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
 130    "                sgx-epc.0.memdev=memid\n",
 131    QEMU_ARCH_ALL)
 135    Define an SGX EPC section.
 138DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
 139    "-cpu cpu        select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
 141``-cpu model``
 142    Select CPU model (``-cpu help`` for list and additional feature
 143    selection)
 146DEF("accel", HAS_ARG, QEMU_OPTION_accel,
 147    "-accel [accel=]accelerator[,prop[=value][,...]]\n"
 148    "                select accelerator (kvm, xen, hax, hvf, nvmm, whpx or tcg; use 'help' for a list)\n"
 149    "                igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
 150    "                kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
 151    "                kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
 152    "                split-wx=on|off (enable TCG split w^x mapping)\n"
 153    "                tb-size=n (TCG translation block cache size)\n"
 154    "                dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n"
 155    "                thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
 157``-accel name[,prop=value[,...]]``
 158    This is used to enable an accelerator. Depending on the target
 159    architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available. By
 160    default, tcg is used. If there is more than one accelerator
 161    specified, the next one is used if the previous one fails to
 162    initialize.
 164    ``igd-passthru=on|off``
 165        When Xen is in use, this option controls whether Intel
 166        integrated graphics devices can be passed through to the guest
 167        (default=off)
 169    ``kernel-irqchip=on|off|split``
 170        Controls KVM in-kernel irqchip support. The default is full
 171        acceleration of the interrupt controllers. On x86, split irqchip
 172        reduces the kernel attack surface, at a performance cost for
 173        non-MSI interrupts. Disabling the in-kernel irqchip completely
 174        is not recommended except for debugging purposes.
 176    ``kvm-shadow-mem=size``
 177        Defines the size of the KVM shadow MMU.
 179    ``split-wx=on|off``
 180        Controls the use of split w^x mapping for the TCG code generation
 181        buffer. Some operating systems require this to be enabled, and in
 182        such a case this will default on. On other operating systems, this
 183        will default off, but one may enable this for testing or debugging.
 185    ``tb-size=n``
 186        Controls the size (in MiB) of the TCG translation block cache.
 188    ``thread=single|multi``
 189        Controls number of TCG threads. When the TCG is multi-threaded
 190        there will be one thread per vCPU therefore taking advantage of
 191        additional host cores. The default is to enable multi-threading
 192        where both the back-end and front-ends support it and no
 193        incompatible TCG features have been enabled (e.g.
 194        icount/replay).
 196    ``dirty-ring-size=n``
 197        When the KVM accelerator is used, it controls the size of the per-vCPU
 198        dirty page ring buffer (number of entries for each vCPU). It should
 199        be a value that is power of two, and it should be 1024 or bigger (but
 200        still less than the maximum value that the kernel supports).  4096
 201        could be a good initial value if you have no idea which is the best.
 202        Set this value to 0 to disable the feature.  By default, this feature
 203        is disabled (dirty-ring-size=0).  When enabled, KVM will instead
 204        record dirty pages in a bitmap.
 208DEF("smp", HAS_ARG, QEMU_OPTION_smp,
 209    "-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,cores=cores][,threads=threads]\n"
 210    "                set the number of CPUs to 'n' [default=1]\n"
 211    "                maxcpus= maximum number of total CPUs, including\n"
 212    "                offline CPUs for hotplug, etc\n"
 213    "                sockets= number of discrete sockets in the system\n"
 214    "                dies= number of CPU dies on one socket (for PC only)\n"
 215    "                cores= number of CPU cores on one socket (for PC, it's on one die)\n"
 216    "                threads= number of threads on one CPU core\n",
 217        QEMU_ARCH_ALL)
 219``-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,cores=cores][,threads=threads]``
 220    Simulate a SMP system with '\ ``n``\ ' CPUs initially present on
 221    the machine type board. On boards supporting CPU hotplug, the optional
 222    '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be
 223    added at runtime. When both parameters are omitted, the maximum number
 224    of CPUs will be calculated from the provided topology members and the
 225    initial CPU count will match the maximum number. When only one of them
 226    is given then the omitted one will be set to its counterpart's value.
 227    Both parameters may be specified, but the maximum number of CPUs must
 228    be equal to or greater than the initial CPU count. Both parameters are
 229    subject to an upper limit that is determined by the specific machine
 230    type chosen.
 232    To control reporting of CPU topology information, the number of sockets,
 233    dies per socket, cores per die, and threads per core can be specified.
 234    The sum `` sockets * cores * dies * threads `` must be equal to the
 235    maximum CPU count. CPU targets may only support a subset of the topology
 236    parameters. Where a CPU target does not support use of a particular
 237    topology parameter, its value should be assumed to be 1 for the purpose
 238    of computing the CPU maximum count.
 240    Either the initial CPU count, or at least one of the topology parameters
 241    must be specified. The specified parameters must be greater than zero,
 242    explicit configuration like "cpus=0" is not allowed. Values for any
 243    omitted parameters will be computed from those which are given.
 244    Historically preference was given to the coarsest topology parameters
 245    when computing missing values (ie sockets preferred over cores, which
 246    were preferred over threads), however, this behaviour is considered
 247    liable to change. Prior to 6.2 the preference was sockets over cores
 248    over threads. Since 6.2 the preference is cores over sockets over threads.
 251DEF("numa", HAS_ARG, QEMU_OPTION_numa,
 252    "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
 253    "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
 254    "-numa dist,src=source,dst=destination,val=distance\n"
 255    "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
 256    "-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"
 257    "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
 258    QEMU_ARCH_ALL)
 260``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
 261  \ 
 262``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
 263  \
 264``-numa dist,src=source,dst=destination,val=distance``
 265  \ 
 266``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]``
 267  \ 
 268``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]``
 269  \ 
 270``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]``
 271    Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA
 272    distance from a source node to a destination node. Set the ACPI
 273    Heterogeneous Memory Attributes for the given nodes.
 275    Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and
 276    lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a
 277    contiguous range of CPU indexes (or a single VCPU if lastcpu is
 278    omitted). A non-contiguous set of VCPUs can be represented by
 279    providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is
 280    omitted on all nodes, VCPUs are automatically split between them.
 282    For example, the following option assigns VCPUs 0, 1, 2 and 5 to a
 283    NUMA node:
 285    ::
 287        -numa node,cpus=0-2,cpus=5
 289    '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option
 290    which uses '\ ``socket-id|core-id|thread-id``\ ' properties to
 291    assign CPU objects to a node using topology layout properties of
 292    CPU. The set of properties is machine specific, and depends on used
 293    machine type/'\ ``smp``\ ' options. It could be queried with
 294    '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ '
 295    property specifies node to which CPU object will be assigned, it's
 296    required for node to be declared with '\ ``node``\ ' option before
 297    it's used with '\ ``cpu``\ ' option.
 299    For example:
 301    ::
 303        -M pc \
 304        -smp 1,sockets=2,maxcpus=2 \
 305        -numa node,nodeid=0 -numa node,nodeid=1 \
 306        -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
 308    Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported
 309    for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from
 310    a given memory backend device to a node. If '\ ``mem``\ ' and
 311    '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them.
 314    '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive.
 315    Furthermore, if one node uses '\ ``memdev``\ ', all of them have to
 316    use it.
 318    '\ ``initiator``\ ' is an additional option that points to an
 319    initiator NUMA node that has best performance (the lowest latency or
 320    largest bandwidth) to this NUMA node. Note that this option can be
 321    set only when the machine property 'hmat' is set to 'on'.
 323    Following example creates a machine with 2 NUMA nodes, node 0 has
 324    CPU. node 1 has only memory, and its initiator is node 0. Note that
 325    because node 0 has CPU, by default the initiator of node 0 is itself
 326    and must be itself.
 328    ::
 330        -machine hmat=on \
 331        -m 2G,slots=2,maxmem=4G \
 332        -object memory-backend-ram,size=1G,id=m0 \
 333        -object memory-backend-ram,size=1G,id=m1 \
 334        -numa node,nodeid=0,memdev=m0 \
 335        -numa node,nodeid=1,memdev=m1,initiator=0 \
 336        -smp 2,sockets=2,maxcpus=2  \
 337        -numa cpu,node-id=0,socket-id=0 \
 338        -numa cpu,node-id=0,socket-id=1
 340    source and destination are NUMA node IDs. distance is the NUMA
 341    distance from source to destination. The distance from a node to
 342    itself is always 10. If any pair of nodes is given a distance, then
 343    all pairs must be given distances. Although, when distances are only
 344    given in one direction for each pair of nodes, then the distances in
 345    the opposite directions are assumed to be the same. If, however, an
 346    asymmetrical pair of distances is given for even one node pair, then
 347    all node pairs must be provided distance values for both directions,
 348    even when they are symmetrical. When a node is unreachable from
 349    another node, set the pair's distance to 255.
 351    Note that the -``numa`` option doesn't allocate any of the specified
 352    resources, it just assigns existing resources to NUMA nodes. This
 353    means that one still has to use the ``-m``, ``-smp`` options to
 354    allocate RAM and VCPUs respectively.
 356    Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
 357    Information between initiator and target NUMA nodes in ACPI
 358    Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can
 359    create memory requests, usually it has one or more processors.
 360    Target NUMA node contains addressable memory.
 362    In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is
 363    the memory hierarchy of the target NUMA node: if hierarchy is
 364    'memory', the structure represents the memory performance; if
 365    hierarchy is 'first-level\|second-level\|third-level', this
 366    structure represents aggregated performance of memory side caches
 367    for each domain. type of 'data-type' is type of data represented by
 368    this structure instance: if 'hierarchy' is 'memory', 'data-type' is
 369    'access\|read\|write' latency or 'access\|read\|write' bandwidth of
 370    the target memory; if 'hierarchy' is
 371    'first-level\|second-level\|third-level', 'data-type' is
 372    'access\|read\|write' hit latency or 'access\|read\|write' hit
 373    bandwidth of the target memory side cache.
 375    lat is latency value in nanoseconds. bw is bandwidth value, the
 376    possible value and units are NUM[M\|G\|T], mean that the bandwidth
 377    value are NUM byte per second (or MB/s, GB/s or TB/s depending on
 378    used suffix). Note that if latency or bandwidth value is 0, means
 379    the corresponding latency or bandwidth information is not provided.
 381    In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory
 382    belongs. size is the size of memory side cache in bytes. level is
 383    the cache level described in this structure, note that the cache
 384    level 0 should not be used with '\ ``hmat-cache``\ ' option.
 385    associativity is the cache associativity, the possible value is
 386    'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
 387    is the write policy. line is the cache Line size in bytes.
 389    For example, the following options describe 2 NUMA nodes. Node 0 has
 390    2 cpus and a ram, node 1 has only a ram. The processors in node 0
 391    access memory in node 0 with access-latency 5 nanoseconds,
 392    access-bandwidth is 200 MB/s; The processors in NUMA node 0 access
 393    memory in NUMA node 1 with access-latency 10 nanoseconds,
 394    access-bandwidth is 100 MB/s. And for memory side cache information,
 395    NUMA node 0 and 1 both have 1 level memory cache, size is 10KB,
 396    policy is write-back, the cache Line size is 8 bytes:
 398    ::
 400        -machine hmat=on \
 401        -m 2G \
 402        -object memory-backend-ram,size=1G,id=m0 \
 403        -object memory-backend-ram,size=1G,id=m1 \
 404        -smp 2,sockets=2,maxcpus=2 \
 405        -numa node,nodeid=0,memdev=m0 \
 406        -numa node,nodeid=1,memdev=m1,initiator=0 \
 407        -numa cpu,node-id=0,socket-id=0 \
 408        -numa cpu,node-id=0,socket-id=1 \
 409        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
 410        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
 411        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
 412        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
 413        -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
 414        -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
 417DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
 418    "-add-fd fd=fd,set=set[,opaque=opaque]\n"
 419    "                Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
 421``-add-fd fd=fd,set=set[,opaque=opaque]``
 422    Add a file descriptor to an fd set. Valid options are:
 424    ``fd=fd``
 425        This option defines the file descriptor of which a duplicate is
 426        added to fd set. The file descriptor cannot be stdin, stdout, or
 427        stderr.
 429    ``set=set``
 430        This option defines the ID of the fd set to add the file
 431        descriptor to.
 433    ``opaque=opaque``
 434        This option defines a free-form string that can be used to
 435        describe fd.
 437    You can open an image using pre-opened file descriptors from an fd
 438    set:
 440    .. parsed-literal::
 442        |qemu_system| \\
 443         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
 444         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
 445         -drive file=/dev/fdset/2,index=0,media=disk
 448DEF("set", HAS_ARG, QEMU_OPTION_set,
 449    "-set group.id.arg=value\n"
 450    "                set <arg> parameter for item <id> of type <group>\n"
 451    "                i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
 453``-set group.id.arg=value``
 454    Set parameter arg for item id of type group
 457DEF("global", HAS_ARG, QEMU_OPTION_global,
 458    "-global driver.property=value\n"
 459    "-global driver=driver,property=property,value=value\n"
 460    "                set a global default for a driver property\n",
 461    QEMU_ARCH_ALL)
 463``-global driver.prop=value``
 464  \ 
 465``-global driver=driver,property=property,value=value``
 466    Set default value of driver's property prop to value, e.g.:
 468    .. parsed-literal::
 470        |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img
 472    In particular, you can use this to set driver properties for devices
 473    which are created automatically by the machine model. To create a
 474    device which is not created automatically and set properties on it,
 475    use -``device``.
 477    -global driver.prop=value is shorthand for -global
 478    driver=driver,property=prop,value=value. The longhand syntax works
 479    even when driver contains a dot.
 482DEF("boot", HAS_ARG, QEMU_OPTION_boot,
 483    "-boot [order=drives][,once=drives][,menu=on|off]\n"
 484    "      [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
 485    "                'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
 486    "                'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
 487    "                'sp_time': the period that splash picture last if menu=on, unit is ms\n"
 488    "                'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
 489    QEMU_ARCH_ALL)
 491``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
 492    Specify boot order drives as a string of drive letters. Valid drive
 493    letters depend on the target architecture. The x86 PC uses: a, b
 494    (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
 495    (Etherboot from network adapter 1-4), hard disk boot is the default.
 496    To apply a particular boot order only on the first startup, specify
 497    it via ``once``. Note that the ``order`` or ``once`` parameter
 498    should not be used together with the ``bootindex`` property of
 499    devices, since the firmware implementations normally do not support
 500    both at the same time.
 502    Interactive boot menus/prompts can be enabled via ``menu=on`` as far
 503    as firmware/BIOS supports them. The default is non-interactive boot.
 505    A splash picture could be passed to bios, enabling user to show it
 506    as logo, when option splash=sp\_name is given and menu=on, If
 507    firmware/BIOS supports them. Currently Seabios for X86 system
 508    support it. limitation: The splash file could be a jpeg file or a
 509    BMP file in 24 BPP format(true color). The resolution should be
 510    supported by the SVGA mode, so the recommended is 320x240, 640x480,
 511    800x640.
 513    A timeout could be passed to bios, guest will pause for rb\_timeout
 514    ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
 515    not reboot, qemu passes '-1' to bios by default. Currently Seabios
 516    for X86 system support it.
 518    Do strict boot via ``strict=on`` as far as firmware/BIOS supports
 519    it. This only effects when boot priority is changed by bootindex
 520    options. The default is non-strict boot.
 522    .. parsed-literal::
 524        # try to boot from network first, then from hard disk
 525        |qemu_system_x86| -boot order=nc
 526        # boot from CD-ROM first, switch back to default order after reboot
 527        |qemu_system_x86| -boot once=d
 528        # boot with a splash picture for 5 seconds.
 529        |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000
 531    Note: The legacy format '-boot drives' is still supported but its
 532    use is discouraged as it may be removed from future versions.
 536    "-m [size=]megs[,slots=n,maxmem=size]\n"
 537    "                configure guest RAM\n"
 538    "                size: initial amount of guest memory\n"
 539    "                slots: number of hotplug slots (default: none)\n"
 540    "                maxmem: maximum amount of guest memory (default: none)\n"
 541    "NOTE: Some architectures might enforce a specific granularity\n",
 542    QEMU_ARCH_ALL)
 544``-m [size=]megs[,slots=n,maxmem=size]``
 545    Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
 546    Optionally, a suffix of "M" or "G" can be used to signify a value in
 547    megabytes or gigabytes respectively. Optional pair slots, maxmem
 548    could be used to set amount of hotpluggable memory slots and maximum
 549    amount of memory. Note that maxmem must be aligned to the page size.
 551    For example, the following command-line sets the guest startup RAM
 552    size to 1GB, creates 3 slots to hotplug additional memory and sets
 553    the maximum memory the guest can reach to 4GB:
 555    .. parsed-literal::
 557        |qemu_system| -m 1G,slots=3,maxmem=4G
 559    If slots and maxmem are not specified, memory hotplug won't be
 560    enabled and the guest startup RAM will never increase.
 563DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
 564    "-mem-path FILE  provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
 566``-mem-path path``
 567    Allocate guest RAM from a temporarily created file in path.
 570DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
 571    "-mem-prealloc   preallocate guest memory (use with -mem-path)\n",
 572    QEMU_ARCH_ALL)
 575    Preallocate memory when using -mem-path.
 579    "-k language     use keyboard layout (for example 'fr' for French)\n",
 580    QEMU_ARCH_ALL)
 582``-k language``
 583    Use keyboard layout language (for example ``fr`` for French). This
 584    option is only needed where it is not easy to get raw PC keycodes
 585    (e.g. on Macs, with some X11 servers or with a VNC or curses
 586    display). You don't normally need to use it on PC/Linux or
 587    PC/Windows hosts.
 589    The available layouts are:
 591    ::
 593        ar  de-ch  es  fo     fr-ca  hu  ja  mk     no  pt-br  sv
 594        da  en-gb  et  fr     fr-ch  is  lt  nl     pl  ru     th
 595        de  en-us  fi  fr-be  hr     it  lv  nl-be  pt  sl     tr
 597    The default is ``en-us``.
 601HXCOMM Deprecated by -audiodev
 602DEF("audio-help", 0, QEMU_OPTION_audio_help,
 603    "-audio-help     show -audiodev equivalent of the currently specified audio settings\n",
 604    QEMU_ARCH_ALL)
 607    Will show the -audiodev equivalent of the currently specified
 608    (deprecated) environment variables.
 611DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
 612    "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
 613    "                specifies the audio backend to use\n"
 614    "                id= identifier of the backend\n"
 615    "                timer-period= timer period in microseconds\n"
 616    "                in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
 617    "                in|out.fixed-settings= use fixed settings for host audio\n"
 618    "                in|out.frequency= frequency to use with fixed settings\n"
 619    "                in|out.channels= number of channels to use with fixed settings\n"
 620    "                in|out.format= sample format to use with fixed settings\n"
 621    "                valid values: s8, s16, s32, u8, u16, u32, f32\n"
 622    "                in|out.voices= number of voices to use\n"
 623    "                in|out.buffer-length= length of buffer in microseconds\n"
 624    "-audiodev none,id=id,[,prop[=value][,...]]\n"
 625    "                dummy driver that discards all output\n"
 627    "-audiodev alsa,id=id[,prop[=value][,...]]\n"
 628    "                in|out.dev= name of the audio device to use\n"
 629    "                in|out.period-length= length of period in microseconds\n"
 630    "                in|out.try-poll= attempt to use poll mode\n"
 631    "                threshold= threshold (in microseconds) when playback starts\n"
 634    "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
 635    "                in|out.buffer-count= number of buffers\n"
 638    "-audiodev dsound,id=id[,prop[=value][,...]]\n"
 639    "                latency= add extra latency to playback in microseconds\n"
 642    "-audiodev oss,id=id[,prop[=value][,...]]\n"
 643    "                in|out.dev= path of the audio device to use\n"
 644    "                in|out.buffer-count= number of buffers\n"
 645    "                in|out.try-poll= attempt to use poll mode\n"
 646    "                try-mmap= try using memory mapped access\n"
 647    "                exclusive= open device in exclusive mode\n"
 648    "                dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
 650#ifdef CONFIG_AUDIO_PA
 651    "-audiodev pa,id=id[,prop[=value][,...]]\n"
 652    "                server= PulseAudio server address\n"
 653    "                in|out.name= source/sink device name\n"
 654    "                in|out.latency= desired latency in microseconds\n"
 657    "-audiodev sdl,id=id[,prop[=value][,...]]\n"
 658    "                in|out.buffer-count= number of buffers\n"
 660#ifdef CONFIG_SPICE
 661    "-audiodev spice,id=id[,prop[=value][,...]]\n"
 663    "-audiodev wav,id=id[,prop[=value][,...]]\n"
 664    "                path= path of wav file to record\n",
 665    QEMU_ARCH_ALL)
 667``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
 668    Adds a new audio backend driver identified by id. There are global
 669    and driver specific properties. Some values can be set differently
 670    for input and output, they're marked with ``in|out.``. You can set
 671    the input's property with ``in.prop`` and the output's property with
 672    ``out.prop``. For example:
 674    ::
 676        -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
 677        -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
 679    NOTE: parameter validation is known to be incomplete, in many cases
 680    specifying an invalid option causes QEMU to print an error message
 681    and continue emulation without sound.
 683    Valid global options are:
 685    ``id=identifier``
 686        Identifies the audio backend.
 688    ``timer-period=period``
 689        Sets the timer period used by the audio subsystem in
 690        microseconds. Default is 10000 (10 ms).
 692    ``in|out.mixing-engine=on|off``
 693        Use QEMU's mixing engine to mix all streams inside QEMU and
 694        convert audio formats when not supported by the backend. When
 695        off, fixed-settings must be off too. Note that disabling this
 696        option means that the selected backend must support multiple
 697        streams and the audio formats used by the virtual cards,
 698        otherwise you'll get no sound. It's not recommended to disable
 699        this option unless you want to use 5.1 or 7.1 audio, as mixing
 700        engine only supports mono and stereo audio. Default is on.
 702    ``in|out.fixed-settings=on|off``
 703        Use fixed settings for host audio. When off, it will change
 704        based on how the guest opens the sound card. In this case you
 705        must not specify frequency, channels or format. Default is on.
 707    ``in|out.frequency=frequency``
 708        Specify the frequency to use when using fixed-settings. Default
 709        is 44100Hz.
 711    ``in|out.channels=channels``
 712        Specify the number of channels to use when using fixed-settings.
 713        Default is 2 (stereo).
 715    ``in|out.format=format``
 716        Specify the sample format to use when using fixed-settings.
 717        Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
 718        ``u32``, ``f32``. Default is ``s16``.
