QEMU(1)QEMU(1)NAME
qemu-doc - QEMU Emulator User Documentation
SYNOPSIS
usage: qemu-system-i386 [options] [disk_image]
DESCRIPTION
The QEMU PC System emulator simulates the following peripherals:
- i440FX host PCI bridge and PIIX3 PCI to ISA bridge
- Cirrus CLGD 5446 PCI VGA card or dummy VGA card with Bochs VESA
extensions (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.
QEMU uses the PC BIOS from the Bochs project and the Plex86/Bochs LGPL
VGA 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 so
QEMU 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
OPTIONS
disk_image is a raw hard disk image for IDE hard disk 0. Some targets
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 help" to list
available 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 more than one accelerator specified,
the next one is used if the previous one fails to 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.
dump-guest-core=on|off
Include guest memory in a core dump. The default is on.
mem-merge=on|off
Enables or disables memory merge support. This feature, when
supported by the host, de-duplicates identical memory pages
among VMs instances (enabled by default).
-cpu model
Select CPU model ("-cpu help" 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 255
CPUs are supported. On Sparc32 target, Linux limits the number of
usable CPUs to 4. For the PC target, the number of cores per
socket, the number of threads per cores and the total number of
sockets can be specified. Missing values will be computed. If any
on the three values is given, the total number of CPUs n can be
omitted. maxcpus specifies the maximum number of hotpluggable CPUs.
-numa opts
Simulate a multi node NUMA system. If mem and cpus are omitted,
resources are split equally.
-add-fd fd=fd,set=set[,opaque=opaque]
Add a file descriptor to an fd set. Valid options are:
fd=fd
This option defines the file descriptor of which a duplicate is
added to fd set. The file descriptor cannot be stdin, stdout,
or stderr.
set=set
This option defines the ID of the fd set to add the file
descriptor to.
opaque=opaque
This option defines a free-form string that can be used to
describe fd.
You can open an image using pre-opened file descriptors from an fd
set:
qemu-system-i386
-add-fd fd=3,set=2,opaque="rdwr:/path/to/file"
-add-fd fd=4,set=2,opaque="rdonly:/path/to/file"
-drive file=/dev/fdset/2,index=0,media=disk
-set group.id.arg=value
Set parameter arg for item id of type group "
-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 are created automatically by the machine model. To
create a device which is not created automatically and set
properties on it, use -device.
-boot
[order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]
Specify boot order drives as a string of drive letters. Valid drive
letters depend on the target achitecture. The x86 PC uses: a, b
(floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
(Etherboot from network adapter 1-4), hard disk boot is the
default. To apply a particular boot order only on the first
startup, specify it via once.
Interactive boot menus/prompts can be enabled via menu=on as far as
firmware/BIOS supports them. The default is non-interactive boot.
A splash picture could be passed to bios, enabling user to show it
as logo, when option splash=sp_name is given and menu=on, If
firmware/BIOS supports them. Currently Seabios for X86 system
support it. limitation: The splash file could be a jpeg file or a
BMP file in 24 BPP format(true color). The resolution should be
supported by the SVGA mode, so the recommended is 320x240, 640x480,
800x640.
A timeout could be passed to bios, guest will pause for rb_timeout
ms when boot failed, then reboot. If rb_timeout is '-1', guest will
not reboot, qemu passes '-1' to bios by default. Currently Seabios
for X86 system support it.
Do strict boot via strict=on as far as firmware/BIOS supports it.
This only effects when boot priority is changed by bootindex
options. The default is non-strict boot.
# try to boot from network first, then from hard disk
qemu-system-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 its
use is discouraged as it may be removed from future versions.
-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 or gigabytes 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" for French). This
option is only needed where it is not easy to get raw PC keycodes
(e.g. on Macs, with some X11 servers or with a VNC display). You
don't normally need to use it on PC/Linux or PC/Windows hosts.
The available layouts are:
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, tunable
parameters.
-soundhw card1[,card2,...] or -soundhw all
Enable audio and selected sound hardware. Use 'help' to print all
available 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 help
Note that Linux's i810_audio OSS kernel (for AC97) module might
require 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.
-device driver[,prop[=value][,...]]
Add device driver. prop=value sets driver properties. Valid
properties depend on the driver. To get help on possible drivers
and properties, use "-device help" and "-device driver,help".
-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.
Block device options:
-fda file
-fdb file
Use file as floppy disk 0/1 image. You can use the host floppy by
using /dev/fd0 as filename.
-hda file
-hdb file
-hdc file
-hdd file
Use file as hard disk 0, 1, 2 or 3 image.
-cdrom file
Use file as CD-ROM image (you cannot use -hdc and -cdrom at the
same time). You can use the host CD-ROM by using /dev/cdrom as
filename.
-drive option[,option[,option[,...]]]
Define a new drive. Valid options are:
file=file
This option defines which disk image to use with this drive. If
the filename contains comma, you must double it (for instance,
"file=my,,file" to use file "my,file").
Special files such as iSCSI devices can be specified using
protocol specific URLs. See the section for "Device URL Syntax"
for more information.
if=interface
This option defines on which type on interface the drive is
connected. Available types are: ide, scsi, sd, mtd, floppy,
pflash, virtio.
bus=bus,unit=unit
These options define where is connected the drive by defining
the bus number and the unit id.
index=index
This option defines where is connected the drive by using an
index in the list of available connectors of a given interface
type.
media=media
This option defines the type of the media: disk or cdrom.
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.
discard=discard
discard is one of "ignore" (or "off") or "unmap" (or "on") and
controls whether discard (also known as trim or unmap) requests
are ignored or passed to the filesystem. Some machine types
may not support discard requests.
format=format
Specify which disk format will be used rather than detecting
the format. Can be used to specifiy format=raw to avoid
interpreting an 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 the host 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
backing file sectors into the image file.
By default, the cache=writeback mode is used. It will report data
writes as completed as soon as the data is present in the host page
cache. This is safe as long as your guest OS makes sure to
correctly flush disk caches where needed. If your guest OS does not
handle volatile disk write caches correctly and your host crashes
or loses power, then the guest may experience data corruption.
