xref: /openbmc/qemu/qemu-options.hx (revision 05caa062)
1HXCOMM See docs/devel/docs.rst for the format of this file.
2HXCOMM
3HXCOMM Use DEFHEADING() to define headings in both help text and rST.
4HXCOMM Text between SRST and ERST is copied to the rST version and
5HXCOMM discarded from C version.
6HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to
7HXCOMM construct option structures, enums and help message for specified
8HXCOMM architectures.
9HXCOMM HXCOMM can be used for comments, discarded from both rST and C.
10
11DEFHEADING(Standard options:)
12
13DEF("help", 0, QEMU_OPTION_h,
14    "-h or -help     display this help and exit\n", QEMU_ARCH_ALL)
15SRST
16``-h``
17    Display help and exit
18ERST
19
20DEF("version", 0, QEMU_OPTION_version,
21    "-version        display version information and exit\n", QEMU_ARCH_ALL)
22SRST
23``-version``
24    Display version information and exit
25ERST
26
27DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
28    "-machine [type=]name[,prop[=value][,...]]\n"
29    "                selects emulated machine ('-machine help' for list)\n"
30    "                property accel=accel1[:accel2[:...]] selects accelerator\n"
31    "                supported accelerators are kvm, xen, hvf, nvmm, whpx or tcg (default: tcg)\n"
32    "                vmport=on|off|auto controls emulation of vmport (default: auto)\n"
33    "                dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
34    "                mem-merge=on|off controls memory merge support (default: on)\n"
35    "                aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
36    "                dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
37    "                suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
38    "                nvdimm=on|off controls NVDIMM support (default=off)\n"
39    "                memory-encryption=@var{} memory encryption object to use (default=none)\n"
40    "                hmat=on|off controls ACPI HMAT support (default=off)\n"
41    "                memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n"
42    "                cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n",
43    QEMU_ARCH_ALL)
44SRST
45``-machine [type=]name[,prop=value[,...]]``
46    Select the emulated machine by name. Use ``-machine help`` to list
47    available machines.
48
49    For architectures which aim to support live migration compatibility
50    across releases, each release will introduce a new versioned machine
51    type. For example, the 2.8.0 release introduced machine types
52    "pc-i440fx-2.8" and "pc-q35-2.8" for the x86\_64/i686 architectures.
53
54    To allow live migration of guests from QEMU version 2.8.0, to QEMU
55    version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8"
56    and "pc-q35-2.8" machines too. To allow users live migrating VMs to
57    skip multiple intermediate releases when upgrading, new releases of
58    QEMU will support machine types from many previous versions.
59
60    Supported machine properties are:
61
62    ``accel=accels1[:accels2[:...]]``
63        This is used to enable an accelerator. Depending on the target
64        architecture, kvm, xen, hvf, nvmm, whpx or tcg can be available.
65        By default, tcg is used. If there is more than one accelerator
66        specified, the next one is used if the previous one fails to
67        initialize.
68
69    ``vmport=on|off|auto``
70        Enables emulation of VMWare IO port, for vmmouse etc. auto says
71        to select the value based on accel and i8042. For accel=xen or
72        i8042=off the default is off otherwise the default is on.
73
74    ``dump-guest-core=on|off``
75        Include guest memory in a core dump. The default is on.
76
77    ``mem-merge=on|off``
78        Enables or disables memory merge support. This feature, when
79        supported by the host, de-duplicates identical memory pages
80        among VMs instances (enabled by default).
81
82    ``aes-key-wrap=on|off``
83        Enables or disables AES key wrapping support on s390-ccw hosts.
84        This feature controls whether AES wrapping keys will be created
85        to allow execution of AES cryptographic functions. The default
86        is on.
87
88    ``dea-key-wrap=on|off``
89        Enables or disables DEA key wrapping support on s390-ccw hosts.
90        This feature controls whether DEA wrapping keys will be created
91        to allow execution of DEA cryptographic functions. The default
92        is on.
93
94    ``nvdimm=on|off``
95        Enables or disables NVDIMM support. The default is off.
96
97    ``memory-encryption=``
98        Memory encryption object to use. The default is none.
99
100    ``hmat=on|off``
101        Enables or disables ACPI Heterogeneous Memory Attribute Table
102        (HMAT) support. The default is off.
103
104    ``memory-backend='id'``
105        An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options.
106        Allows to use a memory backend as main RAM.
107
108        For example:
109        ::
110
111            -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on
112            -machine memory-backend=pc.ram
113            -m 512M
114
115        Migration compatibility note:
116
117        * as backend id one shall use value of 'default-ram-id', advertised by
118          machine type (available via ``query-machines`` QMP command), if migration
119          to/from old QEMU (<5.0) is expected.
120        * for machine types 4.0 and older, user shall
121          use ``x-use-canonical-path-for-ramblock-id=off`` backend option
122          if migration to/from old QEMU (<5.0) is expected.
123
124        For example:
125        ::
126
127            -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off
128            -machine memory-backend=pc.ram
129            -m 512M
130
131    ``cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]``
132        Define a CXL Fixed Memory Window (CFMW).
133
134        Described in the CXL 2.0 ECN: CEDT CFMWS & QTG _DSM.
135
136        They are regions of Host Physical Addresses (HPA) on a system which
137        may be interleaved across one or more CXL host bridges.  The system
138        software will assign particular devices into these windows and
139        configure the downstream Host-managed Device Memory (HDM) decoders
140        in root ports, switch ports and devices appropriately to meet the
141        interleave requirements before enabling the memory devices.
142
143        ``targets.X=target`` provides the mapping to CXL host bridges
144        which may be identified by the id provided in the -device entry.
145        Multiple entries are needed to specify all the targets when
146        the fixed memory window represents interleaved memory. X is the
147        target index from 0.
148
149        ``size=size`` sets the size of the CFMW. This must be a multiple of
150        256MiB. The region will be aligned to 256MiB but the location is
151        platform and configuration dependent.
152
153        ``interleave-granularity=granularity`` sets the granularity of
154        interleave. Default 256 (bytes). Only 256, 512, 1k, 2k,
155        4k, 8k and 16k granularities supported.
156
157        Example:
158
159        ::
160
161            -machine cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.targets.1=cxl.1,cxl-fmw.0.size=128G,cxl-fmw.0.interleave-granularity=512
162ERST
163
164DEF("M", HAS_ARG, QEMU_OPTION_M,
165    "                sgx-epc.0.memdev=memid,sgx-epc.0.node=numaid\n",
166    QEMU_ARCH_ALL)
167
168SRST
169``sgx-epc.0.memdev=@var{memid},sgx-epc.0.node=@var{numaid}``
170    Define an SGX EPC section.
171ERST
172
173DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
174    "-cpu cpu        select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
175SRST
176``-cpu model``
177    Select CPU model (``-cpu help`` for list and additional feature
178    selection)
179ERST
180
181DEF("accel", HAS_ARG, QEMU_OPTION_accel,
182    "-accel [accel=]accelerator[,prop[=value][,...]]\n"
183    "                select accelerator (kvm, xen, hvf, nvmm, whpx or tcg; use 'help' for a list)\n"
184    "                igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
185    "                kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
186    "                kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
187    "                one-insn-per-tb=on|off (one guest instruction per TCG translation block)\n"
188    "                split-wx=on|off (enable TCG split w^x mapping)\n"
189    "                tb-size=n (TCG translation block cache size)\n"
190    "                dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n"
191    "                eager-split-size=n (KVM Eager Page Split chunk size, default 0, disabled. ARM only)\n"
192    "                notify-vmexit=run|internal-error|disable,notify-window=n (enable notify VM exit and set notify window, x86 only)\n"
193    "                thread=single|multi (enable multi-threaded TCG)\n"
194    "                device=path (KVM device path, default /dev/kvm)\n", QEMU_ARCH_ALL)
195SRST
196``-accel name[,prop=value[,...]]``
197    This is used to enable an accelerator. Depending on the target
198    architecture, kvm, xen, hvf, nvmm, whpx or tcg can be available. By
199    default, tcg is used. If there is more than one accelerator
200    specified, the next one is used if the previous one fails to
201    initialize.
202
203    ``igd-passthru=on|off``
204        When Xen is in use, this option controls whether Intel
205        integrated graphics devices can be passed through to the guest
206        (default=off)
207
208    ``kernel-irqchip=on|off|split``
209        Controls KVM in-kernel irqchip support. The default is full
210        acceleration of the interrupt controllers. On x86, split irqchip
211        reduces the kernel attack surface, at a performance cost for
212        non-MSI interrupts. Disabling the in-kernel irqchip completely
213        is not recommended except for debugging purposes.
214
215    ``kvm-shadow-mem=size``
216        Defines the size of the KVM shadow MMU.
217
218    ``one-insn-per-tb=on|off``
219        Makes the TCG accelerator put only one guest instruction into
220        each translation block. This slows down emulation a lot, but
221        can be useful in some situations, such as when trying to analyse
222        the logs produced by the ``-d`` option.
223
224    ``split-wx=on|off``
225        Controls the use of split w^x mapping for the TCG code generation
226        buffer. Some operating systems require this to be enabled, and in
227        such a case this will default on. On other operating systems, this
228        will default off, but one may enable this for testing or debugging.
229
230    ``tb-size=n``
231        Controls the size (in MiB) of the TCG translation block cache.
232
233    ``thread=single|multi``
234        Controls number of TCG threads. When the TCG is multi-threaded
235        there will be one thread per vCPU therefore taking advantage of
236        additional host cores. The default is to enable multi-threading
237        where both the back-end and front-ends support it and no
238        incompatible TCG features have been enabled (e.g.
239        icount/replay).
240
241    ``dirty-ring-size=n``
242        When the KVM accelerator is used, it controls the size of the per-vCPU
243        dirty page ring buffer (number of entries for each vCPU). It should
244        be a value that is power of two, and it should be 1024 or bigger (but
245        still less than the maximum value that the kernel supports).  4096
246        could be a good initial value if you have no idea which is the best.
247        Set this value to 0 to disable the feature.  By default, this feature
248        is disabled (dirty-ring-size=0).  When enabled, KVM will instead
249        record dirty pages in a bitmap.
250
251    ``eager-split-size=n``
252        KVM implements dirty page logging at the PAGE_SIZE granularity and
253        enabling dirty-logging on a huge-page requires breaking it into
254        PAGE_SIZE pages in the first place. KVM on ARM does this splitting
255        lazily by default. There are performance benefits in doing huge-page
256        split eagerly, especially in situations where TLBI costs associated
257        with break-before-make sequences are considerable and also if guest
258        workloads are read intensive. The size here specifies how many pages
259        to break at a time and needs to be a valid block size which is
260        1GB/2MB/4KB, 32MB/16KB and 512MB/64KB for 4KB/16KB/64KB PAGE_SIZE
261        respectively. Be wary of specifying a higher size as it will have an
262        impact on the memory. By default, this feature is disabled
263        (eager-split-size=0).
264
265    ``notify-vmexit=run|internal-error|disable,notify-window=n``
266        Enables or disables notify VM exit support on x86 host and specify
267        the corresponding notify window to trigger the VM exit if enabled.
268        ``run`` option enables the feature. It does nothing and continue
269        if the exit happens. ``internal-error`` option enables the feature.
270        It raises a internal error. ``disable`` option doesn't enable the feature.
271        This feature can mitigate the CPU stuck issue due to event windows don't
272        open up for a specified of time (i.e. notify-window).
273        Default: notify-vmexit=run,notify-window=0.
274
275    ``device=path``
276        Sets the path to the KVM device node. Defaults to ``/dev/kvm``. This
277        option can be used to pass the KVM device to use via a file descriptor
278        by setting the value to ``/dev/fdset/NN``.
279
280ERST
281
282DEF("smp", HAS_ARG, QEMU_OPTION_smp,
283    "-smp [[cpus=]n][,maxcpus=maxcpus][,drawers=drawers][,books=books][,sockets=sockets]\n"
284    "               [,dies=dies][,clusters=clusters][,modules=modules][,cores=cores]\n"
285    "               [,threads=threads]\n"
286    "                set the number of initial CPUs to 'n' [default=1]\n"
287    "                maxcpus= maximum number of total CPUs, including\n"
288    "                offline CPUs for hotplug, etc\n"
289    "                drawers= number of drawers on the machine board\n"
290    "                books= number of books in one drawer\n"
291    "                sockets= number of sockets in one book\n"
292    "                dies= number of dies in one socket\n"
293    "                clusters= number of clusters in one die\n"
294    "                modules= number of modules in one cluster\n"
295    "                cores= number of cores in one module\n"
296    "                threads= number of threads in one core\n"
297    "Note: Different machines may have different subsets of the CPU topology\n"
298    "      parameters supported, so the actual meaning of the supported parameters\n"
299    "      will vary accordingly. For example, for a machine type that supports a\n"
300    "      three-level CPU hierarchy of sockets/cores/threads, the parameters will\n"
301    "      sequentially mean as below:\n"
302    "                sockets means the number of sockets on the machine board\n"
303    "                cores means the number of cores in one socket\n"
304    "                threads means the number of threads in one core\n"
305    "      For a particular machine type board, an expected CPU topology hierarchy\n"
306    "      can be defined through the supported sub-option. Unsupported parameters\n"
307    "      can also be provided in addition to the sub-option, but their values\n"
308    "      must be set as 1 in the purpose of correct parsing.\n",
309    QEMU_ARCH_ALL)
310SRST
311``-smp [[cpus=]n][,maxcpus=maxcpus][,drawers=drawers][,books=books][,sockets=sockets][,dies=dies][,clusters=clusters][,modules=modules][,cores=cores][,threads=threads]``
312    Simulate a SMP system with '\ ``n``\ ' CPUs initially present on
313    the machine type board. On boards supporting CPU hotplug, the optional
314    '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be
315    added at runtime. When both parameters are omitted, the maximum number
316    of CPUs will be calculated from the provided topology members and the
317    initial CPU count will match the maximum number. When only one of them
318    is given then the omitted one will be set to its counterpart's value.
319    Both parameters may be specified, but the maximum number of CPUs must
320    be equal to or greater than the initial CPU count. Product of the
321    CPU topology hierarchy must be equal to the maximum number of CPUs.
322    Both parameters are subject to an upper limit that is determined by
323    the specific machine type chosen.
324
325    To control reporting of CPU topology information, values of the topology
326    parameters can be specified. Machines may only support a subset of the
327    parameters and different machines may have different subsets supported
328    which vary depending on capacity of the corresponding CPU targets. So
329    for a particular machine type board, an expected topology hierarchy can
330    be defined through the supported sub-option. Unsupported parameters can
331    also be provided in addition to the sub-option, but their values must be
332    set as 1 in the purpose of correct parsing.
333
334    Either the initial CPU count, or at least one of the topology parameters
335    must be specified. The specified parameters must be greater than zero,
336    explicit configuration like "cpus=0" is not allowed. Values for any
337    omitted parameters will be computed from those which are given.
338
339    For example, the following sub-option defines a CPU topology hierarchy
340    (2 sockets totally on the machine, 2 cores per socket, 2 threads per
341    core) for a machine that only supports sockets/cores/threads.
342    Some members of the option can be omitted but their values will be
343    automatically computed:
344
345    ::
346
347        -smp 8,sockets=2,cores=2,threads=2,maxcpus=8
348
349    The following sub-option defines a CPU topology hierarchy (2 sockets
350    totally on the machine, 2 dies per socket, 2 modules per die, 2 cores per
351    module, 2 threads per core) for PC machines which support sockets/dies
352    /modules/cores/threads. Some members of the option can be omitted but
353    their values will be automatically computed:
354
355    ::
356
357        -smp 32,sockets=2,dies=2,modules=2,cores=2,threads=2,maxcpus=32
358
359    The following sub-option defines a CPU topology hierarchy (2 sockets
360    totally on the machine, 2 clusters per socket, 2 cores per cluster,
361    2 threads per core) for ARM virt machines which support sockets/clusters
362    /cores/threads. Some members of the option can be omitted but their values
363    will be automatically computed:
364
365    ::
366
367        -smp 16,sockets=2,clusters=2,cores=2,threads=2,maxcpus=16
368
369    Historically preference was given to the coarsest topology parameters
370    when computing missing values (ie sockets preferred over cores, which
371    were preferred over threads), however, this behaviour is considered
372    liable to change. Prior to 6.2 the preference was sockets over cores
373    over threads. Since 6.2 the preference is cores over sockets over threads.
374
375    For example, the following option defines a machine board with 2 sockets
376    of 1 core before 6.2 and 1 socket of 2 cores after 6.2:
377
378    ::
379
380        -smp 2
381
382    Note: The cluster topology will only be generated in ACPI and exposed
383    to guest if it's explicitly specified in -smp.
384ERST
385
386DEF("numa", HAS_ARG, QEMU_OPTION_numa,
387    "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
388    "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
389    "-numa dist,src=source,dst=destination,val=distance\n"
390    "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
391    "-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"
392    "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
393    QEMU_ARCH_ALL)
394SRST
395``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
396  \
397``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
398  \
399``-numa dist,src=source,dst=destination,val=distance``
400  \
401``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]``
402  \
403``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=type[,latency=lat][,bandwidth=bw]``
404  \
405``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]``
406    Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA
407    distance from a source node to a destination node. Set the ACPI
408    Heterogeneous Memory Attributes for the given nodes.
409
410    Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and
411    lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a
412    contiguous range of CPU indexes (or a single VCPU if lastcpu is
413    omitted). A non-contiguous set of VCPUs can be represented by
414    providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is
415    omitted on all nodes, VCPUs are automatically split between them.
416
417    For example, the following option assigns VCPUs 0, 1, 2 and 5 to a
418    NUMA node:
419
420    ::
421
422        -numa node,cpus=0-2,cpus=5
423
424    '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option
425    which uses '\ ``socket-id|core-id|thread-id``\ ' properties to
426    assign CPU objects to a node using topology layout properties of
427    CPU. The set of properties is machine specific, and depends on used
428    machine type/'\ ``smp``\ ' options. It could be queried with
429    '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ '
430    property specifies node to which CPU object will be assigned, it's
431    required for node to be declared with '\ ``node``\ ' option before
432    it's used with '\ ``cpu``\ ' option.
433
434    For example:
435
436    ::
437
438        -M pc \
439        -smp 1,sockets=2,maxcpus=2 \
440        -numa node,nodeid=0 -numa node,nodeid=1 \
441        -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
442
443    '\ ``memdev``\ ' option assigns RAM from a given memory backend
444    device to a node. It is recommended to use '\ ``memdev``\ ' option
445    over legacy '\ ``mem``\ ' option. This is because '\ ``memdev``\ '
446    option provides better performance and more control over the
447    backend's RAM (e.g. '\ ``prealloc``\ ' parameter of
448    '\ ``-memory-backend-ram``\ ' allows memory preallocation).
