NAME

SYNOPSIS

DESCRIPTION

-

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

-

IPMI BMC, either and internal or external one

-

Creative SoundBlaster 16 sound card

-

ENSONIQ AudioPCI ES1370 sound card

-

Intel 82801AA AC97 Audio compatible sound card

-

Intel HD Audio Controller and HDA codec

-

Adlib (OPL2) - Yamaha YM3812 compatible chip

-

Gravis Ultrasound GF1 sound card

-

CS4231A compatible sound card

-

PCI UHCI, OHCI, EHCI or XHCI USB controller and a virtual USB-1.1 hub.

        qemu-system-i386 dos.img -soundhw gus -parallel none

        qemu-system-i386 dos.img -device gus,irq=5

OPTIONS

-h

Display help and exit

-version

Display version information and exit

-machine [type=]name[,prop=value [,...]]

Select the emulated machine by name. Use "-machine help" to list available machines.

 

For architectures which aim to support live migration compatibility across releases, each release will introduce a new versioned machine type. For example, the 2.8.0 release introduced machine types "pc-i440fx-2.8" and "pc-q35-2.8" for the x86_64/i686 architectures.

 

To allow live migration of guests from QEMU version 2.8.0, to QEMU version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8" and "pc-q35-2.8" machines too. To allow users live migrating VMs to skip multiple intermediate releases when upgrading, new releases of QEMU will support machine types from many previous versions.

 

Supported machine properties are:

-cpu model

Select CPU model ("-cpu help" for list and additional feature selection)

-accel name[,prop=value[,...]]

This is used to enable an accelerator. Depending on the target architecture, kvm, xen, hax or tcg can be available. By default, tcg is used. If there is more than one accelerator specified, the next one is used if the previous one fails to initialize.

-smp [cpus=]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 node[,mem=size][,cpus=firstcpu [-lastcpu ]][,nodeid=node]

-numa node[,memdev=id][,cpus=firstcpu [-lastcpu ]][,nodeid=node]

-numa dist,src=source,dst=destination ,val=distance

-numa cpu,node-id=node[,socket-id=x ][,core-id=y ][,thread-id=z]

Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA distance from a source node to a destination node.

 

Legacy VCPU assignment uses cpus option where firstcpu and lastcpu are CPU indexes. Each cpus option represent a contiguous range of CPU indexes (or a single VCPU if lastcpu is omitted). A non-contiguous set of VCPUs can be represented by providing multiple cpus options. If cpus is omitted on all nodes, VCPUs are automatically split between them.

 

For example, the following option assigns VCPUs 0, 1, 2 and 5 to a NUMA node:

 

        -numa node,cpus=0-2,cpus=5
    

 

cpu option is a new alternative to cpus option which uses socket-id|core-id|thread-id properties to assign CPU objects to a node using topology layout properties of CPU. The set of properties is machine specific, and depends on used machine type/ smp options. It could be queried with hotpluggable-cpus monitor command. node-id property specifies node to which CPU object will be assigned, it's required for node to be declared with node option before it's used with cpu option.

 

For example:

 

        -M pc \
        -smp 1,sockets=2,maxcpus=2 \
        -numa node,nodeid=0 -numa node,nodeid=1 \
        -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
    

 

mem assigns a given RAM amount to a node. memdev assigns RAM from a given memory backend device to a node. If mem and memdev are omitted in all nodes, RAM is split equally between them.

 

mem and memdev are mutually exclusive. Furthermore, if one node uses memdev, all of them have to use it.

 

source and destination are NUMA node IDs. distance is the NUMA distance from source to destination. The distance from a node to itself is always 10. If any pair of nodes is given a distance, then all pairs must be given distances. Although, when distances are only given in one direction for each pair of nodes, then the distances in the opposite directions are assumed to be the same. If, however, an asymmetrical pair of distances is given for even one node pair, then all node pairs must be provided distance values for both directions, even when they are symmetrical. When a node is unreachable from another node, set the pair's distance to 255.

 

Note that the - numa option doesn't allocate any of the specified resources, it just assigns existing resources to NUMA nodes. This means that one still has to use the -m, -smp options to allocate RAM and VCPUs respectively.

-add-fd fd=fd,set=set[,opaque= opaque]

Add a file descriptor to an fd set. Valid options are:

        qemu-system-i386
        -add-fd fd=3,set=2,opaque="rdwr:/path/to/file"
        -add-fd fd=4,set=2,opaque="rdonly:/path/to/file"
        -drive file=/dev/fdset/2,index=0,media=disk

-set group.id.arg=value

Set parameter arg for item id of type group

-global driver.prop=value

-global driver=driver,property=property ,value=value

Set default value of driver's property prop to value, e.g.:

 

        qemu-system-i386 -global ide-hd.physical_block_size=4096 disk-image.img
    

 

In particular, you can use this to set driver properties for devices which are created automatically by the machine model. To create a device which is not created automatically and set properties on it, use - device.

 

-global driver.prop=value is shorthand for -global driver= driver,property=prop,value=value. The longhand syntax works even when driver contains a dot.

-boot [order=drives][,once=drives ][,menu=on|off][,splash= sp_name][,splash-time=sp_time ][,reboot-timeout=rb_timeout][,strict=on|off]

Specify boot order drives as a string of drive letters. Valid drive letters depend on the target architecture. 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. Note that the order or once parameter should not be used together with the bootindex property of devices, since the firmware implementations normally do not support both at the same time.

 

Interactive boot menus/prompts can be enabled via menu=on as far as firmware/BIOS supports them. The default is non-interactive boot.

 

A splash picture could be passed to bios, enabling user to show it as logo, when option splash= sp_name is given and menu=on, If firmware/BIOS supports them. Currently Seabios for X86 system support it. limitation: The splash file could be a jpeg file or a BMP file in 24 BPP format(true color). The resolution should be supported by the SVGA mode, so the recommended is 320x240, 640x480, 800x640.

 

A timeout could be passed to bios, guest will pause for rb_timeout ms when boot failed, then reboot. If rb_timeout is '-1', guest will not reboot, qemu passes '-1' to bios by default. Currently Seabios for X86 system support it.

 

Do strict boot via strict=on as far as firmware/BIOS supports it. This only effects when boot priority is changed by bootindex options. The default is non-strict boot.

