITRD image.

When using the direct Linux boot, a disk image for the first hard diskhda is required because its boot sector is used to launch theLinux kernel.

If you do not need graphical output, you can disable it and redirectthe virtual serial port and the QEMU monitor to the console with the-nographic option. The typical command line is:

qemu-system-i386 -kernel arch/i386/boot/bzImage -hda root-2.4.20.img \
                 -append "root=/dev/hda console=ttyS0" -nographic

Use <Ctrl-a c> to switch between the serial console and themonitor (see pcsys_keys).

3.10 USB emulation

QEMU emulates a PCI UHCI USB controller. You can virtually plugvirtual USB devices or real host USB devices (experimental, works onlyon Linux hosts). QEMU will automatically create and connect virtual USB hubsas necessary to connect multiple USB devices.

3.10.1 Connecting USB devices

USB devices can be connected with the -usbdevice commandline optionor the usb_add monitor command. Available devices are:

mouse
Virtual Mouse. This will override the PS/2 mouse emulation when activated.
tablet
Pointer device that uses absolute coordinates (like a touchscreen). This means QEMU is able to report the mouse position without havingto grab the mouse. Also overrides the PS/2 mouse emulation when activated.
disk: file
Mass storage device based on file (see disk_images)
host: bus.addr
Pass through the host device identified by bus.addr(Linux only)
host: vendor_id:product_id
Pass through the host device identified by vendor_id:product_id(Linux only)
wacom-tablet
Virtual Wacom PenPartner tablet. This device is similar to the tabletabove but it can be used with the tslib library because in addition to touchcoordinates it reports touch pressure.
keyboard
Standard USB keyboard. Will override the PS/2 keyboard (if present).
serial:[vendorid= vendor_id ][,product_id= product_id ]: dev
Serial converter. This emulates an FTDI FT232BM chip connected to host characterdevice dev. The available character devices are the same as for the -serial option. The vendorid and productid options can beused to override the default 0403:6001. For instance, 
     usb_add serial:productid=FA00:tcp:192.168.0.2:4444

will connect to tcp port 4444 of ip 192.168.0.2, and plug that to the virtualserial converter, faking a Matrix Orbital LCD Display (USB ID 0403:FA00).

braille
Braille device. This will use BrlAPI to display the braille output on a realor fake device.
net: options
Network adapter that supports CDC ethernet and RNDIS protocols. optionsspecifies NIC options as with -net nic, options (see description). For instance, user-mode networking can be used with 
     qemu-system-i386 [...OPTIONS...] -net user,vlan=0 -usbdevice net:vlan=0

Currently this cannot be used in machines that support PCI NICs.

bt[: hci-type ]
Bluetooth dongle whose type is specified in the same format as withthe -bt hci option, see allowed HCI types. Ifno type is given, the HCI logic corresponds to -bt hci,vlan=0. This USB device implements the USB Transport Layer of HCI. Exampleusage: 
     qemu-system-i386 [...OPTIONS...] -usbdevice bt:hci,vlan=3 -bt device:keyboard,vlan=3

3.10.2 Using host USB devices on a Linux host

WARNING: this is an experimental feature. QEMU will slow down whenusing it. USB devices requiring real time streaming (i.e. USB VideoCameras) are not supported yet.

  1. If you use an early Linux 2.4 kernel, verify that no Linux driveris actually using the USB device. A simple way to do that is simply todisable the corresponding kernel module by renaming it from mydriver.oto mydriver.o.disabled.
  2. Verify that /proc/bus/usb is working (most Linux distributions should enable it by default). You should see something like that: 
         ls /proc/bus/usb
     001  devices  drivers
  3. Since only root can access to the USB devices directly, you can either launch QEMU as root or change the permissions of the USB devices you want to use. For testing, the following suffices: 
         chown -R myuid /proc/bus/usb
  4. Launch QEMU and do in the monitor: 
         info usbhost
       Device 1.2, speed 480 Mb/s
         Class 00: USB device 1234:5678, USB DISK

    You should see the list of the devices you can use (Never try to usehubs, it won't work).

  5. Add the device in QEMU by using: 
         usb_add host:1234:5678

    Normally the guest OS should report that a new USB device isplugged. You can use the option -usbdevice to do the same.

  6. Now you can try to use the host USB device in QEMU.

When relaunching QEMU, you may have to unplug and plug again the USBdevice to make it work again (this is a bug).

3.11 VNC security

The VNC server capability provides access to the graphical consoleof the guest VM across the network. This has a number of securityconsiderations depending on the deployment scenarios.

3.11.1 Without passwords

The simplest VNC server setup does not include any form of authentication. For this setup it is recommended to restrict it to listen on a UNIX domainsocket only. For example

qemu-system-i386 [...OPTIONS...] -vnc unix:/home/joebloggs/.qemu-myvm-vnc

This ensures that only users on local box with read/write access to thatpath can access the VNC server. To securely access the VNC server from aremote machine, a combination of netcat+ssh can be used to provide a securetunnel.

