qemu(1)



QEMU(1)                              QEMU                              QEMU(1)

NAME
       qemu - QEMU User Documentation

SYNOPSIS
          qemu-system-x86_64 [options] [disk_image]

DESCRIPTION
       The QEMU PC System emulator simulates the following peripherals:

       o i440FX host PCI bridge and PIIX3 PCI to ISA bridge

       o Cirrus  CLGD  5446 PCI VGA card or dummy VGA card with Bochs VESA ex-
         tensions (hardware level, including all non standard modes).

       o PS/2 mouse and keyboard

       o 2 PCI IDE interfaces with hard disk and CD-ROM support

       o Floppy disk

       o PCI and ISA network adapters

       o Serial ports

       o IPMI BMC, either and internal or external one

       o Creative SoundBlaster 16 sound card

       o ENSONIQ AudioPCI ES1370 sound card

       o Intel 82801AA AC97 Audio compatible sound card

       o Intel HD Audio Controller and HDA codec

       o Adlib (OPL2) - Yamaha YM3812 compatible chip

       o Gravis Ultrasound GF1 sound card

       o CS4231A compatible sound card

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

       SMP is supported with up to 255 CPUs.

       QEMU  uses  the  PC  BIOS from the Seabios 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" Schutz.

       Note  that,  by  default,  GUS shares IRQ(7) with parallel ports and so
       QEMU must be told to not have parallel ports to have working GUS.

          qemu_system-x86_64 dos.img -soundhw gus -parallel none

       Alternatively:

          qemu_system-x86_64 dos.img -device gus,irq=5

       Or some other unclaimed IRQ.

       CS4231A is the chip used in Windows Sound System and GUSMAX products

OPTIONS
       disk_image is a raw hard disk image for IDE hard disk 0.  Some  targets
       do not need a disk image.

   Standard options
       -h     Display help and exit

       -version
              Display version information and exit

       -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  compati-
              bility  across  releases, each release will introduce a new ver-
              sioned 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:

              accel=accels1[:accels2[:...]]
                     This  is  used to enable an accelerator. Depending on the
                     target architecture, kvm, xen, hax, hvf, whpx 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.

              vmport=on|off|auto
                     Enables  emulation  of  VMWare  IO port, for vmmouse etc.
                     auto says to select the value based  on  accel.  For  ac-
                     cel=xen the default is off otherwise the default is on.

              dump-guest-core=on|off
                     Include guest memory in a core dump. The default is on.

              mem-merge=on|off
                     Enables  or  disables memory merge support. This feature,
                     when supported by the host, de-duplicates identical  mem-
                     ory pages among VMs instances (enabled by default).

              aes-key-wrap=on|off
                     Enables  or disables AES key wrapping support on s390-ccw
                     hosts.  This feature controls whether AES  wrapping  keys
                     will  be  created to allow execution of AES cryptographic
                     functions. The default is on.

              dea-key-wrap=on|off
                     Enables or disables DEA key wrapping support on  s390-ccw
                     hosts.   This  feature controls whether DEA wrapping keys
                     will be created to allow execution of  DEA  cryptographic
                     functions. The default is on.

              nvdimm=on|off
                     Enables or disables NVDIMM support. The default is off.

              enforce-config-section=on|off
                     If  enforce-config-section  is set to on, force migration
                     code to  send  configuration  section  even  if  the  ma-
                     chine-type sets the migration.send-configuration property
                     to off. NOTE: this parameter is  deprecated.  Please  use
                     -global migration.send-configuration=on|off instead.

              memory-encryption=
                     Memory encryption object to use. The default is none.

              hmat=on|off
                     Enables  or  disables ACPI Heterogeneous Memory Attribute
                     Table (HMAT) support. The default is off.

       -cpu model
              Select CPU model (-cpu help for list and additional feature  se-
              lection)

       -accel name[,prop=value[,...]]
              This  is  used to enable an accelerator. Depending on the target
              architecture, kvm, xen, hax, hvf, whpx 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.

              igd-passthru=on|off
                     When  Xen  is  in use, this option controls whether Intel
                     integrated graphics devices can be passed through to  the
                     guest (default=off)

              kernel-irqchip=on|off|split
                     Controls  KVM  in-kernel  irqchip support. The default is
                     full acceleration of the interrupt controllers.  On  x86,
                     split  irqchip  reduces  the  kernel attack surface, at a
                     performance cost for non-MSI  interrupts.  Disabling  the
                     in-kernel  irqchip  completely  is not recommended except
                     for debugging purposes.

              kvm-shadow-mem=size
                     Defines the size of the KVM shadow MMU.

              tb-size=n
                     Controls the size (in MiB) of the TCG  translation  block
                     cache.

              thread=single|multi
                     Controls   number   of  TCG  threads.  When  the  TCG  is
                     multi-threaded there will be one thread per vCPU therefor
                     taking advantage of additional host cores. The default is
                     to enable multi-threading where  both  the  back-end  and
                     front-ends  support  it  and no incompatible TCG features
                     have been enabled (e.g.  icount/replay).

       -smp        [cpus=]n[,cores=cores][,threads=threads][,dies=dies][,sock-
       ets=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
              die, the number of threads per cores, the  number  of  dies  per
              packages and the total number of sockets can be specified. Miss-
              ing values will be computed. If  any  on  the  three  values  is
              given, the total number of CPUs n can be omitted. maxcpus speci-
              fies the maximum number of hotpluggable CPUs.

       -numa  node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initia-
       tor=initiator]

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

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

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

       -numa              hmat-lb,initiator=node,target=node,hierarchy=hierar-
       chy,data-type=tpye[,latency=lat][,bandwidth=bw]

       -numa        hmat-cache,node-id=node,size=size,level=level[,associativ-
       ity=str][,policy=str][,line=size]
              Define a NUMA node and assign RAM and VCPUs to it. Set the  NUMA
              distance  from a source node to a destination node. Set the ACPI
              Heterogeneous Memory Attributes for the given nodes.

              Legacy VCPU assignment uses 'cpus'  option  where  firstcpu  and
              lastcpu are CPU indexes. Each 'cpus' option represent a contigu-
              ous range of CPU indexes (or a single VCPU if lastcpu  is  omit-
              ted).  A  non-contiguous set of VCPUs can be represented by pro-
              viding 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.

              'initiator'  is an additional option that points to an initiator
              NUMA node that has  best  performance  (the  lowest  latency  or
              largest  bandwidth) to this NUMA node. Note that this option can
              be set only when the machine property 'hmat' is set to 'on'.

              Following example creates a machine with 2 NUMA  nodes,  node  0
              has  CPU.  node  1 has only memory, and its initiator is node 0.
              Note that because node 0 has CPU, by default  the  initiator  of
              node 0 is itself and must be itself.

                 -machine hmat=on \
                 -m 2G,slots=2,maxmem=4G \
                 -object memory-backend-ram,size=1G,id=m0 \
                 -object memory-backend-ram,size=1G,id=m1 \
                 -numa node,nodeid=0,memdev=m0 \
                 -numa node,nodeid=1,memdev=m1,initiator=0 \
                 -smp 2,sockets=2,maxcpus=2  \
                 -numa cpu,node-id=0,socket-id=0 \
                 -numa cpu,node-id=0,socket-id=1

              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 al-
              locate RAM and VCPUs respectively.

              Use 'hmat-lb' to set System Locality Latency and  Bandwidth  In-
              formation  between  initiator and target NUMA nodes in ACPI Het-
              erogeneous Attribute Memory Table (HMAT).  Initiator  NUMA  node
              can  create  memory requests, usually it has one or more proces-
              sors.  Target NUMA node contains addressable memory.

              In 'hmat-lb' option, node are NUMA node IDs.  hierarchy  is  the
              memory  hierarchy of the target NUMA node: if hierarchy is 'mem-
              ory', the structure represents the memory performance; if  hier-
              archy  is 'first-level|second-level|third-level', this structure
              represents aggregated performance of memory side caches for each
              domain.  type of 'data-type' is type of data represented by this
              structure instance: if 'hierarchy' is 'memory',  'data-type'  is
              'access|read|write'  latency or 'access|read|write' bandwidth of
              the  target  memory;   if   'hierarchy'   is   'first-level|sec-
              ond-level|third-level',  'data-type'  is 'access|read|write' hit
              latency or 'access|read|write' hit bandwidth of the target  mem-
              ory side cache.

              lat  is latency value in nanoseconds. bw is bandwidth value, the
              possible value and units are NUM[M|G|T], mean that the bandwidth
              value  are  NUM byte per second (or MB/s, GB/s or TB/s depending
              on used suffix). Note that if latency or bandwidth value  is  0,
              means  the corresponding latency or bandwidth information is not
              provided.

              In 'hmat-cache' option, node-id is the NUMA-id of the memory be-
              longs.  size is the size of memory side cache in bytes. level is
              the cache level described in this structure, note that the cache
              level  0  should not be used with 'hmat-cache' option.  associa-
              tivity  is  the  cache  associativity,  the  possible  value  is
              'none/direct(direct-mapped)/complex(complex   cache  indexing)'.
              policy is the write policy. line  is  the  cache  Line  size  in
              bytes.

              For example, the following options describe 2 NUMA nodes. Node 0
              has 2 cpus and a ram, node 1 has only a ram. The  processors  in
              node  0  access  memory in node 0 with access-latency 5 nanosec-
              onds, access-bandwidth is 200 MB/s; The processors in NUMA  node
              0  access  memory in NUMA node 1 with access-latency 10 nanosec-
              onds, access-bandwidth is 100 MB/s. And for  memory  side  cache
              information,  NUMA  node 0 and 1 both have 1 level memory cache,
              size is 10KB, policy is write-back, the cache  Line  size  is  8
              bytes:

                 -machine hmat=on \
                 -m 2G \
                 -object memory-backend-ram,size=1G,id=m0 \
                 -object memory-backend-ram,size=1G,id=m1 \
                 -smp 2 \
                 -numa node,nodeid=0,memdev=m0 \
                 -numa node,nodeid=1,memdev=m1,initiator=0 \
                 -numa cpu,node-id=0,socket-id=0 \
                 -numa cpu,node-id=0,socket-id=1 \
                 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
                 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
                 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
                 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
                 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
                 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8

       -add-fd fd=fd,set=set[,opaque=opaque]
              Add a file descriptor to an fd set. Valid options are:

              fd=fd  This option defines the file descriptor of which a dupli-
                     cate is added to fd set. The file  descriptor  cannot  be
                     stdin, stdout, or stderr.

              set=set
                     This  option defines the ID of the fd set to add the file
                     descriptor to.

              opaque=opaque
                     This option defines a free-form string that can  be  used
                     to describe fd.

              You  can open an image using pre-opened file descriptors from an
              fd set:

                 qemu-system-x86_64  -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-x86_64 -global ide-hd.physical_block_size=4096 disk-image.img

              In particular, you can use this to set driver properties for de-
              vices  which  are created automatically by the machine model. To
              create a device which is not created automatically and set prop-
              erties 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                                                              [or-
       der=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,re-
       boot-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_time-
              out ms when boot failed, then reboot.  If  rb_timeout  is  '-1',
              guest will not reboot, qemu passes '-1' to bios by default. Cur-
              rently 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-x86_64 -boot order=nc
                 # boot from CD-ROM first, switch back to default order after reboot
                 qemu_system-x86_64 -boot once=d
                 # boot with a splash picture for 5 seconds.
                 qemu_system-x86_64 -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 ver-
              sions.

       -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 key-
              codes (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 -audiodev equivalent of  the  currently  specified
              (deprecated) environment variables.

       -audiodev [driver=]driver,id=id[,prop[=value][,...]]
              Adds  a  new  audio  backend  driver identified by id. There are
              global and driver specific properties. Some values  can  be  set
              differently  for  input and output, they're marked with in|out..
              You can set the input's property with in.prop and  the  output's
              property with out.prop. For example:

                 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
                 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified

              NOTE:  parameter  validation  is known to be incomplete, in many
              cases specifying an invalid option causes QEMU to print an error
              message and continue emulation without sound.

              Valid global options are:

              id=identifier
                     Identifies the audio backend.

              timer-period=period
                     Sets  the timer period used by the audio subsystem in mi-
                     croseconds. Default is 10000 (10 ms).

              in|out.mixing-engine=on|off
                     Use QEMU's mixing engine to mix all streams  inside  QEMU
                     and convert audio formats when not supported by the back-
                     end. When off, fixed-settings must be off too. Note  that
                     disabling  this  option  means  that the selected backend
                     must support multiple streams and the audio formats  used
                     by the virtual cards, otherwise you'll get no sound. It's
                     not recommended to disable this option unless you want to
                     use 5.1 or 7.1 audio, as mixing engine only supports mono
                     and stereo audio. Default is on.

              in|out.fixed-settings=on|off
                     Use fixed settings for host  audio.  When  off,  it  will
                     change  based  on  how the guest opens the sound card. In
                     this case you must not  specify  frequency,  channels  or
                     format. Default is on.

              in|out.frequency=frequency
                     Specify  the  frequency to use when using fixed-settings.
                     Default is 44100Hz.

              in|out.channels=channels
                     Specify  the  number  of  channels  to  use  when   using
                     fixed-settings.  Default is 2 (stereo).

              in|out.format=format
                     Specify  the  sample  format to use when using fixed-set-
                     tings.  Valid values are: s8, s16,  s32,  u8,  u16,  u32,
                     f32. Default is s16.

              in|out.voices=voices
                     Specify the number of voices to use. Default is 1.

              in|out.buffer-length=usecs
                     Sets the size of the buffer in microseconds.

       -audiodev none,id=id[,prop[=value][,...]]
              Creates  a dummy backend that discards all outputs. This backend
              has no backend specific properties.

       -audiodev alsa,id=id[,prop[=value][,...]]
              Creates backend using the ALSA. This backend is  only  available
              on Linux.

              ALSA specific options are:

              in|out.dev=device
                     Specify  the  ALSA device to use for input and/or output.
                     Default is default.

              in|out.period-length=usecs
                     Sets the period length in microseconds.

              in|out.try-poll=on|off
                     Attempt to use poll mode with the device. Default is on.

              threshold=threshold
                     Threshold (in microseconds) when playback starts. Default
                     is 0.