449
450    For compatibility reasons, legacy '\ ``mem``\ ' option is
451    supported in 5.0 and older machine types. Note that '\ ``mem``\ '
452    and '\ ``memdev``\ ' are mutually exclusive. If one node uses
453    '\ ``memdev``\ ', the rest nodes have to use '\ ``memdev``\ '
454    option, and vice versa.
455
456    Users must specify memory for all NUMA nodes by '\ ``memdev``\ '
457    (or legacy '\ ``mem``\ ' if available). In QEMU 5.2, the support
458    for '\ ``-numa node``\ ' without memory specified was removed.
459
460    '\ ``initiator``\ ' is an additional option that points to an
461    initiator NUMA node that has best performance (the lowest latency or
462    largest bandwidth) to this NUMA node. Note that this option can be
463    set only when the machine property 'hmat' is set to 'on'.
464
465    Following example creates a machine with 2 NUMA nodes, node 0 has
466    CPU. node 1 has only memory, and its initiator is node 0. Note that
467    because node 0 has CPU, by default the initiator of node 0 is itself
468    and must be itself.
469
470    ::
471
472        -machine hmat=on \
473        -m 2G,slots=2,maxmem=4G \
474        -object memory-backend-ram,size=1G,id=m0 \
475        -object memory-backend-ram,size=1G,id=m1 \
476        -numa node,nodeid=0,memdev=m0 \
477        -numa node,nodeid=1,memdev=m1,initiator=0 \
478        -smp 2,sockets=2,maxcpus=2  \
479        -numa cpu,node-id=0,socket-id=0 \
480        -numa cpu,node-id=0,socket-id=1
481
482    source and destination are NUMA node IDs. distance is the NUMA
483    distance from source to destination. The distance from a node to
484    itself is always 10. If any pair of nodes is given a distance, then
485    all pairs must be given distances. Although, when distances are only
486    given in one direction for each pair of nodes, then the distances in
487    the opposite directions are assumed to be the same. If, however, an
488    asymmetrical pair of distances is given for even one node pair, then
489    all node pairs must be provided distance values for both directions,
490    even when they are symmetrical. When a node is unreachable from
491    another node, set the pair's distance to 255.
492
493    Note that the -``numa`` option doesn't allocate any of the specified
494    resources, it just assigns existing resources to NUMA nodes. This
495    means that one still has to use the ``-m``, ``-smp`` options to
496    allocate RAM and VCPUs respectively.
497
498    Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
499    Information between initiator and target NUMA nodes in ACPI
500    Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can
501    create memory requests, usually it has one or more processors.
502    Target NUMA node contains addressable memory.
503
504    In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is
505    the memory hierarchy of the target NUMA node: if hierarchy is
506    'memory', the structure represents the memory performance; if
507    hierarchy is 'first-level\|second-level\|third-level', this
508    structure represents aggregated performance of memory side caches
509    for each domain. type of 'data-type' is type of data represented by
510    this structure instance: if 'hierarchy' is 'memory', 'data-type' is
511    'access\|read\|write' latency or 'access\|read\|write' bandwidth of
512    the target memory; if 'hierarchy' is
513    'first-level\|second-level\|third-level', 'data-type' is
514    'access\|read\|write' hit latency or 'access\|read\|write' hit
515    bandwidth of the target memory side cache.
516
517    lat is latency value in nanoseconds. bw is bandwidth value, the
518    possible value and units are NUM[M\|G\|T], mean that the bandwidth
519    value are NUM byte per second (or MB/s, GB/s or TB/s depending on
520    used suffix). Note that if latency or bandwidth value is 0, means
521    the corresponding latency or bandwidth information is not provided.
522
523    In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory
524    belongs. size is the size of memory side cache in bytes. level is
525    the cache level described in this structure, note that the cache
526    level 0 should not be used with '\ ``hmat-cache``\ ' option.
527    associativity is the cache associativity, the possible value is
528    'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
529    is the write policy. line is the cache Line size in bytes.
530
531    For example, the following options describe 2 NUMA nodes. Node 0 has
532    2 cpus and a ram, node 1 has only a ram. The processors in node 0
533    access memory in node 0 with access-latency 5 nanoseconds,
534    access-bandwidth is 200 MB/s; The processors in NUMA node 0 access
535    memory in NUMA node 1 with access-latency 10 nanoseconds,
536    access-bandwidth is 100 MB/s. And for memory side cache information,
537    NUMA node 0 and 1 both have 1 level memory cache, size is 10KB,
538    policy is write-back, the cache Line size is 8 bytes:
539
540    ::
541
542        -machine hmat=on \
543        -m 2G \
544        -object memory-backend-ram,size=1G,id=m0 \
545        -object memory-backend-ram,size=1G,id=m1 \
546        -smp 2,sockets=2,maxcpus=2 \
547        -numa node,nodeid=0,memdev=m0 \
548        -numa node,nodeid=1,memdev=m1,initiator=0 \
549        -numa cpu,node-id=0,socket-id=0 \
550        -numa cpu,node-id=0,socket-id=1 \
551        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
552        -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
553        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
554        -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
555        -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
556        -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
557ERST
558
559DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
560    "-add-fd fd=fd,set=set[,opaque=opaque]\n"
561    "                Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
562SRST
563``-add-fd fd=fd,set=set[,opaque=opaque]``
564    Add a file descriptor to an fd set. Valid options are:
565
566    ``fd=fd``
567        This option defines the file descriptor of which a duplicate is
568        added to fd set. The file descriptor cannot be stdin, stdout, or
569        stderr.
570
571    ``set=set``
572        This option defines the ID of the fd set to add the file
573        descriptor to.
574
575    ``opaque=opaque``
576        This option defines a free-form string that can be used to
577        describe fd.
578
579    You can open an image using pre-opened file descriptors from an fd
580    set:
581
582    .. parsed-literal::
583
584        |qemu_system| \\
585         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
586         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
587         -drive file=/dev/fdset/2,index=0,media=disk
588ERST
589
590DEF("set", HAS_ARG, QEMU_OPTION_set,
591    "-set group.id.arg=value\n"
592    "                set <arg> parameter for item <id> of type <group>\n"
593    "                i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
594SRST
595``-set group.id.arg=value``
596    Set parameter arg for item id of type group
597ERST
598
599DEF("global", HAS_ARG, QEMU_OPTION_global,
600    "-global driver.property=value\n"
601    "-global driver=driver,property=property,value=value\n"
602    "                set a global default for a driver property\n",
603    QEMU_ARCH_ALL)
604SRST
605``-global driver.prop=value``
606  \
607``-global driver=driver,property=property,value=value``
608    Set default value of driver's property prop to value, e.g.:
609
610    .. parsed-literal::
611
612        |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img
613
614    In particular, you can use this to set driver properties for devices
615    which are created automatically by the machine model. To create a
616    device which is not created automatically and set properties on it,
617    use -``device``.
618
619    -global driver.prop=value is shorthand for -global
620    driver=driver,property=prop,value=value. The longhand syntax works
621    even when driver contains a dot.
622ERST
623
624DEF("boot", HAS_ARG, QEMU_OPTION_boot,
625    "-boot [order=drives][,once=drives][,menu=on|off]\n"
626    "      [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
627    "                'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
628    "                'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
629    "                'sp_time': the period that splash picture last if menu=on, unit is ms\n"
630    "                'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
631    QEMU_ARCH_ALL)
632SRST
633``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
634    Specify boot order drives as a string of drive letters. Valid drive
635    letters depend on the target architecture. The x86 PC uses: a, b
636    (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
637    (Etherboot from network adapter 1-4), hard disk boot is the default.
638    To apply a particular boot order only on the first startup, specify
639    it via ``once``. Note that the ``order`` or ``once`` parameter
640    should not be used together with the ``bootindex`` property of
641    devices, since the firmware implementations normally do not support
642    both at the same time.
643
644    Interactive boot menus/prompts can be enabled via ``menu=on`` as far
645    as firmware/BIOS supports them. The default is non-interactive boot.
646
647    A splash picture could be passed to bios, enabling user to show it
648    as logo, when option splash=sp\_name is given and menu=on, If
649    firmware/BIOS supports them. Currently Seabios for X86 system
650    support it. limitation: The splash file could be a jpeg file or a
651    BMP file in 24 BPP format(true color). The resolution should be
652    supported by the SVGA mode, so the recommended is 320x240, 640x480,
653    800x640.
654
655    A timeout could be passed to bios, guest will pause for rb\_timeout
656    ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
657    not reboot, qemu passes '-1' to bios by default. Currently Seabios
658    for X86 system support it.
659
660    Do strict boot via ``strict=on`` as far as firmware/BIOS supports
661    it. This only effects when boot priority is changed by bootindex
662    options. The default is non-strict boot.
663
664    .. parsed-literal::
665
666        # try to boot from network first, then from hard disk
667        |qemu_system_x86| -boot order=nc
668        # boot from CD-ROM first, switch back to default order after reboot
669        |qemu_system_x86| -boot once=d
670        # boot with a splash picture for 5 seconds.
671        |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000
672
673    Note: The legacy format '-boot drives' is still supported but its
674    use is discouraged as it may be removed from future versions.
675ERST
676
677DEF("m", HAS_ARG, QEMU_OPTION_m,
678    "-m [size=]megs[,slots=n,maxmem=size]\n"
679    "                configure guest RAM\n"
680    "                size: initial amount of guest memory\n"
681    "                slots: number of hotplug slots (default: none)\n"
682    "                maxmem: maximum amount of guest memory (default: none)\n"
683    "                Note: Some architectures might enforce a specific granularity\n",
684    QEMU_ARCH_ALL)
685SRST
686``-m [size=]megs[,slots=n,maxmem=size]``
687    Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
688    Optionally, a suffix of "M" or "G" can be used to signify a value in
689    megabytes or gigabytes respectively. Optional pair slots, maxmem
690    could be used to set amount of hotpluggable memory slots and maximum
691    amount of memory. Note that maxmem must be aligned to the page size.
692
693    For example, the following command-line sets the guest startup RAM
694    size to 1GB, creates 3 slots to hotplug additional memory and sets
695    the maximum memory the guest can reach to 4GB:
696
697    .. parsed-literal::
698
699        |qemu_system| -m 1G,slots=3,maxmem=4G
700
701    If slots and maxmem are not specified, memory hotplug won't be
702    enabled and the guest startup RAM will never increase.
703ERST
704
705DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
706    "-mem-path FILE  provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
707SRST
708``-mem-path path``
709    Allocate guest RAM from a temporarily created file in path.
710ERST
711
712DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
713    "-mem-prealloc   preallocate guest memory (use with -mem-path)\n",
714    QEMU_ARCH_ALL)
715SRST
716``-mem-prealloc``
717    Preallocate memory when using -mem-path.
718ERST
719
720DEF("k", HAS_ARG, QEMU_OPTION_k,
721    "-k language     use keyboard layout (for example 'fr' for French)\n",
722    QEMU_ARCH_ALL)
723SRST
724``-k language``
725    Use keyboard layout language (for example ``fr`` for French). This
726    option is only needed where it is not easy to get raw PC keycodes
727    (e.g. on Macs, with some X11 servers or with a VNC or curses
728    display). You don't normally need to use it on PC/Linux or
729    PC/Windows hosts.
730
731    The available layouts are:
732
733    ::
734
735        ar  de-ch  es  fo     fr-ca  hu  ja  mk     no  pt-br  sv
736        da  en-gb  et  fr     fr-ch  is  lt  nl     pl  ru     th
737        de  en-us  fi  fr-be  hr     it  lv  nl-be  pt  sl     tr
738
739    The default is ``en-us``.
740ERST
741
742
743DEF("audio", HAS_ARG, QEMU_OPTION_audio,
744    "-audio [driver=]driver[,prop[=value][,...]]\n"
745    "                specifies default audio backend when `audiodev` is not\n"
746    "                used to create a machine or sound device;"
747    "                options are the same as for -audiodev\n"
748    "-audio [driver=]driver,model=value[,prop[=value][,...]]\n"
749    "                specifies the audio backend and device to use;\n"
750    "                apart from 'model', options are the same as for -audiodev.\n"
751    "                use '-audio model=help' to show possible devices.\n",
752    QEMU_ARCH_ALL)
753SRST
754``-audio [driver=]driver[,model=value][,prop[=value][,...]]``
755    If the ``model`` option is specified, ``-audio`` is a shortcut
756    for configuring both the guest audio hardware and the host audio
757    backend in one go. The guest hardware model can be set with
758    ``model=modelname``.  Use ``model=help`` to list the available
759    device types.
760
761    The following two example do exactly the same, to show how ``-audio``
762    can be used to shorten the command line length:
763
764    .. parsed-literal::
765
766        |qemu_system| -audiodev pa,id=pa -device sb16,audiodev=pa
767        |qemu_system| -audio pa,model=sb16
768
769    If the ``model`` option is not specified, ``-audio`` is used to
770    configure a default audio backend that will be used whenever the
771    ``audiodev`` property is not set on a device or machine.  In
772    particular, ``-audio none`` ensures that no audio is produced even
773    for machines that have embedded sound hardware.
774
775    In both cases, the driver option is the same as with the corresponding
776    ``-audiodev`` option below.  Use ``driver=help`` to list the available
777    drivers.
778
779ERST
780
781DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
782    "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
783    "                specifies the audio backend to use\n"
784    "                Use ``-audiodev help`` to list the available drivers\n"
785    "                id= identifier of the backend\n"
786    "                timer-period= timer period in microseconds\n"
787    "                in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
788    "                in|out.fixed-settings= use fixed settings for host audio\n"
789    "                in|out.frequency= frequency to use with fixed settings\n"
790    "                in|out.channels= number of channels to use with fixed settings\n"
791    "                in|out.format= sample format to use with fixed settings\n"
792    "                valid values: s8, s16, s32, u8, u16, u32, f32\n"
793    "                in|out.voices= number of voices to use\n"
794    "                in|out.buffer-length= length of buffer in microseconds\n"
795    "-audiodev none,id=id,[,prop[=value][,...]]\n"
796    "                dummy driver that discards all output\n"
797#ifdef CONFIG_AUDIO_ALSA
798    "-audiodev alsa,id=id[,prop[=value][,...]]\n"
799    "                in|out.dev= name of the audio device to use\n"
800    "                in|out.period-length= length of period in microseconds\n"
801    "                in|out.try-poll= attempt to use poll mode\n"
802    "                threshold= threshold (in microseconds) when playback starts\n"
803#endif
804#ifdef CONFIG_AUDIO_COREAUDIO
805    "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
806    "                in|out.buffer-count= number of buffers\n"
807#endif
808#ifdef CONFIG_AUDIO_DSOUND
809    "-audiodev dsound,id=id[,prop[=value][,...]]\n"
810    "                latency= add extra latency to playback in microseconds\n"
811#endif
812#ifdef CONFIG_AUDIO_OSS
813    "-audiodev oss,id=id[,prop[=value][,...]]\n"
814    "                in|out.dev= path of the audio device to use\n"
815    "                in|out.buffer-count= number of buffers\n"
816    "                in|out.try-poll= attempt to use poll mode\n"
817    "                try-mmap= try using memory mapped access\n"
818    "                exclusive= open device in exclusive mode\n"
819    "                dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
820#endif
821#ifdef CONFIG_AUDIO_PA
822    "-audiodev pa,id=id[,prop[=value][,...]]\n"
823    "                server= PulseAudio server address\n"
824    "                in|out.name= source/sink device name\n"
825    "                in|out.latency= desired latency in microseconds\n"
826#endif
827#ifdef CONFIG_AUDIO_PIPEWIRE
828    "-audiodev pipewire,id=id[,prop[=value][,...]]\n"
829    "                in|out.name= source/sink device name\n"
830    "                in|out.stream-name= name of pipewire stream\n"
831    "                in|out.latency= desired latency in microseconds\n"
832#endif
833#ifdef CONFIG_AUDIO_SDL
834    "-audiodev sdl,id=id[,prop[=value][,...]]\n"
835    "                in|out.buffer-count= number of buffers\n"
836#endif
837#ifdef CONFIG_AUDIO_SNDIO
838    "-audiodev sndio,id=id[,prop[=value][,...]]\n"
839#endif
840#ifdef CONFIG_SPICE
841    "-audiodev spice,id=id[,prop[=value][,...]]\n"
842#endif
843#ifdef CONFIG_DBUS_DISPLAY
844    "-audiodev dbus,id=id[,prop[=value][,...]]\n"
845#endif
846    "-audiodev wav,id=id[,prop[=value][,...]]\n"
847    "                path= path of wav file to record\n",
848    QEMU_ARCH_ALL)
849SRST
850``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
851    Adds a new audio backend driver identified by id. There are global
852    and driver specific properties. Some values can be set differently
853    for input and output, they're marked with ``in|out.``. You can set
854    the input's property with ``in.prop`` and the output's property with
855    ``out.prop``. For example:
856
857    ::
858
859        -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
860        -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
861
862    NOTE: parameter validation is known to be incomplete, in many cases
863    specifying an invalid option causes QEMU to print an error message
864    and continue emulation without sound.
865
866    Valid global options are:
867
868    ``id=identifier``
869        Identifies the audio backend.
870
871    ``timer-period=period``
872        Sets the timer period used by the audio subsystem in
873        microseconds. Default is 10000 (10 ms).
874
875    ``in|out.mixing-engine=on|off``
876        Use QEMU's mixing engine to mix all streams inside QEMU and
877        convert audio formats when not supported by the backend. When
878        off, fixed-settings must be off too. Note that disabling this
879        option means that the selected backend must support multiple
880        streams and the audio formats used by the virtual cards,
881        otherwise you'll get no sound. It's not recommended to disable
882        this option unless you want to use 5.1 or 7.1 audio, as mixing
883        engine only supports mono and stereo audio. Default is on.
884
885    ``in|out.fixed-settings=on|off``
886        Use fixed settings for host audio. When off, it will change
887        based on how the guest opens the sound card. In this case you
888        must not specify frequency, channels or format. Default is on.
889
890    ``in|out.frequency=frequency``
891        Specify the frequency to use when using fixed-settings. Default
892        is 44100Hz.
893
894    ``in|out.channels=channels``
895        Specify the number of channels to use when using fixed-settings.
896        Default is 2 (stereo).
897
898    ``in|out.format=format``
899        Specify the sample format to use when using fixed-settings.
900        Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
901        ``u32``, ``f32``. Default is ``s16``.
902
903    ``in|out.voices=voices``
904        Specify the number of voices to use. Default is 1.
905
906    ``in|out.buffer-length=usecs``
907        Sets the size of the buffer in microseconds.
908
909``-audiodev none,id=id[,prop[=value][,...]]``
910    Creates a dummy backend that discards all outputs. This backend has
911    no backend specific properties.