 

        # try to boot from network first, then from hard disk
        qemu-system-i386 -boot order=nc
        # boot from CD-ROM first, switch back to default order after reboot
        qemu-system-i386 -boot once=d
        # boot with a splash picture for 5 seconds.
        qemu-system-i386 -boot menu=on,splash=/root/boot.bmp,splash-time=5000
    

 

Note: The legacy format '-boot drives' is still supported but its use is discouraged as it may be removed from future versions.

-m [size=]megs[,slots=n,maxmem=size]

Sets guest startup 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. Optional pair slots, maxmem could be used to set amount of hotpluggable memory slots and maximum amount of memory. Note that maxmem must be aligned to the page size.

 

For example, the following command-line sets the guest startup RAM size to 1GB, creates 3 slots to hotplug additional memory and sets the maximum memory the guest can reach to 4GB:

 

        qemu-system-x86_64 -m 1G,slots=3,maxmem=4G
    

 

If slots and maxmem are not specified, memory hotplug won't be enabled and the guest startup RAM will never increase.

-mem-path path

Allocate guest RAM from a temporarily created file in path.

-mem-prealloc

Preallocate memory when using -mem-path.

-k language

Use keyboard layout language (for example "fr" for French). This option is only needed where it is not easy to get raw PC keycodes (e.g. on Macs, with some X11 servers or with a VNC or curses display). You don't normally need to use it on PC/Linux or PC/Windows hosts.

 

The available layouts are:

 

        ar  de-ch  es  fo     fr-ca  hu  ja  mk     no  pt-br  sv
        da  en-gb  et  fr     fr-ch  is  lt  nl     pl  ru     th
        de  en-us  fi  fr-be  hr     it  lv  nl-be  pt  sl     tr
    

 

The default is "en-us".

-audio-help

Will show the audio subsystem help: list of drivers, tunable parameters.

-soundhw card1[,card2,...] or -soundhw all

Enable audio and selected sound hardware. Use 'help' to print all available sound hardware.

 

        qemu-system-i386 -soundhw sb16,adlib disk.img
        qemu-system-i386 -soundhw es1370 disk.img
        qemu-system-i386 -soundhw ac97 disk.img
        qemu-system-i386 -soundhw hda disk.img
        qemu-system-i386 -soundhw all disk.img
        qemu-system-i386 -soundhw help
    

 

Note that Linux's i810_audio OSS kernel (for AC97) module might require manually specifying clocking.

 

        modprobe i810_audio clocking=48000
    

-balloon none

Disable balloon device.

-balloon virtio[,addr=addr]

Enable virtio balloon device (default), optionally with PCI address addr.

-device driver[,prop[=value][,...]]

Add device driver. prop=value sets driver properties. Valid properties depend on the driver. To get help on possible drivers and properties, use "-device help" and "-device driver,help".

 

Some drivers are:

-device ipmi-bmc-sim,id=id[,slave_addr= val][,sdrfile= file][,furareasize=val][,furdatafile= file ]

Add an IPMI BMC. This is a simulation of a hardware management interface processor that normally sits on a system. It provides a watchdog and the ability to reset and power control the system. You need to connect this to an IPMI interface to make it useful

 

The IPMI slave address to use for the BMC. The default is 0x20. This address is the BMC's address on the I2C network of management controllers. If you don't know what this means, it is safe to ignore it.

-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]

Add a connection to an external IPMI BMC simulator. Instead of locally emulating the BMC like the above item, instead connect to an external entity that provides the IPMI services.

 

A connection is made to an external BMC simulator. If you do this, it is strongly recommended that you use the "reconnect=" chardev option to reconnect to the simulator if the connection is lost. Note that if this is not used carefully, it can be a security issue, as the interface has the ability to send resets, NMIs, and power off the VM. It's best if QEMU makes a connection to an external simulator running on a secure port on localhost, so neither the simulator nor QEMU is exposed to any outside network.

 

See the "lanserv/README.vm" file in the OpenIPMI library for more details on the external interface.

-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]

Add a KCS IPMI interafce on the ISA bus. This also adds a corresponding ACPI and SMBIOS entries, if appropriate.

-device isa-ipmi-bt,bmc=id[,ioport=val ][,irq=val ]

Like the KCS interface, but defines a BT interface. The default port is 0xe4 and the default interrupt is 5.

-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. Naming of individual threads can also be enabled on Linux to aid debugging.

-uuid uuid

Set system UUID.

-fda file

-fdb file

Use file as floppy disk 0/1 image.

-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.

-blockdev option[,option[, option[,...]]]

Define a new block driver node. Some of the options apply to all block drivers, other options are only accepted for a specific block driver. See below for a list of generic options and options for the most common block drivers.

 

Options that expect a reference to another node (e.g. "file") can be given in two ways. Either you specify the node name of an already existing node (file= node-name), or you define a new node inline, adding options for the referenced node after a dot (file.filename= path,file.aio=native).

 

A block driver node created with -blockdev can be used for a guest device by specifying its node name for the "drive" property in a -device argument that defines a block device.

        -blockdev driver=file,node-name=disk,filename=disk.img

        -blockdev driver=file,node-name=disk_file,filename=disk.img
        -blockdev driver=raw,node-name=disk,file=disk_file

        -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img

        -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
        -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216

        -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2

-drive option[,option[,option[,...]]]

Define a new drive. This includes creating a block driver node (the backend) as well as a guest device, and is mostly a shortcut for defining the corresponding -blockdev and -device options.

 

-drive accepts all options that are accepted by -blockdev. In addition, it knows the following options:

        qemu-system-i386 -drive file=file,index=2,media=cdrom

        qemu-system-i386 -drive file=file,index=0,media=disk
        qemu-system-i386 -drive file=file,index=1,media=disk
        qemu-system-i386 -drive file=file,index=2,media=disk
        qemu-system-i386 -drive file=file,index=3,media=disk

        qemu-system-i386
        -add-fd fd=3,set=2,opaque="rdwr:/path/to/file"
        -add-fd fd=4,set=2,opaque="rdonly:/path/to/file"
        -drive file=/dev/fdset/2,index=0,media=disk

        qemu-system-i386 -drive file=file,if=ide,index=1,media=cdrom

        qemu-system-i386 -drive if=ide,index=1,media=cdrom

        qemu-system-i386 -drive file=file,index=0,if=floppy
        qemu-system-i386 -drive file=file,index=1,if=floppy

        qemu-system-i386 -drive file=a -drive file=b"

        qemu-system-i386 -hda a -hdb b

-mtdblock file

Use file as on-board Flash memory image.

