1HXCOMM Use DEFHEADING() to define headings in both help text and rST.
   2HXCOMM Text between SRST and ERST is copied to the rST version and
   3HXCOMM discarded from C version.
   4HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to
   5HXCOMM construct option structures, enums and help message for specified
   6HXCOMM architectures.
   7HXCOMM HXCOMM can be used for comments, discarded from both rST and C.
   9DEFHEADING(Standard options:)
  11DEF("help", 0, QEMU_OPTION_h,
  12    "-h or -help     display this help and exit\n", QEMU_ARCH_ALL)
  15    Display help and exit
  18DEF("version", 0, QEMU_OPTION_version,
  19    "-version        display version information and exit\n", QEMU_ARCH_ALL)
  22    Display version information and exit
  25DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
  26    "-machine [type=]name[,prop[=value][,...]]\n"
  27    "                selects emulated machine ('-machine help' for list)\n"
  28    "                property accel=accel1[:accel2[:...]] selects accelerator\n"
  29    "                supported accelerators are kvm, xen, hax, hvf, nvmm, whpx or tcg (default: tcg)\n"
  30    "                vmport=on|off|auto controls emulation of vmport (default: auto)\n"
  31    "                dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
  32    "                mem-merge=on|off controls memory merge support (default: on)\n"
  33    "                aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
  34    "                dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
  35    "                suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
  36    "                nvdimm=on|off controls NVDIMM support (default=off)\n"
  37    "                memory-encryption=@var{} memory encryption object to use (default=none)\n"
  38    "                hmat=on|off controls ACPI HMAT support (default=off)\n"
  39    "                memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n",
  40    QEMU_ARCH_ALL)
  42``-machine [type=]name[,prop=value[,...]]``
  43    Select the emulated machine by name. Use ``-machine help`` to list
  44    available machines.
  46    For architectures which aim to support live migration compatibility
  47    across releases, each release will introduce a new versioned machine
  48    type. For example, the 2.8.0 release introduced machine types
  49    "pc-i440fx-2.8" and "pc-q35-2.8" for the x86\_64/i686 architectures.
  51    To allow live migration of guests from QEMU version 2.8.0, to QEMU
  52    version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8"
  53    and "pc-q35-2.8" machines too. To allow users live migrating VMs to
  54    skip multiple intermediate releases when upgrading, new releases of
  55    QEMU will support machine types from many previous versions.
  57    Supported machine properties are:
  59    ``accel=accels1[:accels2[:...]]``
  60        This is used to enable an accelerator. Depending on the target
  61        architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available.
  62        By default, tcg is used. If there is more than one accelerator
  63        specified, the next one is used if the previous one fails to
  64        initialize.
  66    ``vmport=on|off|auto``
  67        Enables emulation of VMWare IO port, for vmmouse etc. auto says
  68        to select the value based on accel. For accel=xen the default is
  69        off otherwise the default is on.
  71    ``dump-guest-core=on|off``
  72        Include guest memory in a core dump. The default is on.
  74    ``mem-merge=on|off``
  75        Enables or disables memory merge support. This feature, when
  76        supported by the host, de-duplicates identical memory pages
  77        among VMs instances (enabled by default).
  79    ``aes-key-wrap=on|off``
  80        Enables or disables AES key wrapping support on s390-ccw hosts.
  81        This feature controls whether AES wrapping keys will be created
  82        to allow execution of AES cryptographic functions. The default
  83        is on.
  85    ``dea-key-wrap=on|off``
  86        Enables or disables DEA key wrapping support on s390-ccw hosts.
  87        This feature controls whether DEA wrapping keys will be created
  88        to allow execution of DEA cryptographic functions. The default
  89        is on.
  91    ``nvdimm=on|off``
  92        Enables or disables NVDIMM support. The default is off.
  94    ``memory-encryption=``
  95        Memory encryption object to use. The default is none.
  97    ``hmat=on|off``
  98        Enables or disables ACPI Heterogeneous Memory Attribute Table
  99        (HMAT) support. The default is off.
 101    ``memory-backend='id'``
 102        An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options.
 103        Allows to use a memory backend as main RAM.
 105        For example:
 106        ::
 108            -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on
 109            -machine memory-backend=pc.ram
 110            -m 512M
 112        Migration compatibility note:
 114        * as backend id one shall use value of 'default-ram-id', advertised by
 115          machine type (available via ``query-machines`` QMP command), if migration
 116          to/from old QEMU (<5.0) is expected.
 117        * for machine types 4.0 and older, user shall
 118          use ``x-use-canonical-path-for-ramblock-id=off`` backend option
 119          if migration to/from old QEMU (<5.0) is expected.
 121        For example:
 122        ::
 124            -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off
 125            -machine memory-backend=pc.ram
 126            -m 512M
 129HXCOMM Deprecated by -machine
 132DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
 133    "-cpu cpu        select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
 135``-cpu model``
 136    Select CPU model (``-cpu help`` for list and additional feature
 137    selection)
 140DEF("accel", HAS_ARG, QEMU_OPTION_accel,
 141    "-accel [accel=]accelerator[,prop[=value][,...]]\n"
 142    "                select accelerator (kvm, xen, hax, hvf, nvmm, whpx or tcg; use 'help' for a list)\n"
 143    "                igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
 144    "                kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
 145    "                kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
 146    "                split-wx=on|off (enable TCG split w^x mapping)\n"
 147    "                tb-size=n (TCG translation block cache size)\n"
 148    "                dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n"
 149    "                thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
 151``-accel name[,prop=value[,...]]``
 152    This is used to enable an accelerator. Depending on the target
 153    architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available. By
 154    default, tcg is used. If there is more than one accelerator
 155    specified, the next one is used if the previous one fails to
 156    initialize.
 158    ``igd-passthru=on|off``
 159        When Xen is in use, this option controls whether Intel
 160        integrated graphics devices can be passed through to the guest
 161        (default=off)
 163    ``kernel-irqchip=on|off|split``
 164        Controls KVM in-kernel irqchip support. The default is full
 165        acceleration of the interrupt controllers. On x86, split irqchip
 166        reduces the kernel attack surface, at a performance cost for
 167        non-MSI interrupts. Disabling the in-kernel irqchip completely
 168        is not recommended except for debugging purposes.
 170    ``kvm-shadow-mem=size``
 171        Defines the size of the KVM shadow MMU.
 173    ``split-wx=on|off``
 174        Controls the use of split w^x mapping for the TCG code generation
 175        buffer. Some operating systems require this to be enabled, and in
 176        such a case this will default on. On other operating systems, this
 177        will default off, but one may enable this for testing or debugging.
 179    ``tb-size=n``
 180        Controls the size (in MiB) of the TCG translation block cache.
 182    ``thread=single|multi``
 183        Controls number of TCG threads. When the TCG is multi-threaded
 184        there will be one thread per vCPU therefore taking advantage of
 185        additional host cores. The default is to enable multi-threading
 186        where both the back-end and front-ends support it and no
 187        incompatible TCG features have been enabled (e.g.
 188        icount/replay).
 190    ``dirty-ring-size=n``
 191        When the KVM accelerator is used, it controls the size of the per-vCPU
 192        dirty page ring buffer (number of entries for each vCPU). It should
 193        be a value that is power of two, and it should be 1024 or bigger (but
 194        still less than the maximum value that the kernel supports).  4096
 195        could be a good initial value if you have no idea which is the best.
 196        Set this value to 0 to disable the feature.  By default, this feature
 197        is disabled (dirty-ring-size=0).  When enabled, KVM will instead
 198        record dirty pages in a bitmap.
 202DEF("smp", HAS_ARG, QEMU_OPTION_smp,
 203    "-smp [[cpus=]n][,maxcpus=cpus][,sockets=sockets][,dies=dies][,cores=cores][,threads=threads]\n"
 204    "                set the number of CPUs to 'n' [default=1]\n"
 205    "                maxcpus= maximum number of total CPUs, including\n"
 206    "                offline CPUs for hotplug, etc\n"
 207    "                sockets= number of discrete sockets in the system\n"
 208    "                dies= number of CPU dies on one socket (for PC only)\n"
 209    "                cores= number of CPU cores on one socket (for PC, it's on one die)\n"
 210    "                threads= number of threads on one CPU core\n",
 211        QEMU_ARCH_ALL)
 213``-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,cores=cores][,threads=threads]``
 214    Simulate a SMP system with '\ ``n``\ ' CPUs initially present on
 215    the machine type board. On boards supporting CPU hotplug, the optional
 216    '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be
 217    added at runtime. If omitted the maximum number of CPUs will be
 218    set to match the initial CPU count. Both parameters are subject to
 219    an upper limit that is determined by the specific machine type chosen.
 221    To control reporting of CPU topology information, the number of sockets,
 222    dies per socket, cores per die, and threads per core can be specified.
 223    The sum `` sockets * cores * dies * threads `` must be equal to the
 224    maximum CPU count. CPU targets may only support a subset of the topology
 225    parameters. Where a CPU target does not support use of a particular
 226    topology parameter, its value should be assumed to be 1 for the purpose
 227    of computing the CPU maximum count.
 229    Either the initial CPU count, or at least one of the topology parameters
 230    must be specified. Values for any omitted parameters will be computed
 231    from those which are given. Historically preference was given to the
 232    coarsest topology parameters when computing missing values (ie sockets
 233    preferred over cores, which were preferred over threads), however, this
 234    behaviour is considered liable to change.
 237DEF("numa", HAS_ARG, QEMU_OPTION_numa,
 238    "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
 239    "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
 240    "-numa dist,src=source,dst=destination,val=distance\n"
 241    "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
 242    "-numa hmat-lb,initiator=node,target=node,hierarchy=memory|first-level|second-level|third-level,data-type=access-latency|read-latency|write-latency[,latency=lat][,bandwidth=bw]\n"
 243    "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
 244    QEMU_ARCH_ALL)
 246``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
 247  \ 
 248``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
 249  \
 250``-numa dist,src=source,dst=destination,val=distance``
 251  \ 
 252``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]``
 253  \ 
 254``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]``
 255  \ 
 256``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]``
 257    Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA
 258    distance from a source node to a destination node. Set the ACPI
 259    Heterogeneous Memory Attributes for the given nodes.
 261    Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and
 262    lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a
 263    contiguous range of CPU indexes (or a single VCPU if lastcpu is
 264    omitted). A non-contiguous set of VCPUs can be represented by
 265    providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is
 266    omitted on all nodes, VCPUs are automatically split between them.
 268    For example, the following option assigns VCPUs 0, 1, 2 and 5 to a
 269    NUMA node:
 271    ::
 273        -numa node,cpus=0-2,cpus=5
 275    '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option
 276    which uses '\ ``socket-id|core-id|thread-id``\ ' properties to
 277    assign CPU objects to a node using topology layout properties of
 278    CPU. The set of properties is machine specific, and depends on used
 279    machine type/'\ ``smp``\ ' options. It could be queried with
 280    '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ '
 281    property specifies node to which CPU object will be assigned, it's
 282    required for node to be declared with '\ ``node``\ ' option before
 283    it's used with '\ ``cpu``\ ' option.
 285    For example:
 287    ::
 289        -M pc \
 290        -smp 1,sockets=2,maxcpus=2 \
 291        -numa node,nodeid=0 -numa node,nodeid=1 \
 292        -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
 294    Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported
 295    for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from
 296    a given memory backend device to a node. If '\ ``mem``\ ' and
 297    '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them.
 300    '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive.
 301    Furthermore, if one node uses '\ ``memdev``\ ', all of them have to
 302    use it.
 304    '\ ``initiator``\ ' is an additional option that points to an
 305    initiator NUMA node that has best performance (the lowest latency or
 306    largest bandwidth) to this NUMA node. Note that this option can be
 307    set only when the machine property 'hmat' is set to 'on'.
 309    Following example creates a machine with 2 NUMA nodes, node 0 has
 310    CPU. node 1 has only memory, and its initiator is node 0. Note that
 311    because node 0 has CPU, by default the initiator of node 0 is itself
 312    and must be itself.
 314    ::
 316        -machine hmat=on \
 317        -m 2G,slots=2,maxmem=4G \
 318        -object memory-backend-ram,size=1G,id=m0 \
 319        -object memory-backend-ram,size=1G,id=m1 \
 320        -numa node,nodeid=0,memdev=m0 \
 321        -numa node,nodeid=1,memdev=m1,initiator=0 \
 322        -smp 2,sockets=2,maxcpus=2  \
 323        -numa cpu,node-id=0,socket-id=0 \
 324        -numa cpu,node-id=0,socket-id=1
 326    source and destination are NUMA node IDs. distance is the NUMA
 327    distance from source to destination. The distance from a node to
 328    itself is always 10. If any pair of nodes is given a distance, then
 329    all pairs must be given distances. Although, when distances are only
 330    given in one direction for each pair of nodes, then the distances in
 331    the opposite directions are assumed to be the same. If, however, an
 332    asymmetrical pair of distances is given for even one node pair, then
 333    all node pairs must be provided distance values for both directions,
 334    even when they are symmetrical. When a node is unreachable from
 335    another node, set the pair's distance to 255.
 337    Note that the -``numa`` option doesn't allocate any of the specified
 338    resources, it just assigns existing resources to NUMA nodes. This
 339    means that one still has to use the ``-m``, ``-smp`` options to
 340    allocate RAM and VCPUs respectively.
 342    Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
 343    Information between initiator and target NUMA nodes in ACPI
 344    Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can
 345    create memory requests, usually it has one or more processors.
 346    Target NUMA node contains addressable memory.
 348    In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is
 349    the memory hierarchy of the target NUMA node: if hierarchy is
 350    'memory', the structure represents the memory performance; if
 351    hierarchy is 'first-level\|second-level\|third-level', this
 352    structure represents aggregated performance of memory side caches
 353    for each domain. type of 'data-type' is type of data represented by
 354    this structure instance: if 'hierarchy' is 'memory', 'data-type' is
 355    'access\|read\|write' latency or 'access\|read\|write' bandwidth of
 356    the target memory; if 'hierarchy' is
 357    'first-level\|second-level\|third-level', 'data-type' is
 358    'access\|read\|write' hit latency or 'access\|read\|write' hit
 359    bandwidth of the target memory side cache.
 361    lat is latency value in nanoseconds. bw is bandwidth value, the
 362    possible value and units are NUM[M\|G\|T], mean that the bandwidth
 363    value are NUM byte per second (or MB/s, GB/s or TB/s depending on
 364    used suffix). Note that if latency or bandwidth value is 0, means
 365    the corresponding latency or bandwidth information is not provided.
 367    In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory
 368    belongs. size is the size of memory side cache in bytes. level is
 369    the cache level described in this structure, note that the cache
 370    level 0 should not be used with '\ ``hmat-cache``\ ' option.
 371    associativity is the cache associativity, the possible value is
 372    'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
 373    is the write policy. line is the cache Line size in bytes.
 375    For example, the following options describe 2 NUMA nodes. Node 0 has
 376    2 cpus and a ram, node 1 has only a ram. The processors in node 0
 377    access memory in node 0 with access-latency 5 nanoseconds,
 378    access-bandwidth is 200 MB/s; The processors in NUMA node 0 access
 379    memory in NUMA node 1 with access-latency 10 nanoseconds,
 380    access-bandwidth is 100 MB/s. And for memory side cache information,
 381    NUMA node 0 and 1 both have 1 level memory cache, size is 10KB,
 382    policy is write-back, the cache Line size is 8 bytes:
 384    ::
 386        -machine hmat=on \
 387        -m 2G \
 388        -object memory-backend-ram,size=1G,id=m0 \
 389        -object memory-backend-ram,size=1G,id=m1 \
 390        -smp 2 \
 391        -numa node,nodeid=0,memdev=m0 \
 392        -numa node,nodeid=1,memdev=m1,initiator=0 \
 393        -numa cpu,node-id=0,socket-id=0 \
 394        -numa cpu,node-id=0,socket-id=1 \
 395        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
 396        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
 397        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
 398        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
 399        -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
 400        -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
 403DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
 404    "-add-fd fd=fd,set=set[,opaque=opaque]\n"
 405    "                Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
 407``-add-fd fd=fd,set=set[,opaque=opaque]``
 408    Add a file descriptor to an fd set. Valid options are:
 410    ``fd=fd``
 411        This option defines the file descriptor of which a duplicate is
 412        added to fd set. The file descriptor cannot be stdin, stdout, or
 413        stderr.
 415    ``set=set``
 416        This option defines the ID of the fd set to add the file
 417        descriptor to.
 419    ``opaque=opaque``
 420        This option defines a free-form string that can be used to
 421        describe fd.
 423    You can open an image using pre-opened file descriptors from an fd
 424    set:
 426    .. parsed-literal::
 428        |qemu_system| \\
 429         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
 430         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
 431         -drive file=/dev/fdset/2,index=0,media=disk
 434DEF("set", HAS_ARG, QEMU_OPTION_set,
 435    "-set group.id.arg=value\n"
 436    "                set <arg> parameter for item <id> of type <group>\n"
 437    "                i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
 439``-set group.id.arg=value``
 440    Set parameter arg for item id of type group
 443DEF("global", HAS_ARG, QEMU_OPTION_global,
 444    "-global driver.property=value\n"
 445    "-global driver=driver,property=property,value=value\n"
 446    "                set a global default for a driver property\n",
 447    QEMU_ARCH_ALL)
 449``-global driver.prop=value``
 450  \ 
 451``-global driver=driver,property=property,value=value``
 452    Set default value of driver's property prop to value, e.g.:
 454    .. parsed-literal::
 456        |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img
 458    In particular, you can use this to set driver properties for devices
 459    which are created automatically by the machine model. To create a
 460    device which is not created automatically and set properties on it,
 461    use -``device``.
 463    -global driver.prop=value is shorthand for -global
 464    driver=driver,property=prop,value=value. The longhand syntax works
 465    even when driver contains a dot.
 468DEF("boot", HAS_ARG, QEMU_OPTION_boot,
 469    "-boot [order=drives][,once=drives][,menu=on|off]\n"
 470    "      [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
 471    "                'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
 472    "                'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
 473    "                'sp_time': the period that splash picture last if menu=on, unit is ms\n"
 474    "                'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
 475    QEMU_ARCH_ALL)
 477``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
 478    Specify boot order drives as a string of drive letters. Valid drive
 479    letters depend on the target architecture. The x86 PC uses: a, b
 480    (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
 481    (Etherboot from network adapter 1-4), hard disk boot is the default.
 482    To apply a particular boot order only on the first startup, specify
 483    it via ``once``. Note that the ``order`` or ``once`` parameter
 484    should not be used together with the ``bootindex`` property of
 485    devices, since the firmware implementations normally do not support
 486    both at the same time.
 488    Interactive boot menus/prompts can be enabled via ``menu=on`` as far
 489    as firmware/BIOS supports them. The default is non-interactive boot.
 491    A splash picture could be passed to bios, enabling user to show it
 492    as logo, when option splash=sp\_name is given and menu=on, If
 493    firmware/BIOS supports them. Currently Seabios for X86 system
 494    support it. limitation: The splash file could be a jpeg file or a
 495    BMP file in 24 BPP format(true color). The resolution should be
 496    supported by the SVGA mode, so the recommended is 320x240, 640x480,
 497    800x640.
 499    A timeout could be passed to bios, guest will pause for rb\_timeout
 500    ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
 501    not reboot, qemu passes '-1' to bios by default. Currently Seabios
 502    for X86 system support it.
 504    Do strict boot via ``strict=on`` as far as firmware/BIOS supports
 505    it. This only effects when boot priority is changed by bootindex
 506    options. The default is non-strict boot.
 508    .. parsed-literal::
 510        # try to boot from network first, then from hard disk
 511        |qemu_system_x86| -boot order=nc
 512        # boot from CD-ROM first, switch back to default order after reboot
 513        |qemu_system_x86| -boot once=d
 514        # boot with a splash picture for 5 seconds.
 515        |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000
 517    Note: The legacy format '-boot drives' is still supported but its
 518    use is discouraged as it may be removed from future versions.
 522    "-m [size=]megs[,slots=n,maxmem=size]\n"
 523    "                configure guest RAM\n"
 524    "                size: initial amount of guest memory\n"
 525    "                slots: number of hotplug slots (default: none)\n"
 526    "                maxmem: maximum amount of guest memory (default: none)\n"
 527    "NOTE: Some architectures might enforce a specific granularity\n",
 528    QEMU_ARCH_ALL)
 530``-m [size=]megs[,slots=n,maxmem=size]``
 531    Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
 532    Optionally, a suffix of "M" or "G" can be used to signify a value in
 533    megabytes or gigabytes respectively. Optional pair slots, maxmem
 534    could be used to set amount of hotpluggable memory slots and maximum
 535    amount of memory. Note that maxmem must be aligned to the page size.
 537    For example, the following command-line sets the guest startup RAM
 538    size to 1GB, creates 3 slots to hotplug additional memory and sets
 539    the maximum memory the guest can reach to 4GB:
 541    .. parsed-literal::
 543        |qemu_system| -m 1G,slots=3,maxmem=4G
 545    If slots and maxmem are not specified, memory hotplug won't be
 546    enabled and the guest startup RAM will never increase.
 549DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
 550    "-mem-path FILE  provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
 552``-mem-path path``
 553    Allocate guest RAM from a temporarily created file in path.
 556DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
 557    "-mem-prealloc   preallocate guest memory (use with -mem-path)\n",
 558    QEMU_ARCH_ALL)
 561    Preallocate memory when using -mem-path.
 565    "-k language     use keyboard layout (for example 'fr' for French)\n",
 566    QEMU_ARCH_ALL)
 568``-k language``
 569    Use keyboard layout language (for example ``fr`` for French). This
 570    option is only needed where it is not easy to get raw PC keycodes
 571    (e.g. on Macs, with some X11 servers or with a VNC or curses
 572    display). You don't normally need to use it on PC/Linux or
 573    PC/Windows hosts.
 575    The available layouts are:
 577    ::
 579        ar  de-ch  es  fo     fr-ca  hu  ja  mk     no  pt-br  sv
 580        da  en-gb  et  fr     fr-ch  is  lt  nl     pl  ru     th
 581        de  en-us  fi  fr-be  hr     it  lv  nl-be  pt  sl     tr
 583    The default is ``en-us``.
 587HXCOMM Deprecated by -audiodev
 588DEF("audio-help", 0, QEMU_OPTION_audio_help,
 589    "-audio-help     show -audiodev equivalent of the currently specified audio settings\n",
 590    QEMU_ARCH_ALL)
 593    Will show the -audiodev equivalent of the currently specified
 594    (deprecated) environment variables.
