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Qemu is a machine emulator & system virtualizer.

Windows NT 4.0 MIPS under Qemu

Qemu can emulate numerious CPUs and machine types. Most are geared towards running Linux, the x86/x64 emulators are the most flexible, and most well used. The current version is 2.3.0.

As of 0.15.0 the following machine emulators are available:

While not active, there is also the following in the tree:

  • Dec Alpha (really incomplete)

Running Qemu

Qemu is driven by command line arguments... The first thing that you typically do is setup a virtual hard disk with qemu-img. Once your disk is ready then you can configure each system emulator with various flags.


qemu-img version 0.14.92, Copyright (c) 2004-2008 Fabrice Bellard
usage: qemu-img command [command options]
QEMU disk image utility

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

Command parameters:
  'filename' is a disk image filename
  'fmt' is the disk image format. It is guessed automatically in most cases
  'cache' is the cache mode used to write the output disk image, the valid
    options are: 'none', 'writeback' (default), 'writethrough' and 'unsafe'
  'size' is the disk image size in bytes. Optional suffixes
    'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M)
    and T (terabyte, 1024G) are supported. 'b' is ignored.
  'output_filename' is the destination disk image filename
  'output_fmt' is the destination format
  'options' is a comma separated list of format specific options in a
    name=value format. Use -o ? for an overview of the options supported by the
    used format
  '-c' indicates that target image must be compressed (qcow format only)
  '-u' enables unsafe rebasing. It is assumed that old and new backing file
       match exactly. The image doesn't need a working backing file before
       rebasing in this case (useful for renaming the backing file)
  '-h' with or without a command shows this help and lists the supported formats
  '-p' show progress of command (only certain commands)

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

Supported formats: raw cow qcow vdi vmdk cloop dmg bochs vpc vvfat qcow2 qed parallels nbd blkdebug sheepdog blkverify host_device file


Please note that some of these flags change between versions

Qemu 0.15.0 rc2

QEMU emulator version 0.14.92, Copyright (c) 2003-2008 Fabrice Bellard
usage: qemu [options] [disk_image]

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

Standard options:
-h or -help     display this help and exit
-version        display version information and exit
-machine [type=]name[,prop[=value][,...]]
                selects emulated machine (-machine ? for list)
                property accel=accel1[:accel2[:...]] selects accelerator
                supported accelerators are kvm, xen, tcg (default: tcg)
-cpu cpu        select CPU (-cpu ? for list)
-smp n[,maxcpus=cpus][,cores=cores][,threads=threads][,sockets=sockets]
                set the number of CPUs to 'n' [default=1]
                maxcpus= maximum number of total cpus, including
                offline CPUs for hotplug, etc
                cores= number of CPU cores on one socket
                threads= number of threads on one CPU core
                sockets= number of discrete sockets in the system
-numa node[,mem=size][,cpus=cpu[-cpu]][,nodeid=node]
-fda/-fdb file  use 'file' as floppy disk 0/1 image
-hda/-hdb file  use 'file' as IDE hard disk 0/1 image
-hdc/-hdd file  use 'file' as IDE hard disk 2/3 image
-cdrom file     use 'file' as IDE cdrom image (cdrom is ide1 master)
-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]
                use 'file' as a drive image
-set group.id.arg=value
                set <arg> parameter for item <id> of type <group>
                i.e. -set drive.$id.file=/path/to/image
-global driver.property=value
                set a global default for a driver property
-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]
                'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)
-snapshot       write to temporary files instead of disk image files
-m megs         set virtual RAM size to megs MB [default=128]
-mem-path FILE  provide backing storage for guest RAM
-k language     use keyboard layout (for example 'fr' for French)
-audio-help     print list of audio drivers and their options
-soundhw c1,... enable audio support
                and only specified sound cards (comma separated list)
                use -soundhw ? to get the list of supported cards
                use -soundhw all to enable all of them
-usb            enable the USB driver (will be the default soon)
-usbdevice name add the host or guest USB device 'name'
-device driver[,prop[=value][,...]]
                add device (based on driver)
                prop=value,... sets driver properties
                use -device ? to print all possible drivers
                use -device driver,? to print all possible properties
File system options:
-fsdev local,id=id,path=path,security_model=[mapped|passthrough|none]
Virtual File system pass-through options:
-virtfs local,path=path,mount_tag=tag,security_model=[mapped|passthrough|none]

-name string1[,process=string2]
                set the name of the guest
                string1 sets the window title and string2 the process name (on Linux)
-uuid %08x-%04x-%04x-%04x-%012x
                specify machine UUID

Display options:
-display sdl[,frame=on|off][,alt_grab=on|off][,ctrl_grab=on|off]
                select display type
-nographic      disable graphical output and redirect serial I/Os to console
-curses         use a curses/ncurses interface instead of SDL
-no-frame       open SDL window without a frame and window decorations
-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
-spice <args>   enable spice
-portrait       rotate graphical output 90 deg left (only PXA LCD)
-rotate <deg>   rotate graphical output some deg left (only PXA LCD)
-vga [std|cirrus|vmware|qxl|xenfb|none]
                select video card type
-full-screen    start in full screen
-g WxH[xDEPTH]  Set the initial graphical resolution and depth
-vnc display    start a VNC server on display