-sd file

Use file as SecureDigital card image.

-pflash file

Use file as a parallel flash image.

-snapshot

Write to temporary files instead of disk image files. In this case, the raw disk image you use is not written back. You can however force the write back by pressing C-a s.

-hdachs c,h,s,[, t]

Force hard disk 0 physical geometry (1 <= c <= 16383, 1 <= h <= 16, 1 <= s <= 63) and optionally force the BIOS translation mode ( t=none, lba or auto). Usually QEMU can guess all those parameters. This option is deprecated, please use "-device ide-hd,cyls=c,heads=h,secs=s,..." instead.

-fsdev fsdriver,id=id,path= path,[security_model= security_model][,writeout=writeout][,readonly][,socket=socket|sock_fd=sock_fd][,fmode=fmode][,dmode=dmode]

Define a new file system device. Valid options are:

-device virtio-9p-pci,fsdev=id,mount_tag= mount_tag

Options for virtio-9p-pci driver are:

-virtfs fsdriver[,path=path],mount_tag= mount_tag[,security_model=security_model][,writeout=writeout][,readonly][,socket=socket|sock_fd=sock_fd][,fmode=fmode][,dmode=dmode]

The general form of a Virtual File system pass-through options are:

-virtfs_synth

Create synthetic file system image

-usb

Enable the USB driver (if it is not used by default yet).

-usbdevice devname

Add the USB device devname. Note that this option is deprecated, please use "-device usb-..." instead.

-display type

Select type of display to use. This option is a replacement for the old style -sdl/-curses/... options. Valid values for type are

-nographic

Normally, if QEMU is compiled with graphical window support, it displays output such as guest graphics, guest console, and the QEMU monitor in a window. 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 and muxed with the monitor (unless redirected elsewhere explicitly). Therefore, you can still use QEMU to debug a Linux kernel with a serial console. Use C-a h for help on switching between the console and monitor.

-curses

Normally, if QEMU is compiled with graphical window support, it displays output such as guest graphics, guest console, and the QEMU monitor in a window. With this option, QEMU can display the VGA output when in text mode using a curses/ncurses interface. Nothing is displayed in graphical mode.

-no-frame

Do not use decorations for SDL windows and start them using the whole available screen space. This makes the using QEMU in a dedicated desktop workspace more convenient.

-alt-grab

Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that this also affects the special keys (for fullscreen, monitor-mode switching, etc).

-ctrl-grab

Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this also affects the special keys (for fullscreen, monitor-mode switching, etc).

-no-quit

Disable SDL window close capability.

-sdl

Enable SDL.

-spice option[,option[,...]]

Enable the spice remote desktop protocol. Valid options are

-portrait

Rotate graphical output 90 deg left (only PXA LCD).

-rotate deg

Rotate graphical output some deg left (only PXA LCD).

-vga type

Select type of VGA card to emulate. Valid values for type are

-full-screen

Start in full screen.

-g widthxheight[xdepth ]

Set the initial graphical resolution and depth (PPC, SPARC only).

-vnc display[,option[,option[,...]]]

Normally, if QEMU is compiled with graphical window support, it displays output such as guest graphics, guest console, and the QEMU monitor in a window. 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 -device usb-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

-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 BIOS. 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.

-acpitable [sig=str][,rev=n][,oem_id= str][,oem_table_id= str][,oem_rev=n] [,asl_compiler_id= str][,asl_compiler_rev=n][,data= file1[: file2]...]

Add ACPI table with specified header fields and context from specified files. For file=, take whole ACPI table from the specified files, including all ACPI headers (possible overridden by other options). For data=, only data portion of the table is used, all header information is specified in the command line. If a SLIC table is supplied to QEMU, then the SLIC's oem_id and oem_table_id fields will override the same in the RSDT and the FADT (a.k.a. FACP), in order to ensure the field matches required by the Microsoft SLIC spec and the ACPI spec.

-smbios file=binary

Load SMBIOS entry from binary file.

-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]

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

-smbios type=2[,manufacturer=str][,product= str][,version= str][,serial=str][,asset= str][,location= str][,family=str]

Specify SMBIOS type 2 fields

-smbios type=3[,manufacturer=str][,version= str][,serial= str][,asset=str][,sku= str]

Specify SMBIOS type 3 fields

-smbios type=4[,sock_pfx=str][,manufacturer= str][,version= str][,serial=str][,asset= str][,part= str]

Specify SMBIOS type 4 fields

-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]

Specify SMBIOS type 17 fields

-net nic[,vlan=n][,macaddr=mac][,model=type] [,name= name][,addr=addr][,vectors=v]

Create a new Network Interface Card and connect it to VLAN n (n = 0 is the default). The NIC is an e1000 by default on the PC target. Optionally, the MAC address can be changed to mac, the device address set to addr (PCI cards only), and a name can be assigned for use in monitor commands. Optionally, for PCI cards, you can specify the number v of MSI-X vectors that the card should have; this option currently only affects virtio cards; set v = 0 to disable MSI-X. If no -net option is specified, a single NIC is created. QEMU can emulate several different models of network card. Valid values for type are "virtio", "i82551", "i82557b", "i82559er", "ne2k_pci", "ne2k_isa", "pcnet", "rtl8139", "e1000", "smc91c111", "lance" and "mcf_fec". Not all devices are supported on all targets. Use "-net nic,model=help" for a list of available devices for your target.

-netdev user,id=id[,option][, option][,...]

-net user[,option][,option][,...]

Use the user mode network stack which requires no administrator privilege to run. Valid options are:

-netdev tap,id=id[,fd=h][,ifname= name][,script= file][,downscript=dfile][,br= bridge][,helper= helper]

-net tap[,vlan=n][,name=name][,fd= h][,ifname= name][,script=file][,downscript= dfile][,br= bridge][,helper=helper]

Connect the host TAP network interface name to VLAN n.