912
913``-audiodev alsa,id=id[,prop[=value][,...]]``
914    Creates backend using the ALSA. This backend is only available on
915    Linux.
916
917    ALSA specific options are:
918
919    ``in|out.dev=device``
920        Specify the ALSA device to use for input and/or output. Default
921        is ``default``.
922
923    ``in|out.period-length=usecs``
924        Sets the period length in microseconds.
925
926    ``in|out.try-poll=on|off``
927        Attempt to use poll mode with the device. Default is on.
928
929    ``threshold=threshold``
930        Threshold (in microseconds) when playback starts. Default is 0.
931
932``-audiodev coreaudio,id=id[,prop[=value][,...]]``
933    Creates a backend using Apple's Core Audio. This backend is only
934    available on Mac OS and only supports playback.
935
936    Core Audio specific options are:
937
938    ``in|out.buffer-count=count``
939        Sets the count of the buffers.
940
941``-audiodev dsound,id=id[,prop[=value][,...]]``
942    Creates a backend using Microsoft's DirectSound. This backend is
943    only available on Windows and only supports playback.
944
945    DirectSound specific options are:
946
947    ``latency=usecs``
948        Add extra usecs microseconds latency to playback. Default is
949        10000 (10 ms).
950
951``-audiodev oss,id=id[,prop[=value][,...]]``
952    Creates a backend using OSS. This backend is available on most
953    Unix-like systems.
954
955    OSS specific options are:
956
957    ``in|out.dev=device``
958        Specify the file name of the OSS device to use. Default is
959        ``/dev/dsp``.
960
961    ``in|out.buffer-count=count``
962        Sets the count of the buffers.
963
964    ``in|out.try-poll=on|of``
965        Attempt to use poll mode with the device. Default is on.
966
967    ``try-mmap=on|off``
968        Try using memory mapped device access. Default is off.
969
970    ``exclusive=on|off``
971        Open the device in exclusive mode (vmix won't work in this
972        case). Default is off.
973
974    ``dsp-policy=policy``
975        Sets the timing policy (between 0 and 10, where smaller number
976        means smaller latency but higher CPU usage). Use -1 to use
977        buffer sizes specified by ``buffer`` and ``buffer-count``. This
978        option is ignored if you do not have OSS 4. Default is 5.
979
980``-audiodev pa,id=id[,prop[=value][,...]]``
981    Creates a backend using PulseAudio. This backend is available on
982    most systems.
983
984    PulseAudio specific options are:
985
986    ``server=server``
987        Sets the PulseAudio server to connect to.
988
989    ``in|out.name=sink``
990        Use the specified source/sink for recording/playback.
991
992    ``in|out.latency=usecs``
993        Desired latency in microseconds. The PulseAudio server will try
994        to honor this value but actual latencies may be lower or higher.
995
996``-audiodev pipewire,id=id[,prop[=value][,...]]``
997    Creates a backend using PipeWire. This backend is available on
998    most systems.
999
1000    PipeWire specific options are:
1001
1002    ``in|out.latency=usecs``
1003        Desired latency in microseconds.
1004
1005    ``in|out.name=sink``
1006        Use the specified source/sink for recording/playback.
1007
1008    ``in|out.stream-name``
1009        Specify the name of pipewire stream.
1010
1011``-audiodev sdl,id=id[,prop[=value][,...]]``
1012    Creates a backend using SDL. This backend is available on most
1013    systems, but you should use your platform's native backend if
1014    possible.
1015
1016    SDL specific options are:
1017
1018    ``in|out.buffer-count=count``
1019        Sets the count of the buffers.
1020
1021``-audiodev sndio,id=id[,prop[=value][,...]]``
1022    Creates a backend using SNDIO. This backend is available on
1023    OpenBSD and most other Unix-like systems.
1024
1025    Sndio specific options are:
1026
1027    ``in|out.dev=device``
1028        Specify the sndio device to use for input and/or output. Default
1029        is ``default``.
1030
1031    ``in|out.latency=usecs``
1032        Sets the desired period length in microseconds.
1033
1034``-audiodev spice,id=id[,prop[=value][,...]]``
1035    Creates a backend that sends audio through SPICE. This backend
1036    requires ``-spice`` and automatically selected in that case, so
1037    usually you can ignore this option. This backend has no backend
1038    specific properties.
1039
1040``-audiodev wav,id=id[,prop[=value][,...]]``
1041    Creates a backend that writes audio to a WAV file.
1042
1043    Backend specific options are:
1044
1045    ``path=path``
1046        Write recorded audio into the specified file. Default is
1047        ``qemu.wav``.
1048ERST
1049
1050DEF("device", HAS_ARG, QEMU_OPTION_device,
1051    "-device driver[,prop[=value][,...]]\n"
1052    "                add device (based on driver)\n"
1053    "                prop=value,... sets driver properties\n"
1054    "                use '-device help' to print all possible drivers\n"
1055    "                use '-device driver,help' to print all possible properties\n",
1056    QEMU_ARCH_ALL)
1057SRST
1058``-device driver[,prop[=value][,...]]``
1059    Add device driver. prop=value sets driver properties. Valid
1060    properties depend on the driver. To get help on possible drivers and
1061    properties, use ``-device help`` and ``-device driver,help``.
1062
1063    Some drivers are:
1064
1065``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]``
1066    Add an IPMI BMC. This is a simulation of a hardware management
1067    interface processor that normally sits on a system. It provides a
1068    watchdog and the ability to reset and power control the system. You
1069    need to connect this to an IPMI interface to make it useful
1070
1071    The IPMI slave address to use for the BMC. The default is 0x20. This
1072    address is the BMC's address on the I2C network of management
1073    controllers. If you don't know what this means, it is safe to ignore
1074    it.
1075
1076    ``id=id``
1077        The BMC id for interfaces to use this device.
1078
1079    ``slave_addr=val``
1080        Define slave address to use for the BMC. The default is 0x20.
1081
1082    ``sdrfile=file``
1083        file containing raw Sensor Data Records (SDR) data. The default
1084        is none.
1085
1086    ``fruareasize=val``
1087        size of a Field Replaceable Unit (FRU) area. The default is
1088        1024.
1089
1090    ``frudatafile=file``
1091        file containing raw Field Replaceable Unit (FRU) inventory data.
1092        The default is none.
1093
1094    ``guid=uuid``
1095        value for the GUID for the BMC, in standard UUID format. If this
1096        is set, get "Get GUID" command to the BMC will return it.
1097        Otherwise "Get GUID" will return an error.
1098
1099``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
1100    Add a connection to an external IPMI BMC simulator. Instead of
1101    locally emulating the BMC like the above item, instead connect to an
1102    external entity that provides the IPMI services.
1103
1104    A connection is made to an external BMC simulator. If you do this,
1105    it is strongly recommended that you use the "reconnect=" chardev
1106    option to reconnect to the simulator if the connection is lost. Note
1107    that if this is not used carefully, it can be a security issue, as
1108    the interface has the ability to send resets, NMIs, and power off
1109    the VM. It's best if QEMU makes a connection to an external
1110    simulator running on a secure port on localhost, so neither the
1111    simulator nor QEMU is exposed to any outside network.
1112
1113    See the "lanserv/README.vm" file in the OpenIPMI library for more
1114    details on the external interface.
1115
1116``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
1117    Add a KCS IPMI interface on the ISA bus. This also adds a
1118    corresponding ACPI and SMBIOS entries, if appropriate.
1119
1120    ``bmc=id``
1121        The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
1122        above.
1123
1124    ``ioport=val``
1125        Define the I/O address of the interface. The default is 0xca0
1126        for KCS.
1127
1128    ``irq=val``
1129        Define the interrupt to use. The default is 5. To disable
1130        interrupts, set this to 0.
1131
1132``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
1133    Like the KCS interface, but defines a BT interface. The default port
1134    is 0xe4 and the default interrupt is 5.
1135
1136``-device pci-ipmi-kcs,bmc=id``
1137    Add a KCS IPMI interface on the PCI bus.
1138
1139    ``bmc=id``
1140        The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
1141
1142``-device pci-ipmi-bt,bmc=id``
1143    Like the KCS interface, but defines a BT interface on the PCI bus.
1144
1145``-device intel-iommu[,option=...]``
1146    This is only supported by ``-machine q35``, which will enable Intel VT-d
1147    emulation within the guest.  It supports below options:
1148
1149    ``intremap=on|off`` (default: auto)
1150        This enables interrupt remapping feature.  It's required to enable
1151        complete x2apic.  Currently it only supports kvm kernel-irqchip modes
1152        ``off`` or ``split``, while full kernel-irqchip is not yet supported.
1153        The default value is "auto", which will be decided by the mode of
1154        kernel-irqchip.
1155
1156    ``caching-mode=on|off`` (default: off)
1157        This enables caching mode for the VT-d emulated device.  When
1158        caching-mode is enabled, each guest DMA buffer mapping will generate an
1159        IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in
1160        a synchronous way.  It is required for ``-device vfio-pci`` to work
1161        with the VT-d device, because host assigned devices requires to setup
1162        the DMA mapping on the host before guest DMA starts.
1163
1164    ``device-iotlb=on|off`` (default: off)
1165        This enables device-iotlb capability for the emulated VT-d device.  So
1166        far virtio/vhost should be the only real user for this parameter,
1167        paired with ats=on configured for the device.
1168
1169    ``aw-bits=39|48`` (default: 39)
1170        This decides the address width of IOVA address space.  The address
1171        space has 39 bits width for 3-level IOMMU page tables, and 48 bits for
1172        4-level IOMMU page tables.
1173
1174    Please also refer to the wiki page for general scenarios of VT-d
1175    emulation in QEMU: https://wiki.qemu.org/Features/VT-d.
1176
1177``-device virtio-iommu-pci[,option=...]``
1178    This is only supported by ``-machine q35`` (x86_64) and ``-machine virt`` (ARM).
1179    It supports below options:
1180
1181    ``granule=val`` (possible values are 4k, 8k, 16k, 64k and host; default: host)
1182        This decides the default granule to be be exposed by the
1183        virtio-iommu. If host, the granule matches the host page size.
1184
1185    ``aw-bits=val`` (val between 32 and 64, default depends on machine)
1186        This decides the address width of the IOVA address space.
1187
1188ERST
1189
1190DEF("name", HAS_ARG, QEMU_OPTION_name,
1191    "-name string1[,process=string2][,debug-threads=on|off]\n"
1192    "                set the name of the guest\n"
1193    "                string1 sets the window title and string2 the process name\n"
1194    "                When debug-threads is enabled, individual threads are given a separate name\n"
1195    "                NOTE: The thread names are for debugging and not a stable API.\n",
1196    QEMU_ARCH_ALL)
1197SRST
1198``-name name``
1199    Sets the name of the guest. This name will be displayed in the SDL
1200    window caption. The name will also be used for the VNC server. Also
1201    optionally set the top visible process name in Linux. Naming of
1202    individual threads can also be enabled on Linux to aid debugging.
1203ERST
1204
1205DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
1206    "-uuid %08x-%04x-%04x-%04x-%012x\n"
1207    "                specify machine UUID\n", QEMU_ARCH_ALL)
1208SRST
1209``-uuid uuid``
1210    Set system UUID.
1211ERST
1212
1213DEFHEADING()
1214
1215DEFHEADING(Block device options:)
1216
1217SRST
1218The QEMU block device handling options have a long history and
1219have gone through several iterations as the feature set and complexity
1220of the block layer have grown. Many online guides to QEMU often
1221reference older and deprecated options, which can lead to confusion.
1222
1223The most explicit way to describe disks is to use a combination of
1224``-device`` to specify the hardware device and ``-blockdev`` to
1225describe the backend. The device defines what the guest sees and the
1226backend describes how QEMU handles the data. It is the only guaranteed
1227stable interface for describing block devices and as such is
1228recommended for management tools and scripting.
1229
1230The ``-drive`` option combines the device and backend into a single
1231command line option which is a more human friendly. There is however no
1232interface stability guarantee although some older board models still
1233need updating to work with the modern blockdev forms.
1234
1235Older options like ``-hda`` are essentially macros which expand into
1236``-drive`` options for various drive interfaces. The original forms
1237bake in a lot of assumptions from the days when QEMU was emulating a
1238legacy PC, they are not recommended for modern configurations.
1239
1240ERST
1241
1242DEF("fda", HAS_ARG, QEMU_OPTION_fda,
1243    "-fda/-fdb file  use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
1244DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
1245SRST
1246``-fda file``
1247  \
1248``-fdb file``
1249    Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in
1250    the System Emulation Users Guide).
1251ERST
1252
1253DEF("hda", HAS_ARG, QEMU_OPTION_hda,
1254    "-hda/-hdb file  use 'file' as hard disk 0/1 image\n", QEMU_ARCH_ALL)
1255DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
1256DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
1257    "-hdc/-hdd file  use 'file' as hard disk 2/3 image\n", QEMU_ARCH_ALL)
1258DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
1259SRST
1260``-hda file``
1261  \
1262``-hdb file``
1263  \
1264``-hdc file``
1265  \
1266``-hdd file``
1267    Use file as hard disk 0, 1, 2 or 3 image on the default bus of the
1268    emulated machine (this is for example the IDE bus on most x86 machines,
1269    but it can also be SCSI, virtio or something else on other target
1270    architectures). See also the :ref:`disk images` chapter in the System
1271    Emulation Users Guide.
1272ERST
1273
1274DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
1275    "-cdrom file     use 'file' as CD-ROM image\n",
1276    QEMU_ARCH_ALL)
1277SRST
1278``-cdrom file``
1279    Use file as CD-ROM image on the default bus of the emulated machine
1280    (which is IDE1 master on x86, so you cannot use ``-hdc`` and ``-cdrom``
1281    at the same time there). On systems that support it, you can use the
1282    host CD-ROM by using ``/dev/cdrom`` as filename.
1283ERST
1284
1285DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
1286    "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
1287    "          [,cache.direct=on|off][,cache.no-flush=on|off]\n"
1288    "          [,read-only=on|off][,auto-read-only=on|off]\n"
1289    "          [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
1290    "          [,driver specific parameters...]\n"
1291    "                configure a block backend\n", QEMU_ARCH_ALL)
1292SRST
1293``-blockdev option[,option[,option[,...]]]``
1294    Define a new block driver node. Some of the options apply to all
1295    block drivers, other options are only accepted for a specific block
1296    driver. See below for a list of generic options and options for the
1297    most common block drivers.
1298
1299    Options that expect a reference to another node (e.g. ``file``) can
1300    be given in two ways. Either you specify the node name of an already
1301    existing node (file=node-name), or you define a new node inline,
1302    adding options for the referenced node after a dot
1303    (file.filename=path,file.aio=native).
1304
1305    A block driver node created with ``-blockdev`` can be used for a
1306    guest device by specifying its node name for the ``drive`` property
1307    in a ``-device`` argument that defines a block device.
1308
1309    ``Valid options for any block driver node:``
1310        ``driver``
1311            Specifies the block driver to use for the given node.
1312
1313        ``node-name``
1314            This defines the name of the block driver node by which it
1315            will be referenced later. The name must be unique, i.e. it
1316            must not match the name of a different block driver node, or
1317            (if you use ``-drive`` as well) the ID of a drive.
1318
1319            If no node name is specified, it is automatically generated.
1320            The generated node name is not intended to be predictable
1321            and changes between QEMU invocations. For the top level, an
1322            explicit node name must be specified.
1323
1324        ``read-only``
1325            Open the node read-only. Guest write attempts will fail.
1326
1327            Note that some block drivers support only read-only access,
1328            either generally or in certain configurations. In this case,
1329            the default value ``read-only=off`` does not work and the
1330            option must be specified explicitly.
1331
1332        ``auto-read-only``
1333            If ``auto-read-only=on`` is set, QEMU may fall back to
1334            read-only usage even when ``read-only=off`` is requested, or
1335            even switch between modes as needed, e.g. depending on
1336            whether the image file is writable or whether a writing user
1337            is attached to the node.
1338
1339        ``force-share``
1340            Override the image locking system of QEMU by forcing the
1341            node to utilize weaker shared access for permissions where
1342            it would normally request exclusive access. When there is
1343            the potential for multiple instances to have the same file
1344            open (whether this invocation of QEMU is the first or the
1345            second instance), both instances must permit shared access
1346            for the second instance to succeed at opening the file.
1347
1348            Enabling ``force-share=on`` requires ``read-only=on``.
1349
1350        ``cache.direct``
1351            The host page cache can be avoided with ``cache.direct=on``.
1352            This will attempt to do disk IO directly to the guest's
1353            memory. QEMU may still perform an internal copy of the data.
1354
1355        ``cache.no-flush``
1356            In case you don't care about data integrity over host
1357            failures, you can use ``cache.no-flush=on``. This option
1358            tells QEMU that it never needs to write any data to the disk
1359            but can instead keep things in cache. If anything goes
1360            wrong, like your host losing power, the disk storage getting
1361            disconnected accidentally, etc. your image will most
1362            probably be rendered unusable.
1363
1364        ``discard=discard``
1365            discard is one of "ignore" (or "off") or "unmap" (or "on")
1366            and controls whether ``discard`` (also known as ``trim`` or
1367            ``unmap``) requests are ignored or passed to the filesystem.
1368            Some machine types may not support discard requests.
1369
1370        ``detect-zeroes=detect-zeroes``
1371            detect-zeroes is "off", "on" or "unmap" and enables the
1372            automatic conversion of plain zero writes by the OS to
1373            driver specific optimized zero write commands. You may even
1374            choose "unmap" if discard is set to "unmap" to allow a zero
1375            write to be converted to an ``unmap`` operation.
1376
1377    ``Driver-specific options for file``
1378        This is the protocol-level block driver for accessing regular
1379        files.
1380
1381        ``filename``
1382            The path to the image file in the local filesystem
1383
1384        ``aio``
1385            Specifies the AIO backend (threads/native/io_uring,
1386            default: threads)
1387
1388        ``locking``
1389            Specifies whether the image file is protected with Linux OFD
1390            / POSIX locks. The default is to use the Linux Open File
1391            Descriptor API if available, otherwise no lock is applied.
1392            (auto/on/off, default: auto)
1393
1394        Example:
1395
1396        ::
1397
1398            -blockdev driver=file,node-name=disk,filename=disk.img
1399
1400    ``Driver-specific options for raw``
1401        This is the image format block driver for raw images. It is
1402        usually stacked on top of a protocol level block driver such as
1403        ``file``.
1404
1405        ``file``
1406            Reference to or definition of the data source block driver
1407            node (e.g. a ``file`` driver node)
1408
1409        Example 1:
1410
1411        ::
1412
1413            -blockdev driver=file,node-name=disk_file,filename=disk.img
1414            -blockdev driver=raw,node-name=disk,file=disk_file
1415
1416        Example 2:
1417
1418        ::
1419
1420            -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1421
1422    ``Driver-specific options for qcow2``
1423        This is the image format block driver for qcow2 images. It is
1424        usually stacked on top of a protocol level block driver such as
1425        ``file``.