 720    ``in|out.voices=voices``
 721        Specify the number of voices to use. Default is 1.
 723    ``in|out.buffer-length=usecs``
 724        Sets the size of the buffer in microseconds.
 726``-audiodev none,id=id[,prop[=value][,...]]``
 727    Creates a dummy backend that discards all outputs. This backend has
 728    no backend specific properties.
 730``-audiodev alsa,id=id[,prop[=value][,...]]``
 731    Creates backend using the ALSA. This backend is only available on
 732    Linux.
 734    ALSA specific options are:
 736    ``in|out.dev=device``
 737        Specify the ALSA device to use for input and/or output. Default
 738        is ``default``.
 740    ``in|out.period-length=usecs``
 741        Sets the period length in microseconds.
 743    ``in|out.try-poll=on|off``
 744        Attempt to use poll mode with the device. Default is on.
 746    ``threshold=threshold``
 747        Threshold (in microseconds) when playback starts. Default is 0.
 749``-audiodev coreaudio,id=id[,prop[=value][,...]]``
 750    Creates a backend using Apple's Core Audio. This backend is only
 751    available on Mac OS and only supports playback.
 753    Core Audio specific options are:
 755    ``in|out.buffer-count=count``
 756        Sets the count of the buffers.
 758``-audiodev dsound,id=id[,prop[=value][,...]]``
 759    Creates a backend using Microsoft's DirectSound. This backend is
 760    only available on Windows and only supports playback.
 762    DirectSound specific options are:
 764    ``latency=usecs``
 765        Add extra usecs microseconds latency to playback. Default is
 766        10000 (10 ms).
 768``-audiodev oss,id=id[,prop[=value][,...]]``
 769    Creates a backend using OSS. This backend is available on most
 770    Unix-like systems.
 772    OSS specific options are:
 774    ``in|out.dev=device``
 775        Specify the file name of the OSS device to use. Default is
 776        ``/dev/dsp``.
 778    ``in|out.buffer-count=count``
 779        Sets the count of the buffers.
 781    ``in|out.try-poll=on|of``
 782        Attempt to use poll mode with the device. Default is on.
 784    ``try-mmap=on|off``
 785        Try using memory mapped device access. Default is off.
 787    ``exclusive=on|off``
 788        Open the device in exclusive mode (vmix won't work in this
 789        case). Default is off.
 791    ``dsp-policy=policy``
 792        Sets the timing policy (between 0 and 10, where smaller number
 793        means smaller latency but higher CPU usage). Use -1 to use
 794        buffer sizes specified by ``buffer`` and ``buffer-count``. This
 795        option is ignored if you do not have OSS 4. Default is 5.
 797``-audiodev pa,id=id[,prop[=value][,...]]``
 798    Creates a backend using PulseAudio. This backend is available on
 799    most systems.
 801    PulseAudio specific options are:
 803    ``server=server``
 804        Sets the PulseAudio server to connect to.
 806    ``in|out.name=sink``
 807        Use the specified source/sink for recording/playback.
 809    ``in|out.latency=usecs``
 810        Desired latency in microseconds. The PulseAudio server will try
 811        to honor this value but actual latencies may be lower or higher.
 813``-audiodev sdl,id=id[,prop[=value][,...]]``
 814    Creates a backend using SDL. This backend is available on most
 815    systems, but you should use your platform's native backend if
 816    possible.
 818    SDL specific options are:
 820    ``in|out.buffer-count=count``
 821        Sets the count of the buffers.
 823``-audiodev spice,id=id[,prop[=value][,...]]``
 824    Creates a backend that sends audio through SPICE. This backend
 825    requires ``-spice`` and automatically selected in that case, so
 826    usually you can ignore this option. This backend has no backend
 827    specific properties.
 829``-audiodev wav,id=id[,prop[=value][,...]]``
 830    Creates a backend that writes audio to a WAV file.
 832    Backend specific options are:
 834    ``path=path``
 835        Write recorded audio into the specified file. Default is
 836        ``qemu.wav``.
 839DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
 840    "-soundhw c1,... enable audio support\n"
 841    "                and only specified sound cards (comma separated list)\n"
 842    "                use '-soundhw help' to get the list of supported cards\n"
 843    "                use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
 845``-soundhw card1[,card2,...] or -soundhw all``
 846    Enable audio and selected sound hardware. Use 'help' to print all
 847    available sound hardware. For example:
 849    .. parsed-literal::
 851        |qemu_system_x86| -soundhw sb16,adlib disk.img
 852        |qemu_system_x86| -soundhw es1370 disk.img
 853        |qemu_system_x86| -soundhw ac97 disk.img
 854        |qemu_system_x86| -soundhw hda disk.img
 855        |qemu_system_x86| -soundhw all disk.img
 856        |qemu_system_x86| -soundhw help
 858    Note that Linux's i810\_audio OSS kernel (for AC97) module might
 859    require manually specifying clocking.
 861    ::
 863        modprobe i810_audio clocking=48000
 866DEF("device", HAS_ARG, QEMU_OPTION_device,
 867    "-device driver[,prop[=value][,...]]\n"
 868    "                add device (based on driver)\n"
 869    "                prop=value,... sets driver properties\n"
 870    "                use '-device help' to print all possible drivers\n"
 871    "                use '-device driver,help' to print all possible properties\n",
 872    QEMU_ARCH_ALL)
 874``-device driver[,prop[=value][,...]]``
 875    Add device driver. prop=value sets driver properties. Valid
 876    properties depend on the driver. To get help on possible drivers and
 877    properties, use ``-device help`` and ``-device driver,help``.
 879    Some drivers are:
 881``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]``
 882    Add an IPMI BMC. This is a simulation of a hardware management
 883    interface processor that normally sits on a system. It provides a
 884    watchdog and the ability to reset and power control the system. You
 885    need to connect this to an IPMI interface to make it useful
 887    The IPMI slave address to use for the BMC. The default is 0x20. This
 888    address is the BMC's address on the I2C network of management
 889    controllers. If you don't know what this means, it is safe to ignore
 890    it.
 892    ``id=id``
 893        The BMC id for interfaces to use this device.
 895    ``slave_addr=val``
 896        Define slave address to use for the BMC. The default is 0x20.
 898    ``sdrfile=file``
 899        file containing raw Sensor Data Records (SDR) data. The default
 900        is none.
 902    ``fruareasize=val``
 903        size of a Field Replaceable Unit (FRU) area. The default is
 904        1024.
 906    ``frudatafile=file``
 907        file containing raw Field Replaceable Unit (FRU) inventory data.
 908        The default is none.
 910    ``guid=uuid``
 911        value for the GUID for the BMC, in standard UUID format. If this
 912        is set, get "Get GUID" command to the BMC will return it.
 913        Otherwise "Get GUID" will return an error.
 915``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
 916    Add a connection to an external IPMI BMC simulator. Instead of
 917    locally emulating the BMC like the above item, instead connect to an
 918    external entity that provides the IPMI services.
 920    A connection is made to an external BMC simulator. If you do this,
 921    it is strongly recommended that you use the "reconnect=" chardev
 922    option to reconnect to the simulator if the connection is lost. Note
 923    that if this is not used carefully, it can be a security issue, as
 924    the interface has the ability to send resets, NMIs, and power off
 925    the VM. It's best if QEMU makes a connection to an external
 926    simulator running on a secure port on localhost, so neither the
 927    simulator nor QEMU is exposed to any outside network.
 929    See the "lanserv/README.vm" file in the OpenIPMI library for more
 930    details on the external interface.
 932``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
 933    Add a KCS IPMI interafce on the ISA bus. This also adds a
 934    corresponding ACPI and SMBIOS entries, if appropriate.
 936    ``bmc=id``
 937        The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
 938        above.
 940    ``ioport=val``
 941        Define the I/O address of the interface. The default is 0xca0
 942        for KCS.
 944    ``irq=val``
 945        Define the interrupt to use. The default is 5. To disable
 946        interrupts, set this to 0.
 948``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
 949    Like the KCS interface, but defines a BT interface. The default port
 950    is 0xe4 and the default interrupt is 5.
 952``-device pci-ipmi-kcs,bmc=id``
 953    Add a KCS IPMI interafce on the PCI bus.
 955    ``bmc=id``
 956        The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
 958``-device pci-ipmi-bt,bmc=id``
 959    Like the KCS interface, but defines a BT interface on the PCI bus.
 961``-device intel-iommu[,option=...]``
 962    This is only supported by ``-machine q35``, which will enable Intel VT-d
 963    emulation within the guest.  It supports below options:
 965    ``intremap=on|off`` (default: auto)
 966        This enables interrupt remapping feature.  It's required to enable
 967        complete x2apic.  Currently it only supports kvm kernel-irqchip modes
 968        ``off`` or ``split``, while full kernel-irqchip is not yet supported.
 969        The default value is "auto", which will be decided by the mode of
 970        kernel-irqchip.
 972    ``caching-mode=on|off`` (default: off)
 973        This enables caching mode for the VT-d emulated device.  When
 974        caching-mode is enabled, each guest DMA buffer mapping will generate an
 975        IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in
 976        a synchronous way.  It is required for ``-device vfio-pci`` to work
 977        with the VT-d device, because host assigned devices requires to setup
 978        the DMA mapping on the host before guest DMA starts.
 980    ``device-iotlb=on|off`` (default: off)
 981        This enables device-iotlb capability for the emulated VT-d device.  So
 982        far virtio/vhost should be the only real user for this parameter,
 983        paired with ats=on configured for the device.
 985    ``aw-bits=39|48`` (default: 39)
 986        This decides the address width of IOVA address space.  The address
 987        space has 39 bits width for 3-level IOMMU page tables, and 48 bits for
 988        4-level IOMMU page tables.
 990    Please also refer to the wiki page for general scenarios of VT-d
 991    emulation in QEMU: https://wiki.qemu.org/Features/VT-d.
 995DEF("name", HAS_ARG, QEMU_OPTION_name,
 996    "-name string1[,process=string2][,debug-threads=on|off]\n"
 997    "                set the name of the guest\n"
 998    "                string1 sets the window title and string2 the process name\n"
 999    "                When debug-threads is enabled, individual threads are given a separate name\n"
1000    "                NOTE: The thread names are for debugging and not a stable API.\n",
1001    QEMU_ARCH_ALL)
1003``-name name``
1004    Sets the name of the guest. This name will be displayed in the SDL
1005    window caption. The name will also be used for the VNC server. Also
1006    optionally set the top visible process name in Linux. Naming of
1007    individual threads can also be enabled on Linux to aid debugging.
1010DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
1011    "-uuid %08x-%04x-%04x-%04x-%012x\n"
1012    "                specify machine UUID\n", QEMU_ARCH_ALL)
1014``-uuid uuid``
1015    Set system UUID.
1020DEFHEADING(Block device options:)
1022DEF("fda", HAS_ARG, QEMU_OPTION_fda,
1023    "-fda/-fdb file  use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
1026``-fda file``
1027  \
1028``-fdb file``
1029    Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in
1030    the System Emulation Users Guide).
1033DEF("hda", HAS_ARG, QEMU_OPTION_hda,
1034    "-hda/-hdb file  use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL)
1036DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
1037    "-hdc/-hdd file  use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL)
1040``-hda file``
1041  \
1042``-hdb file``
1043  \ 
1044``-hdc file``
1045  \ 
1046``-hdd file``
1047    Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images`
1048    chapter in the System Emulation Users Guide).
1051DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
1052    "-cdrom file     use 'file' as IDE cdrom image (cdrom is ide1 master)\n",
1053    QEMU_ARCH_ALL)
1055``-cdrom file``
1056    Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at
1057    the same time). You can use the host CD-ROM by using ``/dev/cdrom``
1058    as filename.
1061DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
1062    "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
1063    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
1064    "          [,read-only=on|off][,auto-read-only=on|off]\n"
1065    "          [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
1066    "          [,driver specific parameters...]\n"
1067    "                configure a block backend\n", QEMU_ARCH_ALL)
1069``-blockdev option[,option[,option[,...]]]``
1070    Define a new block driver node. Some of the options apply to all
1071    block drivers, other options are only accepted for a specific block
1072    driver. See below for a list of generic options and options for the
1073    most common block drivers.
1075    Options that expect a reference to another node (e.g. ``file``) can
1076    be given in two ways. Either you specify the node name of an already
1077    existing node (file=node-name), or you define a new node inline,
1078    adding options for the referenced node after a dot
1079    (file.filename=path,file.aio=native).
1081    A block driver node created with ``-blockdev`` can be used for a
1082    guest device by specifying its node name for the ``drive`` property
1083    in a ``-device`` argument that defines a block device.
1085    ``Valid options for any block driver node:``
1086        ``driver``
1087            Specifies the block driver to use for the given node.
1089        ``node-name``
1090            This defines the name of the block driver node by which it
1091            will be referenced later. The name must be unique, i.e. it
1092            must not match the name of a different block driver node, or
1093            (if you use ``-drive`` as well) the ID of a drive.
1095            If no node name is specified, it is automatically generated.
1096            The generated node name is not intended to be predictable
1097            and changes between QEMU invocations. For the top level, an
1098            explicit node name must be specified.
1100        ``read-only``
1101            Open the node read-only. Guest write attempts will fail.
1103            Note that some block drivers support only read-only access,
1104            either generally or in certain configurations. In this case,
1105            the default value ``read-only=off`` does not work and the
1106            option must be specified explicitly.
1108        ``auto-read-only``
1109            If ``auto-read-only=on`` is set, QEMU may fall back to
1110            read-only usage even when ``read-only=off`` is requested, or
1111            even switch between modes as needed, e.g. depending on
1112            whether the image file is writable or whether a writing user
1113            is attached to the node.
1115        ``force-share``
1116            Override the image locking system of QEMU by forcing the
1117            node to utilize weaker shared access for permissions where
1118            it would normally request exclusive access. When there is
1119            the potential for multiple instances to have the same file
1120            open (whether this invocation of QEMU is the first or the
1121            second instance), both instances must permit shared access
1122            for the second instance to succeed at opening the file.
1124            Enabling ``force-share=on`` requires ``read-only=on``.
1126        ``cache.direct``
1127            The host page cache can be avoided with ``cache.direct=on``.
1128            This will attempt to do disk IO directly to the guest's
1129            memory. QEMU may still perform an internal copy of the data.
1131        ``cache.no-flush``
1132            In case you don't care about data integrity over host
1133            failures, you can use ``cache.no-flush=on``. This option
1134            tells QEMU that it never needs to write any data to the disk
1135            but can instead keep things in cache. If anything goes
1136            wrong, like your host losing power, the disk storage getting
1137            disconnected accidentally, etc. your image will most
1138            probably be rendered unusable.
1140        ``discard=discard``
1141            discard is one of "ignore" (or "off") or "unmap" (or "on")
1142            and controls whether ``discard`` (also known as ``trim`` or
1143            ``unmap``) requests are ignored or passed to the filesystem.
1144            Some machine types may not support discard requests.
1146        ``detect-zeroes=detect-zeroes``
1147            detect-zeroes is "off", "on" or "unmap" and enables the
1148            automatic conversion of plain zero writes by the OS to
1149            driver specific optimized zero write commands. You may even
1150            choose "unmap" if discard is set to "unmap" to allow a zero
1151            write to be converted to an ``unmap`` operation.
1153    ``Driver-specific options for file``
1154        This is the protocol-level block driver for accessing regular
1155        files.
1157        ``filename``
1158            The path to the image file in the local filesystem
1160        ``aio``
1161            Specifies the AIO backend (threads/native/io_uring,
1162            default: threads)
1164        ``locking``
1165            Specifies whether the image file is protected with Linux OFD
1166            / POSIX locks. The default is to use the Linux Open File
1167            Descriptor API if available, otherwise no lock is applied.
1168            (auto/on/off, default: auto)
1170        Example:
1172        ::
1174            -blockdev driver=file,node-name=disk,filename=disk.img
1176    ``Driver-specific options for raw``
1177        This is the image format block driver for raw images. It is
1178        usually stacked on top of a protocol level block driver such as
1179        ``file``.
1181        ``file``
1182            Reference to or definition of the data source block driver
1183            node (e.g. a ``file`` driver node)
1185        Example 1:
1187        ::
1189            -blockdev driver=file,node-name=disk_file,filename=disk.img
1190            -blockdev driver=raw,node-name=disk,file=disk_file
1192        Example 2:
1194        ::
1196            -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1198    ``Driver-specific options for qcow2``
1199        This is the image format block driver for qcow2 images. It is
1200        usually stacked on top of a protocol level block driver such as
1201        ``file``.
1203        ``file``
1204            Reference to or definition of the data source block driver
1205            node (e.g. a ``file`` driver node)
1207        ``backing``
1208            Reference to or definition of the backing file block device
1209            (default is taken from the image file). It is allowed to
1210            pass ``null`` here in order to disable the default backing
1211            file.
1213        ``lazy-refcounts``
1214            Whether to enable the lazy refcounts feature (on/off;
1215            default is taken from the image file)
1217        ``cache-size``
1218            The maximum total size of the L2 table and refcount block
1219            caches in bytes (default: the sum of l2-cache-size and
1220            refcount-cache-size)
1222        ``l2-cache-size``
1223            The maximum size of the L2 table cache in bytes (default: if
1224            cache-size is not specified - 32M on Linux platforms, and 8M
1225            on non-Linux platforms; otherwise, as large as possible
1226            within the cache-size, while permitting the requested or the
1227            minimal refcount cache size)
1229        ``refcount-cache-size``
1230            The maximum size of the refcount block cache in bytes
1231            (default: 4 times the cluster size; or if cache-size is
1232            specified, the part of it which is not used for the L2
1233            cache)
1235        ``cache-clean-interval``
1236            Clean unused entries in the L2 and refcount caches. The
1237            interval is in seconds. The default value is 600 on
1238            supporting platforms, and 0 on other platforms. Setting it
1239            to 0 disables this feature.
1241        ``pass-discard-request``
1242            Whether discard requests to the qcow2 device should be
1243            forwarded to the data source (on/off; default: on if
1244            discard=unmap is specified, off otherwise)
1246        ``pass-discard-snapshot``
1247            Whether discard requests for the data source should be
1248            issued when a snapshot operation (e.g. deleting a snapshot)
1249            frees clusters in the qcow2 file (on/off; default: on)
1251        ``pass-discard-other``
1252            Whether discard requests for the data source should be
1253            issued on other occasions where a cluster gets freed
1254            (on/off; default: off)
1256        ``overlap-check``
1257            Which overlap checks to perform for writes to the image
1258            (none/constant/cached/all; default: cached). For details or
1259            finer granularity control refer to the QAPI documentation of
1260            ``blockdev-add``.
1262        Example 1:
1264        ::
1266            -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1267            -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1269        Example 2:
1271        ::
1273            -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1275    ``Driver-specific options for other drivers``
1276        Please refer to the QAPI documentation of the ``blockdev-add``
1277        QMP command.
1280DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1281    "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1282    "       [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1283    "       [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1284    "       [,werror=ignore|stop|report|enospc][,id=name]\n"
1285    "       [,aio=threads|native|io_uring]\n"
1286    "       [,readonly=on|off][,copy-on-read=on|off]\n"
1287    "       [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1288    "       [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1289    "       [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1290    "       [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1291    "       [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1292    "       [[,iops_size=is]]\n"
1293    "       [[,group=g]]\n"
1294    "                use 'file' as a drive image\n", QEMU_ARCH_ALL)
1296``-drive option[,option[,option[,...]]]``
1297    Define a new drive. This includes creating a block driver node (the
1298    backend) as well as a guest device, and is mostly a shortcut for
1299    defining the corresponding ``-blockdev`` and ``-device`` options.
1301    ``-drive`` accepts all options that are accepted by ``-blockdev``.
1302    In addition, it knows the following options:
1304    ``file=file``
1305        This option defines which disk image (see the :ref:`disk images`
1306        chapter in the System Emulation Users Guide) to use with this drive.
1307        If the filename contains comma, you must double it (for instance,
1308        "file=my,,file" to use file "my,file").
1310        Special files such as iSCSI devices can be specified using
1311        protocol specific URLs. See the section for "Device URL Syntax"
1312        for more information.
1314    ``if=interface``
1315        This option defines on which type on interface the drive is
1316        connected. Available types are: ide, scsi, sd, mtd, floppy,
1317        pflash, virtio, none.
1319    ``bus=bus,unit=unit``
1320        These options define where is connected the drive by defining
1321        the bus number and the unit id.
1323    ``index=index``
1324        This option defines where is connected the drive by using an
1325        index in the list of available connectors of a given interface
1326        type.
1328    ``media=media``
1329        This option defines the type of the media: disk or cdrom.
1331    ``snapshot=snapshot``
1332        snapshot is "on" or "off" and controls snapshot mode for the
1333        given drive (see ``-snapshot``).
1335    ``cache=cache``
1336        cache is "none", "writeback", "unsafe", "directsync" or
1337        "writethrough" and controls how the host cache is used to access
1338        block data. This is a shortcut that sets the ``cache.direct``
1339        and ``cache.no-flush`` options (as in ``-blockdev``), and
1340        additionally ``cache.writeback``, which provides a default for
1341        the ``write-cache`` option of block guest devices (as in
1342        ``-device``). The modes correspond to the following settings:
1344        =============  ===============   ============   ==============
1345        \              cache.writeback   cache.direct   cache.no-flush
1346        =============  ===============   ============   ==============
1347        writeback      on                off            off
1348        none           on                on             off
1349        writethrough   off               off            off
1350        directsync     off               on             off
1351        unsafe         on                off            on
1352        =============  ===============   ============   ==============
1354        The default mode is ``cache=writeback``.
1356    ``aio=aio``
1357        aio is "threads", "native", or "io_uring" and selects between pthread
1358        based disk I/O, native Linux AIO, or Linux io_uring API.
1360    ``format=format``
1361        Specify which disk format will be used rather than detecting the
1362        format. Can be used to specify format=raw to avoid interpreting
1363        an untrusted format header.
1365    ``werror=action,rerror=action``
1366        Specify which action to take on write and read errors. Valid
1367        actions are: "ignore" (ignore the error and try to continue),
1368        "stop" (pause QEMU), "report" (report the error to the guest),
1369        "enospc" (pause QEMU only if the host disk is full; report the
1370        error to the guest otherwise). The default setting is
1371        ``werror=enospc`` and ``rerror=report``.
1373    ``copy-on-read=copy-on-read``
1374        copy-on-read is "on" or "off" and enables whether to copy read
1375        backing file sectors into the image file.
1377    ``bps=b,bps_rd=r,bps_wr=w``
1378        Specify bandwidth throttling limits in bytes per second, either
1379        for all request types or for reads or writes only. Small values
1380        can lead to timeouts or hangs inside the guest. A safe minimum
1381        for disks is 2 MB/s.