 597DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
 598    "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
 599    "                specifies the audio backend to use\n"
 600    "                id= identifier of the backend\n"
 601    "                timer-period= timer period in microseconds\n"
 602    "                in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
 603    "                in|out.fixed-settings= use fixed settings for host audio\n"
 604    "                in|out.frequency= frequency to use with fixed settings\n"
 605    "                in|out.channels= number of channels to use with fixed settings\n"
 606    "                in|out.format= sample format to use with fixed settings\n"
 607    "                valid values: s8, s16, s32, u8, u16, u32, f32\n"
 608    "                in|out.voices= number of voices to use\n"
 609    "                in|out.buffer-length= length of buffer in microseconds\n"
 610    "-audiodev none,id=id,[,prop[=value][,...]]\n"
 611    "                dummy driver that discards all output\n"
 613    "-audiodev alsa,id=id[,prop[=value][,...]]\n"
 614    "                in|out.dev= name of the audio device to use\n"
 615    "                in|out.period-length= length of period in microseconds\n"
 616    "                in|out.try-poll= attempt to use poll mode\n"
 617    "                threshold= threshold (in microseconds) when playback starts\n"
 620    "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
 621    "                in|out.buffer-count= number of buffers\n"
 624    "-audiodev dsound,id=id[,prop[=value][,...]]\n"
 625    "                latency= add extra latency to playback in microseconds\n"
 628    "-audiodev oss,id=id[,prop[=value][,...]]\n"
 629    "                in|out.dev= path of the audio device to use\n"
 630    "                in|out.buffer-count= number of buffers\n"
 631    "                in|out.try-poll= attempt to use poll mode\n"
 632    "                try-mmap= try using memory mapped access\n"
 633    "                exclusive= open device in exclusive mode\n"
 634    "                dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
 636#ifdef CONFIG_AUDIO_PA
 637    "-audiodev pa,id=id[,prop[=value][,...]]\n"
 638    "                server= PulseAudio server address\n"
 639    "                in|out.name= source/sink device name\n"
 640    "                in|out.latency= desired latency in microseconds\n"
 643    "-audiodev sdl,id=id[,prop[=value][,...]]\n"
 644    "                in|out.buffer-count= number of buffers\n"
 646#ifdef CONFIG_SPICE
 647    "-audiodev spice,id=id[,prop[=value][,...]]\n"
 649    "-audiodev wav,id=id[,prop[=value][,...]]\n"
 650    "                path= path of wav file to record\n",
 651    QEMU_ARCH_ALL)
 653``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
 654    Adds a new audio backend driver identified by id. There are global
 655    and driver specific properties. Some values can be set differently
 656    for input and output, they're marked with ``in|out.``. You can set
 657    the input's property with ``in.prop`` and the output's property with
 658    ``out.prop``. For example:
 660    ::
 662        -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
 663        -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
 665    NOTE: parameter validation is known to be incomplete, in many cases
 666    specifying an invalid option causes QEMU to print an error message
 667    and continue emulation without sound.
 669    Valid global options are:
 671    ``id=identifier``
 672        Identifies the audio backend.
 674    ``timer-period=period``
 675        Sets the timer period used by the audio subsystem in
 676        microseconds. Default is 10000 (10 ms).
 678    ``in|out.mixing-engine=on|off``
 679        Use QEMU's mixing engine to mix all streams inside QEMU and
 680        convert audio formats when not supported by the backend. When
 681        off, fixed-settings must be off too. Note that disabling this
 682        option means that the selected backend must support multiple
 683        streams and the audio formats used by the virtual cards,
 684        otherwise you'll get no sound. It's not recommended to disable
 685        this option unless you want to use 5.1 or 7.1 audio, as mixing
 686        engine only supports mono and stereo audio. Default is on.
 688    ``in|out.fixed-settings=on|off``
 689        Use fixed settings for host audio. When off, it will change
 690        based on how the guest opens the sound card. In this case you
 691        must not specify frequency, channels or format. Default is on.
 693    ``in|out.frequency=frequency``
 694        Specify the frequency to use when using fixed-settings. Default
 695        is 44100Hz.
 697    ``in|out.channels=channels``
 698        Specify the number of channels to use when using fixed-settings.
 699        Default is 2 (stereo).
 701    ``in|out.format=format``
 702        Specify the sample format to use when using fixed-settings.
 703        Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
 704        ``u32``, ``f32``. Default is ``s16``.
 706    ``in|out.voices=voices``
 707        Specify the number of voices to use. Default is 1.
 709    ``in|out.buffer-length=usecs``
 710        Sets the size of the buffer in microseconds.
 712``-audiodev none,id=id[,prop[=value][,...]]``
 713    Creates a dummy backend that discards all outputs. This backend has
 714    no backend specific properties.
 716``-audiodev alsa,id=id[,prop[=value][,...]]``
 717    Creates backend using the ALSA. This backend is only available on
 718    Linux.
 720    ALSA specific options are:
 722    ``in|out.dev=device``
 723        Specify the ALSA device to use for input and/or output. Default
 724        is ``default``.
 726    ``in|out.period-length=usecs``
 727        Sets the period length in microseconds.
 729    ``in|out.try-poll=on|off``
 730        Attempt to use poll mode with the device. Default is on.
 732    ``threshold=threshold``
 733        Threshold (in microseconds) when playback starts. Default is 0.
 735``-audiodev coreaudio,id=id[,prop[=value][,...]]``
 736    Creates a backend using Apple's Core Audio. This backend is only
 737    available on Mac OS and only supports playback.
 739    Core Audio specific options are:
 741    ``in|out.buffer-count=count``
 742        Sets the count of the buffers.
 744``-audiodev dsound,id=id[,prop[=value][,...]]``
 745    Creates a backend using Microsoft's DirectSound. This backend is
 746    only available on Windows and only supports playback.
 748    DirectSound specific options are:
 750    ``latency=usecs``
 751        Add extra usecs microseconds latency to playback. Default is
 752        10000 (10 ms).
 754``-audiodev oss,id=id[,prop[=value][,...]]``
 755    Creates a backend using OSS. This backend is available on most
 756    Unix-like systems.
 758    OSS specific options are:
 760    ``in|out.dev=device``
 761        Specify the file name of the OSS device to use. Default is
 762        ``/dev/dsp``.
 764    ``in|out.buffer-count=count``
 765        Sets the count of the buffers.
 767    ``in|out.try-poll=on|of``
 768        Attempt to use poll mode with the device. Default is on.
 770    ``try-mmap=on|off``
 771        Try using memory mapped device access. Default is off.
 773    ``exclusive=on|off``
 774        Open the device in exclusive mode (vmix won't work in this
 775        case). Default is off.
 777    ``dsp-policy=policy``
 778        Sets the timing policy (between 0 and 10, where smaller number
 779        means smaller latency but higher CPU usage). Use -1 to use
 780        buffer sizes specified by ``buffer`` and ``buffer-count``. This
 781        option is ignored if you do not have OSS 4. Default is 5.
 783``-audiodev pa,id=id[,prop[=value][,...]]``
 784    Creates a backend using PulseAudio. This backend is available on
 785    most systems.
 787    PulseAudio specific options are:
 789    ``server=server``
 790        Sets the PulseAudio server to connect to.
 792    ``in|out.name=sink``
 793        Use the specified source/sink for recording/playback.
 795    ``in|out.latency=usecs``
 796        Desired latency in microseconds. The PulseAudio server will try
 797        to honor this value but actual latencies may be lower or higher.
 799``-audiodev sdl,id=id[,prop[=value][,...]]``
 800    Creates a backend using SDL. This backend is available on most
 801    systems, but you should use your platform's native backend if
 802    possible.
 804    SDL specific options are:
 806    ``in|out.buffer-count=count``
 807        Sets the count of the buffers.
 809``-audiodev spice,id=id[,prop[=value][,...]]``
 810    Creates a backend that sends audio through SPICE. This backend
 811    requires ``-spice`` and automatically selected in that case, so
 812    usually you can ignore this option. This backend has no backend
 813    specific properties.
 815``-audiodev wav,id=id[,prop[=value][,...]]``
 816    Creates a backend that writes audio to a WAV file.
 818    Backend specific options are:
 820    ``path=path``
 821        Write recorded audio into the specified file. Default is
 822        ``qemu.wav``.
 825DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
 826    "-soundhw c1,... enable audio support\n"
 827    "                and only specified sound cards (comma separated list)\n"
 828    "                use '-soundhw help' to get the list of supported cards\n"
 829    "                use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
 831``-soundhw card1[,card2,...] or -soundhw all``
 832    Enable audio and selected sound hardware. Use 'help' to print all
 833    available sound hardware. For example:
 835    .. parsed-literal::
 837        |qemu_system_x86| -soundhw sb16,adlib disk.img
 838        |qemu_system_x86| -soundhw es1370 disk.img
 839        |qemu_system_x86| -soundhw ac97 disk.img
 840        |qemu_system_x86| -soundhw hda disk.img
 841        |qemu_system_x86| -soundhw all disk.img
 842        |qemu_system_x86| -soundhw help
 844    Note that Linux's i810\_audio OSS kernel (for AC97) module might
 845    require manually specifying clocking.
 847    ::
 849        modprobe i810_audio clocking=48000
 852DEF("device", HAS_ARG, QEMU_OPTION_device,
 853    "-device driver[,prop[=value][,...]]\n"
 854    "                add device (based on driver)\n"
 855    "                prop=value,... sets driver properties\n"
 856    "                use '-device help' to print all possible drivers\n"
 857    "                use '-device driver,help' to print all possible properties\n",
 858    QEMU_ARCH_ALL)
 860``-device driver[,prop[=value][,...]]``
 861    Add device driver. prop=value sets driver properties. Valid
 862    properties depend on the driver. To get help on possible drivers and
 863    properties, use ``-device help`` and ``-device driver,help``.
 865    Some drivers are:
 867``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]``
 868    Add an IPMI BMC. This is a simulation of a hardware management
 869    interface processor that normally sits on a system. It provides a
 870    watchdog and the ability to reset and power control the system. You
 871    need to connect this to an IPMI interface to make it useful
 873    The IPMI slave address to use for the BMC. The default is 0x20. This
 874    address is the BMC's address on the I2C network of management
 875    controllers. If you don't know what this means, it is safe to ignore
 876    it.
 878    ``id=id``
 879        The BMC id for interfaces to use this device.
 881    ``slave_addr=val``
 882        Define slave address to use for the BMC. The default is 0x20.
 884    ``sdrfile=file``
 885        file containing raw Sensor Data Records (SDR) data. The default
 886        is none.
 888    ``fruareasize=val``
 889        size of a Field Replaceable Unit (FRU) area. The default is
 890        1024.
 892    ``frudatafile=file``
 893        file containing raw Field Replaceable Unit (FRU) inventory data.
 894        The default is none.
 896    ``guid=uuid``
 897        value for the GUID for the BMC, in standard UUID format. If this
 898        is set, get "Get GUID" command to the BMC will return it.
 899        Otherwise "Get GUID" will return an error.
 901``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
 902    Add a connection to an external IPMI BMC simulator. Instead of
 903    locally emulating the BMC like the above item, instead connect to an
 904    external entity that provides the IPMI services.
 906    A connection is made to an external BMC simulator. If you do this,
 907    it is strongly recommended that you use the "reconnect=" chardev
 908    option to reconnect to the simulator if the connection is lost. Note
 909    that if this is not used carefully, it can be a security issue, as
 910    the interface has the ability to send resets, NMIs, and power off
 911    the VM. It's best if QEMU makes a connection to an external
 912    simulator running on a secure port on localhost, so neither the
 913    simulator nor QEMU is exposed to any outside network.
 915    See the "lanserv/README.vm" file in the OpenIPMI library for more
 916    details on the external interface.
 918``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
 919    Add a KCS IPMI interafce on the ISA bus. This also adds a
 920    corresponding ACPI and SMBIOS entries, if appropriate.
 922    ``bmc=id``
 923        The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
 924        above.
 926    ``ioport=val``
 927        Define the I/O address of the interface. The default is 0xca0
 928        for KCS.
 930    ``irq=val``
 931        Define the interrupt to use. The default is 5. To disable
 932        interrupts, set this to 0.
 934``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
 935    Like the KCS interface, but defines a BT interface. The default port
 936    is 0xe4 and the default interrupt is 5.
 938``-device pci-ipmi-kcs,bmc=id``
 939    Add a KCS IPMI interafce on the PCI bus.
 941    ``bmc=id``
 942        The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
 944``-device pci-ipmi-bt,bmc=id``
 945    Like the KCS interface, but defines a BT interface on the PCI bus.
 947``-device intel-iommu[,option=...]``
 948    This is only supported by ``-machine q35``, which will enable Intel VT-d
 949    emulation within the guest.  It supports below options:
 951    ``intremap=on|off`` (default: auto)
 952        This enables interrupt remapping feature.  It's required to enable
 953        complete x2apic.  Currently it only supports kvm kernel-irqchip modes
 954        ``off`` or ``split``, while full kernel-irqchip is not yet supported.
 955        The default value is "auto", which will be decided by the mode of
 956        kernel-irqchip.
 958    ``caching-mode=on|off`` (default: off)
 959        This enables caching mode for the VT-d emulated device.  When
 960        caching-mode is enabled, each guest DMA buffer mapping will generate an
 961        IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in
 962        a synchronous way.  It is required for ``-device vfio-pci`` to work
 963        with the VT-d device, because host assigned devices requires to setup
 964        the DMA mapping on the host before guest DMA starts.
 966    ``device-iotlb=on|off`` (default: off)
 967        This enables device-iotlb capability for the emulated VT-d device.  So
 968        far virtio/vhost should be the only real user for this parameter,
 969        paired with ats=on configured for the device.
 971    ``aw-bits=39|48`` (default: 39)
 972        This decides the address width of IOVA address space.  The address
 973        space has 39 bits width for 3-level IOMMU page tables, and 48 bits for
 974        4-level IOMMU page tables.
 976    Please also refer to the wiki page for general scenarios of VT-d
 977    emulation in QEMU: https://wiki.qemu.org/Features/VT-d.
 981DEF("name", HAS_ARG, QEMU_OPTION_name,
 982    "-name string1[,process=string2][,debug-threads=on|off]\n"
 983    "                set the name of the guest\n"
 984    "                string1 sets the window title and string2 the process name\n"
 985    "                When debug-threads is enabled, individual threads are given a separate name\n"
 986    "                NOTE: The thread names are for debugging and not a stable API.\n",
 987    QEMU_ARCH_ALL)
 989``-name name``
 990    Sets the name of the guest. This name will be displayed in the SDL
 991    window caption. The name will also be used for the VNC server. Also
 992    optionally set the top visible process name in Linux. Naming of
 993    individual threads can also be enabled on Linux to aid debugging.
 996DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
 997    "-uuid %08x-%04x-%04x-%04x-%012x\n"
 998    "                specify machine UUID\n", QEMU_ARCH_ALL)
1000``-uuid uuid``
1001    Set system UUID.
1006DEFHEADING(Block device options:)
1008DEF("fda", HAS_ARG, QEMU_OPTION_fda,
1009    "-fda/-fdb file  use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
1012``-fda file``
1013  \
1014``-fdb file``
1015    Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in
1016    the System Emulation Users Guide).
1019DEF("hda", HAS_ARG, QEMU_OPTION_hda,
1020    "-hda/-hdb file  use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL)
1022DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
1023    "-hdc/-hdd file  use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL)
1026``-hda file``
1027  \
1028``-hdb file``
1029  \ 
1030``-hdc file``
1031  \ 
1032``-hdd file``
1033    Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images`
1034    chapter in the System Emulation Users Guide).
1037DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
1038    "-cdrom file     use 'file' as IDE cdrom image (cdrom is ide1 master)\n",
1039    QEMU_ARCH_ALL)
1041``-cdrom file``
1042    Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at
1043    the same time). You can use the host CD-ROM by using ``/dev/cdrom``
1044    as filename.
1047DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
1048    "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
1049    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
1050    "          [,read-only=on|off][,auto-read-only=on|off]\n"
1051    "          [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
1052    "          [,driver specific parameters...]\n"
1053    "                configure a block backend\n", QEMU_ARCH_ALL)
1055``-blockdev option[,option[,option[,...]]]``
1056    Define a new block driver node. Some of the options apply to all
1057    block drivers, other options are only accepted for a specific block
1058    driver. See below for a list of generic options and options for the
1059    most common block drivers.
1061    Options that expect a reference to another node (e.g. ``file``) can
1062    be given in two ways. Either you specify the node name of an already
1063    existing node (file=node-name), or you define a new node inline,
1064    adding options for the referenced node after a dot
1065    (file.filename=path,file.aio=native).
1067    A block driver node created with ``-blockdev`` can be used for a
1068    guest device by specifying its node name for the ``drive`` property
1069    in a ``-device`` argument that defines a block device.
1071    ``Valid options for any block driver node:``
1072        ``driver``
1073            Specifies the block driver to use for the given node.
1075        ``node-name``
1076            This defines the name of the block driver node by which it
1077            will be referenced later. The name must be unique, i.e. it
1078            must not match the name of a different block driver node, or
1079            (if you use ``-drive`` as well) the ID of a drive.
1081            If no node name is specified, it is automatically generated.
1082            The generated node name is not intended to be predictable
1083            and changes between QEMU invocations. For the top level, an
1084            explicit node name must be specified.
1086        ``read-only``
1087            Open the node read-only. Guest write attempts will fail.
1089            Note that some block drivers support only read-only access,
1090            either generally or in certain configurations. In this case,
1091            the default value ``read-only=off`` does not work and the
1092            option must be specified explicitly.
1094        ``auto-read-only``
1095            If ``auto-read-only=on`` is set, QEMU may fall back to
1096            read-only usage even when ``read-only=off`` is requested, or
1097            even switch between modes as needed, e.g. depending on
1098            whether the image file is writable or whether a writing user
1099            is attached to the node.
1101        ``force-share``
1102            Override the image locking system of QEMU by forcing the
1103            node to utilize weaker shared access for permissions where
1104            it would normally request exclusive access. When there is
1105            the potential for multiple instances to have the same file
1106            open (whether this invocation of QEMU is the first or the
1107            second instance), both instances must permit shared access
1108            for the second instance to succeed at opening the file.
1110            Enabling ``force-share=on`` requires ``read-only=on``.
1112        ``cache.direct``
1113            The host page cache can be avoided with ``cache.direct=on``.
1114            This will attempt to do disk IO directly to the guest's
1115            memory. QEMU may still perform an internal copy of the data.
1117        ``cache.no-flush``
1118            In case you don't care about data integrity over host
1119            failures, you can use ``cache.no-flush=on``. This option
1120            tells QEMU that it never needs to write any data to the disk
1121            but can instead keep things in cache. If anything goes
1122            wrong, like your host losing power, the disk storage getting
1123            disconnected accidentally, etc. your image will most
1124            probably be rendered unusable.
1126        ``discard=discard``
1127            discard is one of "ignore" (or "off") or "unmap" (or "on")
1128            and controls whether ``discard`` (also known as ``trim`` or
1129            ``unmap``) requests are ignored or passed to the filesystem.
1130            Some machine types may not support discard requests.
1132        ``detect-zeroes=detect-zeroes``
1133            detect-zeroes is "off", "on" or "unmap" and enables the
1134            automatic conversion of plain zero writes by the OS to
1135            driver specific optimized zero write commands. You may even
1136            choose "unmap" if discard is set to "unmap" to allow a zero
1137            write to be converted to an ``unmap`` operation.
1139    ``Driver-specific options for file``
1140        This is the protocol-level block driver for accessing regular
1141        files.
1143        ``filename``
1144            The path to the image file in the local filesystem
1146        ``aio``
1147            Specifies the AIO backend (threads/native/io_uring,
1148            default: threads)
1150        ``locking``
1151            Specifies whether the image file is protected with Linux OFD
1152            / POSIX locks. The default is to use the Linux Open File
1153            Descriptor API if available, otherwise no lock is applied.
1154            (auto/on/off, default: auto)
1156        Example:
1158        ::
1160            -blockdev driver=file,node-name=disk,filename=disk.img
1162    ``Driver-specific options for raw``
1163        This is the image format block driver for raw images. It is
1164        usually stacked on top of a protocol level block driver such as
1165        ``file``.
1167        ``file``
1168            Reference to or definition of the data source block driver
1169            node (e.g. a ``file`` driver node)
1171        Example 1:
1173        ::
1175            -blockdev driver=file,node-name=disk_file,filename=disk.img
1176            -blockdev driver=raw,node-name=disk,file=disk_file
1178        Example 2:
1180        ::
1182            -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1184    ``Driver-specific options for qcow2``
1185        This is the image format block driver for qcow2 images. It is
1186        usually stacked on top of a protocol level block driver such as
1187        ``file``.
1189        ``file``
1190            Reference to or definition of the data source block driver
1191            node (e.g. a ``file`` driver node)
1193        ``backing``
1194            Reference to or definition of the backing file block device
1195            (default is taken from the image file). It is allowed to
1196            pass ``null`` here in order to disable the default backing
1197            file.
1199        ``lazy-refcounts``
1200            Whether to enable the lazy refcounts feature (on/off;
1201            default is taken from the image file)
1203        ``cache-size``
1204            The maximum total size of the L2 table and refcount block
1205            caches in bytes (default: the sum of l2-cache-size and
1206            refcount-cache-size)
1208        ``l2-cache-size``
1209            The maximum size of the L2 table cache in bytes (default: if
1210            cache-size is not specified - 32M on Linux platforms, and 8M
1211            on non-Linux platforms; otherwise, as large as possible
1212            within the cache-size, while permitting the requested or the
1213            minimal refcount cache size)
1215        ``refcount-cache-size``
1216            The maximum size of the refcount block cache in bytes
1217            (default: 4 times the cluster size; or if cache-size is
1218            specified, the part of it which is not used for the L2
1219            cache)
1221        ``cache-clean-interval``
1222            Clean unused entries in the L2 and refcount caches. The
1223            interval is in seconds. The default value is 600 on
1224            supporting platforms, and 0 on other platforms. Setting it
1225            to 0 disables this feature.
1227        ``pass-discard-request``
1228            Whether discard requests to the qcow2 device should be
1229            forwarded to the data source (on/off; default: on if
1230            discard=unmap is specified, off otherwise)
1232        ``pass-discard-snapshot``
1233            Whether discard requests for the data source should be
1234            issued when a snapshot operation (e.g. deleting a snapshot)
1235            frees clusters in the qcow2 file (on/off; default: on)
1237        ``pass-discard-other``
1238            Whether discard requests for the data source should be
1239            issued on other occasions where a cluster gets freed
1240            (on/off; default: off)
1242        ``overlap-check``
1243            Which overlap checks to perform for writes to the image
1244            (none/constant/cached/all; default: cached). For details or
1245            finer granularity control refer to the QAPI documentation of
1246            ``blockdev-add``.
1248        Example 1:
1250        ::
1252            -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1253            -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1255        Example 2:
1257        ::
1259            -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1261    ``Driver-specific options for other drivers``
1262        Please refer to the QAPI documentation of the ``blockdev-add``
1263        QMP command.
1266DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1267    "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1268    "       [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1269    "       [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1270    "       [,werror=ignore|stop|report|enospc][,id=name]\n"
1271    "       [,aio=threads|native|io_uring]\n"
1272    "       [,readonly=on|off][,copy-on-read=on|off]\n"
1273    "       [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1274    "       [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1275    "       [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1276    "       [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1277    "       [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1278    "       [[,iops_size=is]]\n"
1279    "       [[,group=g]]\n"
1280    "                use 'file' as a drive image\n", QEMU_ARCH_ALL)
1282``-drive option[,option[,option[,...]]]``
1283    Define a new drive. This includes creating a block driver node (the
1284    backend) as well as a guest device, and is mostly a shortcut for
1285    defining the corresponding ``-blockdev`` and ``-device`` options.