3.11.2 With passwords

The VNC protocol has limited support for password based authentication. Sincethe protocol limits passwords to 8 characters it should not be consideredto provide high security. The password can be fairly easily brute-forced bya client making repeat connections. For this reason, a VNC server using passwordauthentication should be restricted to only listen on the loopback interfaceor UNIX domain sockets. Password authentication is requested with the passwordoption, and then once QEMU is running the password is set with the monitor. Untilthe monitor is used to set the password all clients will be rejected.

qemu-system-i386 [...OPTIONS...] -vnc :1,password -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)

3.11.3 With x509 certificates

The QEMU VNC server also implements the VeNCrypt extension allowing use ofTLS for encryption of the session, and x509 certificates for authentication. The use of x509 certificates is strongly recommended, because TLS on itsown is susceptible to man-in-the-middle attacks. Basic x509 certificatesupport provides a secure session, but no authentication. This allows anyclient to connect, and provides an encrypted session.

qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509=/etc/pki/qemu -monitor stdio

In the above example /etc/pki/qemu should contain at least three files,ca-cert.pem, server-cert.pem and server-key.pem. Unprivilegedusers will want to use a private directory, for example $HOME/.pki/qemu. NB the server-key.pem file should be protected with file mode 0600 toonly be readable by the user owning it.

3.11.4 With x509 certificates and client verification

Certificates can also provide a means to authenticate the client connecting. The server will request that the client provide a certificate, which it willthen validate against the CA certificate. This is a good choice if deployingin an environment with a private internal certificate authority.

qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509verify=/etc/pki/qemu -monitor stdio

3.11.5 With x509 certificates, client verification and passwords

Finally, the previous method can be combined with VNC password authenticationto provide two layers of authentication for clients.

qemu-system-i386 [...OPTIONS...] -vnc :1,password,tls,x509verify=/etc/pki/qemu -monitor stdio
(qemu) change vnc password
Password: ********
(qemu)

3.11.6 With SASL authentication

The SASL authentication method is a VNC extension, that provides aneasily extendable, pluggable authentication method. This allows forintegration with a wide range of authentication mechanisms, such asPAM, GSSAPI/Kerberos, LDAP, SQL databases, one-time keys and more. The strength of the authentication depends on the exact mechanismconfigured. If the chosen mechanism also provides a SSF layer, thenit will encrypt the datastream as well.

Refer to the later docs on how to choose the exact SASL mechanismused for authentication, but assuming use of one supporting SSF,then QEMU can be launched with:

qemu-system-i386 [...OPTIONS...] -vnc :1,sasl -monitor stdio

3.11.7 With x509 certificates and SASL authentication

If the desired SASL authentication mechanism does not supportedSSF layers, then it is strongly advised to run it in combinationwith TLS and x509 certificates. This provides securely encrypteddata stream, avoiding risk of compromising of the securitycredentials. This can be enabled, by combining the 'sasl' optionwith the aforementioned TLS + x509 options:

qemu-system-i386 [...OPTIONS...] -vnc :1,tls,x509,sasl -monitor stdio

3.11.8 Generating certificates for VNC

The GNU TLS packages provides a command called certtool which canbe used to generate certificates and keys in PEM format. At a minimum itis necessary to setup a certificate authority, and issue certificates toeach server. If using certificates for authentication, then each clientwill also need to be issued a certificate. The recommendation is for theserver to keep its certificates in either /etc/pki/qemu or forunprivileged users in $HOME/.pki/qemu.

3.11.8.1 Setup the Certificate Authority

This step only needs to be performed once per organization / organizationalunit. First the CA needs a private key. This key must be kept VERY secretand secure. If this key is compromised the entire trust chain of the certificatesissued with it is lost.

# certtool --generate-privkey > ca-key.pem

A CA needs to have a public certificate. For simplicity it can be a self-signedcertificate, or one issue by a commercial certificate issuing authority. Togenerate a self-signed certificate requires one core piece of information, thename of the organization.

# cat > ca.info <<EOF
cn = Name of your organization
ca
cert_signing_key
EOF
# certtool --generate-self-signed \
           --load-privkey ca-key.pem
           --template ca.info \
           --outfile ca-cert.pem

The ca-cert.pem file should be copied to all servers and clients wishing to utilizeTLS support in the VNC server. The ca-key.pem must not be disclosed/copied at all.

3.11.8.2 Issuing server certificates

Each server (or host) needs to be issued with a key and certificate. When connectingthe certificate is sent to the client which validates it against the CA certificate. The core piece of information for a server certificate is the hostname. This shouldbe the fully qualified hostname that the client will connect with, since the clientwill typically also verify the hostname in the certificate. On the host holding thesecure CA private key:

# cat > server.info <<EOF
organization = Name  of your organization
cn = server.foo.example.com
tls_www_server
encryption_key
signing_key
EOF
# certtool --generate-privkey > server-key.pem
# certtool --generate-certificate \
           --load-ca-certificate ca-cert.pem \
           --load-ca-privkey ca-key.pem \
           --load-privkey server server-key.pem \
           --template server.info \
           --outfile server-cert.pem

The server-key.pem and server-cert.pem files should now be securely copiedto the server for which they were generated. The server-key.pem is securitysensitive and should be kept protected with file mode 0600 to prevent disclosure.

3.11.8.3 Issuing client certificates

If the QEMU VNC server is to use the x509verify option to validate clientcertificates as its authentication mechanism, each client also needs to be issueda certificate. The client certificate contains enough metadata to uniquely identifythe client, typically organization, state, city, building, etc. On the host holdingthe secure CA private key:

# cat > client.info <<EOF
country = GB
state = London
locality = London
organiazation = Name of your organization
cn = client.foo.example.com
tls_www_client
encryption_key
signing_key
EOF
# certtool --generate-privkey > client-key.pem
# certtool --generate-certificate \
           --load-ca-certificate ca-cert.pem \
           --load-ca-privkey ca-key.pem \
           --load-privkey client-key.pem \
           --template client.info \
           --outfile client-cert.pem

The client-key.pem and client-cert.pem files should now be securelycopied to the client for which they were generated.