       -audiodev coreaudio,id=id[,prop[=value][,...]]
              Creates a backend using Apple's Core Audio. This backend is only
              available on Mac OS and only supports playback.

              Core Audio specific options are:

              in|out.buffer-count=count
                     Sets the count of the buffers.

       -audiodev dsound,id=id[,prop[=value][,...]]
              Creates a backend using Microsoft's DirectSound. This backend is
              only available on Windows and only supports playback.

              DirectSound specific options are:

              latency=usecs
                     Add extra usecs microseconds latency to playback. Default
                     is 10000 (10 ms).

       -audiodev oss,id=id[,prop[=value][,...]]
              Creates a backend using OSS. This backend is available  on  most
              Unix-like systems.

              OSS specific options are:

              in|out.dev=device
                     Specify  the  file name of the OSS device to use. Default
                     is /dev/dsp.

              in|out.buffer-count=count
                     Sets the count of the buffers.

              in|out.try-poll=on|of
                     Attempt to use poll mode with the device. Default is on.

              try-mmap=on|off
                     Try using memory mapped device access. Default is off.

              exclusive=on|off
                     Open the device in exclusive mode  (vmix  won't  work  in
                     this case). Default is off.

              dsp-policy=policy
                     Sets  the  timing policy (between 0 and 10, where smaller
                     number means smaller latency but higher CPU  usage).  Use
                     -1  to  use  buffer  sizes  specified  by buffer and buf-
                     fer-count. This option is ignored if you do not have  OSS
                     4. Default is 5.

       -audiodev pa,id=id[,prop[=value][,...]]
              Creates a backend using PulseAudio. This backend is available on
              most systems.

              PulseAudio specific options are:

              server=server
                     Sets the PulseAudio server to connect to.

              in|out.name=sink
                     Use the specified source/sink for recording/playback.

              in|out.latency=usecs
                     Desired latency in microseconds.  The  PulseAudio  server
                     will  try to honor this value but actual latencies may be
                     lower or higher.

       -audiodev sdl,id=id[,prop[=value][,...]]
              Creates a backend using SDL. This backend is available  on  most
              systems,  but  you  should use your platform's native backend if
              possible. This backend has no backend specific properties.

       -audiodev spice,id=id[,prop[=value][,...]]
              Creates a backend that sends audio through SPICE.  This  backend
              requires -spice and automatically selected in that case, so usu-
              ally you can ignore this option. This  backend  has  no  backend
              specific properties.

       -audiodev wav,id=id[,prop[=value][,...]]
              Creates a backend that writes audio to a WAV file.

              Backend specific options are:

              path=path
                     Write  recorded audio into the specified file. Default is
                     qemu.wav.

       -soundhw card1[,card2,...] or -soundhw all
              Enable audio and selected sound hardware. Use  'help'  to  print
              all available sound hardware. For example:

                 qemu_system-x86_64 -soundhw sb16,adlib disk.img
                 qemu_system-x86_64 -soundhw es1370 disk.img
                 qemu_system-x86_64 -soundhw ac97 disk.img
                 qemu_system-x86_64 -soundhw hda disk.img
                 qemu_system-x86_64 -soundhw all disk.img
                 qemu_system-x86_64 -soundhw help

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

                 modprobe i810_audio clocking=48000

       -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][,furarea-
       size=val][,furdatafile=file][,guid=uuid]
              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 sys-
              tem. 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  manage-
              ment  controllers. If you don't know what this means, it is safe
              to ignore it.

              id=id  The BMC id for interfaces to use this device.

              slave_addr=val
                     Define slave address to use for the BMC. The  default  is
                     0x20.

              sdrfile=file
                     file  containing  raw Sensor Data Records (SDR) data. The
                     default is none.

              fruareasize=val
                     size of a Field Replaceable Unit (FRU) area. The  default
                     is 1024.

              frudatafile=file
                     file  containing  raw Field Replaceable Unit (FRU) inven-
                     tory data.  The default is none.

              guid=uuid
                     value for the GUID for the BMC, in standard UUID  format.
                     If  this  is  set, get "Get GUID" command to the BMC will
                     return it.  Otherwise "Get GUID" will return an error.

       -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 net-
              work.

              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 corre-
              sponding ACPI and SMBIOS entries, if appropriate.

              bmc=id The  BMC  to  connect  to,   one   of   ipmi-bmc-sim   or
                     ipmi-bmc-extern above.

              ioport=val
                     Define  the  I/O address of the interface. The default is
                     0xca0 for KCS.

              irq=val
                     Define the interrupt to use. The default is 5. To disable
                     interrupts, set this to 0.

       -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.

   Block device options
       -fda file

       -fdb file
              Use file as floppy disk 0/1 image (see disk_005fimages).

       -hda file

       -hdb file

       -hdc file

       -hdd file
              Use file as hard disk 0, 1, 2 or 3 image (see disk_005fimages).

       -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  op-
              tions 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 al-
              ready  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.

              Valid options for any block driver node:

                     driver Specifies  the  block  driver to use for the given
                            node.

                     node-name
                            This defines the name of the block driver node  by
                            which  it  will be referenced later. The name must
                            be unique, i.e. it must not match the  name  of  a
                            different block driver node, or (if you use -drive
                            as well) the ID of a drive.

                            If no node name is specified, it is  automatically
                            generated.   The  generated  node  name is not in-
                            tended to be predictable and changes between  QEMU
                            invocations.  For  the top level, an explicit node
                            name must be specified.

                     read-only
                            Open the node read-only. Guest write attempts will
                            fail.

                            Note   that   some   block  drivers  support  only
                            read-only access, either generally or  in  certain
                            configurations.  In  this  case, the default value
                            read-only=off does not work and the option must be
                            specified explicitly.

                     auto-read-only
                            If auto-read-only=on is set, QEMU may fall back to
                            read-only usage even  when  read-only=off  is  re-
                            quested,  or  even switch between modes as needed,
                            e.g.  depending  on  whether  the  image  file  is
                            writable  or whether a writing user is attached to
                            the node.

                     force-share
                            Override the image locking system of QEMU by forc-
                            ing  the  node to utilize weaker shared access for
                            permissions where it would normally request exclu-
                            sive  access. When there is the potential for mul-
                            tiple  instances  to  have  the  same  file   open
                            (whether  this  invocation of QEMU is the first or
                            the second instance), both instances  must  permit
                            shared  access  for the second instance to succeed
                            at opening the file.

                            Enabling force-share=on requires read-only=on.

                     cache.direct
                            The host page cache can be avoided with  cache.di-
                            rect=on.  This will attempt to do disk IO directly
                            to the guest's memory. QEMU may still  perform  an
                            internal copy of the data.

                     cache.no-flush
                            In  case  you don't care about data integrity over
                            host failures, you can use cache.no-flush=on. This
                            option tells QEMU that it never needs to write any
                            data to the disk but can instead  keep  things  in
                            cache. If anything goes wrong, like your host los-
                            ing power, the disk storage  getting  disconnected
                            accidentally,  etc.  your image will most probably
                            be rendered unusable.

                     discard=discard
                            discard is one of "ignore" (or "off")  or  "unmap"
                            (or "on") and controls whether discard (also known
                            as trim or unmap) requests are ignored  or  passed
                            to  the  filesystem.   Some  machine types may not
                            support discard requests.

                     detect-zeroes=detect-zeroes
                            detect-zeroes is "off", "on" or  "unmap"  and  en-
                            ables  the  automatic  conversion  of  plain  zero
                            writes by the OS to driver specific optimized zero
                            write  commands.  You  may  even choose "unmap" if
                            discard is set to "unmap" to allow a zero write to
                            be converted to an unmap operation.

              Driver-specific options for file
                     This  is  the  protocol-level  block driver for accessing
                     regular files.

                     filename
                            The path to the image file in the local filesystem

                     aio    Specifies the  AIO  backend  (threads/native,  de-
                            fault: threads)

                     locking
                            Specifies whether the image file is protected with
                            Linux OFD / POSIX locks. The default is to use the
                            Linux  Open File Descriptor API if available, oth-
                            erwise no lock is applied.  (auto/on/off, default:
                            auto)

                     Example:

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

              Driver-specific options for raw
                     This  is the image format block driver for raw images. It
                     is usually stacked on  top  of  a  protocol  level  block
                     driver such as file.

                     file   Reference  to  or  definition  of  the data source
                            block driver node (e.g. a file driver node)

                     Example 1:

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

                     Example 2:

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

              Driver-specific options for qcow2
                     This is the image format block driver for  qcow2  images.
                     It  is  usually  stacked on top of a protocol level block
                     driver such as file.

                     file   Reference to or  definition  of  the  data  source
                            block driver node (e.g. a file driver node)

                     backing
                            Reference  to  or  definition  of the backing file
                            block device (default  is  taken  from  the  image
                            file). It is allowed to pass null here in order to
                            disable the default backing file.

                     lazy-refcounts
                            Whether  to  enable  the  lazy  refcounts  feature
                            (on/off; default is taken from the image file)

                     cache-size
                            The  maximum  total  size of the L2 table and ref-
                            count block caches in bytes (default: the  sum  of
                            l2-cache-size and refcount-cache-size)

                     l2-cache-size
                            The  maximum  size  of the L2 table cache in bytes
                            (default: if cache-size is not specified - 32M  on
                            Linux  platforms,  and  8M on non-Linux platforms;
                            otherwise,  as  large  as  possible   within   the
                            cache-size,  while permitting the requested or the
                            minimal refcount cache size)

                     refcount-cache-size
                            The maximum size of the refcount  block  cache  in
                            bytes  (default:  4  times the cluster size; or if
                            cache-size is specified, the part of it  which  is
                            not used for the L2 cache)

                     cache-clean-interval
                            Clean  unused  entries  in  the  L2  and  refcount
                            caches. The interval is in  seconds.  The  default
                            value  is  600  on  supporting platforms, and 0 on
                            other platforms. Setting it  to  0  disables  this
                            feature.

                     pass-discard-request
                            Whether  discard  requests  to  the  qcow2  device
                            should be forwarded to the  data  source  (on/off;
                            default:  on  if  discard=unmap  is specified, off
                            otherwise)

                     pass-discard-snapshot
                            Whether  discard  requests  for  the  data  source
                            should  be  issued when a snapshot operation (e.g.
                            deleting a snapshot) frees clusters in  the  qcow2
                            file (on/off; default: on)

                     pass-discard-other
                            Whether  discard  requests  for  the  data  source
                            should be issued on other occasions where a  clus-
                            ter gets freed (on/off; default: off)

                     overlap-check
                            Which  overlap checks to perform for writes to the
                            image (none/constant/cached/all; default: cached).
                            For  details or finer granularity control refer to
                            the QAPI documentation of blockdev-add.

                     Example 1:

                        -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

                     Example 2:

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

              Driver-specific options for other drivers
                     Please refer to the  QAPI  documentation  of  the  block-
                     dev-add QMP command.

       -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  short-
              cut  for  defining  the  corresponding -blockdev and -device op-
              tions.

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

              file=file
                     This  option  defines  which disk image (see disk_005fim-
                     ages) to use with this drive. If  the  filename  contains
                     comma,  you must double it (for instance, "file=my,,file"
                     to use file "my,file").

                     Special files such as iSCSI devices can be specified  us-
                     ing  protocol  specific URLs. See the section for "Device
                     URL Syntax" for more information.

              if=interface
                     This option defines on which type on interface the  drive
                     is  connected.  Available  types are: ide, scsi, sd, mtd,
                     floppy, pflash, virtio, none.

              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.

              snapshot=snapshot
                     snapshot  is "on" or "off" and controls snapshot mode for
                     the given drive (see -snapshot).

              cache=cache
                     cache is "none", "writeback", "unsafe",  "directsync"  or
                     "writethrough" and controls how the host cache is used to
                     access block data. This  is  a  shortcut  that  sets  the
                     cache.direct  and  cache.no-flush  options (as in -block-
                     dev), and additionally cache.writeback, which provides  a
                     default for the write-cache option of block guest devices
                     (as in -device). The modes correspond  to  the  following
                     settings:

                  +-------------+-----------------+--------------+----------------+
                  |             | cache.writeback | cache.direct | cache.no-flush |
                  +-------------+-----------------+--------------+----------------+
                  |writeback    | on              | off          | off            |
                  +-------------+-----------------+--------------+----------------+
                  |none         | on              | on           | off            |
                  +-------------+-----------------+--------------+----------------+
                  |writethrough | off             | off          | off            |
                  +-------------+-----------------+--------------+----------------+
                  |directsync   | off             | on           | off            |
                  +-------------+-----------------+--------------+----------------+
                  |unsafe       | on              | off          | on             |
                  +-------------+-----------------+--------------+----------------+

                     The default mode is cache=writeback.

              aio=aio
                     aio is "threads", or "native" and selects between pthread
                     based disk I/O and native Linux AIO.

              format=format
                     Specify which disk format will be used  rather  than  de-
                     tecting  the format. Can be used to specify format=raw to
                     avoid interpreting an untrusted format header.

              werror=action,rerror=action
                     Specify which action to take on write  and  read  errors.
                     Valid  actions are: "ignore" (ignore the error and try to
                     continue), "stop" (pause QEMU), "report" (report the  er-
                     ror  to the guest), "enospc" (pause QEMU only if the host
                     disk is full; report the error to the  guest  otherwise).
                     The default setting is werror=enospc and rerror=report.

              copy-on-read=copy-on-read
                     copy-on-read is "on" or "off" and enables whether to copy
                     read backing file sectors into the image file.

              bps=b,bps_rd=r,bps_wr=w
                     Specify bandwidth throttling limits in bytes per  second,
                     either for all request types or for reads or writes only.
                     Small values can lead to timeouts  or  hangs  inside  the
                     guest. A safe minimum for disks is 2 MB/s.

              bps_max=bm,bps_rd_max=rm,bps_wr_max=wm
                     Specify  bursts  in  bytes per second, either for all re-
                     quest types or for reads or writes only. Bursts allow the
                     guest I/O to spike above the limit temporarily.

              iops=i,iops_rd=r,iops_wr=w
                     Specify  request  rate limits in requests per second, ei-
                     ther for all request types or for reads or writes only.

              iops_max=bm,iops_rd_max=rm,iops_wr_max=wm
                     Specify bursts in requests per second, either for all re-
                     quest types or for reads or writes only. Bursts allow the
                     guest I/O to spike above the limit temporarily.

              iops_size=is
                     Let every is bytes of a request count as  a  new  request
                     for  iops throttling purposes. Use this option to prevent
                     guests from circumventing iops limits  by  sending  fewer
                     but larger requests.

              group=g
                     Join  a  throttling  quota  group  with given name g. All
                     drives that are members of the same group  are  accounted
                     for together. Use this option to prevent guests from cir-
                     cumventing throttling limits by using  many  small  disks
                     instead of a single larger disk.