1287    ``-drive`` accepts all options that are accepted by ``-blockdev``.
1288    In addition, it knows the following options:
1290    ``file=file``
1291        This option defines which disk image (see the :ref:`disk images`
1292        chapter in the System Emulation Users Guide) to use with this drive.
1293        If the filename contains comma, you must double it (for instance,
1294        "file=my,,file" to use file "my,file").
1296        Special files such as iSCSI devices can be specified using
1297        protocol specific URLs. See the section for "Device URL Syntax"
1298        for more information.
1300    ``if=interface``
1301        This option defines on which type on interface the drive is
1302        connected. Available types are: ide, scsi, sd, mtd, floppy,
1303        pflash, virtio, none.
1305    ``bus=bus,unit=unit``
1306        These options define where is connected the drive by defining
1307        the bus number and the unit id.
1309    ``index=index``
1310        This option defines where is connected the drive by using an
1311        index in the list of available connectors of a given interface
1312        type.
1314    ``media=media``
1315        This option defines the type of the media: disk or cdrom.
1317    ``snapshot=snapshot``
1318        snapshot is "on" or "off" and controls snapshot mode for the
1319        given drive (see ``-snapshot``).
1321    ``cache=cache``
1322        cache is "none", "writeback", "unsafe", "directsync" or
1323        "writethrough" and controls how the host cache is used to access
1324        block data. This is a shortcut that sets the ``cache.direct``
1325        and ``cache.no-flush`` options (as in ``-blockdev``), and
1326        additionally ``cache.writeback``, which provides a default for
1327        the ``write-cache`` option of block guest devices (as in
1328        ``-device``). The modes correspond to the following settings:
1330        =============  ===============   ============   ==============
1331        \              cache.writeback   cache.direct   cache.no-flush
1332        =============  ===============   ============   ==============
1333        writeback      on                off            off
1334        none           on                on             off
1335        writethrough   off               off            off
1336        directsync     off               on             off
1337        unsafe         on                off            on
1338        =============  ===============   ============   ==============
1340        The default mode is ``cache=writeback``.
1342    ``aio=aio``
1343        aio is "threads", "native", or "io_uring" and selects between pthread
1344        based disk I/O, native Linux AIO, or Linux io_uring API.
1346    ``format=format``
1347        Specify which disk format will be used rather than detecting the
1348        format. Can be used to specify format=raw to avoid interpreting
1349        an untrusted format header.
1351    ``werror=action,rerror=action``
1352        Specify which action to take on write and read errors. Valid
1353        actions are: "ignore" (ignore the error and try to continue),
1354        "stop" (pause QEMU), "report" (report the error to the guest),
1355        "enospc" (pause QEMU only if the host disk is full; report the
1356        error to the guest otherwise). The default setting is
1357        ``werror=enospc`` and ``rerror=report``.
1359    ``copy-on-read=copy-on-read``
1360        copy-on-read is "on" or "off" and enables whether to copy read
1361        backing file sectors into the image file.
1363    ``bps=b,bps_rd=r,bps_wr=w``
1364        Specify bandwidth throttling limits in bytes per second, either
1365        for all request types or for reads or writes only. Small values
1366        can lead to timeouts or hangs inside the guest. A safe minimum
1367        for disks is 2 MB/s.
1369    ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
1370        Specify bursts in bytes per second, either for all request types
1371        or for reads or writes only. Bursts allow the guest I/O to spike
1372        above the limit temporarily.
1374    ``iops=i,iops_rd=r,iops_wr=w``
1375        Specify request rate limits in requests per second, either for
1376        all request types or for reads or writes only.
1378    ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
1379        Specify bursts in requests per second, either for all request
1380        types or for reads or writes only. Bursts allow the guest I/O to
1381        spike above the limit temporarily.
1383    ``iops_size=is``
1384        Let every is bytes of a request count as a new request for iops
1385        throttling purposes. Use this option to prevent guests from
1386        circumventing iops limits by sending fewer but larger requests.
1388    ``group=g``
1389        Join a throttling quota group with given name g. All drives that
1390        are members of the same group are accounted for together. Use
1391        this option to prevent guests from circumventing throttling
1392        limits by using many small disks instead of a single larger
1393        disk.
1395    By default, the ``cache.writeback=on`` mode is used. It will report
1396    data writes as completed as soon as the data is present in the host
1397    page cache. This is safe as long as your guest OS makes sure to
1398    correctly flush disk caches where needed. If your guest OS does not
1399    handle volatile disk write caches correctly and your host crashes or
1400    loses power, then the guest may experience data corruption.
1402    For such guests, you should consider using ``cache.writeback=off``.
1403    This means that the host page cache will be used to read and write
1404    data, but write notification will be sent to the guest only after
1405    QEMU has made sure to flush each write to the disk. Be aware that
1406    this has a major impact on performance.
1408    When using the ``-snapshot`` option, unsafe caching is always used.
1410    Copy-on-read avoids accessing the same backing file sectors
1411    repeatedly and is useful when the backing file is over a slow
1412    network. By default copy-on-read is off.
1414    Instead of ``-cdrom`` you can use:
1416    .. parsed-literal::
1418        |qemu_system| -drive file=file,index=2,media=cdrom
1420    Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:
1422    .. parsed-literal::
1424        |qemu_system| -drive file=file,index=0,media=disk
1425        |qemu_system| -drive file=file,index=1,media=disk
1426        |qemu_system| -drive file=file,index=2,media=disk
1427        |qemu_system| -drive file=file,index=3,media=disk
1429    You can open an image using pre-opened file descriptors from an fd
1430    set:
1432    .. parsed-literal::
1434        |qemu_system| \\
1435         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
1436         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
1437         -drive file=/dev/fdset/2,index=0,media=disk
1439    You can connect a CDROM to the slave of ide0:
1441    .. parsed-literal::
1443        |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom
1445    If you don't specify the "file=" argument, you define an empty
1446    drive:
1448    .. parsed-literal::
1450        |qemu_system_x86| -drive if=ide,index=1,media=cdrom
1452    Instead of ``-fda``, ``-fdb``, you can use:
1454    .. parsed-literal::
1456        |qemu_system_x86| -drive file=file,index=0,if=floppy
1457        |qemu_system_x86| -drive file=file,index=1,if=floppy
1459    By default, interface is "ide" and index is automatically
1460    incremented:
1462    .. parsed-literal::
1464        |qemu_system_x86| -drive file=a -drive file=b"
1466    is interpreted like:
1468    .. parsed-literal::
1470        |qemu_system_x86| -hda a -hdb b
1473DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1474    "-mtdblock file  use 'file' as on-board Flash memory image\n",
1475    QEMU_ARCH_ALL)
1477``-mtdblock file``
1478    Use file as on-board Flash memory image.
1481DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1482    "-sd file        use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1484``-sd file``
1485    Use file as SecureDigital card image.
1488DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
1489    "-pflash file    use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
1491``-pflash file``
1492    Use file as a parallel flash image.
1495DEF("snapshot", 0, QEMU_OPTION_snapshot,
1496    "-snapshot       write to temporary files instead of disk image files\n",
1497    QEMU_ARCH_ALL)
1500    Write to temporary files instead of disk image files. In this case,
1501    the raw disk image you use is not written back. You can however
1502    force the write back by pressing C-a s (see the :ref:`disk images`
1503    chapter in the System Emulation Users Guide).
1506DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1507    "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1508    " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n"
1509    " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1510    " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1511    " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1512    " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1513    " [[,throttling.iops-size=is]]\n"
1514    "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n"
1515    "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n"
1516    "-fsdev synth,id=id\n",
1517    QEMU_ARCH_ALL)
1520``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]``
1521  \ 
1522``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]``
1523  \
1524``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]``
1525  \
1526``-fsdev synth,id=id[,readonly=on]``
1527    Define a new file system device. Valid options are:
1529    ``local``
1530        Accesses to the filesystem are done by QEMU.
1532    ``proxy``
1533        Accesses to the filesystem are done by virtfs-proxy-helper(1).
1535    ``synth``
1536        Synthetic filesystem, only used by QTests.
1538    ``id=id``
1539        Specifies identifier for this device.
1541    ``path=path``
1542        Specifies the export path for the file system device. Files
1543        under this path will be available to the 9p client on the guest.
1545    ``security_model=security_model``
1546        Specifies the security model to be used for this export path.
1547        Supported security models are "passthrough", "mapped-xattr",
1548        "mapped-file" and "none". In "passthrough" security model, files
1549        are stored using the same credentials as they are created on the
1550        guest. This requires QEMU to run as root. In "mapped-xattr"
1551        security model, some of the file attributes like uid, gid, mode
1552        bits and link target are stored as file attributes. For
1553        "mapped-file" these attributes are stored in the hidden
1554        .virtfs\_metadata directory. Directories exported by this
1555        security model cannot interact with other unix tools. "none"
1556        security model is same as passthrough except the sever won't
1557        report failures if it fails to set file attributes like
1558        ownership. Security model is mandatory only for local fsdriver.
1559        Other fsdrivers (like proxy) don't take security model as a
1560        parameter.
1562    ``writeout=writeout``
1563        This is an optional argument. The only supported value is
1564        "immediate". This means that host page cache will be used to
1565        read and write data but write notification will be sent to the
1566        guest only when the data has been reported as written by the
1567        storage subsystem.
1569    ``readonly=on``
1570        Enables exporting 9p share as a readonly mount for guests. By
1571        default read-write access is given.
1573    ``socket=socket``
1574        Enables proxy filesystem driver to use passed socket file for
1575        communicating with virtfs-proxy-helper(1).
1577    ``sock_fd=sock_fd``
1578        Enables proxy filesystem driver to use passed socket descriptor
1579        for communicating with virtfs-proxy-helper(1). Usually a helper
1580        like libvirt will create socketpair and pass one of the fds as
1581        sock\_fd.
1583    ``fmode=fmode``
1584        Specifies the default mode for newly created files on the host.
1585        Works only with security models "mapped-xattr" and
1586        "mapped-file".
1588    ``dmode=dmode``
1589        Specifies the default mode for newly created directories on the
1590        host. Works only with security models "mapped-xattr" and
1591        "mapped-file".
1593    ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w``
1594        Specify bandwidth throttling limits in bytes per second, either
1595        for all request types or for reads or writes only.
1597    ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm``
1598        Specify bursts in bytes per second, either for all request types
1599        or for reads or writes only. Bursts allow the guest I/O to spike
1600        above the limit temporarily.
1602    ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w``
1603        Specify request rate limits in requests per second, either for
1604        all request types or for reads or writes only.
1606    ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm``
1607        Specify bursts in requests per second, either for all request
1608        types or for reads or writes only. Bursts allow the guest I/O to
1609        spike above the limit temporarily.
1611    ``throttling.iops-size=is``
1612        Let every is bytes of a request count as a new request for iops
1613        throttling purposes.
1615    -fsdev option is used along with -device driver "virtio-9p-...".
1617``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag``
1618    Options for virtio-9p-... driver are:
1620    ``type``
1621        Specifies the variant to be used. Supported values are "pci",
1622        "ccw" or "device", depending on the machine type.
1624    ``fsdev=id``
1625        Specifies the id value specified along with -fsdev option.
1627    ``mount_tag=mount_tag``
1628        Specifies the tag name to be used by the guest to mount this
1629        export point.
1632DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1633    "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1634    "        [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1635    "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n"
1636    "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n"
1637    "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n",
1638    QEMU_ARCH_ALL)
1641``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]``
1642  \ 
1643``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1644  \ 
1645``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1646  \
1647``-virtfs synth,mount_tag=mount_tag``
1648    Define a new virtual filesystem device and expose it to the guest using
1649    a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain
1650    directory on host is made directly accessible by guest as a pass-through
1651    file system by using the 9P network protocol for communication between
1652    host and guests, if desired even accessible, shared by several guests
1653    simultaniously.
1655    Note that ``-virtfs`` is actually just a convenience shortcut for its
1656    generalized form ``-fsdev -device virtio-9p-pci``.
1658    The general form of pass-through file system options are:
1660    ``local``
1661        Accesses to the filesystem are done by QEMU.
1663    ``proxy``
1664        Accesses to the filesystem are done by virtfs-proxy-helper(1).
1666    ``synth``
1667        Synthetic filesystem, only used by QTests.
1669    ``id=id``
1670        Specifies identifier for the filesystem device
1672    ``path=path``
1673        Specifies the export path for the file system device. Files
1674        under this path will be available to the 9p client on the guest.
1676    ``security_model=security_model``
1677        Specifies the security model to be used for this export path.
1678        Supported security models are "passthrough", "mapped-xattr",
1679        "mapped-file" and "none". In "passthrough" security model, files
1680        are stored using the same credentials as they are created on the
1681        guest. This requires QEMU to run as root. In "mapped-xattr"
1682        security model, some of the file attributes like uid, gid, mode
1683        bits and link target are stored as file attributes. For
1684        "mapped-file" these attributes are stored in the hidden
1685        .virtfs\_metadata directory. Directories exported by this
1686        security model cannot interact with other unix tools. "none"
1687        security model is same as passthrough except the sever won't
1688        report failures if it fails to set file attributes like
1689        ownership. Security model is mandatory only for local fsdriver.
1690        Other fsdrivers (like proxy) don't take security model as a
1691        parameter.
1693    ``writeout=writeout``
1694        This is an optional argument. The only supported value is
1695        "immediate". This means that host page cache will be used to
1696        read and write data but write notification will be sent to the
1697        guest only when the data has been reported as written by the
1698        storage subsystem.
1700    ``readonly=on``
1701        Enables exporting 9p share as a readonly mount for guests. By
1702        default read-write access is given.
1704    ``socket=socket``
1705        Enables proxy filesystem driver to use passed socket file for
1706        communicating with virtfs-proxy-helper(1). Usually a helper like
1707        libvirt will create socketpair and pass one of the fds as
1708        sock\_fd.
1710    ``sock_fd``
1711        Enables proxy filesystem driver to use passed 'sock\_fd' as the
1712        socket descriptor for interfacing with virtfs-proxy-helper(1).
1714    ``fmode=fmode``
1715        Specifies the default mode for newly created files on the host.
1716        Works only with security models "mapped-xattr" and
1717        "mapped-file".
1719    ``dmode=dmode``
1720        Specifies the default mode for newly created directories on the
1721        host. Works only with security models "mapped-xattr" and
1722        "mapped-file".
1724    ``mount_tag=mount_tag``
1725        Specifies the tag name to be used by the guest to mount this
1726        export point.
1728    ``multidevs=multidevs``
1729        Specifies how to deal with multiple devices being shared with a
1730        9p export. Supported behaviours are either "remap", "forbid" or
1731        "warn". The latter is the default behaviour on which virtfs 9p
1732        expects only one device to be shared with the same export, and
1733        if more than one device is shared and accessed via the same 9p
1734        export then only a warning message is logged (once) by qemu on
1735        host side. In order to avoid file ID collisions on guest you
1736        should either create a separate virtfs export for each device to
1737        be shared with guests (recommended way) or you might use "remap"
1738        instead which allows you to share multiple devices with only one
1739        export instead, which is achieved by remapping the original
1740        inode numbers from host to guest in a way that would prevent
1741        such collisions. Remapping inodes in such use cases is required
1742        because the original device IDs from host are never passed and
1743        exposed on guest. Instead all files of an export shared with
1744        virtfs always share the same device id on guest. So two files
1745        with identical inode numbers but from actually different devices
1746        on host would otherwise cause a file ID collision and hence
1747        potential misbehaviours on guest. "forbid" on the other hand
1748        assumes like "warn" that only one device is shared by the same
1749        export, however it will not only log a warning message but also
1750        deny access to additional devices on guest. Note though that
1751        "forbid" does currently not block all possible file access
1752        operations (e.g. readdir() would still return entries from other
1753        devices).
1756DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
1757    "-iscsi [user=user][,password=password]\n"
1758    "       [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
1759    "       [,initiator-name=initiator-iqn][,id=target-iqn]\n"
1760    "       [,timeout=timeout]\n"
1761    "                iSCSI session parameters\n", QEMU_ARCH_ALL)
1765    Configure iSCSI session parameters.
1770DEFHEADING(USB convenience options:)
1772DEF("usb", 0, QEMU_OPTION_usb,
1773    "-usb            enable on-board USB host controller (if not enabled by default)\n",
1774    QEMU_ARCH_ALL)
1777    Enable USB emulation on machine types with an on-board USB host
1778    controller (if not enabled by default). Note that on-board USB host
1779    controllers may not support USB 3.0. In this case
1780    ``-device qemu-xhci`` can be used instead on machines with PCI.
1783DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
1784    "-usbdevice name add the host or guest USB device 'name'\n",
1785    QEMU_ARCH_ALL)
1787``-usbdevice devname``
1788    Add the USB device devname, and enable an on-board USB controller
1789    if possible and necessary (just like it can be done via
1790    ``-machine usb=on``). Note that this option is mainly intended for
1791    the user's convenience only. More fine-grained control can be
1792    achieved by selecting a USB host controller (if necessary) and the
1793    desired USB device via the ``-device`` option instead. For example,
1794    instead of using ``-usbdevice mouse`` it is possible to use
1795    ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse
1796    to a USB 3.0 controller instead (at least on machines that support
1797    PCI and do not have an USB controller enabled by default yet).
1798    For more details, see the chapter about
1799    :ref:`Connecting USB devices` in the System Emulation Users Guide.
1800    Possible devices for devname are:
1802    ``braille``
1803        Braille device. This will use BrlAPI to display the braille
1804        output on a real or fake device (i.e. it also creates a
1805        corresponding ``braille`` chardev automatically beside the
1806        ``usb-braille`` USB device).
1808    ``keyboard``
1809        Standard USB keyboard. Will override the PS/2 keyboard (if present).
1811    ``mouse``
1812        Virtual Mouse. This will override the PS/2 mouse emulation when
1813        activated.
1815    ``tablet``
1816        Pointer device that uses absolute coordinates (like a
1817        touchscreen). This means QEMU is able to report the mouse
1818        position without having to grab the mouse. Also overrides the
1819        PS/2 mouse emulation when activated.
1821    ``wacom-tablet``
1822        Wacom PenPartner USB tablet.
1829DEFHEADING(Display options:)
1831DEF("display", HAS_ARG, QEMU_OPTION_display,
1832#if defined(CONFIG_SPICE)
1833    "-display spice-app[,gl=on|off]\n"
1835#if defined(CONFIG_SDL)
1836    "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off][,gl=on|core|es|off]\n"
1837    "            [,show-cursor=on|off][,window-close=on|off]\n"
1839#if defined(CONFIG_GTK)
1840    "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
1841    "            [,show-cursor=on|off][,window-close=on|off]\n"
1843#if defined(CONFIG_VNC)
1844    "-display vnc=<display>[,<optargs>]\n"
1846#if defined(CONFIG_CURSES)
1847    "-display curses[,charset=<encoding>]\n"
1849#if defined(CONFIG_OPENGL)
1850    "-display egl-headless[,rendernode=<file>]\n"
1852    "-display none\n"
1853    "                select display backend type\n"
1854    "                The default display is equivalent to\n                "
1855#if defined(CONFIG_GTK)
1856            "\"-display gtk\"\n"
1857#elif defined(CONFIG_SDL)
1858            "\"-display sdl\"\n"
1859#elif defined(CONFIG_COCOA)
1860            "\"-display cocoa\"\n"
1861#elif defined(CONFIG_VNC)
1862            "\"-vnc localhost:0,to=99,id=default\"\n"
1864            "\"-display none\"\n"
1866    , QEMU_ARCH_ALL)
1868``-display type``
1869    Select type of display to use. This option is a replacement for the
1870    old style -sdl/-curses/... options. Use ``-display help`` to list
1871    the available display types. Valid values for type are
1873    ``spice-app[,gl=on|off]``
1874        Start QEMU as a Spice server and launch the default Spice client
1875        application. The Spice server will redirect the serial consoles
1876        and QEMU monitors. (Since 4.0)
1878    ``sdl``
1879        Display video output via SDL (usually in a separate graphics
1880        window; see the SDL documentation for other possibilities).
1881        Valid parameters are:
1883        ``alt_grab=on|off`` : Use Control+Alt+Shift-g to toggle mouse grabbing
1885        ``ctrl_grab=on|off`` : Use Right-Control-g to toggle mouse grabbing
1887        ``gl=on|off|core|es`` : Use OpenGL for displaying
1889        ``show-cursor=on|off`` :  Force showing the mouse cursor
1891        ``window-close=on|off`` : Allow to quit qemu with window close button
1893    ``gtk``
1894        Display video output in a GTK window. This interface provides
1895        drop-down menus and other UI elements to configure and control
1896        the VM during runtime. Valid parameters are:
1898        ``full-screen=on|off`` : Start in fullscreen mode
1900        ``gl=on|off`` : Use OpenGL for displaying
1902        ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover
1904        ``show-cursor=on|off`` :  Force showing the mouse cursor
1906        ``window-close=on|off`` : Allow to quit qemu with window close button
1908    ``curses[,charset=<encoding>]``
1909        Display video output via curses. For graphics device models
1910        which support a text mode, QEMU can display this output using a
1911        curses/ncurses interface. Nothing is displayed when the graphics
1912        device is in graphical mode or if the graphics device does not
1913        support a text mode. Generally only the VGA device models
1914        support text mode. The font charset used by the guest can be
1915        specified with the ``charset`` option, for example
1916        ``charset=CP850`` for IBM CP850 encoding. The default is
1917        ``CP437``.
1919    ``egl-headless[,rendernode=<file>]``
1920        Offload all OpenGL operations to a local DRI device. For any
1921        graphical display, this display needs to be paired with either
1922        VNC or SPICE displays.
1924    ``vnc=<display>``
1925        Start a VNC server on display <display>
1927    ``none``
1928        Do not display video output. The guest will still see an
1929        emulated graphics card, but its output will not be displayed to
1930        the QEMU user. This option differs from the -nographic option in
1931        that it only affects what is done with video output; -nographic
1932        also changes the destination of the serial and parallel port
1933        data.
1936DEF("nographic", 0, QEMU_OPTION_nographic,
1937    "-nographic      disable graphical output and redirect serial I/Os to console\n",
1938    QEMU_ARCH_ALL)
1941    Normally, if QEMU is compiled with graphical window support, it
1942    displays output such as guest graphics, guest console, and the QEMU
1943    monitor in a window. With this option, you can totally disable
1944    graphical output so that QEMU is a simple command line application.
1945    The emulated serial port is redirected on the console and muxed with
1946    the monitor (unless redirected elsewhere explicitly). Therefore, you
1947    can still use QEMU to debug a Linux kernel with a serial console.