3.11.9 Configuring SASL mechanisms

The following documentation assumes use of the Cyrus SASL implementation on aLinux host, but the principals should apply to any other SASL impl. When SASLis enabled, the mechanism configuration will be loaded from system defaultSASL service config /etc/sasl2/qemu.conf. If running QEMU as anunprivileged user, an environment variable SASL_CONF_PATH can be usedto make it search alternate locations for the service config.

The default configuration might contain

mech_list: digest-md5
sasldb_path: /etc/qemu/passwd.db

This says to use the 'Digest MD5' mechanism, which is similar to the HTTPDigest-MD5 mechanism. The list of valid usernames & passwords is maintainedin the /etc/qemu/passwd.db file, and can be updated using the saslpasswd2command. While this mechanism is easy to configure and use, it is notconsidered secure by modern standards, so only suitable for developers /ad-hoc testing.

A more serious deployment might use Kerberos, which is done with the 'gssapi'mechanism

mech_list: gssapi
keytab: /etc/qemu/krb5.tab

For this to work the administrator of your KDC must generate a Kerberosprincipal for the server, with a name of 'qemu/somehost.example.com@EXAMPLE.COM'replacing 'somehost.example.com' with the fully qualified host name of themachine running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm.

Other configurations will be left as an exercise for the reader. It shouldbe noted that only Digest-MD5 and GSSAPI provides a SSF layer for dataencryption. For all other mechanisms, VNC should always be configured touse TLS and x509 certificates to protect security credentials from snooping.

3.12 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 agdb connection:

qemu-system-i386 -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

Then launch gdb on the 'vmlinux' executable:

> gdb vmlinux

In gdb, connect to QEMU:

(gdb) target remote localhost:1234

Then you can use gdb normally. For example, type 'c' to launch the kernel:

(gdb) c

Here are some useful tips in order to use gdb on system code:

  1. Use info reg to display all the CPU registers.
  2. Use x/10i $eip to display the code at the PC position.
  3. Use set architecture i8086 to dump 16 bit code. Then usex/10i $cs*16+$eip to dump the code at the PC position.

Advanced debugging options:

The default single stepping behavior is step with the IRQs and timer service routines off. It is set this way because when gdb executes a single step it expects to advance beyond the current instruction. With the IRQs and and timer service routines on, a single step might jump into the one of the interrupt or exception vectors instead of executing the current instruction. This means you may hit the same breakpoint a number of times before executing the instruction gdb wants to have executed. Because there are rare circumstances where you want to single step into an interrupt vector the behavior can be controlled from GDB. There are three commands you can query and set the single step behavior:

maintenance packet qqemu.sstepbits
This will display the MASK bits used to control the single stepping IE: 
     (gdb) maintenance packet qqemu.sstepbits
     sending: "qqemu.sstepbits"
     received: "ENABLE=1,NOIRQ=2,NOTIMER=4"

maintenance packet qqemu.sstep
This will display the current value of the mask used when single stepping IE: 
     (gdb) maintenance packet qqemu.sstep
     sending: "qqemu.sstep"
     received: "0x7"

maintenance packet Qqemu.sstep=HEX_VALUE
This will change the single step mask, so if wanted to enable IRQs on the single step, but not timers, you would use: 
     (gdb) maintenance packet Qqemu.sstep=0x5
     sending: "qemu.sstep=0x5"
     received: "OK"

3.13 Target OS specific information

3.13.1 Linux

To have access to SVGA graphic modes under X11, use the vesa orthe cirrus X11 driver. For optimal performances, use 16 bitcolor depth in the guest and the host OS.

When using a 2.6 guest Linux kernel, you should add the optionclock=pit on the kernel command line because the 2.6 Linuxkernels make very strict real time clock checks by default that QEMUcannot simulate exactly.

When using a 2.6 guest Linux kernel, verify that the 4G/4G patch isnot activated because QEMU is slower with this patch. The QEMUAccelerator Module is also much slower in this case. Earlier FedoraCore 3 Linux kernel (< 2.6.9-1.724_FC3) were known to incorporate thispatch by default. Newer kernels don't have it.

3.13.2 Windows

If you have a slow host, using Windows 95 is better as it gives thebest speed. Windows 2000 is also a good choice.

3.13.2.1 SVGA graphic modes support

QEMU emulates a Cirrus Logic GD5446 Videocard. All Windows versions starting from Windows 95 should recognizeand use this graphic card. For optimal performances, use 16 bit colordepth in the guest and the host OS.

If you are using Windows XP as guest OS and if you want to use highresolution modes which the Cirrus Logic BIOS does not support (i.e. >=1280x1024x16), then you should use the VESA VBE virtual graphic card(option -std-vga).

3.13.2.2 CPU usage reduction

Windows 9x does not correctly use the CPU HLTinstruction. The result is that it takes host CPU cycles even whenidle. You can install the utility fromhttp://www.user.cityline.ru/~maxamn/amnhltm.zip to solve thisproblem. Note that no such tool is needed for NT, 2000 or XP.

3.13.2.3 Windows 2000 disk full problem

Windows 2000 has a bug which gives a disk full problem during itsinstallation. When installing it, use the -win2k-hack QEMUoption to enable a specific workaround. After Windows 2000 isinstalled, you no longer need this option (this option slows down theIDE transfers).