For such guests, you should consider using cache=writethrough. This
means that the host page cache will be used to read and write data,
but write notification will be sent to the guest only after QEMU
has made sure to flush each write to the disk. Be aware that this
has a major impact on performance.
The host page cache can be avoided entirely with cache=none. This
will attempt to do disk IO directly to the guest's memory. QEMU
may still perform an internal copy of the data. Note that this is
considered a writeback mode and the guest OS must handle the disk
write cache correctly in order to avoid data corruption on host
crashes.
The host page cache can be avoided while only sending write
notifications to the guest when the data has been flushed to the
disk using cache=directsync.
In case you don't care about data integrity over host failures, use
cache=unsafe. This option tells QEMU that it never needs to write
any data to the disk but can instead keep things in cache. If
anything goes wrong, like your host losing power, the disk storage
getting disconnected accidentally, etc. your image will most
probably be rendered unusable. When using the -snapshot option,
unsafe caching is always used.
Copy-on-read avoids accessing the same backing file sectors
repeatedly and is useful when the backing file is over a slow
network. By default copy-on-read is off.
Instead of -cdrom you can use:
qemu-system-i386 -drive file=file,index=2,media=cdrom
Instead of -hda, -hdb, -hdc, -hdd, you can use:
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 open an image using pre-opened file descriptors from an fd
set:
qemu-system-i386
-add-fd fd=3,set=2,opaque="rdwr:/path/to/file"
-add-fd fd=4,set=2,opaque="rdonly:/path/to/file"
-drive file=/dev/fdset/2,index=0,media=disk
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 automatically
incremented:
qemu-system-i386 -drive file=a -drive file=b"
is interpreted like:
qemu-system-i386 -hda a -hdb b
-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.
-snapshot
Write to temporary files instead of disk image files. In this case,
the raw disk image you use is not written back. You can however
force the write back by pressing C-a s.
-hdachs c,h,s,[,t]
Force hard disk 0 physical geometry (1 <= c <= 16383, 1 <= h <= 16,
1 <= s <= 63) and optionally force the BIOS translation mode
(t=none, lba or auto). Usually QEMU can guess all those parameters.
This option is useful for old MS-DOS disk images.
-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
under this path will be available to the 9p client on the
guest.
security_model=security_model
Specifies the security model to be used for this export path.
Supported security models are "passthrough", "mapped-xattr",
"mapped-file" and "none". In "passthrough" security model,
files are stored using the same credentials as they are created
on the guest. This requires QEMU to run as root. In "mapped-
xattr" security model, some of the file attributes like uid,
gid, mode bits and link target are stored as file attributes.
For "mapped-file" these attributes are stored in the hidden
.virtfs_metadata directory. Directories exported by this
security model cannot interact with other unix tools. "none"
security model is same as passthrough except the sever won't
report failures if it fails to set file attributes like
ownership. Security model is mandatory only for local fsdriver.
Other fsdrivers (like handle, proxy) don't take security model
as a parameter.
writeout=writeout
This is an optional argument. The only supported value is
"immediate". This means that host page cache will be used to
read and write data but write notification will be sent to the
guest only when the data has been reported as written by the
storage subsystem.
readonly
Enables exporting 9p share as a readonly mount for guests. By
default read-write access is given.
socket=socket
Enables proxy filesystem driver to use passed socket file for
communicating with virtfs-proxy-helper
sock_fd=sock_fd
Enables proxy filesystem driver to use passed socket descriptor
for communicating with virtfs-proxy-helper. Usually a helper
like libvirt will create socketpair and pass one of the fds as
sock_fd
-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
-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
under this path will be available to the 9p client on the
guest.
security_model=security_model
Specifies the security model to be used for this export path.
Supported security models are "passthrough", "mapped-xattr",
"mapped-file" and "none". In "passthrough" security model,
files are stored using the same credentials as they are created
on the guest. This requires QEMU to run as root. In "mapped-
xattr" security model, some of the file attributes like uid,
gid, mode bits and link target are stored as file attributes.
For "mapped-file" these attributes are stored in the hidden
.virtfs_metadata directory. Directories exported by this
security model cannot interact with other unix tools. "none"
security model is same as passthrough except the sever won't
report failures if it fails to set file attributes like
ownership. Security model is mandatory only for local fsdriver.
Other fsdrivers (like handle, proxy) don't take security model
as a parameter.
writeout=writeout
This is an optional argument. The only supported value is
"immediate". This means that host page cache will be used to
read and write data but write notification will be sent to the
guest only when the data has been reported as written by the
storage subsystem.
readonly
Enables exporting 9p share as a readonly mount for guests. By
default read-write access is given.
socket=socket
Enables proxy filesystem driver to use passed socket file for
communicating with virtfs-proxy-helper. Usually a helper like
libvirt will create socketpair and pass one of the fds as
sock_fd
sock_fd
Enables proxy filesystem driver to use passed 'sock_fd' as the
socket descriptor for interfacing with virtfs-proxy-helper
-virtfs_synth
Create synthetic file system image
USB options:
-usb
Enable the USB driver (will be the default soon)
-usbdevice devname
Add the USB device devname.
mouse
Virtual Mouse. This will override the PS/2 mouse emulation when
activated.
tablet
Pointer device that uses absolute coordinates (like a
touchscreen). This means QEMU is able to report the mouse
position without having to grab the mouse. Also overrides the
PS/2 mouse emulation when activated.
disk:[format=format]:file
Mass storage device based on file. The optional format argument
will 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 the available devices.
braille
Braille device. This will use BrlAPI to display the braille
output on a real or fake device.
net:options
Network adapter that supports CDC ethernet and RNDIS protocols.