1 target only:
-win2k-hack     use it when installing Windows 2000 to avoid a disk full bug
-no-fd-bootchk  disable boot signature checking for floppy disks
-no-acpi        disable ACPI
-no-hpet        disable HPET
-balloon none   disable balloon device
-balloon virtio[,addr=str]
                enable virtio balloon device (default)
-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]...]
                ACPI table description
-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]
                specify SMBIOS type 1 fields

Network options:
-net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]
                create a new Network Interface Card and connect it to VLAN 'n'
-net user[,vlan=n][,name=str][,net=addr[/mask]][,host=addr][,restrict=on|off]
         [,hostfwd=rule][,guestfwd=rule]                connect the user mode network stack to VLAN 'n', configure its
                DHCP server and enabled optional services
-net tap[,vlan=n][,name=str],ifname=name
                connect the host TAP network interface to VLAN 'n'
-net socket[,vlan=n][,name=str][,fd=h][,listen=[host]:port][,connect=host:port]
                connect the vlan 'n' to another VLAN using a socket connection
-net socket[,vlan=n][,name=str][,fd=h][,mcast=maddr:port[,localaddr=addr]]
                connect the vlan 'n' to multicast maddr and port
                use 'localaddr=addr' to specify the host address to send packets from
-net dump[,vlan=n][,file=f][,len=n]
                dump traffic on vlan 'n' to file 'f' (max n bytes per packet)
-net none       use it alone to have zero network devices. If no -net option
                is provided, the default is '-net nic -net user'
-netdev [user|tap|socket],id=str[,option][,option][,...]

Character device options:
-chardev null,id=id[,mux=on|off]
-chardev socket,id=id[,host=host],port=host[,to=to][,ipv4][,ipv6][,nodelay]
         [,server][,nowait][,telnet][,mux=on|off] (tcp)
-chardev socket,id=id,path=path[,server][,nowait][,telnet],[mux=on|off] (unix)
-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]
-chardev msmouse,id=id[,mux=on|off]
-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]
-chardev file,id=id,path=path[,mux=on|off]
-chardev pipe,id=id,path=path[,mux=on|off]
-chardev console,id=id[,mux=on|off]
-chardev serial,id=id,path=path[,mux=on|off]

Bluetooth(R) options:
-bt hci,null    dumb bluetooth HCI - doesn't respond to commands
-bt hci,host[:id]
                use host's HCI with the given name
-bt hci[,vlan=n]
                emulate a standard HCI in virtual scatternet 'n'
-bt vhci[,vlan=n]
                add host computer to virtual scatternet 'n' using VHCI
-bt device:dev[,vlan=n]
                emulate a bluetooth device 'dev' in scatternet 'n'

Linux/Multiboot boot specific:
-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 serial port to char device 'dev'
-parallel dev   redirect the parallel port to char device 'dev'
-monitor dev    redirect the monitor to char device 'dev'
-qmp dev        like -monitor but opens in 'control' mode
-mon chardev=[name][,mode=readline|control][,default]
-debugcon dev   redirect the debug console to char device 'dev'
-pidfile file   write PID to 'file'
-singlestep     always run in singlestep mode
-S              freeze CPU at startup (use 'c' to start execution)
-gdb dev        wait for gdb connection on 'dev'
-s              shorthand for -gdb tcp::1234
-d item1,...    output log to /tmp/qemu.log (use -d ? for a list of log items)
-D logfile      output log to logfile (instead of the default /tmp/qemu.log)
-hdachs c,h,s[,t]
                force hard disk 0 physical geometry and the optional BIOS
                translation (t=none or lba) (usually qemu can guess them)
-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
-xen-domid id   specify xen guest domain id
-xen-create     create domain using xen hypercalls, bypassing xend
                warning: should not be used when xend is in use
-xen-attach     attach to existing xen domain
                xend will use this when starting qemu
-no-reboot      exit instead of rebooting
-no-shutdown    stop before shutdown
-loadvm [tag|id]
                start right away with a saved state (loadvm in monitor)
-option-rom rom load a file, rom, into the option ROM space
-clock          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]
                set the RTC base and clock, enable drift fix for clock ticks (x86 only)
-icount [N|auto]
                enable virtual instruction counter with 2^N clock ticks per
-watchdog i6300esb|ib700
                enable virtual hardware watchdog [default=none]
-watchdog-action reset|shutdown|poweroff|pause|debug|none
                action when watchdog fires [default=reset]
-echr chr       set terminal escape character instead of ctrl-a
-virtioconsole c
                set virtio console
-show-cursor    show cursor
-tb-size n      set TB size
-incoming p     prepare for incoming migration, listen on port p
-nodefaults     don't create default devices
-prom-env variable=value
                set OpenBIOS nvram variables
-semihosting    semihosting mode
-old-param      old param mode
-readconfig <file>
-writeconfig <file>
                read/write config file
                do not load default config files at startup

During emulation, the following keys are useful:
ctrl-alt-f      toggle full screen
ctrl-alt-n      switch to virtual console 'n'
ctrl-alt        toggle mouse and keyboard grab

When using -nographic, press 'ctrl-a h' to get some help.

Qemu tutorials

So far we've setup the following tutorials suitable for Qemu:

See Also