3.13.2.4 Windows 2000 shutdown

Windows 2000 cannot automatically shutdown in QEMU although Windows 98can. It comes from the fact that Windows 2000 does not automaticallyuse the APM driver provided by the BIOS.

In order to correct that, do the following (thanks to StruanBartlett): go to the Control Panel => Add/Remove Hardware & Next =>Add/Troubleshoot a device => Add a new device & Next => No, select thehardware from a list & Next => NT Apm/Legacy Support & Next => Next(again) a few times. Now the driver is installed and Windows 2000 nowcorrectly instructs QEMU to shutdown at the appropriate moment.

3.13.2.5 Share a directory between Unix and Windows

See sec_invocation about the help of the option -smb.

3.13.2.6 Windows XP security problem

Some releases of Windows XP install correctly but give a securityerror when booting:

A problem is preventing Windows from accurately checking the
license for this computer. Error code: 0x800703e6.

The workaround is to install a service pack for XP after a boot in safemode. Then reboot, and the problem should go away. Since there is nonetwork while in safe mode, its recommended to download the fullinstallation of SP1 or SP2 and transfer that via an ISO or using thevvfat block device ("-hdb fat:directory_which_holds_the_SP").

3.13.3 MS-DOS and FreeDOS

3.13.3.1 CPU usage reduction

DOS does not correctly use the CPU HLT instruction. The result is thatit takes host CPU cycles even when idle. You can install the utilityfrom http://www.vmware.com/software/dosidle210.zip to solve thisproblem.

4 QEMU System emulator for non PC targets

QEMU is a generic emulator and it emulates many non PCmachines. Most of the options are similar to the PC emulator. Thedifferences are mentioned in the following sections.

4.1 PowerPC System emulator

Use the executable qemu-system-ppc to simulate a complete PREPor PowerMac PowerPC system.

QEMU emulates the following PowerMac peripherals:

  • UniNorth or Grackle PCI Bridge
  • PCI VGA compatible card with VESA Bochs Extensions
  • 2 PMAC IDE interfaces with hard disk and CD-ROM support
  • NE2000 PCI adapters
  • Non Volatile RAM
  • VIA-CUDA with ADB keyboard and mouse.

QEMU emulates the following PREP peripherals:

  • PCI Bridge
  • PCI VGA compatible card with VESA Bochs Extensions
  • 2 IDE interfaces with hard disk and CD-ROM support
  • Floppy disk
  • NE2000 network adapters
  • Serial port
  • PREP Non Volatile RAM
  • PC compatible keyboard and mouse.

QEMU uses the Open Hack'Ware Open Firmware Compatible BIOS available athttp://perso.magic.fr/l_indien/OpenHackWare/index.htm.

Since version 0.9.1, QEMU uses OpenBIOS http://www.openbios.org/for the g3beige and mac99 PowerMac machines. OpenBIOS is a free (GPLv2) portable firmware implementation. The goal is to implement a 100%IEEE 1275-1994 (referred to as Open Firmware) compliant firmware.

The following options are specific to the PowerPC emulation:

-g WxH[xDEPTH]
Set the initial VGA graphic mode. The default is 800x600x15.
-prom-env string
Set OpenBIOS variables in NVRAM, for example: 
     qemu-system-ppc -prom-env 'auto-boot?=false' \
      -prom-env 'boot-device=hd:2,\yaboot' \
      -prom-env 'boot-args=conf=hd:2,\yaboot.conf'

These variables are not used by Open Hack'Ware.

More information is available athttp://perso.magic.fr/l_indien/qemu-ppc/.

4.2 Sparc32 System emulator

Use the executable qemu-system-sparc to simulate the followingSun4m architecture machines:

  • SPARCstation 4
  • SPARCstation 5
  • SPARCstation 10
  • SPARCstation 20
  • SPARCserver 600MP
  • SPARCstation LX
  • SPARCstation Voyager
  • SPARCclassic
  • SPARCbook

The emulation is somewhat complete. SMP up to 16 CPUs is supported,but Linux limits the number of usable CPUs to 4.

It's also possible to simulate a SPARCstation 2 (sun4c architecture),SPARCserver 1000, or SPARCcenter 2000 (sun4d architecture), but theseemulators are not usable yet.

QEMU emulates the following sun4m/sun4c/sun4d peripherals:

  • IOMMU or IO-UNITs
  • TCX Frame buffer
  • Lance (Am7990) Ethernet
  • Non Volatile RAM M48T02/M48T08
  • Slave I/O: timers, interrupt controllers, Zilog serial ports, keyboardand power/reset logic
  • ESP SCSI controller with hard disk and CD-ROM support
  • Floppy drive (not on SS-600MP)
  • CS4231 sound device (only on SS-5, not working yet)

The number of peripherals is fixed in the architecture. Maximummemory size depends on the machine type, for SS-5 it is 256MB and forothers 2047MB.

Since version 0.8.2, QEMU uses OpenBIOShttp://www.openbios.org/. OpenBIOS is a free (GPL v2) portablefirmware implementation. The goal is to implement a 100% IEEE1275-1994 (referred to as Open Firmware) compliant firmware.

A sample Linux 2.6 series kernel and ram disk image are available onthe QEMU web site. There are still issues with NetBSD and OpenBSD, butsome kernel versions work. Please note that currently Solaris kernelsdon't work probably due to interface issues between OpenBIOS andSolaris.