1383    ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
1384        Specify bursts in bytes per second, either for all request types
1385        or for reads or writes only. Bursts allow the guest I/O to spike
1386        above the limit temporarily.
1388    ``iops=i,iops_rd=r,iops_wr=w``
1389        Specify request rate limits in requests per second, either for
1390        all request types or for reads or writes only.
1392    ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
1393        Specify bursts in requests per second, either for all request
1394        types or for reads or writes only. Bursts allow the guest I/O to
1395        spike above the limit temporarily.
1397    ``iops_size=is``
1398        Let every is bytes of a request count as a new request for iops
1399        throttling purposes. Use this option to prevent guests from
1400        circumventing iops limits by sending fewer but larger requests.
1402    ``group=g``
1403        Join a throttling quota group with given name g. All drives that
1404        are members of the same group are accounted for together. Use
1405        this option to prevent guests from circumventing throttling
1406        limits by using many small disks instead of a single larger
1407        disk.
1409    By default, the ``cache.writeback=on`` mode is used. It will report
1410    data writes as completed as soon as the data is present in the host
1411    page cache. This is safe as long as your guest OS makes sure to
1412    correctly flush disk caches where needed. If your guest OS does not
1413    handle volatile disk write caches correctly and your host crashes or
1414    loses power, then the guest may experience data corruption.
1416    For such guests, you should consider using ``cache.writeback=off``.
1417    This means that the host page cache will be used to read and write
1418    data, but write notification will be sent to the guest only after
1419    QEMU has made sure to flush each write to the disk. Be aware that
1420    this has a major impact on performance.
1422    When using the ``-snapshot`` option, unsafe caching is always used.
1424    Copy-on-read avoids accessing the same backing file sectors
1425    repeatedly and is useful when the backing file is over a slow
1426    network. By default copy-on-read is off.
1428    Instead of ``-cdrom`` you can use:
1430    .. parsed-literal::
1432        |qemu_system| -drive file=file,index=2,media=cdrom
1434    Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:
1436    .. parsed-literal::
1438        |qemu_system| -drive file=file,index=0,media=disk
1439        |qemu_system| -drive file=file,index=1,media=disk
1440        |qemu_system| -drive file=file,index=2,media=disk
1441        |qemu_system| -drive file=file,index=3,media=disk
1443    You can open an image using pre-opened file descriptors from an fd
1444    set:
1446    .. parsed-literal::
1448        |qemu_system| \\
1449         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
1450         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
1451         -drive file=/dev/fdset/2,index=0,media=disk
1453    You can connect a CDROM to the slave of ide0:
1455    .. parsed-literal::
1457        |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom
1459    If you don't specify the "file=" argument, you define an empty
1460    drive:
1462    .. parsed-literal::
1464        |qemu_system_x86| -drive if=ide,index=1,media=cdrom
1466    Instead of ``-fda``, ``-fdb``, you can use:
1468    .. parsed-literal::
1470        |qemu_system_x86| -drive file=file,index=0,if=floppy
1471        |qemu_system_x86| -drive file=file,index=1,if=floppy
1473    By default, interface is "ide" and index is automatically
1474    incremented:
1476    .. parsed-literal::
1478        |qemu_system_x86| -drive file=a -drive file=b"
1480    is interpreted like:
1482    .. parsed-literal::
1484        |qemu_system_x86| -hda a -hdb b
1487DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1488    "-mtdblock file  use 'file' as on-board Flash memory image\n",
1489    QEMU_ARCH_ALL)
1491``-mtdblock file``
1492    Use file as on-board Flash memory image.
1495DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1496    "-sd file        use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1498``-sd file``
1499    Use file as SecureDigital card image.
1502DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
1503    "-pflash file    use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
1505``-pflash file``
1506    Use file as a parallel flash image.
1509DEF("snapshot", 0, QEMU_OPTION_snapshot,
1510    "-snapshot       write to temporary files instead of disk image files\n",
1511    QEMU_ARCH_ALL)
1514    Write to temporary files instead of disk image files. In this case,
1515    the raw disk image you use is not written back. You can however
1516    force the write back by pressing C-a s (see the :ref:`disk images`
1517    chapter in the System Emulation Users Guide).
1520DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1521    "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1522    " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n"
1523    " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1524    " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1525    " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1526    " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1527    " [[,throttling.iops-size=is]]\n"
1528    "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n"
1529    "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n"
1530    "-fsdev synth,id=id\n",
1531    QEMU_ARCH_ALL)
1534``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]``
1535  \ 
1536``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]``
1537  \
1538``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]``
1539  \
1540``-fsdev synth,id=id[,readonly=on]``
1541    Define a new file system device. Valid options are:
1543    ``local``
1544        Accesses to the filesystem are done by QEMU.
1546    ``proxy``
1547        Accesses to the filesystem are done by virtfs-proxy-helper(1).
1549    ``synth``
1550        Synthetic filesystem, only used by QTests.
1552    ``id=id``
1553        Specifies identifier for this device.
1555    ``path=path``
1556        Specifies the export path for the file system device. Files
1557        under this path will be available to the 9p client on the guest.
1559    ``security_model=security_model``
1560        Specifies the security model to be used for this export path.
1561        Supported security models are "passthrough", "mapped-xattr",
1562        "mapped-file" and "none". In "passthrough" security model, files
1563        are stored using the same credentials as they are created on the
1564        guest. This requires QEMU to run as root. In "mapped-xattr"
1565        security model, some of the file attributes like uid, gid, mode
1566        bits and link target are stored as file attributes. For
1567        "mapped-file" these attributes are stored in the hidden
1568        .virtfs\_metadata directory. Directories exported by this
1569        security model cannot interact with other unix tools. "none"
1570        security model is same as passthrough except the sever won't
1571        report failures if it fails to set file attributes like
1572        ownership. Security model is mandatory only for local fsdriver.
1573        Other fsdrivers (like proxy) don't take security model as a
1574        parameter.
1576    ``writeout=writeout``
1577        This is an optional argument. The only supported value is
1578        "immediate". This means that host page cache will be used to
1579        read and write data but write notification will be sent to the
1580        guest only when the data has been reported as written by the
1581        storage subsystem.
1583    ``readonly=on``
1584        Enables exporting 9p share as a readonly mount for guests. By
1585        default read-write access is given.
1587    ``socket=socket``
1588        Enables proxy filesystem driver to use passed socket file for
1589        communicating with virtfs-proxy-helper(1).
1591    ``sock_fd=sock_fd``
1592        Enables proxy filesystem driver to use passed socket descriptor
1593        for communicating with virtfs-proxy-helper(1). Usually a helper
1594        like libvirt will create socketpair and pass one of the fds as
1595        sock\_fd.
1597    ``fmode=fmode``
1598        Specifies the default mode for newly created files on the host.
1599        Works only with security models "mapped-xattr" and
1600        "mapped-file".
1602    ``dmode=dmode``
1603        Specifies the default mode for newly created directories on the
1604        host. Works only with security models "mapped-xattr" and
1605        "mapped-file".
1607    ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w``
1608        Specify bandwidth throttling limits in bytes per second, either
1609        for all request types or for reads or writes only.
1611    ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm``
1612        Specify bursts in bytes per second, either for all request types
1613        or for reads or writes only. Bursts allow the guest I/O to spike
1614        above the limit temporarily.
1616    ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w``
1617        Specify request rate limits in requests per second, either for
1618        all request types or for reads or writes only.
1620    ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm``
1621        Specify bursts in requests per second, either for all request
1622        types or for reads or writes only. Bursts allow the guest I/O to
1623        spike above the limit temporarily.
1625    ``throttling.iops-size=is``
1626        Let every is bytes of a request count as a new request for iops
1627        throttling purposes.
1629    -fsdev option is used along with -device driver "virtio-9p-...".
1631``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag``
1632    Options for virtio-9p-... driver are:
1634    ``type``
1635        Specifies the variant to be used. Supported values are "pci",
1636        "ccw" or "device", depending on the machine type.
1638    ``fsdev=id``
1639        Specifies the id value specified along with -fsdev option.
1641    ``mount_tag=mount_tag``
1642        Specifies the tag name to be used by the guest to mount this
1643        export point.
1646DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1647    "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1648    "        [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1649    "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n"
1650    "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n"
1651    "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n",
1652    QEMU_ARCH_ALL)
1655``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]``
1656  \ 
1657``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1658  \ 
1659``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1660  \
1661``-virtfs synth,mount_tag=mount_tag``
1662    Define a new virtual filesystem device and expose it to the guest using
1663    a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain
1664    directory on host is made directly accessible by guest as a pass-through
1665    file system by using the 9P network protocol for communication between
1666    host and guests, if desired even accessible, shared by several guests
1667    simultaniously.
1669    Note that ``-virtfs`` is actually just a convenience shortcut for its
1670    generalized form ``-fsdev -device virtio-9p-pci``.
1672    The general form of pass-through file system options are:
1674    ``local``
1675        Accesses to the filesystem are done by QEMU.
1677    ``proxy``
1678        Accesses to the filesystem are done by virtfs-proxy-helper(1).
1680    ``synth``
1681        Synthetic filesystem, only used by QTests.
1683    ``id=id``
1684        Specifies identifier for the filesystem device
1686    ``path=path``
1687        Specifies the export path for the file system device. Files
1688        under this path will be available to the 9p client on the guest.
1690    ``security_model=security_model``
1691        Specifies the security model to be used for this export path.
1692        Supported security models are "passthrough", "mapped-xattr",
1693        "mapped-file" and "none". In "passthrough" security model, files
1694        are stored using the same credentials as they are created on the
1695        guest. This requires QEMU to run as root. In "mapped-xattr"
1696        security model, some of the file attributes like uid, gid, mode
1697        bits and link target are stored as file attributes. For
1698        "mapped-file" these attributes are stored in the hidden
1699        .virtfs\_metadata directory. Directories exported by this
1700        security model cannot interact with other unix tools. "none"
1701        security model is same as passthrough except the sever won't
1702        report failures if it fails to set file attributes like
1703        ownership. Security model is mandatory only for local fsdriver.
1704        Other fsdrivers (like proxy) don't take security model as a
1705        parameter.
1707    ``writeout=writeout``
1708        This is an optional argument. The only supported value is
1709        "immediate". This means that host page cache will be used to
1710        read and write data but write notification will be sent to the
1711        guest only when the data has been reported as written by the
1712        storage subsystem.
1714    ``readonly=on``
1715        Enables exporting 9p share as a readonly mount for guests. By
1716        default read-write access is given.
1718    ``socket=socket``
1719        Enables proxy filesystem driver to use passed socket file for
1720        communicating with virtfs-proxy-helper(1). Usually a helper like
1721        libvirt will create socketpair and pass one of the fds as
1722        sock\_fd.
1724    ``sock_fd``
1725        Enables proxy filesystem driver to use passed 'sock\_fd' as the
1726        socket descriptor for interfacing with virtfs-proxy-helper(1).
1728    ``fmode=fmode``
1729        Specifies the default mode for newly created files on the host.
1730        Works only with security models "mapped-xattr" and
1731        "mapped-file".
1733    ``dmode=dmode``
1734        Specifies the default mode for newly created directories on the
1735        host. Works only with security models "mapped-xattr" and
1736        "mapped-file".
1738    ``mount_tag=mount_tag``
1739        Specifies the tag name to be used by the guest to mount this
1740        export point.
1742    ``multidevs=multidevs``
1743        Specifies how to deal with multiple devices being shared with a
1744        9p export. Supported behaviours are either "remap", "forbid" or
1745        "warn". The latter is the default behaviour on which virtfs 9p
1746        expects only one device to be shared with the same export, and
1747        if more than one device is shared and accessed via the same 9p
1748        export then only a warning message is logged (once) by qemu on
1749        host side. In order to avoid file ID collisions on guest you
1750        should either create a separate virtfs export for each device to
1751        be shared with guests (recommended way) or you might use "remap"
1752        instead which allows you to share multiple devices with only one
1753        export instead, which is achieved by remapping the original
1754        inode numbers from host to guest in a way that would prevent
1755        such collisions. Remapping inodes in such use cases is required
1756        because the original device IDs from host are never passed and
1757        exposed on guest. Instead all files of an export shared with
1758        virtfs always share the same device id on guest. So two files
1759        with identical inode numbers but from actually different devices
1760        on host would otherwise cause a file ID collision and hence
1761        potential misbehaviours on guest. "forbid" on the other hand
1762        assumes like "warn" that only one device is shared by the same
1763        export, however it will not only log a warning message but also
1764        deny access to additional devices on guest. Note though that
1765        "forbid" does currently not block all possible file access
1766        operations (e.g. readdir() would still return entries from other
1767        devices).
1770DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
1771    "-iscsi [user=user][,password=password]\n"
1772    "       [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
1773    "       [,initiator-name=initiator-iqn][,id=target-iqn]\n"
1774    "       [,timeout=timeout]\n"
1775    "                iSCSI session parameters\n", QEMU_ARCH_ALL)
1779    Configure iSCSI session parameters.
1784DEFHEADING(USB convenience options:)
1786DEF("usb", 0, QEMU_OPTION_usb,
1787    "-usb            enable on-board USB host controller (if not enabled by default)\n",
1788    QEMU_ARCH_ALL)
1791    Enable USB emulation on machine types with an on-board USB host
1792    controller (if not enabled by default). Note that on-board USB host
1793    controllers may not support USB 3.0. In this case
1794    ``-device qemu-xhci`` can be used instead on machines with PCI.
1797DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
1798    "-usbdevice name add the host or guest USB device 'name'\n",
1799    QEMU_ARCH_ALL)
1801``-usbdevice devname``
1802    Add the USB device devname, and enable an on-board USB controller
1803    if possible and necessary (just like it can be done via
1804    ``-machine usb=on``). Note that this option is mainly intended for
1805    the user's convenience only. More fine-grained control can be
1806    achieved by selecting a USB host controller (if necessary) and the
1807    desired USB device via the ``-device`` option instead. For example,
1808    instead of using ``-usbdevice mouse`` it is possible to use
1809    ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse
1810    to a USB 3.0 controller instead (at least on machines that support
1811    PCI and do not have an USB controller enabled by default yet).
1812    For more details, see the chapter about
1813    :ref:`Connecting USB devices` in the System Emulation Users Guide.
1814    Possible devices for devname are:
1816    ``braille``
1817        Braille device. This will use BrlAPI to display the braille
1818        output on a real or fake device (i.e. it also creates a
1819        corresponding ``braille`` chardev automatically beside the
1820        ``usb-braille`` USB device).
1822    ``keyboard``
1823        Standard USB keyboard. Will override the PS/2 keyboard (if present).
1825    ``mouse``
1826        Virtual Mouse. This will override the PS/2 mouse emulation when
1827        activated.
1829    ``tablet``
1830        Pointer device that uses absolute coordinates (like a
1831        touchscreen). This means QEMU is able to report the mouse
1832        position without having to grab the mouse. Also overrides the
1833        PS/2 mouse emulation when activated.
1835    ``wacom-tablet``
1836        Wacom PenPartner USB tablet.
1843DEFHEADING(Display options:)
1845DEF("display", HAS_ARG, QEMU_OPTION_display,
1846#if defined(CONFIG_SPICE)
1847    "-display spice-app[,gl=on|off]\n"
1849#if defined(CONFIG_SDL)
1850    "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off][,gl=on|core|es|off]\n"
1851    "            [,grab-mod=<mod>][,show-cursor=on|off][,window-close=on|off]\n"
1853#if defined(CONFIG_GTK)
1854    "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
1855    "            [,show-cursor=on|off][,window-close=on|off]\n"
1857#if defined(CONFIG_VNC)
1858    "-display vnc=<display>[,<optargs>]\n"
1860#if defined(CONFIG_CURSES)
1861    "-display curses[,charset=<encoding>]\n"
1863#if defined(CONFIG_OPENGL)
1864    "-display egl-headless[,rendernode=<file>]\n"
1866    "-display none\n"
1867    "                select display backend type\n"
1868    "                The default display is equivalent to\n                "
1869#if defined(CONFIG_GTK)
1870            "\"-display gtk\"\n"
1871#elif defined(CONFIG_SDL)
1872            "\"-display sdl\"\n"
1873#elif defined(CONFIG_COCOA)
1874            "\"-display cocoa\"\n"
1875#elif defined(CONFIG_VNC)
1876            "\"-vnc localhost:0,to=99,id=default\"\n"
1878            "\"-display none\"\n"
1880    , QEMU_ARCH_ALL)
1882``-display type``
1883    Select type of display to use. This option is a replacement for the
1884    old style -sdl/-curses/... options. Use ``-display help`` to list
1885    the available display types. Valid values for type are
1887    ``spice-app[,gl=on|off]``
1888        Start QEMU as a Spice server and launch the default Spice client
1889        application. The Spice server will redirect the serial consoles
1890        and QEMU monitors. (Since 4.0)
1892    ``sdl``
1893        Display video output via SDL (usually in a separate graphics
1894        window; see the SDL documentation for other possibilities).
1895        Valid parameters are:
1897        ``grab-mod=<mods>`` : Used to select the modifier keys for toggling
1898        the mouse grabbing in conjunction with the "g" key. ``<mods>`` can be
1899        either ``lshift-lctrl-lalt`` or ``rctrl``.
1901        ``alt_grab=on|off`` : Use Control+Alt+Shift-g to toggle mouse grabbing.
1902        This parameter is deprecated - use ``grab-mod`` instead.
1904        ``ctrl_grab=on|off`` : Use Right-Control-g to toggle mouse grabbing.
1905        This parameter is deprecated - use ``grab-mod`` instead.
1907        ``gl=on|off|core|es`` : Use OpenGL for displaying
1909        ``show-cursor=on|off`` :  Force showing the mouse cursor
1911        ``window-close=on|off`` : Allow to quit qemu with window close button
1913    ``gtk``
1914        Display video output in a GTK window. This interface provides
1915        drop-down menus and other UI elements to configure and control
1916        the VM during runtime. Valid parameters are:
1918        ``full-screen=on|off`` : Start in fullscreen mode
1920        ``gl=on|off`` : Use OpenGL for displaying
1922        ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover
1924        ``show-cursor=on|off`` :  Force showing the mouse cursor
1926        ``window-close=on|off`` : Allow to quit qemu with window close button
1928    ``curses[,charset=<encoding>]``
1929        Display video output via curses. For graphics device models
1930        which support a text mode, QEMU can display this output using a
1931        curses/ncurses interface. Nothing is displayed when the graphics
1932        device is in graphical mode or if the graphics device does not
1933        support a text mode. Generally only the VGA device models
1934        support text mode. The font charset used by the guest can be
1935        specified with the ``charset`` option, for example
1936        ``charset=CP850`` for IBM CP850 encoding. The default is
1937        ``CP437``.
1939    ``egl-headless[,rendernode=<file>]``
1940        Offload all OpenGL operations to a local DRI device. For any
1941        graphical display, this display needs to be paired with either
1942        VNC or SPICE displays.
1944    ``vnc=<display>``
1945        Start a VNC server on display <display>
1947    ``none``
1948        Do not display video output. The guest will still see an
1949        emulated graphics card, but its output will not be displayed to
1950        the QEMU user. This option differs from the -nographic option in
1951        that it only affects what is done with video output; -nographic
1952        also changes the destination of the serial and parallel port
1953        data.
1956DEF("nographic", 0, QEMU_OPTION_nographic,
1957    "-nographic      disable graphical output and redirect serial I/Os to console\n",
1958    QEMU_ARCH_ALL)
1961    Normally, if QEMU is compiled with graphical window support, it
1962    displays output such as guest graphics, guest console, and the QEMU
1963    monitor in a window. With this option, you can totally disable
1964    graphical output so that QEMU is a simple command line application.
1965    The emulated serial port is redirected on the console and muxed with
1966    the monitor (unless redirected elsewhere explicitly). Therefore, you
1967    can still use QEMU to debug a Linux kernel with a serial console.
1968    Use C-a h for help on switching between the console and monitor.
1971DEF("curses", 0, QEMU_OPTION_curses,
1972    "-curses         shorthand for -display curses\n",
1973    QEMU_ARCH_ALL)
1976    Normally, if QEMU is compiled with graphical window support, it
1977    displays output such as guest graphics, guest console, and the QEMU
1978    monitor in a window. With this option, QEMU can display the VGA
1979    output when in text mode using a curses/ncurses interface. Nothing
1980    is displayed in graphical mode.
1983DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
1984    "-alt-grab       use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
1985    QEMU_ARCH_ALL)
1988    Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
1989    this also affects the special keys (for fullscreen, monitor-mode
1990    switching, etc). This option is deprecated - please use
1991    ``-display sdl,grab-mod=lshift-lctrl-lalt`` instead.
1994DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
1995    "-ctrl-grab      use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
1996    QEMU_ARCH_ALL)
1999    Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
2000    also affects the special keys (for fullscreen, monitor-mode
2001    switching, etc). This option is deprecated - please use
2002    ``-display sdl,grab-mod=rctrl`` instead.
2005DEF("no-quit", 0, QEMU_OPTION_no_quit,
2006    "-no-quit        disable SDL/GTK window close capability (deprecated)\n", QEMU_ARCH_ALL)
2009    Disable window close capability (SDL and GTK only). This option is
2010    deprecated, please use ``-display ...,window-close=off`` instead.
2013DEF("sdl", 0, QEMU_OPTION_sdl,
2014    "-sdl            shorthand for -display sdl\n", QEMU_ARCH_ALL)
2017    Enable SDL.
2020DEF("spice", HAS_ARG, QEMU_OPTION_spice,
2021    "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
2022    "       [,x509-key-file=<file>][,x509-key-password=<file>]\n"
2023    "       [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
2024    "       [,x509-dh-key-file=<file>][,addr=addr]\n"
2025    "       [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n"
2026    "       [,tls-ciphers=<list>]\n"
2027    "       [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
2028    "       [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
2029    "       [,sasl=on|off][,disable-ticketing=on|off]\n"
2030    "       [,password=<string>][,password-secret=<secret-id>]\n"
2031    "       [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
2032    "       [,jpeg-wan-compression=[auto|never|always]]\n"
2033    "       [,zlib-glz-wan-compression=[auto|never|always]]\n"
2034    "       [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n"
2035    "       [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n"
2036    "       [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
2037    "       [,gl=[on|off]][,rendernode=<file>]\n"
2038    "   enable spice\n"
2039    "   at least one of {port, tls-port} is mandatory\n",
2040    QEMU_ARCH_ALL)
2042``-spice option[,option[,...]]``
2043    Enable the spice remote desktop protocol. Valid options are
2045    ``port=<nr>``
2046        Set the TCP port spice is listening on for plaintext channels.
2048    ``addr=<addr>``
2049        Set the IP address spice is listening on. Default is any
2050        address.