              By  default, the cache.writeback=on mode is used. It will report
              data writes as completed as soon as the data is present  in  the
              host  page  cache.  This  is safe as long as your guest OS makes
              sure to correctly flush disk caches where needed. If your  guest
              OS does not handle volatile disk write caches correctly and your
              host crashes or loses power, then the guest may experience  data
              corruption.

              For  such guests, you should consider using cache.writeback=off.
              This means that the host page cache will be  used  to  read  and
              write  data,  but  write  notification will be sent to the guest
              only after QEMU has made sure to flush each write to  the  disk.
              Be aware that this has a major impact on performance.

              When using the -snapshot option, unsafe caching is always used.

              Copy-on-read  avoids accessing the same backing file sectors re-
              peatedly and is useful when the backing file is over a slow net-
              work. By default copy-on-read is off.

              Instead of -cdrom you can use:

                 qemu-system-x86_64 -drive file=file,index=2,media=cdrom

              Instead of -hda, -hdb, -hdc, -hdd, you can use:

                 qemu-system-x86_64 -drive file=file,index=0,media=disk
                 qemu-system-x86_64 -drive file=file,index=1,media=disk
                 qemu-system-x86_64 -drive file=file,index=2,media=disk
                 qemu-system-x86_64 -drive file=file,index=3,media=disk

              You  can open an image using pre-opened file descriptors from an
              fd set:

                 qemu-system-x86_64  -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

              You can connect a CDROM to the slave of ide0:

                 qemu_system-x86_64 -drive file=file,if=ide,index=1,media=cdrom

              If you don't specify the "file=" argument, you define  an  empty
              drive:

                 qemu_system-x86_64 -drive if=ide,index=1,media=cdrom

              Instead of -fda, -fdb, you can use:

                 qemu_system-x86_64 -drive file=file,index=0,if=floppy
                 qemu_system-x86_64 -drive file=file,index=1,if=floppy

              By default, interface is "ide" and index is automatically incre-
              mented:

                 qemu_system-x86_64 -drive file=a -drive file=b"

              is interpreted like:

                 qemu_system-x86_64 -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 (see disk_005fim-
              ages).

       -fsdev   local,id=id,path=path,security_model=security_model   [,write-
       out=writeout][,readonly][,fmode=fmode][,dmode=dmode]   [,throttling.op-
       tion=value[,throttling.option=value[,...]]]

       -fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly]

       -fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly]

       -fsdev synth,id=id[,readonly]
              Define a new file system device. Valid options are:

              local  Accesses to the filesystem are done by QEMU.

              proxy  Accesses     to    the    filesystem    are    done    by
                     virtfs-proxy-helper(1).

              synth  Synthetic filesystem, only used by QTests.

              id=id  Specifies identifier for this device.

              path=path
                     Specifies the export path for  the  file  system  device.
                     Files  under this path will be available to the 9p client
                     on the guest.

              security_model=security_model
                     Specifies the security model to be used for  this  export
                     path.    Supported  security  models  are  "passthrough",
                     "mapped-xattr",    "mapped-file"    and    "none".     In
                     "passthrough"  security model, files are stored using the
                     same credentials as they are created on the  guest.  This
                     requires  QEMU to run as root. In "mapped-xattr" security
                     model, some of the file attributes like  uid,  gid,  mode
                     bits  and  link target are stored as file attributes. For
                     "mapped-file" these attributes are stored in  the  hidden
                     .virtfs_metadata  directory. Directories exported by this
                     security model cannot interact  with  other  unix  tools.
                     "none"  security  model is same as passthrough except the
                     sever won't report failures if it fails to set  file  at-
                     tributes like ownership. Security model is mandatory only
                     for local fsdriver.  Other fsdrivers (like  proxy)  don't
                     take security model as a parameter.

              writeout=writeout
                     This is an optional argument. The only supported value is
                     "immediate". This means that host page cache will be used
                     to  read  and  write  data but write notification will be
                     sent to the guest only when the data has been reported as
                     written by the storage subsystem.

              readonly
                     Enables  exporting  9p  share  as  a  readonly  mount for
                     guests. By default read-write access is given.

              socket=socket
                     Enables proxy filesystem driver to use passed socket file
                     for communicating with virtfs-proxy-helper(1).

              sock_fd=sock_fd
                     Enables  proxy filesystem driver to use passed socket de-
                     scriptor for communicating  with  virtfs-proxy-helper(1).
                     Usually  a helper like libvirt will create socketpair and
                     pass one of the fds as sock_fd.

              fmode=fmode
                     Specifies the default mode for newly created files on the
                     host.  Works only with security models "mapped-xattr" and
                     "mapped-file".

              dmode=dmode
                     Specifies the default mode for newly created  directories
                     on   the   host.   Works   only   with   security  models
                     "mapped-xattr" and "mapped-file".

              throttling.bps-total=b,throttling.bps-read=r,throt-
              tling.bps-write=w
                     Specify  bandwidth throttling limits in bytes per second,
                     either for all request types or for reads or writes only.

              throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm
                     Specify bursts in bytes per second, either  for  all  re-
                     quest types or for reads or writes only. Bursts allow the
                     guest I/O to spike above the limit temporarily.

              throttling.iops-total=i,throttling.iops-read=r,           throt-
              tling.iops-write=w
                     Specify  request  rate limits in requests per second, ei-
                     ther for all request types or for reads or writes only.

              throttling.iops-total-max=im,throttling.iops-read-max=irm,
              throttling.iops-write-max=iwm
                     Specify bursts in requests per second, either for all re-
                     quest types or for reads or writes only. Bursts allow the
                     guest I/O to spike above the limit temporarily.

              throttling.iops-size=is
                     Let  every  is  bytes of a request count as a new request
                     for iops throttling purposes.

              -fsdev option is used along with -device driver "virtio-9p-...".

       -device virtio-9p-type,fsdev=id,mount_tag=mount_tag
              Options for virtio-9p-... driver are:

              type   Specifies the variant to be used.  Supported  values  are
                     "pci", "ccw" or "device", depending on the machine type.

              fsdev=id
                     Specifies  the  id  value specified along with -fsdev op-
                     tion.

              mount_tag=mount_tag
                     Specifies the tag name to be used by the guest  to  mount
                     this export point.

       -virtfs    local,path=path,mount_tag=mount_tag    ,security_model=secu-
       rity_model[,writeout=writeout][,readonly]
       [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]

       -virtfs    proxy,socket=socket,mount_tag=mount_tag    [,writeout=write-
       out][,readonly]

       -virtfs   proxy,sock_fd=sock_fd,mount_tag=mount_tag   [,writeout=write-
       out][,readonly]

       -virtfs synth,mount_tag=mount_tag
              Define  a new filesystem device and expose it to the guest using
              a virtio-9p-device. The general form of a  Virtual  File  system
              pass-through options are:

              local  Accesses to the filesystem are done by QEMU.

              proxy  Accesses     to    the    filesystem    are    done    by
                     virtfs-proxy-helper(1).

              synth  Synthetic filesystem, only used by QTests.

              id=id  Specifies identifier for the filesystem device

              path=path
                     Specifies the export path for  the  file  system  device.
                     Files  under this path will be available to the 9p client
                     on the guest.

              security_model=security_model
                     Specifies the security model to be used for  this  export
                     path.    Supported  security  models  are  "passthrough",
                     "mapped-xattr",    "mapped-file"    and    "none".     In
                     "passthrough"  security model, files are stored using the
                     same credentials as they are created on the  guest.  This
                     requires  QEMU to run as root. In "mapped-xattr" security
                     model, some of the file attributes like  uid,  gid,  mode
                     bits  and  link target are stored as file attributes. For
                     "mapped-file" these attributes are stored in  the  hidden
                     .virtfs_metadata  directory. Directories exported by this
                     security model cannot interact  with  other  unix  tools.
                     "none"  security  model is same as passthrough except the
                     sever won't report failures if it fails to set  file  at-
                     tributes like ownership. Security model is mandatory only
                     for local fsdriver.  Other fsdrivers (like  proxy)  don't
                     take security model as a parameter.

              writeout=writeout
                     This is an optional argument. The only supported value is
                     "immediate". This means that host page cache will be used
                     to  read  and  write  data but write notification will be
                     sent to the guest only when the data has been reported as
                     written by the storage subsystem.

              readonly
                     Enables  exporting  9p  share  as  a  readonly  mount for
                     guests. By default read-write access is given.

              socket=socket
                     Enables proxy filesystem driver to use passed socket file
                     for  communicating with virtfs-proxy-helper(1). Usually a
                     helper like libvirt will create socketpair and  pass  one
                     of the fds as sock_fd.

              sock_fd
                     Enables  proxy  filesystem driver to use passed 'sock_fd'
                     as   the   socket   descriptor   for   interfacing   with
                     virtfs-proxy-helper(1).

              fmode=fmode
                     Specifies the default mode for newly created files on the
                     host.  Works only with security models "mapped-xattr" and
                     "mapped-file".

              dmode=dmode
                     Specifies  the default mode for newly created directories
                     on  the   host.   Works   only   with   security   models
                     "mapped-xattr" and "mapped-file".

              mount_tag=mount_tag
                     Specifies  the  tag name to be used by the guest to mount
                     this export point.

              multidevs=multidevs
                     Specifies how to deal with multiple devices being  shared
                     with   a  9p  export.  Supported  behaviours  are  either
                     "remap", "forbid" or "warn". The latter  is  the  default
                     behaviour  on  which virtfs 9p expects only one device to
                     be shared with the same export, and if more than one  de-
                     vice  is  shared and accessed via the same 9p export then
                     only a warning message is logged (once) by qemu  on  host
                     side.  In  order to avoid file ID collisions on guest you
                     should either create a separate virtfs  export  for  each
                     device  to be shared with guests (recommended way) or you
                     might use "remap" instead which allows you to share  mul-
                     tiple  devices  with  only  one  export instead, which is
                     achieved by remapping the  original  inode  numbers  from
                     host  to  guest  in  a way that would prevent such colli-
                     sions. Remapping inodes in such use cases is required be-
                     cause  the original device IDs from host are never passed
                     and exposed on guest. Instead  all  files  of  an  export
                     shared  with  virtfs  always  share the same device id on
                     guest. So two files with identical inode numbers but from
                     actually  different devices on host would otherwise cause
                     a file ID collision and hence potential misbehaviours  on
                     guest.  "forbid"  on  the  other hand assumes like "warn"
                     that only one device is shared by the same  export,  how-
                     ever it will not only log a warning message but also deny
                     access to additional devices on guest. Note  though  that
                     "forbid"  does  currently not block all possible file ac-
                     cess operations (e.g. readdir() would  still  return  en-
                     tries from other devices).

       -iscsi Configure iSCSI session parameters.

   USB options
       -usb   Enable  USB emulation on machine types with an on-board USB host
              controller (if not enabled by default). Note that  on-board  USB
              host  controllers  may not support USB 3.0. In this case -device
              qemu-xhci can be used instead on machines with PCI.

       -usbdevice devname
              Add the USB device devname. Note that this option is deprecated,
              please use -device usb-... instead. See usb_005fdevices.

              mouse  Virtual  Mouse.  This will override the PS/2 mouse emula-
                     tion 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.

              braille
                     Braille  device.  This  will  use  BrlAPI  to display the
                     braille output on a real or fake device.

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

              sdl    Display video output  via  SDL  (usually  in  a  separate
                     graphics window; see the SDL documentation for other pos-
                     sibilities).

              curses Display video output via curses. For graphics device mod-
                     els which support a text mode, QEMU can display this out-
                     put using a curses/ncurses  interface.  Nothing  is  dis-
                     played  when  the graphics device is in graphical mode or
                     if the graphics device does not support a text mode. Gen-
                     erally  only the VGA device models support text mode. The
                     font charset used by the guest can be specified with  the
                     charset  option,  for example charset=CP850 for IBM CP850
                     encoding. The default is CP437.

              none   Do not display video output. The guest will still see  an
                     emulated  graphics  card, but its output will not be dis-
                     played to the QEMU user. This  option  differs  from  the
                     -nographic  option  in  that it only affects what is done
                     with video output; -nographic also changes  the  destina-
                     tion of the serial and parallel port data.

              gtk    Display video output in a GTK window. This interface pro-
                     vides drop-down menus and other UI elements to  configure
                     and control the VM during runtime.

              vnc    Start a VNC server on display <arg>

              egl-headless
                     Offload  all OpenGL operations to a local DRI device. For
                     any graphical display, this display needs  to  be  paired
                     with either VNC or SPICE displays.

              spice-app
                     Start QEMU as a Spice server and launch the default Spice
                     client application. The Spice server  will  redirect  the
                     serial consoles and QEMU monitors. (Since 4.0)

       -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 dis-
              able graphical output so that QEMU is a simple command line  ap-
              plication.   The  emulated serial port is redirected on the con-
              sole and muxed with the monitor (unless redirected elsewhere ex-
              plicitly).  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.