The following options are specific to the Sparc32 emulation:

-g WxHx[xDEPTH]
Set the initial TCX graphic mode. The default is 1024x768x8, currentlythe only other possible mode is 1024x768x24.
-prom-env string
Set OpenBIOS variables in NVRAM, for example: 
     qemu-system-sparc -prom-env 'auto-boot?=false' \
      -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'

-M [SS-4|SS-5|SS-10|SS-20|SS-600MP|LX|Voyager|SPARCClassic] [|SPARCbook|SS-2|SS-1000|SS-2000]
Set the emulated machine type. Default is SS-5.

4.3 Sparc64 System emulator

Use the executable qemu-system-sparc64 to simulate a Sun4u(UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or genericNiagara (T1) machine. The emulator is not usable for anything yet, butit can launch some kernels.

QEMU emulates the following peripherals:

  • UltraSparc IIi APB PCI Bridge
  • PCI VGA compatible card with VESA Bochs Extensions
  • PS/2 mouse and keyboard
  • Non Volatile RAM M48T59
  • PC-compatible serial ports
  • 2 PCI IDE interfaces with hard disk and CD-ROM support
  • Floppy disk

The following options are specific to the Sparc64 emulation:

-prom-env string
Set OpenBIOS variables in NVRAM, for example: 
     qemu-system-sparc64 -prom-env 'auto-boot?=false'

-M [sun4u|sun4v|Niagara]
Set the emulated machine type. The default is sun4u.

4.4 MIPS System emulator

Four executables cover simulation of 32 and 64-bit MIPS systems inboth endian options, qemu-system-mips, qemu-system-mipselqemu-system-mips64 and qemu-system-mips64el. Five different machine types are emulated:

  • A generic ISA PC-like machine "mips"
  • The MIPS Malta prototype board "malta"
  • An ACER Pica "pica61". This machine needs the 64-bit emulator.
  • MIPS emulator pseudo board "mipssim"
  • A MIPS Magnum R4000 machine "magnum". This machine needs the 64-bit emulator.

The generic emulation is supported by Debian 'Etch' and is able toinstall Debian into a virtual disk image. The following devices areemulated:

  • A range of MIPS CPUs, default is the 24Kf
  • PC style serial port
  • PC style IDE disk
  • NE2000 network card

The Malta emulation supports the following devices:

  • Core board with MIPS 24Kf CPU and Galileo system controller
  • PIIX4 PCI/USB/SMbus controller
  • The Multi-I/O chip's serial device
  • PCI network cards (PCnet32 and others)
  • Malta FPGA serial device
  • Cirrus (default) or any other PCI VGA graphics card

The ACER Pica emulation supports:

  • MIPS R4000 CPU
  • PC-style IRQ and DMA controllers
  • PC Keyboard
  • IDE controller

The mipssim pseudo board emulation provides an environment similarto what the proprietary MIPS emulator uses for running Linux. It supports:

  • A range of MIPS CPUs, default is the 24Kf
  • PC style serial port
  • MIPSnet network emulation

The MIPS Magnum R4000 emulation supports:

  • MIPS R4000 CPU
  • PC-style IRQ controller
  • PC Keyboard
  • SCSI controller
  • G364 framebuffer

4.5 ARM System emulator

Use the executable qemu-system-arm to simulate a ARMmachine. The ARM Integrator/CP board is emulated with the followingdevices:

  • ARM926E, ARM1026E, ARM946E, ARM1136 or Cortex-A8 CPU
  • Two PL011 UARTs
  • SMC 91c111 Ethernet adapter
  • PL110 LCD controller
  • PL050 KMI with PS/2 keyboard and mouse.
  • PL181 MultiMedia Card Interface with SD card.

The ARM Versatile baseboard is emulated with the following devices:

  • ARM926E, ARM1136 or Cortex-A8 CPU
  • PL190 Vectored Interrupt Controller
  • Four PL011 UARTs
  • SMC 91c111 Ethernet adapter
  • PL110 LCD controller
  • PL050 KMI with PS/2 keyboard and mouse.
  • PCI host bridge. Note the emulated PCI bridge only provides access toPCI memory space. It does not provide access to PCI IO space. This means some devices (eg. ne2k_pci NIC) are not usable, and others(eg. rtl8139 NIC) are only usable when the guest drivers use the memorymapped control registers.
  • PCI OHCI USB controller.
  • LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices.
  • PL181 MultiMedia Card Interface with SD card.

Several variants of the ARM RealView baseboard are emulated,including the EB, PB-A8 and PBX-A9. Due to interactions with thebootloader, only certain Linux kernel configurations work outof the box on these boards.

Kernels for the PB-A8 board should have CONFIG_REALVIEW_HIGH_PHYS_OFFSETenabled in the kernel, and expect 512M RAM. Kernels for The PBX-A9 boardshould have CONFIG_SPARSEMEM enabled, CONFIG_REALVIEW_HIGH_PHYS_OFFSETdisabled and expect 1024M RAM.

The following devices are emulated:

  • ARM926E, ARM1136, ARM11MPCore, Cortex-A8 or Cortex-A9 MPCore CPU
  • ARM AMBA Generic/Distributed Interrupt Controller
  • Four PL011 UARTs
  • SMC 91c111 or SMSC LAN9118 Ethernet adapter
  • PL110 LCD controller
  • PL050 KMI with PS/2 keyboard and mouse
  • PCI host bridge
  • PCI OHCI USB controller
  • LSI53C895A PCI SCSI Host Bus Adapter with hard disk and CD-ROM devices
  • PL181 MultiMedia Card Interface with SD card.