2052    ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off``
2053        Force using the specified IP version.
2055    ``password=<string>``
2056        Set the password you need to authenticate.
2058        This option is deprecated and insecure because it leaves the
2059        password visible in the process listing. Use ``password-secret``
2060        instead.
2062    ``password-secret=<secret-id>``
2063        Set the ID of the ``secret`` object containing the password
2064        you need to authenticate.
2066    ``sasl=on|off``
2067        Require that the client use SASL to authenticate with the spice.
2068        The exact choice of authentication method used is controlled
2069        from the system / user's SASL configuration file for the 'qemu'
2070        service. This is typically found in /etc/sasl2/qemu.conf. If
2071        running QEMU as an unprivileged user, an environment variable
2072        SASL\_CONF\_PATH can be used to make it search alternate
2073        locations for the service config. While some SASL auth methods
2074        can also provide data encryption (eg GSSAPI), it is recommended
2075        that SASL always be combined with the 'tls' and 'x509' settings
2076        to enable use of SSL and server certificates. This ensures a
2077        data encryption preventing compromise of authentication
2078        credentials.
2080    ``disable-ticketing=on|off``
2081        Allow client connects without authentication.
2083    ``disable-copy-paste=on|off``
2084        Disable copy paste between the client and the guest.
2086    ``disable-agent-file-xfer=on|off``
2087        Disable spice-vdagent based file-xfer between the client and the
2088        guest.
2090    ``tls-port=<nr>``
2091        Set the TCP port spice is listening on for encrypted channels.
2093    ``x509-dir=<dir>``
2094        Set the x509 file directory. Expects same filenames as -vnc
2095        $display,x509=$dir
2097    ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>``
2098        The x509 file names can also be configured individually.
2100    ``tls-ciphers=<list>``
2101        Specify which ciphers to use.
2103    ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]``
2104        Force specific channel to be used with or without TLS
2105        encryption. The options can be specified multiple times to
2106        configure multiple channels. The special name "default" can be
2107        used to set the default mode. For channels which are not
2108        explicitly forced into one mode the spice client is allowed to
2109        pick tls/plaintext as he pleases.
2111    ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]``
2112        Configure image compression (lossless). Default is auto\_glz.
2114    ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]``
2115        Configure wan image compression (lossy for slow links). Default
2116        is auto.
2118    ``streaming-video=[off|all|filter]``
2119        Configure video stream detection. Default is off.
2121    ``agent-mouse=[on|off]``
2122        Enable/disable passing mouse events via vdagent. Default is on.
2124    ``playback-compression=[on|off]``
2125        Enable/disable audio stream compression (using celt 0.5.1).
2126        Default is on.
2128    ``seamless-migration=[on|off]``
2129        Enable/disable spice seamless migration. Default is off.
2131    ``gl=[on|off]``
2132        Enable/disable OpenGL context. Default is off.
2134    ``rendernode=<file>``
2135        DRM render node for OpenGL rendering. If not specified, it will
2136        pick the first available. (Since 2.9)
2139DEF("portrait", 0, QEMU_OPTION_portrait,
2140    "-portrait       rotate graphical output 90 deg left (only PXA LCD)\n",
2141    QEMU_ARCH_ALL)
2144    Rotate graphical output 90 deg left (only PXA LCD).
2147DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
2148    "-rotate <deg>   rotate graphical output some deg left (only PXA LCD)\n",
2149    QEMU_ARCH_ALL)
2151``-rotate deg``
2152    Rotate graphical output some deg left (only PXA LCD).
2155DEF("vga", HAS_ARG, QEMU_OPTION_vga,
2156    "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
2157    "                select video card type\n", QEMU_ARCH_ALL)
2159``-vga type``
2160    Select type of VGA card to emulate. Valid values for type are
2162    ``cirrus``
2163        Cirrus Logic GD5446 Video card. All Windows versions starting
2164        from Windows 95 should recognize and use this graphic card. For
2165        optimal performances, use 16 bit color depth in the guest and
2166        the host OS. (This card was the default before QEMU 2.2)
2168    ``std``
2169        Standard VGA card with Bochs VBE extensions. If your guest OS
2170        supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
2171        you want to use high resolution modes (>= 1280x1024x16) then you
2172        should use this option. (This card is the default since QEMU
2173        2.2)
2175    ``vmware``
2176        VMWare SVGA-II compatible adapter. Use it if you have
2177        sufficiently recent XFree86/XOrg server or Windows guest with a
2178        driver for this card.
2180    ``qxl``
2181        QXL paravirtual graphic card. It is VGA compatible (including
2182        VESA 2.0 VBE support). Works best with qxl guest drivers
2183        installed though. Recommended choice when using the spice
2184        protocol.
2186    ``tcx``
2187        (sun4m only) Sun TCX framebuffer. This is the default
2188        framebuffer for sun4m machines and offers both 8-bit and 24-bit
2189        colour depths at a fixed resolution of 1024x768.
2191    ``cg3``
2192        (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit
2193        framebuffer for sun4m machines available in both 1024x768
2194        (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people
2195        wishing to run older Solaris versions.
2197    ``virtio``
2198        Virtio VGA card.
2200    ``none``
2201        Disable VGA card.
2204DEF("full-screen", 0, QEMU_OPTION_full_screen,
2205    "-full-screen    start in full screen\n", QEMU_ARCH_ALL)
2208    Start in full screen.
2212    "-g WxH[xDEPTH]  Set the initial graphical resolution and depth\n",
2215``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]``
2216    Set the initial graphical resolution and depth (PPC, SPARC only).
2218    For PPC the default is 800x600x32.
2220    For SPARC with the TCX graphics device, the default is 1024x768x8
2221    with the option of 1024x768x24. For cgthree, the default is
2222    1024x768x8 with the option of 1152x900x8 for people who wish to use
2223    OBP.
2226DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
2227    "-vnc <display>  shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
2229``-vnc display[,option[,option[,...]]]``
2230    Normally, if QEMU is compiled with graphical window support, it
2231    displays output such as guest graphics, guest console, and the QEMU
2232    monitor in a window. With this option, you can have QEMU listen on
2233    VNC display display and redirect the VGA display over the VNC
2234    session. It is very useful to enable the usb tablet device when
2235    using this option (option ``-device usb-tablet``). When using the
2236    VNC display, you must use the ``-k`` parameter to set the keyboard
2237    layout if you are not using en-us. Valid syntax for the display is
2239    ``to=L``
2240        With this option, QEMU will try next available VNC displays,
2241        until the number L, if the origianlly defined "-vnc display" is
2242        not available, e.g. port 5900+display is already used by another
2243        application. By default, to=0.
2245    ``host:d``
2246        TCP connections will only be allowed from host on display d. By
2247        convention the TCP port is 5900+d. Optionally, host can be
2248        omitted in which case the server will accept connections from
2249        any host.
2251    ``unix:path``
2252        Connections will be allowed over UNIX domain sockets where path
2253        is the location of a unix socket to listen for connections on.
2255    ``none``
2256        VNC is initialized but not started. The monitor ``change``
2257        command can be used to later start the VNC server.
2259    Following the display value there may be one or more option flags
2260    separated by commas. Valid options are
2262    ``reverse=on|off``
2263        Connect to a listening VNC client via a "reverse" connection.
2264        The client is specified by the display. For reverse network
2265        connections (host:d,``reverse``), the d argument is a TCP port
2266        number, not a display number.
2268    ``websocket=on|off``
2269        Opens an additional TCP listening port dedicated to VNC
2270        Websocket connections. If a bare websocket option is given, the
2271        Websocket port is 5700+display. An alternative port can be
2272        specified with the syntax ``websocket``\ =port.
2274        If host is specified connections will only be allowed from this
2275        host. It is possible to control the websocket listen address
2276        independently, using the syntax ``websocket``\ =host:port.
2278        If no TLS credentials are provided, the websocket connection
2279        runs in unencrypted mode. If TLS credentials are provided, the
2280        websocket connection requires encrypted client connections.
2282    ``password=on|off``
2283        Require that password based authentication is used for client
2284        connections.
2286        The password must be set separately using the ``set_password``
2287        command in the :ref:`QEMU monitor`. The
2288        syntax to change your password is:
2289        ``set_password <protocol> <password>`` where <protocol> could be
2290        either "vnc" or "spice".
2292        If you would like to change <protocol> password expiration, you
2293        should use ``expire_password <protocol> <expiration-time>``
2294        where expiration time could be one of the following options:
2295        now, never, +seconds or UNIX time of expiration, e.g. +60 to
2296        make password expire in 60 seconds, or 1335196800 to make
2297        password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for
2298        this date and time).
2300        You can also use keywords "now" or "never" for the expiration
2301        time to allow <protocol> password to expire immediately or never
2302        expire.
2304    ``password-secret=<secret-id>``
2305        Require that password based authentication is used for client
2306        connections, using the password provided by the ``secret``
2307        object identified by ``secret-id``.
2309    ``tls-creds=ID``
2310        Provides the ID of a set of TLS credentials to use to secure the
2311        VNC server. They will apply to both the normal VNC server socket
2312        and the websocket socket (if enabled). Setting TLS credentials
2313        will cause the VNC server socket to enable the VeNCrypt auth
2314        mechanism. The credentials should have been previously created
2315        using the ``-object tls-creds`` argument.
2317    ``tls-authz=ID``
2318        Provides the ID of the QAuthZ authorization object against which
2319        the client's x509 distinguished name will validated. This object
2320        is only resolved at time of use, so can be deleted and recreated
2321        on the fly while the VNC server is active. If missing, it will
2322        default to denying access.
2324    ``sasl=on|off``
2325        Require that the client use SASL to authenticate with the VNC
2326        server. The exact choice of authentication method used is
2327        controlled from the system / user's SASL configuration file for
2328        the 'qemu' service. This is typically found in
2329        /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
2330        an environment variable SASL\_CONF\_PATH can be used to make it
2331        search alternate locations for the service config. While some
2332        SASL auth methods can also provide data encryption (eg GSSAPI),
2333        it is recommended that SASL always be combined with the 'tls'
2334        and 'x509' settings to enable use of SSL and server
2335        certificates. This ensures a data encryption preventing
2336        compromise of authentication credentials. See the
2337        :ref:`VNC security` section in the System Emulation Users Guide
2338        for details on using SASL authentication.
2340    ``sasl-authz=ID``
2341        Provides the ID of the QAuthZ authorization object against which
2342        the client's SASL username will validated. This object is only
2343        resolved at time of use, so can be deleted and recreated on the
2344        fly while the VNC server is active. If missing, it will default
2345        to denying access.
2347    ``acl=on|off``
2348        Legacy method for enabling authorization of clients against the
2349        x509 distinguished name and SASL username. It results in the
2350        creation of two ``authz-list`` objects with IDs of
2351        ``vnc.username`` and ``vnc.x509dname``. The rules for these
2352        objects must be configured with the HMP ACL commands.
2354        This option is deprecated and should no longer be used. The new
2355        ``sasl-authz`` and ``tls-authz`` options are a replacement.
2357    ``lossy=on|off``
2358        Enable lossy compression methods (gradient, JPEG, ...). If this
2359        option is set, VNC client may receive lossy framebuffer updates
2360        depending on its encoding settings. Enabling this option can
2361        save a lot of bandwidth at the expense of quality.
2363    ``non-adaptive=on|off``
2364        Disable adaptive encodings. Adaptive encodings are enabled by
2365        default. An adaptive encoding will try to detect frequently
2366        updated screen regions, and send updates in these regions using
2367        a lossy encoding (like JPEG). This can be really helpful to save
2368        bandwidth when playing videos. Disabling adaptive encodings
2369        restores the original static behavior of encodings like Tight.
2371    ``share=[allow-exclusive|force-shared|ignore]``
2372        Set display sharing policy. 'allow-exclusive' allows clients to
2373        ask for exclusive access. As suggested by the rfb spec this is
2374        implemented by dropping other connections. Connecting multiple
2375        clients in parallel requires all clients asking for a shared
2376        session (vncviewer: -shared switch). This is the default.
2377        'force-shared' disables exclusive client access. Useful for
2378        shared desktop sessions, where you don't want someone forgetting
2379        specify -shared disconnect everybody else. 'ignore' completely
2380        ignores the shared flag and allows everybody connect
2381        unconditionally. Doesn't conform to the rfb spec but is
2382        traditional QEMU behavior.
2384    ``key-delay-ms``
2385        Set keyboard delay, for key down and key up events, in
2386        milliseconds. Default is 10. Keyboards are low-bandwidth
2387        devices, so this slowdown can help the device and guest to keep
2388        up and not lose events in case events are arriving in bulk.
2389        Possible causes for the latter are flaky network connections, or
2390        scripts for automated testing.
2392    ``audiodev=audiodev``
2393        Use the specified audiodev when the VNC client requests audio
2394        transmission. When not using an -audiodev argument, this option
2395        must be omitted, otherwise is must be present and specify a
2396        valid audiodev.
2398    ``power-control=on|off``
2399        Permit the remote client to issue shutdown, reboot or reset power
2400        control requests.
2405ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2407DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2408    "-win2k-hack     use it when installing Windows 2000 to avoid a disk full bug\n",
2409    QEMU_ARCH_I386)
2412    Use it when installing Windows 2000 to avoid a disk full bug. After
2413    Windows 2000 is installed, you no longer need this option (this
2414    option slows down the IDE transfers).
2417DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2418    "-no-fd-bootchk  disable boot signature checking for floppy disks\n",
2419    QEMU_ARCH_I386)
2422    Disable boot signature checking for floppy disks in BIOS. May be
2423    needed to boot from old floppy disks.
2426DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
2427           "-no-acpi        disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2430    Disable ACPI (Advanced Configuration and Power Interface) support.
2431    Use it if your guest OS complains about ACPI problems (PC target
2432    machine only).
2435DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
2436    "-no-hpet        disable HPET\n", QEMU_ARCH_I386)
2439    Disable HPET support.
2442DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2443    "-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"
2444    "                ACPI table description\n", QEMU_ARCH_I386)
2446``-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]...]``
2447    Add ACPI table with specified header fields and context from
2448    specified files. For file=, take whole ACPI table from the specified
2449    files, including all ACPI headers (possible overridden by other
2450    options). For data=, only data portion of the table is used, all
2451    header information is specified in the command line. If a SLIC table
2452    is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
2453    fields will override the same in the RSDT and the FADT (a.k.a.
2454    FACP), in order to ensure the field matches required by the
2455    Microsoft SLIC spec and the ACPI spec.
2458DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2459    "-smbios file=binary\n"
2460    "                load SMBIOS entry from binary file\n"
2461    "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2462    "              [,uefi=on|off]\n"
2463    "                specify SMBIOS type 0 fields\n"
2464    "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2465    "              [,uuid=uuid][,sku=str][,family=str]\n"
2466    "                specify SMBIOS type 1 fields\n"
2467    "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2468    "              [,asset=str][,location=str]\n"
2469    "                specify SMBIOS type 2 fields\n"
2470    "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2471    "              [,sku=str]\n"
2472    "                specify SMBIOS type 3 fields\n"
2473    "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2474    "              [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
2475    "                specify SMBIOS type 4 fields\n"
2476    "-smbios type=11[,value=str][,path=filename]\n"
2477    "                specify SMBIOS type 11 fields\n"
2478    "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2479    "               [,asset=str][,part=str][,speed=%d]\n"
2480    "                specify SMBIOS type 17 fields\n"
2481    "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n"
2482    "                specify SMBIOS type 41 fields\n",
2485``-smbios file=binary``
2486    Load SMBIOS entry from binary file.
2488``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]``
2489    Specify SMBIOS type 0 fields
2491``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]``
2492    Specify SMBIOS type 1 fields
2494``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]``
2495    Specify SMBIOS type 2 fields
2497``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
2498    Specify SMBIOS type 3 fields
2500``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]``
2501    Specify SMBIOS type 4 fields
2503``-smbios type=11[,value=str][,path=filename]``
2504    Specify SMBIOS type 11 fields
2506    This argument can be repeated multiple times, and values are added in the order they are parsed.
2507    Applications intending to use OEM strings data are encouraged to use their application name as
2508    a prefix for the value string. This facilitates passing information for multiple applications
2509    concurrently.
2511    The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax
2512    loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes.
2514    Both the ``value`` and ``path`` options can be repeated multiple times and will be added to
2515    the SMBIOS table in the order in which they appear.
2517    Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535
2518    bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the
2519    guest. Instead it should be used as a indicator to inform the guest where to locate the real
2520    data set, for example, by specifying the serial ID of a block device.
2522    An example passing three strings is
2524    .. parsed-literal::
2526        -smbios type=11,value=cloud-init:ds=nocloud-net;s=,\\
2527                        value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\
2528                        path=/some/file/with/oemstringsdata.txt
2530    In the guest OS this is visible with the ``dmidecode`` command
2532     .. parsed-literal::
2534         $ dmidecode -t 11
2535         Handle 0x0E00, DMI type 11, 5 bytes
2536         OEM Strings
2537              String 1: cloud-init:ds=nocloud-net;s=
2538              String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os
2539              String 3: myapp:some extra data
2542``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]``
2543    Specify SMBIOS type 17 fields
2545``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]``
2546    Specify SMBIOS type 41 fields
2548    This argument can be repeated multiple times.  Its main use is to allow network interfaces be created
2549    as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface
2550    position on the PCI bus.
2552    Here is an example of use:
2554    .. parsed-literal::
2556        -netdev user,id=internet \\
2557        -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\
2558        -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev
2560    In the guest OS, the device should then appear as ``eno1``:
2562    ..parsed-literal::
2564         $ ip -brief l
2565         lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
2566         eno1             UP             50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP>
2568    Currently, the PCI device has to be attached to the root bus.
2574DEFHEADING(Network options:)
2576DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2577#ifdef CONFIG_SLIRP
2578    "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n"
2579    "         [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2580    "         [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2581    "         [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2582    "         [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2583#ifndef _WIN32
2584                                             "[,smb=dir[,smbserver=addr]]\n"
2586    "                configure a user mode network backend with ID 'str',\n"
2587    "                its DHCP server and optional services\n"
2589#ifdef _WIN32
2590    "-netdev tap,id=str,ifname=name\n"
2591    "                configure a host TAP network backend with ID 'str'\n"
2593    "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2594    "         [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2595    "         [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2596    "         [,poll-us=n]\n"
2597    "                configure a host TAP network backend with ID 'str'\n"
2598    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2599    "                use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2600    "                to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2601    "                to deconfigure it\n"
2602    "                use '[down]script=no' to disable script execution\n"
2603    "                use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2604    "                configure it\n"
2605    "                use 'fd=h' to connect to an already opened TAP interface\n"
2606    "                use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2607    "                use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2608    "                default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2609    "                use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2610    "                use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2611    "                use vhost=on to enable experimental in kernel accelerator\n"
2612    "                    (only has effect for virtio guests which use MSIX)\n"
2613    "                use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2614    "                use 'vhostfd=h' to connect to an already opened vhost net device\n"
2615    "                use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2616    "                use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2617    "                use 'poll-us=n' to specify the maximum number of microseconds that could be\n"
2618    "                spent on busy polling for vhost net\n"
2619    "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2620    "                configure a host TAP network backend with ID 'str' that is\n"
2621    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2622    "                using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2624#ifdef __linux__
2625    "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2626    "         [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n"
2627    "         [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n"
2628    "         [,rxcookie=rxcookie][,offset=offset]\n"
2629    "                configure a network backend with ID 'str' connected to\n"
2630    "                an Ethernet over L2TPv3 pseudowire.\n"
2631    "                Linux kernel 3.3+ as well as most routers can talk\n"
2632    "                L2TPv3. This transport allows connecting a VM to a VM,\n"
2633    "                VM to a router and even VM to Host. It is a nearly-universal\n"
2634    "                standard (RFC3931). Note - this implementation uses static\n"
2635    "                pre-configured tunnels (same as the Linux kernel).\n"
2636    "                use 'src=' to specify source address\n"
2637    "                use 'dst=' to specify destination address\n"
2638    "                use 'udp=on' to specify udp encapsulation\n"
2639    "                use 'srcport=' to specify source udp port\n"
2640    "                use 'dstport=' to specify destination udp port\n"
2641    "                use 'ipv6=on' to force v6\n"
2642    "                L2TPv3 uses cookies to prevent misconfiguration as\n"
2643    "                well as a weak security measure\n"
2644    "                use 'rxcookie=0x012345678' to specify a rxcookie\n"
2645    "                use 'txcookie=0x012345678' to specify a txcookie\n"
2646    "                use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2647    "                use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2648    "                use 'pincounter=on' to work around broken counter handling in peer\n"
2649    "                use 'offset=X' to add an extra offset between header and data\n"
2651    "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2652    "                configure a network backend to connect to another network\n"
2653    "                using a socket connection\n"
2654    "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2655    "                configure a network backend to connect to a multicast maddr and port\n"
2656    "                use 'localaddr=addr' to specify the host address to send packets from\n"
2657    "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2658    "                configure a network backend to connect to another network\n"
2659    "                using an UDP tunnel\n"
2660#ifdef CONFIG_VDE
2661    "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2662    "                configure a network backend to connect to port 'n' of a vde switch\n"
2663    "                running on host and listening for incoming connections on 'socketpath'.\n"
2664    "                Use group 'groupname' and mode 'octalmode' to change default\n"
2665    "                ownership and permissions for communication port.\n"
2667#ifdef CONFIG_NETMAP
2668    "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2669    "                attach to the existing netmap-enabled network interface 'name', or to a\n"
2670    "                VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2671    "                netmap device, defaults to '/dev/netmap')\n"
2673#ifdef CONFIG_POSIX
2674    "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2675    "                configure a vhost-user network, backed by a chardev 'dev'\n"
2677#ifdef __linux__
2678    "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n"
2679    "                configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n"
2681    "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2682    "                configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2683DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2684    "-nic [tap|bridge|"
2685#ifdef CONFIG_SLIRP
2686    "user|"
2688#ifdef __linux__
2689    "l2tpv3|"
2691#ifdef CONFIG_VDE
2692    "vde|"
2694#ifdef CONFIG_NETMAP
2695    "netmap|"
2697#ifdef CONFIG_POSIX
2698    "vhost-user|"
2700    "socket][,option][,...][mac=macaddr]\n"
2701    "                initialize an on-board / default host NIC (using MAC address\n"
2702    "                macaddr) and connect it to the given host network backend\n"
2703    "-nic none       use it alone to have zero network devices (the default is to\n"
2704    "                provided a 'user' network connection)\n",
2705    QEMU_ARCH_ALL)
2706DEF("net", HAS_ARG, QEMU_OPTION_net,
2707    "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2708    "                configure or create an on-board (or machine default) NIC and\n"
2709    "                connect it to hub 0 (please use -nic unless you need a hub)\n"
2710    "-net ["
2711#ifdef CONFIG_SLIRP
2712    "user|"
2714    "tap|"
2715    "bridge|"
2716#ifdef CONFIG_VDE
2717    "vde|"
2719#ifdef CONFIG_NETMAP
2720    "netmap|"
2722    "socket][,option][,option][,...]\n"
2723    "                old way to initialize a host network interface\n"
2724    "                (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
2726``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]``
2727    This option is a shortcut for configuring both the on-board
2728    (default) guest NIC hardware and the host network backend in one go.