1948    Use C-a h for help on switching between the console and monitor.
1951DEF("curses", 0, QEMU_OPTION_curses,
1952    "-curses         shorthand for -display curses\n",
1953    QEMU_ARCH_ALL)
1956    Normally, if QEMU is compiled with graphical window support, it
1957    displays output such as guest graphics, guest console, and the QEMU
1958    monitor in a window. With this option, QEMU can display the VGA
1959    output when in text mode using a curses/ncurses interface. Nothing
1960    is displayed in graphical mode.
1963DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
1964    "-alt-grab       use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
1965    QEMU_ARCH_ALL)
1968    Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
1969    this also affects the special keys (for fullscreen, monitor-mode
1970    switching, etc).
1973DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
1974    "-ctrl-grab      use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
1975    QEMU_ARCH_ALL)
1978    Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
1979    also affects the special keys (for fullscreen, monitor-mode
1980    switching, etc).
1983DEF("no-quit", 0, QEMU_OPTION_no_quit,
1984    "-no-quit        disable SDL/GTK window close capability (deprecated)\n", QEMU_ARCH_ALL)
1987    Disable window close capability (SDL and GTK only). This option is
1988    deprecated, please use ``-display ...,window-close=off`` instead.
1991DEF("sdl", 0, QEMU_OPTION_sdl,
1992    "-sdl            shorthand for -display sdl\n", QEMU_ARCH_ALL)
1995    Enable SDL.
1998DEF("spice", HAS_ARG, QEMU_OPTION_spice,
1999    "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
2000    "       [,x509-key-file=<file>][,x509-key-password=<file>]\n"
2001    "       [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
2002    "       [,x509-dh-key-file=<file>][,addr=addr]\n"
2003    "       [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n"
2004    "       [,tls-ciphers=<list>]\n"
2005    "       [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
2006    "       [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
2007    "       [,sasl=on|off][,disable-ticketing=on|off]\n"
2008    "       [,password=<string>][,password-secret=<secret-id>]\n"
2009    "       [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
2010    "       [,jpeg-wan-compression=[auto|never|always]]\n"
2011    "       [,zlib-glz-wan-compression=[auto|never|always]]\n"
2012    "       [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n"
2013    "       [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n"
2014    "       [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
2015    "       [,gl=[on|off]][,rendernode=<file>]\n"
2016    "   enable spice\n"
2017    "   at least one of {port, tls-port} is mandatory\n",
2018    QEMU_ARCH_ALL)
2020``-spice option[,option[,...]]``
2021    Enable the spice remote desktop protocol. Valid options are
2023    ``port=<nr>``
2024        Set the TCP port spice is listening on for plaintext channels.
2026    ``addr=<addr>``
2027        Set the IP address spice is listening on. Default is any
2028        address.
2030    ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off``
2031        Force using the specified IP version.
2033    ``password=<string>``
2034        Set the password you need to authenticate.
2036        This option is deprecated and insecure because it leaves the
2037        password visible in the process listing. Use ``password-secret``
2038        instead.
2040    ``password-secret=<secret-id>``
2041        Set the ID of the ``secret`` object containing the password
2042        you need to authenticate.
2044    ``sasl=on|off``
2045        Require that the client use SASL to authenticate with the spice.
2046        The exact choice of authentication method used is controlled
2047        from the system / user's SASL configuration file for the 'qemu'
2048        service. This is typically found in /etc/sasl2/qemu.conf. If
2049        running QEMU as an unprivileged user, an environment variable
2050        SASL\_CONF\_PATH can be used to make it search alternate
2051        locations for the service config. While some SASL auth methods
2052        can also provide data encryption (eg GSSAPI), it is recommended
2053        that SASL always be combined with the 'tls' and 'x509' settings
2054        to enable use of SSL and server certificates. This ensures a
2055        data encryption preventing compromise of authentication
2056        credentials.
2058    ``disable-ticketing=on|off``
2059        Allow client connects without authentication.
2061    ``disable-copy-paste=on|off``
2062        Disable copy paste between the client and the guest.
2064    ``disable-agent-file-xfer=on|off``
2065        Disable spice-vdagent based file-xfer between the client and the
2066        guest.
2068    ``tls-port=<nr>``
2069        Set the TCP port spice is listening on for encrypted channels.
2071    ``x509-dir=<dir>``
2072        Set the x509 file directory. Expects same filenames as -vnc
2073        $display,x509=$dir
2075    ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>``
2076        The x509 file names can also be configured individually.
2078    ``tls-ciphers=<list>``
2079        Specify which ciphers to use.
2081    ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]``
2082        Force specific channel to be used with or without TLS
2083        encryption. The options can be specified multiple times to
2084        configure multiple channels. The special name "default" can be
2085        used to set the default mode. For channels which are not
2086        explicitly forced into one mode the spice client is allowed to
2087        pick tls/plaintext as he pleases.
2089    ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]``
2090        Configure image compression (lossless). Default is auto\_glz.
2092    ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]``
2093        Configure wan image compression (lossy for slow links). Default
2094        is auto.
2096    ``streaming-video=[off|all|filter]``
2097        Configure video stream detection. Default is off.
2099    ``agent-mouse=[on|off]``
2100        Enable/disable passing mouse events via vdagent. Default is on.
2102    ``playback-compression=[on|off]``
2103        Enable/disable audio stream compression (using celt 0.5.1).
2104        Default is on.
2106    ``seamless-migration=[on|off]``
2107        Enable/disable spice seamless migration. Default is off.
2109    ``gl=[on|off]``
2110        Enable/disable OpenGL context. Default is off.
2112    ``rendernode=<file>``
2113        DRM render node for OpenGL rendering. If not specified, it will
2114        pick the first available. (Since 2.9)
2117DEF("portrait", 0, QEMU_OPTION_portrait,
2118    "-portrait       rotate graphical output 90 deg left (only PXA LCD)\n",
2119    QEMU_ARCH_ALL)
2122    Rotate graphical output 90 deg left (only PXA LCD).
2125DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
2126    "-rotate <deg>   rotate graphical output some deg left (only PXA LCD)\n",
2127    QEMU_ARCH_ALL)
2129``-rotate deg``
2130    Rotate graphical output some deg left (only PXA LCD).
2133DEF("vga", HAS_ARG, QEMU_OPTION_vga,
2134    "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
2135    "                select video card type\n", QEMU_ARCH_ALL)
2137``-vga type``
2138    Select type of VGA card to emulate. Valid values for type are
2140    ``cirrus``
2141        Cirrus Logic GD5446 Video card. All Windows versions starting
2142        from Windows 95 should recognize and use this graphic card. For
2143        optimal performances, use 16 bit color depth in the guest and
2144        the host OS. (This card was the default before QEMU 2.2)
2146    ``std``
2147        Standard VGA card with Bochs VBE extensions. If your guest OS
2148        supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
2149        you want to use high resolution modes (>= 1280x1024x16) then you
2150        should use this option. (This card is the default since QEMU
2151        2.2)
2153    ``vmware``
2154        VMWare SVGA-II compatible adapter. Use it if you have
2155        sufficiently recent XFree86/XOrg server or Windows guest with a
2156        driver for this card.
2158    ``qxl``
2159        QXL paravirtual graphic card. It is VGA compatible (including
2160        VESA 2.0 VBE support). Works best with qxl guest drivers
2161        installed though. Recommended choice when using the spice
2162        protocol.
2164    ``tcx``
2165        (sun4m only) Sun TCX framebuffer. This is the default
2166        framebuffer for sun4m machines and offers both 8-bit and 24-bit
2167        colour depths at a fixed resolution of 1024x768.
2169    ``cg3``
2170        (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit
2171        framebuffer for sun4m machines available in both 1024x768
2172        (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people
2173        wishing to run older Solaris versions.
2175    ``virtio``
2176        Virtio VGA card.
2178    ``none``
2179        Disable VGA card.
2182DEF("full-screen", 0, QEMU_OPTION_full_screen,
2183    "-full-screen    start in full screen\n", QEMU_ARCH_ALL)
2186    Start in full screen.
2190    "-g WxH[xDEPTH]  Set the initial graphical resolution and depth\n",
2193``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]``
2194    Set the initial graphical resolution and depth (PPC, SPARC only).
2196    For PPC the default is 800x600x32.
2198    For SPARC with the TCX graphics device, the default is 1024x768x8
2199    with the option of 1024x768x24. For cgthree, the default is
2200    1024x768x8 with the option of 1152x900x8 for people who wish to use
2201    OBP.
2204DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
2205    "-vnc <display>  shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
2207``-vnc display[,option[,option[,...]]]``
2208    Normally, if QEMU is compiled with graphical window support, it
2209    displays output such as guest graphics, guest console, and the QEMU
2210    monitor in a window. With this option, you can have QEMU listen on
2211    VNC display display and redirect the VGA display over the VNC
2212    session. It is very useful to enable the usb tablet device when
2213    using this option (option ``-device usb-tablet``). When using the
2214    VNC display, you must use the ``-k`` parameter to set the keyboard
2215    layout if you are not using en-us. Valid syntax for the display is
2217    ``to=L``
2218        With this option, QEMU will try next available VNC displays,
2219        until the number L, if the origianlly defined "-vnc display" is
2220        not available, e.g. port 5900+display is already used by another
2221        application. By default, to=0.
2223    ``host:d``
2224        TCP connections will only be allowed from host on display d. By
2225        convention the TCP port is 5900+d. Optionally, host can be
2226        omitted in which case the server will accept connections from
2227        any host.
2229    ``unix:path``
2230        Connections will be allowed over UNIX domain sockets where path
2231        is the location of a unix socket to listen for connections on.
2233    ``none``
2234        VNC is initialized but not started. The monitor ``change``
2235        command can be used to later start the VNC server.
2237    Following the display value there may be one or more option flags
2238    separated by commas. Valid options are
2240    ``reverse=on|off``
2241        Connect to a listening VNC client via a "reverse" connection.
2242        The client is specified by the display. For reverse network
2243        connections (host:d,``reverse``), the d argument is a TCP port
2244        number, not a display number.
2246    ``websocket=on|off``
2247        Opens an additional TCP listening port dedicated to VNC
2248        Websocket connections. If a bare websocket option is given, the
2249        Websocket port is 5700+display. An alternative port can be
2250        specified with the syntax ``websocket``\ =port.
2252        If host is specified connections will only be allowed from this
2253        host. It is possible to control the websocket listen address
2254        independently, using the syntax ``websocket``\ =host:port.
2256        If no TLS credentials are provided, the websocket connection
2257        runs in unencrypted mode. If TLS credentials are provided, the
2258        websocket connection requires encrypted client connections.
2260    ``password=on|off``
2261        Require that password based authentication is used for client
2262        connections.
2264        The password must be set separately using the ``set_password``
2265        command in the :ref:`QEMU monitor`. The
2266        syntax to change your password is:
2267        ``set_password <protocol> <password>`` where <protocol> could be
2268        either "vnc" or "spice".
2270        If you would like to change <protocol> password expiration, you
2271        should use ``expire_password <protocol> <expiration-time>``
2272        where expiration time could be one of the following options:
2273        now, never, +seconds or UNIX time of expiration, e.g. +60 to
2274        make password expire in 60 seconds, or 1335196800 to make
2275        password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for
2276        this date and time).
2278        You can also use keywords "now" or "never" for the expiration
2279        time to allow <protocol> password to expire immediately or never
2280        expire.
2282    ``password-secret=<secret-id>``
2283        Require that password based authentication is used for client
2284        connections, using the password provided by the ``secret``
2285        object identified by ``secret-id``.
2287    ``tls-creds=ID``
2288        Provides the ID of a set of TLS credentials to use to secure the
2289        VNC server. They will apply to both the normal VNC server socket
2290        and the websocket socket (if enabled). Setting TLS credentials
2291        will cause the VNC server socket to enable the VeNCrypt auth
2292        mechanism. The credentials should have been previously created
2293        using the ``-object tls-creds`` argument.
2295    ``tls-authz=ID``
2296        Provides the ID of the QAuthZ authorization object against which
2297        the client's x509 distinguished name will validated. This object
2298        is only resolved at time of use, so can be deleted and recreated
2299        on the fly while the VNC server is active. If missing, it will
2300        default to denying access.
2302    ``sasl=on|off``
2303        Require that the client use SASL to authenticate with the VNC
2304        server. The exact choice of authentication method used is
2305        controlled from the system / user's SASL configuration file for
2306        the 'qemu' service. This is typically found in
2307        /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
2308        an environment variable SASL\_CONF\_PATH can be used to make it
2309        search alternate locations for the service config. While some
2310        SASL auth methods can also provide data encryption (eg GSSAPI),
2311        it is recommended that SASL always be combined with the 'tls'
2312        and 'x509' settings to enable use of SSL and server
2313        certificates. This ensures a data encryption preventing
2314        compromise of authentication credentials. See the
2315        :ref:`VNC security` section in the System Emulation Users Guide
2316        for details on using SASL authentication.
2318    ``sasl-authz=ID``
2319        Provides the ID of the QAuthZ authorization object against which
2320        the client's SASL username will validated. This object is only
2321        resolved at time of use, so can be deleted and recreated on the
2322        fly while the VNC server is active. If missing, it will default
2323        to denying access.
2325    ``acl=on|off``
2326        Legacy method for enabling authorization of clients against the
2327        x509 distinguished name and SASL username. It results in the
2328        creation of two ``authz-list`` objects with IDs of
2329        ``vnc.username`` and ``vnc.x509dname``. The rules for these
2330        objects must be configured with the HMP ACL commands.
2332        This option is deprecated and should no longer be used. The new
2333        ``sasl-authz`` and ``tls-authz`` options are a replacement.
2335    ``lossy=on|off``
2336        Enable lossy compression methods (gradient, JPEG, ...). If this
2337        option is set, VNC client may receive lossy framebuffer updates
2338        depending on its encoding settings. Enabling this option can
2339        save a lot of bandwidth at the expense of quality.
2341    ``non-adaptive=on|off``
2342        Disable adaptive encodings. Adaptive encodings are enabled by
2343        default. An adaptive encoding will try to detect frequently
2344        updated screen regions, and send updates in these regions using
2345        a lossy encoding (like JPEG). This can be really helpful to save
2346        bandwidth when playing videos. Disabling adaptive encodings
2347        restores the original static behavior of encodings like Tight.
2349    ``share=[allow-exclusive|force-shared|ignore]``
2350        Set display sharing policy. 'allow-exclusive' allows clients to
2351        ask for exclusive access. As suggested by the rfb spec this is
2352        implemented by dropping other connections. Connecting multiple
2353        clients in parallel requires all clients asking for a shared
2354        session (vncviewer: -shared switch). This is the default.
2355        'force-shared' disables exclusive client access. Useful for
2356        shared desktop sessions, where you don't want someone forgetting
2357        specify -shared disconnect everybody else. 'ignore' completely
2358        ignores the shared flag and allows everybody connect
2359        unconditionally. Doesn't conform to the rfb spec but is
2360        traditional QEMU behavior.
2362    ``key-delay-ms``
2363        Set keyboard delay, for key down and key up events, in
2364        milliseconds. Default is 10. Keyboards are low-bandwidth
2365        devices, so this slowdown can help the device and guest to keep
2366        up and not lose events in case events are arriving in bulk.
2367        Possible causes for the latter are flaky network connections, or
2368        scripts for automated testing.
2370    ``audiodev=audiodev``
2371        Use the specified audiodev when the VNC client requests audio
2372        transmission. When not using an -audiodev argument, this option
2373        must be omitted, otherwise is must be present and specify a
2374        valid audiodev.
2376    ``power-control=on|off``
2377        Permit the remote client to issue shutdown, reboot or reset power
2378        control requests.
2383ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2385DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2386    "-win2k-hack     use it when installing Windows 2000 to avoid a disk full bug\n",
2387    QEMU_ARCH_I386)
2390    Use it when installing Windows 2000 to avoid a disk full bug. After
2391    Windows 2000 is installed, you no longer need this option (this
2392    option slows down the IDE transfers).
2395DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2396    "-no-fd-bootchk  disable boot signature checking for floppy disks\n",
2397    QEMU_ARCH_I386)
2400    Disable boot signature checking for floppy disks in BIOS. May be
2401    needed to boot from old floppy disks.
2404DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
2405           "-no-acpi        disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2408    Disable ACPI (Advanced Configuration and Power Interface) support.
2409    Use it if your guest OS complains about ACPI problems (PC target
2410    machine only).
2413DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
2414    "-no-hpet        disable HPET\n", QEMU_ARCH_I386)
2417    Disable HPET support.
2420DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2421    "-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n][,asl_compiler_id=str][,asl_compiler_rev=n][,{data|file}=file1[:file2]...]\n"
2422    "                ACPI table description\n", QEMU_ARCH_I386)
2424``-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n] [,asl_compiler_id=str][,asl_compiler_rev=n][,data=file1[:file2]...]``
2425    Add ACPI table with specified header fields and context from
2426    specified files. For file=, take whole ACPI table from the specified
2427    files, including all ACPI headers (possible overridden by other
2428    options). For data=, only data portion of the table is used, all
2429    header information is specified in the command line. If a SLIC table
2430    is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
2431    fields will override the same in the RSDT and the FADT (a.k.a.
2432    FACP), in order to ensure the field matches required by the
2433    Microsoft SLIC spec and the ACPI spec.
2436DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2437    "-smbios file=binary\n"
2438    "                load SMBIOS entry from binary file\n"
2439    "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2440    "              [,uefi=on|off]\n"
2441    "                specify SMBIOS type 0 fields\n"
2442    "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2443    "              [,uuid=uuid][,sku=str][,family=str]\n"
2444    "                specify SMBIOS type 1 fields\n"
2445    "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2446    "              [,asset=str][,location=str]\n"
2447    "                specify SMBIOS type 2 fields\n"
2448    "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2449    "              [,sku=str]\n"
2450    "                specify SMBIOS type 3 fields\n"
2451    "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2452    "              [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
2453    "                specify SMBIOS type 4 fields\n"
2454    "-smbios type=11[,value=str][,path=filename]\n"
2455    "                specify SMBIOS type 11 fields\n"
2456    "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2457    "               [,asset=str][,part=str][,speed=%d]\n"
2458    "                specify SMBIOS type 17 fields\n"
2459    "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n"
2460    "                specify SMBIOS type 41 fields\n",
2463``-smbios file=binary``
2464    Load SMBIOS entry from binary file.
2466``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]``
2467    Specify SMBIOS type 0 fields
2469``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]``
2470    Specify SMBIOS type 1 fields
2472``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]``
2473    Specify SMBIOS type 2 fields
2475``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
2476    Specify SMBIOS type 3 fields
2478``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]``
2479    Specify SMBIOS type 4 fields
2481``-smbios type=11[,value=str][,path=filename]``
2482    Specify SMBIOS type 11 fields
2484    This argument can be repeated multiple times, and values are added in the order they are parsed.
2485    Applications intending to use OEM strings data are encouraged to use their application name as
2486    a prefix for the value string. This facilitates passing information for multiple applications
2487    concurrently.
2489    The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax
2490    loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes.
2492    Both the ``value`` and ``path`` options can be repeated multiple times and will be added to
2493    the SMBIOS table in the order in which they appear.
2495    Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535
2496    bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the
2497    guest. Instead it should be used as a indicator to inform the guest where to locate the real
2498    data set, for example, by specifying the serial ID of a block device.
2500    An example passing three strings is
2502    .. parsed-literal::
2504        -smbios type=11,value=cloud-init:ds=nocloud-net;s=,\\
2505                        value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\
2506                        path=/some/file/with/oemstringsdata.txt
2508    In the guest OS this is visible with the ``dmidecode`` command
2510     .. parsed-literal::
2512         $ dmidecode -t 11
2513         Handle 0x0E00, DMI type 11, 5 bytes
2514         OEM Strings
2515              String 1: cloud-init:ds=nocloud-net;s=
2516              String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os
2517              String 3: myapp:some extra data
2520``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]``
2521    Specify SMBIOS type 17 fields
2523``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]``
2524    Specify SMBIOS type 41 fields
2526    This argument can be repeated multiple times.  Its main use is to allow network interfaces be created
2527    as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface
2528    position on the PCI bus.
2530    Here is an example of use:
2532    .. parsed-literal::
2534        -netdev user,id=internet \\
2535        -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\
2536        -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev
2538    In the guest OS, the device should then appear as ``eno1``:
2540    ..parsed-literal::
2542         $ ip -brief l
2543         lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
2544         eno1             UP             50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP>
2546    Currently, the PCI device has to be attached to the root bus.
2552DEFHEADING(Network options:)
2554DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2555#ifdef CONFIG_SLIRP
2556    "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n"
2557    "         [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2558    "         [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2559    "         [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2560    "         [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2561#ifndef _WIN32
2562                                             "[,smb=dir[,smbserver=addr]]\n"
2564    "                configure a user mode network backend with ID 'str',\n"
2565    "                its DHCP server and optional services\n"
2567#ifdef _WIN32
2568    "-netdev tap,id=str,ifname=name\n"
2569    "                configure a host TAP network backend with ID 'str'\n"
2571    "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2572    "         [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2573    "         [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2574    "         [,poll-us=n]\n"
2575    "                configure a host TAP network backend with ID 'str'\n"
2576    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2577    "                use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2578    "                to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2579    "                to deconfigure it\n"
2580    "                use '[down]script=no' to disable script execution\n"
2581    "                use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2582    "                configure it\n"
2583    "                use 'fd=h' to connect to an already opened TAP interface\n"
2584    "                use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2585    "                use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2586    "                default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2587    "                use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2588    "                use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2589    "                use vhost=on to enable experimental in kernel accelerator\n"
2590    "                    (only has effect for virtio guests which use MSIX)\n"
2591    "                use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2592    "                use 'vhostfd=h' to connect to an already opened vhost net device\n"
2593    "                use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2594    "                use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2595    "                use 'poll-us=n' to specify the maximum number of microseconds that could be\n"
2596    "                spent on busy polling for vhost net\n"
2597    "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2598    "                configure a host TAP network backend with ID 'str' that is\n"
2599    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2600    "                using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2602#ifdef __linux__
2603    "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2604    "         [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n"
2605    "         [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n"
2606    "         [,rxcookie=rxcookie][,offset=offset]\n"
2607    "                configure a network backend with ID 'str' connected to\n"
2608    "                an Ethernet over L2TPv3 pseudowire.\n"
2609    "                Linux kernel 3.3+ as well as most routers can talk\n"
2610    "                L2TPv3. This transport allows connecting a VM to a VM,\n"
2611    "                VM to a router and even VM to Host. It is a nearly-universal\n"
2612    "                standard (RFC3931). Note - this implementation uses static\n"
2613    "                pre-configured tunnels (same as the Linux kernel).\n"
2614    "                use 'src=' to specify source address\n"
2615    "                use 'dst=' to specify destination address\n"
2616    "                use 'udp=on' to specify udp encapsulation\n"
2617    "                use 'srcport=' to specify source udp port\n"
2618    "                use 'dstport=' to specify destination udp port\n"
2619    "                use 'ipv6=on' to force v6\n"
2620    "                L2TPv3 uses cookies to prevent misconfiguration as\n"
2621    "                well as a weak security measure\n"
2622    "                use 'rxcookie=0x012345678' to specify a rxcookie\n"
2623    "                use 'txcookie=0x012345678' to specify a txcookie\n"
2624    "                use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2625    "                use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2626    "                use 'pincounter=on' to work around broken counter handling in peer\n"
2627    "                use 'offset=X' to add an extra offset between header and data\n"
2629    "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2630    "                configure a network backend to connect to another network\n"
2631    "                using a socket connection\n"
2632    "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2633    "                configure a network backend to connect to a multicast maddr and port\n"
2634    "                use 'localaddr=addr' to specify the host address to send packets from\n"
2635    "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2636    "                configure a network backend to connect to another network\n"
2637    "                using an UDP tunnel\n"
2638#ifdef CONFIG_VDE
2639    "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2640    "                configure a network backend to connect to port 'n' of a vde switch\n"
2641    "                running on host and listening for incoming connections on 'socketpath'.\n"
2642    "                Use group 'groupname' and mode 'octalmode' to change default\n"
2643    "                ownership and permissions for communication port.\n"
2645#ifdef CONFIG_NETMAP
2646    "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2647    "                attach to the existing netmap-enabled network interface 'name', or to a\n"
2648    "                VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2649    "                netmap device, defaults to '/dev/netmap')\n"
2651#ifdef CONFIG_POSIX
2652    "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2653    "                configure a vhost-user network, backed by a chardev 'dev'\n"
2655#ifdef __linux__
2656    "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n"
2657    "                configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n"
2659    "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2660    "                configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2661DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2662    "-nic [tap|bridge|"
2663#ifdef CONFIG_SLIRP
2664    "user|"
2666#ifdef __linux__
2667    "l2tpv3|"
2669#ifdef CONFIG_VDE
2670    "vde|"
2672#ifdef CONFIG_NETMAP
2673    "netmap|"
2675#ifdef CONFIG_POSIX
2676    "vhost-user|"
2678    "socket][,option][,...][mac=macaddr]\n"
2679    "                initialize an on-board / default host NIC (using MAC address\n"
2680    "                macaddr) and connect it to the given host network backend\n"
2681    "-nic none       use it alone to have zero network devices (the default is to\n"
2682    "                provided a 'user' network connection)\n",
2683    QEMU_ARCH_ALL)
2684DEF("net", HAS_ARG, QEMU_OPTION_net,
2685    "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2686    "                configure or create an on-board (or machine default) NIC and\n"
2687    "                connect it to hub 0 (please use -nic unless you need a hub)\n"
2688    "-net ["
2689#ifdef CONFIG_SLIRP
2690    "user|"
2692    "tap|"
2693    "bridge|"
2694#ifdef CONFIG_VDE
2695    "vde|"
2697#ifdef CONFIG_NETMAP
2698    "netmap|"
2700    "socket][,option][,option][,...]\n"
2701    "                old way to initialize a host network interface\n"
2702    "                (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
2704``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]``
2705    This option is a shortcut for configuring both the on-board
2706    (default) guest NIC hardware and the host network backend in one go.