Display options:
-display type
Select type of display to use. This option is a replacement for the
old style -sdl/-curses/... options. Valid values for type are
sdl Display video output via SDL (usually in a separate graphics
window; see the SDL documentation for other possibilities).
curses
Display video output via curses. For graphics device models
which support a text mode, QEMU can display this output using a
curses/ncurses interface. Nothing is displayed when the
graphics device is in graphical mode or if the graphics device
does not support a text mode. Generally only the VGA device
models support text mode.
none
Do not display video output. The guest will still see an
emulated graphics card, but its output will not be displayed to
the QEMU user. This option differs from the -nographic option
in that it only affects what is done with video output;
-nographic also changes the destination of the serial and
parallel port data.
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
simple command line application. The emulated serial port is
redirected on the console. Therefore, you can still use QEMU to
debug a Linux kernel with a serial console.
-curses
Normally, QEMU uses SDL to display the VGA output. With this
option, QEMU can display the VGA output when in text mode using a
curses/ncurses interface. Nothing is displayed in graphical mode.
-no-frame
Do not use decorations for SDL windows and start them using the
whole available screen space. This makes the using QEMU in a
dedicated desktop workspace more convenient.
-alt-grab
Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
this also affects the special keys (for fullscreen, monitor-mode
switching, etc).
-ctrl-grab
Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
also affects the special keys (for fullscreen, monitor-mode
switching, etc).
-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 the system / user's SASL configuration file for
the 'qemu' service. This is typically found in
/etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
an environment variable SASL_CONF_PATH can be used to make it
search alternate locations for the service config. While some
SASL auth methods can also provide data encryption (eg GSSAPI),
it is recommended that SASL always be combined with the 'tls'
and 'x509' settings to enable use of SSL and server
certificates. This ensures a data encryption preventing
compromise of authentication credentials.
disable-ticketing
Allow client connects without authentication.
disable-copy-paste
Disable copy paste between the client and the guest.
tls-port=<nr>
Set the TCP port spice is listening on for encrypted channels.
x509-dir=<dir>
Set the x509 file directory. Expects same filenames as -vnc
$display,x509=$dir
x509-key-file=<file>
x509-key-password=<file>
x509-cert-file=<file>
x509-cacert-file=<file>
x509-dh-key-file=<file>
The x509 file names can also be configured individually.
tls-ciphers=<list>
Specify which ciphers to use.
tls-channel=[main|display|cursor|inputs|record|playback]
plaintext-channel=[main|display|cursor|inputs|record|playback]
Force specific channel to be used with or without TLS
encryption. The options can be specified multiple times to
configure multiple channels. The special name "default" can be
used to set the default mode. For channels which are not
explicitly forced into one mode the spice client is allowed to
pick tls/plaintext as he pleases.
image-compression=[auto_glz|auto_lz|quic|glz|lz|off]
Configure image compression (lossless). Default is auto_glz.
jpeg-wan-compression=[auto|never|always]
zlib-glz-wan-compression=[auto|never|always]
Configure wan image compression (lossy for slow links).
Default is auto.
streaming-video=[off|all|filter]
Configure video stream detection. Default is 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.
seamless-migration=[on|off]
Enable/disable spice seamless migration. Default is off.
-portrait
Rotate graphical output 90 deg left (only PXA LCD).
-rotate deg
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
from Windows 95 should recognize and use this graphic card. For
optimal performances, use 16 bit color depth in the guest and
the host OS. (This one is the default)
std Standard VGA card with Bochs VBE extensions. If your guest OS
supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
you want to use high resolution modes (>= 1280x1024x16) then
you should use this option.
vmware
VMWare SVGA-II compatible adapter. Use it if you have
sufficiently recent XFree86/XOrg server or Windows guest with a
driver for this card.
qxl QXL paravirtual graphic card. It is VGA compatible (including
VESA 2.0 VBE support). Works best with qxl guest drivers
installed though. Recommended choice when using the spice
protocol.
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 VGA display over the VNC session. It is very useful
to enable the usb tablet device when using this option (option
-usbdevice tablet). When using the VNC display, you must use the -k
parameter to set the keyboard layout if you are not using en-us.
Valid syntax for the display is
host:d
TCP connections will only be allowed from host on display d.
By convention the TCP port is 5900+d. Optionally, host can be
omitted in which case the server will accept connections from
any host.
unix:path
Connections will be allowed over UNIX domain sockets where path
is the location of a unix socket to listen for connections on.
none
VNC is initialized but not started. The monitor "change"
command can be used to later start the VNC server.
Following the display value there may be one or more option flags
separated by commas. Valid options are
reverse
Connect to a listening VNC client via a "reverse" connection.
The client is specified by the display. For reverse network
connections (host:d,"reverse"), the d argument is a TCP port
number, not a display number.
websocket
Opens an additional TCP listening port dedicated to VNC
Websocket connections. By definition the Websocket port is
5700+display. If host is specified connections will only be
allowed from this host. As an alternative the Websocket port
could be specified by using "websocket"=port. TLS encryption
for the Websocket connection is supported if the required
certificates are specified with the VNC option x509.
password
Require that password based authentication is used for client
connections.
The password must be set separately using the "set_password"
command in the pcsys_monitor. The syntax to change your
password is: "set_password <protocol> <password>" where
<protocol> could be either "vnc" or "spice".
If you would like to change <protocol> password expiration, you
should use "expire_password <protocol> <expiration-time>" where
expiration time could be one of the following options: now,
never, +seconds or UNIX time of expiration, e.g. +60 to make
password expire in 60 seconds, or 1335196800 to make password
expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for this
date and time).
You can also use keywords "now" or "never" for the expiration
time to allow <protocol> password to expire immediately or
never expire.
tls Require that client use TLS when communicating with the VNC
server. This uses anonymous TLS credentials so is susceptible
to a man-in-the-middle attack. It is recommended that this
option be combined with either the x509 or x509verify options.
x509=/path/to/certificate/dir
Valid if tls is specified. Require that x509 credentials are
used for negotiating the TLS session. The server will send its
x509 certificate to the client. It is recommended that a
password be set on the VNC server to provide authentication of
the client when this is used. The path following this option
specifies where the x509 certificates are to be loaded from.