The XScale-based clamshell PDA models ("Spitz", "Akita", "Borzoi"and "Terrier") emulation includes the following peripherals:

  • Intel PXA270 System-on-chip (ARM V5TE core)
  • NAND Flash memory
  • IBM/Hitachi DSCM microdrive in a PXA PCMCIA slot - not in "Akita"
  • On-chip OHCI USB controller
  • On-chip LCD controller
  • On-chip Real Time Clock
  • TI ADS7846 touchscreen controller on SSP bus
  • Maxim MAX1111 analog-digital converter on I^2C bus
  • GPIO-connected keyboard controller and LEDs
  • Secure Digital card connected to PXA MMC/SD host
  • Three on-chip UARTs
  • WM8750 audio CODEC on I^2C and I^2S busses

The Palm Tungsten|E PDA (codename "Cheetah") emulation includes thefollowing elements:

  • Texas Instruments OMAP310 System-on-chip (ARM 925T core)
  • ROM and RAM memories (ROM firmware image can be loaded with -option-rom)
  • On-chip LCD controller
  • On-chip Real Time Clock
  • TI TSC2102i touchscreen controller / analog-digital converter / AudioCODEC, connected through MicroWire and I^2S busses
  • GPIO-connected matrix keypad
  • Secure Digital card connected to OMAP MMC/SD host
  • Three on-chip UARTs

Nokia N800 and N810 internet tablets (known also as RX-34 and RX-44 / 48)emulation supports the following elements:

  • Texas Instruments OMAP2420 System-on-chip (ARM 1136 core)
  • RAM and non-volatile OneNAND Flash memories
  • Display connected to EPSON remote framebuffer chip and OMAP on-chipdisplay controller and a LS041y3 MIPI DBI-C controller
  • TI TSC2301 (in N800) and TI TSC2005 (in N810) touchscreen controllersdriven through SPI bus
  • National Semiconductor LM8323-controlled qwerty keyboard driventhrough I^2C bus
  • Secure Digital card connected to OMAP MMC/SD host
  • Three OMAP on-chip UARTs and on-chip STI debugging console
  • A Bluetooth(R) transceiver and HCI connected to an UART
  • Mentor Graphics "Inventra" dual-role USB controller embedded in a TITUSB6010 chip - only USB host mode is supported
  • TI TMP105 temperature sensor driven through I^2C bus
  • TI TWL92230C power management companion with an RTC on I^2C bus
  • Nokia RETU and TAHVO multi-purpose chips with an RTC, connectedthrough CBUS

The Luminary Micro Stellaris LM3S811EVB emulation includes the followingdevices:

  • Cortex-M3 CPU core.
  • 64k Flash and 8k SRAM.
  • Timers, UARTs, ADC and I^2C interface.
  • OSRAM Pictiva 96x16 OLED with SSD0303 controller on I^2C bus.

The Luminary Micro Stellaris LM3S6965EVB emulation includes the followingdevices:

  • Cortex-M3 CPU core.
  • 256k Flash and 64k SRAM.
  • Timers, UARTs, ADC, I^2C and SSI interfaces.
  • OSRAM Pictiva 128x64 OLED with SSD0323 controller connected via SSI.

The Freecom MusicPal internet radio emulation includes the followingelements:

  • Marvell MV88W8618 ARM core.
  • 32 MB RAM, 256 KB SRAM, 8 MB flash.
  • Up to 2 16550 UARTs
  • MV88W8xx8 Ethernet controller
  • MV88W8618 audio controller, WM8750 CODEC and mixer
  • 128×64 display with brightness control
  • 2 buttons, 2 navigation wheels with button function

The Siemens SX1 models v1 and v2 (default) basic emulation. The emulation includes the following elements:

  • Texas Instruments OMAP310 System-on-chip (ARM 925T core)
  • ROM and RAM memories (ROM firmware image can be loaded with -pflash)V11 Flash of 16MB and 1 Flash of 8MBV21 Flash of 32MB
  • On-chip LCD controller
  • On-chip Real Time Clock
  • Secure Digital card connected to OMAP MMC/SD host
  • Three on-chip UARTs

A Linux 2.6 test image is available on the QEMU web site. Moreinformation is available in the QEMU mailing-list archive.

The following options are specific to the ARM emulation:

-semihosting
Enable semihosting syscall emulation.

On ARM this implements the "Angel" interface.

Note that this allows guest direct access to the host filesystem,so should only be used with trusted guest OS.

4.6 ColdFire System emulator

Use the executable qemu-system-m68k to simulate a ColdFire machine. The emulator is able to boot a uClinux kernel.

The M5208EVB emulation includes the following devices:

  • MCF5208 ColdFire V2 Microprocessor (ISA A+ with EMAC).
  • Three Two on-chip UARTs.
  • Fast Ethernet Controller (FEC)

The AN5206 emulation includes the following devices:

  • MCF5206 ColdFire V2 Microprocessor.
  • Two on-chip UARTs.

The following options are specific to the ColdFire emulation:

-semihosting
Enable semihosting syscall emulation.

On M68K this implements the "ColdFire GDB" interface used by libgloss.

Note that this allows guest direct access to the host filesystem,so should only be used with trusted guest OS.