2707    The host backend options are the same as with the corresponding
2708    ``-netdev`` options below. The guest NIC model can be set with
2709    ``model=modelname``. Use ``model=help`` to list the available device
2710    types. The hardware MAC address can be set with ``mac=macaddr``.
2712    The following two example do exactly the same, to show how ``-nic``
2713    can be used to shorten the command line length:
2715    .. parsed-literal::
2717        |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
2718        |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
2720``-nic none``
2721    Indicate that no network devices should be configured. It is used to
2722    override the default configuration (default NIC with "user" host
2723    network backend) which is activated if no other networking options
2724    are provided.
2726``-netdev user,id=id[,option][,option][,...]``
2727    Configure user mode host network backend which requires no
2728    administrator privilege to run. Valid options are:
2730    ``id=id``
2731        Assign symbolic name for use in monitor commands.
2733    ``ipv4=on|off and ipv6=on|off``
2734        Specify that either IPv4 or IPv6 must be enabled. If neither is
2735        specified both protocols are enabled.
2737    ``net=addr[/mask]``
2738        Set IP network address the guest will see. Optionally specify
2739        the netmask, either in the form a.b.c.d or as number of valid
2740        top-most bits. Default is
2742    ``host=addr``
2743        Specify the guest-visible address of the host. Default is the
2744        2nd IP in the guest network, i.e. x.x.x.2.
2746    ``ipv6-net=addr[/int]``
2747        Set IPv6 network address the guest will see (default is
2748        fec0::/64). The network prefix is given in the usual hexadecimal
2749        IPv6 address notation. The prefix size is optional, and is given
2750        as the number of valid top-most bits (default is 64).
2752    ``ipv6-host=addr``
2753        Specify the guest-visible IPv6 address of the host. Default is
2754        the 2nd IPv6 in the guest network, i.e. xxxx::2.
2756    ``restrict=on|off``
2757        If this option is enabled, the guest will be isolated, i.e. it
2758        will not be able to contact the host and no guest IP packets
2759        will be routed over the host to the outside. This option does
2760        not affect any explicitly set forwarding rules.
2762    ``hostname=name``
2763        Specifies the client hostname reported by the built-in DHCP
2764        server.
2766    ``dhcpstart=addr``
2767        Specify the first of the 16 IPs the built-in DHCP server can
2768        assign. Default is the 15th to 31st IP in the guest network,
2769        i.e. x.x.x.15 to x.x.x.31.
2771    ``dns=addr``
2772        Specify the guest-visible address of the virtual nameserver. The
2773        address must be different from the host address. Default is the
2774        3rd IP in the guest network, i.e. x.x.x.3.
2776    ``ipv6-dns=addr``
2777        Specify the guest-visible address of the IPv6 virtual
2778        nameserver. The address must be different from the host address.
2779        Default is the 3rd IP in the guest network, i.e. xxxx::3.
2781    ``dnssearch=domain``
2782        Provides an entry for the domain-search list sent by the
2783        built-in DHCP server. More than one domain suffix can be
2784        transmitted by specifying this option multiple times. If
2785        supported, this will cause the guest to automatically try to
2786        append the given domain suffix(es) in case a domain name can not
2787        be resolved.
2789        Example:
2791        .. parsed-literal::
2793            |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
2795    ``domainname=domain``
2796        Specifies the client domain name reported by the built-in DHCP
2797        server.
2799    ``tftp=dir``
2800        When using the user mode network stack, activate a built-in TFTP
2801        server. The files in dir will be exposed as the root of a TFTP
2802        server. The TFTP client on the guest must be configured in
2803        binary mode (use the command ``bin`` of the Unix TFTP client).
2805    ``tftp-server-name=name``
2806        In BOOTP reply, broadcast name as the "TFTP server name"
2807        (RFC2132 option 66). This can be used to advise the guest to
2808        load boot files or configurations from a different server than
2809        the host address.
2811    ``bootfile=file``
2812        When using the user mode network stack, broadcast file as the
2813        BOOTP filename. In conjunction with ``tftp``, this can be used
2814        to network boot a guest from a local directory.
2816        Example (using pxelinux):
2818        .. parsed-literal::
2820            |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\
2821                -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
2823    ``smb=dir[,smbserver=addr]``
2824        When using the user mode network stack, activate a built-in SMB
2825        server so that Windows OSes can access to the host files in
2826        ``dir`` transparently. The IP address of the SMB server can be
2827        set to addr. By default the 4th IP in the guest network is used,
2828        i.e. x.x.x.4.
2830        In the guest Windows OS, the line:
2832        ::
2834   smbserver
2836        must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows
2837        9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows
2838        NT/2000).
2840        Then ``dir`` can be accessed in ``\\smbserver\qemu``.
2842        Note that a SAMBA server must be installed on the host OS.
2844    ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
2845        Redirect incoming TCP or UDP connections to the host port
2846        hostport to the guest IP address guestaddr on guest port
2847        guestport. If guestaddr is not specified, its value is x.x.x.15
2848        (default first address given by the built-in DHCP server). By
2849        specifying hostaddr, the rule can be bound to a specific host
2850        interface. If no connection type is set, TCP is used. This
2851        option can be given multiple times.
2853        For example, to redirect host X11 connection from screen 1 to
2854        guest screen 0, use the following:
2856        .. parsed-literal::
2858            # on the host
2859            |qemu_system| -nic user,hostfwd=tcp:
2860            # this host xterm should open in the guest X11 server
2861            xterm -display :1
2863        To redirect telnet connections from host port 5555 to telnet
2864        port on the guest, use the following:
2866        .. parsed-literal::
2868            # on the host
2869            |qemu_system| -nic user,hostfwd=tcp::5555-:23
2870            telnet localhost 5555
2872        Then when you use on the host ``telnet localhost 5555``, you
2873        connect to the guest telnet server.
2875    ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command``
2876        Forward guest TCP connections to the IP address server on port
2877        port to the character device dev or to a program executed by
2878        cmd:command which gets spawned for each connection. This option
2879        can be given multiple times.
2881        You can either use a chardev directly and have that one used
2882        throughout QEMU's lifetime, like in the following example:
2884        .. parsed-literal::
2886            # open on bootup, connect to it whenever
2887            # the guest accesses it
2888            |qemu_system| -nic user,guestfwd=tcp:
2890        Or you can execute a command on every TCP connection established
2891        by the guest, so that QEMU behaves similar to an inetd process
2892        for that virtual server:
2894        .. parsed-literal::
2896            # call "netcat 4321" on every TCP connection to
2897            # and connect the TCP stream to its stdin/stdout
2898            |qemu_system| -nic  'user,id=n1,guestfwd=tcp: 4321'
2900``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
2901    Configure a host TAP network backend with ID id.
2903    Use the network script file to configure it and the network script
2904    dfile to deconfigure it. If name is not provided, the OS
2905    automatically provides one. The default network configure script is
2906    ``/etc/qemu-ifup`` and the default network deconfigure script is
2907    ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
2908    disable script execution.
2910    If running QEMU as an unprivileged user, use the network helper
2911    to configure the TAP interface and attach it to the bridge.
2912    The default network helper executable is
2913    ``/path/to/qemu-bridge-helper`` and the default bridge device is
2914    ``br0``.
2916    ``fd``\ =h can be used to specify the handle of an already opened
2917    host TAP interface.
2919    Examples:
2921    .. parsed-literal::
2923        #launch a QEMU instance with the default network script
2924        |qemu_system| linux.img -nic tap
2926    .. parsed-literal::
2928        #launch a QEMU instance with two NICs, each one connected
2929        #to a TAP device
2930        |qemu_system| linux.img \\
2931                -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\
2932                -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
2934    .. parsed-literal::
2936        #launch a QEMU instance with the default network helper to
2937        #connect a TAP device to bridge br0
2938        |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
2939                -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
2941``-netdev bridge,id=id[,br=bridge][,helper=helper]``
2942    Connect a host TAP network interface to a host bridge device.
2944    Use the network helper helper to configure the TAP interface and
2945    attach it to the bridge. The default network helper executable is
2946    ``/path/to/qemu-bridge-helper`` and the default bridge device is
2947    ``br0``.
2949    Examples:
2951    .. parsed-literal::
2953        #launch a QEMU instance with the default network helper to
2954        #connect a TAP device to bridge br0
2955        |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
2957    .. parsed-literal::
2959        #launch a QEMU instance with the default network helper to
2960        #connect a TAP device to bridge qemubr0
2961        |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
2963``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
2964    This host network backend can be used to connect the guest's network
2965    to another QEMU virtual machine using a TCP socket connection. If
2966    ``listen`` is specified, QEMU waits for incoming connections on port
2967    (host is optional). ``connect`` is used to connect to another QEMU
2968    instance using the ``listen`` option. ``fd``\ =h specifies an
2969    already opened TCP socket.
2971    Example:
2973    .. parsed-literal::
2975        # launch a first QEMU instance
2976        |qemu_system| linux.img \\
2977                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
2978                         -netdev socket,id=n1,listen=:1234
2979        # connect the network of this instance to the network of the first instance
2980        |qemu_system| linux.img \\
2981                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
2982                         -netdev socket,id=n2,connect=
2984``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]``
2985    Configure a socket host network backend to share the guest's network
2986    traffic with another QEMU virtual machines using a UDP multicast
2987    socket, effectively making a bus for every QEMU with same multicast
2988    address maddr and port. NOTES:
2990    1. Several QEMU can be running on different hosts and share same bus
2991       (assuming correct multicast setup for these hosts).
2993    2. mcast support is compatible with User Mode Linux (argument
2994       ``ethN=mcast``), see http://user-mode-linux.sf.net.
2996    3. Use ``fd=h`` to specify an already opened UDP multicast socket.
2998    Example:
3000    .. parsed-literal::
3002        # launch one QEMU instance
3003        |qemu_system| linux.img \\
3004                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3005                         -netdev socket,id=n1,mcast=
3006        # launch another QEMU instance on same "bus"
3007        |qemu_system| linux.img \\
3008                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
3009                         -netdev socket,id=n2,mcast=
3010        # launch yet another QEMU instance on same "bus"
3011        |qemu_system| linux.img \\
3012                         -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\
3013                         -netdev socket,id=n3,mcast=
3015    Example (User Mode Linux compat.):
3017    .. parsed-literal::
3019        # launch QEMU instance (note mcast address selected is UML's default)
3020        |qemu_system| linux.img \\
3021                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3022                         -netdev socket,id=n1,mcast=
3023        # launch UML
3024        /path/to/linux ubd0=/path/to/root_fs eth0=mcast
3026    Example (send packets from host's
3028    .. parsed-literal::
3030        |qemu_system| linux.img \\
3031                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3032                         -netdev socket,id=n1,mcast=,localaddr=
3034``-netdev l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6=on|off][,udp=on|off][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]``
3035    Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
3036    is a popular protocol to transport Ethernet (and other Layer 2) data
3037    frames between two systems. It is present in routers, firewalls and
3038    the Linux kernel (from version 3.3 onwards).
3040    This transport allows a VM to communicate to another VM, router or
3041    firewall directly.
3043    ``src=srcaddr``
3044        source address (mandatory)
3046    ``dst=dstaddr``
3047        destination address (mandatory)
3049    ``udp``
3050        select udp encapsulation (default is ip).
3052    ``srcport=srcport``
3053        source udp port.
3055    ``dstport=dstport``
3056        destination udp port.
3058    ``ipv6``
3059        force v6, otherwise defaults to v4.
3061    ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
3062        Cookies are a weak form of security in the l2tpv3 specification.
3063        Their function is mostly to prevent misconfiguration. By default
3064        they are 32 bit.
3066    ``cookie64``
3067        Set cookie size to 64 bit instead of the default 32
3069    ``counter=off``
3070        Force a 'cut-down' L2TPv3 with no counter as in
3071        draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
3073    ``pincounter=on``
3074        Work around broken counter handling in peer. This may also help
3075        on networks which have packet reorder.
3077    ``offset=offset``
3078        Add an extra offset between header and data
3080    For example, to attach a VM running on host via L2TPv3 to
3081    the bridge br-lan on the remote Linux host
3083    .. parsed-literal::
3085        # Setup tunnel on linux host using raw ip as encapsulation
3086        # on
3087        ip l2tp add tunnel remote local tunnel_id 1 peer_tunnel_id 1 \\
3088            encap udp udp_sport 16384 udp_dport 16384
3089        ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\
3090            0xFFFFFFFF peer_session_id 0xFFFFFFFF
3091        ifconfig vmtunnel0 mtu 1500
3092        ifconfig vmtunnel0 up
3093        brctl addif br-lan vmtunnel0
3096        # on
3097        # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
3099        |qemu_system| linux.img -device e1000,netdev=n1 \\
3100            -netdev l2tpv3,id=n1,src=,dst=,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
3102``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
3103    Configure VDE backend to connect to PORT n of a vde switch running
3104    on host and listening for incoming connections on socketpath. Use
3105    GROUP groupname and MODE octalmode to change default ownership and
3106    permissions for communication port. This option is only available if
3107    QEMU has been compiled with vde support enabled.
3109    Example:
3111    .. parsed-literal::
3113        # launch vde switch
3114        vde_switch -F -sock /tmp/myswitch
3115        # launch QEMU instance
3116        |qemu_system| linux.img -nic vde,sock=/tmp/myswitch
3118``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
3119    Establish a vhost-user netdev, backed by a chardev id. The chardev
3120    should be a unix domain socket backed one. The vhost-user uses a
3121    specifically defined protocol to pass vhost ioctl replacement
3122    messages to an application on the other end of the socket. On
3123    non-MSIX guests, the feature can be forced with vhostforce. Use
3124    'queues=n' to specify the number of queues to be created for
3125    multiqueue vhost-user.
3127    Example:
3129    ::
3131        qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
3132             -numa node,memdev=mem \
3133             -chardev socket,id=chr0,path=/path/to/socket \
3134             -netdev type=vhost-user,id=net0,chardev=chr0 \
3135             -device virtio-net-pci,netdev=net0
3137``-netdev vhost-vdpa,vhostdev=/path/to/dev``
3138    Establish a vhost-vdpa netdev.
3140    vDPA device is a device that uses a datapath which complies with
3141    the virtio specifications with a vendor specific control path.
3142    vDPA devices can be both physically located on the hardware or
3143    emulated by software.
3145``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
3146    Create a hub port on the emulated hub with ID hubid.
3148    The hubport netdev lets you connect a NIC to a QEMU emulated hub
3149    instead of a single netdev. Alternatively, you can also connect the
3150    hubport to another netdev with ID nd by using the ``netdev=nd``
3151    option.
3153``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
3154    Legacy option to configure or create an on-board (or machine
3155    default) Network Interface Card(NIC) and connect it either to the
3156    emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
3157    If model is omitted, then the default NIC model associated with the
3158    machine type is used. Note that the default NIC model may change in
3159    future QEMU releases, so it is highly recommended to always specify
3160    a model. Optionally, the MAC address can be changed to mac, the
3161    device address set to addr (PCI cards only), and a name can be
3162    assigned for use in monitor commands. Optionally, for PCI cards, you
3163    can specify the number v of MSI-X vectors that the card should have;
3164    this option currently only affects virtio cards; set v = 0 to
3165    disable MSI-X. If no ``-net`` option is specified, a single NIC is
3166    created. QEMU can emulate several different models of network card.
3167    Use ``-net nic,model=help`` for a list of available devices for your
3168    target.
3170``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
3171    Configure a host network backend (with the options corresponding to
3172    the same ``-netdev`` option) and connect it to the emulated hub 0
3173    (the default hub). Use name to specify the name of the hub port.
3178DEFHEADING(Character device options:)
3180DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
3181    "-chardev help\n"
3182    "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3183    "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off][,reconnect=seconds]\n"
3184    "         [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n"
3185    "         [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
3186    "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n"
3187    "         [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n"
3188    "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
3189    "         [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n"
3190    "         [,logfile=PATH][,logappend=on|off]\n"
3191    "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3192    "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
3193    "         [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3194    "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
3195    "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3196    "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3197#ifdef _WIN32
3198    "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3199    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3201    "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3202    "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
3204#ifdef CONFIG_BRLAPI
3205    "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3207#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
3208        || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
3209    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3210    "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3212#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
3213    "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3214    "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3216#if defined(CONFIG_SPICE)
3217    "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3218    "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3220    , QEMU_ARCH_ALL
3224The general form of a character device option is:
3226``-chardev backend,id=id[,mux=on|off][,options]``
3227    Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
3228    ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
3229    ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``,
3230    ``spicevmc``, ``spiceport``. The specific backend will determine the
3231    applicable options.
3233    Use ``-chardev help`` to print all available chardev backend types.
3235    All devices must have an id, which can be any string up to 127
3236    characters long. It is used to uniquely identify this device in
3237    other command line directives.
3239    A character device may be used in multiplexing mode by multiple
3240    front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
3241    a "1:N" device, and here the "1" end is your specified chardev
3242    backend, and the "N" end is the various parts of QEMU that can talk
3243    to a chardev. If you create a chardev with ``id=myid`` and
3244    ``mux=on``, QEMU will create a multiplexer with your specified ID,
3245    and you can then configure multiple front ends to use that chardev
3246    ID for their input/output. Up to four different front ends can be
3247    connected to a single multiplexed chardev. (Without multiplexing
3248    enabled, a chardev can only be used by a single front end.) For
3249    instance you could use this to allow a single stdio chardev to be
3250    used by two serial ports and the QEMU monitor:
3252    ::
3254        -chardev stdio,mux=on,id=char0 \
3255        -mon chardev=char0,mode=readline \
3256        -serial chardev:char0 \
3257        -serial chardev:char0
3259    You can have more than one multiplexer in a system configuration;
3260    for instance you could have a TCP port multiplexed between UART 0
3261    and UART 1, and stdio multiplexed between the QEMU monitor and a
3262    parallel port:
3264    ::
3266        -chardev stdio,mux=on,id=char0 \
3267        -mon chardev=char0,mode=readline \
3268        -parallel chardev:char0 \
3269        -chardev tcp,...,mux=on,id=char1 \
3270        -serial chardev:char1 \
3271        -serial chardev:char1
3273    When you're using a multiplexed character device, some escape
3274    sequences are interpreted in the input. See the chapter about
3275    :ref:`keys in the character backend multiplexer` in the
3276    System Emulation Users Guide for more details.
3278    Note that some other command line options may implicitly create
3279    multiplexed character backends; for instance ``-serial mon:stdio``
3280    creates a multiplexed stdio backend connected to the serial port and
3281    the QEMU monitor, and ``-nographic`` also multiplexes the console
3282    and the monitor to stdio.
3284    There is currently no support for multiplexing in the other
3285    direction (where a single QEMU front end takes input and output from
3286    multiple chardevs).
3288    Every backend supports the ``logfile`` option, which supplies the
3289    path to a file to record all data transmitted via the backend. The
3290    ``logappend`` option controls whether the log file will be truncated
3291    or appended to when opened.
3293The available backends are:
3295``-chardev null,id=id``
3296    A void device. This device will not emit any data, and will drop any
3297    data it receives. The null backend does not take any options.
3299``-chardev socket,id=id[,TCP options or unix options][,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,tls-creds=id][,tls-authz=id]``
3300    Create a two-way stream socket, which can be either a TCP or a unix
3301    socket. A unix socket will be created if ``path`` is specified.
3302    Behaviour is undefined if TCP options are specified for a unix
3303    socket.
3305    ``server=on|off`` specifies that the socket shall be a listening socket.
3307    ``wait=on|off`` specifies that QEMU should not block waiting for a client
3308    to connect to a listening socket.
3310    ``telnet=on|off`` specifies that traffic on the socket should interpret
3311    telnet escape sequences.
3313    ``websocket=on|off`` specifies that the socket uses WebSocket protocol for
3314    communication.
3316    ``reconnect`` sets the timeout for reconnecting on non-server
3317    sockets when the remote end goes away. qemu will delay this many
3318    seconds and then attempt to reconnect. Zero disables reconnecting,
3319    and is the default.
3321    ``tls-creds`` requests enablement of the TLS protocol for
3322    encryption, and specifies the id of the TLS credentials to use for
3323    the handshake. The credentials must be previously created with the
3324    ``-object tls-creds`` argument.
3326    ``tls-auth`` provides the ID of the QAuthZ authorization object
3327    against which the client's x509 distinguished name will be
3328    validated. This object is only resolved at time of use, so can be
3329    deleted and recreated on the fly while the chardev server is active.