1426
1427        ``file``
1428            Reference to or definition of the data source block driver
1429            node (e.g. a ``file`` driver node)
1430
1431        ``backing``
1432            Reference to or definition of the backing file block device
1433            (default is taken from the image file). It is allowed to
1434            pass ``null`` here in order to disable the default backing
1435            file.
1436
1437        ``lazy-refcounts``
1438            Whether to enable the lazy refcounts feature (on/off;
1439            default is taken from the image file)
1440
1441        ``cache-size``
1442            The maximum total size of the L2 table and refcount block
1443            caches in bytes (default: the sum of l2-cache-size and
1444            refcount-cache-size)
1445
1446        ``l2-cache-size``
1447            The maximum size of the L2 table cache in bytes (default: if
1448            cache-size is not specified - 32M on Linux platforms, and 8M
1449            on non-Linux platforms; otherwise, as large as possible
1450            within the cache-size, while permitting the requested or the
1451            minimal refcount cache size)
1452
1453        ``refcount-cache-size``
1454            The maximum size of the refcount block cache in bytes
1455            (default: 4 times the cluster size; or if cache-size is
1456            specified, the part of it which is not used for the L2
1457            cache)
1458
1459        ``cache-clean-interval``
1460            Clean unused entries in the L2 and refcount caches. The
1461            interval is in seconds. The default value is 600 on
1462            supporting platforms, and 0 on other platforms. Setting it
1463            to 0 disables this feature.
1464
1465        ``pass-discard-request``
1466            Whether discard requests to the qcow2 device should be
1467            forwarded to the data source (on/off; default: on if
1468            discard=unmap is specified, off otherwise)
1469
1470        ``pass-discard-snapshot``
1471            Whether discard requests for the data source should be
1472            issued when a snapshot operation (e.g. deleting a snapshot)
1473            frees clusters in the qcow2 file (on/off; default: on)
1474
1475        ``pass-discard-other``
1476            Whether discard requests for the data source should be
1477            issued on other occasions where a cluster gets freed
1478            (on/off; default: off)
1479
1480        ``discard-no-unref``
1481            When enabled, data clusters will remain preallocated when they are
1482            no longer used, e.g. because they are discarded or converted to
1483            zero clusters. As usual, whether the old data is discarded or kept
1484            on the protocol level (i.e. in the image file) depends on the
1485            setting of the pass-discard-request option. Keeping the clusters
1486            preallocated prevents qcow2 fragmentation that would otherwise be
1487            caused by freeing and re-allocating them later. Besides potential
1488            performance degradation, such fragmentation can lead to increased
1489            allocation of clusters past the end of the image file,
1490            resulting in image files whose file length can grow much larger
1491            than their guest disk size would suggest.
1492            If image file length is of concern (e.g. when storing qcow2
1493            images directly on block devices), you should consider enabling
1494            this option.
1495
1496        ``overlap-check``
1497            Which overlap checks to perform for writes to the image
1498            (none/constant/cached/all; default: cached). For details or
1499            finer granularity control refer to the QAPI documentation of
1500            ``blockdev-add``.
1501
1502        Example 1:
1503
1504        ::
1505
1506            -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1507            -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1508
1509        Example 2:
1510
1511        ::
1512
1513            -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1514
1515    ``Driver-specific options for other drivers``
1516        Please refer to the QAPI documentation of the ``blockdev-add``
1517        QMP command.
1518ERST
1519
1520DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1521    "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1522    "       [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1523    "       [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1524    "       [,werror=ignore|stop|report|enospc][,id=name]\n"
1525    "       [,aio=threads|native|io_uring]\n"
1526    "       [,readonly=on|off][,copy-on-read=on|off]\n"
1527    "       [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1528    "       [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1529    "       [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1530    "       [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1531    "       [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1532    "       [[,iops_size=is]]\n"
1533    "       [[,group=g]]\n"
1534    "                use 'file' as a drive image\n", QEMU_ARCH_ALL)
1535SRST
1536``-drive option[,option[,option[,...]]]``
1537    Define a new drive. This includes creating a block driver node (the
1538    backend) as well as a guest device, and is mostly a shortcut for
1539    defining the corresponding ``-blockdev`` and ``-device`` options.
1540
1541    ``-drive`` accepts all options that are accepted by ``-blockdev``.
1542    In addition, it knows the following options:
1543
1544    ``file=file``
1545        This option defines which disk image (see the :ref:`disk images`
1546        chapter in the System Emulation Users Guide) to use with this drive.
1547        If the filename contains comma, you must double it (for instance,
1548        "file=my,,file" to use file "my,file").
1549
1550        Special files such as iSCSI devices can be specified using
1551        protocol specific URLs. See the section for "Device URL Syntax"
1552        for more information.
1553
1554    ``if=interface``
1555        This option defines on which type on interface the drive is
1556        connected. Available types are: ide, scsi, sd, mtd, floppy,
1557        pflash, virtio, none.
1558
1559    ``bus=bus,unit=unit``
1560        These options define where is connected the drive by defining
1561        the bus number and the unit id.
1562
1563    ``index=index``
1564        This option defines where the drive is connected by using an
1565        index in the list of available connectors of a given interface
1566        type.
1567
1568    ``media=media``
1569        This option defines the type of the media: disk or cdrom.
1570
1571    ``snapshot=snapshot``
1572        snapshot is "on" or "off" and controls snapshot mode for the
1573        given drive (see ``-snapshot``).
1574
1575    ``cache=cache``
1576        cache is "none", "writeback", "unsafe", "directsync" or
1577        "writethrough" and controls how the host cache is used to access
1578        block data. This is a shortcut that sets the ``cache.direct``
1579        and ``cache.no-flush`` options (as in ``-blockdev``), and
1580        additionally ``cache.writeback``, which provides a default for
1581        the ``write-cache`` option of block guest devices (as in
1582        ``-device``). The modes correspond to the following settings:
1583
1584        =============  ===============   ============   ==============
1585        \              cache.writeback   cache.direct   cache.no-flush
1586        =============  ===============   ============   ==============
1587        writeback      on                off            off
1588        none           on                on             off
1589        writethrough   off               off            off
1590        directsync     off               on             off
1591        unsafe         on                off            on
1592        =============  ===============   ============   ==============
1593
1594        The default mode is ``cache=writeback``.
1595
1596    ``aio=aio``
1597        aio is "threads", "native", or "io_uring" and selects between pthread
1598        based disk I/O, native Linux AIO, or Linux io_uring API.
1599
1600    ``format=format``
1601        Specify which disk format will be used rather than detecting the
1602        format. Can be used to specify format=raw to avoid interpreting
1603        an untrusted format header.
1604
1605    ``werror=action,rerror=action``
1606        Specify which action to take on write and read errors. Valid
1607        actions are: "ignore" (ignore the error and try to continue),
1608        "stop" (pause QEMU), "report" (report the error to the guest),
1609        "enospc" (pause QEMU only if the host disk is full; report the
1610        error to the guest otherwise). The default setting is
1611        ``werror=enospc`` and ``rerror=report``.
1612
1613    ``copy-on-read=copy-on-read``
1614        copy-on-read is "on" or "off" and enables whether to copy read
1615        backing file sectors into the image file.
1616
1617    ``bps=b,bps_rd=r,bps_wr=w``
1618        Specify bandwidth throttling limits in bytes per second, either
1619        for all request types or for reads or writes only. Small values
1620        can lead to timeouts or hangs inside the guest. A safe minimum
1621        for disks is 2 MB/s.
1622
1623    ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
1624        Specify bursts in bytes per second, either for all request types
1625        or for reads or writes only. Bursts allow the guest I/O to spike
1626        above the limit temporarily.
1627
1628    ``iops=i,iops_rd=r,iops_wr=w``
1629        Specify request rate limits in requests per second, either for
1630        all request types or for reads or writes only.
1631
1632    ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
1633        Specify bursts in requests per second, either for all request
1634        types or for reads or writes only. Bursts allow the guest I/O to
1635        spike above the limit temporarily.
1636
1637    ``iops_size=is``
1638        Let every is bytes of a request count as a new request for iops
1639        throttling purposes. Use this option to prevent guests from
1640        circumventing iops limits by sending fewer but larger requests.
1641
1642    ``group=g``
1643        Join a throttling quota group with given name g. All drives that
1644        are members of the same group are accounted for together. Use
1645        this option to prevent guests from circumventing throttling
1646        limits by using many small disks instead of a single larger
1647        disk.
1648
1649    By default, the ``cache.writeback=on`` mode is used. It will report
1650    data writes as completed as soon as the data is present in the host
1651    page cache. This is safe as long as your guest OS makes sure to
1652    correctly flush disk caches where needed. If your guest OS does not
1653    handle volatile disk write caches correctly and your host crashes or
1654    loses power, then the guest may experience data corruption.
1655
1656    For such guests, you should consider using ``cache.writeback=off``.
1657    This means that the host page cache will be used to read and write
1658    data, but write notification will be sent to the guest only after
1659    QEMU has made sure to flush each write to the disk. Be aware that
1660    this has a major impact on performance.
1661
1662    When using the ``-snapshot`` option, unsafe caching is always used.
1663
1664    Copy-on-read avoids accessing the same backing file sectors
1665    repeatedly and is useful when the backing file is over a slow
1666    network. By default copy-on-read is off.
1667
1668    Instead of ``-cdrom`` you can use:
1669
1670    .. parsed-literal::
1671
1672        |qemu_system| -drive file=file,index=2,media=cdrom
1673
1674    Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:
1675
1676    .. parsed-literal::
1677
1678        |qemu_system| -drive file=file,index=0,media=disk
1679        |qemu_system| -drive file=file,index=1,media=disk
1680        |qemu_system| -drive file=file,index=2,media=disk
1681        |qemu_system| -drive file=file,index=3,media=disk
1682
1683    You can open an image using pre-opened file descriptors from an fd
1684    set:
1685
1686    .. parsed-literal::
1687
1688        |qemu_system| \\
1689         -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
1690         -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
1691         -drive file=/dev/fdset/2,index=0,media=disk
1692
1693    You can connect a CDROM to the slave of ide0:
1694
1695    .. parsed-literal::
1696
1697        |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom
1698
1699    If you don't specify the "file=" argument, you define an empty
1700    drive:
1701
1702    .. parsed-literal::
1703
1704        |qemu_system_x86| -drive if=ide,index=1,media=cdrom
1705
1706    Instead of ``-fda``, ``-fdb``, you can use:
1707
1708    .. parsed-literal::
1709
1710        |qemu_system_x86| -drive file=file,index=0,if=floppy
1711        |qemu_system_x86| -drive file=file,index=1,if=floppy
1712
1713    By default, interface is "ide" and index is automatically
1714    incremented:
1715
1716    .. parsed-literal::
1717
1718        |qemu_system_x86| -drive file=a -drive file=b
1719
1720    is interpreted like:
1721
1722    .. parsed-literal::
1723
1724        |qemu_system_x86| -hda a -hdb b
1725ERST
1726
1727DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1728    "-mtdblock file  use 'file' as on-board Flash memory image\n",
1729    QEMU_ARCH_ALL)
1730SRST
1731``-mtdblock file``
1732    Use file as on-board Flash memory image.
1733ERST
1734
1735DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1736    "-sd file        use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1737SRST
1738``-sd file``
1739    Use file as SecureDigital card image.
1740ERST
1741
1742DEF("snapshot", 0, QEMU_OPTION_snapshot,
1743    "-snapshot       write to temporary files instead of disk image files\n",
1744    QEMU_ARCH_ALL)
1745SRST
1746``-snapshot``
1747    Write to temporary files instead of disk image files. In this case,
1748    the raw disk image you use is not written back. You can however
1749    force the write back by pressing C-a s (see the :ref:`disk images`
1750    chapter in the System Emulation Users Guide).
1751
1752    .. warning::
1753       snapshot is incompatible with ``-blockdev`` (instead use qemu-img
1754       to manually create snapshot images to attach to your blockdev).
1755       If you have mixed ``-blockdev`` and ``-drive`` declarations you
1756       can use the 'snapshot' property on your drive declarations
1757       instead of this global option.
1758
1759ERST
1760
1761DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1762    "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1763    " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n"
1764    " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1765    " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1766    " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1767    " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1768    " [[,throttling.iops-size=is]]\n"
1769    "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n"
1770    "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n"
1771    "-fsdev synth,id=id\n",
1772    QEMU_ARCH_ALL)
1773
1774SRST
1775``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]``
1776  \
1777``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]``
1778  \
1779``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]``
1780  \
1781``-fsdev synth,id=id[,readonly=on]``
1782    Define a new file system device. Valid options are:
1783
1784    ``local``
1785        Accesses to the filesystem are done by QEMU.
1786
1787    ``proxy``
1788        Accesses to the filesystem are done by virtfs-proxy-helper(1). This
1789        option is deprecated (since QEMU 8.1) and will be removed in a future
1790        version of QEMU. Use ``local`` instead.
1791
1792    ``synth``
1793        Synthetic filesystem, only used by QTests.
1794
1795    ``id=id``
1796        Specifies identifier for this device.
1797
1798    ``path=path``
1799        Specifies the export path for the file system device. Files
1800        under this path will be available to the 9p client on the guest.
1801
1802    ``security_model=security_model``
1803        Specifies the security model to be used for this export path.
1804        Supported security models are "passthrough", "mapped-xattr",
1805        "mapped-file" and "none". In "passthrough" security model, files
1806        are stored using the same credentials as they are created on the
1807        guest. This requires QEMU to run as root. In "mapped-xattr"
1808        security model, some of the file attributes like uid, gid, mode
1809        bits and link target are stored as file attributes. For
1810        "mapped-file" these attributes are stored in the hidden
1811        .virtfs\_metadata directory. Directories exported by this
1812        security model cannot interact with other unix tools. "none"
1813        security model is same as passthrough except the sever won't
1814        report failures if it fails to set file attributes like
1815        ownership. Security model is mandatory only for local fsdriver.
1816        Other fsdrivers (like proxy) don't take security model as a
1817        parameter.
1818
1819    ``writeout=writeout``
1820        This is an optional argument. The only supported value is
1821        "immediate". This means that host page cache will be used to
1822        read and write data but write notification will be sent to the
1823        guest only when the data has been reported as written by the
1824        storage subsystem.
1825
1826    ``readonly=on``
1827        Enables exporting 9p share as a readonly mount for guests. By
1828        default read-write access is given.
1829
1830    ``socket=socket``
1831        Enables proxy filesystem driver to use passed socket file for
1832        communicating with virtfs-proxy-helper(1).
1833
1834    ``sock_fd=sock_fd``
1835        Enables proxy filesystem driver to use passed socket descriptor
1836        for communicating with virtfs-proxy-helper(1). Usually a helper
1837        like libvirt will create socketpair and pass one of the fds as
1838        sock\_fd.
1839
1840    ``fmode=fmode``
1841        Specifies the default mode for newly created files on the host.
1842        Works only with security models "mapped-xattr" and
1843        "mapped-file".
1844
1845    ``dmode=dmode``
1846        Specifies the default mode for newly created directories on the
1847        host. Works only with security models "mapped-xattr" and
1848        "mapped-file".
1849
1850    ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w``
1851        Specify bandwidth throttling limits in bytes per second, either
1852        for all request types or for reads or writes only.
1853
1854    ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm``
1855        Specify bursts in bytes per second, either for all request types
1856        or for reads or writes only. Bursts allow the guest I/O to spike
1857        above the limit temporarily.
1858
1859    ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w``
1860        Specify request rate limits in requests per second, either for
1861        all request types or for reads or writes only.
1862
1863    ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm``
1864        Specify bursts in requests per second, either for all request
1865        types or for reads or writes only. Bursts allow the guest I/O to
1866        spike above the limit temporarily.
1867
1868    ``throttling.iops-size=is``
1869        Let every is bytes of a request count as a new request for iops
1870        throttling purposes.
1871
1872    -fsdev option is used along with -device driver "virtio-9p-...".
1873
1874``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag``
1875    Options for virtio-9p-... driver are:
1876
1877    ``type``
1878        Specifies the variant to be used. Supported values are "pci",
1879        "ccw" or "device", depending on the machine type.
1880
1881    ``fsdev=id``
1882        Specifies the id value specified along with -fsdev option.
1883
1884    ``mount_tag=mount_tag``
1885        Specifies the tag name to be used by the guest to mount this
1886        export point.
1887ERST
1888
1889DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1890    "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1891    "        [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1892    "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n"
1893    "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n"
1894    "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n",
1895    QEMU_ARCH_ALL)
1896
1897SRST
1898``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]``
1899  \
1900``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1901  \
1902``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1903  \
1904``-virtfs synth,mount_tag=mount_tag``
1905    Define a new virtual filesystem device and expose it to the guest using
1906    a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain
1907    directory on host is made directly accessible by guest as a pass-through
1908    file system by using the 9P network protocol for communication between
1909    host and guests, if desired even accessible, shared by several guests
1910    simultaneously.
1911
1912    Note that ``-virtfs`` is actually just a convenience shortcut for its
1913    generalized form ``-fsdev -device virtio-9p-pci``.
1914
1915    The general form of pass-through file system options are:
1916
1917    ``local``
1918        Accesses to the filesystem are done by QEMU.
1919
1920    ``proxy``
1921        Accesses to the filesystem are done by virtfs-proxy-helper(1).
1922        This option is deprecated (since QEMU 8.1) and will be removed in a
1923        future version of QEMU. Use ``local`` instead.
1924
1925    ``synth``
1926        Synthetic filesystem, only used by QTests.
1927
1928    ``id=id``
1929        Specifies identifier for the filesystem device
1930
1931    ``path=path``
1932        Specifies the export path for the file system device. Files
1933        under this path will be available to the 9p client on the guest.
1934
1935    ``security_model=security_model``
1936        Specifies the security model to be used for this export path.
1937        Supported security models are "passthrough", "mapped-xattr",
1938        "mapped-file" and "none". In "passthrough" security model, files
1939        are stored using the same credentials as they are created on the
1940        guest. This requires QEMU to run as root. In "mapped-xattr"
1941        security model, some of the file attributes like uid, gid, mode
1942        bits and link target are stored as file attributes. For
1943        "mapped-file" these attributes are stored in the hidden
1944        .virtfs\_metadata directory. Directories exported by this
1945        security model cannot interact with other unix tools. "none"
1946        security model is same as passthrough except the sever won't
1947        report failures if it fails to set file attributes like
1948        ownership. Security model is mandatory only for local fsdriver.
1949        Other fsdrivers (like proxy) don't take security model as a
1950        parameter.
1951
1952    ``writeout=writeout``
1953        This is an optional argument. The only supported value is
1954        "immediate". This means that host page cache will be used to
1955        read and write data but write notification will be sent to the
1956        guest only when the data has been reported as written by the
1957        storage subsystem.