 

Use the network script file to configure it and the network script dfile to deconfigure it. If name is not provided, the OS automatically provides one. The default network configure script is /etc/qemu-ifup and the default network deconfigure script is /etc/qemu-ifdown. Use script=no or downscript=no to disable script execution.

 

If running QEMU as an unprivileged user, use the network helper helper to configure the TAP interface and attach it to the bridge. The default network helper executable is /path/to/qemu-bridge-helper and the default bridge device is br0.

 

fd=h can be used to specify the handle of an already opened host TAP interface.

 

Examples:

 

        #launch a QEMU instance with the default network script
        qemu-system-i386 linux.img -net nic -net tap
        
        #launch a QEMU instance with two NICs, each one connected
        #to a TAP device
        qemu-system-i386 linux.img \
        -net nic,vlan=0 -net tap,vlan=0,ifname=tap0 \
        -net nic,vlan=1 -net tap,vlan=1,ifname=tap1
        
        #launch a QEMU instance with the default network helper to
        #connect a TAP device to bridge br0
        qemu-system-i386 linux.img \
        -net nic -net tap,"helper=/path/to/qemu-bridge-helper"
    

-netdev bridge,id=id[,br=bridge][,helper=helper]

-net bridge[,vlan=n][,name=name][,br=bridge][,helper=helper]

Connect a host TAP network interface to a host bridge device.

 

Use the network helper helper to configure the TAP interface and attach it to the bridge. The default network helper executable is /path/to/qemu-bridge-helper and the default bridge device is br0.

 

Examples:

 

        #launch a QEMU instance with the default network helper to
        #connect a TAP device to bridge br0
        qemu-system-i386 linux.img -net bridge -net nic,model=virtio
        
        #launch a QEMU instance with the default network helper to
        #connect a TAP device to bridge qemubr0
        qemu-system-i386 linux.img -net bridge,br=qemubr0 -net nic,model=virtio
    

-netdev socket,id=id[,fd=h][,listen=[ host]: port][,connect=host:port ]

-net socket[,vlan=n][,name=name][,fd=h] [,listen=[ host]:port][,connect=host:port]

Connect the VLAN n to a remote VLAN in another QEMU virtual machine using a TCP socket connection. If listen is specified, QEMU waits for incoming connections on port ( host is optional). connect is used to connect to another QEMU instance using the listen option. fd=h specifies an already opened TCP socket.

 

Example:

 

        # launch a first QEMU instance
        qemu-system-i386 linux.img \
        -net nic,macaddr=52:54:00:12:34:56 \
        -net socket,listen=:1234
        # connect the VLAN 0 of this instance to the VLAN 0
        # of the first instance
        qemu-system-i386 linux.img \
        -net nic,macaddr=52:54:00:12:34:57 \
        -net socket,connect=127.0.0.1:1234
    

-netdev socket,id=id[,fd=h][,mcast= maddr: port[,localaddr=addr]]

-net socket[,vlan=n][,name=name][,fd=h][,mcast=maddr:port[,localaddr=addr]]

Create a VLAN n shared with another QEMU virtual machines using a UDP multicast socket, effectively making a bus for every QEMU with same multicast address maddr and port. NOTES:

        # launch one QEMU instance
        qemu-system-i386 linux.img \
        -net nic,macaddr=52:54:00:12:34:56 \
        -net socket,mcast=230.0.0.1:1234
        # launch another QEMU instance on same "bus"
        qemu-system-i386 linux.img \
        -net nic,macaddr=52:54:00:12:34:57 \
        -net socket,mcast=230.0.0.1:1234
        # launch yet another QEMU instance on same "bus"
        qemu-system-i386 linux.img \
        -net nic,macaddr=52:54:00:12:34:58 \
        -net socket,mcast=230.0.0.1:1234

        # launch QEMU instance (note mcast address selected
        # is UML's default)
        qemu-system-i386 linux.img \
        -net nic,macaddr=52:54:00:12:34:56 \
        -net socket,mcast=239.192.168.1:1102
        # launch UML
        /path/to/linux ubd0=/path/to/root_fs eth0=mcast

        qemu-system-i386 linux.img \
        -net nic,macaddr=52:54:00:12:34:56 \
        -net socket,mcast=239.192.168.1:1102,localaddr=1.2.3.4

-netdev l2tpv3,id=id,src=srcaddr ,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]

-net l2tpv3[,vlan=n][,name=name],src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]

Connect VLAN n to L2TPv3 pseudowire. L2TPv3 (RFC3391) is a popular protocol to transport Ethernet (and other Layer 2) data frames between two systems. It is present in routers, firewalls and the Linux kernel (from version 3.3 onwards).

 

This transport allows a VM to communicate to another VM, router or firewall directly.

src=srcaddr

source address (mandatory)

dst=dstaddr

destination address (mandatory)

udp

select udp encapsulation (default is ip).

srcport=srcport

source udp port.

dstport=dstport

destination udp port.

ipv6

force v6, otherwise defaults to v4.

rxcookie=rxcookie

txcookie=txcookie

Cookies are a weak form of security in the l2tpv3 specification. Their function is mostly to prevent misconfiguration. By default they are 32 bit.

cookie64

Set cookie size to 64 bit instead of the default 32

counter=off

Force a 'cut-down' L2TPv3 with no counter as in draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00

pincounter=on

Work around broken counter handling in peer. This may also help on networks which have packet reorder.

offset=offset

Add an extra offset between header and data

 

For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to the bridge br-lan on the remote Linux host 1.2.3.4:

 

        # Setup tunnel on linux host using raw ip as encapsulation
        # on 1.2.3.4
        ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \
        encap udp udp_sport 16384 udp_dport 16384
        ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \
        0xFFFFFFFF peer_session_id 0xFFFFFFFF
        ifconfig vmtunnel0 mtu 1500
        ifconfig vmtunnel0 up
        brctl addif br-lan vmtunnel0
        
        
        # on 4.3.2.1
        # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
        
        qemu-system-i386 linux.img -net nic -net l2tpv3,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
    

-netdev vde,id=id[,sock=socketpath ][,port=n][,group=groupname][,mode=octalmode]

-net vde[,vlan=n][,name=name][,sock= socketpath ] [,port=n][,group=groupname][,mode=octalmode]

Connect VLAN n to PORT n of a vde switch running on host and listening for incoming connections on socketpath. Use GROUP groupname and MODE octalmode to change default ownership and permissions for communication port. This option is only available if QEMU has been compiled with vde support enabled.