3330    If missing, it will default to denying access.
3332    TCP and unix socket options are given below:
3334    ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]``
3335        ``host`` for a listening socket specifies the local address to
3336        be bound. For a connecting socket species the remote host to
3337        connect to. ``host`` is optional for listening sockets. If not
3338        specified it defaults to ````.
3340        ``port`` for a listening socket specifies the local port to be
3341        bound. For a connecting socket specifies the port on the remote
3342        host to connect to. ``port`` can be given as either a port
3343        number or a service name. ``port`` is required.
3345        ``to`` is only relevant to listening sockets. If it is
3346        specified, and ``port`` cannot be bound, QEMU will attempt to
3347        bind to subsequent ports up to and including ``to`` until it
3348        succeeds. ``to`` must be specified as a port number.
3350        ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4
3351        or IPv6 must be used. If neither is specified the socket may
3352        use either protocol.
3354        ``nodelay=on|off`` disables the Nagle algorithm.
3356    ``unix options: path=path[,abstract=on|off][,tight=on|off]``
3357        ``path`` specifies the local path of the unix socket. ``path``
3358        is required.
3359        ``abstract=on|off`` specifies the use of the abstract socket namespace,
3360        rather than the filesystem.  Optional, defaults to false.
3361        ``tight=on|off`` sets the socket length of abstract sockets to their minimum,
3362        rather than the full sun_path length.  Optional, defaults to true.
3364``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]``
3365    Sends all traffic from the guest to a remote host over UDP.
3367    ``host`` specifies the remote host to connect to. If not specified
3368    it defaults to ``localhost``.
3370    ``port`` specifies the port on the remote host to connect to.
3371    ``port`` is required.
3373    ``localaddr`` specifies the local address to bind to. If not
3374    specified it defaults to ````.
3376    ``localport`` specifies the local port to bind to. If not specified
3377    any available local port will be used.
3379    ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used.
3380    If neither is specified the device may use either protocol.
3382``-chardev msmouse,id=id``
3383    Forward QEMU's emulated msmouse events to the guest. ``msmouse``
3384    does not take any options.
3386``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
3387    Connect to a QEMU text console. ``vc`` may optionally be given a
3388    specific size.
3390    ``width`` and ``height`` specify the width and height respectively
3391    of the console, in pixels.
3393    ``cols`` and ``rows`` specify that the console be sized to fit a
3394    text console with the given dimensions.
3396``-chardev ringbuf,id=id[,size=size]``
3397    Create a ring buffer with fixed size ``size``. size must be a power
3398    of two and defaults to ``64K``.
3400``-chardev file,id=id,path=path``
3401    Log all traffic received from the guest to a file.
3403    ``path`` specifies the path of the file to be opened. This file will
3404    be created if it does not already exist, and overwritten if it does.
3405    ``path`` is required.
3407``-chardev pipe,id=id,path=path``
3408    Create a two-way connection to the guest. The behaviour differs
3409    slightly between Windows hosts and other hosts:
3411    On Windows, a single duplex pipe will be created at
3412    ``\\.pipe\path``.
3414    On other hosts, 2 pipes will be created called ``path.in`` and
3415    ``path.out``. Data written to ``path.in`` will be received by the
3416    guest. Data written by the guest can be read from ``path.out``. QEMU
3417    will not create these fifos, and requires them to be present.
3419    ``path`` forms part of the pipe path as described above. ``path`` is
3420    required.
3422``-chardev console,id=id``
3423    Send traffic from the guest to QEMU's standard output. ``console``
3424    does not take any options.
3426    ``console`` is only available on Windows hosts.
3428``-chardev serial,id=id,path=path``
3429    Send traffic from the guest to a serial device on the host.
3431    On Unix hosts serial will actually accept any tty device, not only
3432    serial lines.
3434    ``path`` specifies the name of the serial device to open.
3436``-chardev pty,id=id``
3437    Create a new pseudo-terminal on the host and connect to it. ``pty``
3438    does not take any options.
3440    ``pty`` is not available on Windows hosts.
3442``-chardev stdio,id=id[,signal=on|off]``
3443    Connect to standard input and standard output of the QEMU process.
3445    ``signal`` controls if signals are enabled on the terminal, that
3446    includes exiting QEMU with the key sequence Control-c. This option
3447    is enabled by default, use ``signal=off`` to disable it.
3449``-chardev braille,id=id``
3450    Connect to a local BrlAPI server. ``braille`` does not take any
3451    options.
3453``-chardev tty,id=id,path=path``
3454    ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD
3455    and DragonFlyBSD hosts. It is an alias for ``serial``.
3457    ``path`` specifies the path to the tty. ``path`` is required.
3459``-chardev parallel,id=id,path=path``
3460  \
3461``-chardev parport,id=id,path=path``
3462    ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
3463    hosts.
3465    Connect to a local parallel port.
3467    ``path`` specifies the path to the parallel port device. ``path`` is
3468    required.
3470``-chardev spicevmc,id=id,debug=debug,name=name``
3471    ``spicevmc`` is only available when spice support is built in.
3473    ``debug`` debug level for spicevmc
3475    ``name`` name of spice channel to connect to
3477    Connect to a spice virtual machine channel, such as vdiport.
3479``-chardev spiceport,id=id,debug=debug,name=name``
3480    ``spiceport`` is only available when spice support is built in.
3482    ``debug`` debug level for spicevmc
3484    ``name`` name of spice port to connect to
3486    Connect to a spice port, allowing a Spice client to handle the
3487    traffic identified by a name (preferably a fqdn).
3492#ifdef CONFIG_TPM
3493DEFHEADING(TPM device options:)
3495DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3496    "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3497    "                use path to provide path to a character device; default is /dev/tpm0\n"
3498    "                use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
3499    "                not provided it will be searched for in /sys/class/misc/tpm?/device\n"
3500    "-tpmdev emulator,id=id,chardev=dev\n"
3501    "                configure the TPM device using chardev backend\n",
3502    QEMU_ARCH_ALL)
3504The general form of a TPM device option is:
3506``-tpmdev backend,id=id[,options]``
3507    The specific backend type will determine the applicable options. The
3508    ``-tpmdev`` option creates the TPM backend and requires a
3509    ``-device`` option that specifies the TPM frontend interface model.
3511    Use ``-tpmdev help`` to print all available TPM backend types.
3513The available backends are:
3515``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
3516    (Linux-host only) Enable access to the host's TPM using the
3517    passthrough driver.
3519    ``path`` specifies the path to the host's TPM device, i.e., on a
3520    Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
3521    default ``/dev/tpm0`` is used.
3523    ``cancel-path`` specifies the path to the host TPM device's sysfs
3524    entry allowing for cancellation of an ongoing TPM command.
3525    ``cancel-path`` is optional and by default QEMU will search for the
3526    sysfs entry to use.
3528    Some notes about using the host's TPM with the passthrough driver:
3530    The TPM device accessed by the passthrough driver must not be used
3531    by any other application on the host.
3533    Since the host's firmware (BIOS/UEFI) has already initialized the
3534    TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
3535    the TPM again and may therefore not show a TPM-specific menu that
3536    would otherwise allow the user to configure the TPM, e.g., allow the
3537    user to enable/disable or activate/deactivate the TPM. Further, if
3538    TPM ownership is released from within a VM then the host's TPM will
3539    get disabled and deactivated. To enable and activate the TPM again
3540    afterwards, the host has to be rebooted and the user is required to
3541    enter the firmware's menu to enable and activate the TPM. If the TPM
3542    is left disabled and/or deactivated most TPM commands will fail.
3544    To create a passthrough TPM use the following two options:
3546    ::
3548        -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3550    Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
3551    ``tpmdev=tpm0`` in the device option.
3553``-tpmdev emulator,id=id,chardev=dev``
3554    (Linux-host only) Enable access to a TPM emulator using Unix domain
3555    socket based chardev backend.
3557    ``chardev`` specifies the unique ID of a character device backend
3558    that provides connection to the software TPM server.
3560    To create a TPM emulator backend device with chardev socket backend:
3562    ::
3564        -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3571DEFHEADING(Linux/Multiboot boot specific:)
3573When using these options, you can use a given Linux or Multiboot kernel
3574without installing it in the disk image. It can be useful for easier
3575testing of various kernels.
3580DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
3581    "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
3583``-kernel bzImage``
3584    Use bzImage as kernel image. The kernel can be either a Linux kernel
3585    or in multiboot format.
3588DEF("append", HAS_ARG, QEMU_OPTION_append, \
3589    "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
3591``-append cmdline``
3592    Use cmdline as kernel command line
3595DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
3596           "-initrd file    use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
3598``-initrd file``
3599    Use file as initial ram disk.
3601``-initrd "file1 arg=foo,file2"``
3602    This syntax is only available with multiboot.
3604    Use file1 and file2 as modules and pass arg=foo as parameter to the
3605    first module.
3608DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
3609    "-dtb    file    use 'file' as device tree image\n", QEMU_ARCH_ALL)
3611``-dtb file``
3612    Use file as a device tree binary (dtb) image and pass it to the
3613    kernel on boot.
3618DEFHEADING(Debug/Expert options:)
3620DEF("compat", HAS_ARG, QEMU_OPTION_compat,
3621    "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n"
3622    "                Policy for handling deprecated management interfaces\n",
3623    QEMU_ARCH_ALL)
3625``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]``
3626    Set policy for handling deprecated management interfaces (experimental):
3628    ``deprecated-input=accept`` (default)
3629        Accept deprecated commands and arguments
3630    ``deprecated-input=reject``
3631        Reject deprecated commands and arguments
3632    ``deprecated-input=crash``
3633        Crash on deprecated commands and arguments
3634    ``deprecated-output=accept`` (default)
3635        Emit deprecated command results and events
3636    ``deprecated-output=hide``
3637        Suppress deprecated command results and events
3639    Limitation: covers only syntactic aspects of QMP.
3642DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
3643    "-fw_cfg [name=]<name>,file=<file>\n"
3644    "                add named fw_cfg entry with contents from file\n"
3645    "-fw_cfg [name=]<name>,string=<str>\n"
3646    "                add named fw_cfg entry with contents from string\n",
3647    QEMU_ARCH_ALL)
3649``-fw_cfg [name=]name,file=file``
3650    Add named fw\_cfg entry with contents from file file.
3652``-fw_cfg [name=]name,string=str``
3653    Add named fw\_cfg entry with contents from string str.
3655    The terminating NUL character of the contents of str will not be
3656    included as part of the fw\_cfg item data. To insert contents with
3657    embedded NUL characters, you have to use the file parameter.
3659    The fw\_cfg entries are passed by QEMU through to the guest.
3661    Example:
3663    ::
3665            -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
3667    creates an fw\_cfg entry named opt/com.mycompany/blob with contents
3668    from ./my\_blob.bin.
3671DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
3672    "-serial dev     redirect the serial port to char device 'dev'\n",
3673    QEMU_ARCH_ALL)
3675``-serial dev``
3676    Redirect the virtual serial port to host character device dev. The
3677    default device is ``vc`` in graphical mode and ``stdio`` in non
3678    graphical mode.
3680    This option can be used several times to simulate up to 4 serial
3681    ports.
3683    Use ``-serial none`` to disable all serial ports.
3685    Available character devices are:
3687    ``vc[:WxH]``
3688        Virtual console. Optionally, a width and height can be given in
3689        pixel with
3691        ::
3693            vc:800x600
3695        It is also possible to specify width or height in characters:
3697        ::
3699            vc:80Cx24C
3701    ``pty``
3702        [Linux only] Pseudo TTY (a new PTY is automatically allocated)
3704    ``none``
3705        No device is allocated.
3707    ``null``
3708        void device
3710    ``chardev:id``
3711        Use a named character device defined with the ``-chardev``
3712        option.
3714    ``/dev/XXX``
3715        [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
3716        port parameters are set according to the emulated ones.
3718    ``/dev/parportN``
3719        [Linux only, parallel port only] Use host parallel port N.
3720        Currently SPP and EPP parallel port features can be used.
3722    ``file:filename``
3723        Write output to filename. No character can be read.
3725    ``stdio``
3726        [Unix only] standard input/output
3728    ``pipe:filename``
3729        name pipe filename
3731    ``COMn``
3732        [Windows only] Use host serial port n
3734    ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
3735        This implements UDP Net Console. When remote\_host or src\_ip
3736        are not specified they default to ````. When not using a
3737        specified src\_port a random port is automatically chosen.
3739        If you just want a simple readonly console you can use
3740        ``netcat`` or ``nc``, by starting QEMU with:
3741        ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
3742        QEMU writes something to that port it will appear in the
3743        netconsole session.
3745        If you plan to send characters back via netconsole or you want
3746        to stop and start QEMU a lot of times, you should have QEMU use
3747        the same source port each time by using something like ``-serial
3748        udp::4555@:4556`` to QEMU. Another approach is to use a patched
3749        version of netcat which can listen to a TCP port and send and
3750        receive characters via udp. If you have a patched version of
3751        netcat which activates telnet remote echo and single char
3752        transfer, then you can use the following options to set up a
3753        netcat redirector to allow telnet on port 5555 to access the
3754        QEMU port.
3756        ``QEMU Options:``
3757            -serial udp::4555@:4556
3759        ``netcat options:``
3760            -u -P 4555 -L -t -p 5555 -I -T
3762        ``telnet options:``
3763            localhost 5555
3765    ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]``
3766        The TCP Net Console has two modes of operation. It can send the
3767        serial I/O to a location or wait for a connection from a
3768        location. By default the TCP Net Console is sent to host at the
3769        port. If you use the ``server=on`` option QEMU will wait for a client
3770        socket application to connect to the port before continuing,
3771        unless the ``wait=on|off`` option was specified. The ``nodelay=on|off``
3772        option disables the Nagle buffering algorithm. The ``reconnect=on``
3773        option only applies if ``server=no`` is set, if the connection goes
3774        down it will attempt to reconnect at the given interval. If host
3775        is omitted, is assumed. Only one TCP connection at a
3776        time is accepted. You can use ``telnet=on`` to connect to the
3777        corresponding character device.
3779        ``Example to send tcp console to port 4444``
3780            -serial tcp:
3782        ``Example to listen and wait on port 4444 for connection``
3783            -serial tcp::4444,server=on
3785        ``Example to not wait and listen on ip port 4444``
3786            -serial tcp:,server=on,wait=off
3788    ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]``
3789        The telnet protocol is used instead of raw tcp sockets. The
3790        options work the same as if you had specified ``-serial tcp``.
3791        The difference is that the port acts like a telnet server or
3792        client using telnet option negotiation. This will also allow you
3793        to send the MAGIC\_SYSRQ sequence if you use a telnet that
3794        supports sending the break sequence. Typically in unix telnet
3795        you do it with Control-] and then type "send break" followed by
3796        pressing the enter key.
3798    ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]``
3799        The WebSocket protocol is used instead of raw tcp socket. The
3800        port acts as a WebSocket server. Client mode is not supported.
3802    ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]``
3803        A unix domain socket is used instead of a tcp socket. The option
3804        works the same as if you had specified ``-serial tcp`` except
3805        the unix domain socket path is used for connections.
3807    ``mon:dev_string``
3808        This is a special option to allow the monitor to be multiplexed
3809        onto another serial port. The monitor is accessed with key
3810        sequence of Control-a and then pressing c. dev\_string should be
3811        any one of the serial devices specified above. An example to
3812        multiplex the monitor onto a telnet server listening on port
3813        4444 would be:
3815        ``-serial mon:telnet::4444,server=on,wait=off``
3817        When the monitor is multiplexed to stdio in this way, Ctrl+C
3818        will not terminate QEMU any more but will be passed to the guest
3819        instead.
3821    ``braille``
3822        Braille device. This will use BrlAPI to display the braille
3823        output on a real or fake device.
3825    ``msmouse``
3826        Three button serial mouse. Configure the guest to use Microsoft
3827        protocol.
3830DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
3831    "-parallel dev   redirect the parallel port to char device 'dev'\n",
3832    QEMU_ARCH_ALL)
3834``-parallel dev``
3835    Redirect the virtual parallel port to host device dev (same devices
3836    as the serial port). On Linux hosts, ``/dev/parportN`` can be used
3837    to use hardware devices connected on the corresponding host parallel
3838    port.
3840    This option can be used several times to simulate up to 3 parallel
3841    ports.
3843    Use ``-parallel none`` to disable all parallel ports.
3846DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
3847    "-monitor dev    redirect the monitor to char device 'dev'\n",
3848    QEMU_ARCH_ALL)
3850``-monitor dev``
3851    Redirect the monitor to host device dev (same devices as the serial
3852    port). The default device is ``vc`` in graphical mode and ``stdio``
3853    in non graphical mode. Use ``-monitor none`` to disable the default
3854    monitor.
3856DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
3857    "-qmp dev        like -monitor but opens in 'control' mode\n",
3858    QEMU_ARCH_ALL)
3860``-qmp dev``
3861    Like -monitor but opens in 'control' mode.
3863DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
3864    "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
3865    QEMU_ARCH_ALL)
3867``-qmp-pretty dev``
3868    Like -qmp but uses pretty JSON formatting.
3871DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
3872    "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
3874``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
3875    Setup monitor on chardev name. ``mode=control`` configures 
3876    a QMP monitor (a JSON RPC-style protocol) and it is not the
3877    same as HMP, the human monitor that has a "(qemu)" prompt.
3878    ``pretty`` is only valid when ``mode=control``, 
3879    turning on JSON pretty printing to ease
3880    human reading and debugging.
3883DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
3884    "-debugcon dev   redirect the debug console to char device 'dev'\n",
3885    QEMU_ARCH_ALL)
3887``-debugcon dev``
3888    Redirect the debug console to host device dev (same devices as the
3889    serial port). The debug console is an I/O port which is typically
3890    port 0xe9; writing to that I/O port sends output to this device. The
3891    default device is ``vc`` in graphical mode and ``stdio`` in non
3892    graphical mode.
3895DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
3896    "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
3898``-pidfile file``
3899    Store the QEMU process PID in file. It is useful if you launch QEMU
3900    from a script.
3903DEF("singlestep", 0, QEMU_OPTION_singlestep, \
3904    "-singlestep     always run in singlestep mode\n", QEMU_ARCH_ALL)
3907    Run the emulation in single step mode.
3910DEF("preconfig", 0, QEMU_OPTION_preconfig, \
3911    "--preconfig     pause QEMU before machine is initialized (experimental)\n",
3912    QEMU_ARCH_ALL)
3915    Pause QEMU for interactive configuration before the machine is
3916    created, which allows querying and configuring properties that will
3917    affect machine initialization. Use QMP command 'x-exit-preconfig' to
3918    exit the preconfig state and move to the next state (i.e. run guest
3919    if -S isn't used or pause the second time if -S is used). This
3920    option is experimental.
3923DEF("S", 0, QEMU_OPTION_S, \
3924    "-S              freeze CPU at startup (use 'c' to start execution)\n",
3925    QEMU_ARCH_ALL)
3928    Do not start CPU at startup (you must type 'c' in the monitor).
3931DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
3932    "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
3933    "                run qemu with overcommit hints\n"
3934    "                mem-lock=on|off controls memory lock support (default: off)\n"
3935    "                cpu-pm=on|off controls cpu power management (default: off)\n",
3936    QEMU_ARCH_ALL)
3938``-overcommit mem-lock=on|off``
3939  \ 
3940``-overcommit cpu-pm=on|off``
3941    Run qemu with hints about host resource overcommit. The default is
3942    to assume that host overcommits all resources.
3944    Locking qemu and guest memory can be enabled via ``mem-lock=on``
3945    (disabled by default). This works when host memory is not
3946    overcommitted and reduces the worst-case latency for guest.
3948    Guest ability to manage power state of host cpus (increasing latency
3949    for other processes on the same host cpu, but decreasing latency for
3950    guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
3951    works best when host CPU is not overcommitted. When used, host
3952    estimates of CPU cycle and power utilization will be incorrect, not
3953    taking into account guest idle time.
3956DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
3957    "-gdb dev        accept gdb connection on 'dev'. (QEMU defaults to starting\n"
3958    "                the guest without waiting for gdb to connect; use -S too\n"
3959    "                if you want it to not start execution.)\n",
3960    QEMU_ARCH_ALL)
3962``-gdb dev``
3963    Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter
3964    in the System Emulation Users Guide). Note that this option does not pause QEMU
3965    execution -- if you want QEMU to not start the guest until you
3966    connect with gdb and issue a ``continue`` command, you will need to
3967    also pass the ``-S`` option to QEMU.
3969    The most usual configuration is to listen on a local TCP socket::
3971        -gdb tcp::3117
3973    but you can specify other backends; UDP, pseudo TTY, or even stdio
3974    are all reasonable use cases. For example, a stdio connection
3975    allows you to start QEMU from within gdb and establish the
3976    connection via a pipe:
3978    .. parsed-literal::
3980        (gdb) target remote | exec |qemu_system| -gdb stdio ...
3983DEF("s", 0, QEMU_OPTION_s, \
3984    "-s              shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
3985    QEMU_ARCH_ALL)
3988    Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
3989    (see the :ref:`GDB usage` chapter in the System Emulation Users Guide).
3992DEF("d", HAS_ARG, QEMU_OPTION_d, \
3993    "-d item1,...    enable logging of specified items (use '-d help' for a list of log items)\n",
3994    QEMU_ARCH_ALL)
3996``-d item1[,...]``
3997    Enable logging of specified items. Use '-d help' for a list of log
3998    items.
4002    "-D logfile      output log to logfile (default stderr)\n",
4003    QEMU_ARCH_ALL)
4005``-D logfile``
4006    Output log in logfile instead of to stderr
4010    "-dfilter range,..  filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
4011    QEMU_ARCH_ALL)
4013``-dfilter range1[,...]``
4014    Filter debug output to that relevant to a range of target addresses.
4015    The filter spec can be either start+size, start-size or start..end
4016    where start end and size are the addresses and sizes required. For
4017    example:
4019    ::
4021            -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
4023    Will dump output for any code in the 0x1000 sized block starting at
4024    0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
4025    another 0x1000 sized block starting at 0xffffffc00005f000.
4028DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
4029    "-seed number       seed the pseudo-random number generator\n",
4030    QEMU_ARCH_ALL)
4032``-seed number``
4033    Force the guest to use a deterministic pseudo-random number
4034    generator, seeded with number. This does not affect crypto routines
4035    within the host.
4039    "-L path         set the directory for the BIOS, VGA BIOS and keymaps\n",
4040    QEMU_ARCH_ALL)
4042``-L  path``
4043    Set the directory for the BIOS, VGA BIOS and keymaps.
4045    To list all the data directories, use ``-L help``.
4048DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
4049    "-bios file      set the filename for the BIOS\n", QEMU_ARCH_ALL)
4051``-bios file``
4052    Set the filename for the BIOS.
4055DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
4056    "-enable-kvm     enable KVM full virtualization support\n", QEMU_ARCH_ALL)
4059    Enable KVM full virtualization support. This option is only
4060    available if KVM support is enabled when compiling.