See the vnc_security section for details on generating
certificates.
x509verify=/path/to/certificate/dir
Valid if tls is specified. Require that x509 credentials are
used for negotiating the TLS session. The server will send its
x509 certificate to the client, and request that the client
send its own x509 certificate. The server will validate the
client's certificate against the CA certificate, and reject
clients when validation fails. If the certificate authority is
trusted, this is a sufficient authentication mechanism. You may
still wish to set a password on the VNC server as a second
authentication layer. The path following this option specifies
where the x509 certificates are to be loaded from. See the
vnc_security section for details on generating certificates.
sasl
Require that the client use SASL to authenticate with the VNC
server. The exact choice of authentication method used is
controlled from the system / user's SASL configuration file for
the 'qemu' service. This is typically found in
/etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
an environment variable SASL_CONF_PATH can be used to make it
search alternate locations for the service config. While some
SASL auth methods can also provide data encryption (eg GSSAPI),
it is recommended that SASL always be combined with the 'tls'
and 'x509' settings to enable use of SSL and server
certificates. This ensures a data encryption preventing
compromise of authentication credentials. See the vnc_security
section for details on using SASL authentication.
acl Turn on access control lists for checking of the x509 client
certificate and SASL party. For x509 certs, the ACL check is
made against the certificate's distinguished name. This is
something that looks like "C=GB,O=ACME,L=Boston,CN=bob". For
SASL party, the ACL check is made against the username, which
depending on the SASL plugin, may include a realm component, eg
"bob" or "bob@EXAMPLE.COM". When the acl flag is set, the
initial access list will be empty, with a "deny" policy. Thus
no one will be allowed to use the VNC server until the ACLs
have been loaded. This can be achieved using the "acl" monitor
command.
lossy
Enable lossy compression methods (gradient, JPEG, ...). If this
option is set, VNC client may receive lossy framebuffer updates
depending on its encoding settings. Enabling this option can
save a lot of bandwidth at the expense of quality.
non-adaptive
Disable adaptive encodings. Adaptive encodings are enabled by
default. An adaptive encoding will try to detect frequently
updated screen regions, and send updates in these regions using
a lossy encoding (like JPEG). This can be really helpful to
save bandwidth when playing videos. Disabling adaptive
encodings allows to restore the original static behavior of
encodings like Tight.
share=[allow-exclusive|force-shared|ignore]
Set display sharing policy. 'allow-exclusive' allows clients
to ask for exclusive access. As suggested by the rfb spec this
is implemented by dropping other connections. Connecting
multiple clients in parallel requires all clients asking for a
shared session (vncviewer: -shared switch). This is the
default. 'force-shared' disables exclusive client access.
Useful for shared desktop sessions, where you don't want
someone forgetting specify -shared disconnect everybody else.
'ignore' completely ignores the shared flag and allows
everybody connect unconditionally. Doesn't conform to the rfb
spec but is traditional QEMU behavior.
i386 target only:
-win2k-hack
Use it when installing Windows 2000 to avoid a disk full bug. After
Windows 2000 is installed, you no longer need this option (this
option slows down the IDE transfers).
-no-fd-bootchk
Disable boot signature checking for floppy disks in Bochs BIOS. It
may be needed to boot from old floppy disks. TODO: check reference
to Bochs BIOS.
-no-acpi
Disable ACPI (Advanced Configuration and Power Interface) support.
Use it if your guest OS complains about ACPI problems (PC target
machine only).
-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 all ACPI headers (possible overridden by
other options). For data=, only data portion of the table is used,
all header information is specified in the command line.
-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 PC target.
Optionally, the MAC address can be changed to mac, the device
address set to addr (PCI cards only), and a name can be assigned
for use in monitor commands. Optionally, for PCI cards, you can
specify the number v of MSI-X vectors that the card should have;
this option currently only affects virtio cards; set v = 0 to
disable MSI-X. If no -net option is specified, a single NIC is
created. QEMU can emulate several different models of network
card. 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=help" for a list of available
devices for your target.
-netdev user,id=id[,option][,option][,...]
-net user[,option][,option][,...]
Use the user mode network stack which requires no administrator
privilege to run. Valid options are:
vlan=n
Connect user mode stack to VLAN n (n = 0 is the default).
id=id
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 is 10.0.2.0/24.
host=addr
Specify the guest-visible address of the host. Default is the
2nd IP in the guest network, i.e. x.x.x.2.
restrict=on|off
If this option is enabled, the guest will be isolated, i.e. it
will not be able to contact the host and no guest IP packets
will be routed over the host to the outside. This option does
not affect any explicitly set forwarding rules.
hostname=name
Specifies the client hostname reported by the built-in DHCP
server.
dhcpstart=addr
Specify the first of the 16 IPs the built-in DHCP server can
assign. Default is the 15th to 31st IP in the guest network,
i.e. x.x.x.15 to x.x.x.31.
dns=addr
Specify the guest-visible address of the virtual nameserver.
The address must be different from the host address. Default is
the 3rd IP in the guest network, i.e. x.x.x.3.
dnssearch=domain
Provides an entry for the domain-search list sent by the built-
in DHCP server. More than one domain suffix can be transmitted
by specifying this option multiple times. If supported, this
will cause the guest to automatically try to append the given
domain suffix(es) in case a domain name can not be resolved.
Example:
qemu-net user,dnssearch=mgmt.example.org,dnssearch=example.org [...]
tftp=dir
When using the user mode network stack, activate a built-in
TFTP server. The files in dir will be exposed as the root of a
TFTP server. The TFTP client on the guest must be configured
in binary mode (use the command "bin" of the Unix TFTP client).
bootfile=file
When using the user mode network stack, broadcast file as the
BOOTP filename. In conjunction with tftp, this can be used to
network boot a guest from a local directory.
Example (using pxelinux):
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 SMB
server so that Windows OSes can access to the host files in dir
transparently. The IP address of the SMB server can be set to
addr. By default the 4th IP in the guest network is used, i.e.
x.x.x.4.
In the guest Windows OS, the line:
10.0.2.4 smbserver
must be added in the file C:\WINDOWS\LMHOSTS (for windows
9x/Me) or C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS (Windows
NT/2000).
Then dir can be accessed in \smbserver\qemu.