 

Example:

 

        # launch vde switch
        vde_switch -F -sock /tmp/myswitch
        # launch QEMU instance
        qemu-system-i386 linux.img -net nic -net vde,sock=/tmp/myswitch
    

-netdev hubport,id=id,hubid=hubid

Create a hub port on QEMU "vlan" hubid.

 

The hubport netdev lets you connect a NIC to a QEMU "vlan" instead of a single netdev. "-net" and "-device" with parameter vlan create the required hub automatically.

-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]

Establish a vhost-user netdev, backed by a chardev id. The chardev should be a unix domain socket backed one. The vhost-user uses a specifically defined protocol to pass vhost ioctl replacement messages to an application on the other end of the socket. On non-MSIX guests, the feature can be forced with vhostforce. Use 'queues= n' to specify the number of queues to be created for multiqueue vhost-user.

 

Example:

 

        qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
        -numa node,memdev=mem \
        -chardev socket,id=chr0,path=/path/to/socket \
        -netdev type=vhost-user,id=net0,chardev=chr0 \
        -device virtio-net-pci,netdev=net0
    

-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. Note: For devices created with '-netdev', use '-object filter-dump,...' instead.

-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.

-chardev backend ,id=id [,mux=on|off] [, options]

Backend is one of: null, socket, udp, msmouse, vc, ringbuf, file, pipe, console, serial, pty, stdio, braille, tty, parallel, parport, spicevmc. spiceport. The specific backend will determine the applicable options.

 

Use "-chardev help" to print all available chardev backend types.

 

All devices must have an id, which can be any string up to 127 characters long. It is used to uniquely identify this device in other command line directives.

 

A character device may be used in multiplexing mode by multiple front-ends. Specify mux=on to enable this mode. A multiplexer is a "1:N" device, and here the "1" end is your specified chardev backend, and the "N" end is the various parts of QEMU that can talk to a chardev. If you create a chardev with id=myid and mux=on, QEMU will create a multiplexer with your specified ID, and you can then configure multiple front ends to use that chardev ID for their input/output. Up to four different front ends can be connected to a single multiplexed chardev. (Without multiplexing enabled, a chardev can only be used by a single front end.) For instance you could use this to allow a single stdio chardev to be used by two serial ports and the QEMU monitor:

 

        -chardev stdio,mux=on,id=char0 \
        -mon chardev=char0,mode=readline \
        -serial chardev:char0 \
        -serial chardev:char0
    

 

You can have more than one multiplexer in a system configuration; for instance you could have a TCP port multiplexed between UART 0 and UART 1, and stdio multiplexed between the QEMU monitor and a parallel port:

 

        -chardev stdio,mux=on,id=char0 \
        -mon chardev=char0,mode=readline \
        -parallel chardev:char0 \
        -chardev tcp,...,mux=on,id=char1 \
        -serial chardev:char1 \
        -serial chardev:char1
    

 

When you're using a multiplexed character device, some escape sequences are interpreted in the input.

 

Note that some other command line options may implicitly create multiplexed character backends; for instance -serial mon:stdio creates a multiplexed stdio backend connected to the serial port and the QEMU monitor, and -nographic also multiplexes the console and the monitor to stdio.

 

There is currently no support for multiplexing in the other direction (where a single QEMU front end takes input and output from multiple chardevs).

 

Every backend supports the logfile option, which supplies the path to a file to record all data transmitted via the backend. The logappend option controls whether the log file will be truncated or appended to when opened.

 

Further 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] [,reconnect= seconds] [,tls-creds=id]

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.

 

reconnect sets the timeout for reconnecting on non-server sockets when the remote end goes away. qemu will delay this many seconds and then attempt to reconnect. Zero disables reconnecting, and is the default.

 

tls-creds requests enablement of the TLS protocol for encryption, and specifies the id of the TLS credentials to use for the handshake. The credentials must be previously created with the -object tls-creds argument.

 

TCP and unix socket options are given below:

-chardev udp ,id=id [,host=host] ,port=port [,localaddr=localaddr ] [,localport=localport] [,ipv4] [,ipv6]

Sends all traffic from the guest to a remote host over UDP.

 

host specifies the remote host to connect to. If not specified it defaults to "localhost".

 

port specifies the port on the remote host to connect to. port is required.

 

localaddr specifies the local address to bind to. If not specified it defaults to 0.0.0.0.

 

localport specifies the local port to bind to. If not specified any available local port will be used.

 

ipv4 and ipv6 specify that either IPv4 or IPv6 must be used. If neither is specified the device may use either protocol.

-chardev msmouse ,id=id

Forward QEMU's emulated msmouse events to the guest. msmouse does not take any options.

-chardev vc ,id=id [[,width=width ] [,height=height]] [[,cols= cols] [,rows=rows]]

Connect to a QEMU text console. vc may optionally be given a specific size.

 

width and height specify the width and height respectively of the console, in pixels.

 

cols and rows specify that the console be sized to fit a text console with the given dimensions.

-chardev ringbuf ,id=id [,size=size ]

Create a ring buffer with fixed size size. size must be a power of two and defaults to "64K".

-chardev file ,id=id ,path=path

Log all traffic received from the guest to a file.

 

path specifies the path of the file to be opened. This file will be created if it does not already exist, and overwritten if it does. path is required.

-chardev pipe ,id=id ,path=path

Create a two-way connection to the guest. The behaviour differs slightly between Windows hosts and other hosts:

 

On Windows, a single duplex pipe will be created at \\.pipe\path .

 

On other hosts, 2 pipes will be created called path.in and path.out. Data written to path .in will be received by the guest. Data written by the guest can be read from path.out. QEMU will not create these fifos, and requires them to be present.

 

path forms part of the pipe path as described above. path is required.

-chardev console ,id=id

Send traffic from the guest to QEMU's standard output. console does not take any options.

 

console is only available on Windows hosts.