       -alt-grab
              Use  Ctrl-Alt-Shift  to  grab  mouse (instead of Ctrl-Alt). Note
              that this also affects the special keys (for  fullscreen,  moni-
              tor-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

              port=<nr>
                     Set  the  TCP  port  spice  is listening on for plaintext
                     channels.

              addr=<addr>
                     Set the IP address spice is listening on. Default is  any
                     address.

              ipv4; ipv6; unix
                     Force using the specified IP version.

              password=<secret>
                     Set the password you need to authenticate.

              sasl   Require that the client use SASL to authenticate with the
                     spice.  The exact choice of authentication method used is
                     controlled  from  the  system / user's SASL configuration
                     file for the 'qemu' service. This is typically  found  in
                     /etc/sasl2/qemu.conf.  If running QEMU as an unprivileged
                     user, an environment variable SASL_CONF_PATH can be  used
                     to  make  it  search  alternate locations for the service
                     config. While some SASL auth  methods  can  also  provide
                     data  encryption (eg GSSAPI), it is recommended that SASL
                     always be combined with the 'tls' and 'x509' settings  to
                     enable use of SSL and server certificates. This ensures a
                     data encryption preventing compromise  of  authentication
                     credentials.

              disable-ticketing
                     Allow client connects without authentication.

              disable-copy-paste
                     Disable copy paste between the client and the guest.

              disable-agent-file-xfer
                     Disable  spice-vdagent based file-xfer between the client
                     and the guest.

              tls-port=<nr>
                     Set the TCP port spice  is  listening  on  for  encrypted
                     channels.

              x509-dir=<dir>
                     Set  the  x509  file directory. Expects same filenames as
                     -vnc $display,x509=$dir

              x509-key-file=<file>;                  x509-key-password=<file>;
              x509-cert-file=<file>;                  x509-cacert-file=<file>;
              x509-dh-key-file=<file>
                     The x509 file names can also be configured individually.

              tls-ciphers=<list>
                     Specify which ciphers to use.

              tls-channel=[main|display|cursor|inputs|record|playback]; plain-
              text-channel=[main|display|cursor|inputs|record|playback]
                     Force specific channel to be used with or without TLS en-
                     cryption. The options can be specified multiple times  to
                     configure  multiple  channels. The special name "default"
                     can be used to set the default mode. For  channels  which
                     are  not explicitly forced into one mode the spice client
                     is allowed to pick tls/plaintext as he pleases.

              image-compression=[auto_glz|auto_lz|quic|glz|lz|off]
                     Configure  image  compression  (lossless).   Default   is
                     auto_glz.

              jpeg-wan-compression=[auto|never|always];  zlib-glz-wan-compres-
              sion=[auto|never|always]
                     Configure wan image compression (lossy for  slow  links).
                     Default is auto.

              streaming-video=[off|all|filter]
                     Configure video stream detection. Default is off.

              agent-mouse=[on|off]
                     Enable/disable  passing mouse events via vdagent. Default
                     is on.

              playback-compression=[on|off]
                     Enable/disable  audio  stream  compression  (using   celt
                     0.5.1).  Default is on.

              seamless-migration=[on|off]
                     Enable/disable spice seamless migration. Default is off.

              gl=[on|off]
                     Enable/disable OpenGL context. Default is off.

              rendernode=<file>
                     DRM  render  node for OpenGL rendering. If not specified,
                     it will pick the first available. (Since 2.9)

       -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

              cirrus Cirrus Logic GD5446  Video  card.  All  Windows  versions
                     starting  from  Windows  95 should recognize and use this
                     graphic card. For optimal performances, use 16 bit  color
                     depth  in  the  guest and the host OS. (This card was the
                     default before QEMU 2.2)

              std    Standard VGA card with  Bochs  VBE  extensions.  If  your
                     guest  OS supports the VESA 2.0 VBE extensions (e.g. Win-
                     dows XP) and if you want to use high resolution modes (>=
                     1280x1024x16) then you should use this option. (This card
                     is the default since QEMU 2.2)

              vmware VMWare SVGA-II compatible adapter. Use  it  if  you  have
                     sufficiently  recent XFree86/XOrg server or Windows guest
                     with a driver for this card.

              qxl    QXL paravirtual graphic card. It is VGA  compatible  (in-
                     cluding  VESA 2.0 VBE support). Works best with qxl guest
                     drivers installed though. Recommended choice  when  using
                     the spice protocol.

              tcx    (sun4m  only)  Sun  TCX  framebuffer. This is the default
                     framebuffer for sun4m machines and offers both 8-bit  and
                     24-bit colour depths at a fixed resolution of 1024x768.

              cg3    (sun4m  only)  Sun  cgthree framebuffer. This is a simple
                     8-bit framebuffer for sun4m machines  available  in  both
                     1024x768  (OpenBIOS) and 1152x900 (OBP) resolutions aimed
                     at people wishing to run older Solaris versions.

              virtio Virtio VGA card.

              none   Disable VGA card.

       -full-screen
              Start in full screen.

       -g widthxheight[xdepth]
              Set the initial  graphical  resolution  and  depth  (PPC,  SPARC
              only).

              For PPC the default is 800x600x32.

              For   SPARC  with  the  TCX  graphics  device,  the  default  is
              1024x768x8 with the option of 1024x768x24. For cgthree, the  de-
              fault is 1024x768x8 with the option of 1152x900x8 for people who
              wish to use OBP.

       -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  de-
              vice  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

              to=L   With this option, QEMU will try next available  VNC  dis-
                     plays,  until  the  number  L,  if the origianlly defined
                     "-vnc display" is not available, e.g.  port  5900+display
                     is already used by another application. By default, to=0.

              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 con-
                     nections 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" connec-
                     tion.   The  client  is specified by the display. For re-
                     verse network connections (host:d,``reverse``), the d ar-
                     gument is a TCP port number, not a display number.

              websocket
                     Opens  an  additional TCP listening port dedicated to VNC
                     Websocket connections. If  a  bare  websocket  option  is
                     given, the Websocket port is 5700+display. An alternative
                     port can be specified with the syntax websocket=port.

                     If host is specified connections  will  only  be  allowed
                     from  this  host. It is possible to control the websocket
                     listen  address  independently,  using  the  syntax  web-
                     socket=host:port.

                     If no TLS credentials are provided, the websocket connec-
                     tion runs in unencrypted mode.  If  TLS  credentials  are
                     provided,  the  websocket  connection  requires encrypted
                     client connections.

              password
                     Require that password based authentication  is  used  for
                     client connections.

                     The  password  must be set separately using the set_pass-
                     word command in  the  pcsys_005fmonitor.  The  syntax  to
                     change  your  password is: set_password <protocol> <pass-
                     word> where <protocol> could be either "vnc" or "spice".

                     If you would like to change <protocol>  password  expira-
                     tion,  you should use expire_password <protocol> <expira-
                     tion-time> where expiration time could be one of the fol-
                     lowing  options: now, never, +seconds or UNIX time of ex-
                     piration, e.g. +60 to make password expire in 60 seconds,
                     or  1335196800  to  make  password  expire on "Mon Apr 23
                     12:00:00 EDT 2012" (UNIX time for this date and time).

                     You can also use keywords "now" or "never" for the  expi-
                     ration  time to allow <protocol> password to expire imme-
                     diately or never expire.

              tls-creds=ID
                     Provides the ID of a set of TLS credentials to use to se-
                     cure  the  VNC server. They will apply to both the normal
                     VNC server socket and the websocket socket (if  enabled).
                     Setting  TLS credentials will cause the VNC server socket
                     to enable the VeNCrypt auth  mechanism.  The  credentials
                     should  have  been  previously  created using the -object
                     tls-creds argument.

              tls-authz=ID
                     Provides  the  ID  of  the  QAuthZ  authorization  object
                     against  which  the client's x509 distinguished name will
                     validated. This object is only resolved at time  of  use,
                     so  can be deleted and recreated on the fly while the VNC
                     server is active. If missing, it will default to  denying
                     access.

              sasl   Require that the client use SASL to authenticate with the
                     VNC server. The exact  choice  of  authentication  method
                     used is controlled from the system / user's SASL configu-
                     ration file for the 'qemu'  service.  This  is  typically
                     found  in /etc/sasl2/qemu.conf. If running QEMU as an un-
                     privileged user, an environment  variable  SASL_CONF_PATH
                     can be used to make it search alternate locations for the
                     service config. While some SASL  auth  methods  can  also
                     provide  data  encryption  (eg GSSAPI), it is recommended
                     that SASL always be combined with the  'tls'  and  'x509'
                     settings  to  enable  use of SSL and server certificates.
                     This ensures a data encryption preventing  compromise  of
                     authentication credentials. See the vnc_005fsecurity sec-
                     tion for details on using SASL authentication.

              sasl-authz=ID
                     Provides  the  ID  of  the  QAuthZ  authorization  object
                     against  which the client's SASL username will validated.
                     This object is only resolved at time of use,  so  can  be
                     deleted  and recreated on the fly while the VNC server is
                     active. If missing, it will default to denying access.

              acl    Legacy  method  for  enabling  authorization  of  clients
                     against the x509 distinguished name and SASL username. It
                     results in the creation of two  authz-list  objects  with
                     IDs  of  vnc.username  and  vnc.x509dname.  The rules for
                     these objects must be configured with the  HMP  ACL  com-
                     mands.

                     This  option  is deprecated and should no longer be used.
                     The new sasl-authz and tls-authz options are  a  replace-
                     ment.

              lossy  Enable  lossy  compression methods (gradient, JPEG, ...).
                     If this option is  set,  VNC  client  may  receive  lossy
                     framebuffer  updates  depending on its encoding settings.
                     Enabling this option can save a lot of bandwidth  at  the
                     expense of quality.

              non-adaptive
                     Disable  adaptive  encodings.  Adaptive encodings are en-
                     abled by default. An adaptive encoding will try to detect
                     frequently  updated  screen  regions, and send updates in
                     these regions using a lossy encoding  (like  JPEG).  This
                     can  be  really  helpful  to  save bandwidth when playing
                     videos. Disabling adaptive encodings restores the  origi-
                     nal static behavior of encodings like Tight.

              share=[allow-exclusive|force-shared|ignore]
                     Set  display  sharing  policy.  'allow-exclusive'  allows
                     clients to ask for exclusive access. As suggested by  the
                     rfb  spec  this  is implemented by dropping other connec-
                     tions. Connecting multiple clients in  parallel  requires
                     all  clients  asking  for  a  shared  session (vncviewer:
                     -shared switch). This  is  the  default.   'force-shared'
                     disables exclusive client access. Useful for shared desk-
                     top sessions, where you  don't  want  someone  forgetting
                     specify  -shared disconnect everybody else. 'ignore' com-
                     pletely ignores the shared flag and allows everybody con-
                     nect unconditionally. Doesn't conform to the rfb spec but
                     is traditional QEMU behavior.

              key-delay-ms
                     Set keyboard delay, for key down and key  up  events,  in
                     milliseconds.  Default is 10. Keyboards are low-bandwidth
                     devices, so this slowdown can help the device  and  guest
                     to  keep up and not lose events in case events are arriv-
                     ing in bulk.  Possible causes for the  latter  are  flaky
                     network connections, or scripts for automated testing.

              audiodev=audiodev
                     Use  the  specified audiodev when the VNC client requests
                     audio transmission. When not using an -audiodev argument,
                     this option must be omitted, otherwise is must be present
                     and specify a valid audiodev.

   i386 target only
       -win2k-hack
              Use it when installing Windows 2000 to avoid a  disk  full  bug.
              After  Windows 2000 is installed, you no longer need this option
              (this option slows down the IDE transfers).

       -no-fd-bootchk
              Disable boot signature checking for floppy disks in BIOS. May be
              needed to boot from old floppy disks.

       -no-acpi
              Disable  ACPI  (Advanced Configuration and Power Interface) sup-
              port.  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_ta-
       ble_id=str][,oem_rev=n]                [,asl_compiler_id=str][,asl_com-
       piler_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 spec-
              ified  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  re-
              quired 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][,re-
       lease=%d.%d][,uefi=on|off]
              Specify SMBIOS type 0 fields

       -smbios      type=1[,manufacturer=str][,product=str][,version=str][,se-
       rial=str][,uuid=uuid][,sku=str][,family=str]
              Specify SMBIOS type 1 fields

       -smbios      type=2[,manufacturer=str][,product=str][,version=str][,se-
       rial=str][,asset=str][,location=str]
              Specify SMBIOS type 2 fields

       -smbios       type=3[,manufacturer=str][,version=str][,serial=str][,as-
       set=str][,sku=str]
              Specify SMBIOS type 3 fields

       -smbios     type=4[,sock_pfx=str][,manufacturer=str][,version=str][,se-
       rial=str][,asset=str][,part=str]
              Specify SMBIOS type 4 fields

       -smbios        type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,se-
       rial=str][,asset=str][,part=str][,speed=%d]
              Specify SMBIOS type 17 fields

   Network options
       -nic
       [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]
              This option is a shortcut for configuring both the on-board (de-
              fault) guest NIC hardware and the host network  backend  in  one
              go.   The  host  backend options are the same as with the corre-
              sponding -netdev options below. The guest NIC model can  be  set
              with  model=modelname.  Use model=help to list the available de-
              vice  types.  The  hardware  MAC  address  can   be   set   with
              mac=macaddr.

              The  following two example do exactly the same, to show how -nic
              can be used to shorten the command line length:

                 qemu-system-x86_64 -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
                 qemu-system-x86_64 -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32

       -nic none
              Indicate that no network devices should  be  configured.  It  is
              used  to  override  the  default configuration (default NIC with
              "user" host network backend) which is activated if no other net-
              working options are provided.