Note that a SAMBA server must be installed on the host OS.
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 to the guest IP address guestaddr on guest port
guestport. If guestaddr is not specified, its value is x.x.x.15
(default first address given by the built-in DHCP server). By
specifying hostaddr, the rule can be bound to a specific host
interface. If no connection type is set, TCP is used. This
option can be given multiple times.
For example, to redirect host X11 connection from screen 1 to
guest screen 0, use the following:
# on the host
qemu-system-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 on the 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", you
connect to the guest telnet server.
guestfwd=[tcp]:server:port-dev
guestfwd=[tcp]:server:port-cmd:command
Forward guest TCP connections to the IP address server on port
port to the character device dev or to a program executed by
cmd:command which gets spawned for each connection. This option
can be given multiple times.
You can either use a chardev directly and have that one used
throughout QEMU's lifetime, like in the following example:
# open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
# the guest accesses it
qemu-net user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 [...]
Or you can execute a command on every TCP connection
established by the guest, so that QEMU behaves similar to an
inetd process for that virtual server:
# call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
# and connect the TCP stream to its stdin/stdout
qemu-net 'user,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
Note: Legacy stand-alone options -tftp, -bootp, -smb and -redir are
still processed and applied to -net user. Mixing them with the new
configuration syntax gives undefined results. Their use for new
applications is discouraged as they will be removed from future
versions.
-netdev
tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,helper=helper]
-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 script
dfile to deconfigure it. If name is not provided, the OS
automatically provides one. The default network configure script is
/etc/qemu-ifup and the default network deconfigure script is
/etc/qemu-ifdown. Use script=no or downscript=no to disable script
execution.
If running QEMU as an unprivileged user, use the network helper
helper to configure the TAP interface. The default network helper
executable is /usr/local/libexec/qemu-bridge-helper.
fd=h can be used to specify the handle of an already opened host
TAP interface.
Examples:
#launch a QEMU instance with the default network script
qemu-system-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"
-netdev bridge,id=id[,br=bridge][,helper=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 and
attach it to the bridge. The default network helper executable is
/usr/local/libexec/qemu-bridge-helper and the default bridge device
is br0.
Examples:
#launch a QEMU instance with the default network helper to
#connect a TAP device to bridge br0
qemu-system-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
-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]
-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 virtual machine
using a TCP socket connection. If listen is specified, QEMU waits
for incoming connections on port (host is optional). connect is
used to connect to another QEMU instance using the listen option.
fd=h specifies an already opened TCP socket.
Example:
# launch a first QEMU instance
qemu-system-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
-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]
-net
socket[,vlan=n][,name=name][,fd=h][,mcast=maddr:port[,localaddr=addr]]
Create a VLAN n shared with another QEMU virtual machines using a
UDP multicast socket, effectively making a bus for every QEMU with
same multicast address maddr and port. NOTES:
1. Several QEMU can be running on different hosts and share same
bus (assuming correct multicast setup for these hosts).
2. mcast support is compatible with User Mode Linux (argument
ethN=mcast), see <http://user-mode-linux.sf.net>.
3. Use fd=h to specify an already opened UDP multicast socket.
Example:
# launch one QEMU instance
qemu-system-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
-netdev
vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]
-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 and
listening for incoming connections on socketpath. Use GROUP
groupname and MODE octalmode to change default ownership and
permissions for communication port. This option is only available
if QEMU has been compiled with vde support enabled.
Example:
# launch vde switch
vde_switch -F -sock /tmp/myswitch
# launch QEMU instance
qemu-system-i386 linux.img -net nic -net vde,sock=/tmp/myswitch
-netdev hubport,id=id,hubid=hubid
Create a hub port on QEMU "vlan" hubid.
The hubport netdev lets you connect a NIC to a QEMU "vlan" instead
of a single netdev. "-net" and "-device" with parameter vlan
create the required hub automatically.
-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 is libpcap, 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
to override the default configuration (-net nic -net user) which is
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, ringbuf, file,
pipe, console, serial, pty, stdio, braille, tty, parallel, parport,
spicevmc. spiceport. The specific backend will determine the
applicable options.
All devices must have an id, which can be any string up to 127
characters long. It is used to uniquely identify this device in
other command line directives.
A character device may be used in multiplexing mode by multiple
front-ends. The key sequence of Control-a and c will rotate the
input focus between 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 it receives. 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. A unix socket will be created if path is specified.
Behaviour is undefined if TCP options are specified for a unix
socket.
server specifies that the socket shall be a listening socket.
nowait specifies that QEMU should not block waiting for a client to
connect to a listening socket.
telnet specifies that traffic on the socket should interpret telnet
escape sequences.
TCP and unix socket options are given below:
TCP options: port=port [,host=host] [,to=to] [,ipv4] [,ipv6]
[,nodelay]
host for a listening socket specifies the local address to be
bound. For a connecting socket species the remote host to
connect to. host is optional for listening sockets. If not
specified it defaults to 0.0.0.0.
port for a listening socket specifies the local port to be
bound. For a connecting socket specifies the port on the remote
host to connect to. port can be given as either a port number
or a service name. port is required.
to is only relevant to listening sockets. If it is specified,
and port cannot be bound, QEMU will attempt to bind to
subsequent ports up to and including to until it succeeds. to
must be specified as a port number.
ipv4 and ipv6 specify that either IPv4 or IPv6 must be used.
If neither is specified the socket may use either protocol.
nodelay disables the Nagle algorithm.
unix options: path=path
path specifies the local path of the unix socket. path is
required.
-chardev udp ,id=id [,host=host] ,port=port [,localaddr=localaddr]
[,localport=localport] [,ipv4] [,ipv6]
Sends all traffic from the guest to a remote host over UDP.
host specifies the remote host to connect to. If not specified it
defaults to "localhost".
port specifies the port on the remote host to connect to. port is
required.
localaddr specifies the local address to bind to. If not specified
it defaults to 0.0.0.0.
localport specifies the local port to bind to. If not specified any
available local port will be used.
ipv4 and ipv6 specify that either IPv4 or IPv6 must be used. If
neither is specified the device may use either protocol.