-chardev serial ,id=id ,path=path

Send traffic from the guest to a serial device on the host.

 

On Unix hosts serial will actually accept any tty device, not only serial lines.

 

path specifies the name of the serial device to open.

-chardev pty ,id=id

Create a new pseudo-terminal on the host and connect to it. pty does not take any options.

 

pty is not available on Windows hosts.

-chardev stdio ,id=id [,signal=on|off]

Connect to standard input and standard output of the QEMU process.

 

signal controls if signals are enabled on the terminal, that includes exiting QEMU with the key sequence Control-c. This option is enabled by default, use signal=off to disable it.

-chardev braille ,id=id

Connect to a local BrlAPI server. braille does not take any options.

-chardev tty ,id=id ,path=path

tty is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD and DragonFlyBSD hosts. It is an alias for serial.

 

path specifies the path to the tty. path is required.

-chardev parallel ,id=id ,path=path

-chardev parport ,id=id ,path=path

parallel is only available on Linux, FreeBSD and DragonFlyBSD hosts.

 

Connect to a local parallel port.

 

path specifies the path to the parallel port device. path is required.

-chardev spicevmc ,id=id ,debug=debug , name=name

spicevmc is only available when spice support is built in.

 

debug debug level for spicevmc

 

name name of spice channel to connect to

 

Connect to a spice virtual machine channel, such as vdiport.

-chardev spiceport ,id=id ,debug=debug , name=name

spiceport is only available when spice support is built in.

 

debug debug level for spicevmc

 

name name of spice port to connect to

 

Connect to a spice port, allowing a Spice client to handle the traffic identified by a name (preferably a fqdn).

iSCSI

iSCSI support allows QEMU to access iSCSI resources directly and use as images for the guest storage. Both disk and cdrom images are supported.

 

Syntax for specifying iSCSI LUNs is "iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>"

 

By default qemu will use the iSCSI initiator-name 'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command line or a configuration file.

 

Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect stalled requests and force a reestablishment of the session. The timeout is specified in seconds. The default is 0 which means no timeout. Libiscsi 1.15.0 or greater is required for this feature.

 

Example (without authentication):

 

        qemu-system-i386 -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \
        -cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \
        -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
    

 

Example (CHAP username/password via URL):

 

        qemu-system-i386 -drive file=iscsi://user%password@192.0.2.1/iqn.2001-04.com.example/1
    

 

Example (CHAP username/password via environment variables):

 

        LIBISCSI_CHAP_USERNAME="user" \
        LIBISCSI_CHAP_PASSWORD="password" \
        qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
    

 

iSCSI support is an optional feature of QEMU and only available when compiled and linked against libiscsi.

 

iSCSI parameters such as username and password can also be specified via a configuration file. See qemu-doc for more information and examples.

NBD

QEMU supports NBD (Network Block Devices) both using TCP protocol as well as Unix Domain Sockets.

 

Syntax for specifying a NBD device using TCP "nbd:<server-ip>:<port>[:exportname=<export>]"

 

Syntax for specifying a NBD device using Unix Domain Sockets "nbd:unix:<domain-socket>[:exportname=<export>]"

 

Example for TCP

 

        qemu-system-i386 --drive file=nbd:192.0.2.1:30000
    

 

Example for Unix Domain Sockets

 

        qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket
    

SSH

QEMU supports SSH (Secure Shell) access to remote disks.

 

Examples:

 

        qemu-system-i386 -drive file=ssh://user@host/path/to/disk.img
        qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
    

 

Currently authentication must be done using ssh-agent. Other authentication methods may be supported in future.

Sheepdog

Sheepdog is a distributed storage system for QEMU. QEMU supports using either local sheepdog devices or remote networked devices.

 

Syntax for specifying a sheepdog device

 

        sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]
    

 

Example

 

        qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
    

 

See also < https://sheepdog.github.io/sheepdog/>.

GlusterFS

GlusterFS is a user space distributed file system. QEMU supports the use of GlusterFS volumes for hosting VM disk images using TCP, Unix Domain Sockets and RDMA transport protocols.

 

Syntax for specifying a VM disk image on GlusterFS volume is

 

        URI:
        gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...]
        
        JSON:
        'json:{"driver":"qcow2","file":{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...",
                                         "server":[{"type":"tcp","host":"...","port":"..."},
                                                   {"type":"unix","socket":"..."}]}}'
    

 

Example

 

        URI:
        qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img,
                                       file.debug=9,file.logfile=/var/log/qemu-gluster.log
        
        JSON:
        qemu-system-x86_64 'json:{"driver":"qcow2",
                                  "file":{"driver":"gluster",
                                           "volume":"testvol","path":"a.img",
                                           "debug":9,"logfile":"/var/log/qemu-gluster.log",
                                           "server":[{"type":"tcp","host":"1.2.3.4","port":24007},
                                                     {"type":"unix","socket":"/var/run/glusterd.socket"}]}}'
        qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
                                              file.debug=9,file.logfile=/var/log/qemu-gluster.log,
                                              file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
                                              file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
    

 

See also < http://www.gluster.org>.

HTTP/HTTPS/FTP/FTPS

QEMU supports read-only access to files accessed over http(s) and ftp(s).

 

Syntax using a single filename:

 

        <protocol>://[<username>[:<password>]@]<host>/<path>
    

 

where:

        qemu-system-x86_64 --drive media=cdrom,file=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
        
        qemu-system-x86_64 --drive media=cdrom,file.driver=http,file.url=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly

        qemu-img create -f qcow2 -o backing_file='json:{"file.driver":"http",, "file.url":"https://dl.fedoraproject.org/pub/fedora/linux/releases/20/Images/x86_64/Fedora-x86_64-20-20131211.1-sda.qcow2",, "file.readahead":"64k"}' /tmp/Fedora-x86_64-20-20131211.1-sda.qcow2
        
        qemu-system-x86_64 -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on

        qemu-img create -f qcow2 -o backing_file='json:{"file.driver":"https",, "file.url":"https://user:password@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k",, "file.timeout":10}' /tmp/test.qcow2
        
        qemu-system-x86_64 -drive file=/tmp/test.qcow2

-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 vhci[,vlan=n]

(Linux-host only) Create a HCI in scatternet n (default 0) attached to the host bluetooth stack instead of to the emulated target. This allows the host and target machines to participate in a common scatternet and communicate. Requires the Linux "vhci" driver installed. Can be used as following:

 

        qemu-system-i386 [...OPTIONS...] -bt hci,vlan=5 -bt vhci,vlan=5
    

-bt device:dev[,vlan=n]

Emulate a bluetooth device dev and place it in network n (default 0). QEMU can only emulate one type of bluetooth devices currently:

-tpmdev backend ,id=id [, options]

Backend type must be either one of the following: passthrough, emulator.