       -netdev user,id=id[,option][,option][,...]
              Configure  user  mode host network backend which requires no ad-
              ministrator privilege to run. Valid options are:

              id=id  Assign symbolic name for use in monitor commands.

              ipv4=on|off and ipv6=on|off
                     Specify that either IPv4 or IPv6 must be enabled. If nei-
                     ther is specified both protocols are enabled.

              net=addr[/mask]
                     Set  IP  network  address  the guest will see. Optionally
                     specify the netmask, either in the  form  a.b.c.d  or  as
                     number of valid top-most bits. Default is 10.0.2.0/24.

              host=addr
                     Specify the guest-visible address of the host. Default is
                     the 2nd IP in the guest network, i.e. x.x.x.2.

              ipv6-net=addr[/int]
                     Set IPv6 network address the guest will see  (default  is
                     fec0::/64).  The  network  prefix  is  given in the usual
                     hexadecimal IPv6 address notation. The prefix size is op-
                     tional, and is given as the number of valid top-most bits
                     (default is 64).

              ipv6-host=addr
                     Specify the guest-visible IPv6 address of the  host.  De-
                     fault is the 2nd IPv6 in the guest network, i.e. xxxx::2.

              restrict=on|off
                     If  this  option  is enabled, the guest will be isolated,
                     i.e. it will not be able to contact the host and no guest
                     IP  packets  will be routed over the host to the outside.
                     This option does not affect any explicitly set forwarding
                     rules.

              hostname=name
                     Specifies  the  client  hostname reported by the built-in
                     DHCP server.

              dhcpstart=addr
                     Specify the first of the 16 IPs the built-in DHCP  server
                     can  assign.  Default is the 15th to 31st IP in the guest
                     network, i.e. x.x.x.15 to x.x.x.31.

              dns=addr
                     Specify the guest-visible address of  the  virtual  name-
                     server.  The  address must be different from the host ad-
                     dress. Default is the 3rd IP in the guest  network,  i.e.
                     x.x.x.3.

              ipv6-dns=addr
                     Specify  the  guest-visible  address  of the IPv6 virtual
                     nameserver. The address must be different from  the  host
                     address.   Default  is  the  3rd IP in the guest network,
                     i.e. xxxx::3.

              dnssearch=domain
                     Provides an entry for the domain-search list sent by  the
                     built-in  DHCP server. More than one domain suffix can be
                     transmitted by specifying this option multiple times.  If
                     supported, this will cause the guest to automatically try
                     to append the given domain suffix(es) in  case  a  domain
                     name can not be resolved.

                     Example:

                        qemu-system-x86_64 -nic user,dnssearch=mgmt.example.org,dnssearch=example.org

              domainname=domain
                     Specifies the client domain name reported by the built-in
                     DHCP server.

              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).

              tftp-server-name=name
                     In BOOTP reply, broadcast name as the "TFTP server  name"
                     (RFC2132 option 66). This can be used to advise the guest
                     to load boot files or  configurations  from  a  different
                     server than the host address.

              bootfile=file
                     When using the user mode network stack, broadcast file as
                     the BOOTP filename. In conjunction with tftp, this can be
                     used to network boot a guest from a local directory.

                     Example (using pxelinux):

                        qemu-system-x86_64 -hda linux.img -boot n -device e1000,netdev=n1     -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0

              smb=dir[,smbserver=addr]
                     When  using  the  user  mode  network  stack,  activate a
                     built-in SMB server so that Windows OSes  can  access  to
                     the  host  files  in dir transparently. The IP address of
                     the SMB server can be set to addr. By default the 4th  IP
                     in the guest network is used, i.e. x.x.x.4.

                     In the guest Windows OS, the line:

                        10.0.2.4 smbserver

                     must be added in the file C:\WINDOWS\LMHOSTS (for windows
                     9x/Me) or C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS  (Windows
                     NT/2000).

                     Then dir can be accessed in \\smbserver\qemu.

                     Note  that  a  SAMBA server must be installed on the host
                     OS.

              hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport
                     Redirect incoming TCP or UDP connections to the host port
                     hostport  to the guest IP address guestaddr on guest port
                     guestport. If guestaddr is not specified,  its  value  is
                     x.x.x.15  (default  first  address  given by the built-in
                     DHCP server). By specifying hostaddr,  the  rule  can  be
                     bound to a specific host interface. If no connection type
                     is set, TCP is used. This option can  be  given  multiple
                     times.

                     For  example, to redirect host X11 connection from screen
                     1 to guest screen 0, use the following:

                        # on the host
                        qemu-system-x86_64 -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
                        # this host xterm should open in the guest X11 server
                        xterm -display :1

                     To redirect telnet connections from  host  port  5555  to
                     telnet port on the guest, use the following:

                        # on the host
                        qemu-system-x86_64 -nic user,hostfwd=tcp::5555-:23
                        telnet localhost 5555

                     Then  when you use on the host telnet localhost 5555, you
                     connect to the guest telnet server.

              guestfwd=[tcp]:server:port-dev;                           guest-
              fwd=[tcp]:server:port-cmd:command
                     Forward guest TCP connections to the IP address server on
                     port port to the character device dev or to a program ex-
                     ecuted by cmd:command which gets spawned for each connec-
                     tion. This option can be given multiple times.

                     You can either use a chardev directly and have  that  one
                     used  throughout  QEMU's  lifetime, like in the following
                     example:

                        # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
                        # the guest accesses it
                        qemu-system-x86_64 -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321

                     Or you can execute a command on every TCP connection  es-
                     tablished  by  the guest, so that QEMU behaves similar to
                     an inetd process for that virtual server:

                        # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
                        # and connect the TCP stream to its stdin/stdout
                        qemu-system-x86_64 -nic  'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'

       -netdev             tap,id=id[,fd=h][,ifname=name][,script=file][,down-
       script=dfile][,br=bridge][,helper=helper]
              Configure a host TAP network backend with ID id.

              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-x86_64 linux.img -nic tap

                 #launch a QEMU instance with two NICs, each one connected
                 #to a TAP device
                 qemu-system-x86_64 linux.img         -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0         -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1

                 #launch a QEMU instance with the default network helper to
                 #connect a TAP device to bridge br0
                 qemu-system-x86_64 linux.img -device virtio-net-pci,netdev=n1         -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"

       -netdev bridge,id=id[,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-x86_64 linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1

                 #launch a QEMU instance with the default network helper to
                 #connect a TAP device to bridge qemubr0
                 qemu-system-x86_64 linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1

       -netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]
              This host network backend can be used  to  connect  the  guest's
              network  to another QEMU virtual machine using a TCP socket con-
              nection. If listen is specified, QEMU waits for incoming connec-
              tions  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-x86_64 linux.img                  -device e1000,netdev=n1,mac=52:54:00:12:34:56                  -netdev socket,id=n1,listen=:1234
                 # connect the network of this instance to the network of the first instance
                 qemu-system-x86_64 linux.img                  -device e1000,netdev=n2,mac=52:54:00:12:34:57                  -netdev socket,id=n2,connect=127.0.0.1:1234

       -netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]
              Configure  a  socket  host  network backend to share the guest's
              network traffic with another QEMU virtual machines using  a  UDP
              multicast  socket,  effectively making a bus for every QEMU with
              same multicast address maddr and port. NOTES:

              1. Several QEMU can be running on different hosts and share same
                 bus (assuming correct multicast setup for these hosts).

              2. mcast  support  is  compatible with User Mode Linux (argument
                 ethN=mcast), see http://user-mode-linux.sf.net.

              3. Use fd=h to specify an already opened UDP multicast socket.

              Example:

                 # launch one QEMU instance
                 qemu-system-x86_64 linux.img                  -device e1000,netdev=n1,mac=52:54:00:12:34:56                  -netdev socket,id=n1,mcast=230.0.0.1:1234
                 # launch another QEMU instance on same "bus"
                 qemu-system-x86_64 linux.img                  -device e1000,netdev=n2,mac=52:54:00:12:34:57                  -netdev socket,id=n2,mcast=230.0.0.1:1234
                 # launch yet another QEMU instance on same "bus"
                 qemu-system-x86_64 linux.img                  -device e1000,netdev=n3,mac=52:54:00:12:34:58                  -netdev socket,id=n3,mcast=230.0.0.1:1234

              Example (User Mode Linux compat.):

                 # launch QEMU instance (note mcast address selected is UML's default)
                 qemu-system-x86_64 linux.img                  -device e1000,netdev=n1,mac=52:54:00:12:34:56                  -netdev socket,id=n1,mcast=239.192.168.1:1102
                 # launch UML
                 /path/to/linux ubd0=/path/to/root_fs eth0=mcast

              Example (send packets from host's 1.2.3.4):

                 qemu-system-x86_64 linux.img                  -device e1000,netdev=n1,mac=52:54:00:12:34:56                  -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4

       -netdev    l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dst-
       port=dstport],txsession=txsession[,rxsession=rxses-
       sion][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=tx-
       cookie][,rxcookie=rxcookie][,offset=offset]
              Configure  a  L2TPv3  pseudowire  host  network  backend. L2TPv3
              (RFC3931) 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  on-
              wards).

              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  speci-
                     fication.  Their function is mostly to prevent misconfig-
                     uration. 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-x86_64 linux.img -device e1000,netdev=n1     -netdev l2tpv3,id=n1,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=group-
       name][,mode=octalmode]
              Configure VDE backend to connect to PORT n of a vde switch  run-
              ning  on  host and listening for incoming connections on socket-
              path. 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  en-
              abled.

              Example:

                 # launch vde switch
                 vde_switch -F -sock /tmp/myswitch
                 # launch QEMU instance
                 qemu-system-x86_64 linux.img -nic vde,sock=/tmp/myswitch

       -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

       -netdev hubport,id=id,hubid=hubid[,netdev=nd]
              Create a hub port on the emulated hub with ID hubid.

              The hubport netdev lets you connect a NIC to a QEMU emulated hub
              instead of a single netdev. Alternatively, you can also  connect
              the  hubport to another netdev with ID nd by using the netdev=nd
              option.

       -net                         nic[,netdev=nd][,macaddr=mac][,model=type]
       [,name=name][,addr=addr][,vectors=v]
              Legacy option to configure or create an on-board (or machine de-
              fault) Network Interface Card(NIC) and connect it either to  the
              emulated  hub with ID 0 (i.e. the default hub), or to the netdev
              nd.  If model is omitted, then the default NIC model  associated
              with  the  machine type is used. Note that the default NIC model
              may change in future QEMU releases, so it is highly  recommended
              to  always  specify  a model. 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. Option-
              ally, for PCI cards, you can specify the number v of MSI-X  vec-
              tors  that  the card should have; this option currently only af-
              fects virtio cards; set v = 0 to disable MSI-X. If no  -net  op-
              tion  is  specified,  a  single NIC is created. QEMU can emulate
              several  different   models   of   network   card.    Use   -net
              nic,model=help for a list of available devices for your target.

       -net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]
              Configure a host network backend (with the options corresponding
              to the same -netdev option) and connect it to the emulated hub 0
              (the default hub). Use name to specify the name of the hub port.

   Character device options
       The general form of a character device option is:

       -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 deter-
              mine 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 moni-
              tor:

                 -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  configura-
              tion; for instance you could have a TCP port multiplexed between
              UART 0 and UART 1, and stdio multiplexed between the QEMU  moni-
              tor 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. See mux_005fkeys.

              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 con-
              sole and the monitor to stdio.

              There is currently no support for multiplexing in the other  di-
              rection  (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 trun-
              cated or appended to when opened.

       The available backends are:

       -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  op-
              tions.

       -chardev      socket,id=id[,TCP      options      or      unix      op-
       tions][,server][,nowait][,telnet][,websocket][,reconnect=sec-
       onds][,tls-creds=id][,tls-authz=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.

              websocket specifies that the socket uses WebSocket protocol  for
              communication.

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

              tls-creds requests enablement of the TLS  protocol  for  encryp-
              tion, 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.

              tls-auth  provides  the  ID  of  the QAuthZ authorization object
              against which the client's x509 distinguished name will be vali-
              dated.  This  object  is only resolved at time of use, so can be
              deleted and recreated on the fly while the chardev server is ac-
              tive.  If missing, it will default to denying access.

              TCP and unix socket options are given below:

              TCP  options: port=port[,host=host][,to=to][,ipv4][,ipv6][,node-
              lay]
                     host for a listening socket specifies the  local  address
                     to  be  bound. For a connecting socket species the remote
                     host to connect to. host is optional for listening  sock-
                     ets. If not specified it defaults to 0.0.0.0.

                     port  for  a listening socket specifies the local port to
                     be bound. For a connecting socket specifies the  port  on
                     the  remote  host to connect to. port can be given as ei-
                     ther a port number or a service name. port is required.

                     to is only relevant to listening sockets. If it is speci-
                     fied, and port cannot be bound, QEMU will attempt to bind
                     to subsequent ports up to and including to until it  suc-
                     ceeds. to must be specified as a port number.

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

                     nodelay disables the Nagle algorithm.

              unix options: path=path
                     path specifies the local path of the unix socket. path is
                     required.

       -chardev  udp,id=id[,host=host],port=port[,localaddr=localaddr][,local-
       port=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 speci-
              fied 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 re-
              quired.

       -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 in-
              cludes 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  op-
              tions.

       -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 re-
              quired.

       -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).

   TPM device options
       The general form of a TPM device option is:

       -tpmdev backend,id=id[,options]
              The specific backend type will determine the applicable options.
              The -tpmdev option creates the TPM backend and requires  a  -de-
              vice option that specifies the TPM frontend interface model.

              Use -tpmdev help to print all available TPM backend types.

       The available backends are:

       -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 de-
              fault /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.  can-
              cel-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  ini-
              tialize  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  re-
              booted  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 tp-
              mdev=tpm0 in the device option.

       -tpmdev emulator,id=id,chardev=dev
              (Linux-host only) Enable access to a TPM emulator using Unix do-
              main 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

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

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

       -append cmdline
              Use cmdline as kernel command line

       -initrd file
              Use file as initial ram disk.

       -initrd file1 arg=foo,file2
              This syntax is only available with multiboot.

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

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

   Debug/Expert options
       -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  parame-
              ter.

              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 con-
              tents 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:

              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 charac-
                     ters:

                        vc:80Cx24C

              pty    [Linux only] Pseudo TTY (a new PTY is automatically allo-
                     cated)

              none   No device is allocated.

              null   void device

              chardev:id
                     Use a named character device defined  with  the  -chardev
                     option.