2729    The host backend options are the same as with the corresponding
2730    ``-netdev`` options below. The guest NIC model can be set with
2731    ``model=modelname``. Use ``model=help`` to list the available device
2732    types. The hardware MAC address can be set with ``mac=macaddr``.
2734    The following two example do exactly the same, to show how ``-nic``
2735    can be used to shorten the command line length:
2737    .. parsed-literal::
2739        |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
2740        |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
2742``-nic none``
2743    Indicate that no network devices should be configured. It is used to
2744    override the default configuration (default NIC with "user" host
2745    network backend) which is activated if no other networking options
2746    are provided.
2748``-netdev user,id=id[,option][,option][,...]``
2749    Configure user mode host network backend which requires no
2750    administrator privilege to run. Valid options are:
2752    ``id=id``
2753        Assign symbolic name for use in monitor commands.
2755    ``ipv4=on|off and ipv6=on|off``
2756        Specify that either IPv4 or IPv6 must be enabled. If neither is
2757        specified both protocols are enabled.
2759    ``net=addr[/mask]``
2760        Set IP network address the guest will see. Optionally specify
2761        the netmask, either in the form a.b.c.d or as number of valid
2762        top-most bits. Default is
2764    ``host=addr``
2765        Specify the guest-visible address of the host. Default is the
2766        2nd IP in the guest network, i.e. x.x.x.2.
2768    ``ipv6-net=addr[/int]``
2769        Set IPv6 network address the guest will see (default is
2770        fec0::/64). The network prefix is given in the usual hexadecimal
2771        IPv6 address notation. The prefix size is optional, and is given
2772        as the number of valid top-most bits (default is 64).
2774    ``ipv6-host=addr``
2775        Specify the guest-visible IPv6 address of the host. Default is
2776        the 2nd IPv6 in the guest network, i.e. xxxx::2.
2778    ``restrict=on|off``
2779        If this option is enabled, the guest will be isolated, i.e. it
2780        will not be able to contact the host and no guest IP packets
2781        will be routed over the host to the outside. This option does
2782        not affect any explicitly set forwarding rules.
2784    ``hostname=name``
2785        Specifies the client hostname reported by the built-in DHCP
2786        server.
2788    ``dhcpstart=addr``
2789        Specify the first of the 16 IPs the built-in DHCP server can
2790        assign. Default is the 15th to 31st IP in the guest network,
2791        i.e. x.x.x.15 to x.x.x.31.
2793    ``dns=addr``
2794        Specify the guest-visible address of the virtual nameserver. The
2795        address must be different from the host address. Default is the
2796        3rd IP in the guest network, i.e. x.x.x.3.
2798    ``ipv6-dns=addr``
2799        Specify the guest-visible address of the IPv6 virtual
2800        nameserver. The address must be different from the host address.
2801        Default is the 3rd IP in the guest network, i.e. xxxx::3.
2803    ``dnssearch=domain``
2804        Provides an entry for the domain-search list sent by the
2805        built-in DHCP server. More than one domain suffix can be
2806        transmitted by specifying this option multiple times. If
2807        supported, this will cause the guest to automatically try to
2808        append the given domain suffix(es) in case a domain name can not
2809        be resolved.
2811        Example:
2813        .. parsed-literal::
2815            |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
2817    ``domainname=domain``
2818        Specifies the client domain name reported by the built-in DHCP
2819        server.
2821    ``tftp=dir``
2822        When using the user mode network stack, activate a built-in TFTP
2823        server. The files in dir will be exposed as the root of a TFTP
2824        server. The TFTP client on the guest must be configured in
2825        binary mode (use the command ``bin`` of the Unix TFTP client).
2827    ``tftp-server-name=name``
2828        In BOOTP reply, broadcast name as the "TFTP server name"
2829        (RFC2132 option 66). This can be used to advise the guest to
2830        load boot files or configurations from a different server than
2831        the host address.
2833    ``bootfile=file``
2834        When using the user mode network stack, broadcast file as the
2835        BOOTP filename. In conjunction with ``tftp``, this can be used
2836        to network boot a guest from a local directory.
2838        Example (using pxelinux):
2840        .. parsed-literal::
2842            |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\
2843                -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
2845    ``smb=dir[,smbserver=addr]``
2846        When using the user mode network stack, activate a built-in SMB
2847        server so that Windows OSes can access to the host files in
2848        ``dir`` transparently. The IP address of the SMB server can be
2849        set to addr. By default the 4th IP in the guest network is used,
2850        i.e. x.x.x.4.
2852        In the guest Windows OS, the line:
2854        ::
2856   smbserver
2858        must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows
2859        9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows
2860        NT/2000).
2862        Then ``dir`` can be accessed in ``\\smbserver\qemu``.
2864        Note that a SAMBA server must be installed on the host OS.
2866    ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
2867        Redirect incoming TCP or UDP connections to the host port
2868        hostport to the guest IP address guestaddr on guest port
2869        guestport. If guestaddr is not specified, its value is x.x.x.15
2870        (default first address given by the built-in DHCP server). By
2871        specifying hostaddr, the rule can be bound to a specific host
2872        interface. If no connection type is set, TCP is used. This
2873        option can be given multiple times.
2875        For example, to redirect host X11 connection from screen 1 to
2876        guest screen 0, use the following:
2878        .. parsed-literal::
2880            # on the host
2881            |qemu_system| -nic user,hostfwd=tcp:
2882            # this host xterm should open in the guest X11 server
2883            xterm -display :1
2885        To redirect telnet connections from host port 5555 to telnet
2886        port on the guest, use the following:
2888        .. parsed-literal::
2890            # on the host
2891            |qemu_system| -nic user,hostfwd=tcp::5555-:23
2892            telnet localhost 5555
2894        Then when you use on the host ``telnet localhost 5555``, you
2895        connect to the guest telnet server.
2897    ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command``
2898        Forward guest TCP connections to the IP address server on port
2899        port to the character device dev or to a program executed by
2900        cmd:command which gets spawned for each connection. This option
2901        can be given multiple times.
2903        You can either use a chardev directly and have that one used
2904        throughout QEMU's lifetime, like in the following example:
2906        .. parsed-literal::
2908            # open on bootup, connect to it whenever
2909            # the guest accesses it
2910            |qemu_system| -nic user,guestfwd=tcp:
2912        Or you can execute a command on every TCP connection established
2913        by the guest, so that QEMU behaves similar to an inetd process
2914        for that virtual server:
2916        .. parsed-literal::
2918            # call "netcat 4321" on every TCP connection to
2919            # and connect the TCP stream to its stdin/stdout
2920            |qemu_system| -nic  'user,id=n1,guestfwd=tcp: 4321'
2922``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
2923    Configure a host TAP network backend with ID id.
2925    Use the network script file to configure it and the network script
2926    dfile to deconfigure it. If name is not provided, the OS
2927    automatically provides one. The default network configure script is
2928    ``/etc/qemu-ifup`` and the default network deconfigure script is
2929    ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
2930    disable script execution.
2932    If running QEMU as an unprivileged user, use the network helper
2933    to configure the TAP interface and attach it to the bridge.
2934    The default network helper executable is
2935    ``/path/to/qemu-bridge-helper`` and the default bridge device is
2936    ``br0``.
2938    ``fd``\ =h can be used to specify the handle of an already opened
2939    host TAP interface.
2941    Examples:
2943    .. parsed-literal::
2945        #launch a QEMU instance with the default network script
2946        |qemu_system| linux.img -nic tap
2948    .. parsed-literal::
2950        #launch a QEMU instance with two NICs, each one connected
2951        #to a TAP device
2952        |qemu_system| linux.img \\
2953                -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\
2954                -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
2956    .. parsed-literal::
2958        #launch a QEMU instance with the default network helper to
2959        #connect a TAP device to bridge br0
2960        |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
2961                -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
2963``-netdev bridge,id=id[,br=bridge][,helper=helper]``
2964    Connect a host TAP network interface to a host bridge device.
2966    Use the network helper helper to configure the TAP interface and
2967    attach it to the bridge. The default network helper executable is
2968    ``/path/to/qemu-bridge-helper`` and the default bridge device is
2969    ``br0``.
2971    Examples:
2973    .. parsed-literal::
2975        #launch a QEMU instance with the default network helper to
2976        #connect a TAP device to bridge br0
2977        |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
2979    .. parsed-literal::
2981        #launch a QEMU instance with the default network helper to
2982        #connect a TAP device to bridge qemubr0
2983        |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
2985``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
2986    This host network backend can be used to connect the guest's network
2987    to another QEMU virtual machine using a TCP socket connection. If
2988    ``listen`` is specified, QEMU waits for incoming connections on port
2989    (host is optional). ``connect`` is used to connect to another QEMU
2990    instance using the ``listen`` option. ``fd``\ =h specifies an
2991    already opened TCP socket.
2993    Example:
2995    .. parsed-literal::
2997        # launch a first QEMU instance
2998        |qemu_system| linux.img \\
2999                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3000                         -netdev socket,id=n1,listen=:1234
3001        # connect the network of this instance to the network of the first instance
3002        |qemu_system| linux.img \\
3003                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
3004                         -netdev socket,id=n2,connect=
3006``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]``
3007    Configure a socket host network backend to share the guest's network
3008    traffic with another QEMU virtual machines using a UDP multicast
3009    socket, effectively making a bus for every QEMU with same multicast
3010    address maddr and port. NOTES:
3012    1. Several QEMU can be running on different hosts and share same bus
3013       (assuming correct multicast setup for these hosts).
3015    2. mcast support is compatible with User Mode Linux (argument
3016       ``ethN=mcast``), see http://user-mode-linux.sf.net.
3018    3. Use ``fd=h`` to specify an already opened UDP multicast socket.
3020    Example:
3022    .. parsed-literal::
3024        # launch one QEMU instance
3025        |qemu_system| linux.img \\
3026                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3027                         -netdev socket,id=n1,mcast=
3028        # launch another QEMU instance on same "bus"
3029        |qemu_system| linux.img \\
3030                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
3031                         -netdev socket,id=n2,mcast=
3032        # launch yet another QEMU instance on same "bus"
3033        |qemu_system| linux.img \\
3034                         -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\
3035                         -netdev socket,id=n3,mcast=
3037    Example (User Mode Linux compat.):
3039    .. parsed-literal::
3041        # launch QEMU instance (note mcast address selected is UML's default)
3042        |qemu_system| linux.img \\
3043                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3044                         -netdev socket,id=n1,mcast=
3045        # launch UML
3046        /path/to/linux ubd0=/path/to/root_fs eth0=mcast
3048    Example (send packets from host's
3050    .. parsed-literal::
3052        |qemu_system| linux.img \\
3053                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3054                         -netdev socket,id=n1,mcast=,localaddr=
3056``-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]``
3057    Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
3058    is a popular protocol to transport Ethernet (and other Layer 2) data
3059    frames between two systems. It is present in routers, firewalls and
3060    the Linux kernel (from version 3.3 onwards).
3062    This transport allows a VM to communicate to another VM, router or
3063    firewall directly.
3065    ``src=srcaddr``
3066        source address (mandatory)
3068    ``dst=dstaddr``
3069        destination address (mandatory)
3071    ``udp``
3072        select udp encapsulation (default is ip).
3074    ``srcport=srcport``
3075        source udp port.
3077    ``dstport=dstport``
3078        destination udp port.
3080    ``ipv6``
3081        force v6, otherwise defaults to v4.
3083    ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
3084        Cookies are a weak form of security in the l2tpv3 specification.
3085        Their function is mostly to prevent misconfiguration. By default
3086        they are 32 bit.
3088    ``cookie64``
3089        Set cookie size to 64 bit instead of the default 32
3091    ``counter=off``
3092        Force a 'cut-down' L2TPv3 with no counter as in
3093        draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
3095    ``pincounter=on``
3096        Work around broken counter handling in peer. This may also help
3097        on networks which have packet reorder.
3099    ``offset=offset``
3100        Add an extra offset between header and data
3102    For example, to attach a VM running on host via L2TPv3 to
3103    the bridge br-lan on the remote Linux host
3105    .. parsed-literal::
3107        # Setup tunnel on linux host using raw ip as encapsulation
3108        # on
3109        ip l2tp add tunnel remote local tunnel_id 1 peer_tunnel_id 1 \\
3110            encap udp udp_sport 16384 udp_dport 16384
3111        ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\
3112            0xFFFFFFFF peer_session_id 0xFFFFFFFF
3113        ifconfig vmtunnel0 mtu 1500
3114        ifconfig vmtunnel0 up
3115        brctl addif br-lan vmtunnel0
3118        # on
3119        # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
3121        |qemu_system| linux.img -device e1000,netdev=n1 \\
3122            -netdev l2tpv3,id=n1,src=,dst=,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
3124``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
3125    Configure VDE backend to connect to PORT n of a vde switch running
3126    on host and listening for incoming connections on socketpath. Use
3127    GROUP groupname and MODE octalmode to change default ownership and
3128    permissions for communication port. This option is only available if
3129    QEMU has been compiled with vde support enabled.
3131    Example:
3133    .. parsed-literal::
3135        # launch vde switch
3136        vde_switch -F -sock /tmp/myswitch
3137        # launch QEMU instance
3138        |qemu_system| linux.img -nic vde,sock=/tmp/myswitch
3140``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
3141    Establish a vhost-user netdev, backed by a chardev id. The chardev
3142    should be a unix domain socket backed one. The vhost-user uses a
3143    specifically defined protocol to pass vhost ioctl replacement
3144    messages to an application on the other end of the socket. On
3145    non-MSIX guests, the feature can be forced with vhostforce. Use
3146    'queues=n' to specify the number of queues to be created for
3147    multiqueue vhost-user.
3149    Example:
3151    ::
3153        qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
3154             -numa node,memdev=mem \
3155             -chardev socket,id=chr0,path=/path/to/socket \
3156             -netdev type=vhost-user,id=net0,chardev=chr0 \
3157             -device virtio-net-pci,netdev=net0
3159``-netdev vhost-vdpa,vhostdev=/path/to/dev``
3160    Establish a vhost-vdpa netdev.
3162    vDPA device is a device that uses a datapath which complies with
3163    the virtio specifications with a vendor specific control path.
3164    vDPA devices can be both physically located on the hardware or
3165    emulated by software.
3167``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
3168    Create a hub port on the emulated hub with ID hubid.
3170    The hubport netdev lets you connect a NIC to a QEMU emulated hub
3171    instead of a single netdev. Alternatively, you can also connect the
3172    hubport to another netdev with ID nd by using the ``netdev=nd``
3173    option.
3175``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
3176    Legacy option to configure or create an on-board (or machine
3177    default) Network Interface Card(NIC) and connect it either to the
3178    emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
3179    If model is omitted, then the default NIC model associated with the
3180    machine type is used. Note that the default NIC model may change in
3181    future QEMU releases, so it is highly recommended to always specify
3182    a model. Optionally, the MAC address can be changed to mac, the
3183    device address set to addr (PCI cards only), and a name can be
3184    assigned for use in monitor commands. Optionally, for PCI cards, you
3185    can specify the number v of MSI-X vectors that the card should have;
3186    this option currently only affects virtio cards; set v = 0 to
3187    disable MSI-X. If no ``-net`` option is specified, a single NIC is
3188    created. QEMU can emulate several different models of network card.
3189    Use ``-net nic,model=help`` for a list of available devices for your
3190    target.
3192``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
3193    Configure a host network backend (with the options corresponding to
3194    the same ``-netdev`` option) and connect it to the emulated hub 0
3195    (the default hub). Use name to specify the name of the hub port.
3200DEFHEADING(Character device options:)
3202DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
3203    "-chardev help\n"
3204    "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3205    "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n"
3206    "         [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n"
3207    "         [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
3208    "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n"
3209    "         [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n"
3210    "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
3211    "         [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n"
3212    "         [,logfile=PATH][,logappend=on|off]\n"
3213    "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3214    "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
3215    "         [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3216    "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
3217    "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3218    "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3219#ifdef _WIN32
3220    "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3221    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3223    "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3224    "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
3226#ifdef CONFIG_BRLAPI
3227    "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3229#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
3230        || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
3231    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3232    "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3234#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
3235    "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3236    "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3238#if defined(CONFIG_SPICE)
3239    "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3240    "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3242    , QEMU_ARCH_ALL
3246The general form of a character device option is:
3248``-chardev backend,id=id[,mux=on|off][,options]``
3249    Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
3250    ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
3251    ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``,
3252    ``spicevmc``, ``spiceport``. The specific backend will determine the
3253    applicable options.
3255    Use ``-chardev help`` to print all available chardev backend types.
3257    All devices must have an id, which can be any string up to 127
3258    characters long. It is used to uniquely identify this device in
3259    other command line directives.
3261    A character device may be used in multiplexing mode by multiple
3262    front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
3263    a "1:N" device, and here the "1" end is your specified chardev
3264    backend, and the "N" end is the various parts of QEMU that can talk
3265    to a chardev. If you create a chardev with ``id=myid`` and
3266    ``mux=on``, QEMU will create a multiplexer with your specified ID,
3267    and you can then configure multiple front ends to use that chardev
3268    ID for their input/output. Up to four different front ends can be
3269    connected to a single multiplexed chardev. (Without multiplexing
3270    enabled, a chardev can only be used by a single front end.) For
3271    instance you could use this to allow a single stdio chardev to be
3272    used by two serial ports and the QEMU monitor:
3274    ::
3276        -chardev stdio,mux=on,id=char0 \
3277        -mon chardev=char0,mode=readline \
3278        -serial chardev:char0 \
3279        -serial chardev:char0
3281    You can have more than one multiplexer in a system configuration;
3282    for instance you could have a TCP port multiplexed between UART 0
3283    and UART 1, and stdio multiplexed between the QEMU monitor and a
3284    parallel port:
3286    ::
3288        -chardev stdio,mux=on,id=char0 \
3289        -mon chardev=char0,mode=readline \
3290        -parallel chardev:char0 \
3291        -chardev tcp,...,mux=on,id=char1 \
3292        -serial chardev:char1 \
3293        -serial chardev:char1
3295    When you're using a multiplexed character device, some escape
3296    sequences are interpreted in the input. See the chapter about
3297    :ref:`keys in the character backend multiplexer` in the
3298    System Emulation Users Guide for more details.
3300    Note that some other command line options may implicitly create
3301    multiplexed character backends; for instance ``-serial mon:stdio``
3302    creates a multiplexed stdio backend connected to the serial port and
3303    the QEMU monitor, and ``-nographic`` also multiplexes the console
3304    and the monitor to stdio.
3306    There is currently no support for multiplexing in the other
3307    direction (where a single QEMU front end takes input and output from
3308    multiple chardevs).
3310    Every backend supports the ``logfile`` option, which supplies the
3311    path to a file to record all data transmitted via the backend. The
3312    ``logappend`` option controls whether the log file will be truncated
3313    or appended to when opened.
3315The available backends are:
3317``-chardev null,id=id``
3318    A void device. This device will not emit any data, and will drop any
3319    data it receives. The null backend does not take any options.
3321``-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]``
3322    Create a two-way stream socket, which can be either a TCP or a unix
3323    socket. A unix socket will be created if ``path`` is specified.
3324    Behaviour is undefined if TCP options are specified for a unix
3325    socket.
3327    ``server=on|off`` specifies that the socket shall be a listening socket.
3329    ``wait=on|off`` specifies that QEMU should not block waiting for a client
3330    to connect to a listening socket.
3332    ``telnet=on|off`` specifies that traffic on the socket should interpret
3333    telnet escape sequences.
3335    ``websocket=on|off`` specifies that the socket uses WebSocket protocol for
3336    communication.
3338    ``reconnect`` sets the timeout for reconnecting on non-server
3339    sockets when the remote end goes away. qemu will delay this many
3340    seconds and then attempt to reconnect. Zero disables reconnecting,
3341    and is the default.
3343    ``tls-creds`` requests enablement of the TLS protocol for
3344    encryption, and specifies the id of the TLS credentials to use for
3345    the handshake. The credentials must be previously created with the
3346    ``-object tls-creds`` argument.
3348    ``tls-auth`` provides the ID of the QAuthZ authorization object
3349    against which the client's x509 distinguished name will be
3350    validated. This object is only resolved at time of use, so can be
3351    deleted and recreated on the fly while the chardev server is active.
3352    If missing, it will default to denying access.
3354    TCP and unix socket options are given below:
3356    ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]``
3357        ``host`` for a listening socket specifies the local address to
3358        be bound. For a connecting socket species the remote host to
3359        connect to. ``host`` is optional for listening sockets. If not
3360        specified it defaults to ````.
3362        ``port`` for a listening socket specifies the local port to be
3363        bound. For a connecting socket specifies the port on the remote
3364        host to connect to. ``port`` can be given as either a port
3365        number or a service name. ``port`` is required.
3367        ``to`` is only relevant to listening sockets. If it is
3368        specified, and ``port`` cannot be bound, QEMU will attempt to
3369        bind to subsequent ports up to and including ``to`` until it
3370        succeeds. ``to`` must be specified as a port number.
3372        ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4
3373        or IPv6 must be used. If neither is specified the socket may
3374        use either protocol.
3376        ``nodelay=on|off`` disables the Nagle algorithm.
3378    ``unix options: path=path[,abstract=on|off][,tight=on|off]``
3379        ``path`` specifies the local path of the unix socket. ``path``
3380        is required.
3381        ``abstract=on|off`` specifies the use of the abstract socket namespace,
3382        rather than the filesystem.  Optional, defaults to false.
3383        ``tight=on|off`` sets the socket length of abstract sockets to their minimum,
3384        rather than the full sun_path length.  Optional, defaults to true.
3386``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]``
3387    Sends all traffic from the guest to a remote host over UDP.
3389    ``host`` specifies the remote host to connect to. If not specified
3390    it defaults to ``localhost``.
3392    ``port`` specifies the port on the remote host to connect to.
3393    ``port`` is required.
3395    ``localaddr`` specifies the local address to bind to. If not
3396    specified it defaults to ````.
3398    ``localport`` specifies the local port to bind to. If not specified
3399    any available local port will be used.