 

The specific backend type will determine the applicable options. The "-tpmdev" option creates the TPM backend and requires a "-device" option that specifies the TPM frontend interface model.

 

Options to each backend are described below.

 

Use 'help' to print all available TPM backend types.

 

        qemu -tpmdev help
    

-tpmdev passthrough, id=id, path=path , cancel-path=cancel-path

(Linux-host only) Enable access to the host's TPM using the passthrough driver.

 

path specifies the path to the host's TPM device, i.e., on a Linux host this would be "/dev/tpm0". path is optional and by default "/dev/tpm0" is used.

 

cancel-path specifies the path to the host TPM device's sysfs entry allowing for cancellation of an ongoing TPM command. cancel-path is optional and by default QEMU will search for the sysfs entry to use.

 

Some notes about using the host's TPM with the passthrough driver:

 

The TPM device accessed by the passthrough driver must not be used by any other application on the host.

 

Since the host's firmware (BIOS/UEFI) has already initialized the TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize the TPM again and may therefore not show a TPM-specific menu that would otherwise allow the user to configure the TPM, e.g., allow the user to enable/disable or activate/deactivate the TPM. Further, if TPM ownership is released from within a VM then the host's TPM will get disabled and deactivated. To enable and activate the TPM again afterwards, the host has to be rebooted and the user is required to enter the firmware's menu to enable and activate the TPM. If the TPM is left disabled and/or deactivated most TPM commands will fail.

 

To create a passthrough TPM use the following two options:

 

        -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
    

 

Note that the "-tpmdev" id is "tpm0" and is referenced by "tpmdev=tpm0" in the device option.

-tpmdev emulator, id=id, chardev=dev

(Linux-host only) Enable access to a TPM emulator using Unix domain socket based chardev backend.

 

chardev specifies the unique ID of a character device backend that provides connection to the software TPM server.

 

To create a TPM emulator backend device with chardev socket backend:

 

        -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
    

-kernel bzImage

Use bzImage as kernel image. The kernel can be either a Linux kernel or in multiboot format.

-append cmdline

Use cmdline as kernel command line

-initrd file

Use file as initial ram disk.

-initrd "file1 arg=foo,file2 "

This syntax is only available with multiboot.

 

Use file1 and file2 as modules and pass arg=foo as parameter to the first module.

-dtb file

Use file as a device tree binary (dtb) image and pass it to the kernel on boot.

-fw_cfg [name=]name,file=file

Add named fw_cfg entry with contents from file file.

-fw_cfg [name=]name,string=str

Add named fw_cfg entry with contents from string str.

 

The terminating NUL character of the contents of str will not be included as part of the fw_cfg item data. To insert contents with embedded NUL characters, you have to use the file parameter.

 

The fw_cfg entries are passed by QEMU through to the guest.

 

Example:

 

        -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
    

 

creates an fw_cfg entry named opt/com.mycompany/blob with contents from ./my_blob.bin.

-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:

-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. Use "-monitor none" to disable the default monitor.

-qmp dev

Like -monitor but opens in 'control' mode.

-qmp-pretty dev

Like -qmp but uses pretty JSON formatting.

-mon [chardev=]name[,mode=readline|control]

Setup monitor on chardev name.

-debugcon dev

Redirect the debug console to host device dev (same devices as the serial port). The debug console is an I/O port which is typically port 0xe9; writing to that I/O port sends output to this device. The default device is "vc" in graphical mode and "stdio" in non graphical mode.

-pidfile file

Store the QEMU process PID in file. It is useful if you launch QEMU from a script.

-singlestep

Run the emulation in single step mode.

-S

Do not start CPU at startup (you must type 'c' in the monitor).

-realtime mlock=on|off

Run qemu with realtime features. mlocking qemu and guest memory can be enabled via mlock=on (enabled by default).

-gdb dev

Wait for gdb connection on device dev. Typical connections will likely be TCP-based, but also UDP, pseudo TTY, or even stdio are reasonable use case. The latter is allowing to start QEMU from within gdb and establish the connection via a pipe:

 

        (gdb) target remote | exec qemu-system-i386 -gdb stdio ...
    

-s

Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234.

-d item1[,...]

Enable logging of specified items. Use '-d help' for a list of log items.

-D logfile

Output log in logfile instead of to stderr

-dfilter range1[,...]

Filter debug output to that relevant to a range of target addresses. The filter spec can be either start+size, start- size or start..end where start end and size are the addresses and sizes required. For example:

 

        -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
    

 

Will dump output for any code in the 0x1000 sized block starting at 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and another 0x1000 sized block starting at 0xffffffc00005f000.

-L path

Set the directory for the BIOS, VGA BIOS and keymaps.

 

To list all the data directories, use "-L help".

-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.

-enable-hax

Enable HAX (Hardware-based Acceleration eXecution) support. This option is only available if HAX support is enabled when compiling. HAX is only applicable to MAC and Windows platform, and thus does not conflict with KVM.

-xen-domid id

Specify xen guest domain id (XEN only).

-xen-create

Create domain using xen hypercalls, bypassing xend. Warning: should not be used when xend is in use (XEN only).

-xen-attach

Attach to existing xen domain. xend will use this when starting QEMU (XEN only). Restrict set of available xen operations to specified domain id (XEN only).

-no-reboot

Exit instead of rebooting.

-no-shutdown

Don't exit QEMU on guest shutdown, but instead only stop the emulation. This allows for instance switching to monitor to commit changes to the disk image.

-loadvm file

Start right away with a saved state ("loadvm" in monitor)

-daemonize

Daemonize the QEMU process after initialization. QEMU will not detach from standard IO until it is ready to receive connections on any of its devices. This option is a useful way for external programs to launch QEMU without having to cope with initialization race conditions.