              /dev/XXX
                     [Linux  only] Use host tty, e.g. /dev/ttyS0. The host se-
                     rial port parameters are set according  to  the  emulated
                     ones.

              /dev/parportN
                     [Linux  only,  parallel port only] Use host parallel port
                     N.  Currently SPP and EPP parallel port features  can  be
                     used.

              file:filename
                     Write output to filename. No character can be read.

              stdio  [Unix only] standard input/output

              pipe:filename
                     name pipe filename

              COMn   [Windows only] Use host serial port n

              udp:[remote_host]:remote_port[@[src_ip]:src_port]
                     This  implements  UDP  Net  Console.  When remote_host or
                     src_ip are not specified they default  to  0.0.0.0.  When
                     not using a specified src_port a random port is automati-
                     cally 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  some-
                     thing  to that port it will appear in the netconsole ses-
                     sion.

                     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  acti-
                     vates  telnet  remote echo and single char transfer, then
                     you can use the following options  to  set  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][,reconnect=seconds]
                     The TCP Net Console has two modes of  operation.  It  can
                     send  the  serial I/O to a location or wait for a connec-
                     tion 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. The reconnect option only applies if
                     noserver is set, if the connection goes down it will  at-
                     tempt  to  reconnect  at  the  given interval. 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  se-
                     quence. Typically in unix telnet you do it with Control-]
                     and then type "send break" followed by pressing the enter
                     key.

              websocket:host:port,server[,nowait][,nodelay]
                     The WebSocket protocol is used instead of raw tcp socket.
                     The port acts as a WebSocket server. Client mode  is  not
                     supported.

              unix:path[,server][,nowait][,reconnect=seconds]
                     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 connec-
                     tions.

              mon:dev_string
                     This is a special option to allow the monitor to be  mul-
                     tiplexed  onto  another  serial  port. The monitor is ac-
                     cessed with key sequence of Control-a and  then  pressing
                     c.  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

                     When  the  monitor  is  multiplexed to stdio in this way,
                     Ctrl+C will not terminate  QEMU  any  more  but  will  be
                     passed to the guest instead.

              braille
                     Braille  device.  This  will  use  BrlAPI  to display the
                     braille output on a real or fake device.

              msmouse
                     Three button serial mouse. Configure the guest to use Mi-
                     crosoft protocol.

       -parallel dev
              Redirect  the virtual parallel port to host device dev (same de-
              vices 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 paral-
              lel ports.

              Use -parallel none to disable all parallel ports.

       -monitor dev
              Redirect the monitor to host device dev (same devices as the se-
              rial 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][,pretty[=on|off]]
              Setup monitor on chardev  name.  pretty  turns  on  JSON  pretty
              printing easing human reading and debugging.

       -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 typ-
              ically  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.

       --preconfig
              Pause QEMU for interactive configuration before the  machine  is
              created,  which  allows querying and configuring properties that
              will affect machine initialization. Use QMP command 'x-exit-pre-
              config'  to  exit the preconfig state and move to the next state
              (i.e. run guest if -S isn't used or pause the second time if  -S
              is used). This option is experimental.

       -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).

       -overcommit mem-lock=on|off

       -overcommit cpu-pm=on|off
              Run qemu with hints about host resource overcommit. The  default
              is to assume that host overcommits all resources.

              Locking  qemu  and  guest  memory can be enabled via mem-lock=on
              (disabled by default). This works when host memory is not  over-
              committed  and reduces the worst-case latency for guest. This is
              equivalent to realtime.

              Guest ability to manage power state of host cpus (increasing la-
              tency  for  other processes on the same host cpu, but decreasing
              latency for guest) can be enabled via cpu-pm=on (disabled by de-
              fault). This works best when host CPU is not overcommitted. When
              used, host estimates of CPU cycle and power utilization will  be
              incorrect, not taking into account guest idle time.

       -gdb dev
              Accept  a gdb connection on device dev (see gdb_005fusage). Note
              that this option does not pause QEMU execution --  if  you  want
              QEMU to not start the guest until you connect with gdb and issue
              a continue command, you will need to also pass the -S option  to
              QEMU.

              The most usual configuration is to listen on a local TCP socket:

                 -gdb tcp::3117

              but  you  can  specify  other backends; UDP, pseudo TTY, or even
              stdio are all reasonable use cases. For example, a stdio connec-
              tion  allows you to start QEMU from within gdb and establish the
              connection via a pipe:

                 (gdb) target remote | exec qemu-system-x86_64 -gdb stdio ...

       -s     Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP  port
              1234 (see gdb_005fusage).

       -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  ad-
              dresses.   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.

       -seed number
              Force the guest to use a deterministic pseudo-random number gen-
              erator, seeded with number. This does not affect crypto routines
              within the host.

       -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.

       -xen-domid id
              Specify xen guest domain id (XEN only).

       -xen-attach
              Attach to existing xen domain. libxl 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 em-
              ulation. 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  initializa-
              tion race conditions.

       -option-rom file
              Load  the contents of file as an option ROM. This option is use-
              ful to load things like EtherBoot.

       -rtc           [base=utc|localtime|datetime][,clock=host|rt|vm][,drift-
       fix=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    datetime    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 al-
              lows 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, which provides a host monotonic clock if  host  support
              it.  To even prevent the RTC from progressing during suspension,
              you can set clock to vm (virtual clock).  'clock=vm'  is  recom-
              mended  especially in icount mode in order to preserve determin-
              ism; however, note that in icount mode the speed of the  virtual
              clock is variable and can in general differ from the host clock.

              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,rrsnap-
       shot=snapshot]
              Enable virtual instruction counter. The virtual cpu will execute
              one instruction every 2^N ns of virtual time. If auto is  speci-
              fied  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 dead-
              line  instantly  whenever the virtual cpu goes to sleep mode and
              will not advance if no timer is enabled. This behavior give  de-
              terministic 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  cor-
              relation 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 in-
              form 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  en-
              abled.  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  snap-
              shot  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:

              ib700  iBASE  700  is  a  very simple ISA watchdog with a single
                     timer.

              i6300esb
                     Intel 6300ESB I/O controller hub is a much more  feature-
                     ful PCI-based dual-timer watchdog.

              diag288
                     A  virtual  watchdog for s390x backed by the diagnose 288
                     hypercall (currently KVM only).

       -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),
              inject-nmi (inject a NMI  into  the  guest),  pause  (pause  the
              guest),  debug (print a debug message and continue), or none (do
              nothing).

              Note that the shutdown action requires that the  guest  responds
              to  ACPI  signals, which it may not be able to do in the sort of
              situations where the  watchdog  would  have  expired,  and  thus
              -watchdog-action shutdown is not recommended for production use.

              Examples:

              -watchdog i6300esb -watchdog-action pause; -watchdog ib700

       -echr numeric_ascii_value
              Change  the  escape  character used for switching to the monitor
              when using monitor and serial sharing. The default is 0x01  when
              using  the  -nographic  option.  0x01  is equal to pressing Con-
              trol-a. You can select a different character from the ascii con-
              trol 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

       -show-cursor
              Show cursor.

       -tb-size n
              Set  TCG  translation  block cache size. Deprecated, use '-accel
              tcg,tb-size=n' instead.

       -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 moni-
              tor can be used to change settings (such  as  migration  parame-
              ters)  prior to issuing the migrate_incoming to allow the migra-
              tion 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,  moni-
              tor 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 spec-
              ified directory. Especially useful in combination with -runas.

       -runas user
              Immediately  before  starting  guest execution, drop root privi-
              leges, switching to the specified user.

       -prom-env variable=value
              Set OpenBIOS nvram variable to given value (PPC, SPARC only).

                 qemu-system-sparc -prom-env 'auto-boot?=false' \
                  -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'

                 qemu-system-ppc -prom-env 'auto-boot?=false' \
                  -prom-env 'boot-device=hd:2,\yaboot' \
                  -prom-env 'boot-args=conf=hd:2,\yaboot.conf'

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

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

              See the -semihosting-config option documentation for further in-
              formation about the facilities this enables.

       -semihosting-config                         [enable=on|off][,target=na-
       tive|gdb|auto][,chardev=id][,arg=str[,...]]
              Enable  and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios
              II only).

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

              On  Arm  this  implements  the standard semihosting API, version
              2.0.

              On M68K this implements the "ColdFire  GDB"  interface  used  by
              libgloss.

              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.

              target=native|gdb|auto
                     Defines where the semihosting calls will be addressed, to
                     QEMU (native) or to GDB (gdb). The default is auto, which
                     means gdb during debug sessions and native otherwise.

              chardev=str1
                     Send the output to a chardev backend output for native or
                     auto output when not in gdb

              arg=str1,arg=str2,...
                     Allows the user to pass input arguments, and can be  used
                     multiple  times  to  build up a list. The old-style -ker-
                     nel/-append method of passing a  command  line  is  still
                     supported for backward compatibility. If both the --semi-
                     hosting-config arg and the -kernel/-append are specified,
                     the  former  is  passed to semihosting as it always takes
                     precedence.

       -old-param
              Old param mode (ARM only).

       -sandbox                           arg[,obsolete=string][,elevateprivi-
       leges=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'.

              obsolete=string
                     Enable Obsolete system calls

              elevateprivileges=string
                     Disable set*uid|gid system calls

              spawn=string
                     Disable *fork and execve

              resourcecontrol=string
                     Disable process affinity and schedular priority

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

       -writeconfig file
              Write device configuration to file. The file can be either file-
              name  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=]PATTERN
                     Immediately enable events matching PATTERN (either  event
                     name  or a globbing pattern).  This option is only avail-
                     able if QEMU has been compiled with the  simple,  log  or
                     ftrace  tracing  backend.   To specify multiple events or
                     patterns, specify the -trace option multiple times.

                     Use -trace help to print a list of names of trace points.

              events=FILE
                     Immediately enable events listed in FILE.  The file  must
                     contain one event name (as listed in the trace-events-all
                     file) per line; globbing patterns are accepted too.  This
                     option  is  only available if QEMU has been compiled with
                     the simple, log or ftrace tracing backend.

              file=FILE
                     Log output traces to FILE.  This option is only available
                     if  QEMU  has been compiled with the simple tracing back-
                     end.

       -plugin file=file[,arg=string]
              Load a plugin.

              file=file
                     Load the given plugin from a shared library file.

              arg=string
                     Argument string passed to the plugin. (Can be given  mul-
                     tiple times.)

       -enable-fips
              Enable FIPS 140-2 compliance mode.

       -msg timestamp[=on|off]
              Control error message format.

              timestamp=on|off
                     Prefix messages with a timestamp. Default is off.

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

       -enable-sync-profile
              Enable synchronization profiling.

   Generic object creation
       -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.

              -object                                             memory-back-
              end-file,id=id,size=size,mem-path=dir,share=on|off,dis-
              card-data=on|off,merge=on|off,dump=on|off,preal-
              loc=on|off,host-nodes=host-nodes,policy=default|pre-
              ferred|bind|interleave,align=align
                     Creates a memory file backend object, which can  be  used
                     to back the guest RAM with huge pages.

                     The id parameter is a unique ID that will be used to ref-
                     erence this memory region when configuring the -numa  ar-
                     gument.

                     The  size  option provides the size of the memory region,
                     and accepts common suffixes, eg 500M.

                     The mem-path provides the path to either a shared  memory
                     or huge page filesystem mount.

                     The  share  boolean  option determines whether the memory
                     region is marked as private to QEMU, or shared. The  lat-
                     ter  allows a co-operating external process to access the
                     QEMU memory region.

                     The share is also required for pvrdma devices due to lim-
                     itations in the RDMA API provided by Linux.

                     Setting  share=on  might  affect the ability to configure
                     NUMA bindings for the memory backend under  some  circum-
                     stances,  see  Documentation/vm/numa_memory_policy.txt on
                     the Linux kernel source tree for additional details.

                     Setting the discard-data boolean option to  on  indicates
                     that  file  contents can be destroyed when QEMU exits, to
                     avoid unnecessarily flushing data to  the  backing  file.
                     Note  that discard-data is only an optimization, and QEMU
                     might not discard file contents if it aborts unexpectedly
                     or is terminated using SIGKILL.

                     The merge boolean option enables memory merge, also known
                     as MADV_MERGEABLE, so that Kernel Samepage  Merging  will
                     consider the pages for memory deduplication.

                     Setting  the dump boolean option to off excludes the mem-
                     ory from core  dumps.  This  feature  is  also  known  as
                     MADV_DONTDUMP.

                     The prealloc boolean option enables memory preallocation.

                     The host-nodes option binds the memory range to a list of
                     NUMA host nodes.

                     The policy option sets the NUMA policy to one of the fol-
                     lowing values:

                     default
                            default host policy

                     preferred
                            prefer the given host node list for allocation

                     bind   restrict  memory allocation to the given host node
                            list

                     interleave
                            interleave memory  allocations  across  the  given
                            host node list

                     The  align  option  specifies  the base address alignment
                     when QEMU mmap(2) mem-path, and accepts common  suffixes,
                     eg  2M. Some backend store specified by mem-path requires
                     an alignment different than the default one used by QEMU,
                     eg  the  device  DAX  /dev/dax0.0  requires  2M alignment
                     rather than 4K. In such cases, users can specify the  re-
                     quired alignment via this option.

                     The pmem option specifies whether the backing file speci-
                     fied by mem-path is in host persistent memory that can be
                     accessed using the SNIA NVM programming model (e.g. Intel
                     NVDIMM). If pmem is set to 'on', QEMU will take necessary
                     operations to guarantee the persistence of its own writes
                     to mem-path (e.g. in vNVDIMM label emulation and live mi-
                     gration).   Also,  we  will  map  the  backend-file  with
                     MAP_SYNC flag, which ensures the file metadata is in sync
                     for  mem-path  in  case of host crash or a power failure.
                     MAP_SYNC requires  support  from  both  the  host  kernel
                     (since  Linux kernel 4.15) and the filesystem of mem-path
                     mounted with DAX option.