-chardev msmouse ,id=id
Forward QEMU's emulated msmouse events to the guest. msmouse does
not take any options.
-chardev vc ,id=id [[,width=width] [,height=height]] [[,cols=cols]
[,rows=rows]]
Connect to a QEMU text console. vc may optionally be given a
specific size.
width and height specify the width and height respectively of the
console, in pixels.
cols and rows specify that the console be sized to fit a text
console with the given dimensions.
-chardev ringbuf ,id=id [,size=size]
Create a ring buffer with fixed size size. size must be a power of
two, and defaults to "64K").
-chardev file ,id=id ,path=path
Log all traffic received from the guest to a file.
path specifies the path of the file to be opened. This file will be
created if it does not already exist, and overwritten if it does.
path is required.
-chardev pipe ,id=id ,path=path
Create a two-way connection to the guest. The behaviour differs
slightly between Windows hosts and other hosts:
On Windows, a single duplex pipe will be created at \.pipe\path.
On other hosts, 2 pipes will be created called path.in and
path.out. Data written to path.in will be received by the guest.
Data written by the guest can be read from path.out. QEMU will not
create these fifos, and requires them to be present.
path forms part of the pipe path as described above. path is
required.
-chardev console ,id=id
Send traffic from the guest to QEMU's standard output. console does
not take any options.
console is only available on Windows hosts.
-chardev serial ,id=id ,path=path
Send traffic from the guest to a serial device on the host.
On Unix hosts serial will actually accept any tty device, not only
serial lines.
path specifies the name of the serial device to open.
-chardev pty ,id=id
Create a new pseudo-terminal on the host and connect to it. pty
does not take any options.
pty is not available on Windows hosts.
-chardev stdio ,id=id [,signal=on|off]
Connect to standard input and standard output of the QEMU process.
signal controls if signals are enabled on the terminal, that
includes exiting QEMU with the key sequence Control-c. This option
is enabled by default, use signal=off to disable it.
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
tty is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD and
DragonFlyBSD hosts. It is an alias for serial.
path specifies the path to the tty. path is required.
-chardev parallel ,id=id ,path=path
-chardev parport ,id=id ,path=path
parallel is only available on Linux, FreeBSD and DragonFlyBSD
hosts.
Connect to a local parallel port.
path specifies the path to the parallel port device. path is
required.
-chardev spicevmc ,id=id ,debug=debug, name=name
spicevmc is only available when spice support is built in.
debug debug level for spicevmc
name name of spice channel to connect to
Connect to a spice virtual machine channel, such as vdiport.
-chardev spiceport ,id=id ,debug=debug, name=name
spiceport is only available when spice support is built in.
debug debug level for spicevmc
name name of spice port to connect to
Connect to a spice port, allowing a Spice client to handle the
traffic identified by a name (preferably a fqdn).
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 are specified using a special URL syntax.
iSCSI
iSCSI support allows QEMU to access iSCSI resources directly and
use as images for the guest storage. Both disk and cdrom images are
supported.
Syntax for specifying iSCSI LUNs is
"iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>"
By default qemu will use the iSCSI initiator-name
'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from
the command line or a configuration file.
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
when compiled and linked against libiscsi.
iSCSI parameters such as username and password can also be
specified via a configuration file. See qemu-doc for more
information and examples.
NBD QEMU supports NBD (Network Block Devices) both using TCP protocol
as well as Unix Domain Sockets.
Syntax for specifying a NBD device using TCP
"nbd:<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
SSH QEMU supports SSH (Secure Shell) access to remote disks.
Examples:
qemu-system-i386 -drive file=ssh://user@host/path/to/disk.img
qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
Currently authentication must be done using ssh-agent. Other
authentication methods may be supported in future.
Sheepdog
Sheepdog is a distributed storage system for QEMU. QEMU supports
using either local sheepdog devices or remote networked devices.
Syntax for specifying a sheepdog device
sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]
Example
qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
See also <http://http://www.osrg.net/sheepdog/>.
GlusterFS
GlusterFS is an user space distributed file system. QEMU supports
the use of GlusterFS volumes for hosting VM disk images using TCP,
Unix Domain Sockets and RDMA transport protocols.
Syntax for specifying a VM disk image on GlusterFS volume is
gluster[+transport]://[server[:port]]/volname/image[?socket=...]
Example
qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img
See also <http://www.gluster.org>.
Bluetooth(R) options:
-bt hci[...]
Defines the function of the corresponding Bluetooth HCI. -bt
options are matched with the HCIs present in the chosen machine
type. For example when emulating a machine with only one HCI built
into it, only the first "-bt hci[...]" option is valid and defines
the HCI's logic. The Transport Layer is decided by the machine
type. Currently the machines "n800" and "n810" have one HCI and
all other machines have none.
The following three types are recognized:
-bt hci,null
(default) The corresponding Bluetooth HCI assumes no internal
logic and will not respond to any HCI commands or emit events.
-bt hci,host[:id]
("bluez" only) The corresponding HCI passes commands / events
to / from the physical HCI identified by the name id (default:
"hci0") on the computer running QEMU. Only available on
"bluez" capable systems like Linux.
-bt hci[,vlan=n]
Add a virtual, standard HCI that will participate in the
Bluetooth scatternet n (default 0). Similarly to -net VLANs,
devices inside a bluetooth network n can only communicate with
other devices in the same network (scatternet).
-bt vhci[,vlan=n]
(Linux-host only) Create a HCI in scatternet n (default 0) attached
to the host bluetooth stack instead of to the emulated target.
This allows the host and target machines to participate in a common
scatternet and communicate. Requires the Linux "vhci" driver
installed. Can be 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 devices currently:
keyboard
Virtual wireless keyboard implementing the HIDP bluetooth
profile.
TPM device options:
The general form of a TPM device option is:
-tpmdev backend ,id=id [,options]
Backend type must be: passthrough.
The specific backend type will determine the applicable options.
The "-tpmdev" option creates the TPM backend and requires a
"-device" option that specifies the TPM frontend interface model.