4063DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
4064    "-xen-domid id   specify xen guest domain id\n", QEMU_ARCH_ALL)
4065DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
4066    "-xen-attach     attach to existing xen domain\n"
4067    "                libxl will use this when starting QEMU\n",
4068    QEMU_ARCH_ALL)
4069DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
4070    "-xen-domid-restrict     restrict set of available xen operations\n"
4071    "                        to specified domain id. (Does not affect\n"
4072    "                        xenpv machine type).\n",
4073    QEMU_ARCH_ALL)
4075``-xen-domid id``
4076    Specify xen guest domain id (XEN only).
4079    Attach to existing xen domain. libxl will use this when starting
4080    QEMU (XEN only). Restrict set of available xen operations to
4081    specified domain id (XEN only).
4084DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
4085    "-no-reboot      exit instead of rebooting\n", QEMU_ARCH_ALL)
4088    Exit instead of rebooting.
4091DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
4092    "-no-shutdown    stop before shutdown\n", QEMU_ARCH_ALL)
4095    Don't exit QEMU on guest shutdown, but instead only stop the
4096    emulation. This allows for instance switching to monitor to commit
4097    changes to the disk image.
4100DEF("action", HAS_ARG, QEMU_OPTION_action,
4101    "-action reboot=reset|shutdown\n"
4102    "                   action when guest reboots [default=reset]\n"
4103    "-action shutdown=poweroff|pause\n"
4104    "                   action when guest shuts down [default=poweroff]\n"
4105    "-action panic=pause|shutdown|none\n"
4106    "                   action when guest panics [default=shutdown]\n"
4107    "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
4108    "                   action when watchdog fires [default=reset]\n",
4109    QEMU_ARCH_ALL)
4111``-action event=action``
4112    The action parameter serves to modify QEMU's default behavior when
4113    certain guest events occur. It provides a generic method for specifying the
4114    same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown``
4115    parameters.
4117    Examples:
4119    ``-action panic=none``
4120    ``-action reboot=shutdown,shutdown=pause``
4121    ``-watchdog i6300esb -action watchdog=pause``
4125DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
4126    "-loadvm [tag|id]\n" \
4127    "                start right away with a saved state (loadvm in monitor)\n",
4128    QEMU_ARCH_ALL)
4130``-loadvm file``
4131    Start right away with a saved state (``loadvm`` in monitor)
4134#ifndef _WIN32
4135DEF("daemonize", 0, QEMU_OPTION_daemonize, \
4136    "-daemonize      daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
4140    Daemonize the QEMU process after initialization. QEMU will not
4141    detach from standard IO until it is ready to receive connections on
4142    any of its devices. This option is a useful way for external
4143    programs to launch QEMU without having to cope with initialization
4144    race conditions.
4147DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
4148    "-option-rom rom load a file, rom, into the option ROM space\n",
4149    QEMU_ARCH_ALL)
4151``-option-rom file``
4152    Load the contents of file as an option ROM. This option is useful to
4153    load things like EtherBoot.
4156DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
4157    "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
4158    "                set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
4159    QEMU_ARCH_ALL)
4162``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
4163    Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
4164    the current UTC or local time, respectively. ``localtime`` is
4165    required for correct date in MS-DOS or Windows. To start at a
4166    specific point in time, provide datetime in the format
4167    ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.
4169    By default the RTC is driven by the host system time. This allows
4170    using of the RTC as accurate reference clock inside the guest,
4171    specifically if the host time is smoothly following an accurate
4172    external reference clock, e.g. via NTP. If you want to isolate the
4173    guest time from the host, you can set ``clock`` to ``rt`` instead,
4174    which provides a host monotonic clock if host support it. To even
4175    prevent the RTC from progressing during suspension, you can set
4176    ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
4177    recommended especially in icount mode in order to preserve
4178    determinism; however, note that in icount mode the speed of the
4179    virtual clock is variable and can in general differ from the host
4180    clock.
4182    Enable ``driftfix`` (i386 targets only) if you experience time drift
4183    problems, specifically with Windows' ACPI HAL. This option will try
4184    to figure out how many timer interrupts were not processed by the
4185    Windows guest and will re-inject them.
4188DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
4189    "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \
4190    "                enable virtual instruction counter with 2^N clock ticks per\n" \
4191    "                instruction, enable aligning the host and virtual clocks\n" \
4192    "                or disable real time cpu sleeping, and optionally enable\n" \
4193    "                record-and-replay mode\n", QEMU_ARCH_ALL)
4195``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]``
4196    Enable virtual instruction counter. The virtual cpu will execute one
4197    instruction every 2^N ns of virtual time. If ``auto`` is specified
4198    then the virtual cpu speed will be automatically adjusted to keep
4199    virtual time within a few seconds of real time.
4201    Note that while this option can give deterministic behavior, it does
4202    not provide cycle accurate emulation. Modern CPUs contain
4203    superscalar out of order cores with complex cache hierarchies. The
4204    number of instructions executed often has little or no correlation
4205    with actual performance.
4207    When the virtual cpu is sleeping, the virtual time will advance at
4208    default speed unless ``sleep=on`` is specified. With
4209    ``sleep=on``, the virtual time will jump to the next timer
4210    deadline instantly whenever the virtual cpu goes to sleep mode and
4211    will not advance if no timer is enabled. This behavior gives
4212    deterministic execution times from the guest point of view.
4213    The default if icount is enabled is ``sleep=off``.
4214    ``sleep=on`` cannot be used together with either ``shift=auto``
4215    or ``align=on``.
4217    ``align=on`` will activate the delay algorithm which will try to
4218    synchronise the host clock and the virtual clock. The goal is to
4219    have a guest running at the real frequency imposed by the shift
4220    option. Whenever the guest clock is behind the host clock and if
4221    ``align=on`` is specified then we print a message to the user to
4222    inform about the delay. Currently this option does not work when
4223    ``shift`` is ``auto``. Note: The sync algorithm will work for those
4224    shift values for which the guest clock runs ahead of the host clock.
4225    Typically this happens when the shift value is high (how high
4226    depends on the host machine). The default if icount is enabled
4227    is ``align=off``.
4229    When the ``rr`` option is specified deterministic record/replay is
4230    enabled. The ``rrfile=`` option must also be provided to
4231    specify the path to the replay log. In record mode data is written
4232    to this file, and in replay mode it is read back.
4233    If the ``rrsnapshot`` option is given then it specifies a VM snapshot
4234    name. In record mode, a new VM snapshot with the given name is created
4235    at the start of execution recording. In replay mode this option
4236    specifies the snapshot name used to load the initial VM state.
4239DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
4240    "-watchdog model\n" \
4241    "                enable virtual hardware watchdog [default=none]\n",
4242    QEMU_ARCH_ALL)
4244``-watchdog model``
4245    Create a virtual hardware watchdog device. Once enabled (by a guest
4246    action), the watchdog must be periodically polled by an agent inside
4247    the guest or else the guest will be restarted. Choose a model for
4248    which your guest has drivers.
4250    The model is the model of hardware watchdog to emulate. Use
4251    ``-watchdog help`` to list available hardware models. Only one
4252    watchdog can be enabled for a guest.
4254    The following models may be available:
4256    ``ib700``
4257        iBASE 700 is a very simple ISA watchdog with a single timer.
4259    ``i6300esb``
4260        Intel 6300ESB I/O controller hub is a much more featureful
4261        PCI-based dual-timer watchdog.
4263    ``diag288``
4264        A virtual watchdog for s390x backed by the diagnose 288
4265        hypercall (currently KVM only).
4268DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
4269    "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
4270    "                action when watchdog fires [default=reset]\n",
4271    QEMU_ARCH_ALL)
4273``-watchdog-action action``
4274    The action controls what QEMU will do when the watchdog timer
4275    expires. The default is ``reset`` (forcefully reset the guest).
4276    Other possible actions are: ``shutdown`` (attempt to gracefully
4277    shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
4278    ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
4279    guest), ``debug`` (print a debug message and continue), or ``none``
4280    (do nothing).
4282    Note that the ``shutdown`` action requires that the guest responds
4283    to ACPI signals, which it may not be able to do in the sort of
4284    situations where the watchdog would have expired, and thus
4285    ``-watchdog-action shutdown`` is not recommended for production use.
4287    Examples:
4289    ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700``
4293DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
4294    "-echr chr       set terminal escape character instead of ctrl-a\n",
4295    QEMU_ARCH_ALL)
4297``-echr numeric_ascii_value``
4298    Change the escape character used for switching to the monitor when
4299    using monitor and serial sharing. The default is ``0x01`` when using
4300    the ``-nographic`` option. ``0x01`` is equal to pressing
4301    ``Control-a``. You can select a different character from the ascii
4302    control keys where 1 through 26 map to Control-a through Control-z.
4303    For instance you could use the either of the following to change the
4304    escape character to Control-t.
4306    ``-echr 0x14``; \ ``-echr 20``
4310DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
4311    "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \
4312    "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \
4313    "-incoming unix:socketpath\n" \
4314    "                prepare for incoming migration, listen on\n" \
4315    "                specified protocol and socket address\n" \
4316    "-incoming fd:fd\n" \
4317    "-incoming exec:cmdline\n" \
4318    "                accept incoming migration on given file descriptor\n" \
4319    "                or from given external command\n" \
4320    "-incoming defer\n" \
4321    "                wait for the URI to be specified via migrate_incoming\n",
4322    QEMU_ARCH_ALL)
4324``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]``
4325  \ 
4326``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]``
4327    Prepare for incoming migration, listen on a given tcp port.
4329``-incoming unix:socketpath``
4330    Prepare for incoming migration, listen on a given unix socket.
4332``-incoming fd:fd``
4333    Accept incoming migration from a given filedescriptor.
4335``-incoming exec:cmdline``
4336    Accept incoming migration as an output from specified external
4337    command.
4339``-incoming defer``
4340    Wait for the URI to be specified via migrate\_incoming. The monitor
4341    can be used to change settings (such as migration parameters) prior
4342    to issuing the migrate\_incoming to allow the migration to begin.
4345DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
4346    "-only-migratable     allow only migratable devices\n", QEMU_ARCH_ALL)
4349    Only allow migratable devices. Devices will not be allowed to enter
4350    an unmigratable state.
4353DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
4354    "-nodefaults     don't create default devices\n", QEMU_ARCH_ALL)
4357    Don't create default devices. Normally, QEMU sets the default
4358    devices like serial port, parallel port, virtual console, monitor
4359    device, VGA adapter, floppy and CD-ROM drive and others. The
4360    ``-nodefaults`` option will disable all those default devices.
4363#ifndef _WIN32
4364DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
4365    "-chroot dir     chroot to dir just before starting the VM\n",
4366    QEMU_ARCH_ALL)
4369``-chroot dir``
4370    Immediately before starting guest execution, chroot to the specified
4371    directory. Especially useful in combination with -runas.
4374#ifndef _WIN32
4375DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
4376    "-runas user     change to user id user just before starting the VM\n" \
4377    "                user can be numeric uid:gid instead\n",
4378    QEMU_ARCH_ALL)
4381``-runas user``
4382    Immediately before starting guest execution, drop root privileges,
4383    switching to the specified user.
4386DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
4387    "-prom-env variable=value\n"
4388    "                set OpenBIOS nvram variables\n",
4391``-prom-env variable=value``
4392    Set OpenBIOS nvram variable to given value (PPC, SPARC only).
4394    ::
4396        qemu-system-sparc -prom-env 'auto-boot?=false' \
4397         -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
4399    ::
4401        qemu-system-ppc -prom-env 'auto-boot?=false' \
4402         -prom-env 'boot-device=hd:2,\yaboot' \
4403         -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
4405DEF("semihosting", 0, QEMU_OPTION_semihosting,
4406    "-semihosting    semihosting mode\n",
4411    Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only).
4413    Note that this allows guest direct access to the host filesystem, so
4414    should only be used with a trusted guest OS.
4416    See the -semihosting-config option documentation for further
4417    information about the facilities this enables.
4419DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
4420    "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
4421    "                semihosting configuration\n",
4425``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]``
4426    Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V
4427    only).
4429    Note that this allows guest direct access to the host filesystem, so
4430    should only be used with a trusted guest OS.
4432    On Arm this implements the standard semihosting API, version 2.0.
4434    On M68K this implements the "ColdFire GDB" interface used by
4435    libgloss.
4437    Xtensa semihosting provides basic file IO calls, such as
4438    open/read/write/seek/select. Tensilica baremetal libc for ISS and
4439    linux platform "sim" use this interface.
4441    On RISC-V this implements the standard semihosting API, version 0.2.
4443    ``target=native|gdb|auto``
4444        Defines where the semihosting calls will be addressed, to QEMU
4445        (``native``) or to GDB (``gdb``). The default is ``auto``, which
4446        means ``gdb`` during debug sessions and ``native`` otherwise.
4448    ``chardev=str1``
4449        Send the output to a chardev backend output for native or auto
4450        output when not in gdb
4452    ``arg=str1,arg=str2,...``
4453        Allows the user to pass input arguments, and can be used
4454        multiple times to build up a list. The old-style
4455        ``-kernel``/``-append`` method of passing a command line is
4456        still supported for backward compatibility. If both the
4457        ``--semihosting-config arg`` and the ``-kernel``/``-append`` are
4458        specified, the former is passed to semihosting as it always
4459        takes precedence.
4461DEF("old-param", 0, QEMU_OPTION_old_param,
4462    "-old-param      old param mode\n", QEMU_ARCH_ARM)
4465    Old param mode (ARM only).
4468DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
4469    "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4470    "          [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4471    "                Enable seccomp mode 2 system call filter (default 'off').\n" \
4472    "                use 'obsolete' to allow obsolete system calls that are provided\n" \
4473    "                    by the kernel, but typically no longer used by modern\n" \
4474    "                    C library implementations.\n" \
4475    "                use 'elevateprivileges' to allow or deny the QEMU process ability\n" \
4476    "                    to elevate privileges using set*uid|gid system calls.\n" \
4477    "                    The value 'children' will deny set*uid|gid system calls for\n" \
4478    "                    main QEMU process but will allow forks and execves to run unprivileged\n" \
4479    "                use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4480    "                     blocking *fork and execve\n" \
4481    "                use 'resourcecontrol' to disable process affinity and schedular priority\n",
4482    QEMU_ARCH_ALL)
4484``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]``
4485    Enable Seccomp mode 2 system call filter. 'on' will enable syscall
4486    filtering and 'off' will disable it. The default is 'off'.
4488    ``obsolete=string``
4489        Enable Obsolete system calls
4491    ``elevateprivileges=string``
4492        Disable set\*uid\|gid system calls
4494    ``spawn=string``
4495        Disable \*fork and execve
4497    ``resourcecontrol=string``
4498        Disable process affinity and schedular priority
4501DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
4502    "-readconfig <file>\n", QEMU_ARCH_ALL)
4504``-readconfig file``
4505    Read device configuration from file. This approach is useful when
4506    you want to spawn QEMU process with many command line options but
4507    you don't want to exceed the command line character limit.
4509DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
4510    "-writeconfig <file>\n"
4511    "                read/write config file (deprecated)\n", QEMU_ARCH_ALL)
4515DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4516    "-no-user-config\n"
4517    "                do not load default user-provided config files at startup\n",
4518    QEMU_ARCH_ALL)
4521    The ``-no-user-config`` option makes QEMU not load any of the
4522    user-provided config files on sysconfdir.
4525DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4526    "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4527    "                specify tracing options\n",
4528    QEMU_ARCH_ALL)
4530``-trace [[enable=]pattern][,events=file][,file=file]``
4531  .. include:: ../qemu-option-trace.rst.inc
4534DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4535    "-plugin [file=]<file>[,arg=<string>]\n"
4536    "                load a plugin\n",
4537    QEMU_ARCH_ALL)
4539``-plugin file=file[,arg=string]``
4540    Load a plugin.
4542    ``file=file``
4543        Load the given plugin from a shared library file.
4545    ``arg=string``
4546        Argument string passed to the plugin. (Can be given multiple
4547        times.)
4550HXCOMM Internal use
4551DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4552DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4554#ifdef __linux__
4555DEF("enable-fips", 0, QEMU_OPTION_enablefips,
4556    "-enable-fips    enable FIPS 140-2 compliance\n",
4557    QEMU_ARCH_ALL)
4561    Enable FIPS 140-2 compliance mode.
4564DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4565    "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
4566    "                control error message format\n"
4567    "                timestamp=on enables timestamps (default: off)\n"
4568    "                guest-name=on enables guest name prefix but only if\n"
4569    "                              -name guest option is set (default: off)\n",
4570    QEMU_ARCH_ALL)
4572``-msg [timestamp[=on|off]][,guest-name[=on|off]]``
4573    Control error message format.
4575    ``timestamp=on|off``
4576        Prefix messages with a timestamp. Default is off.
4578    ``guest-name=on|off``
4579        Prefix messages with guest name but only if -name guest option is set
4580        otherwise the option is ignored. Default is off.
4583DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
4584    "-dump-vmstate <file>\n"
4585    "                Output vmstate information in JSON format to file.\n"
4586    "                Use the scripts/vmstate-static-checker.py file to\n"
4587    "                check for possible regressions in migration code\n"
4588    "                by comparing two such vmstate dumps.\n",
4589    QEMU_ARCH_ALL)
4591``-dump-vmstate file``
4592    Dump json-encoded vmstate information for current machine type to
4593    file in file
4596DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
4597    "-enable-sync-profile\n"
4598    "                enable synchronization profiling\n",
4599    QEMU_ARCH_ALL)
4602    Enable synchronization profiling.
4607DEFHEADING(Generic object creation:)
4609DEF("object", HAS_ARG, QEMU_OPTION_object,
4610    "-object TYPENAME[,PROP1=VALUE1,...]\n"
4611    "                create a new object of type TYPENAME setting properties\n"
4612    "                in the order they are specified.  Note that the 'id'\n"
4613    "                property must be set.  These objects are placed in the\n"
4614    "                '/objects' path.\n",
4615    QEMU_ARCH_ALL)
4617``-object typename[,prop1=value1,...]``
4618    Create a new object of type typename setting properties in the order
4619    they are specified. Note that the 'id' property must be set. These
4620    objects are placed in the '/objects' path.
4622    ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,readonly=on|off``
4623        Creates a memory file backend object, which can be used to back
4624        the guest RAM with huge pages.
4626        The ``id`` parameter is a unique ID that will be used to
4627        reference this memory region in other parameters, e.g. ``-numa``,
4628        ``-device nvdimm``, etc.
4630        The ``size`` option provides the size of the memory region, and
4631        accepts common suffixes, e.g. ``500M``.
4633        The ``mem-path`` provides the path to either a shared memory or
4634        huge page filesystem mount.
4636        The ``share`` boolean option determines whether the memory
4637        region is marked as private to QEMU, or shared. The latter
4638        allows a co-operating external process to access the QEMU memory
4639        region.
4641        The ``share`` is also required for pvrdma devices due to
4642        limitations in the RDMA API provided by Linux.
4644        Setting share=on might affect the ability to configure NUMA
4645        bindings for the memory backend under some circumstances, see
4646        Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
4647        source tree for additional details.
4649        Setting the ``discard-data`` boolean option to on indicates that
4650        file contents can be destroyed when QEMU exits, to avoid
4651        unnecessarily flushing data to the backing file. Note that
4652        ``discard-data`` is only an optimization, and QEMU might not
4653        discard file contents if it aborts unexpectedly or is terminated
4654        using SIGKILL.
4656        The ``merge`` boolean option enables memory merge, also known as
4657        MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
4658        the pages for memory deduplication.
4660        Setting the ``dump`` boolean option to off excludes the memory
4661        from core dumps. This feature is also known as MADV\_DONTDUMP.
4663        The ``prealloc`` boolean option enables memory preallocation.
4665        The ``host-nodes`` option binds the memory range to a list of
4666        NUMA host nodes.
4668        The ``policy`` option sets the NUMA policy to one of the
4669        following values:
4671        ``default``
4672            default host policy
4674        ``preferred``
4675            prefer the given host node list for allocation
4677        ``bind``
4678            restrict memory allocation to the given host node list
4680        ``interleave``
4681            interleave memory allocations across the given host node
4682            list
4684        The ``align`` option specifies the base address alignment when
4685        QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
4686        ``2M``. Some backend store specified by ``mem-path`` requires an
4687        alignment different than the default one used by QEMU, eg the
4688        device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
4689        such cases, users can specify the required alignment via this
4690        option.
4692        The ``pmem`` option specifies whether the backing file specified
4693        by ``mem-path`` is in host persistent memory that can be
4694        accessed using the SNIA NVM programming model (e.g. Intel
4695        NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary
4696        operations to guarantee the persistence of its own writes to
4697        ``mem-path`` (e.g. in vNVDIMM label emulation and live
4698        migration). Also, we will map the backend-file with MAP\_SYNC
4699        flag, which ensures the file metadata is in sync for
4700        ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
4701        requires support from both the host kernel (since Linux kernel
4702        4.15) and the filesystem of ``mem-path`` mounted with DAX
4703        option.
4705        The ``readonly`` option specifies whether the backing file is opened
4706        read-only or read-write (default).
4708    ``-object memory-backend-ram,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave``
4709        Creates a memory backend object, which can be used to back the
4710        guest RAM. Memory backend objects offer more control than the
4711        ``-m`` option that is traditionally used to define guest RAM.
4712        Please refer to ``memory-backend-file`` for a description of the
4713        options.
4715    ``-object memory-backend-memfd,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave,seal=on|off,hugetlb=on|off,hugetlbsize=size``
4716        Creates an anonymous memory file backend object, which allows
4717        QEMU to share the memory with an external process (e.g. when
4718        using vhost-user). The memory is allocated with memfd and
4719        optional sealing. (Linux only)
4721        The ``seal`` option creates a sealed-file, that will block
4722        further resizing the memory ('on' by default).
4724        The ``hugetlb`` option specify the file to be created resides in
4725        the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
4726        with the ``hugetlb`` option, the ``hugetlbsize`` option specify
4727        the hugetlb page size on systems that support multiple hugetlb
4728        page sizes (it must be a power of 2 value supported by the
4729        system).
4731        In some versions of Linux, the ``hugetlb`` option is
4732        incompatible with the ``seal`` option (requires at least Linux
4733        4.16).
4735        Please refer to ``memory-backend-file`` for a description of the
4736        other options.
4738        The ``share`` boolean option is on by default with memfd.
4740    ``-object rng-builtin,id=id``
4741        Creates a random number generator backend which obtains entropy
4742        from QEMU builtin functions. The ``id`` parameter is a unique ID
4743        that will be used to reference this entropy backend from the
4744        ``virtio-rng`` device. By default, the ``virtio-rng`` device
4745        uses this RNG backend.
4747    ``-object rng-random,id=id,filename=/dev/random``
4748        Creates a random number generator backend which obtains entropy
4749        from a device on the host. The ``id`` parameter is a unique ID
4750        that will be used to reference this entropy backend from the
4751        ``virtio-rng`` device. The ``filename`` parameter specifies
4752        which file to obtain entropy from and if omitted defaults to
4753        ``/dev/urandom``.