              -object                                             memory-back-
              end-ram,id=id,merge=on|off,dump=on|off,share=on|off,preal-
              loc=on|off,size=size,host-nodes=host-nodes,policy=default|pre-
              ferred|bind|interleave
                     Creates  a  memory  backend  object, which can be used to
                     back the guest RAM. Memory  backend  objects  offer  more
                     control  than the -m option that is traditionally used to
                     define guest RAM.  Please  refer  to  memory-backend-file
                     for a description of the options.

              -object                                             memory-back-
              end-memfd,id=id,merge=on|off,dump=on|off,share=on|off,preal-
              loc=on|off,size=size,host-nodes=host-nodes,policy=default|pre-
              ferred|bind|interleave,seal=on|off,hugetlb=on|off,hugetlb-
              size=size
                     Creates  an  anonymous  memory file backend object, which
                     allows QEMU to share the memory with an external  process
                     (e.g.  when  using  vhost-user).  The memory is allocated
                     with memfd and optional sealing. (Linux only)

                     The seal option creates a sealed-file,  that  will  block
                     further resizing the memory ('on' by default).

                     The hugetlb option specify the file to be created resides
                     in the hugetlbfs filesystem (since Linux 4.14).  Used  in
                     conjunction  with the hugetlb option, the hugetlbsize op-
                     tion specify the hugetlb page size on systems  that  sup-
                     port multiple hugetlb page sizes (it must be a power of 2
                     value supported by the system).

                     In some versions of Linux, the hugetlb option  is  incom-
                     patible  with  the  seal  option (requires at least Linux
                     4.16).

                     Please refer to memory-backend-file for a description  of
                     the other options.

                     The share boolean option is on by default with memfd.

              -object rng-builtin,id=id
                     Creates  a  random number generator backend which obtains
                     entropy from QEMU builtin functions. The id parameter  is
                     a  unique  ID that will be used to reference this entropy
                     backend from the virtio-rng device. By default, the  vir-
                     tio-rng device uses this RNG backend.

              -object rng-random,id=id,filename=/dev/random
                     Creates  a  random number generator backend which obtains
                     entropy from a device on the host. The id parameter is  a
                     unique  ID  that  will  be used to reference this entropy
                     backend from the virtio-rng device. The filename  parame-
                     ter  specifies  which  file to obtain entropy from and if
                     omitted defaults to /dev/urandom.

              -object rng-egd,id=id,chardev=chardevid
                     Creates a random number generator backend  which  obtains
                     entropy  from an external daemon running on the host. The
                     id parameter is a unique ID that will be used  to  refer-
                     ence this entropy backend from the virtio-rng device. The
                     chardev parameter is the unique ID of a character  device
                     backend that provides the connection to the RNG daemon.

              -object                       tls-creds-anon,id=id,endpoint=end-
              point,dir=/path/to/cred/dir,verify-peer=on|off
                     Creates a TLS anonymous credentials object, which can  be
                     used  to  provide TLS support on network backends. The id
                     parameter is a unique ID which network backends will  use
                     to  access the credentials. The endpoint is either server
                     or client depending on whether the QEMU  network  backend
                     that  uses  the credentials will be acting as a client or
                     as a server. If verify-peer is enabled (the default) then
                     once  the  handshake  is  completed, the peer credentials
                     will be verified, though this is a  no-op  for  anonymous
                     credentials.

                     The dir parameter tells QEMU where to find the credential
                     files.  For server endpoints, this directory may  contain
                     a  file dh-params.pem providing diffie-hellman parameters
                     to use for the TLS server. If the file is  missing,  QEMU
                     will  generate a set of DH parameters at startup. This is
                     a computationally expensive operation that consumes  ran-
                     dom  pool entropy, so it is recommended that a persistent
                     set of parameters be generated upfront and saved.

              -object                        tls-creds-psk,id=id,endpoint=end-
              point,dir=/path/to/keys/dir[,username=username]
                     Creates  a  TLS Pre-Shared Keys (PSK) credentials object,
                     which can be used to provide TLS support on network back-
                     ends. The id parameter is a unique ID which network back-
                     ends will use to access the credentials. The endpoint  is
                     either  server  or  client  depending on whether the QEMU
                     network backend that uses the credentials will be  acting
                     as  a  client or as a server.  For clients only, username
                     is the username which will be  sent  to  the  server.  If
                     omitted it defaults to "qemu".

                     The dir parameter tells QEMU where to find the keys file.
                     It is called "dir/keys.psk" and  contains  "username:key"
                     pairs.  This  file  can  most easily be created using the
                     GnuTLS psktool program.

                     For  server  endpoints,  dir  may  also  contain  a  file
                     dh-params.pem  providing diffie-hellman parameters to use
                     for the TLS server.  If the file is  missing,  QEMU  will
                     generate  a  set  of  DH parameters at startup. This is a
                     computationally expensive operation that consumes  random
                     pool  entropy, so it is recommended that a persistent set
                     of parameters be generated up front and saved.

              -object                       tls-creds-x509,id=id,endpoint=end-
              point,dir=/path/to/cred/dir,priority=priority,ver-
              ify-peer=on|off,passwordid=id
                     Creates a TLS anonymous credentials object, which can  be
                     used  to  provide TLS support on network backends. The id
                     parameter is a unique ID which network backends will  use
                     to  access the credentials. The endpoint is either server
                     or client depending on whether the QEMU  network  backend
                     that  uses  the credentials will be acting as a client or
                     as a server. If verify-peer is enabled (the default) then
                     once  the  handshake  is  completed, the peer credentials
                     will be verified. With x509  certificates,  this  implies
                     that  the clients must be provided with valid client cer-
                     tificates too.

                     The dir parameter tells QEMU where to find the credential
                     files.   For server endpoints, this directory may contain
                     a file dh-params.pem providing diffie-hellman  parameters
                     to  use  for the TLS server. If the file is missing, QEMU
                     will generate a set of DH parameters at startup. This  is
                     a  computationally expensive operation that consumes ran-
                     dom pool entropy, so it is recommended that a  persistent
                     set of parameters be generated upfront and saved.

                     For  x509 certificate credentials the directory will con-
                     tain further files providing the x509  certificates.  The
                     certificates  must  be stored in PEM format, in filenames
                     ca-cert.pem, ca-crl.pem (optional), server-cert.pem (only
                     servers),  server-key.pem (only servers), client-cert.pem
                     (only clients), and client-key.pem (only clients).

                     For the server-key.pem  and  client-key.pem  files  which
                     contain  sensitive private keys, it is possible to use an
                     encrypted version by providing the passwordid  parameter.
                     This  provides  the ID of a previously created secret ob-
                     ject containing the password for decryption.

                     The priority parameter allows to override the global  de-
                     fault  priority used by gnutls. This can be useful if the
                     system administrator needs to use a weaker set of  crypto
                     priorities for QEMU without potentially forcing the weak-
                     ness onto all applications. Or conversely  if  one  wants
                     wants  a stronger default for QEMU than for all other ap-
                     plications, they can do this through this parameter.  Its
                     format  is  a  gnutls  priority  string  as  described at
                     https://gnutls.org/manual/html_node/Priority-Strings.html.

              -object               filter-buffer,id=id,netdev=netdevid,inter-
              val=t[,queue=all|rx|tx][,status=on|off][,posi-
              tion=head|tail|id=<id>][,insert=behind|before]
                     Interval t can't be 0, this filter batches the packet de-
                     livery: all packets arriving in a given interval on  net-
                     dev  netdevid  are delayed until the end of the interval.
                     Interval is in microseconds. status is optional that  in-
                     dicate whether the netfilter is on (enabled) or off (dis-
                     abled), the default status for netfilter will be 'on'.

                     queue all|rx|tx is an option that can be applied  to  any
                     netfilter.

                     all:  the  filter is attached both to the receive and the
                     transmit queue of the netdev (default).

                     rx: the filter is attached to the receive  queue  of  the
                     netdev, where it will receive packets sent to the netdev.

                     tx:  the  filter is attached to the transmit queue of the
                     netdev, where it will receive packets sent by the netdev.

                     position head|tail|id=<id> is an option to specify  where
                     the  filter should be inserted in the filter list. It can
                     be applied to any netfilter.

                     head: the filter is inserted at the head  of  the  filter
                     list, before any existing filters.

                     tail:  the  filter  is inserted at the tail of the filter
                     list, behind any existing filters (default).

                     id=<id>: the filter is inserted before or behind the fil-
                     ter specified by <id>, see the insert option below.

                     insert behind|before is an option to specify where to in-
                     sert the new filter relative to the  one  specified  with
                     position=id=<id>. It can be applied to any netfilter.

                     before: insert before the specified filter.

                     behind: insert behind the specified filter (default).

              -object       filter-mirror,id=id,netdev=netdevid,outdev=charde-
              vid,queue=all|rx|tx[,vnet_hdr_support][,posi-
              tion=head|tail|id=<id>][,insert=behind|before]
                     filter-mirror  on  netdev  netdevid,mirror  net packet to
                     chardevchardevid, if it has  the  vnet_hdr_support  flag,
                     filter-mirror will mirror packet with vnet_hdr_len.

              -object    filter-redirector,id=id,netdev=netdevid,indev=charde-
              vid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,posi-
              tion=head|tail|id=<id>][,insert=behind|before]
                     filter-redirector  on  netdev  netdevid,redirect filter's
                     net packet  to  chardev  chardevid,and  redirect  indev's
                     packet  to  filter.if  it  has the vnet_hdr_support flag,
                     filter-redirector will redirect packet with vnet_hdr_len.
                     Create  a  filter-redirector  we need to differ outdev id
                     from indev id, id can not be the same. we  can  just  use
                     indev or outdev, but at least one of indev or outdev need
                     to be specified.

              -object                      filter-rewriter,id=id,netdev=netde-
              vid,queue=all|rx|tx,[vnet_hdr_support][,posi-
              tion=head|tail|id=<id>][,insert=behind|before]
                     Filter-rewriter is a part of COLO project.It will rewrite
                     tcp  packet  to  secondary from primary to keep secondary
                     tcp connection,and rewrite tcp  packet  to  primary  from
                     secondary  make tcp packet can be handled by client.if it
                     has the vnet_hdr_support flag, we can parse  packet  with
                     vnet header.

                     usage:    colo    secondary:    -object   filter-redirec-
                     tor,id=f1,netdev=hn0,queue=tx,indev=red0   -object   fil-
                     ter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -ob-
                     ject filter-rewriter,id=rew0,netdev=hn0,queue=all

              -object                 filter-dump,id=id,netdev=dev[,file=file-
              name][,maxlen=len][,position=head|tail|id=<id>][,insert=be-
              hind|before]
                     Dump the network traffic on netdev dev to the file speci-
                     fied  by filename. 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.

              -object             colo-compare,id=id,primary_in=chardevid,sec-
              ondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_sup-
              port][,notify_dev=id][,compare_timeout=@var{ms}][,ex-
              pired_scan_cycle=@var{ms}
                     Colo-compare gets  packet  from  primary_inchardevid  and
                     secondary_inchardevid,  than  compare primary packet with
                     secondary packet. If the packets are same, we will output
                     primary  packet  to  outdevchardevid, else we will notify
                     colo-frame do checkpoint and send primary packet to  out-
                     devchardevid.  In order to improve efficiency, we need to
                     put the task of comparison in another thread. If  it  has
                     the  vnet_hdr_support  flag,  colo compare will send/recv
                     packet with vnet_hdr_len.  Then  compare_timeout=@var{ms}
                     determines  the  maximum  delay colo-compare wait for the
                     packet.  The expired_scan_cycle=@var{ms} to set  the  pe-
                     riod  of  scanning  expired primary node network packets.
                     If you want to use Xen COLO, will need the notify_dev  to
                     notify Xen colo-frame to do checkpoint.

                     we  must  use  it with the help of filter-mirror and fil-
                     ter-redirector.

                        KVM COLO

                        primary:
                        -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
                        -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
                        -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
                        -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
                        -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
                        -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
                        -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
                        -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
                        -object iothread,id=iothread1
                        -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
                        -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
                        -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
                        -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1

                        secondary:
                        -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
                        -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
                        -chardev socket,id=red0,host=3.3.3.3,port=9003
                        -chardev socket,id=red1,host=3.3.3.3,port=9004
                        -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
                        -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1

                        Xen COLO

                        primary:
                        -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
                        -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
                        -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
                        -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
                        -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
                        -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
                        -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
                        -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
                        -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait
                        -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
                        -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
                        -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
                        -object iothread,id=iothread1
                        -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1

                        secondary:
                        -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
                        -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
                        -chardev socket,id=red0,host=3.3.3.3,port=9003
                        -chardev socket,id=red1,host=3.3.3.3,port=9004
                        -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
                        -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1

                     If you want to know the detail of above command line, you
                     can read the colo-compare git log.

              -object cryptodev-backend-builtin,id=id[,queues=queues]
                     Creates   a   cryptodev  backend  which  executes  crypto
                     opreation from the QEMU cipher APIS. The id parameter  is
                     a unique ID that will be used to reference this cryptodev
                     backend from the virtio-crypto device. The queues parame-
                     ter  is optional, which specify the queue number of cryp-
                     todev backend, the default of queues is 1.

                        # qemu-system-x86_64   [...]       -object cryptodev-backend-builtin,id=cryptodev0       -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0   [...]

              -object               cryptodev-vhost-user,id=id,chardev=charde-
              vid[,queues=queues]
                     Creates  a  vhost-user  cryptodev  backend,  backed  by a
                     chardev chardevid. The id parameter is a unique  ID  that
                     will be used to reference this cryptodev backend from the
                     virtio-crypto device. 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. The
                     queues parameter is optional,  which  specify  the  queue
                     number  of  cryptodev  backend for multiqueue vhost-user,
                     the default of queues is 1.

                        # qemu-system-x86_64   [...]       -chardev socket,id=chardev0,path=/path/to/socket       -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0       -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0   [...]