4.7 Cris System emulator

TODO

4.8 Microblaze System emulator

TODO

4.9 SH4 System emulator

TODO

4.10 Xtensa System emulator

Two executables cover simulation of both Xtensa endian options,qemu-system-xtensa and qemu-system-xtensaeb. Two different machine types are emulated:

  • Xtensa emulator pseudo board "sim"
  • Avnet LX60/LX110/LX200 board

The sim pseudo board emulation provides an environment similarto one provided by the proprietary Tensilica ISS. It supports:

  • A range of Xtensa CPUs, default is the DC232B
  • Console and filesystem access via semihosting calls

The Avnet LX60/LX110/LX200 emulation supports:

  • A range of Xtensa CPUs, default is the DC232B
  • 16550 UART
  • OpenCores 10/100 Mbps Ethernet MAC

The following options are specific to the Xtensa emulation:

-semihosting
Enable semihosting syscall emulation.

Xtensa semihosting provides basic file IO calls, such as open/read/write/seek/select. Tensilica baremetal libc for ISS and linux platform "sim" use this interface.

Note that this allows guest direct access to the host filesystem,so should only be used with trusted guest OS.

5 QEMU User space emulator

5.1 Supported Operating Systems

The following OS are supported in user space emulation:

  • Linux (referred as qemu-linux-user)
  • BSD (referred as qemu-bsd-user)

5.2 Linux User space emulator

5.2.1 Quick Start

In order to launch a Linux process, QEMU needs the process executableitself and all the target (x86) dynamic libraries used by it.

  • On x86, you can just try to launch any process by using the nativelibraries: 
         qemu-i386 -L / /bin/ls

    -L / tells that the x86 dynamic linker must be searched with a/ prefix.

  • Since QEMU is also a linux process, you can launch QEMU withQEMU (NOTE: you can only do that if you compiled QEMU from the sources): 
         qemu-i386 -L / qemu-i386 -L / /bin/ls
  • On non x86 CPUs, you need first to download at least an x86 glibc(qemu-runtime-i386-XXX-.tar.gz on the QEMU web page). Ensure thatLD_LIBRARY_PATH is not set: 
         unset LD_LIBRARY_PATH

    Then you can launch the precompiled ls x86 executable: 

         qemu-i386 tests/i386/ls

    You can look at scripts/qemu-binfmt-conf.sh so thatQEMU is automatically launched by the Linux kernel when you try tolaunch x86 executables. It requires the binfmt_misc module in theLinux kernel.

  • The x86 version of QEMU is also included. You can try weird things such as: 
         qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 \
               /usr/local/qemu-i386/bin/ls-i386

5.2.2 Wine launch

  • Ensure that you have a working QEMU with the x86 glibcdistribution (see previous section). In order to verify it, you must beable to do: 
         qemu-i386 /usr/local/qemu-i386/bin/ls-i386
  • Download the binary x86 Wine install(qemu-XXX-i386-wine.tar.gz on the QEMU web page).
  • Configure Wine on your account. Look at the provided script/usr/local/qemu-i386/bin/wine-conf.sh. Your previous${HOME}/.wine directory is saved to ${HOME}/.wine.org.
  • Then you can try the example putty.exe: 
         qemu-i386 /usr/local/qemu-i386/wine/bin/wine \
               /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe

5.2.3 Command line options

usage: qemu-i386 [-h] [-d] [-L path] [-s size] [-cpu model] [-g port] [-B offset] [-R size] program [arguments...]
-h
Print the help
-L path
Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
-s size
Set the x86 stack size in bytes (default=524288)
-cpu model
Select CPU model (-cpu ? for list and additional feature selection)
-ignore-environment
Start with an empty environment. Without this option,the initial environment is a copy of the caller's environment.
-E var=value
Set environment var to value.
-U var
Remove var from the environment.
-B offset
Offset guest address by the specified number of bytes. This is useful whenthe address region required by guest applications is reserved on the host. This option is currently only supported on some hosts.
-R size
Pre-allocate a guest virtual address space of the given size (in bytes). "G", "M", and "k" suffixes may be used when specifying the size.

Debug options:

-d
Activate log (logfile=/tmp/qemu.log)
-p pagesize
Act as if the host page size was 'pagesize' bytes
-g port
Wait gdb connection to port
-singlestep
Run the emulation in single step mode.

Environment variables:

QEMU_STRACE
Print system calls and arguments similar to the 'strace' program(NOTE: the actual 'strace' program will not work because the userspace emulator hasn't implemented ptrace). At the moment this isincomplete. All system calls that don't have a specific argumentformat are printed with information for six arguments. Manyflag-style arguments don't have decoders and will show up as numbers.

5.2.4 Other binaries

qemu-alpha TODO.

qemu-armeb TODO.

qemu-arm is also capable of running ARM "Angel" semihosted ELFbinaries (as implemented by the arm-elf and arm-eabi Newlib/GDBconfigurations), and arm-uclinux bFLT format binaries.

qemu-m68k is capable of running semihosted binaries using the BDM(m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, andcoldfire uClinux bFLT format binaries.

The binary format is detected automatically.

qemu-cris TODO.

qemu-i386 TODO. qemu-x86_64 TODO.

qemu-microblaze TODO.

qemu-mips TODO. qemu-mipsel TODO.

qemu-ppc64abi32 TODO. qemu-ppc64 TODO. qemu-ppc TODO.

qemu-sh4eb TODO. qemu-sh4 TODO.

qemu-sparc can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).

qemu-sparc32plus can execute Sparc32 and SPARC32PLUS binaries(Sparc64 CPU, 32 bit ABI).

qemu-sparc64 can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) andSPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).