1958
1959    ``readonly=on``
1960        Enables exporting 9p share as a readonly mount for guests. By
1961        default read-write access is given.
1962
1963    ``socket=socket``
1964        Enables proxy filesystem driver to use passed socket file for
1965        communicating with virtfs-proxy-helper(1). Usually a helper like
1966        libvirt will create socketpair and pass one of the fds as
1967        sock\_fd.
1968
1969    ``sock_fd``
1970        Enables proxy filesystem driver to use passed 'sock\_fd' as the
1971        socket descriptor for interfacing with virtfs-proxy-helper(1).
1972
1973    ``fmode=fmode``
1974        Specifies the default mode for newly created files on the host.
1975        Works only with security models "mapped-xattr" and
1976        "mapped-file".
1977
1978    ``dmode=dmode``
1979        Specifies the default mode for newly created directories on the
1980        host. Works only with security models "mapped-xattr" and
1981        "mapped-file".
1982
1983    ``mount_tag=mount_tag``
1984        Specifies the tag name to be used by the guest to mount this
1985        export point.
1986
1987    ``multidevs=multidevs``
1988        Specifies how to deal with multiple devices being shared with a
1989        9p export. Supported behaviours are either "remap", "forbid" or
1990        "warn". The latter is the default behaviour on which virtfs 9p
1991        expects only one device to be shared with the same export, and
1992        if more than one device is shared and accessed via the same 9p
1993        export then only a warning message is logged (once) by qemu on
1994        host side. In order to avoid file ID collisions on guest you
1995        should either create a separate virtfs export for each device to
1996        be shared with guests (recommended way) or you might use "remap"
1997        instead which allows you to share multiple devices with only one
1998        export instead, which is achieved by remapping the original
1999        inode numbers from host to guest in a way that would prevent
2000        such collisions. Remapping inodes in such use cases is required
2001        because the original device IDs from host are never passed and
2002        exposed on guest. Instead all files of an export shared with
2003        virtfs always share the same device id on guest. So two files
2004        with identical inode numbers but from actually different devices
2005        on host would otherwise cause a file ID collision and hence
2006        potential misbehaviours on guest. "forbid" on the other hand
2007        assumes like "warn" that only one device is shared by the same
2008        export, however it will not only log a warning message but also
2009        deny access to additional devices on guest. Note though that
2010        "forbid" does currently not block all possible file access
2011        operations (e.g. readdir() would still return entries from other
2012        devices).
2013ERST
2014
2015DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
2016    "-iscsi [user=user][,password=password][,password-secret=secret-id]\n"
2017    "       [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE]\n"
2018    "       [,initiator-name=initiator-iqn][,id=target-iqn]\n"
2019    "       [,timeout=timeout]\n"
2020    "                iSCSI session parameters\n", QEMU_ARCH_ALL)
2021
2022SRST
2023``-iscsi``
2024    Configure iSCSI session parameters.
2025ERST
2026
2027DEFHEADING()
2028
2029DEFHEADING(USB convenience options:)
2030
2031DEF("usb", 0, QEMU_OPTION_usb,
2032    "-usb            enable on-board USB host controller (if not enabled by default)\n",
2033    QEMU_ARCH_ALL)
2034SRST
2035``-usb``
2036    Enable USB emulation on machine types with an on-board USB host
2037    controller (if not enabled by default). Note that on-board USB host
2038    controllers may not support USB 3.0. In this case
2039    ``-device qemu-xhci`` can be used instead on machines with PCI.
2040ERST
2041
2042DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
2043    "-usbdevice name add the host or guest USB device 'name'\n",
2044    QEMU_ARCH_ALL)
2045SRST
2046``-usbdevice devname``
2047    Add the USB device devname, and enable an on-board USB controller
2048    if possible and necessary (just like it can be done via
2049    ``-machine usb=on``). Note that this option is mainly intended for
2050    the user's convenience only. More fine-grained control can be
2051    achieved by selecting a USB host controller (if necessary) and the
2052    desired USB device via the ``-device`` option instead. For example,
2053    instead of using ``-usbdevice mouse`` it is possible to use
2054    ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse
2055    to a USB 3.0 controller instead (at least on machines that support
2056    PCI and do not have an USB controller enabled by default yet).
2057    For more details, see the chapter about
2058    :ref:`Connecting USB devices` in the System Emulation Users Guide.
2059    Possible devices for devname are:
2060
2061    ``braille``
2062        Braille device. This will use BrlAPI to display the braille
2063        output on a real or fake device (i.e. it also creates a
2064        corresponding ``braille`` chardev automatically beside the
2065        ``usb-braille`` USB device).
2066
2067    ``keyboard``
2068        Standard USB keyboard. Will override the PS/2 keyboard (if present).
2069
2070    ``mouse``
2071        Virtual Mouse. This will override the PS/2 mouse emulation when
2072        activated.
2073
2074    ``tablet``
2075        Pointer device that uses absolute coordinates (like a
2076        touchscreen). This means QEMU is able to report the mouse
2077        position without having to grab the mouse. Also overrides the
2078        PS/2 mouse emulation when activated.
2079
2080    ``wacom-tablet``
2081        Wacom PenPartner USB tablet.
2082
2083
2084ERST
2085
2086DEFHEADING()
2087
2088DEFHEADING(Display options:)
2089
2090DEF("display", HAS_ARG, QEMU_OPTION_display,
2091#if defined(CONFIG_SPICE)
2092    "-display spice-app[,gl=on|off]\n"
2093#endif
2094#if defined(CONFIG_SDL)
2095    "-display sdl[,gl=on|core|es|off][,grab-mod=<mod>][,show-cursor=on|off]\n"
2096    "            [,window-close=on|off]\n"
2097#endif
2098#if defined(CONFIG_GTK)
2099    "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
2100    "            [,show-tabs=on|off][,show-cursor=on|off][,window-close=on|off]\n"
2101    "            [,show-menubar=on|off][,zoom-to-fit=on|off]\n"
2102#endif
2103#if defined(CONFIG_VNC)
2104    "-display vnc=<display>[,<optargs>]\n"
2105#endif
2106#if defined(CONFIG_CURSES)
2107    "-display curses[,charset=<encoding>]\n"
2108#endif
2109#if defined(CONFIG_COCOA)
2110    "-display cocoa[,full-grab=on|off][,swap-opt-cmd=on|off]\n"
2111    "              [,show-cursor=on|off][,left-command-key=on|off]\n"
2112    "              [,full-screen=on|off][,zoom-to-fit=on|off]\n"
2113#endif
2114#if defined(CONFIG_OPENGL)
2115    "-display egl-headless[,rendernode=<file>]\n"
2116#endif
2117#if defined(CONFIG_DBUS_DISPLAY)
2118    "-display dbus[,addr=<dbusaddr>]\n"
2119    "             [,gl=on|core|es|off][,rendernode=<file>]\n"
2120#endif
2121    "-display none\n"
2122    "                select display backend type\n"
2123    "                The default display is equivalent to\n                "
2124#if defined(CONFIG_GTK)
2125            "\"-display gtk\"\n"
2126#elif defined(CONFIG_SDL)
2127            "\"-display sdl\"\n"
2128#elif defined(CONFIG_COCOA)
2129            "\"-display cocoa\"\n"
2130#elif defined(CONFIG_VNC)
2131            "\"-vnc localhost:0,to=99,id=default\"\n"
2132#else
2133            "\"-display none\"\n"
2134#endif
2135    , QEMU_ARCH_ALL)
2136SRST
2137``-display type``
2138    Select type of display to use. Use ``-display help`` to list the available
2139    display types. Valid values for type are
2140
2141    ``spice-app[,gl=on|off]``
2142        Start QEMU as a Spice server and launch the default Spice client
2143        application. The Spice server will redirect the serial consoles
2144        and QEMU monitors. (Since 4.0)
2145
2146    ``dbus``
2147        Export the display over D-Bus interfaces. (Since 7.0)
2148
2149        The connection is registered with the "org.qemu" name (and queued when
2150        already owned).
2151
2152        ``addr=<dbusaddr>`` : D-Bus bus address to connect to.
2153
2154        ``p2p=yes|no`` : Use peer-to-peer connection, accepted via QMP ``add_client``.
2155
2156        ``gl=on|off|core|es`` : Use OpenGL for rendering (the D-Bus interface
2157        will share framebuffers with DMABUF file descriptors).
2158
2159    ``sdl``
2160        Display video output via SDL (usually in a separate graphics
2161        window; see the SDL documentation for other possibilities).
2162        Valid parameters are:
2163
2164        ``grab-mod=<mods>`` : Used to select the modifier keys for toggling
2165        the mouse grabbing in conjunction with the "g" key. ``<mods>`` can be
2166        either ``lshift-lctrl-lalt`` or ``rctrl``.
2167
2168        ``gl=on|off|core|es`` : Use OpenGL for displaying
2169
2170        ``show-cursor=on|off`` :  Force showing the mouse cursor
2171
2172        ``window-close=on|off`` : Allow to quit qemu with window close button
2173
2174    ``gtk``
2175        Display video output in a GTK window. This interface provides
2176        drop-down menus and other UI elements to configure and control
2177        the VM during runtime. Valid parameters are:
2178
2179        ``full-screen=on|off`` : Start in fullscreen mode
2180
2181        ``gl=on|off`` : Use OpenGL for displaying
2182
2183        ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover
2184
2185        ``show-tabs=on|off`` : Display the tab bar for switching between the
2186                               various graphical interfaces (e.g. VGA and
2187                               virtual console character devices) by default.
2188
2189        ``show-cursor=on|off`` :  Force showing the mouse cursor
2190
2191        ``window-close=on|off`` : Allow to quit qemu with window close button
2192
2193        ``show-menubar=on|off`` : Display the main window menubar, defaults to "on"
2194
2195        ``zoom-to-fit=on|off`` : Expand video output to the window size,
2196                                 defaults to "off"
2197
2198    ``curses[,charset=<encoding>]``
2199        Display video output via curses. For graphics device models
2200        which support a text mode, QEMU can display this output using a
2201        curses/ncurses interface. Nothing is displayed when the graphics
2202        device is in graphical mode or if the graphics device does not
2203        support a text mode. Generally only the VGA device models
2204        support text mode. The font charset used by the guest can be
2205        specified with the ``charset`` option, for example
2206        ``charset=CP850`` for IBM CP850 encoding. The default is
2207        ``CP437``.
2208
2209    ``cocoa``
2210        Display video output in a Cocoa window. Mac only. This interface
2211        provides drop-down menus and other UI elements to configure and
2212        control the VM during runtime. Valid parameters are:
2213
2214        ``full-grab=on|off`` : Capture all key presses, including system combos.
2215                               This requires accessibility permissions, since it
2216                               performs a global grab on key events.
2217                               (default: off) See
2218                               https://support.apple.com/en-in/guide/mac-help/mh32356/mac
2219
2220        ``swap-opt-cmd=on|off`` : Swap the Option and Command keys so that their
2221                                  key codes match their position on non-Mac
2222                                  keyboards and you can use Meta/Super and Alt
2223                                  where you expect them.  (default: off)
2224
2225        ``show-cursor=on|off`` :  Force showing the mouse cursor
2226
2227        ``left-command-key=on|off`` : Disable forwarding left command key to host
2228
2229        ``full-screen=on|off`` : Start in fullscreen mode
2230
2231        ``zoom-to-fit=on|off`` : Expand video output to the window size,
2232                                 defaults to "off"
2233
2234    ``egl-headless[,rendernode=<file>]``
2235        Offload all OpenGL operations to a local DRI device. For any
2236        graphical display, this display needs to be paired with either
2237        VNC or SPICE displays.
2238
2239    ``vnc=<display>``
2240        Start a VNC server on display <display>
2241
2242    ``none``
2243        Do not display video output. The guest will still see an
2244        emulated graphics card, but its output will not be displayed to
2245        the QEMU user. This option differs from the -nographic option in
2246        that it only affects what is done with video output; -nographic
2247        also changes the destination of the serial and parallel port
2248        data.
2249ERST
2250
2251DEF("nographic", 0, QEMU_OPTION_nographic,
2252    "-nographic      disable graphical output and redirect serial I/Os to console\n",
2253    QEMU_ARCH_ALL)
2254SRST
2255``-nographic``
2256    Normally, if QEMU is compiled with graphical window support, it
2257    displays output such as guest graphics, guest console, and the QEMU
2258    monitor in a window. With this option, you can totally disable
2259    graphical output so that QEMU is a simple command line application.
2260    The emulated serial port is redirected on the console and muxed with
2261    the monitor (unless redirected elsewhere explicitly). Therefore, you
2262    can still use QEMU to debug a Linux kernel with a serial console.
2263    Use C-a h for help on switching between the console and monitor.
2264ERST
2265
2266#ifdef CONFIG_SPICE
2267DEF("spice", HAS_ARG, QEMU_OPTION_spice,
2268    "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
2269    "       [,x509-key-file=<file>][,x509-key-password=<file>]\n"
2270    "       [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
2271    "       [,x509-dh-key-file=<file>][,addr=addr]\n"
2272    "       [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n"
2273    "       [,tls-ciphers=<list>]\n"
2274    "       [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
2275    "       [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
2276    "       [,sasl=on|off][,disable-ticketing=on|off]\n"
2277    "       [,password-secret=<secret-id>]\n"
2278    "       [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
2279    "       [,jpeg-wan-compression=[auto|never|always]]\n"
2280    "       [,zlib-glz-wan-compression=[auto|never|always]]\n"
2281    "       [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n"
2282    "       [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n"
2283    "       [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
2284    "       [,gl=[on|off]][,rendernode=<file>]\n"
2285    "                enable spice\n"
2286    "                at least one of {port, tls-port} is mandatory\n",
2287    QEMU_ARCH_ALL)
2288#endif
2289SRST
2290``-spice option[,option[,...]]``
2291    Enable the spice remote desktop protocol. Valid options are
2292
2293    ``port=<nr>``
2294        Set the TCP port spice is listening on for plaintext channels.
2295
2296    ``addr=<addr>``
2297        Set the IP address spice is listening on. Default is any
2298        address.
2299
2300    ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off``
2301        Force using the specified IP version.
2302
2303    ``password-secret=<secret-id>``
2304        Set the ID of the ``secret`` object containing the password
2305        you need to authenticate.
2306
2307    ``sasl=on|off``
2308        Require that the client use SASL to authenticate with the spice.
2309        The exact choice of authentication method used is controlled
2310        from the system / user's SASL configuration file for the 'qemu'
2311        service. This is typically found in /etc/sasl2/qemu.conf. If
2312        running QEMU as an unprivileged user, an environment variable
2313        SASL\_CONF\_PATH can be used to make it search alternate
2314        locations for the service config. While some SASL auth methods
2315        can also provide data encryption (eg GSSAPI), it is recommended
2316        that SASL always be combined with the 'tls' and 'x509' settings
2317        to enable use of SSL and server certificates. This ensures a
2318        data encryption preventing compromise of authentication
2319        credentials.
2320
2321    ``disable-ticketing=on|off``
2322        Allow client connects without authentication.
2323
2324    ``disable-copy-paste=on|off``
2325        Disable copy paste between the client and the guest.
2326
2327    ``disable-agent-file-xfer=on|off``
2328        Disable spice-vdagent based file-xfer between the client and the
2329        guest.
2330
2331    ``tls-port=<nr>``
2332        Set the TCP port spice is listening on for encrypted channels.
2333
2334    ``x509-dir=<dir>``
2335        Set the x509 file directory. Expects same filenames as -vnc
2336        $display,x509=$dir
2337
2338    ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>``
2339        The x509 file names can also be configured individually.
2340
2341    ``tls-ciphers=<list>``
2342        Specify which ciphers to use.
2343
2344    ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]``
2345        Force specific channel to be used with or without TLS
2346        encryption. The options can be specified multiple times to
2347        configure multiple channels. The special name "default" can be
2348        used to set the default mode. For channels which are not
2349        explicitly forced into one mode the spice client is allowed to
2350        pick tls/plaintext as he pleases.
2351
2352    ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]``
2353        Configure image compression (lossless). Default is auto\_glz.
2354
2355    ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]``
2356        Configure wan image compression (lossy for slow links). Default
2357        is auto.
2358
2359    ``streaming-video=[off|all|filter]``
2360        Configure video stream detection. Default is off.
2361
2362    ``agent-mouse=[on|off]``
2363        Enable/disable passing mouse events via vdagent. Default is on.
2364
2365    ``playback-compression=[on|off]``
2366        Enable/disable audio stream compression (using celt 0.5.1).
2367        Default is on.
2368
2369    ``seamless-migration=[on|off]``
2370        Enable/disable spice seamless migration. Default is off.
2371
2372    ``gl=[on|off]``
2373        Enable/disable OpenGL context. Default is off.
2374
2375    ``rendernode=<file>``
2376        DRM render node for OpenGL rendering. If not specified, it will
2377        pick the first available. (Since 2.9)
2378ERST
2379
2380DEF("portrait", 0, QEMU_OPTION_portrait,
2381    "-portrait       rotate graphical output 90 deg left (only PXA LCD)\n",
2382    QEMU_ARCH_ALL)
2383SRST
2384``-portrait``
2385    Rotate graphical output 90 deg left (only PXA LCD).
2386ERST
2387
2388DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
2389    "-rotate <deg>   rotate graphical output some deg left (only PXA LCD)\n",
2390    QEMU_ARCH_ALL)
2391SRST
2392``-rotate deg``
2393    Rotate graphical output some deg left (only PXA LCD).
2394ERST
2395
2396DEF("vga", HAS_ARG, QEMU_OPTION_vga,
2397    "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
2398    "                select video card type\n", QEMU_ARCH_ALL)
2399SRST
2400``-vga type``
2401    Select type of VGA card to emulate. Valid values for type are
2402
2403    ``cirrus``
2404        Cirrus Logic GD5446 Video card. All Windows versions starting
2405        from Windows 95 should recognize and use this graphic card. For
2406        optimal performances, use 16 bit color depth in the guest and
2407        the host OS. (This card was the default before QEMU 2.2)
2408
2409    ``std``
2410        Standard VGA card with Bochs VBE extensions. If your guest OS
2411        supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
2412        you want to use high resolution modes (>= 1280x1024x16) then you
2413        should use this option. (This card is the default since QEMU
2414        2.2)
2415
2416    ``vmware``
2417        VMWare SVGA-II compatible adapter. Use it if you have
2418        sufficiently recent XFree86/XOrg server or Windows guest with a
2419        driver for this card.
2420
2421    ``qxl``
2422        QXL paravirtual graphic card. It is VGA compatible (including
2423        VESA 2.0 VBE support). Works best with qxl guest drivers
2424        installed though. Recommended choice when using the spice
2425        protocol.