              -object    secret,id=id,data=string,format=raw|base64[,keyid=se-
              cretid,iv=string]

              -object  secret,id=id,file=filename,format=raw|base64[,keyid=se-
              cretid,iv=string]
                     Defines a secret to store a password, encryption key,  or
                     some  other sensitive data. The sensitive data can either
                     be passed directly via the data parameter, or  indirectly
                     via the file parameter. Using the data parameter is inse-
                     cure unless the sensitive data is encrypted.

                     The sensitive data can be provided in raw format (the de-
                     fault),  or  base64. When encoded as JSON, the raw format
                     only supports valid UTF-8 characters, so base64 is recom-
                     mended  for  sending  binary data. QEMU will convert from
                     which ever format is provided to the format it needs  in-
                     ternally. eg, an RBD password can be provided in raw for-
                     mat, even though it will be base64  encoded  when  passed
                     onto the RBD sever.

                     For  added protection, it is possible to encrypt the data
                     associated with a secret using  the  AES-256-CBC  cipher.
                     Use of encryption is indicated by providing the keyid and
                     iv parameters. The keyid parameter provides the ID  of  a
                     previously  defined  secret that contains the AES-256 de-
                     cryption key. This key should be  32-bytes  long  and  be
                     base64 encoded. The iv parameter provides the random ini-
                     tialization vector used for encryption of this particular
                     secret  and  should  be  a base64 encrypted string of the
                     16-byte IV.

                     The simplest (insecure) usage is to  provide  the  secret
                     inline

                        # qemu-system-x86_64 -object secret,id=sec0,data=letmein,format=raw

                     The  simplest secure usage is to provide the secret via a
                     file

                     # printf "letmein"  >  mypasswd.txt  #  QEMU_SYSTEM_MACRO
                     -object secret,id=sec0,file=mypasswd.txt,format=raw

                     For  greater security, AES-256-CBC should be used. To il-
                     lustrate usage, consider the openssl  command  line  tool
                     which  can  encrypt  the data. Note that when encrypting,
                     the plaintext must be padded to the cipher block size (32
                     bytes) using the standard PKCS#5/6 compatible padding al-
                     gorithm.

                     First a master key needs to be created in  base64  encod-
                     ing:

                        # openssl rand -base64 32 > key.b64
                        # KEY=$(base64 -d key.b64 | hexdump  -v -e '/1 "%02X"')

                     Each  secret  to be encrypted needs to have a random ini-
                     tialization vector generated. These do  not  need  to  be
                     kept secret

                        # openssl rand -base64 16 > iv.b64
                        # IV=$(base64 -d iv.b64 | hexdump  -v -e '/1 "%02X"')

                     The  secret  to  be defined can now be encrypted, in this
                     case we're telling openssl to base64 encode  the  result,
                     but it could be left as raw bytes if desired.

                        # SECRET=$(printf "letmein" |
                                   openssl enc -aes-256-cbc -a -K $KEY -iv $IV)

                     When  launching  QEMU, create a master secret pointing to
                     key.b64 and specify that to be used to decrypt  the  user
                     password.  Pass  the contents of iv.b64 to the second se-
                     cret

                        # qemu-system-x86_64     -object secret,id=secmaster0,format=base64,file=key.b64     -object secret,id=sec0,keyid=secmaster0,format=base64,        data=$SECRET,iv=$(<iv.b64)

              -object                      sev-guest,id=id,cbitpos=cbitpos,re-
              duced-phys-bits=val,[sev-device=string,policy=policy,handle=han-
              dle,dh-cert-file=file,session-file=file]
                     Create a Secure Encrypted Virtualization (SEV) guest  ob-
                     ject,  which  can be used to provide the guest memory en-
                     cryption support on AMD processors.

                     When memory encryption is enabled, one  of  the  physical
                     address bit (aka the C-bit) is utilized to mark if a mem-
                     ory page is protected. The cbitpos is used to provide the
                     C-bit  position. The C-bit position is Host family depen-
                     dent hence user must provide this  value.  On  EPYC,  the
                     value should be 47.

                     When  memory encryption is enabled, we loose certain bits
                     in physical address space. The reduced-phys-bits is  used
                     to  provide  the  number of bits we loose in physical ad-
                     dress space.  Similar to C-bit, the value is Host  family
                     dependent. On EPYC, the value should be 5.

                     The sev-device provides the device file to use for commu-
                     nicating with the SEV firmware running inside AMD  Secure
                     Processor.  The default device is '/dev/sev'. If hardware
                     supports memory encryption then /dev/sev devices are cre-
                     ated by CCP driver.

                     The  policy  provides  the guest policy to be enforced by
                     the SEV firmware and restrict what configuration and  op-
                     erational  commands can be performed on this guest by the
                     hypervisor. The policy should be provided  by  the  guest
                     owner  and  is  bound  to the guest and cannot be changed
                     throughout the lifetime of the guest. The default is 0.

                     If guest policy allows sharing the key with  another  SEV
                     guest  then  handle  can  be use to provide handle of the
                     guest from which to share the key.

                     The dh-cert-file  and  session-file  provides  the  guest
                     owner's  Public  Diffie-Hillman  key defined in SEV spec.
                     The PDH and session parameters are used for  establishing
                     a cryptographic session with the guest owner to negotiate
                     keys used for attestation. The file must  be  encoded  in
                     base64.

                     e.g to launch a SEV guest

                        # qemu_system-x86_64     ......
                            -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5     -machine ...,memory-encryption=sev0
                            .....

              -object authz-simple,id=id,identity=string
                     Create  an  authorization object that will control access
                     to network services.

                     The identity parameter is identifies  the  user  and  its
                     format  depends on the network service that authorization
                     object is associated with. For authorizing based  on  TLS
                     x509  certificates, the identity must be the x509 distin-
                     guished name. Note that care must be taken to escape  any
                     commas in the distinguished name.

                     An  example  authorization object to validate a x509 dis-
                     tinguished name would look like:

                        # qemu-system-x86_64     ...
                            -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB'     ...

                     Note the use of quotes due to the x509 distinguished name
                     containing whitespace, and escaping of ','.

              -object authz-listfile,id=id,filename=path,refresh=yes|no
                     Create  an  authorization object that will control access
                     to network services.

                     The filename parameter is the fully qualified path  to  a
                     file  containing  the  access  control list rules in JSON
                     format.

                     An example set of rules that match against SASL usernames
                     might look like:

                        {
                          "rules": [
                             { "match": "fred", "policy": "allow", "format": "exact" },
                             { "match": "bob", "policy": "allow", "format": "exact" },
                             { "match": "danb", "policy": "deny", "format": "glob" },
                             { "match": "dan*", "policy": "allow", "format": "exact" },
                          ],
                          "policy": "deny"
                        }

                     When checking access the object will iterate over all the
                     rules and the first rule to match will  have  its  policy
                     value returned as the result. If no rules match, then the
                     default policy value is returned.

                     The rules can either be an exact string  match,  or  they
                     can  use  the  simple UNIX glob pattern matching to allow
                     wildcards to be used.

                     If refresh is set to true the file will be monitored  and
                     automatically reloaded whenever its content changes.

                     As  with the authz-simple object, the format of the iden-
                     tity strings being matched depends on  the  network  ser-
                     vice,  but is usually a TLS x509 distinguished name, or a
                     SASL username.

                     An example authorization object to validate a SASL  user-
                     name would look like:

                        # qemu-system-x86_64     ...
                            -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=yes
                            ...

              -object authz-pam,id=id,service=string
                     Create  an  authorization object that will control access
                     to network services.

                     The service parameter provides the name of a PAM  service
                     to  use  for  authorization.  It  requires  that  a  file
                     /etc/pam.d/service exist to provide the configuration for
                     the account subsystem.

                     An  example  authorization  object to validate a TLS x509
                     distinguished name would look like:

                        # qemu-system-x86_64     ...
                            -object authz-pam,id=auth0,service=qemu-vnc
                            ...

                     There would then be a corresponding config file  for  PAM
                     at /etc/pam.d/qemu-vnc that contains:

                        account requisite  pam_listfile.so item=user sense=allow \
                                   file=/etc/qemu/vnc.allow

                     Finally  the  /etc/qemu/vnc.allow  file would contain the
                     list of x509 distingished names that are permitted access

                        CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB

              -object                                                      io-
              thread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink
                     Creates a dedicated event loop thread that devices can be
                     assigned to. This is known as an IOThread. By default de-
                     vice emulation happens in vCPU threads or the main  event
                     loop  thread.   This can become a scalability bottleneck.
                     IOThreads allow device emulation and I/O to run on  other
                     host CPUs.

                     The id parameter is a unique ID that will be used to ref-
                     erence this IOThread from -device ...,iothread=id.   Mul-
                     tiple  devices  can be assigned to an IOThread. Note that
                     not all devices support an iothread parameter.

                     The query-iothreads QMP command lists IOThreads  and  re-
                     ports  their  thread  IDs  so that the user can configure
                     host CPU pinning/affinity.

                     IOThreads use an adaptive  polling  algorithm  to  reduce
                     event loop latency. Instead of entering a blocking system
                     call to monitor file descriptors and then pay the cost of
                     being  woken  up  when an event occurs, the polling algo-
                     rithm spins waiting for events for a short time. The  al-
                     gorithm's  default parameters are suitable for many cases
                     but can be adjusted based on knowledge  of  the  workload
                     and/or host device latency.

                     The  poll-max-ns  parameter  is  the  maximum  number  of
                     nanoseconds to busy wait for events. Polling can be  dis-
                     abled by setting this value to 0.

                     The  poll-grow  parameter  is  the multiplier used to in-
                     crease the polling time when the algorithm detects it  is
                     missing events due to not polling long enough.

                     The poll-shrink parameter is the divisor used to decrease
                     the polling time when the algorithm detects it is  spend-
                     ing too long polling without encountering events.

                     The  polling parameters can be modified at run-time using
                     the qom-set command (where iothread1  is  the  IOThread's
                     id):

                        (qemu) qom-set /objects/iothread1 poll-max-ns 100000

       During the graphical emulation, you can use special key combinations to
       change modes. The default key mappings are shown below, but if you  use
       -alt-grab then the modifier is Ctrl-Alt-Shift (instead of Ctrl-Alt) and
       if you use -ctrl-grab then the modifier is the right Ctrl key  (instead
       of Ctrl-Alt):

       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:

              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  a  character  backend  multiplexer
       (which  is  the  default if you are using -nographic) then several com-
       mands are available via an escape sequence.  These  key  sequences  all
       start  with an escape character, which is Ctrl-a by default, but can be
       changed with -echr. The list below assumes you're using the default.

       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  (usu-
              ally this switches between the monitor and the console)

       Ctrl-a Ctrl-a
              Send the escape character to the frontend

NOTES
       In  addition  to  using normal file images for the emulated storage de-
       vices, QEMU can also use networked resources  such  as  iSCSI  devices.
       These are specified using a special URL syntax.

       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://<tar-
              get-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 re-
              quired for this feature.

              Example (without authentication):

                 qemu-system-x86_64 -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-x86_64 -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-x86_64 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1

       NBD    QEMU supports NBD (Network Block Devices) both using TCP  proto-
              col  as  well as Unix Domain Sockets. With TCP, the default port
              is 10809.

              Syntax for specifying a NBD device using TCP, in  preferred  URI
              form: "nbd://<server-ip>[:<port>]/[<export>]"

              Syntax  for  specifying  a NBD device using Unix Domain Sockets;
              remember that '?' is a shell glob character and may  need  quot-
              ing: "nbd+unix:///[<export>]?socket=<domain-socket>"

              Older       syntax       that      is      also      recognized:
              "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-x86_64 --drive file=nbd:192.0.2.1:30000

              Example for Unix Domain Sockets

                 qemu-system-x86_64 --drive file=nbd:unix:/tmp/nbd-socket

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

              Examples:

                 qemu-system-x86_64 -drive file=ssh://user@host/path/to/disk.img
                 qemu-system-x86_64 -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 au-
              thentication 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-x86_64 --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:

              protocol
                     'http', 'https', 'ftp', or 'ftps'.

              username
                     Optional  username  for  authentication  to  the   remote
                     server.

              password
                     Optional   password  for  authentication  to  the  remote
                     server.

              host   Address of the remote server.

              path   Path on the remote server, including any query string.

              The following options are also supported:

              url    The full URL when passing options to the  driver  explic-
                     itly.

              readahead
                     The  amount of data to read ahead with each range request
                     to the remote server. This value may optionally have  the
                     suffix  'T',  'G',  'M',  'K', 'k' or 'b'. If it does not
                     have a suffix, it will be assumed to  be  in  bytes.  The
                     value  must  be  a multiple of 512 bytes.  It defaults to
                     256k.

              sslverify
                     Whether to verify the remote  server's  certificate  when
                     connecting over SSL. It can have the value 'on' or 'off'.
                     It defaults to 'on'.

              cookie Send this cookie (it can also be a list of cookies  sepa-
                     rated  by ';') with each outgoing request. Only supported
                     when using protocols such as HTTP which support  cookies,
                     otherwise ignored.

              timeout
                     Set  the  timeout in seconds of the CURL connection. This
                     timeout is the time that CURL waits for a  response  from
                     the  remote  server  to  get  the size of the image to be
                     downloaded. If not set, the default timeout of 5  seconds
                     is used.

              Note that when passing options to qemu explicitly, driver is the
              value of <protocol>.

              Example: boot from a remote Fedora 20 live ISO image

                 qemu_system-x86_64 --drive media=cdrom,file=https://archives.fedoraproject.org/pub/archive/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://archives.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly

              Example: boot from a remote Fedora 20 cloud image using a  local
              overlay for writes, copy-on-read, and a readahead of 64k

                 qemu-img create -f qcow2 -o backing_file='json:{"file.driver":"http",, "file.url":"http://archives.fedoraproject.org/pub/archive/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

              Example:  boot  from  an image stored on a VMware vSphere server
              with a self-signed certificate using a local overlay for writes,
              a readahead of 64k and a timeout of 10 seconds.

                 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

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

AUTHOR
       Fabrice Bellard

COPYRIGHT
       2020, The QEMU Project Developers

5.0.0                            Jul 22, 2020                          QEMU(1)

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