--- name: "kvm-qemu" section: "1" platform: "linux" package: "kvm" version: "72+dfsg-5~lenny6" release: "Debian 5.0 (Lenny)" platforms: ["linux"] url: "https://new.carta.tech/kvm-qemu" --- # kvm-qemu(1) QEMU Emulator User Documentation ## 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/ISA PCI 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, ac97, 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. 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. General options: - **-M** *machine* Select the emulated *machine* (`"-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 **-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. - "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 "on" or "off" and allows to disable host cache to access data. - "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. - "boot=*boot*`"` *boot* if "on" enables extboot for a given drive so it can be used as a boot drive. 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 ``` To boot from a SCSI disk, one would use: ``` qemu -drive file=file,if=scsi,boot=on ``` 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 ``` - **-boot \[a\|c\|d\|n\]** Boot on floppy (a), hard disk (c), CD-ROM (d), or Etherboot (n). Hard disk boot is the default. - **-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**. - **-no-fd-bootchk** Disable boot signature checking for floppy disks in Bochs BIOS. It may be needed to boot from old floppy disks. - **-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. - **-smp** *n* 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. - **-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 hda qemu -soundhw es1370 hda qemu -soundhw ac97 hda qemu -soundhw all hda qemu -soundhw ? ``` Note that Linux's i810\_audio OSS kernel (for AC97) module might require manually specifying clocking. ``` modprobe i810_audio clocking=48000 ``` - **-localtime** 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. - **-startdate** *date* Set the initial date of the real time clock. Valid format for *date* are: `"now"` or `"2006-06-17T16:01:21"` or `"2006-06-17"`. The default value is `"now"`. - **-pidfile** *file* Store the QEMU process PID in *file*. It is useful if you launch QEMU from a script. - **-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. - **-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). - **-option-rom** *file* Load the contents of *file* as an option ROM. This option is useful to load things like EtherBoot. - **-name** *name* Sets the *name* of the guest. This name will be display in the SDL window caption. The *name* will also be used for the VNC server. 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. - **-no-quit** Disable SDL window close capability. - **-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. - **-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"`. 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:file" Mass storage device based on file - "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:nic\_num" Network adapter that supports CDC ethernet and RNDIS protocols. Network options: - **-net nic\[,vlan=***n***\]\[,macaddr=***addr***\]\[,model=***type***\]** Create a new Network Interface Card and connect it to VLAN *n* (*n* = 0 is the default). The NIC is an rtl8139 by default on the PC target. Optionally, the MAC address can be changed. 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 `"i82551"`, `"i82557b"`, `"i82559er"`, `"ne2k_pci"`, `"ne2k_isa"`, `"pcnet"`, `"rtl8139"`, `"e1000"`, `"smc91c111"`, `"lance"`, `"mcf_fec"` and `"usb"`. Not all devices are supported on all targets. Use -net nic,model=? for a list of available devices for your target. - **-net user\[,vlan=***n***\]\[,hostname=***name***\]** Use the user mode network stack which requires no administrator privilege to run. **hostname=name** can be used to specify the client hostname reported by the builtin DHCP server. - **-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*. Use **script=no** to disable script execution. 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=127.0.0.1:1234 ``` - **-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: - 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 **eth***N***=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\[,vlan=***n***\]\[,sock=***socketpath***\]\[,port=***n***\]\[,group=***groupname***\]\[,mode=***octalmode***\]** 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 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. - **-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). The host IP address on the guest is as usual 10.0.2.2. - **-bootp** *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 -tftp /path/to/tftp/files -bootp /pxelinux.0 ``` - **-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: ``` 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 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 10.0.2.15 (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 `"telnet 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 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 serials 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/parport*N*`"` \[Linux only, parallel port only\] 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* - "COM*n*`"` \[Windows only\] 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. - **-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. - **-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" - **-s** Wait gdb connection to port 1234. - **-p** *port* Change gdb connection port. *port* can be either a decimal number to specify a TCP port, or a host device (same devices as the serial port). - **-S** Do not start CPU at startup (you must type 'c' in the monitor). - **-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. - **-std-vga** Simulate a standard VGA card with Bochs VBE extensions (default is Cirrus Logic GD5446 PCI VGA). 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. - **-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-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) - **-semihosting** Enable semihosting syscall emulation (ARM and M68K target machines only). On ARM this implements the "Angel" interface. On M68K this implements the "ColdFire GDB" interface used by libgloss. Note that this allows guest direct access to the host filesystem, so should only be used with trusted guest OS. - **-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. During the graphical emulation, you can use the following keys: - **Ctrl-Alt-f** Toggle full screen - **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** 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. 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 \[SS-5\|SS-10\|SS-20\|SS-600MP\|SS-2\|SS-1000\|SS-2000\]** Set the emulated machine type. Default is SS-5. ## SEE ALSO The HTML documentation of QEMU for more precise information and Linux user mode emulator invocation. ## AUTHOR Fabrice Bellard