2426
2427    ``tcx``
2428        (sun4m only) Sun TCX framebuffer. This is the default
2429        framebuffer for sun4m machines and offers both 8-bit and 24-bit
2430        colour depths at a fixed resolution of 1024x768.
2431
2432    ``cg3``
2433        (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit
2434        framebuffer for sun4m machines available in both 1024x768
2435        (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people
2436        wishing to run older Solaris versions.
2437
2438    ``virtio``
2439        Virtio VGA card.
2440
2441    ``none``
2442        Disable VGA card.
2443ERST
2444
2445DEF("full-screen", 0, QEMU_OPTION_full_screen,
2446    "-full-screen    start in full screen\n", QEMU_ARCH_ALL)
2447SRST
2448``-full-screen``
2449    Start in full screen.
2450ERST
2451
2452DEF("g", HAS_ARG, QEMU_OPTION_g ,
2453    "-g WxH[xDEPTH]  Set the initial graphical resolution and depth\n",
2454    QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K)
2455SRST
2456``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]``
2457    Set the initial graphical resolution and depth (PPC, SPARC only).
2458
2459    For PPC the default is 800x600x32.
2460
2461    For SPARC with the TCX graphics device, the default is 1024x768x8
2462    with the option of 1024x768x24. For cgthree, the default is
2463    1024x768x8 with the option of 1152x900x8 for people who wish to use
2464    OBP.
2465ERST
2466
2467#ifdef CONFIG_VNC
2468DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
2469    "-vnc <display>  shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
2470#endif
2471SRST
2472``-vnc display[,option[,option[,...]]]``
2473    Normally, if QEMU is compiled with graphical window support, it
2474    displays output such as guest graphics, guest console, and the QEMU
2475    monitor in a window. With this option, you can have QEMU listen on
2476    VNC display display and redirect the VGA display over the VNC
2477    session. It is very useful to enable the usb tablet device when
2478    using this option (option ``-device usb-tablet``). When using the
2479    VNC display, you must use the ``-k`` parameter to set the keyboard
2480    layout if you are not using en-us. Valid syntax for the display is
2481
2482    ``to=L``
2483        With this option, QEMU will try next available VNC displays,
2484        until the number L, if the originally defined "-vnc display" is
2485        not available, e.g. port 5900+display is already used by another
2486        application. By default, to=0.
2487
2488    ``host:d``
2489        TCP connections will only be allowed from host on display d. By
2490        convention the TCP port is 5900+d. Optionally, host can be
2491        omitted in which case the server will accept connections from
2492        any host.
2493
2494    ``unix:path``
2495        Connections will be allowed over UNIX domain sockets where path
2496        is the location of a unix socket to listen for connections on.
2497
2498    ``none``
2499        VNC is initialized but not started. The monitor ``change``
2500        command can be used to later start the VNC server.
2501
2502    Following the display value there may be one or more option flags
2503    separated by commas. Valid options are
2504
2505    ``reverse=on|off``
2506        Connect to a listening VNC client via a "reverse" connection.
2507        The client is specified by the display. For reverse network
2508        connections (host:d,``reverse``), the d argument is a TCP port
2509        number, not a display number.
2510
2511    ``websocket=on|off``
2512        Opens an additional TCP listening port dedicated to VNC
2513        Websocket connections. If a bare websocket option is given, the
2514        Websocket port is 5700+display. An alternative port can be
2515        specified with the syntax ``websocket``\ =port.
2516
2517        If host is specified connections will only be allowed from this
2518        host. It is possible to control the websocket listen address
2519        independently, using the syntax ``websocket``\ =host:port.
2520
2521        Websocket could be allowed over UNIX domain socket, using the syntax
2522        ``websocket``\ =unix:path, where path is the location of a unix socket
2523        to listen for connections on.
2524
2525        If no TLS credentials are provided, the websocket connection
2526        runs in unencrypted mode. If TLS credentials are provided, the
2527        websocket connection requires encrypted client connections.
2528
2529    ``password=on|off``
2530        Require that password based authentication is used for client
2531        connections.
2532
2533        The password must be set separately using the ``set_password``
2534        command in the :ref:`QEMU monitor`. The
2535        syntax to change your password is:
2536        ``set_password <protocol> <password>`` where <protocol> could be
2537        either "vnc" or "spice".
2538
2539        If you would like to change <protocol> password expiration, you
2540        should use ``expire_password <protocol> <expiration-time>``
2541        where expiration time could be one of the following options:
2542        now, never, +seconds or UNIX time of expiration, e.g. +60 to
2543        make password expire in 60 seconds, or 1335196800 to make
2544        password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for
2545        this date and time).
2546
2547        You can also use keywords "now" or "never" for the expiration
2548        time to allow <protocol> password to expire immediately or never
2549        expire.
2550
2551    ``password-secret=<secret-id>``
2552        Require that password based authentication is used for client
2553        connections, using the password provided by the ``secret``
2554        object identified by ``secret-id``.
2555
2556    ``tls-creds=ID``
2557        Provides the ID of a set of TLS credentials to use to secure the
2558        VNC server. They will apply to both the normal VNC server socket
2559        and the websocket socket (if enabled). Setting TLS credentials
2560        will cause the VNC server socket to enable the VeNCrypt auth
2561        mechanism. The credentials should have been previously created
2562        using the ``-object tls-creds`` argument.
2563
2564    ``tls-authz=ID``
2565        Provides the ID of the QAuthZ authorization object against which
2566        the client's x509 distinguished name will validated. This object
2567        is only resolved at time of use, so can be deleted and recreated
2568        on the fly while the VNC server is active. If missing, it will
2569        default to denying access.
2570
2571    ``sasl=on|off``
2572        Require that the client use SASL to authenticate with the VNC
2573        server. The exact choice of authentication method used is
2574        controlled from the system / user's SASL configuration file for
2575        the 'qemu' service. This is typically found in
2576        /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
2577        an environment variable SASL\_CONF\_PATH can be used to make it
2578        search alternate locations for the service config. While some
2579        SASL auth methods can also provide data encryption (eg GSSAPI),
2580        it is recommended that SASL always be combined with the 'tls'
2581        and 'x509' settings to enable use of SSL and server
2582        certificates. This ensures a data encryption preventing
2583        compromise of authentication credentials. See the
2584        :ref:`VNC security` section in the System Emulation Users Guide
2585        for details on using SASL authentication.
2586
2587    ``sasl-authz=ID``
2588        Provides the ID of the QAuthZ authorization object against which
2589        the client's SASL username will validated. This object is only
2590        resolved at time of use, so can be deleted and recreated on the
2591        fly while the VNC server is active. If missing, it will default
2592        to denying access.
2593
2594    ``acl=on|off``
2595        Legacy method for enabling authorization of clients against the
2596        x509 distinguished name and SASL username. It results in the
2597        creation of two ``authz-list`` objects with IDs of
2598        ``vnc.username`` and ``vnc.x509dname``. The rules for these
2599        objects must be configured with the HMP ACL commands.
2600
2601        This option is deprecated and should no longer be used. The new
2602        ``sasl-authz`` and ``tls-authz`` options are a replacement.
2603
2604    ``lossy=on|off``
2605        Enable lossy compression methods (gradient, JPEG, ...). If this
2606        option is set, VNC client may receive lossy framebuffer updates
2607        depending on its encoding settings. Enabling this option can
2608        save a lot of bandwidth at the expense of quality.
2609
2610    ``non-adaptive=on|off``
2611        Disable adaptive encodings. Adaptive encodings are enabled by
2612        default. An adaptive encoding will try to detect frequently
2613        updated screen regions, and send updates in these regions using
2614        a lossy encoding (like JPEG). This can be really helpful to save
2615        bandwidth when playing videos. Disabling adaptive encodings
2616        restores the original static behavior of encodings like Tight.
2617
2618    ``share=[allow-exclusive|force-shared|ignore]``
2619        Set display sharing policy. 'allow-exclusive' allows clients to
2620        ask for exclusive access. As suggested by the rfb spec this is
2621        implemented by dropping other connections. Connecting multiple
2622        clients in parallel requires all clients asking for a shared
2623        session (vncviewer: -shared switch). This is the default.
2624        'force-shared' disables exclusive client access. Useful for
2625        shared desktop sessions, where you don't want someone forgetting
2626        specify -shared disconnect everybody else. 'ignore' completely
2627        ignores the shared flag and allows everybody connect
2628        unconditionally. Doesn't conform to the rfb spec but is
2629        traditional QEMU behavior.
2630
2631    ``key-delay-ms``
2632        Set keyboard delay, for key down and key up events, in
2633        milliseconds. Default is 10. Keyboards are low-bandwidth
2634        devices, so this slowdown can help the device and guest to keep
2635        up and not lose events in case events are arriving in bulk.
2636        Possible causes for the latter are flaky network connections, or
2637        scripts for automated testing.
2638
2639    ``audiodev=audiodev``
2640        Use the specified audiodev when the VNC client requests audio
2641        transmission. When not using an -audiodev argument, this option
2642        must be omitted, otherwise is must be present and specify a
2643        valid audiodev.
2644
2645    ``power-control=on|off``
2646        Permit the remote client to issue shutdown, reboot or reset power
2647        control requests.
2648ERST
2649
2650ARCHHEADING(, QEMU_ARCH_I386)
2651
2652ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2653
2654DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2655    "-win2k-hack     use it when installing Windows 2000 to avoid a disk full bug\n",
2656    QEMU_ARCH_I386)
2657SRST
2658``-win2k-hack``
2659    Use it when installing Windows 2000 to avoid a disk full bug. After
2660    Windows 2000 is installed, you no longer need this option (this
2661    option slows down the IDE transfers).  Synonym of ``-global
2662    ide-device.win2k-install-hack=on``.
2663ERST
2664
2665DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2666    "-no-fd-bootchk  disable boot signature checking for floppy disks\n",
2667    QEMU_ARCH_I386)
2668SRST
2669``-no-fd-bootchk``
2670    Disable boot signature checking for floppy disks in BIOS. May be
2671    needed to boot from old floppy disks.  Synonym of ``-m fd-bootchk=off``.
2672ERST
2673
2674DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2675    "-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"
2676    "                ACPI table description\n", QEMU_ARCH_I386)
2677SRST
2678``-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]...]``
2679    Add ACPI table with specified header fields and context from
2680    specified files. For file=, take whole ACPI table from the specified
2681    files, including all ACPI headers (possible overridden by other
2682    options). For data=, only data portion of the table is used, all
2683    header information is specified in the command line. If a SLIC table
2684    is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
2685    fields will override the same in the RSDT and the FADT (a.k.a.
2686    FACP), in order to ensure the field matches required by the
2687    Microsoft SLIC spec and the ACPI spec.
2688ERST
2689
2690DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2691    "-smbios file=binary\n"
2692    "                load SMBIOS entry from binary file\n"
2693    "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2694    "              [,uefi=on|off]\n"
2695    "                specify SMBIOS type 0 fields\n"
2696    "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2697    "              [,uuid=uuid][,sku=str][,family=str]\n"
2698    "                specify SMBIOS type 1 fields\n"
2699    "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2700    "              [,asset=str][,location=str]\n"
2701    "                specify SMBIOS type 2 fields\n"
2702    "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2703    "              [,sku=str]\n"
2704    "                specify SMBIOS type 3 fields\n"
2705    "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2706    "              [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
2707    "              [,processor-family=%d][,processor-id=%d]\n"
2708    "                specify SMBIOS type 4 fields\n"
2709    "-smbios type=8[,external_reference=str][,internal_reference=str][,connector_type=%d][,port_type=%d]\n"
2710    "                specify SMBIOS type 8 fields\n"
2711    "-smbios type=11[,value=str][,path=filename]\n"
2712    "                specify SMBIOS type 11 fields\n"
2713    "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2714    "               [,asset=str][,part=str][,speed=%d]\n"
2715    "                specify SMBIOS type 17 fields\n"
2716    "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n"
2717    "                specify SMBIOS type 41 fields\n",
2718    QEMU_ARCH_I386 | QEMU_ARCH_ARM | QEMU_ARCH_LOONGARCH | QEMU_ARCH_RISCV)
2719SRST
2720``-smbios file=binary``
2721    Load SMBIOS entry from binary file.
2722
2723``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]``
2724    Specify SMBIOS type 0 fields
2725
2726``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]``
2727    Specify SMBIOS type 1 fields
2728
2729``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]``
2730    Specify SMBIOS type 2 fields
2731
2732``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
2733    Specify SMBIOS type 3 fields
2734
2735``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str][,processor-family=%d][,processor-id=%d]``
2736    Specify SMBIOS type 4 fields
2737
2738``-smbios type=9[,slot_designation=str][,slot_type=%d][,slot_data_bus_width=%d][,current_usage=%d][,slot_length=%d][,slot_id=%d][,slot_characteristics1=%d][,slot_characteristics12=%d][,pci_device=str]``
2739    Specify SMBIOS type 9 fields
2740
2741``-smbios type=11[,value=str][,path=filename]``
2742    Specify SMBIOS type 11 fields
2743
2744    This argument can be repeated multiple times, and values are added in the order they are parsed.
2745    Applications intending to use OEM strings data are encouraged to use their application name as
2746    a prefix for the value string. This facilitates passing information for multiple applications
2747    concurrently.
2748
2749    The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax
2750    loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes.
2751
2752    Both the ``value`` and ``path`` options can be repeated multiple times and will be added to
2753    the SMBIOS table in the order in which they appear.
2754
2755    Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535
2756    bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the
2757    guest. Instead it should be used as a indicator to inform the guest where to locate the real
2758    data set, for example, by specifying the serial ID of a block device.
2759
2760    An example passing three strings is
2761
2762    .. parsed-literal::
2763
2764        -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\
2765                        value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\
2766                        path=/some/file/with/oemstringsdata.txt
2767
2768    In the guest OS this is visible with the ``dmidecode`` command
2769
2770     .. parsed-literal::
2771
2772         $ dmidecode -t 11
2773         Handle 0x0E00, DMI type 11, 5 bytes
2774         OEM Strings
2775              String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/
2776              String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os
2777              String 3: myapp:some extra data
2778
2779
2780``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]``
2781    Specify SMBIOS type 17 fields
2782
2783``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]``
2784    Specify SMBIOS type 41 fields
2785
2786    This argument can be repeated multiple times.  Its main use is to allow network interfaces be created
2787    as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface
2788    position on the PCI bus.
2789
2790    Here is an example of use:
2791
2792    .. parsed-literal::
2793
2794        -netdev user,id=internet \\
2795        -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\
2796        -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev
2797
2798    In the guest OS, the device should then appear as ``eno1``:
2799
2800    ..parsed-literal::
2801
2802         $ ip -brief l
2803         lo               UNKNOWN        00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
2804         eno1             UP             50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP>
