NAME
qemu-doc - QEMU Emulator User Documentation
SYNOPSIS
usage: qemu [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
- 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 was
configured with --audio-card-list option containing the name(s) of
required card(s).
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" SchA~Xtz.
Not 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 dos.img -soundhw gus -parallel none
Alternatively:
qemu 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
-M machine
Select the emulated machine ("-M ?" for list)
-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 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.
-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").
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", 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 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).
By default, writethrough caching is used for all block device.
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 when the
data has been reported as written by the storage subsystem.
Writeback caching will report data writes as completed as soon as
the data is present 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 data corruption. When using the -snapshot
option, writeback caching is used by default.
The host page cache can be avoided entirely with cache=none. This
will attempt to do disk IO directly to the guests memory. QEMU may
still perform an internal copy of the data.
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.
Instead of -cdrom you can use:
qemu -drive file=file,index=2,media=cdrom
Instead of -hda, -hdb, -hdc, -hdd, you can use:
qemu -drive file=file,index=0,media=disk
qemu -drive file=file,index=1,media=disk
qemu -drive file=file,index=2,media=disk
qemu -drive file=file,index=3,media=disk
You can connect a CDROM to the slave of ide0:
qemu -drive file=file,if=ide,index=1,media=cdrom
If you don't specify the "file=" argument, you define an empty
drive:
qemu -drive if=ide,index=1,media=cdrom
You can connect a SCSI disk with unit ID 6 on the bus #0:
qemu -drive file=file,if=scsi,bus=0,unit=6
Instead of -fda, -fdb, you can use:
qemu -drive file=file,index=0,if=floppy
qemu -drive file=file,index=1,if=floppy
By default, interface is "ide" and index is automatically
incremented:
qemu -drive file=a -drive file=b"
is interpreted like:
qemu -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.
-boot [order=drives][,once=drives][,menu=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.
# try to boot from network first, then from hard disk
qemu -boot order=nc
# boot from CD-ROM first, switch back to default order after reboot
qemu -boot once=d
Note: The legacy format '-boot drives' is still supported but its
use 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
force the write back by pressing C-a s.
-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.
-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 ? to print all
available sound hardware.
qemu -soundhw sb16,adlib disk.img
qemu -soundhw es1370 disk.img
qemu -soundhw ac97 disk.img
qemu -soundhw all disk.img
qemu -soundhw ?
Note that Linux's i810_audio OSS kernel (for AC97) module might
require manually specifying clocking.
modprobe i810_audio clocking=48000
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.
-device driver[,option[,...]]
Add device driver. Depending on the device type, option (typically
key=value) may be useful.
-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:
-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).
-ctrl-grab
Use Right-Ctrl to grab mouse (instead of Ctrl-Alt).
-no-quit
Disable SDL window close capability.
-sdl
Enable SDL.
-portrait
Rotate graphical output 90 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.
none
Disable VGA card.
-full-screen
Start in full screen.
-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.
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. 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.
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.
-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.
-balloon none
Disable balloon device.
-balloon virtio[,addr=addr]
Enable virtio balloon device (default), optionally with PCI address
addr.
-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.
-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=? for a list of available
devices for your target.
-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).
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 10.0.2.0/8.
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=y|yes|n|no
If this options 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 explicitly set forwarding rule.
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. Default is the 16th to 31st IP in the guest network,
i.e. x.x.x.16 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.
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 -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 in
/usr/sbin/smbd. 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 -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 -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
Forward guest TCP connections to the IP address server on port
port to the character device dev. This option can be given
multiple times.
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.
-net
tap[,vlan=n][,name=name][,fd=h][,ifname=name][,script=file][,downscript=dfile]
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. fd=h can be used to specify the handle of an already
opened host TAP interface. 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. Example:
qemu linux.img -net nic -net tap
More complicated example (two NICs, each one connected to a TAP
device)
qemu linux.img -net nic,vlan=0 -net tap,vlan=0,ifname=tap0 \
-net nic,vlan=1 -net tap,vlan=1,ifname=tap1
-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 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 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]
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 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 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 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 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
-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 available only
if QEMU has been compiled with vde support enabled.
Example:
# launch vde switch
vde_switch -F -sock /tmp/myswitch
# launch QEMU instance
qemu 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 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 [,options]
Backend is one of: null, socket, udp, msmouse, vc, file, pipe,
console, serial, pty, stdio, braille, tty, parport. 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.
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=host [,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 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.
serial is only 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
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
Connect to a local tty device.
tty is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD and
DragonFlyBSD 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 is
required.
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 [...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.
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.
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.
-mon chardev=[name][,mode=readline|control][,default]
Setup monitor on chardev name.
-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).
-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 -gdb stdio ...
-s Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port
1234.
-d Output log in /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 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.
-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.
-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 ?.
-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, even prevent it from progressing during
suspension, you can set clock to "vm" instead.
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 ?" 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.
-nodefaults
Don't create 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.
-readconfig file
Read device configuration from file.
-writeconfig file
Write device configuration to file.
During the graphical emulation, you can use the following keys:
Ctrl-Alt-f
Toggle full 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
2010-09-06