-option-rom file

Load the contents of file as an option ROM. This option is useful to load things like EtherBoot.

-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 using of the RTC as accurate reference clock inside the guest, specifically if the host time is smoothly following an accurate external reference clock, e.g. via NTP. If you want to isolate the guest time from the host, you can set clock to "rt" instead. To even prevent it from progressing during suspension, you can set it to "vm".

 

Enable driftfix (i386 targets only) if you experience time drift problems, specifically with Windows' ACPI HAL. This option will try to figure out how many timer interrupts were not processed by the Windows guest and will re-inject them.

-icount [shift=N|auto][,rr=record|replay,rrfile= filename,rrsnapshot=snapshot]

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.

 

When the virtual cpu is sleeping, the virtual time will advance at default speed unless sleep=on|off is specified. With sleep=on|off, the virtual time will jump to the next timer deadline instantly whenever the virtual cpu goes to sleep mode and will not advance if no timer is enabled. This behavior give deterministic execution times from the guest point of view.

 

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.

 

align=on will activate the delay algorithm which will try to synchronise the host clock and the virtual clock. The goal is to have a guest running at the real frequency imposed by the shift option. Whenever the guest clock is behind the host clock and if align=on is specified then we print a message to the user to inform about the delay. Currently this option does not work when shift is "auto". Note: The sync algorithm will work for those shift values for which the guest clock runs ahead of the host clock. Typically this happens when the shift value is high (how high depends on the host machine).

 

When rr option is specified deterministic record/replay is enabled. Replay log is written into filename file in record mode and read from this file in replay mode.

 

Option rrsnapshot is used to create new vm snapshot named snapshot at the start of execution recording. In replay mode this option is used to load the initial VM state.

-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. Choose a model for which your guest has drivers.

 

The model is the model of hardware watchdog to emulate. Use "-watchdog help" to list available hardware models. Only one watchdog can be enabled for a guest.

 

The following models may be available:

-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:

-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.

-virtioconsole c

Set virtio console.

 

This option is maintained for backward compatibility.

 

Please use "-device virtconsole" for the new way of invocation.

-show-cursor

Show cursor.

-tb-size n

Set TB size.

-incoming tcp:[host]:port[,to= maxport][,ipv4][,ipv6]

-incoming rdma:host:port[,ipv4][,ipv6]

Prepare for incoming migration, listen on a given tcp port.

-incoming unix:socketpath

Prepare for incoming migration, listen on a given unix socket.

-incoming fd:fd

Accept incoming migration from a given filedescriptor.

-incoming exec:cmdline

Accept incoming migration as an output from specified external command.

-incoming defer

Wait for the URI to be specified via migrate_incoming. The monitor can be used to change settings (such as migration parameters) prior to issuing the migrate_incoming to allow the migration to begin.

-only-migratable

Only allow migratable devices. Devices will not be allowed to enter an unmigratable state.

-nodefaults

Don't create default devices. Normally, QEMU sets the default devices like serial port, parallel port, virtual console, monitor device, VGA adapter, floppy and CD-ROM drive and others. The "-nodefaults" option will disable all those default devices.

-chroot dir

Immediately before starting guest execution, chroot to the specified directory. Especially useful in combination with -runas.

-runas user

Immediately before starting guest execution, drop root privileges, switching to the specified user.

-prom-env variable=value

Set OpenBIOS nvram variable to given value (PPC, SPARC only).

-semihosting

Enable semihosting mode (ARM, M68K, Xtensa, MIPS only).

-semihosting-config [enable=on|off][,target=native|gdb|auto][,arg=str[,...]]

Enable and configure semihosting (ARM, M68K, Xtensa, MIPS only).

-old-param

Old param mode (ARM only).

-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]

Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will disable it. The default is 'off'.

-readconfig file

Read device configuration from file. This approach is useful when you want to spawn QEMU process with many command line options but you don't want to exceed the command line character limit.

-writeconfig file

Write device configuration to file. The file can be either filename to save command line and device configuration into file or dash "-") character to print the output to stdout. This can be later used as input file for "-readconfig" option.

-no-user-config

The "-no-user-config" option makes QEMU not load any of the user-provided config files on sysconfdir.

-trace [[enable=]pattern][,events=file ][,file=file ]

Specify tracing options.

-enable-fips

Enable FIPS 140-2 compliance mode.

-msg timestamp[=on|off]

prepend a timestamp to each log message.(default:on)

-dump-vmstate file

Dump json-encoded vmstate information for current machine type to file in file

-object typename[,prop1=value1,...]

Create a new object of type typename setting properties in the order they are specified. Note that the 'id' property must be set. These objects are placed in the '/objects' path.

Ctrl-Alt-f

Toggle full screen

Ctrl-Alt-+

Enlarge the screen

Ctrl-Alt--

Shrink the screen

Ctrl-Alt-u

Restore the screen's un-scaled dimensions

Ctrl-Alt-n

Switch to virtual console 'n'. Standard console mappings are:

Ctrl-Alt

Toggle mouse and keyboard grab.

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

Rotate between the frontends connected to the multiplexer (usually this switches between the monitor and the console)

Ctrl-a Ctrl-a

Send the escape character to the frontend

-g WxH[xDEPTH]

Set the initial VGA graphic mode. The default is 800x600x32.

-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.

-g WxHx[xDEPTH]

Set the initial graphics mode. For TCX, the default is 1024x768x8 with the option of 1024x768x24. For cgthree, the default is 1024x768x8 with the option of 1152x900x8 for people who wish to use OBP.

-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]

Set the emulated machine type. Default is SS-5.

-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.

-semihosting

Enable semihosting syscall emulation.

 

On ARM this implements the "Angel" interface.

 

Note that this allows guest direct access to the host filesystem, so should only be used with trusted guest OS.

-semihosting

Enable semihosting syscall emulation.

 

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.

-semihosting

Enable semihosting syscall emulation.

 

Xtensa semihosting provides basic file IO calls, such as open/read/write/seek/select. Tensilica baremetal libc for ISS and linux platform "sim" use this interface.

 

Note that this allows guest direct access to the host filesystem, so should only be used with trusted guest OS.

SEE ALSO

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