4755    ``-object rng-egd,id=id,chardev=chardevid``
4756        Creates a random number generator backend which obtains entropy
4757        from an external daemon running on the host. The ``id``
4758        parameter is a unique ID that will be used to reference this
4759        entropy backend from the ``virtio-rng`` device. The ``chardev``
4760        parameter is the unique ID of a character device backend that
4761        provides the connection to the RNG daemon.
4763    ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
4764        Creates a TLS anonymous credentials object, which can be used to
4765        provide TLS support on network backends. The ``id`` parameter is
4766        a unique ID which network backends will use to access the
4767        credentials. The ``endpoint`` is either ``server`` or ``client``
4768        depending on whether the QEMU network backend that uses the
4769        credentials will be acting as a client or as a server. If
4770        ``verify-peer`` is enabled (the default) then once the handshake
4771        is completed, the peer credentials will be verified, though this
4772        is a no-op for anonymous credentials.
4774        The dir parameter tells QEMU where to find the credential files.
4775        For server endpoints, this directory may contain a file
4776        dh-params.pem providing diffie-hellman parameters to use for the
4777        TLS server. If the file is missing, QEMU will generate a set of
4778        DH parameters at startup. This is a computationally expensive
4779        operation that consumes random pool entropy, so it is
4780        recommended that a persistent set of parameters be generated
4781        upfront and saved.
4783    ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
4784        Creates a TLS Pre-Shared Keys (PSK) credentials object, which
4785        can be used to provide TLS support on network backends. The
4786        ``id`` parameter is a unique ID which network backends will use
4787        to access the credentials. The ``endpoint`` is either ``server``
4788        or ``client`` depending on whether the QEMU network backend that
4789        uses the credentials will be acting as a client or as a server.
4790        For clients only, ``username`` is the username which will be
4791        sent to the server. If omitted it defaults to "qemu".
4793        The dir parameter tells QEMU where to find the keys file. It is
4794        called "dir/keys.psk" and contains "username:key" pairs. This
4795        file can most easily be created using the GnuTLS ``psktool``
4796        program.
4798        For server endpoints, dir may also contain a file dh-params.pem
4799        providing diffie-hellman parameters to use for the TLS server.
4800        If the file is missing, QEMU will generate a set of DH
4801        parameters at startup. This is a computationally expensive
4802        operation that consumes random pool entropy, so it is
4803        recommended that a persistent set of parameters be generated up
4804        front and saved.
4806    ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
4807        Creates a TLS anonymous credentials object, which can be used to
4808        provide TLS support on network backends. The ``id`` parameter is
4809        a unique ID which network backends will use to access the
4810        credentials. The ``endpoint`` is either ``server`` or ``client``
4811        depending on whether the QEMU network backend that uses the
4812        credentials will be acting as a client or as a server. If
4813        ``verify-peer`` is enabled (the default) then once the handshake
4814        is completed, the peer credentials will be verified. With x509
4815        certificates, this implies that the clients must be provided
4816        with valid client certificates too.
4818        The dir parameter tells QEMU where to find the credential files.
4819        For server endpoints, this directory may contain a file
4820        dh-params.pem providing diffie-hellman parameters to use for the
4821        TLS server. If the file is missing, QEMU will generate a set of
4822        DH parameters at startup. This is a computationally expensive
4823        operation that consumes random pool entropy, so it is
4824        recommended that a persistent set of parameters be generated
4825        upfront and saved.
4827        For x509 certificate credentials the directory will contain
4828        further files providing the x509 certificates. The certificates
4829        must be stored in PEM format, in filenames ca-cert.pem,
4830        ca-crl.pem (optional), server-cert.pem (only servers),
4831        server-key.pem (only servers), client-cert.pem (only clients),
4832        and client-key.pem (only clients).
4834        For the server-key.pem and client-key.pem files which contain
4835        sensitive private keys, it is possible to use an encrypted
4836        version by providing the passwordid parameter. This provides the
4837        ID of a previously created ``secret`` object containing the
4838        password for decryption.
4840        The priority parameter allows to override the global default
4841        priority used by gnutls. This can be useful if the system
4842        administrator needs to use a weaker set of crypto priorities for
4843        QEMU without potentially forcing the weakness onto all
4844        applications. Or conversely if one wants wants a stronger
4845        default for QEMU than for all other applications, they can do
4846        this through this parameter. Its format is a gnutls priority
4847        string as described at
4848        https://gnutls.org/manual/html_node/Priority-Strings.html.
4850    ``-object tls-cipher-suites,id=id,priority=priority``
4851        Creates a TLS cipher suites object, which can be used to control
4852        the TLS cipher/protocol algorithms that applications are permitted
4853        to use.
4855        The ``id`` parameter is a unique ID which frontends will use to
4856        access the ordered list of permitted TLS cipher suites from the
4857        host.
4859        The ``priority`` parameter allows to override the global default
4860        priority used by gnutls. This can be useful if the system
4861        administrator needs to use a weaker set of crypto priorities for
4862        QEMU without potentially forcing the weakness onto all
4863        applications. Or conversely if one wants wants a stronger
4864        default for QEMU than for all other applications, they can do
4865        this through this parameter. Its format is a gnutls priority
4866        string as described at
4867        https://gnutls.org/manual/html_node/Priority-Strings.html.
4869        An example of use of this object is to control UEFI HTTPS Boot.
4870        The tls-cipher-suites object exposes the ordered list of permitted
4871        TLS cipher suites from the host side to the guest firmware, via
4872        fw_cfg. The list is represented as an array of IANA_TLS_CIPHER
4873        objects. The firmware uses the IANA_TLS_CIPHER array for configuring
4874        guest-side TLS.
4876        In the following example, the priority at which the host-side policy
4877        is retrieved is given by the ``priority`` property.
4878        Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to
4879        refer to /etc/crypto-policies/back-ends/gnutls.config.
4881        .. parsed-literal::
4883             # |qemu_system| \\
4884                 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\
4885                 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0
4887    ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
4888        Interval t can't be 0, this filter batches the packet delivery:
4889        all packets arriving in a given interval on netdev netdevid are
4890        delayed until the end of the interval. Interval is in
4891        microseconds. ``status`` is optional that indicate whether the
4892        netfilter is on (enabled) or off (disabled), the default status
4893        for netfilter will be 'on'.
4895        queue all\|rx\|tx is an option that can be applied to any
4896        netfilter.
4898        ``all``: the filter is attached both to the receive and the
4899        transmit queue of the netdev (default).
4901        ``rx``: the filter is attached to the receive queue of the
4902        netdev, where it will receive packets sent to the netdev.
4904        ``tx``: the filter is attached to the transmit queue of the
4905        netdev, where it will receive packets sent by the netdev.
4907        position head\|tail\|id=<id> is an option to specify where the
4908        filter should be inserted in the filter list. It can be applied
4909        to any netfilter.
4911        ``head``: the filter is inserted at the head of the filter list,
4912        before any existing filters.
4914        ``tail``: the filter is inserted at the tail of the filter list,
4915        behind any existing filters (default).
4917        ``id=<id>``: the filter is inserted before or behind the filter
4918        specified by <id>, see the insert option below.
4920        insert behind\|before is an option to specify where to insert
4921        the new filter relative to the one specified with
4922        position=id=<id>. It can be applied to any netfilter.
4924        ``before``: insert before the specified filter.
4926        ``behind``: insert behind the specified filter (default).
4928    ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4929        filter-mirror on netdev netdevid,mirror net packet to
4930        chardevchardevid, if it has the vnet\_hdr\_support flag,
4931        filter-mirror will mirror packet with vnet\_hdr\_len.
4933    ``-object filter-redirector,id=id,netdev=netdevid,indev=chardevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4934        filter-redirector on netdev netdevid,redirect filter's net
4935        packet to chardev chardevid,and redirect indev's packet to
4936        filter.if it has the vnet\_hdr\_support flag, filter-redirector
4937        will redirect packet with vnet\_hdr\_len. Create a
4938        filter-redirector we need to differ outdev id from indev id, id
4939        can not be the same. we can just use indev or outdev, but at
4940        least one of indev or outdev need to be specified.
4942    ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4943        Filter-rewriter is a part of COLO project.It will rewrite tcp
4944        packet to secondary from primary to keep secondary tcp
4945        connection,and rewrite tcp packet to primary from secondary make
4946        tcp packet can be handled by client.if it has the
4947        vnet\_hdr\_support flag, we can parse packet with vnet header.
4949        usage: colo secondary: -object
4950        filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object
4951        filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object
4952        filter-rewriter,id=rew0,netdev=hn0,queue=all
4954    ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]``
4955        Dump the network traffic on netdev dev to the file specified by
4956        filename. At most len bytes (64k by default) per packet are
4957        stored. The file format is libpcap, so it can be analyzed with
4958        tools such as tcpdump or Wireshark.
4960    ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id][,compare_timeout=@var{ms}][,expired_scan_cycle=@var{ms}][,max_queue_size=@var{size}]``
4961        Colo-compare gets packet from primary\_in chardevid and
4962        secondary\_in, then compare whether the payload of primary packet
4963        and secondary packet are the same. If same, it will output
4964        primary packet to out\_dev, else it will notify COLO-framework to do
4965        checkpoint and send primary packet to out\_dev. In order to
4966        improve efficiency, we need to put the task of comparison in
4967        another iothread. If it has the vnet\_hdr\_support flag,
4968        colo compare will send/recv packet with vnet\_hdr\_len.
4969        The compare\_timeout=@var{ms} determines the maximum time of the
4970        colo-compare hold the packet. The expired\_scan\_cycle=@var{ms}
4971        is to set the period of scanning expired primary node network packets.
4972        The max\_queue\_size=@var{size} is to set the max compare queue
4973        size depend on user environment.
4974        If user want to use Xen COLO, need to add the notify\_dev to
4975        notify Xen colo-frame to do checkpoint.
4977        COLO-compare must be used with the help of filter-mirror,
4978        filter-redirector and filter-rewriter.
4980        ::
4982            KVM COLO
4984            primary:
4985            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4986            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4987            -chardev socket,id=mirror0,host=,port=9003,server=on,wait=off
4988            -chardev socket,id=compare1,host=,port=9004,server=on,wait=off
4989            -chardev socket,id=compare0,host=,port=9001,server=on,wait=off
4990            -chardev socket,id=compare0-0,host=,port=9001
4991            -chardev socket,id=compare_out,host=,port=9005,server=on,wait=off
4992            -chardev socket,id=compare_out0,host=,port=9005
4993            -object iothread,id=iothread1
4994            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4995            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4996            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4997            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
4999            secondary:
5000            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
5001            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5002            -chardev socket,id=red0,host=,port=9003
5003            -chardev socket,id=red1,host=,port=9004
5004            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5005            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5008            Xen COLO
5010            primary:
5011            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
5012            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
5013            -chardev socket,id=mirror0,host=,port=9003,server=on,wait=off
5014            -chardev socket,id=compare1,host=,port=9004,server=on,wait=off
5015            -chardev socket,id=compare0,host=,port=9001,server=on,wait=off
5016            -chardev socket,id=compare0-0,host=,port=9001
5017            -chardev socket,id=compare_out,host=,port=9005,server=on,wait=off
5018            -chardev socket,id=compare_out0,host=,port=9005
5019            -chardev socket,id=notify_way,host=,port=9009,server=on,wait=off
5020            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
5021            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
5022            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
5023            -object iothread,id=iothread1
5024            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1
5026            secondary:
5027            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
5028            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5029            -chardev socket,id=red0,host=,port=9003
5030            -chardev socket,id=red1,host=,port=9004
5031            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5032            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5034        If you want to know the detail of above command line, you can
5035        read the colo-compare git log.
5037    ``-object cryptodev-backend-builtin,id=id[,queues=queues]``
5038        Creates a cryptodev backend which executes crypto opreation from
5039        the QEMU cipher APIS. The id parameter is a unique ID that will
5040        be used to reference this cryptodev backend from the
5041        ``virtio-crypto`` device. The queues parameter is optional,
5042        which specify the queue number of cryptodev backend, the default
5043        of queues is 1.
5045        .. parsed-literal::
5047             # |qemu_system| \\
5048               [...] \\
5049                   -object cryptodev-backend-builtin,id=cryptodev0 \\
5050                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5051               [...]
5053    ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]``
5054        Creates a vhost-user cryptodev backend, backed by a chardev
5055        chardevid. The id parameter is a unique ID that will be used to
5056        reference this cryptodev backend from the ``virtio-crypto``
5057        device. The chardev should be a unix domain socket backed one.
5058        The vhost-user uses a specifically defined protocol to pass
5059        vhost ioctl replacement messages to an application on the other
5060        end of the socket. The queues parameter is optional, which
5061        specify the queue number of cryptodev backend for multiqueue
5062        vhost-user, the default of queues is 1.
5064        .. parsed-literal::
5066             # |qemu_system| \\
5067               [...] \\
5068                   -chardev socket,id=chardev0,path=/path/to/socket \\
5069                   -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\
5070                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5071               [...]
5073    ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]``
5074      \ 
5075    ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]``
5076        Defines a secret to store a password, encryption key, or some
5077        other sensitive data. The sensitive data can either be passed
5078        directly via the data parameter, or indirectly via the file
5079        parameter. Using the data parameter is insecure unless the
5080        sensitive data is encrypted.
5082        The sensitive data can be provided in raw format (the default),
5083        or base64. When encoded as JSON, the raw format only supports
5084        valid UTF-8 characters, so base64 is recommended for sending
5085        binary data. QEMU will convert from which ever format is
5086        provided to the format it needs internally. eg, an RBD password
5087        can be provided in raw format, even though it will be base64
5088        encoded when passed onto the RBD sever.
5090        For added protection, it is possible to encrypt the data
5091        associated with a secret using the AES-256-CBC cipher. Use of
5092        encryption is indicated by providing the keyid and iv
5093        parameters. The keyid parameter provides the ID of a previously
5094        defined secret that contains the AES-256 decryption key. This
5095        key should be 32-bytes long and be base64 encoded. The iv
5096        parameter provides the random initialization vector used for
5097        encryption of this particular secret and should be a base64
5098        encrypted string of the 16-byte IV.
5100        The simplest (insecure) usage is to provide the secret inline
5102        .. parsed-literal::
5104             # |qemu_system| -object secret,id=sec0,data=letmein,format=raw
5106        The simplest secure usage is to provide the secret via a file
5108        # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object
5109        secret,id=sec0,file=mypasswd.txt,format=raw
5111        For greater security, AES-256-CBC should be used. To illustrate
5112        usage, consider the openssl command line tool which can encrypt
5113        the data. Note that when encrypting, the plaintext must be
5114        padded to the cipher block size (32 bytes) using the standard
5115        PKCS#5/6 compatible padding algorithm.
5117        First a master key needs to be created in base64 encoding:
5119        ::
5121             # openssl rand -base64 32 > key.b64
5122             # KEY=$(base64 -d key.b64 | hexdump  -v -e '/1 "%02X"')
5124        Each secret to be encrypted needs to have a random
5125        initialization vector generated. These do not need to be kept
5126        secret
5128        ::
5130             # openssl rand -base64 16 > iv.b64
5131             # IV=$(base64 -d iv.b64 | hexdump  -v -e '/1 "%02X"')
5133        The secret to be defined can now be encrypted, in this case
5134        we're telling openssl to base64 encode the result, but it could
5135        be left as raw bytes if desired.
5137        ::
5139             # SECRET=$(printf "letmein" |
5140                        openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
5142        When launching QEMU, create a master secret pointing to
5143        ``key.b64`` and specify that to be used to decrypt the user
5144        password. Pass the contents of ``iv.b64`` to the second secret
5146        .. parsed-literal::
5148             # |qemu_system| \\
5149                 -object secret,id=secmaster0,format=base64,file=key.b64 \\
5150                 -object secret,id=sec0,keyid=secmaster0,format=base64,\\
5151                     data=$SECRET,iv=$(<iv.b64)
5153    ``-object sev-guest,id=id,cbitpos=cbitpos,reduced-phys-bits=val,[sev-device=string,policy=policy,handle=handle,dh-cert-file=file,session-file=file]``
5154        Create a Secure Encrypted Virtualization (SEV) guest object,
5155        which can be used to provide the guest memory encryption support
5156        on AMD processors.
5158        When memory encryption is enabled, one of the physical address
5159        bit (aka the C-bit) is utilized to mark if a memory page is
5160        protected. The ``cbitpos`` is used to provide the C-bit
5161        position. The C-bit position is Host family dependent hence user
5162        must provide this value. On EPYC, the value should be 47.
5164        When memory encryption is enabled, we loose certain bits in
5165        physical address space. The ``reduced-phys-bits`` is used to
5166        provide the number of bits we loose in physical address space.
5167        Similar to C-bit, the value is Host family dependent. On EPYC,
5168        the value should be 5.
5170        The ``sev-device`` provides the device file to use for
5171        communicating with the SEV firmware running inside AMD Secure
5172        Processor. The default device is '/dev/sev'. If hardware
5173        supports memory encryption then /dev/sev devices are created by
5174        CCP driver.
5176        The ``policy`` provides the guest policy to be enforced by the
5177        SEV firmware and restrict what configuration and operational
5178        commands can be performed on this guest by the hypervisor. The
5179        policy should be provided by the guest owner and is bound to the
5180        guest and cannot be changed throughout the lifetime of the
5181        guest. The default is 0.
5183        If guest ``policy`` allows sharing the key with another SEV
5184        guest then ``handle`` can be use to provide handle of the guest
5185        from which to share the key.
5187        The ``dh-cert-file`` and ``session-file`` provides the guest
5188        owner's Public Diffie-Hillman key defined in SEV spec. The PDH
5189        and session parameters are used for establishing a cryptographic
5190        session with the guest owner to negotiate keys used for
5191        attestation. The file must be encoded in base64.
5193        e.g to launch a SEV guest
5195        .. parsed-literal::
5197             # |qemu_system_x86| \\
5198                 ...... \\
5199                 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\
5200                 -machine ...,memory-encryption=sev0 \\
5201                 .....
5203    ``-object authz-simple,id=id,identity=string``
5204        Create an authorization object that will control access to
5205        network services.
5207        The ``identity`` parameter is identifies the user and its format
5208        depends on the network service that authorization object is
5209        associated with. For authorizing based on TLS x509 certificates,
5210        the identity must be the x509 distinguished name. Note that care
5211        must be taken to escape any commas in the distinguished name.
5213        An example authorization object to validate a x509 distinguished
5214        name would look like:
5216        .. parsed-literal::
5218             # |qemu_system| \\
5219                 ... \\
5220                 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\
5221                 ...
5223        Note the use of quotes due to the x509 distinguished name
5224        containing whitespace, and escaping of ','.
5226    ``-object authz-listfile,id=id,filename=path,refresh=on|off``
5227        Create an authorization object that will control access to
5228        network services.
5230        The ``filename`` parameter is the fully qualified path to a file
5231        containing the access control list rules in JSON format.
5233        An example set of rules that match against SASL usernames might
5234        look like:
5236        ::
5238              {
5239                "rules": [
5240                   { "match": "fred", "policy": "allow", "format": "exact" },
5241                   { "match": "bob", "policy": "allow", "format": "exact" },
5242                   { "match": "danb", "policy": "deny", "format": "glob" },
5243                   { "match": "dan*", "policy": "allow", "format": "exact" },
5244                ],
5245                "policy": "deny"
5246              }
5248        When checking access the object will iterate over all the rules
5249        and the first rule to match will have its ``policy`` value
5250        returned as the result. If no rules match, then the default
5251        ``policy`` value is returned.
5253        The rules can either be an exact string match, or they can use
5254        the simple UNIX glob pattern matching to allow wildcards to be
5255        used.
5257        If ``refresh`` is set to true the file will be monitored and
5258        automatically reloaded whenever its content changes.
5260        As with the ``authz-simple`` object, the format of the identity
5261        strings being matched depends on the network service, but is
5262        usually a TLS x509 distinguished name, or a SASL username.
5264        An example authorization object to validate a SASL username
5265        would look like:
5267        .. parsed-literal::
5269             # |qemu_system| \\
5270                 ... \\
5271                 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\
5272                 ...
5274    ``-object authz-pam,id=id,service=string``
5275        Create an authorization object that will control access to
5276        network services.
5278        The ``service`` parameter provides the name of a PAM service to
5279        use for authorization. It requires that a file
5280        ``/etc/pam.d/service`` exist to provide the configuration for
5281        the ``account`` subsystem.
5283        An example authorization object to validate a TLS x509
5284        distinguished name would look like:
5286        .. parsed-literal::
5288             # |qemu_system| \\
5289                 ... \\
5290                 -object authz-pam,id=auth0,service=qemu-vnc \\
5291                 ...
5293        There would then be a corresponding config file for PAM at
5294        ``/etc/pam.d/qemu-vnc`` that contains:
5296        ::
5298            account requisite  pam_listfile.so item=user sense=allow \
5299                       file=/etc/qemu/vnc.allow
5301        Finally the ``/etc/qemu/vnc.allow`` file would contain the list
5302        of x509 distingished names that are permitted access
5304        ::
5306            CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
5308    ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch``
5309        Creates a dedicated event loop thread that devices can be
5310        assigned to. This is known as an IOThread. By default device
5311        emulation happens in vCPU threads or the main event loop thread.
5312        This can become a scalability bottleneck. IOThreads allow device
5313        emulation and I/O to run on other host CPUs.
5315        The ``id`` parameter is a unique ID that will be used to
5316        reference this IOThread from ``-device ...,iothread=id``.
5317        Multiple devices can be assigned to an IOThread. Note that not
5318        all devices support an ``iothread`` parameter.
5320        The ``query-iothreads`` QMP command lists IOThreads and reports
5321        their thread IDs so that the user can configure host CPU
5322        pinning/affinity.
5324        IOThreads use an adaptive polling algorithm to reduce event loop
5325        latency. Instead of entering a blocking system call to monitor
5326        file descriptors and then pay the cost of being woken up when an
5327        event occurs, the polling algorithm spins waiting for events for
5328        a short time. The algorithm's default parameters are suitable
5329        for many cases but can be adjusted based on knowledge of the
5330        workload and/or host device latency.
5332        The ``poll-max-ns`` parameter is the maximum number of
5333        nanoseconds to busy wait for events. Polling can be disabled by
5334        setting this value to 0.
5336        The ``poll-grow`` parameter is the multiplier used to increase
5337        the polling time when the algorithm detects it is missing events
5338        due to not polling long enough.
5340        The ``poll-shrink`` parameter is the divisor used to decrease
5341        the polling time when the algorithm detects it is spending too
5342        long polling without encountering events.
5344        The ``aio-max-batch`` parameter is the maximum number of requests
5345        in a batch for the AIO engine, 0 means that the engine will use
5346        its default.
5348        The IOThread parameters can be modified at run-time using the
5349        ``qom-set`` command (where ``iothread1`` is the IOThread's
5350        ``id``):
5352        ::
5354            (qemu) qom-set /objects/iothread1 poll-max-ns 100000
5358HXCOMM This is the last statement. Insert new options before this line!
5360#undef DEF
5361#undef DEFHEADING
5362#undef ARCHHEADING