2805
2806    Currently, the PCI device has to be attached to the root bus.
2807
2808ERST
2809
2810DEFHEADING()
2811
2812DEFHEADING(Network options:)
2813
2814DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2815#ifdef CONFIG_SLIRP
2816    "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n"
2817    "         [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2818    "         [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2819    "         [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2820    "         [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2821#ifndef _WIN32
2822                                             "[,smb=dir[,smbserver=addr]]\n"
2823#endif
2824    "                configure a user mode network backend with ID 'str',\n"
2825    "                its DHCP server and optional services\n"
2826#endif
2827#ifdef _WIN32
2828    "-netdev tap,id=str,ifname=name\n"
2829    "                configure a host TAP network backend with ID 'str'\n"
2830#else
2831    "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2832    "         [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2833    "         [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2834    "         [,poll-us=n]\n"
2835    "                configure a host TAP network backend with ID 'str'\n"
2836    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2837    "                use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2838    "                to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2839    "                to deconfigure it\n"
2840    "                use '[down]script=no' to disable script execution\n"
2841    "                use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2842    "                configure it\n"
2843    "                use 'fd=h' to connect to an already opened TAP interface\n"
2844    "                use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2845    "                use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2846    "                default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2847    "                use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2848    "                use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2849    "                use vhost=on to enable experimental in kernel accelerator\n"
2850    "                    (only has effect for virtio guests which use MSIX)\n"
2851    "                use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2852    "                use 'vhostfd=h' to connect to an already opened vhost net device\n"
2853    "                use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2854    "                use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2855    "                use 'poll-us=n' to specify the maximum number of microseconds that could be\n"
2856    "                spent on busy polling for vhost net\n"
2857    "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2858    "                configure a host TAP network backend with ID 'str' that is\n"
2859    "                connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2860    "                using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2861#endif
2862#ifdef __linux__
2863    "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2864    "         [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n"
2865    "         [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n"
2866    "         [,rxcookie=rxcookie][,offset=offset]\n"
2867    "                configure a network backend with ID 'str' connected to\n"
2868    "                an Ethernet over L2TPv3 pseudowire.\n"
2869    "                Linux kernel 3.3+ as well as most routers can talk\n"
2870    "                L2TPv3. This transport allows connecting a VM to a VM,\n"
2871    "                VM to a router and even VM to Host. It is a nearly-universal\n"
2872    "                standard (RFC3931). Note - this implementation uses static\n"
2873    "                pre-configured tunnels (same as the Linux kernel).\n"
2874    "                use 'src=' to specify source address\n"
2875    "                use 'dst=' to specify destination address\n"
2876    "                use 'udp=on' to specify udp encapsulation\n"
2877    "                use 'srcport=' to specify source udp port\n"
2878    "                use 'dstport=' to specify destination udp port\n"
2879    "                use 'ipv6=on' to force v6\n"
2880    "                L2TPv3 uses cookies to prevent misconfiguration as\n"
2881    "                well as a weak security measure\n"
2882    "                use 'rxcookie=0x012345678' to specify a rxcookie\n"
2883    "                use 'txcookie=0x012345678' to specify a txcookie\n"
2884    "                use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2885    "                use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2886    "                use 'pincounter=on' to work around broken counter handling in peer\n"
2887    "                use 'offset=X' to add an extra offset between header and data\n"
2888#endif
2889    "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2890    "                configure a network backend to connect to another network\n"
2891    "                using a socket connection\n"
2892    "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2893    "                configure a network backend to connect to a multicast maddr and port\n"
2894    "                use 'localaddr=addr' to specify the host address to send packets from\n"
2895    "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2896    "                configure a network backend to connect to another network\n"
2897    "                using an UDP tunnel\n"
2898    "-netdev stream,id=str[,server=on|off],addr.type=inet,addr.host=host,addr.port=port[,to=maxport][,numeric=on|off][,keep-alive=on|off][,mptcp=on|off][,addr.ipv4=on|off][,addr.ipv6=on|off][,reconnect=seconds]\n"
2899    "-netdev stream,id=str[,server=on|off],addr.type=unix,addr.path=path[,abstract=on|off][,tight=on|off][,reconnect=seconds]\n"
2900    "-netdev stream,id=str[,server=on|off],addr.type=fd,addr.str=file-descriptor[,reconnect=seconds]\n"
2901    "                configure a network backend to connect to another network\n"
2902    "                using a socket connection in stream mode.\n"
2903    "-netdev dgram,id=str,remote.type=inet,remote.host=maddr,remote.port=port[,local.type=inet,local.host=addr]\n"
2904    "-netdev dgram,id=str,remote.type=inet,remote.host=maddr,remote.port=port[,local.type=fd,local.str=file-descriptor]\n"
2905    "                configure a network backend to connect to a multicast maddr and port\n"
2906    "                use ``local.host=addr`` to specify the host address to send packets from\n"
2907    "-netdev dgram,id=str,local.type=inet,local.host=addr,local.port=port[,remote.type=inet,remote.host=addr,remote.port=port]\n"
2908    "-netdev dgram,id=str,local.type=unix,local.path=path[,remote.type=unix,remote.path=path]\n"
2909    "-netdev dgram,id=str,local.type=fd,local.str=file-descriptor\n"
2910    "                configure a network backend to connect to another network\n"
2911    "                using an UDP tunnel\n"
2912#ifdef CONFIG_VDE
2913    "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2914    "                configure a network backend to connect to port 'n' of a vde switch\n"
2915    "                running on host and listening for incoming connections on 'socketpath'.\n"
2916    "                Use group 'groupname' and mode 'octalmode' to change default\n"
2917    "                ownership and permissions for communication port.\n"
2918#endif
2919#ifdef CONFIG_NETMAP
2920    "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2921    "                attach to the existing netmap-enabled network interface 'name', or to a\n"
2922    "                VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2923    "                netmap device, defaults to '/dev/netmap')\n"
2924#endif
2925#ifdef CONFIG_AF_XDP
2926    "-netdev af-xdp,id=str,ifname=name[,mode=native|skb][,force-copy=on|off]\n"
2927    "         [,queues=n][,start-queue=m][,inhibit=on|off][,sock-fds=x:y:...:z]\n"
2928    "                attach to the existing network interface 'name' with AF_XDP socket\n"
2929    "                use 'mode=MODE' to specify an XDP program attach mode\n"
2930    "                use 'force-copy=on|off' to force XDP copy mode even if device supports zero-copy (default: off)\n"
2931    "                use 'inhibit=on|off' to inhibit loading of a default XDP program (default: off)\n"
2932    "                with inhibit=on,\n"
2933    "                  use 'sock-fds' to provide file descriptors for already open AF_XDP sockets\n"
2934    "                  added to a socket map in XDP program.  One socket per queue.\n"
2935    "                use 'queues=n' to specify how many queues of a multiqueue interface should be used\n"
2936    "                use 'start-queue=m' to specify the first queue that should be used\n"
2937#endif
2938#ifdef CONFIG_POSIX
2939    "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2940    "                configure a vhost-user network, backed by a chardev 'dev'\n"
2941#endif
2942#ifdef __linux__
2943    "-netdev vhost-vdpa,id=str[,vhostdev=/path/to/dev][,vhostfd=h]\n"
2944    "                configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n"
2945    "                use 'vhostdev=/path/to/dev' to open a vhost vdpa device\n"
2946    "                use 'vhostfd=h' to connect to an already opened vhost vdpa device\n"
2947#endif
2948#ifdef CONFIG_VMNET
2949    "-netdev vmnet-host,id=str[,isolated=on|off][,net-uuid=uuid]\n"
2950    "         [,start-address=addr,end-address=addr,subnet-mask=mask]\n"
2951    "                configure a vmnet network backend in host mode with ID 'str',\n"
2952    "                isolate this interface from others with 'isolated',\n"
2953    "                configure the address range and choose a subnet mask,\n"
2954    "                specify network UUID 'uuid' to disable DHCP and interact with\n"
2955    "                vmnet-host interfaces within this isolated network\n"
2956    "-netdev vmnet-shared,id=str[,isolated=on|off][,nat66-prefix=addr]\n"
2957    "         [,start-address=addr,end-address=addr,subnet-mask=mask]\n"
2958    "                configure a vmnet network backend in shared mode with ID 'str',\n"
2959    "                configure the address range and choose a subnet mask,\n"
2960    "                set IPv6 ULA prefix (of length 64) to use for internal network,\n"
2961    "                isolate this interface from others with 'isolated'\n"
2962    "-netdev vmnet-bridged,id=str,ifname=name[,isolated=on|off]\n"
2963    "                configure a vmnet network backend in bridged mode with ID 'str',\n"
2964    "                use 'ifname=name' to select a physical network interface to be bridged,\n"
2965    "                isolate this interface from others with 'isolated'\n"
2966#endif
2967    "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2968    "                configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2969DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2970    "-nic [tap|bridge|"
2971#ifdef CONFIG_SLIRP
2972    "user|"
2973#endif
2974#ifdef __linux__
2975    "l2tpv3|"
2976#endif
2977#ifdef CONFIG_VDE
2978    "vde|"
2979#endif
2980#ifdef CONFIG_NETMAP
2981    "netmap|"
2982#endif
2983#ifdef CONFIG_AF_XDP
2984    "af-xdp|"
2985#endif
2986#ifdef CONFIG_POSIX
2987    "vhost-user|"
2988#endif
2989#ifdef CONFIG_VMNET
2990    "vmnet-host|vmnet-shared|vmnet-bridged|"
2991#endif
2992    "socket][,option][,...][mac=macaddr]\n"
2993    "                initialize an on-board / default host NIC (using MAC address\n"
2994    "                macaddr) and connect it to the given host network backend\n"
2995    "-nic none       use it alone to have zero network devices (the default is to\n"
2996    "                provided a 'user' network connection)\n",
2997    QEMU_ARCH_ALL)
2998DEF("net", HAS_ARG, QEMU_OPTION_net,
2999    "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
3000    "                configure or create an on-board (or machine default) NIC and\n"
3001    "                connect it to hub 0 (please use -nic unless you need a hub)\n"
3002    "-net ["
3003#ifdef CONFIG_SLIRP
3004    "user|"
3005#endif
3006    "tap|"
3007    "bridge|"
3008#ifdef CONFIG_VDE
3009    "vde|"
3010#endif
3011#ifdef CONFIG_NETMAP
3012    "netmap|"
3013#endif
3014#ifdef CONFIG_AF_XDP
3015    "af-xdp|"
3016#endif
3017#ifdef CONFIG_VMNET
3018    "vmnet-host|vmnet-shared|vmnet-bridged|"
3019#endif
3020    "socket][,option][,option][,...]\n"
3021    "                old way to initialize a host network interface\n"
3022    "                (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
3023SRST
3024``-nic [tap|bridge|user|l2tpv3|vde|netmap|af-xdp|vhost-user|socket][,...][,mac=macaddr][,model=mn]``
3025    This option is a shortcut for configuring both the on-board
3026    (default) guest NIC hardware and the host network backend in one go.
3027    The host backend options are the same as with the corresponding
3028    ``-netdev`` options below. The guest NIC model can be set with
3029    ``model=modelname``. Use ``model=help`` to list the available device
3030    types. The hardware MAC address can be set with ``mac=macaddr``.
3031
3032    The following two example do exactly the same, to show how ``-nic``
3033    can be used to shorten the command line length:
3034
3035    .. parsed-literal::
3036
3037        |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
3038        |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
3039
3040``-nic none``
3041    Indicate that no network devices should be configured. It is used to
3042    override the default configuration (default NIC with "user" host
3043    network backend) which is activated if no other networking options
3044    are provided.
3045
3046``-netdev user,id=id[,option][,option][,...]``
3047    Configure user mode host network backend which requires no
3048    administrator privilege to run. Valid options are:
3049
3050    ``id=id``
3051        Assign symbolic name for use in monitor commands.
3052
3053    ``ipv4=on|off and ipv6=on|off``
3054        Specify that either IPv4 or IPv6 must be enabled. If neither is
3055        specified both protocols are enabled.
3056
3057    ``net=addr[/mask]``
3058        Set IP network address the guest will see. Optionally specify
3059        the netmask, either in the form a.b.c.d or as number of valid
3060        top-most bits. Default is 10.0.2.0/24.
3061
3062    ``host=addr``
3063        Specify the guest-visible address of the host. Default is the
3064        2nd IP in the guest network, i.e. x.x.x.2.
3065
3066    ``ipv6-net=addr[/int]``
3067        Set IPv6 network address the guest will see (default is
3068        fec0::/64). The network prefix is given in the usual hexadecimal
3069        IPv6 address notation. The prefix size is optional, and is given
3070        as the number of valid top-most bits (default is 64).
3071
3072    ``ipv6-host=addr``
3073        Specify the guest-visible IPv6 address of the host. Default is
3074        the 2nd IPv6 in the guest network, i.e. xxxx::2.
3075
3076    ``restrict=on|off``
3077        If this option is enabled, the guest will be isolated, i.e. it
3078        will not be able to contact the host and no guest IP packets
3079        will be routed over the host to the outside. This option does
3080        not affect any explicitly set forwarding rules.
3081
3082    ``hostname=name``
3083        Specifies the client hostname reported by the built-in DHCP
3084        server.
3085
3086    ``dhcpstart=addr``
3087        Specify the first of the 16 IPs the built-in DHCP server can
3088        assign. Default is the 15th to 31st IP in the guest network,
3089        i.e. x.x.x.15 to x.x.x.31.
3090
3091    ``dns=addr``
3092        Specify the guest-visible address of the virtual nameserver. The
3093        address must be different from the host address. Default is the
3094        3rd IP in the guest network, i.e. x.x.x.3.
3095
3096    ``ipv6-dns=addr``
3097        Specify the guest-visible address of the IPv6 virtual
3098        nameserver. The address must be different from the host address.
3099        Default is the 3rd IP in the guest network, i.e. xxxx::3.
3100
3101    ``dnssearch=domain``
3102        Provides an entry for the domain-search list sent by the
3103        built-in DHCP server. More than one domain suffix can be
3104        transmitted by specifying this option multiple times. If
3105        supported, this will cause the guest to automatically try to
3106        append the given domain suffix(es) in case a domain name can not
3107        be resolved.
3108
3109        Example:
3110
3111        .. parsed-literal::
3112
3113            |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
3114
3115    ``domainname=domain``
3116        Specifies the client domain name reported by the built-in DHCP
3117        server.
3118
3119    ``tftp=dir``
3120        When using the user mode network stack, activate a built-in TFTP
3121        server. The files in dir will be exposed as the root of a TFTP
3122        server. The TFTP client on the guest must be configured in
3123        binary mode (use the command ``bin`` of the Unix TFTP client).
3124        The built-in TFTP server is read-only; it does not implement any
3125        command for writing files. QEMU will not write to this directory.
3126
3127    ``tftp-server-name=name``
3128        In BOOTP reply, broadcast name as the "TFTP server name"
3129        (RFC2132 option 66). This can be used to advise the guest to
3130        load boot files or configurations from a different server than
3131        the host address.
3132
3133    ``bootfile=file``
3134        When using the user mode network stack, broadcast file as the
3135        BOOTP filename. In conjunction with ``tftp``, this can be used
3136        to network boot a guest from a local directory.
3137
3138        Example (using pxelinux):
3139
3140        .. parsed-literal::
3141
3142            |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\
3143                -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
3144
3145    ``smb=dir[,smbserver=addr]``
3146        When using the user mode network stack, activate a built-in SMB
3147        server so that Windows OSes can access to the host files in
3148        ``dir`` transparently. The IP address of the SMB server can be
3149        set to addr. By default the 4th IP in the guest network is used,
3150        i.e. x.x.x.4.
3151
3152        In the guest Windows OS, the line:
3153
3154        ::
3155
3156            10.0.2.4 smbserver
3157
3158        must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows
3159        9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows
3160        NT/2000).
3161
3162        Then ``dir`` can be accessed in ``\\smbserver\qemu``.
3163
3164        Note that a SAMBA server must be installed on the host OS.
3165
3166    ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
3167        Redirect incoming TCP or UDP connections to the host port
3168        hostport to the guest IP address guestaddr on guest port
3169        guestport. If guestaddr is not specified, its value is x.x.x.15
3170        (default first address given by the built-in DHCP server). By
3171        specifying hostaddr, the rule can be bound to a specific host
3172        interface. If no connection type is set, TCP is used. This
3173        option can be given multiple times.
3174
3175        For example, to redirect host X11 connection from screen 1 to
3176        guest screen 0, use the following:
3177
3178        .. parsed-literal::
3179
3180            # on the host
3181            |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
3182            # this host xterm should open in the guest X11 server
3183            xterm -display :1
3184
3185        To redirect telnet connections from host port 5555 to telnet
3186        port on the guest, use the following:
3187
3188        .. parsed-literal::
3189
3190            # on the host
3191            |qemu_system| -nic user,hostfwd=tcp::5555-:23
3192            telnet localhost 5555
3193
3194        Then when you use on the host ``telnet localhost 5555``, you
3195        connect to the guest telnet server.
3196
3197    ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command``
3198        Forward guest TCP connections to the IP address server on port
3199        port to the character device dev or to a program executed by
3200        cmd:command which gets spawned for each connection. This option
3201        can be given multiple times.
3202
3203        You can either use a chardev directly and have that one used
3204        throughout QEMU's lifetime, like in the following example:
3205
3206        .. parsed-literal::
3207
3208            # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
3209            # the guest accesses it
3210            |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
3211
3212        Or you can execute a command on every TCP connection established
3213        by the guest, so that QEMU behaves similar to an inetd process
3214        for that virtual server:
3215
3216        .. parsed-literal::
3217
3218            # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
3219            # and connect the TCP stream to its stdin/stdout
3220            |qemu_system| -nic  'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
3221
3222``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
3223    Configure a host TAP network backend with ID id.
3224
3225    Use the network script file to configure it and the network script
3226    dfile to deconfigure it. If name is not provided, the OS
3227    automatically provides one. The default network configure script is
3228    ``/etc/qemu-ifup`` and the default network deconfigure script is
3229    ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
3230    disable script execution.
3231
3232    If running QEMU as an unprivileged user, use the network helper
3233    to configure the TAP interface and attach it to the bridge.
3234    The default network helper executable is
3235    ``/path/to/qemu-bridge-helper`` and the default bridge device is
3236    ``br0``.
3237
3238    ``fd``\ =h can be used to specify the handle of an already opened
3239    host TAP interface.
3240
3241    Examples:
3242
3243    .. parsed-literal::
3244
3245        #launch a QEMU instance with the default network script
3246        |qemu_system| linux.img -nic tap
3247
3248    .. parsed-literal::
3249
3250        #launch a QEMU instance with two NICs, each one connected
3251        #to a TAP device
3252        |qemu_system| linux.img \\
3253                -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\
3254                -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
3255
3256    .. parsed-literal::
3257
3258        #launch a QEMU instance with the default network helper to
3259        #connect a TAP device to bridge br0
3260        |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3261                -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
3262
3263``-netdev bridge,id=id[,br=bridge][,helper=helper]``
3264    Connect a host TAP network interface to a host bridge device.
3265
3266    Use the network helper helper to configure the TAP interface and
3267    attach it to the bridge. The default network helper executable is
3268    ``/path/to/qemu-bridge-helper`` and the default bridge device is
3269    ``br0``.
3270
3271    Examples:
3272
3273    .. parsed-literal::
3274
3275        #launch a QEMU instance with the default network helper to
3276        #connect a TAP device to bridge br0
3277        |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
3278
3279    .. parsed-literal::
3280
3281        #launch a QEMU instance with the default network helper to
3282        #connect a TAP device to bridge qemubr0
3283        |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
3284
3285``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
3286    This host network backend can be used to connect the guest's network
3287    to another QEMU virtual machine using a TCP socket connection. If
3288    ``listen`` is specified, QEMU waits for incoming connections on port
3289    (host is optional). ``connect`` is used to connect to another QEMU
3290    instance using the ``listen`` option. ``fd``\ =h specifies an
3291    already opened TCP socket.
3292
3293    Example:
3294
3295    .. parsed-literal::
3296
3297        # launch a first QEMU instance
3298        |qemu_system| linux.img \\
3299                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3300                         -netdev socket,id=n1,listen=:1234
3301        # connect the network of this instance to the network of the first instance
3302        |qemu_system| linux.img \\
3303                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
3304                         -netdev socket,id=n2,connect=127.0.0.1:1234
3305
3306``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]``
3307    Configure a socket host network backend to share the guest's network
3308    traffic with another QEMU virtual machines using a UDP multicast
3309    socket, effectively making a bus for every QEMU with same multicast
3310    address maddr and port. NOTES:
3311
3312    1. Several QEMU can be running on different hosts and share same bus
3313       (assuming correct multicast setup for these hosts).
3314
3315    2. mcast support is compatible with User Mode Linux (argument
3316       ``ethN=mcast``), see http://user-mode-linux.sf.net.
3317
3318    3. Use ``fd=h`` to specify an already opened UDP multicast socket.
3319
3320    Example:
3321
3322    .. parsed-literal::
3323
3324        # launch one QEMU instance
3325        |qemu_system| linux.img \\
3326                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3327                         -netdev socket,id=n1,mcast=230.0.0.1:1234
3328        # launch another QEMU instance on same "bus"
3329        |qemu_system| linux.img \\
3330                         -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
3331                         -netdev socket,id=n2,mcast=230.0.0.1:1234
3332        # launch yet another QEMU instance on same "bus"
3333        |qemu_system| linux.img \\
3334                         -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\
3335                         -netdev socket,id=n3,mcast=230.0.0.1:1234
3336
3337    Example (User Mode Linux compat.):
3338
3339    .. parsed-literal::
3340
3341        # launch QEMU instance (note mcast address selected is UML's default)
3342        |qemu_system| linux.img \\
3343                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3344                         -netdev socket,id=n1,mcast=239.192.168.1:1102
3345        # launch UML
3346        /path/to/linux ubd0=/path/to/root_fs eth0=mcast
3347
3348    Example (send packets from host's 1.2.3.4):
3349
3350    .. parsed-literal::
3351
3352        |qemu_system| linux.img \\
3353                         -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3354                         -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
3355
3356``-netdev stream,id=str[,server=on|off],addr.type=inet,addr.host=host,addr.port=port[,to=maxport][,numeric=on|off][,keep-alive=on|off][,mptcp=on|off][,addr.ipv4=on|off][,addr.ipv6=on|off][,reconnect=seconds]``
3357    Configure a network backend to connect to another QEMU virtual machine or a proxy using a TCP/IP socket.
3358
3359    ``server=on|off``
3360        if ``on`` create a server socket
3361
3362    ``addr.host=host,addr.port=port``
3363        socket address to listen on (server=on) or connect to (server=off)
3364
3365    ``to=maxport``
3366        if present, this is range of possible addresses, with port between ``port`` and ``maxport``.