3401    ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used.
3402    If neither is specified the device may use either protocol.
3404``-chardev msmouse,id=id``
3405    Forward QEMU's emulated msmouse events to the guest. ``msmouse``
3406    does not take any options.
3408``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
3409    Connect to a QEMU text console. ``vc`` may optionally be given a
3410    specific size.
3412    ``width`` and ``height`` specify the width and height respectively
3413    of the console, in pixels.
3415    ``cols`` and ``rows`` specify that the console be sized to fit a
3416    text console with the given dimensions.
3418``-chardev ringbuf,id=id[,size=size]``
3419    Create a ring buffer with fixed size ``size``. size must be a power
3420    of two and defaults to ``64K``.
3422``-chardev file,id=id,path=path``
3423    Log all traffic received from the guest to a file.
3425    ``path`` specifies the path of the file to be opened. This file will
3426    be created if it does not already exist, and overwritten if it does.
3427    ``path`` is required.
3429``-chardev pipe,id=id,path=path``
3430    Create a two-way connection to the guest. The behaviour differs
3431    slightly between Windows hosts and other hosts:
3433    On Windows, a single duplex pipe will be created at
3434    ``\\.pipe\path``.
3436    On other hosts, 2 pipes will be created called ``path.in`` and
3437    ``path.out``. Data written to ``path.in`` will be received by the
3438    guest. Data written by the guest can be read from ``path.out``. QEMU
3439    will not create these fifos, and requires them to be present.
3441    ``path`` forms part of the pipe path as described above. ``path`` is
3442    required.
3444``-chardev console,id=id``
3445    Send traffic from the guest to QEMU's standard output. ``console``
3446    does not take any options.
3448    ``console`` is only available on Windows hosts.
3450``-chardev serial,id=id,path=path``
3451    Send traffic from the guest to a serial device on the host.
3453    On Unix hosts serial will actually accept any tty device, not only
3454    serial lines.
3456    ``path`` specifies the name of the serial device to open.
3458``-chardev pty,id=id``
3459    Create a new pseudo-terminal on the host and connect to it. ``pty``
3460    does not take any options.
3462    ``pty`` is not available on Windows hosts.
3464``-chardev stdio,id=id[,signal=on|off]``
3465    Connect to standard input and standard output of the QEMU process.
3467    ``signal`` controls if signals are enabled on the terminal, that
3468    includes exiting QEMU with the key sequence Control-c. This option
3469    is enabled by default, use ``signal=off`` to disable it.
3471``-chardev braille,id=id``
3472    Connect to a local BrlAPI server. ``braille`` does not take any
3473    options.
3475``-chardev tty,id=id,path=path``
3476    ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD
3477    and DragonFlyBSD hosts. It is an alias for ``serial``.
3479    ``path`` specifies the path to the tty. ``path`` is required.
3481``-chardev parallel,id=id,path=path``
3482  \
3483``-chardev parport,id=id,path=path``
3484    ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
3485    hosts.
3487    Connect to a local parallel port.
3489    ``path`` specifies the path to the parallel port device. ``path`` is
3490    required.
3492``-chardev spicevmc,id=id,debug=debug,name=name``
3493    ``spicevmc`` is only available when spice support is built in.
3495    ``debug`` debug level for spicevmc
3497    ``name`` name of spice channel to connect to
3499    Connect to a spice virtual machine channel, such as vdiport.
3501``-chardev spiceport,id=id,debug=debug,name=name``
3502    ``spiceport`` is only available when spice support is built in.
3504    ``debug`` debug level for spicevmc
3506    ``name`` name of spice port to connect to
3508    Connect to a spice port, allowing a Spice client to handle the
3509    traffic identified by a name (preferably a fqdn).
3514#ifdef CONFIG_TPM
3515DEFHEADING(TPM device options:)
3517DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3518    "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3519    "                use path to provide path to a character device; default is /dev/tpm0\n"
3520    "                use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
3521    "                not provided it will be searched for in /sys/class/misc/tpm?/device\n"
3522    "-tpmdev emulator,id=id,chardev=dev\n"
3523    "                configure the TPM device using chardev backend\n",
3524    QEMU_ARCH_ALL)
3526The general form of a TPM device option is:
3528``-tpmdev backend,id=id[,options]``
3529    The specific backend type will determine the applicable options. The
3530    ``-tpmdev`` option creates the TPM backend and requires a
3531    ``-device`` option that specifies the TPM frontend interface model.
3533    Use ``-tpmdev help`` to print all available TPM backend types.
3535The available backends are:
3537``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
3538    (Linux-host only) Enable access to the host's TPM using the
3539    passthrough driver.
3541    ``path`` specifies the path to the host's TPM device, i.e., on a
3542    Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
3543    default ``/dev/tpm0`` is used.
3545    ``cancel-path`` specifies the path to the host TPM device's sysfs
3546    entry allowing for cancellation of an ongoing TPM command.
3547    ``cancel-path`` is optional and by default QEMU will search for the
3548    sysfs entry to use.
3550    Some notes about using the host's TPM with the passthrough driver:
3552    The TPM device accessed by the passthrough driver must not be used
3553    by any other application on the host.
3555    Since the host's firmware (BIOS/UEFI) has already initialized the
3556    TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
3557    the TPM again and may therefore not show a TPM-specific menu that
3558    would otherwise allow the user to configure the TPM, e.g., allow the
3559    user to enable/disable or activate/deactivate the TPM. Further, if
3560    TPM ownership is released from within a VM then the host's TPM will
3561    get disabled and deactivated. To enable and activate the TPM again
3562    afterwards, the host has to be rebooted and the user is required to
3563    enter the firmware's menu to enable and activate the TPM. If the TPM
3564    is left disabled and/or deactivated most TPM commands will fail.
3566    To create a passthrough TPM use the following two options:
3568    ::
3570        -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3572    Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
3573    ``tpmdev=tpm0`` in the device option.
3575``-tpmdev emulator,id=id,chardev=dev``
3576    (Linux-host only) Enable access to a TPM emulator using Unix domain
3577    socket based chardev backend.
3579    ``chardev`` specifies the unique ID of a character device backend
3580    that provides connection to the software TPM server.
3582    To create a TPM emulator backend device with chardev socket backend:
3584    ::
3586        -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3593DEFHEADING(Linux/Multiboot boot specific:)
3595When using these options, you can use a given Linux or Multiboot kernel
3596without installing it in the disk image. It can be useful for easier
3597testing of various kernels.
3602DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
3603    "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
3605``-kernel bzImage``
3606    Use bzImage as kernel image. The kernel can be either a Linux kernel
3607    or in multiboot format.
3610DEF("append", HAS_ARG, QEMU_OPTION_append, \
3611    "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
3613``-append cmdline``
3614    Use cmdline as kernel command line
3617DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
3618           "-initrd file    use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
3620``-initrd file``
3621    Use file as initial ram disk.
3623``-initrd "file1 arg=foo,file2"``
3624    This syntax is only available with multiboot.
3626    Use file1 and file2 as modules and pass arg=foo as parameter to the
3627    first module.
3630DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
3631    "-dtb    file    use 'file' as device tree image\n", QEMU_ARCH_ALL)
3633``-dtb file``
3634    Use file as a device tree binary (dtb) image and pass it to the
3635    kernel on boot.
3640DEFHEADING(Debug/Expert options:)
3642DEF("compat", HAS_ARG, QEMU_OPTION_compat,
3643    "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n"
3644    "                Policy for handling deprecated management interfaces\n"
3645    "-compat [unstable-input=accept|reject|crash][,unstable-output=accept|hide]\n"
3646    "                Policy for handling unstable management interfaces\n",
3647    QEMU_ARCH_ALL)
3649``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]``
3650    Set policy for handling deprecated management interfaces (experimental):
3652    ``deprecated-input=accept`` (default)
3653        Accept deprecated commands and arguments
3654    ``deprecated-input=reject``
3655        Reject deprecated commands and arguments
3656    ``deprecated-input=crash``
3657        Crash on deprecated commands and arguments
3658    ``deprecated-output=accept`` (default)
3659        Emit deprecated command results and events
3660    ``deprecated-output=hide``
3661        Suppress deprecated command results and events
3663    Limitation: covers only syntactic aspects of QMP.
3665``-compat [unstable-input=@var{input-policy}][,unstable-output=@var{output-policy}]``
3666    Set policy for handling unstable management interfaces (experimental):
3668    ``unstable-input=accept`` (default)
3669        Accept unstable commands and arguments
3670    ``unstable-input=reject``
3671        Reject unstable commands and arguments
3672    ``unstable-input=crash``
3673        Crash on unstable commands and arguments
3674    ``unstable-output=accept`` (default)
3675        Emit unstable command results and events
3676    ``unstable-output=hide``
3677        Suppress unstable command results and events
3679    Limitation: covers only syntactic aspects of QMP.
3682DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
3683    "-fw_cfg [name=]<name>,file=<file>\n"
3684    "                add named fw_cfg entry with contents from file\n"
3685    "-fw_cfg [name=]<name>,string=<str>\n"
3686    "                add named fw_cfg entry with contents from string\n",
3687    QEMU_ARCH_ALL)
3689``-fw_cfg [name=]name,file=file``
3690    Add named fw\_cfg entry with contents from file file.
3692``-fw_cfg [name=]name,string=str``
3693    Add named fw\_cfg entry with contents from string str.
3695    The terminating NUL character of the contents of str will not be
3696    included as part of the fw\_cfg item data. To insert contents with
3697    embedded NUL characters, you have to use the file parameter.
3699    The fw\_cfg entries are passed by QEMU through to the guest.
3701    Example:
3703    ::
3705            -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
3707    creates an fw\_cfg entry named opt/com.mycompany/blob with contents
3708    from ./my\_blob.bin.
3711DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
3712    "-serial dev     redirect the serial port to char device 'dev'\n",
3713    QEMU_ARCH_ALL)
3715``-serial dev``
3716    Redirect the virtual serial port to host character device dev. The
3717    default device is ``vc`` in graphical mode and ``stdio`` in non
3718    graphical mode.
3720    This option can be used several times to simulate up to 4 serial
3721    ports.
3723    Use ``-serial none`` to disable all serial ports.
3725    Available character devices are:
3727    ``vc[:WxH]``
3728        Virtual console. Optionally, a width and height can be given in
3729        pixel with
3731        ::
3733            vc:800x600
3735        It is also possible to specify width or height in characters:
3737        ::
3739            vc:80Cx24C
3741    ``pty``
3742        [Linux only] Pseudo TTY (a new PTY is automatically allocated)
3744    ``none``
3745        No device is allocated.
3747    ``null``
3748        void device
3750    ``chardev:id``
3751        Use a named character device defined with the ``-chardev``
3752        option.
3754    ``/dev/XXX``
3755        [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
3756        port parameters are set according to the emulated ones.
3758    ``/dev/parportN``
3759        [Linux only, parallel port only] Use host parallel port N.
3760        Currently SPP and EPP parallel port features can be used.
3762    ``file:filename``
3763        Write output to filename. No character can be read.
3765    ``stdio``
3766        [Unix only] standard input/output
3768    ``pipe:filename``
3769        name pipe filename
3771    ``COMn``
3772        [Windows only] Use host serial port n
3774    ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
3775        This implements UDP Net Console. When remote\_host or src\_ip
3776        are not specified they default to ````. When not using a
3777        specified src\_port a random port is automatically chosen.
3779        If you just want a simple readonly console you can use
3780        ``netcat`` or ``nc``, by starting QEMU with:
3781        ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
3782        QEMU writes something to that port it will appear in the
3783        netconsole session.
3785        If you plan to send characters back via netconsole or you want
3786        to stop and start QEMU a lot of times, you should have QEMU use
3787        the same source port each time by using something like ``-serial
3788        udp::4555@:4556`` to QEMU. Another approach is to use a patched
3789        version of netcat which can listen to a TCP port and send and
3790        receive characters via udp. If you have a patched version of
3791        netcat which activates telnet remote echo and single char
3792        transfer, then you can use the following options to set up a
3793        netcat redirector to allow telnet on port 5555 to access the
3794        QEMU port.
3796        ``QEMU Options:``
3797            -serial udp::4555@:4556
3799        ``netcat options:``
3800            -u -P 4555 -L -t -p 5555 -I -T
3802        ``telnet options:``
3803            localhost 5555
3805    ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]``
3806        The TCP Net Console has two modes of operation. It can send the
3807        serial I/O to a location or wait for a connection from a
3808        location. By default the TCP Net Console is sent to host at the
3809        port. If you use the ``server=on`` option QEMU will wait for a client
3810        socket application to connect to the port before continuing,
3811        unless the ``wait=on|off`` option was specified. The ``nodelay=on|off``
3812        option disables the Nagle buffering algorithm. The ``reconnect=on``
3813        option only applies if ``server=no`` is set, if the connection goes
3814        down it will attempt to reconnect at the given interval. If host
3815        is omitted, is assumed. Only one TCP connection at a
3816        time is accepted. You can use ``telnet=on`` to connect to the
3817        corresponding character device.
3819        ``Example to send tcp console to port 4444``
3820            -serial tcp:
3822        ``Example to listen and wait on port 4444 for connection``
3823            -serial tcp::4444,server=on
3825        ``Example to not wait and listen on ip port 4444``
3826            -serial tcp:,server=on,wait=off
3828    ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]``
3829        The telnet protocol is used instead of raw tcp sockets. The
3830        options work the same as if you had specified ``-serial tcp``.
3831        The difference is that the port acts like a telnet server or
3832        client using telnet option negotiation. This will also allow you
3833        to send the MAGIC\_SYSRQ sequence if you use a telnet that
3834        supports sending the break sequence. Typically in unix telnet
3835        you do it with Control-] and then type "send break" followed by
3836        pressing the enter key.
3838    ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]``
3839        The WebSocket protocol is used instead of raw tcp socket. The
3840        port acts as a WebSocket server. Client mode is not supported.
3842    ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]``
3843        A unix domain socket is used instead of a tcp socket. The option
3844        works the same as if you had specified ``-serial tcp`` except
3845        the unix domain socket path is used for connections.
3847    ``mon:dev_string``
3848        This is a special option to allow the monitor to be multiplexed
3849        onto another serial port. The monitor is accessed with key
3850        sequence of Control-a and then pressing c. dev\_string should be
3851        any one of the serial devices specified above. An example to
3852        multiplex the monitor onto a telnet server listening on port
3853        4444 would be:
3855        ``-serial mon:telnet::4444,server=on,wait=off``
3857        When the monitor is multiplexed to stdio in this way, Ctrl+C
3858        will not terminate QEMU any more but will be passed to the guest
3859        instead.
3861    ``braille``
3862        Braille device. This will use BrlAPI to display the braille
3863        output on a real or fake device.
3865    ``msmouse``
3866        Three button serial mouse. Configure the guest to use Microsoft
3867        protocol.
3870DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
3871    "-parallel dev   redirect the parallel port to char device 'dev'\n",
3872    QEMU_ARCH_ALL)
3874``-parallel dev``
3875    Redirect the virtual parallel port to host device dev (same devices
3876    as the serial port). On Linux hosts, ``/dev/parportN`` can be used
3877    to use hardware devices connected on the corresponding host parallel
3878    port.
3880    This option can be used several times to simulate up to 3 parallel
3881    ports.
3883    Use ``-parallel none`` to disable all parallel ports.
3886DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
3887    "-monitor dev    redirect the monitor to char device 'dev'\n",
3888    QEMU_ARCH_ALL)
3890``-monitor dev``
3891    Redirect the monitor to host device dev (same devices as the serial
3892    port). The default device is ``vc`` in graphical mode and ``stdio``
3893    in non graphical mode. Use ``-monitor none`` to disable the default
3894    monitor.
3896DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
3897    "-qmp dev        like -monitor but opens in 'control' mode\n",
3898    QEMU_ARCH_ALL)
3900``-qmp dev``
3901    Like -monitor but opens in 'control' mode.
3903DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
3904    "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
3905    QEMU_ARCH_ALL)
3907``-qmp-pretty dev``
3908    Like -qmp but uses pretty JSON formatting.
3911DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
3912    "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
3914``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
3915    Setup monitor on chardev name. ``mode=control`` configures 
3916    a QMP monitor (a JSON RPC-style protocol) and it is not the
3917    same as HMP, the human monitor that has a "(qemu)" prompt.
3918    ``pretty`` is only valid when ``mode=control``, 
3919    turning on JSON pretty printing to ease
3920    human reading and debugging.
3923DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
3924    "-debugcon dev   redirect the debug console to char device 'dev'\n",
3925    QEMU_ARCH_ALL)
3927``-debugcon dev``
3928    Redirect the debug console to host device dev (same devices as the
3929    serial port). The debug console is an I/O port which is typically
3930    port 0xe9; writing to that I/O port sends output to this device. The
3931    default device is ``vc`` in graphical mode and ``stdio`` in non
3932    graphical mode.
3935DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
3936    "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
3938``-pidfile file``
3939    Store the QEMU process PID in file. It is useful if you launch QEMU
3940    from a script.
3943DEF("singlestep", 0, QEMU_OPTION_singlestep, \
3944    "-singlestep     always run in singlestep mode\n", QEMU_ARCH_ALL)
3947    Run the emulation in single step mode.
3950DEF("preconfig", 0, QEMU_OPTION_preconfig, \
3951    "--preconfig     pause QEMU before machine is initialized (experimental)\n",
3952    QEMU_ARCH_ALL)
3955    Pause QEMU for interactive configuration before the machine is
3956    created, which allows querying and configuring properties that will
3957    affect machine initialization. Use QMP command 'x-exit-preconfig' to
3958    exit the preconfig state and move to the next state (i.e. run guest
3959    if -S isn't used or pause the second time if -S is used). This
3960    option is experimental.
3963DEF("S", 0, QEMU_OPTION_S, \
3964    "-S              freeze CPU at startup (use 'c' to start execution)\n",
3965    QEMU_ARCH_ALL)
3968    Do not start CPU at startup (you must type 'c' in the monitor).
3971DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
3972    "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
3973    "                run qemu with overcommit hints\n"
3974    "                mem-lock=on|off controls memory lock support (default: off)\n"
3975    "                cpu-pm=on|off controls cpu power management (default: off)\n",
3976    QEMU_ARCH_ALL)
3978``-overcommit mem-lock=on|off``
3979  \ 
3980``-overcommit cpu-pm=on|off``
3981    Run qemu with hints about host resource overcommit. The default is
3982    to assume that host overcommits all resources.
3984    Locking qemu and guest memory can be enabled via ``mem-lock=on``
3985    (disabled by default). This works when host memory is not
3986    overcommitted and reduces the worst-case latency for guest.
3988    Guest ability to manage power state of host cpus (increasing latency
3989    for other processes on the same host cpu, but decreasing latency for
3990    guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
3991    works best when host CPU is not overcommitted. When used, host
3992    estimates of CPU cycle and power utilization will be incorrect, not
3993    taking into account guest idle time.
3996DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
3997    "-gdb dev        accept gdb connection on 'dev'. (QEMU defaults to starting\n"
3998    "                the guest without waiting for gdb to connect; use -S too\n"
3999    "                if you want it to not start execution.)\n",
4000    QEMU_ARCH_ALL)
4002``-gdb dev``
4003    Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter
4004    in the System Emulation Users Guide). Note that this option does not pause QEMU
4005    execution -- if you want QEMU to not start the guest until you
4006    connect with gdb and issue a ``continue`` command, you will need to
4007    also pass the ``-S`` option to QEMU.
4009    The most usual configuration is to listen on a local TCP socket::
4011        -gdb tcp::3117
4013    but you can specify other backends; UDP, pseudo TTY, or even stdio
4014    are all reasonable use cases. For example, a stdio connection
4015    allows you to start QEMU from within gdb and establish the
4016    connection via a pipe:
4018    .. parsed-literal::
4020        (gdb) target remote | exec |qemu_system| -gdb stdio ...
4023DEF("s", 0, QEMU_OPTION_s, \
4024    "-s              shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
4025    QEMU_ARCH_ALL)
4028    Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
4029    (see the :ref:`GDB usage` chapter in the System Emulation Users Guide).
4032DEF("d", HAS_ARG, QEMU_OPTION_d, \
4033    "-d item1,...    enable logging of specified items (use '-d help' for a list of log items)\n",
4034    QEMU_ARCH_ALL)
4036``-d item1[,...]``
4037    Enable logging of specified items. Use '-d help' for a list of log
4038    items.
4042    "-D logfile      output log to logfile (default stderr)\n",
4043    QEMU_ARCH_ALL)
4045``-D logfile``
4046    Output log in logfile instead of to stderr
4050    "-dfilter range,..  filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
4051    QEMU_ARCH_ALL)
4053``-dfilter range1[,...]``
4054    Filter debug output to that relevant to a range of target addresses.
4055    The filter spec can be either start+size, start-size or start..end
4056    where start end and size are the addresses and sizes required. For
4057    example:
4059    ::
4061            -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
4063    Will dump output for any code in the 0x1000 sized block starting at
4064    0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
4065    another 0x1000 sized block starting at 0xffffffc00005f000.
4068DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
4069    "-seed number       seed the pseudo-random number generator\n",
4070    QEMU_ARCH_ALL)
4072``-seed number``
4073    Force the guest to use a deterministic pseudo-random number
4074    generator, seeded with number. This does not affect crypto routines
4075    within the host.
4079    "-L path         set the directory for the BIOS, VGA BIOS and keymaps\n",
4080    QEMU_ARCH_ALL)
4082``-L  path``
4083    Set the directory for the BIOS, VGA BIOS and keymaps.
4085    To list all the data directories, use ``-L help``.
4088DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
4089    "-bios file      set the filename for the BIOS\n", QEMU_ARCH_ALL)
4091``-bios file``
4092    Set the filename for the BIOS.
4095DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
4096    "-enable-kvm     enable KVM full virtualization support\n", QEMU_ARCH_ALL)
4099    Enable KVM full virtualization support. This option is only
4100    available if KVM support is enabled when compiling.
4103DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
4104    "-xen-domid id   specify xen guest domain id\n", QEMU_ARCH_ALL)
4105DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
4106    "-xen-attach     attach to existing xen domain\n"
4107    "                libxl will use this when starting QEMU\n",
4108    QEMU_ARCH_ALL)
4109DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
4110    "-xen-domid-restrict     restrict set of available xen operations\n"
4111    "                        to specified domain id. (Does not affect\n"
4112    "                        xenpv machine type).\n",
4113    QEMU_ARCH_ALL)
4115``-xen-domid id``
4116    Specify xen guest domain id (XEN only).
4119    Attach to existing xen domain. libxl will use this when starting
4120    QEMU (XEN only). Restrict set of available xen operations to
4121    specified domain id (XEN only).
