man qemu (Commandes) - QEMU System Emulator


qemu - QEMU System Emulator


usage: qemu [options] [disk_image]


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
NE2000 PCI network adapters
Serial ports
Creative SoundBlaster 16 sound card
ENSONIQ AudioPCI ES1370 sound card
Adlib(OPL2) - Yamaha YM3812 compatible chip
PCI UHCI USB controller and a virtual USB hub.

SMP is supported with up to 255 CPUs.

Note that adlib is only available when QEMU was configured with -enable-adlib

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

QEMU uses YM3812 emulation by Tatsuyuki Satoh.


disk_image is a raw hard disk image for IDE hard disk 0.

General options:

-M machine
Select the emulated machine (CW-M ? for list)
-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 and -cdrom at the same time). You can use the host CD-ROM by using /dev/cdrom as filename.
-boot [a|c|d]
Boot on floppy (a), hard disk (c) or CD-ROM (d). Hard disk boot is the default.
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 MB.
-smp n
Simulate an SMP system with n CPUs. On the PC target, up to 255 CPUs are supported.
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.
-k language
Use keyboard layout language (for example CWfr for French). This option is only needed where it is not easy to get raw PC keycodes (e.g. on Macs or with some X11 servers). You don't 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 CWen-us.
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 hda
        qemu -soundhw es1370 hda
        qemu -soundhw all hda
        qemu -soundhw ?
Set the real time clock to local time (the default is to UTC time). This option is needed to have correct date in MS-DOS or Windows.
Start in full screen.
-pidfile file
Store the QEMU process PID in file. It is useful if you launch QEMU from a script.
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).

USB options:

Enable the USB driver (will be the default soon)
-usbdevice devname
Add the USB device devname. See the monitor command CWusb_add to have more information.

Network options:

-net nic[,vlan=n][,macaddr=addr]
Create a new Network Interface Card and connect it to VLAN n (n = 0 is the default). The NIC is currently an NE2000 on the PC target. Optionally, the MAC address can be changed. If no -net option is specified, a single NIC is created.
-net user[,vlan=n]
Use the user mode network stack which requires no administrator priviledge to run. This is the default if no -net option is specified.
-net tap[,vlan=n][,fd=h][,ifname=name][,script=file]
Connect the host TAP network interface name to VLAN n and use the network script file to configure it. The default network script is /etc/qemu-ifup. 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. 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][,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=
-net socket[,vlan=n][,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:
Several QEMU can be running on different hosts and share same bus (assuming correct multicast setup for these hosts).
mcast support is compatible with User Mode Linux (argument ethN=mcast), see <>.
3.<Use fd=h to specify an already opened UDP multicast socket.>
        # launch one QEMU instance
        qemu linux.img -net nic,macaddr=52:54:00:12:34:56 -net socket,mcast=
        # launch another QEMU instance on same "bus"
        qemu linux.img -net nic,macaddr=52:54:00:12:34:57 -net socket,mcast=
        # launch yet another QEMU instance on same "bus"
        qemu linux.img -net nic,macaddr=52:54:00:12:34:58 -net socket,mcast=
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=
        # launch UML
        /path/to/linux ubd0=/path/to/root_fs eth0=mcast
-net none
Indicate that no network devices should be configured. It is used to override the default configuration which is activated if no -net options are provided.
-tftp prefix
When using the user mode network stack, activate a built-in TFTP server. All filenames beginning with prefix can be downloaded from the host to the guest using a TFTP client. The TFTP client on the guest must be configured in binary mode (use the command CWbin of the Unix TFTP client). The host IP address on the guest is as usual
-smb dir
When using the user mode network stack, activate a built-in SMB server so that Windows OSes can access to the host files in dir transparently. In the guest Windows OS, the line: 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 version 2.2.7a from the Red Hat 9 and version 3.0.10-1.fc3 from Fedora Core 3.
-redir [tcp|udp]:host-port:[guest-host]:guest-port
When using the user mode network stack, redirect incoming TCP or UDP connections to the host port host-port to the guest guest-host on guest port guest-port. If guest-host is not specified, its value is (default address given by the built-in DHCP server). For example, to redirect host X11 connection from screen 1 to guest screen 0, use the following:
        # on the host
        qemu -redir tcp: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 -redir tcp:5555::23 [...]
        telnet localhost 5555
Then when you use on the host CWtelnet localhost 5555, you connect to the guest telnet server.

Linux boot specific: When using these options, you can use a given Linux kernel without installing it in the disk image. It can be useful for easier testing of various kernels.

-kernel bzImage
Use bzImage as kernel image.
-append cmdline
Use cmdline as kernel command line
-initrd file
Use file as initial ram disk.

Debug/Expert options:

-serial dev
Redirect the virtual serial port to host device dev. Available devices are: Virtual console [Linux only] Pseudo TTY (a new PTY is automatically allocated) void device [Linux only] Use host tty, e.g. /dev/ttyS0. The host serial port parameters are set according to the emulated ones. [Linux only, parallel port only] Use host parallel port N. Currently only SPP parallel port features can be used. Write output to filename. No character can be read. [Unix only] standard input/output [Unix only] name pipe filename The default device is CWvc in graphical mode and CWstdio in non graphical mode. This option can be used several times to simulate up to 4 serials ports.
-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.
-monitor dev
Redirect the monitor to host device dev (same devices as the serial port). The default device is CWvc in graphical mode and CWstdio in non graphical mode.
Wait gdb connection to port 1234
-p port
Change gdb connection port.
Do not start CPU at startup (you must type 'c' in the monitor).
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 thoses parameters. This option is useful for old MS-DOS disk images.
Simulate a standard VGA card with Bochs VBE extensions (default is Cirrus Logic GD5446 PCI VGA)
-loadvm file
Start right away with a saved state (CWloadvm in monitor)

During the graphical emulation, you can use the following keys:

Toggle full screen
Switch to virtual console 'n'. Standard console mappings are:
Target system display
Serial port
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
Print this help
Ctrl-a x
Exit emulator
Ctrl-a s
Save disk data back to file (if -snapshot)
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.

The following options are specific to the Sparc emulation:

-g WxH
Set the initial TCX graphic mode. The default is 1024x768.


The HTML documentation of QEMU for more precise information and Linux user mode emulator invocation.


Fabrice Bellard