Options to each backend are described below.
Use 'help' to print all available TPM backend types.
qemu-tpmdev help
-tpmdev passthrough, id=id, path=path, cancel-path=cancel-path
(Linux-host only) Enable access to the host's TPM using the
passthrough driver.
path specifies the path to the host's TPM device, i.e., on a Linux
host this would be "/dev/tpm0". path is optional and by default
"/dev/tpm0" is used.
cancel-path specifies the path to the host TPM device's sysfs entry
allowing for cancellation of an ongoing TPM command. cancel-path
is optional and by default QEMU will search for the sysfs entry to
use.
Some notes about using the host's TPM with the passthrough driver:
The TPM device accessed by the passthrough driver must not be used
by any other application on the host.
Since the host's firmware (BIOS/UEFI) has already initialized the
TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
the TPM again and may therefore not show a TPM-specific menu that
would otherwise allow the user to configure the TPM, e.g., allow
the user to enable/disable or activate/deactivate the TPM.
Further, if TPM ownership is released from within a VM then the
host's TPM will get disabled and deactivated. To enable and
activate the TPM again afterwards, the host has to be rebooted and
the user is required to enter the firmware's menu to enable and
activate the TPM. If the TPM is left disabled and/or deactivated
most TPM commands will fail.
To create a passthrough TPM use the following two options:
-tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
Note that the "-tpmdev" id is "tpm0" and is referenced by
"tpmdev=tpm0" in the device option.
Linux/Multiboot boot specific:
When using these options, you can use a given Linux or Multiboot kernel
without installing it in the disk image. It can be useful for easier
testing of various kernels.
-kernel bzImage
Use bzImage as kernel image. The kernel can be either a Linux
kernel or 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 the
first module.
-dtb file
Use file as a device tree binary (dtb) image and pass it to the
kernel on 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 serial
ports.
Use "-serial none" to disable all serial ports.
Available character devices are:
vc[:WxH]
Virtual console. Optionally, a width and height can be given in
pixel with
vc:800x600
It is also possible to specify width or height in characters:
vc:80Cx24C
pty [Linux only] Pseudo TTY (a new PTY is automatically allocated)
none
No device is allocated.
null
void device
/dev/XXX
[Linux only] Use host tty, e.g. /dev/ttyS0. The host serial
port parameters are set according to the emulated ones.
/dev/parportN
[Linux only, parallel port only] Use host parallel port N.
Currently SPP and EPP parallel port features can be used.
file:filename
Write output to filename. No character can be read.
stdio
[Unix only] standard input/output
pipe:filename
name pipe filename
COMn
[Windows only] Use host serial port n
udp:[remote_host]:remote_port[@[src_ip]:src_port]
This implements UDP Net Console. When remote_host or src_ip
are not specified they default to 0.0.0.0. When not using a
specified src_port a random port is automatically chosen.
If you just want a simple readonly console you can use "netcat"
or "nc", by starting QEMU with: "-serial udp::4555" and nc as:
"nc -u -l -p 4555". Any time QEMU writes something to that port
it will appear in the netconsole session.
If you plan to send characters back via netconsole or you want
to stop and start QEMU a lot of times, you should have QEMU use
the same source port each time by using something like "-serial
udp::4555@4556" to QEMU. Another approach is to use a patched
version of netcat which can listen to a TCP port and send and
receive characters via udp. If you have a patched version of
netcat which activates telnet remote echo and single char
transfer, then you can use the following options to step up a
netcat redirector to allow telnet on port 5555 to access the
QEMU port.
"QEMU Options:"
-serial udp::4555@4556
"netcat options:"
-u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
"telnet options:"
localhost 5555
tcp:[host]:port[,server][,nowait][,nodelay]
The TCP Net Console has two modes of operation. It can send
the serial I/O to a location or wait for a connection from a
location. By default the TCP Net Console is sent to host at
the port. If you use the server option QEMU will wait for a
client socket application to connect to the port before
continuing, unless the "nowait" option was specified. The
"nodelay" option disables the Nagle buffering algorithm. If
host is omitted, 0.0.0.0 is assumed. Only one TCP connection at
a time is accepted. You can use "telnet" to connect to the
corresponding character device.
"Example to send tcp console to 192.168.0.2 port 4444"
-serial tcp:192.168.0.2:4444
"Example to listen and wait on port 4444 for connection"
-serial tcp::4444,server
"Example to not wait and listen on ip 192.168.0.100 port 4444"
-serial tcp:192.168.0.100:4444,server,nowait
telnet:host:port[,server][,nowait][,nodelay]
The telnet protocol is used instead of raw tcp sockets. The
options work the same as if you had specified "-serial tcp".
The difference is that the port acts like a telnet server or
client using telnet option negotiation. This will also allow
you to send the MAGIC_SYSRQ sequence if you use a telnet that
supports sending the break sequence. Typically in unix telnet
you do it with Control-] and then type "send break" followed by
pressing the enter key.
unix:path[,server][,nowait]
A unix domain socket is used instead of a tcp socket. The
option works the same as if you had specified "-serial tcp"
except the unix domain socket path is used for connections.
mon:dev_string
This is a special option to allow the monitor to be multiplexed
onto another serial port. The monitor is accessed with key
sequence of Control-a and then pressing c. See monitor access
pcsys_keys in the -nographic section for more keys. dev_string
should be any one of the serial devices specified above. An
example to multiplex the monitor onto a telnet server listening
on port 4444 would be:
"-serial mon:telnet::4444,server,nowait"
braille
Braille device. This will use BrlAPI to display the braille
output on a real or fake device.
msmouse
Three button serial mouse. Configure the guest to use Microsoft
protocol.
-parallel dev
Redirect the virtual parallel port to host device dev (same devices
as the serial port). On Linux hosts, /dev/parportN can be used to
use hardware devices connected on the corresponding host parallel
port.
This option can be used several times to simulate up to 3 parallel
ports.
Use "-parallel none" to disable all parallel ports.
-monitor dev
Redirect the monitor to host device dev (same devices as the serial
port). The default device is "vc" in graphical mode and "stdio" in
non graphical mode.