4124DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
4125    "-no-reboot      exit instead of rebooting\n", QEMU_ARCH_ALL)
4128    Exit instead of rebooting.
4131DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
4132    "-no-shutdown    stop before shutdown\n", QEMU_ARCH_ALL)
4135    Don't exit QEMU on guest shutdown, but instead only stop the
4136    emulation. This allows for instance switching to monitor to commit
4137    changes to the disk image.
4140DEF("action", HAS_ARG, QEMU_OPTION_action,
4141    "-action reboot=reset|shutdown\n"
4142    "                   action when guest reboots [default=reset]\n"
4143    "-action shutdown=poweroff|pause\n"
4144    "                   action when guest shuts down [default=poweroff]\n"
4145    "-action panic=pause|shutdown|none\n"
4146    "                   action when guest panics [default=shutdown]\n"
4147    "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
4148    "                   action when watchdog fires [default=reset]\n",
4149    QEMU_ARCH_ALL)
4151``-action event=action``
4152    The action parameter serves to modify QEMU's default behavior when
4153    certain guest events occur. It provides a generic method for specifying the
4154    same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown``
4155    parameters.
4157    Examples:
4159    ``-action panic=none``
4160    ``-action reboot=shutdown,shutdown=pause``
4161    ``-watchdog i6300esb -action watchdog=pause``
4165DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
4166    "-loadvm [tag|id]\n" \
4167    "                start right away with a saved state (loadvm in monitor)\n",
4168    QEMU_ARCH_ALL)
4170``-loadvm file``
4171    Start right away with a saved state (``loadvm`` in monitor)
4174#ifndef _WIN32
4175DEF("daemonize", 0, QEMU_OPTION_daemonize, \
4176    "-daemonize      daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
4180    Daemonize the QEMU process after initialization. QEMU will not
4181    detach from standard IO until it is ready to receive connections on
4182    any of its devices. This option is a useful way for external
4183    programs to launch QEMU without having to cope with initialization
4184    race conditions.
4187DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
4188    "-option-rom rom load a file, rom, into the option ROM space\n",
4189    QEMU_ARCH_ALL)
4191``-option-rom file``
4192    Load the contents of file as an option ROM. This option is useful to
4193    load things like EtherBoot.
4196DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
4197    "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
4198    "                set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
4199    QEMU_ARCH_ALL)
4202``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
4203    Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
4204    the current UTC or local time, respectively. ``localtime`` is
4205    required for correct date in MS-DOS or Windows. To start at a
4206    specific point in time, provide datetime in the format
4207    ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.
4209    By default the RTC is driven by the host system time. This allows
4210    using of the RTC as accurate reference clock inside the guest,
4211    specifically if the host time is smoothly following an accurate
4212    external reference clock, e.g. via NTP. If you want to isolate the
4213    guest time from the host, you can set ``clock`` to ``rt`` instead,
4214    which provides a host monotonic clock if host support it. To even
4215    prevent the RTC from progressing during suspension, you can set
4216    ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
4217    recommended especially in icount mode in order to preserve
4218    determinism; however, note that in icount mode the speed of the
4219    virtual clock is variable and can in general differ from the host
4220    clock.
4222    Enable ``driftfix`` (i386 targets only) if you experience time drift
4223    problems, specifically with Windows' ACPI HAL. This option will try
4224    to figure out how many timer interrupts were not processed by the
4225    Windows guest and will re-inject them.
4228DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
4229    "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \
4230    "                enable virtual instruction counter with 2^N clock ticks per\n" \
4231    "                instruction, enable aligning the host and virtual clocks\n" \
4232    "                or disable real time cpu sleeping, and optionally enable\n" \
4233    "                record-and-replay mode\n", QEMU_ARCH_ALL)
4235``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]``
4236    Enable virtual instruction counter. The virtual cpu will execute one
4237    instruction every 2^N ns of virtual time. If ``auto`` is specified
4238    then the virtual cpu speed will be automatically adjusted to keep
4239    virtual time within a few seconds of real time.
4241    Note that while this option can give deterministic behavior, it does
4242    not provide cycle accurate emulation. Modern CPUs contain
4243    superscalar out of order cores with complex cache hierarchies. The
4244    number of instructions executed often has little or no correlation
4245    with actual performance.
4247    When the virtual cpu is sleeping, the virtual time will advance at
4248    default speed unless ``sleep=on`` is specified. With
4249    ``sleep=on``, the virtual time will jump to the next timer
4250    deadline instantly whenever the virtual cpu goes to sleep mode and
4251    will not advance if no timer is enabled. This behavior gives
4252    deterministic execution times from the guest point of view.
4253    The default if icount is enabled is ``sleep=off``.
4254    ``sleep=on`` cannot be used together with either ``shift=auto``
4255    or ``align=on``.
4257    ``align=on`` will activate the delay algorithm which will try to
4258    synchronise the host clock and the virtual clock. The goal is to
4259    have a guest running at the real frequency imposed by the shift
4260    option. Whenever the guest clock is behind the host clock and if
4261    ``align=on`` is specified then we print a message to the user to
4262    inform about the delay. Currently this option does not work when
4263    ``shift`` is ``auto``. Note: The sync algorithm will work for those
4264    shift values for which the guest clock runs ahead of the host clock.
4265    Typically this happens when the shift value is high (how high
4266    depends on the host machine). The default if icount is enabled
4267    is ``align=off``.
4269    When the ``rr`` option is specified deterministic record/replay is
4270    enabled. The ``rrfile=`` option must also be provided to
4271    specify the path to the replay log. In record mode data is written
4272    to this file, and in replay mode it is read back.
4273    If the ``rrsnapshot`` option is given then it specifies a VM snapshot
4274    name. In record mode, a new VM snapshot with the given name is created
4275    at the start of execution recording. In replay mode this option
4276    specifies the snapshot name used to load the initial VM state.
4279DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
4280    "-watchdog model\n" \
4281    "                enable virtual hardware watchdog [default=none]\n",
4282    QEMU_ARCH_ALL)
4284``-watchdog model``
4285    Create a virtual hardware watchdog device. Once enabled (by a guest
4286    action), the watchdog must be periodically polled by an agent inside
4287    the guest or else the guest will be restarted. Choose a model for
4288    which your guest has drivers.
4290    The model is the model of hardware watchdog to emulate. Use
4291    ``-watchdog help`` to list available hardware models. Only one
4292    watchdog can be enabled for a guest.
4294    The following models may be available:
4296    ``ib700``
4297        iBASE 700 is a very simple ISA watchdog with a single timer.
4299    ``i6300esb``
4300        Intel 6300ESB I/O controller hub is a much more featureful
4301        PCI-based dual-timer watchdog.
4303    ``diag288``
4304        A virtual watchdog for s390x backed by the diagnose 288
4305        hypercall (currently KVM only).
4308DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
4309    "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
4310    "                action when watchdog fires [default=reset]\n",
4311    QEMU_ARCH_ALL)
4313``-watchdog-action action``
4314    The action controls what QEMU will do when the watchdog timer
4315    expires. The default is ``reset`` (forcefully reset the guest).
4316    Other possible actions are: ``shutdown`` (attempt to gracefully
4317    shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
4318    ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
4319    guest), ``debug`` (print a debug message and continue), or ``none``
4320    (do nothing).
4322    Note that the ``shutdown`` action requires that the guest responds
4323    to ACPI signals, which it may not be able to do in the sort of
4324    situations where the watchdog would have expired, and thus
4325    ``-watchdog-action shutdown`` is not recommended for production use.
4327    Examples:
4329    ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700``
4333DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
4334    "-echr chr       set terminal escape character instead of ctrl-a\n",
4335    QEMU_ARCH_ALL)
4337``-echr numeric_ascii_value``
4338    Change the escape character used for switching to the monitor when
4339    using monitor and serial sharing. The default is ``0x01`` when using
4340    the ``-nographic`` option. ``0x01`` is equal to pressing
4341    ``Control-a``. You can select a different character from the ascii
4342    control keys where 1 through 26 map to Control-a through Control-z.
4343    For instance you could use the either of the following to change the
4344    escape character to Control-t.
4346    ``-echr 0x14``; \ ``-echr 20``
4350DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
4351    "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \
4352    "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \
4353    "-incoming unix:socketpath\n" \
4354    "                prepare for incoming migration, listen on\n" \
4355    "                specified protocol and socket address\n" \
4356    "-incoming fd:fd\n" \
4357    "-incoming exec:cmdline\n" \
4358    "                accept incoming migration on given file descriptor\n" \
4359    "                or from given external command\n" \
4360    "-incoming defer\n" \
4361    "                wait for the URI to be specified via migrate_incoming\n",
4362    QEMU_ARCH_ALL)
4364``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]``
4365  \ 
4366``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]``
4367    Prepare for incoming migration, listen on a given tcp port.
4369``-incoming unix:socketpath``
4370    Prepare for incoming migration, listen on a given unix socket.
4372``-incoming fd:fd``
4373    Accept incoming migration from a given filedescriptor.
4375``-incoming exec:cmdline``
4376    Accept incoming migration as an output from specified external
4377    command.
4379``-incoming defer``
4380    Wait for the URI to be specified via migrate\_incoming. The monitor
4381    can be used to change settings (such as migration parameters) prior
4382    to issuing the migrate\_incoming to allow the migration to begin.
4385DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
4386    "-only-migratable     allow only migratable devices\n", QEMU_ARCH_ALL)
4389    Only allow migratable devices. Devices will not be allowed to enter
4390    an unmigratable state.
4393DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
4394    "-nodefaults     don't create default devices\n", QEMU_ARCH_ALL)
4397    Don't create default devices. Normally, QEMU sets the default
4398    devices like serial port, parallel port, virtual console, monitor
4399    device, VGA adapter, floppy and CD-ROM drive and others. The
4400    ``-nodefaults`` option will disable all those default devices.
4403#ifndef _WIN32
4404DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
4405    "-chroot dir     chroot to dir just before starting the VM\n",
4406    QEMU_ARCH_ALL)
4409``-chroot dir``
4410    Immediately before starting guest execution, chroot to the specified
4411    directory. Especially useful in combination with -runas.
4414#ifndef _WIN32
4415DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
4416    "-runas user     change to user id user just before starting the VM\n" \
4417    "                user can be numeric uid:gid instead\n",
4418    QEMU_ARCH_ALL)
4421``-runas user``
4422    Immediately before starting guest execution, drop root privileges,
4423    switching to the specified user.
4426DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
4427    "-prom-env variable=value\n"
4428    "                set OpenBIOS nvram variables\n",
4431``-prom-env variable=value``
4432    Set OpenBIOS nvram variable to given value (PPC, SPARC only).
4434    ::
4436        qemu-system-sparc -prom-env 'auto-boot?=false' \
4437         -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
4439    ::
4441        qemu-system-ppc -prom-env 'auto-boot?=false' \
4442         -prom-env 'boot-device=hd:2,\yaboot' \
4443         -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
4445DEF("semihosting", 0, QEMU_OPTION_semihosting,
4446    "-semihosting    semihosting mode\n",
4451    Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only).
4453    Note that this allows guest direct access to the host filesystem, so
4454    should only be used with a trusted guest OS.
4456    See the -semihosting-config option documentation for further
4457    information about the facilities this enables.
4459DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
4460    "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
4461    "                semihosting configuration\n",
4465``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]``
4466    Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V
4467    only).
4469    Note that this allows guest direct access to the host filesystem, so
4470    should only be used with a trusted guest OS.
4472    On Arm this implements the standard semihosting API, version 2.0.
4474    On M68K this implements the "ColdFire GDB" interface used by
4475    libgloss.
4477    Xtensa semihosting provides basic file IO calls, such as
4478    open/read/write/seek/select. Tensilica baremetal libc for ISS and
4479    linux platform "sim" use this interface.
4481    On RISC-V this implements the standard semihosting API, version 0.2.
4483    ``target=native|gdb|auto``
4484        Defines where the semihosting calls will be addressed, to QEMU
4485        (``native``) or to GDB (``gdb``). The default is ``auto``, which
4486        means ``gdb`` during debug sessions and ``native`` otherwise.
4488    ``chardev=str1``
4489        Send the output to a chardev backend output for native or auto
4490        output when not in gdb
4492    ``arg=str1,arg=str2,...``
4493        Allows the user to pass input arguments, and can be used
4494        multiple times to build up a list. The old-style
4495        ``-kernel``/``-append`` method of passing a command line is
4496        still supported for backward compatibility. If both the
4497        ``--semihosting-config arg`` and the ``-kernel``/``-append`` are
4498        specified, the former is passed to semihosting as it always
4499        takes precedence.
4501DEF("old-param", 0, QEMU_OPTION_old_param,
4502    "-old-param      old param mode\n", QEMU_ARCH_ARM)
4505    Old param mode (ARM only).
4508DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
4509    "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4510    "          [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4511    "                Enable seccomp mode 2 system call filter (default 'off').\n" \
4512    "                use 'obsolete' to allow obsolete system calls that are provided\n" \
4513    "                    by the kernel, but typically no longer used by modern\n" \
4514    "                    C library implementations.\n" \
4515    "                use 'elevateprivileges' to allow or deny the QEMU process ability\n" \
4516    "                    to elevate privileges using set*uid|gid system calls.\n" \
4517    "                    The value 'children' will deny set*uid|gid system calls for\n" \
4518    "                    main QEMU process but will allow forks and execves to run unprivileged\n" \
4519    "                use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4520    "                     blocking *fork and execve\n" \
4521    "                use 'resourcecontrol' to disable process affinity and schedular priority\n",
4522    QEMU_ARCH_ALL)
4524``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]``
4525    Enable Seccomp mode 2 system call filter. 'on' will enable syscall
4526    filtering and 'off' will disable it. The default is 'off'.
4528    ``obsolete=string``
4529        Enable Obsolete system calls
4531    ``elevateprivileges=string``
4532        Disable set\*uid\|gid system calls
4534    ``spawn=string``
4535        Disable \*fork and execve
4537    ``resourcecontrol=string``
4538        Disable process affinity and schedular priority
4541DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
4542    "-readconfig <file>\n", QEMU_ARCH_ALL)
4544``-readconfig file``
4545    Read device configuration from file. This approach is useful when
4546    you want to spawn QEMU process with many command line options but
4547    you don't want to exceed the command line character limit.
4549DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
4550    "-writeconfig <file>\n"
4551    "                read/write config file (deprecated)\n", QEMU_ARCH_ALL)
4555DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4556    "-no-user-config\n"
4557    "                do not load default user-provided config files at startup\n",
4558    QEMU_ARCH_ALL)
4561    The ``-no-user-config`` option makes QEMU not load any of the
4562    user-provided config files on sysconfdir.
4565DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4566    "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4567    "                specify tracing options\n",
4568    QEMU_ARCH_ALL)
4570``-trace [[enable=]pattern][,events=file][,file=file]``
4571  .. include:: ../qemu-option-trace.rst.inc
4574DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4575    "-plugin [file=]<file>[,<argname>=<argvalue>]\n"
4576    "                load a plugin\n",
4577    QEMU_ARCH_ALL)
4579``-plugin file=file[,argname=argvalue]``
4580    Load a plugin.
4582    ``file=file``
4583        Load the given plugin from a shared library file.
4585    ``argname=argvalue``
4586        Argument passed to the plugin. (Can be given multiple times.)
4589HXCOMM Internal use
4590DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4591DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4593#ifdef __linux__
4594DEF("enable-fips", 0, QEMU_OPTION_enablefips,
4595    "-enable-fips    enable FIPS 140-2 compliance\n",
4596    QEMU_ARCH_ALL)
4600    Enable FIPS 140-2 compliance mode.
4603DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4604    "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
4605    "                control error message format\n"
4606    "                timestamp=on enables timestamps (default: off)\n"
4607    "                guest-name=on enables guest name prefix but only if\n"
4608    "                              -name guest option is set (default: off)\n",
4609    QEMU_ARCH_ALL)
4611``-msg [timestamp[=on|off]][,guest-name[=on|off]]``
4612    Control error message format.
4614    ``timestamp=on|off``
4615        Prefix messages with a timestamp. Default is off.
4617    ``guest-name=on|off``
4618        Prefix messages with guest name but only if -name guest option is set
4619        otherwise the option is ignored. Default is off.
4622DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
4623    "-dump-vmstate <file>\n"
4624    "                Output vmstate information in JSON format to file.\n"
4625    "                Use the scripts/vmstate-static-checker.py file to\n"
4626    "                check for possible regressions in migration code\n"
4627    "                by comparing two such vmstate dumps.\n",
4628    QEMU_ARCH_ALL)
4630``-dump-vmstate file``
4631    Dump json-encoded vmstate information for current machine type to
4632    file in file
4635DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
4636    "-enable-sync-profile\n"
4637    "                enable synchronization profiling\n",
4638    QEMU_ARCH_ALL)
4641    Enable synchronization profiling.
4646DEFHEADING(Generic object creation:)
4648DEF("object", HAS_ARG, QEMU_OPTION_object,
4649    "-object TYPENAME[,PROP1=VALUE1,...]\n"
4650    "                create a new object of type TYPENAME setting properties\n"
4651    "                in the order they are specified.  Note that the 'id'\n"
4652    "                property must be set.  These objects are placed in the\n"
4653    "                '/objects' path.\n",
4654    QEMU_ARCH_ALL)
4656``-object typename[,prop1=value1,...]``
4657    Create a new object of type typename setting properties in the order
4658    they are specified. Note that the 'id' property must be set. These
4659    objects are placed in the '/objects' path.
4661    ``-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``
4662        Creates a memory file backend object, which can be used to back
4663        the guest RAM with huge pages.
4665        The ``id`` parameter is a unique ID that will be used to
4666        reference this memory region in other parameters, e.g. ``-numa``,
4667        ``-device nvdimm``, etc.
4669        The ``size`` option provides the size of the memory region, and
4670        accepts common suffixes, e.g. ``500M``.
4672        The ``mem-path`` provides the path to either a shared memory or
4673        huge page filesystem mount.
4675        The ``share`` boolean option determines whether the memory
4676        region is marked as private to QEMU, or shared. The latter
4677        allows a co-operating external process to access the QEMU memory
4678        region.
4680        The ``share`` is also required for pvrdma devices due to
4681        limitations in the RDMA API provided by Linux.
4683        Setting share=on might affect the ability to configure NUMA
4684        bindings for the memory backend under some circumstances, see
4685        Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
4686        source tree for additional details.
4688        Setting the ``discard-data`` boolean option to on indicates that
4689        file contents can be destroyed when QEMU exits, to avoid
4690        unnecessarily flushing data to the backing file. Note that
4691        ``discard-data`` is only an optimization, and QEMU might not
4692        discard file contents if it aborts unexpectedly or is terminated
4693        using SIGKILL.
4695        The ``merge`` boolean option enables memory merge, also known as
4696        MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
4697        the pages for memory deduplication.
4699        Setting the ``dump`` boolean option to off excludes the memory
4700        from core dumps. This feature is also known as MADV\_DONTDUMP.
4702        The ``prealloc`` boolean option enables memory preallocation.
4704        The ``host-nodes`` option binds the memory range to a list of
4705        NUMA host nodes.
4707        The ``policy`` option sets the NUMA policy to one of the
4708        following values:
4710        ``default``
4711            default host policy
4713        ``preferred``
4714            prefer the given host node list for allocation
4716        ``bind``
4717            restrict memory allocation to the given host node list
4719        ``interleave``
4720            interleave memory allocations across the given host node
4721            list
4723        The ``align`` option specifies the base address alignment when
4724        QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
4725        ``2M``. Some backend store specified by ``mem-path`` requires an
4726        alignment different than the default one used by QEMU, eg the
4727        device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
4728        such cases, users can specify the required alignment via this
4729        option.
4731        The ``pmem`` option specifies whether the backing file specified
4732        by ``mem-path`` is in host persistent memory that can be
4733        accessed using the SNIA NVM programming model (e.g. Intel
4734        NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary
4735        operations to guarantee the persistence of its own writes to
4736        ``mem-path`` (e.g. in vNVDIMM label emulation and live
4737        migration). Also, we will map the backend-file with MAP\_SYNC
4738        flag, which ensures the file metadata is in sync for
4739        ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
4740        requires support from both the host kernel (since Linux kernel
4741        4.15) and the filesystem of ``mem-path`` mounted with DAX
4742        option.
4744        The ``readonly`` option specifies whether the backing file is opened
4745        read-only or read-write (default).
4747    ``-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``
4748        Creates a memory backend object, which can be used to back the
4749        guest RAM. Memory backend objects offer more control than the
4750        ``-m`` option that is traditionally used to define guest RAM.
4751        Please refer to ``memory-backend-file`` for a description of the
4752        options.
4754    ``-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``
4755        Creates an anonymous memory file backend object, which allows
4756        QEMU to share the memory with an external process (e.g. when
4757        using vhost-user). The memory is allocated with memfd and
4758        optional sealing. (Linux only)
4760        The ``seal`` option creates a sealed-file, that will block
4761        further resizing the memory ('on' by default).
4763        The ``hugetlb`` option specify the file to be created resides in
4764        the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
4765        with the ``hugetlb`` option, the ``hugetlbsize`` option specify
4766        the hugetlb page size on systems that support multiple hugetlb
4767        page sizes (it must be a power of 2 value supported by the
4768        system).
4770        In some versions of Linux, the ``hugetlb`` option is
4771        incompatible with the ``seal`` option (requires at least Linux
4772        4.16).
4774        Please refer to ``memory-backend-file`` for a description of the
4775        other options.
4777        The ``share`` boolean option is on by default with memfd.
4779    ``-object rng-builtin,id=id``
4780        Creates a random number generator backend which obtains entropy
4781        from QEMU builtin functions. The ``id`` parameter is a unique ID
4782        that will be used to reference this entropy backend from the
4783        ``virtio-rng`` device. By default, the ``virtio-rng`` device
4784        uses this RNG backend.
4786    ``-object rng-random,id=id,filename=/dev/random``
4787        Creates a random number generator backend which obtains entropy
4788        from a device on the host. The ``id`` parameter is a unique ID
4789        that will be used to reference this entropy backend from the
4790        ``virtio-rng`` device. The ``filename`` parameter specifies
4791        which file to obtain entropy from and if omitted defaults to
4792        ``/dev/urandom``.
4794    ``-object rng-egd,id=id,chardev=chardevid``
4795        Creates a random number generator backend which obtains entropy
4796        from an external daemon running on the host. The ``id``
4797        parameter is a unique ID that will be used to reference this
4798        entropy backend from the ``virtio-rng`` device. The ``chardev``
4799        parameter is the unique ID of a character device backend that
4800        provides the connection to the RNG daemon.