5.3 BSD User space emulator

5.3.1 BSD Status

  • target Sparc64 on Sparc64: Some trivial programs work.

5.3.2 Quick Start

In order to launch a BSD process, QEMU needs the process executableitself and all the target dynamic libraries used by it.

  • On Sparc64, you can just try to launch any process by using the nativelibraries: 
         qemu-sparc64 /bin/ls

5.3.3 Command line options

usage: qemu-sparc64 [-h] [-d] [-L path] [-s size] [-bsd type] program [arguments...]
-h
Print the help
-L path
Set the library root path (default=/)
-s size
Set the stack size in bytes (default=524288)
-ignore-environment
Start with an empty environment. Without this option,the initial environment is a copy of the caller's environment.
-E var=value
Set environment var to value.
-U var
Remove var from the environment.
-bsd type
Set the type of the emulated BSD Operating system. Valid values areFreeBSD, NetBSD and OpenBSD (default).

Debug options:

-d
Activate log (logfile=/tmp/qemu.log)
-p pagesize
Act as if the host page size was 'pagesize' bytes
-singlestep
Run the emulation in single step mode.

6 Compilation from the sources

6.1 Linux/Unix

6.1.1 Compilation

First you must decompress the sources:

cd /tmp
tar zxvf qemu-x.y.z.tar.gz
cd qemu-x.y.z

Then you configure QEMU and build it (usually no options are needed):

./configure
make

Then type as root user:

make install

to install QEMU in /usr/local.

6.2 Windows

  • Install the current versions of MSYS and MinGW fromhttp://www.mingw.org/. You can find detailed installationinstructions in the download section and the FAQ.
  • Downloadthe MinGW development library of SDL 1.2.x(SDL-devel-1.2.x-mingw32.tar.gz) fromhttp://www.libsdl.org. Unpack it in a temporary place andedit the sdl-config script so that it gives thecorrect SDL directory when invoked.
  • Install the MinGW version of zlib and make surezlib.h and libz.dll.a are inMinGW's default header and linker search paths.
  • Extract the current version of QEMU.
  • Start the MSYS shell (file msys.bat).
  • Change to the QEMU directory. Launch ./configure andmake. If you have problems using SDL, verify thatsdl-config can be launched from the MSYS command line.
  • You can install QEMU in Program Files/QEMU by typingmake install. Don't forget to copy SDL.dll inProgram Files/QEMU.

6.3 Cross compilation for Windows with Linux

  • Install the MinGW cross compilation tools available athttp://www.mingw.org/.
  • Downloadthe MinGW development library of SDL 1.2.x(SDL-devel-1.2.x-mingw32.tar.gz) fromhttp://www.libsdl.org. Unpack it in a temporary place andedit the sdl-config script so that it gives thecorrect SDL directory when invoked. Set up the PATH environmentvariable so that sdl-config can be launched bythe QEMU configuration script.
  • Install the MinGW version of zlib and make surezlib.h and libz.dll.a are inMinGW's default header and linker search paths.
  • Configure QEMU for Windows cross compilation: 
         PATH=/usr/i686-pc-mingw32/sys-root/mingw/bin:$PATH ./configure --cross-prefix='i686-pc-mingw32-'

    The example assumes sdl-config is installed under /usr/i686-pc-mingw32/sys-root/mingw/bin andMinGW cross compilation tools have names like i686-pc-mingw32-gcc and i686-pc-mingw32-strip. We set the PATH environment variable to ensure the MinGW version of sdl-config is used anduse –cross-prefix to specify the name of the cross compiler. You can also use –prefix to set the Win32 install path which defaults to c:/Program Files/QEMU.

    Under Fedora Linux, you can run: 

         yum -y install mingw32-gcc mingw32-SDL mingw32-zlib

    to get a suitable cross compilation environment.

  • You can install QEMU in the installation directory by typingmake install. Don't forget to copy SDL.dll and zlib1.dll into theinstallation directory.

Wine can be used to launch the resulting qemu-system-i386.exeand all other qemu-system-target.exe compiled for Win32.

6.4 Mac OS X

The Mac OS X patches are not fully merged in QEMU, so you should lookat the QEMU mailing list archive to have all the necessaryinformation.

6.5 Make targets

make
make all
Make everything which is typically needed.
install
TODO
install-doc
TODO
make clean
Remove most files which were built during make.
make distclean
Remove everything which was built during make.
make dvi
make html
make info
make pdf
Create documentation in dvi, html, info or pdf format.
make cscope
TODO
make defconfig
(Re-)create some build configuration files. User made changes will be overwritten.
tar
tarbin
TODO

Appendix A License

QEMU is a trademark of Fabrice Bellard.

QEMU is released under the GNU General Public License (TODO: add link). Parts of QEMU have specific licenses, see file LICENSE.

TODO (refer to file LICENSE, include it, include the GPL?)

Appendix B Index

B.1 Concept Index

This is the main index. Should we combine all keywords in one index? TODO

B.2 Function Index

This index could be used for command line options and monitor functions.

B.3 Keystroke Index

This is a list of all keystrokes which have a special functionin system emulation.

B.4 Program Index

B.5 Data Type Index

This index could be used for qdev device names and options.

B.6 Variable Index


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