-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 the
serial port). The debug console is an I/O port which is typically
port 0xe9; writing to that I/O port sends output to this device.
The default device is "vc" in graphical mode and "stdio" in non
graphical mode.
-pidfile file
Store the QEMU process PID in file. It is useful if you launch QEMU
from a script.
-singlestep
Run the emulation in single step mode.
-S Do not start CPU at startup (you must type 'c' in the monitor).
-realtime mlock=on|off
Run qemu with realtime features. mlocking qemu and guest memory
can be enabled via mlock=on (enabled by default).
-gdb dev
Wait for gdb connection on device dev. Typical connections will
likely be TCP-based, but also UDP, pseudo TTY, or even stdio are
reasonable use case. The latter is allowing to start QEMU from
within gdb and establish the connection via a pipe:
(gdb) target remote | exec qemu-system-i386 -gdb stdio ...
-s Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port
1234.
-d item1[,...]
Enable logging of specified items. Use '-d help' for a list of log
items.
-D logfile
Output log in logfile instead of to stderr
-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
available if 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 the disk image.
-loadvm file
Start right away with a saved state ("loadvm" in monitor)
-daemonize
Daemonize the QEMU process after initialization. QEMU will not
detach from standard IO until it is ready to receive connections on
any of its devices. This option is a useful way for external
programs to launch QEMU without having to cope with initialization
race conditions.
-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
timers are available use "-clock help".
-rtc [base=utc|localtime|date][,clock=host|vm][,driftfix=none|slew]
Specify base as "utc" or "localtime" to let the RTC start at the
current UTC or local time, respectively. "localtime" is required
for correct date in MS-DOS or Windows. To start at a specific point
in time, provide date in the format "2006-06-17T16:01:21" or
"2006-06-17". The default base is UTC.
By default the RTC is driven by the host system time. This allows
to use the RTC as accurate reference clock inside the guest,
specifically if the host time is smoothly following an accurate
external reference clock, e.g. via NTP. If you want to isolate the
guest time from the host, you can set clock to "rt" instead. 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 how many timer interrupts were not processed by the
Windows guest and will re-inject them.
-icount [N|auto]
Enable virtual instruction counter. The virtual cpu will execute
one instruction every 2^N ns of virtual time. If "auto" is
specified then the virtual cpu speed will be automatically adjusted
to keep virtual time within a few seconds of real time.
Note that while this option can give deterministic behavior, it
does not provide cycle accurate emulation. Modern CPUs contain
superscalar out of order cores with complex cache hierarchies. The
number of instructions executed often has little or no correlation
with actual performance.
-watchdog model
Create a virtual hardware watchdog device. Once enabled (by a
guest action), the watchdog must be periodically polled by an agent
inside the guest or else the guest will be restarted.
The model is the model of hardware watchdog to emulate. Choices
for model are: "ib700" (iBASE 700) which is a very simple ISA
watchdog with a single timer, or "i6300esb" (Intel 6300ESB I/O
controller hub) which is a much more featureful PCI-based dual-
timer watchdog. Choose a model for which your guest has drivers.
Use "-watchdog help" to list available hardware models. Only one
watchdog can be enabled for a guest.
-watchdog-action action
The action controls what QEMU will do when the watchdog timer
expires. The default is "reset" (forcefully reset the guest).
Other possible actions are: "shutdown" (attempt to gracefully
shutdown the guest), "poweroff" (forcefully poweroff the guest),
"pause" (pause the guest), "debug" (print a debug message and
continue), or "none" (do nothing).
Note that the "shutdown" action requires that the guest responds to
ACPI signals, which it may not be able to do in the sort of
situations where the watchdog would have expired, and thus
"-watchdog-action shutdown" is not recommended for production use.
Examples:
"-watchdog i6300esb -watchdog-action pause"
"-watchdog ib700"
-echr numeric_ascii_value
Change the escape character used for switching to the monitor when
using monitor and serial sharing. The default is 0x01 when using
the "-nographic" option. 0x01 is equal to pressing "Control-a".
You can select a different character from the ascii control keys
where 1 through 26 map to Control-a through Control-z. For
instance you could use the either of the following to change the
escape character to Control-t.
"-echr 0x14"
"-echr 20"
-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. Normally, QEMU sets the default
devices like serial port, parallel port, virtual console, monitor
device, VGA adapter, floppy and CD-ROM drive and others. The
"-nodefaults" option will disable all those default devices.
-chroot dir
Immediately before starting guest execution, chroot to the
specified directory. Especially useful in combination with -runas.
-runas user
Immediately before starting guest execution, drop root privileges,
switching to 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).
-sandbox arg
Enable Seccomp mode 2 system call filter. 'on' will enable syscall
filtering and 'off' will disable it. The default is 'off'.
-readconfig file
Read device configuration from file. This approach is useful when
you want to spawn QEMU process with many command line options but
you don't want to exceed the command line character limit.
-writeconfig file
Write device configuration to file. The file can be either filename
to save command line and device configuration into file or dash
"-") character to print the output to stdout. This can be later
used as input file for "-readconfig" option.
-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-
provided config files on sysconfdir, but won't make it skip the
QEMU-provided config files 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
with either simple or stderr tracing backend.
file=file
Log output traces to file.
This option is only available if QEMU has been compiled with
the simple tracing backend.
-enable-fips
Enable FIPS 140-2 compliance mode.
-object typename[,prop1=value1,...]
Create an new object of type typename setting properties in the
order they are specified. Note that the 'id' property must be set.
These objects are placed in the '/objects' path.
During the graphical emulation, you can use special key combinations to
change modes. The default key mappings are shown below, but if you use
"-alt-grab" then 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
Ctrl-Alt--
Shrink the screen
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
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.
The following options are specific to the Sparc32 emulation:
-g WxHx[xDEPTH]
Set the initial TCX graphic mode. The default is 1024x768x8,
currently the 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.
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.
SEE ALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
AUTHOR
Fabrice Bellard
2013-06-05 QEMU(1)