4802    ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
4803        Creates a TLS anonymous credentials object, which can be used to
4804        provide TLS support on network backends. The ``id`` parameter is
4805        a unique ID which network backends will use to access the
4806        credentials. The ``endpoint`` is either ``server`` or ``client``
4807        depending on whether the QEMU network backend that uses the
4808        credentials will be acting as a client or as a server. If
4809        ``verify-peer`` is enabled (the default) then once the handshake
4810        is completed, the peer credentials will be verified, though this
4811        is a no-op for anonymous credentials.
4813        The dir parameter tells QEMU where to find the credential files.
4814        For server endpoints, this directory may contain a file
4815        dh-params.pem providing diffie-hellman parameters to use for the
4816        TLS server. If the file is missing, QEMU will generate a set of
4817        DH parameters at startup. This is a computationally expensive
4818        operation that consumes random pool entropy, so it is
4819        recommended that a persistent set of parameters be generated
4820        upfront and saved.
4822    ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
4823        Creates a TLS Pre-Shared Keys (PSK) credentials object, which
4824        can be used to provide TLS support on network backends. The
4825        ``id`` parameter is a unique ID which network backends will use
4826        to access the credentials. The ``endpoint`` is either ``server``
4827        or ``client`` depending on whether the QEMU network backend that
4828        uses the credentials will be acting as a client or as a server.
4829        For clients only, ``username`` is the username which will be
4830        sent to the server. If omitted it defaults to "qemu".
4832        The dir parameter tells QEMU where to find the keys file. It is
4833        called "dir/keys.psk" and contains "username:key" pairs. This
4834        file can most easily be created using the GnuTLS ``psktool``
4835        program.
4837        For server endpoints, dir may also contain a file dh-params.pem
4838        providing diffie-hellman parameters to use for the TLS server.
4839        If the file is missing, QEMU will generate a set of DH
4840        parameters at startup. This is a computationally expensive
4841        operation that consumes random pool entropy, so it is
4842        recommended that a persistent set of parameters be generated up
4843        front and saved.
4845    ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
4846        Creates a TLS anonymous credentials object, which can be used to
4847        provide TLS support on network backends. The ``id`` parameter is
4848        a unique ID which network backends will use to access the
4849        credentials. The ``endpoint`` is either ``server`` or ``client``
4850        depending on whether the QEMU network backend that uses the
4851        credentials will be acting as a client or as a server. If
4852        ``verify-peer`` is enabled (the default) then once the handshake
4853        is completed, the peer credentials will be verified. With x509
4854        certificates, this implies that the clients must be provided
4855        with valid client certificates too.
4857        The dir parameter tells QEMU where to find the credential files.
4858        For server endpoints, this directory may contain a file
4859        dh-params.pem providing diffie-hellman parameters to use for the
4860        TLS server. If the file is missing, QEMU will generate a set of
4861        DH parameters at startup. This is a computationally expensive
4862        operation that consumes random pool entropy, so it is
4863        recommended that a persistent set of parameters be generated
4864        upfront and saved.
4866        For x509 certificate credentials the directory will contain
4867        further files providing the x509 certificates. The certificates
4868        must be stored in PEM format, in filenames ca-cert.pem,
4869        ca-crl.pem (optional), server-cert.pem (only servers),
4870        server-key.pem (only servers), client-cert.pem (only clients),
4871        and client-key.pem (only clients).
4873        For the server-key.pem and client-key.pem files which contain
4874        sensitive private keys, it is possible to use an encrypted
4875        version by providing the passwordid parameter. This provides the
4876        ID of a previously created ``secret`` object containing the
4877        password for decryption.
4879        The priority parameter allows to override the global default
4880        priority used by gnutls. This can be useful if the system
4881        administrator needs to use a weaker set of crypto priorities for
4882        QEMU without potentially forcing the weakness onto all
4883        applications. Or conversely if one wants wants a stronger
4884        default for QEMU than for all other applications, they can do
4885        this through this parameter. Its format is a gnutls priority
4886        string as described at
4887        https://gnutls.org/manual/html_node/Priority-Strings.html.
4889    ``-object tls-cipher-suites,id=id,priority=priority``
4890        Creates a TLS cipher suites object, which can be used to control
4891        the TLS cipher/protocol algorithms that applications are permitted
4892        to use.
4894        The ``id`` parameter is a unique ID which frontends will use to
4895        access the ordered list of permitted TLS cipher suites from the
4896        host.
4898        The ``priority`` parameter allows to override the global default
4899        priority used by gnutls. This can be useful if the system
4900        administrator needs to use a weaker set of crypto priorities for
4901        QEMU without potentially forcing the weakness onto all
4902        applications. Or conversely if one wants wants a stronger
4903        default for QEMU than for all other applications, they can do
4904        this through this parameter. Its format is a gnutls priority
4905        string as described at
4906        https://gnutls.org/manual/html_node/Priority-Strings.html.
4908        An example of use of this object is to control UEFI HTTPS Boot.
4909        The tls-cipher-suites object exposes the ordered list of permitted
4910        TLS cipher suites from the host side to the guest firmware, via
4911        fw_cfg. The list is represented as an array of IANA_TLS_CIPHER
4912        objects. The firmware uses the IANA_TLS_CIPHER array for configuring
4913        guest-side TLS.
4915        In the following example, the priority at which the host-side policy
4916        is retrieved is given by the ``priority`` property.
4917        Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to
4918        refer to /etc/crypto-policies/back-ends/gnutls.config.
4920        .. parsed-literal::
4922             # |qemu_system| \\
4923                 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\
4924                 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0
4926    ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
4927        Interval t can't be 0, this filter batches the packet delivery:
4928        all packets arriving in a given interval on netdev netdevid are
4929        delayed until the end of the interval. Interval is in
4930        microseconds. ``status`` is optional that indicate whether the
4931        netfilter is on (enabled) or off (disabled), the default status
4932        for netfilter will be 'on'.
4934        queue all\|rx\|tx is an option that can be applied to any
4935        netfilter.
4937        ``all``: the filter is attached both to the receive and the
4938        transmit queue of the netdev (default).
4940        ``rx``: the filter is attached to the receive queue of the
4941        netdev, where it will receive packets sent to the netdev.
4943        ``tx``: the filter is attached to the transmit queue of the
4944        netdev, where it will receive packets sent by the netdev.
4946        position head\|tail\|id=<id> is an option to specify where the
4947        filter should be inserted in the filter list. It can be applied
4948        to any netfilter.
4950        ``head``: the filter is inserted at the head of the filter list,
4951        before any existing filters.
4953        ``tail``: the filter is inserted at the tail of the filter list,
4954        behind any existing filters (default).
4956        ``id=<id>``: the filter is inserted before or behind the filter
4957        specified by <id>, see the insert option below.
4959        insert behind\|before is an option to specify where to insert
4960        the new filter relative to the one specified with
4961        position=id=<id>. It can be applied to any netfilter.
4963        ``before``: insert before the specified filter.
4965        ``behind``: insert behind the specified filter (default).
4967    ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4968        filter-mirror on netdev netdevid,mirror net packet to
4969        chardevchardevid, if it has the vnet\_hdr\_support flag,
4970        filter-mirror will mirror packet with vnet\_hdr\_len.
4972    ``-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]``
4973        filter-redirector on netdev netdevid,redirect filter's net
4974        packet to chardev chardevid,and redirect indev's packet to
4975        filter.if it has the vnet\_hdr\_support flag, filter-redirector
4976        will redirect packet with vnet\_hdr\_len. Create a
4977        filter-redirector we need to differ outdev id from indev id, id
4978        can not be the same. we can just use indev or outdev, but at
4979        least one of indev or outdev need to be specified.
4981    ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4982        Filter-rewriter is a part of COLO project.It will rewrite tcp
4983        packet to secondary from primary to keep secondary tcp
4984        connection,and rewrite tcp packet to primary from secondary make
4985        tcp packet can be handled by client.if it has the
4986        vnet\_hdr\_support flag, we can parse packet with vnet header.
4988        usage: colo secondary: -object
4989        filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object
4990        filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object
4991        filter-rewriter,id=rew0,netdev=hn0,queue=all
4993    ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]``
4994        Dump the network traffic on netdev dev to the file specified by
4995        filename. At most len bytes (64k by default) per packet are
4996        stored. The file format is libpcap, so it can be analyzed with
4997        tools such as tcpdump or Wireshark.
4999    ``-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}]``
5000        Colo-compare gets packet from primary\_in chardevid and
5001        secondary\_in, then compare whether the payload of primary packet
5002        and secondary packet are the same. If same, it will output
5003        primary packet to out\_dev, else it will notify COLO-framework to do
5004        checkpoint and send primary packet to out\_dev. In order to
5005        improve efficiency, we need to put the task of comparison in
5006        another iothread. If it has the vnet\_hdr\_support flag,
5007        colo compare will send/recv packet with vnet\_hdr\_len.
5008        The compare\_timeout=@var{ms} determines the maximum time of the
5009        colo-compare hold the packet. The expired\_scan\_cycle=@var{ms}
5010        is to set the period of scanning expired primary node network packets.
5011        The max\_queue\_size=@var{size} is to set the max compare queue
5012        size depend on user environment.
5013        If user want to use Xen COLO, need to add the notify\_dev to
5014        notify Xen colo-frame to do checkpoint.
5016        COLO-compare must be used with the help of filter-mirror,
5017        filter-redirector and filter-rewriter.
5019        ::
5021            KVM COLO
5023            primary:
5024            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
5025            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
5026            -chardev socket,id=mirror0,host=,port=9003,server=on,wait=off
5027            -chardev socket,id=compare1,host=,port=9004,server=on,wait=off
5028            -chardev socket,id=compare0,host=,port=9001,server=on,wait=off
5029            -chardev socket,id=compare0-0,host=,port=9001
5030            -chardev socket,id=compare_out,host=,port=9005,server=on,wait=off
5031            -chardev socket,id=compare_out0,host=,port=9005
5032            -object iothread,id=iothread1
5033            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
5034            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
5035            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
5036            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
5038            secondary:
5039            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
5040            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5041            -chardev socket,id=red0,host=,port=9003
5042            -chardev socket,id=red1,host=,port=9004
5043            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5044            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5047            Xen COLO
5049            primary:
5050            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
5051            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
5052            -chardev socket,id=mirror0,host=,port=9003,server=on,wait=off
5053            -chardev socket,id=compare1,host=,port=9004,server=on,wait=off
5054            -chardev socket,id=compare0,host=,port=9001,server=on,wait=off
5055            -chardev socket,id=compare0-0,host=,port=9001
5056            -chardev socket,id=compare_out,host=,port=9005,server=on,wait=off
5057            -chardev socket,id=compare_out0,host=,port=9005
5058            -chardev socket,id=notify_way,host=,port=9009,server=on,wait=off
5059            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
5060            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
5061            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
5062            -object iothread,id=iothread1
5063            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1
5065            secondary:
5066            -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
5067            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5068            -chardev socket,id=red0,host=,port=9003
5069            -chardev socket,id=red1,host=,port=9004
5070            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5071            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5073        If you want to know the detail of above command line, you can
5074        read the colo-compare git log.
5076    ``-object cryptodev-backend-builtin,id=id[,queues=queues]``
5077        Creates a cryptodev backend which executes crypto opreation from
5078        the QEMU cipher APIS. The id parameter is a unique ID that will
5079        be used to reference this cryptodev backend from the
5080        ``virtio-crypto`` device. The queues parameter is optional,
5081        which specify the queue number of cryptodev backend, the default
5082        of queues is 1.
5084        .. parsed-literal::
5086             # |qemu_system| \\
5087               [...] \\
5088                   -object cryptodev-backend-builtin,id=cryptodev0 \\
5089                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5090               [...]
5092    ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]``
5093        Creates a vhost-user cryptodev backend, backed by a chardev
5094        chardevid. The id parameter is a unique ID that will be used to
5095        reference this cryptodev backend from the ``virtio-crypto``
5096        device. The chardev should be a unix domain socket backed one.
5097        The vhost-user uses a specifically defined protocol to pass
5098        vhost ioctl replacement messages to an application on the other
5099        end of the socket. The queues parameter is optional, which
5100        specify the queue number of cryptodev backend for multiqueue
5101        vhost-user, the default of queues is 1.
5103        .. parsed-literal::
5105             # |qemu_system| \\
5106               [...] \\
5107                   -chardev socket,id=chardev0,path=/path/to/socket \\
5108                   -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\
5109                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5110               [...]
5112    ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]``
5113      \ 
5114    ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]``
5115        Defines a secret to store a password, encryption key, or some
5116        other sensitive data. The sensitive data can either be passed
5117        directly via the data parameter, or indirectly via the file
5118        parameter. Using the data parameter is insecure unless the
5119        sensitive data is encrypted.
5121        The sensitive data can be provided in raw format (the default),
5122        or base64. When encoded as JSON, the raw format only supports
5123        valid UTF-8 characters, so base64 is recommended for sending
5124        binary data. QEMU will convert from which ever format is
5125        provided to the format it needs internally. eg, an RBD password
5126        can be provided in raw format, even though it will be base64
5127        encoded when passed onto the RBD sever.
5129        For added protection, it is possible to encrypt the data
5130        associated with a secret using the AES-256-CBC cipher. Use of
5131        encryption is indicated by providing the keyid and iv
5132        parameters. The keyid parameter provides the ID of a previously
5133        defined secret that contains the AES-256 decryption key. This
5134        key should be 32-bytes long and be base64 encoded. The iv
5135        parameter provides the random initialization vector used for
5136        encryption of this particular secret and should be a base64
5137        encrypted string of the 16-byte IV.
5139        The simplest (insecure) usage is to provide the secret inline
5141        .. parsed-literal::
5143             # |qemu_system| -object secret,id=sec0,data=letmein,format=raw
5145        The simplest secure usage is to provide the secret via a file
5147        # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object
5148        secret,id=sec0,file=mypasswd.txt,format=raw
5150        For greater security, AES-256-CBC should be used. To illustrate
5151        usage, consider the openssl command line tool which can encrypt
5152        the data. Note that when encrypting, the plaintext must be
5153        padded to the cipher block size (32 bytes) using the standard
5154        PKCS#5/6 compatible padding algorithm.
5156        First a master key needs to be created in base64 encoding:
5158        ::
5160             # openssl rand -base64 32 > key.b64
5161             # KEY=$(base64 -d key.b64 | hexdump  -v -e '/1 "%02X"')
5163        Each secret to be encrypted needs to have a random
5164        initialization vector generated. These do not need to be kept
5165        secret
5167        ::
5169             # openssl rand -base64 16 > iv.b64
5170             # IV=$(base64 -d iv.b64 | hexdump  -v -e '/1 "%02X"')
5172        The secret to be defined can now be encrypted, in this case
5173        we're telling openssl to base64 encode the result, but it could
5174        be left as raw bytes if desired.
5176        ::
5178             # SECRET=$(printf "letmein" |
5179                        openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
5181        When launching QEMU, create a master secret pointing to
5182        ``key.b64`` and specify that to be used to decrypt the user
5183        password. Pass the contents of ``iv.b64`` to the second secret
5185        .. parsed-literal::
5187             # |qemu_system| \\
5188                 -object secret,id=secmaster0,format=base64,file=key.b64 \\
5189                 -object secret,id=sec0,keyid=secmaster0,format=base64,\\
5190                     data=$SECRET,iv=$(<iv.b64)
5192    ``-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,kernel-hashes=on|off]``
5193        Create a Secure Encrypted Virtualization (SEV) guest object,
5194        which can be used to provide the guest memory encryption support
5195        on AMD processors.
5197        When memory encryption is enabled, one of the physical address
5198        bit (aka the C-bit) is utilized to mark if a memory page is
5199        protected. The ``cbitpos`` is used to provide the C-bit
5200        position. The C-bit position is Host family dependent hence user
5201        must provide this value. On EPYC, the value should be 47.
5203        When memory encryption is enabled, we loose certain bits in
5204        physical address space. The ``reduced-phys-bits`` is used to
5205        provide the number of bits we loose in physical address space.
5206        Similar to C-bit, the value is Host family dependent. On EPYC,
5207        the value should be 5.
5209        The ``sev-device`` provides the device file to use for
5210        communicating with the SEV firmware running inside AMD Secure
5211        Processor. The default device is '/dev/sev'. If hardware
5212        supports memory encryption then /dev/sev devices are created by
5213        CCP driver.
5215        The ``policy`` provides the guest policy to be enforced by the
5216        SEV firmware and restrict what configuration and operational
5217        commands can be performed on this guest by the hypervisor. The
5218        policy should be provided by the guest owner and is bound to the
5219        guest and cannot be changed throughout the lifetime of the
5220        guest. The default is 0.
5222        If guest ``policy`` allows sharing the key with another SEV
5223        guest then ``handle`` can be use to provide handle of the guest
5224        from which to share the key.
5226        The ``dh-cert-file`` and ``session-file`` provides the guest
5227        owner's Public Diffie-Hillman key defined in SEV spec. The PDH
5228        and session parameters are used for establishing a cryptographic
5229        session with the guest owner to negotiate keys used for
5230        attestation. The file must be encoded in base64.
5232        The ``kernel-hashes`` adds the hashes of given kernel/initrd/
5233        cmdline to a designated guest firmware page for measured Linux
5234        boot with -kernel. The default is off. (Since 6.2)
5236        e.g to launch a SEV guest
5238        .. parsed-literal::
5240             # |qemu_system_x86| \\
5241                 ...... \\
5242                 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\
5243                 -machine ...,memory-encryption=sev0 \\
5244                 .....
5246    ``-object authz-simple,id=id,identity=string``
5247        Create an authorization object that will control access to
5248        network services.
5250        The ``identity`` parameter is identifies the user and its format
5251        depends on the network service that authorization object is
5252        associated with. For authorizing based on TLS x509 certificates,
5253        the identity must be the x509 distinguished name. Note that care
5254        must be taken to escape any commas in the distinguished name.
5256        An example authorization object to validate a x509 distinguished
5257        name would look like:
5259        .. parsed-literal::
5261             # |qemu_system| \\
5262                 ... \\
5263                 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\
5264                 ...
5266        Note the use of quotes due to the x509 distinguished name
5267        containing whitespace, and escaping of ','.
5269    ``-object authz-listfile,id=id,filename=path,refresh=on|off``
5270        Create an authorization object that will control access to
5271        network services.
5273        The ``filename`` parameter is the fully qualified path to a file
5274        containing the access control list rules in JSON format.
5276        An example set of rules that match against SASL usernames might
5277        look like:
5279        ::
5281              {
5282                "rules": [
5283                   { "match": "fred", "policy": "allow", "format": "exact" },
5284                   { "match": "bob", "policy": "allow", "format": "exact" },
5285                   { "match": "danb", "policy": "deny", "format": "glob" },
5286                   { "match": "dan*", "policy": "allow", "format": "exact" },
5287                ],
5288                "policy": "deny"
5289              }
5291        When checking access the object will iterate over all the rules
5292        and the first rule to match will have its ``policy`` value
5293        returned as the result. If no rules match, then the default
5294        ``policy`` value is returned.
5296        The rules can either be an exact string match, or they can use
5297        the simple UNIX glob pattern matching to allow wildcards to be
5298        used.
5300        If ``refresh`` is set to true the file will be monitored and
5301        automatically reloaded whenever its content changes.
5303        As with the ``authz-simple`` object, the format of the identity
5304        strings being matched depends on the network service, but is
5305        usually a TLS x509 distinguished name, or a SASL username.
5307        An example authorization object to validate a SASL username
5308        would look like:
5310        .. parsed-literal::
5312             # |qemu_system| \\
5313                 ... \\
5314                 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\
5315                 ...
5317    ``-object authz-pam,id=id,service=string``
5318        Create an authorization object that will control access to
5319        network services.
5321        The ``service`` parameter provides the name of a PAM service to
5322        use for authorization. It requires that a file
5323        ``/etc/pam.d/service`` exist to provide the configuration for
5324        the ``account`` subsystem.
5326        An example authorization object to validate a TLS x509
5327        distinguished name would look like:
5329        .. parsed-literal::
5331             # |qemu_system| \\
5332                 ... \\
5333                 -object authz-pam,id=auth0,service=qemu-vnc \\
5334                 ...
5336        There would then be a corresponding config file for PAM at
5337        ``/etc/pam.d/qemu-vnc`` that contains:
5339        ::
5341            account requisite  pam_listfile.so item=user sense=allow \
5342                       file=/etc/qemu/vnc.allow
5344        Finally the ``/etc/qemu/vnc.allow`` file would contain the list
5345        of x509 distingished names that are permitted access
5347        ::
5349            CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
5351    ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch``
5352        Creates a dedicated event loop thread that devices can be
5353        assigned to. This is known as an IOThread. By default device
5354        emulation happens in vCPU threads or the main event loop thread.
5355        This can become a scalability bottleneck. IOThreads allow device
5356        emulation and I/O to run on other host CPUs.
5358        The ``id`` parameter is a unique ID that will be used to
5359        reference this IOThread from ``-device ...,iothread=id``.
5360        Multiple devices can be assigned to an IOThread. Note that not
5361        all devices support an ``iothread`` parameter.
5363        The ``query-iothreads`` QMP command lists IOThreads and reports
5364        their thread IDs so that the user can configure host CPU
5365        pinning/affinity.
5367        IOThreads use an adaptive polling algorithm to reduce event loop
5368        latency. Instead of entering a blocking system call to monitor
5369        file descriptors and then pay the cost of being woken up when an
5370        event occurs, the polling algorithm spins waiting for events for
5371        a short time. The algorithm's default parameters are suitable
5372        for many cases but can be adjusted based on knowledge of the
5373        workload and/or host device latency.
5375        The ``poll-max-ns`` parameter is the maximum number of
5376        nanoseconds to busy wait for events. Polling can be disabled by
5377        setting this value to 0.
5379        The ``poll-grow`` parameter is the multiplier used to increase
5380        the polling time when the algorithm detects it is missing events
5381        due to not polling long enough.
5383        The ``poll-shrink`` parameter is the divisor used to decrease
5384        the polling time when the algorithm detects it is spending too
5385        long polling without encountering events.
5387        The ``aio-max-batch`` parameter is the maximum number of requests
5388        in a batch for the AIO engine, 0 means that the engine will use
5389        its default.
5391        The IOThread parameters can be modified at run-time using the
5392        ``qom-set`` command (where ``iothread1`` is the IOThread's
5393        ``id``):
5395        ::
5397            (qemu) qom-set /objects/iothread1 poll-max-ns 100000
5401HXCOMM This is the last statement. Insert new options before this line!
5403#undef DEF
5404#undef DEFHEADING
5405#undef ARCHHEADING