3367
3368    ``numeric=on|off``
3369        if ``on`` ``host`` and ``port`` are guaranteed to be numeric, otherwise a name resolution should be attempted (default: ``off``)
3370
3371    ``keep-alive=on|off``
3372        enable keep-alive when connecting to this socket.  Not supported for passive sockets.
3373
3374    ``mptcp=on|off``
3375        enable multipath TCP
3376
3377    ``ipv4=on|off``
3378        whether to accept IPv4 addresses, default to try both IPv4 and IPv6
3379
3380    ``ipv6=on|off``
3381        whether to accept IPv6 addresses, default to try both IPv4 and IPv6
3382
3383    ``reconnect=seconds``
3384        for a client socket, if a socket is disconnected, then attempt a reconnect after the given number of seconds.
3385        Setting this to zero disables this function.  (default: 0)
3386
3387    Example (two guests connected using a TCP/IP socket):
3388
3389    .. parsed-literal::
3390
3391        # first VM
3392        |qemu_system| linux.img \\
3393                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:56 \\
3394                      -netdev stream,id=net0,server=on,addr.type=inet,addr.host=localhost,addr.port=1234
3395        # second VM
3396        |qemu_system| linux.img \\
3397                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:57 \\
3398                      -netdev stream,id=net0,server=off,addr.type=inet,addr.host=localhost,addr.port=1234,reconnect=5
3399
3400``-netdev stream,id=str[,server=on|off],addr.type=unix,addr.path=path[,abstract=on|off][,tight=on|off][,reconnect=seconds]``
3401    Configure a network backend to connect to another QEMU virtual machine or a proxy using a stream oriented unix domain socket.
3402
3403    ``server=on|off``
3404        if ``on`` create a server socket
3405
3406    ``addr.path=path``
3407        filesystem path to use
3408
3409    ``abstract=on|off``
3410        if ``on``, this is a Linux abstract socket address.
3411
3412    ``tight=on|off``
3413        if false, pad an abstract socket address with enough null bytes to make it fill struct sockaddr_un member sun_path.
3414
3415    ``reconnect=seconds``
3416        for a client socket, if a socket is disconnected, then attempt a reconnect after the given number of seconds.
3417        Setting this to zero disables this function.  (default: 0)
3418
3419    Example (using passt as a replacement of -netdev user):
3420
3421    .. parsed-literal::
3422
3423        # start passt server as a non privileged user
3424        passt
3425        UNIX domain socket bound at /tmp/passt_1.socket
3426        # start QEMU to connect to passt
3427        |qemu_system| linux.img \\
3428                      -device virtio-net,netdev=net0 \\
3429                      -netdev stream,id=net0,server=off,addr.type=unix,addr.path=/tmp/passt_1.socket
3430
3431    Example (two guests connected using a stream oriented unix domain socket):
3432
3433    .. parsed-literal::
3434
3435        # first VM
3436        |qemu_system| linux.img \\
3437                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:56 \\
3438                      netdev stream,id=net0,server=on,addr.type=unix,addr.path=/tmp/qemu0
3439        # second VM
3440        |qemu_system| linux.img \\
3441                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:57 \\
3442                      -netdev stream,id=net0,server=off,addr.type=unix,addr.path=/tmp/qemu0,reconnect=5
3443
3444``-netdev stream,id=str[,server=on|off],addr.type=fd,addr.str=file-descriptor[,reconnect=seconds]``
3445    Configure a network backend to connect to another QEMU virtual machine or a proxy using a stream oriented socket file descriptor.
3446
3447    ``server=on|off``
3448        if ``on`` create a server socket
3449
3450    ``addr.str=file-descriptor``
3451        file descriptor number to use as a socket
3452
3453    ``reconnect=seconds``
3454        for a client socket, if a socket is disconnected, then attempt a reconnect after the given number of seconds.
3455        Setting this to zero disables this function.  (default: 0)
3456
3457``-netdev dgram,id=str,remote.type=inet,remote.host=maddr,remote.port=port[,local.type=inet,local.host=addr]``
3458    Configure a network backend to connect to a multicast address.
3459
3460    ``remote.host=maddr,remote.port=port``
3461        multicast address
3462
3463    ``local.host=addr``
3464        specify the host address to send packets from
3465
3466    Example:
3467
3468    .. parsed-literal::
3469
3470        # launch one QEMU instance
3471        |qemu_system| linux.img \\
3472                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:56 \\
3473                      -netdev dgram,id=net0,remote.type=inet,remote.host=224.0.0.1,remote.port=1234
3474        # launch another QEMU instance on same "bus"
3475        |qemu_system| linux.img \\
3476                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:57 \\
3477                      -netdev dgram,id=net0,remote.type=inet,remote.host=224.0.0.1,remote.port=1234
3478        # launch yet another QEMU instance on same "bus"
3479        |qemu_system| linux.img \\
3480                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:58 \\
3481                      -netdev dgram,id=net0,remote.type=inet,remote.host=224.0.0.1,remote.port=1234
3482
3483``-netdev dgram,id=str,remote.type=inet,remote.host=maddr,remote.port=port[,local.type=fd,local.str=file-descriptor]``
3484    Configure a network backend to connect to a multicast address using a UDP socket file descriptor.
3485
3486    ``remote.host=maddr,remote.port=port``
3487        multicast address
3488
3489    ``local.str=file-descriptor``
3490        File descriptor to use to send packets
3491
3492``-netdev dgram,id=str,local.type=inet,local.host=addr,local.port=port[,remote.type=inet,remote.host=addr,remote.port=port]``
3493    Configure a network backend to connect to another QEMU virtual
3494    machine or a proxy using a datagram oriented unix domain socket.
3495
3496    ``local.host=addr,local.port=port``
3497        IP address to use to send the packets from
3498
3499    ``remote.host=addr,remote.port=port``
3500        Destination IP address
3501
3502    Example (two guests connected using an UDP/IP socket):
3503
3504    .. parsed-literal::
3505
3506        # first VM
3507        |qemu_system| linux.img \\
3508                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:56 \\
3509                      -netdev dgram,id=net0,local.type=inet,local.host=localhost,local.port=1234,remote.type=inet,remote.host=localhost,remote.port=1235
3510        # second VM
3511        |qemu_system| linux.img \\
3512                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:56 \\
3513                      -netdev dgram,id=net0,local.type=inet,local.host=localhost,local.port=1235,remote.type=inet,remote.host=localhost,remote.port=1234
3514
3515``-netdev dgram,id=str,local.type=unix,local.path=path[,remote.type=unix,remote.path=path]``
3516    Configure a network backend to connect to another QEMU virtual
3517    machine or a proxy using a datagram oriented unix socket.
3518
3519    ``local.path=path``
3520        filesystem path to use to bind the socket
3521
3522    ``remote.path=path``
3523        filesystem path to use as a destination (see sendto(2))
3524
3525    Example (two guests connected using an UDP/UNIX socket):
3526
3527    .. parsed-literal::
3528
3529        # first VM
3530        |qemu_system| linux.img \\
3531                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:56 \\
3532                      -netdev dgram,id=net0,local.type=unix,local.path=/tmp/qemu0,remote.type=unix,remote.path=/tmp/qemu1
3533        # second VM
3534        |qemu_system| linux.img \\
3535                      -device virtio-net,netdev=net0,mac=52:54:00:12:34:57 \\
3536                      -netdev dgram,id=net0,local.type=unix,local.path=/tmp/qemu1,remote.type=unix,remote.path=/tmp/qemu0
3537
3538``-netdev dgram,id=str,local.type=fd,local.str=file-descriptor``
3539    Configure a network backend to connect to another QEMU virtual
3540    machine or a proxy using a datagram oriented socket file descriptor.
3541
3542    ``local.str=file-descriptor``
3543        File descriptor to use to send packets
3544
3545``-netdev l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6=on|off][,udp=on|off][,cookie64=on|off][,counter=on|off][,pincounter=on|off][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]``
3546    Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
3547    is a popular protocol to transport Ethernet (and other Layer 2) data
3548    frames between two systems. It is present in routers, firewalls and
3549    the Linux kernel (from version 3.3 onwards).
3550
3551    This transport allows a VM to communicate to another VM, router or
3552    firewall directly.
3553
3554    ``src=srcaddr``
3555        source address (mandatory)
3556
3557    ``dst=dstaddr``
3558        destination address (mandatory)
3559
3560    ``udp=on``
3561        select udp encapsulation (default is ip).
3562
3563    ``srcport=srcport``
3564        source udp port.
3565
3566    ``dstport=dstport``
3567        destination udp port.
3568
3569    ``ipv6=on``
3570        force v6, otherwise defaults to v4.
3571
3572    ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
3573        Cookies are a weak form of security in the l2tpv3 specification.
3574        Their function is mostly to prevent misconfiguration. By default
3575        they are 32 bit.
3576
3577    ``cookie64=on``
3578        Set cookie size to 64 bit instead of the default 32
3579
3580    ``counter=off``
3581        Force a 'cut-down' L2TPv3 with no counter as in
3582        draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
3583
3584    ``pincounter=on``
3585        Work around broken counter handling in peer. This may also help
3586        on networks which have packet reorder.
3587
3588    ``offset=offset``
3589        Add an extra offset between header and data
3590
3591    For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to
3592    the bridge br-lan on the remote Linux host 1.2.3.4:
3593
3594    .. parsed-literal::
3595
3596        # Setup tunnel on linux host using raw ip as encapsulation
3597        # on 1.2.3.4
3598        ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\
3599            encap udp udp_sport 16384 udp_dport 16384
3600        ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\
3601            0xFFFFFFFF peer_session_id 0xFFFFFFFF
3602        ifconfig vmtunnel0 mtu 1500
3603        ifconfig vmtunnel0 up
3604        brctl addif br-lan vmtunnel0
3605
3606
3607        # on 4.3.2.1
3608        # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
3609
3610        |qemu_system| linux.img -device e1000,netdev=n1 \\
3611            -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp=on,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter=on
3612
3613``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
3614    Configure VDE backend to connect to PORT n of a vde switch running
3615    on host and listening for incoming connections on socketpath. Use
3616    GROUP groupname and MODE octalmode to change default ownership and
3617    permissions for communication port. This option is only available if
3618    QEMU has been compiled with vde support enabled.
3619
3620    Example:
3621
3622    .. parsed-literal::
3623
3624        # launch vde switch
3625        vde_switch -F -sock /tmp/myswitch
3626        # launch QEMU instance
3627        |qemu_system| linux.img -nic vde,sock=/tmp/myswitch
3628
3629``-netdev af-xdp,id=str,ifname=name[,mode=native|skb][,force-copy=on|off][,queues=n][,start-queue=m][,inhibit=on|off][,sock-fds=x:y:...:z]``
3630    Configure AF_XDP backend to connect to a network interface 'name'
3631    using AF_XDP socket.  A specific program attach mode for a default
3632    XDP program can be forced with 'mode', defaults to best-effort,
3633    where the likely most performant mode will be in use.  Number of queues
3634    'n' should generally match the number or queues in the interface,
3635    defaults to 1.  Traffic arriving on non-configured device queues will
3636    not be delivered to the network backend.
3637
3638    .. parsed-literal::
3639
3640        # set number of queues to 4
3641        ethtool -L eth0 combined 4
3642        # launch QEMU instance
3643        |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3644            -netdev af-xdp,id=n1,ifname=eth0,queues=4
3645
3646    'start-queue' option can be specified if a particular range of queues
3647    [m, m + n] should be in use.  For example, this is may be necessary in
3648    order to use certain NICs in native mode.  Kernel allows the driver to
3649    create a separate set of XDP queues on top of regular ones, and only
3650    these queues can be used for AF_XDP sockets.  NICs that work this way
3651    may also require an additional traffic redirection with ethtool to these
3652    special queues.
3653
3654    .. parsed-literal::
3655
3656        # set number of queues to 1
3657        ethtool -L eth0 combined 1
3658        # redirect all the traffic to the second queue (id: 1)
3659        # note: drivers may require non-empty key/mask pair.
3660        ethtool -N eth0 flow-type ether \\
3661            dst 00:00:00:00:00:00 m FF:FF:FF:FF:FF:FE action 1
3662        ethtool -N eth0 flow-type ether \\
3663            dst 00:00:00:00:00:01 m FF:FF:FF:FF:FF:FE action 1
3664        # launch QEMU instance
3665        |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3666            -netdev af-xdp,id=n1,ifname=eth0,queues=1,start-queue=1
3667
3668    XDP program can also be loaded externally.  In this case 'inhibit' option
3669    should be set to 'on' and 'sock-fds' provided with file descriptors for
3670    already open but not bound XDP sockets already added to a socket map for
3671    corresponding queues.  One socket per queue.
3672
3673    .. parsed-literal::
3674
3675        |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3676            -netdev af-xdp,id=n1,ifname=eth0,queues=3,inhibit=on,sock-fds=15:16:17
3677
3678``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
3679    Establish a vhost-user netdev, backed by a chardev id. The chardev
3680    should be a unix domain socket backed one. The vhost-user uses a
3681    specifically defined protocol to pass vhost ioctl replacement
3682    messages to an application on the other end of the socket. On
3683    non-MSIX guests, the feature can be forced with vhostforce. Use
3684    'queues=n' to specify the number of queues to be created for
3685    multiqueue vhost-user.
3686
3687    Example:
3688
3689    ::
3690
3691        qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
3692             -numa node,memdev=mem \
3693             -chardev socket,id=chr0,path=/path/to/socket \
3694             -netdev type=vhost-user,id=net0,chardev=chr0 \
3695             -device virtio-net-pci,netdev=net0
3696
3697``-netdev vhost-vdpa[,vhostdev=/path/to/dev][,vhostfd=h]``
3698    Establish a vhost-vdpa netdev.
3699
3700    vDPA device is a device that uses a datapath which complies with
3701    the virtio specifications with a vendor specific control path.
3702    vDPA devices can be both physically located on the hardware or
3703    emulated by software.
3704
3705``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
3706    Create a hub port on the emulated hub with ID hubid.
3707
3708    The hubport netdev lets you connect a NIC to a QEMU emulated hub
3709    instead of a single netdev. Alternatively, you can also connect the
3710    hubport to another netdev with ID nd by using the ``netdev=nd``
3711    option.
3712
3713``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
3714    Legacy option to configure or create an on-board (or machine
3715    default) Network Interface Card(NIC) and connect it either to the
3716    emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
3717    If model is omitted, then the default NIC model associated with the
3718    machine type is used. Note that the default NIC model may change in
3719    future QEMU releases, so it is highly recommended to always specify
3720    a model. Optionally, the MAC address can be changed to mac, the
3721    device address set to addr (PCI cards only), and a name can be
3722    assigned for use in monitor commands. Optionally, for PCI cards, you
3723    can specify the number v of MSI-X vectors that the card should have;
3724    this option currently only affects virtio cards; set v = 0 to
3725    disable MSI-X. If no ``-net`` option is specified, a single NIC is
3726    created. QEMU can emulate several different models of network card.
3727    Use ``-net nic,model=help`` for a list of available devices for your
3728    target.
3729
3730``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
3731    Configure a host network backend (with the options corresponding to
3732    the same ``-netdev`` option) and connect it to the emulated hub 0
3733    (the default hub). Use name to specify the name of the hub port.
3734ERST
3735
3736DEFHEADING()
3737
3738DEFHEADING(Character device options:)
3739
3740DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
3741    "-chardev help\n"
3742    "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3743    "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n"
3744    "         [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n"
3745    "         [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
3746    "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n"
3747    "         [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n"
3748    "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
3749    "         [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n"
3750    "         [,logfile=PATH][,logappend=on|off]\n"
3751    "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3752    "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
3753    "         [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3754    "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
3755    "-chardev file,id=id,path=path[,input-path=input-file][,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3756    "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3757#ifdef _WIN32
3758    "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3759    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3760#else
3761    "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3762    "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
3763#endif
3764#ifdef CONFIG_BRLAPI
3765    "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3766#endif
3767#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
3768        || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
3769    "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3770#endif
3771#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
3772    "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3773#endif
3774#if defined(CONFIG_SPICE)
3775    "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3776    "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3777#endif
3778    , QEMU_ARCH_ALL
3779)
3780
3781SRST
3782The general form of a character device option is:
3783
3784``-chardev backend,id=id[,mux=on|off][,options]``
3785    Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
3786    ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
3787    ``pty``, ``stdio``, ``braille``, ``parallel``,
3788    ``spicevmc``, ``spiceport``. The specific backend will determine the
3789    applicable options.
3790
3791    Use ``-chardev help`` to print all available chardev backend types.
3792
3793    All devices must have an id, which can be any string up to 127
3794    characters long. It is used to uniquely identify this device in
3795    other command line directives.
3796
3797    A character device may be used in multiplexing mode by multiple
3798    front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
3799    a "1:N" device, and here the "1" end is your specified chardev
3800    backend, and the "N" end is the various parts of QEMU that can talk
3801    to a chardev. If you create a chardev with ``id=myid`` and
3802    ``mux=on``, QEMU will create a multiplexer with your specified ID,
3803    and you can then configure multiple front ends to use that chardev
3804    ID for their input/output. Up to four different front ends can be
3805    connected to a single multiplexed chardev. (Without multiplexing
3806    enabled, a chardev can only be used by a single front end.) For
3807    instance you could use this to allow a single stdio chardev to be
3808    used by two serial ports and the QEMU monitor:
3809
3810    ::
3811
3812        -chardev stdio,mux=on,id=char0 \
3813        -mon chardev=char0,mode=readline \
3814        -serial chardev:char0 \
3815        -serial chardev:char0
3816
3817    You can have more than one multiplexer in a system configuration;
3818    for instance you could have a TCP port multiplexed between UART 0
3819    and UART 1, and stdio multiplexed between the QEMU monitor and a
3820    parallel port:
3821
3822    ::
3823
3824        -chardev stdio,mux=on,id=char0 \
3825        -mon chardev=char0,mode=readline \
3826        -parallel chardev:char0 \
3827        -chardev tcp,...,mux=on,id=char1 \
3828        -serial chardev:char1 \
3829        -serial chardev:char1
3830
3831    When you're using a multiplexed character device, some escape
3832    sequences are interpreted in the input. See the chapter about
3833    :ref:`keys in the character backend multiplexer` in the
3834    System Emulation Users Guide for more details.
3835
3836    Note that some other command line options may implicitly create
3837    multiplexed character backends; for instance ``-serial mon:stdio``
3838    creates a multiplexed stdio backend connected to the serial port and
3839    the QEMU monitor, and ``-nographic`` also multiplexes the console
3840    and the monitor to stdio.
3841
3842    There is currently no support for multiplexing in the other
3843    direction (where a single QEMU front end takes input and output from
3844    multiple chardevs).
3845
3846    Every backend supports the ``logfile`` option, which supplies the
3847    path to a file to record all data transmitted via the backend. The
3848    ``logappend`` option controls whether the log file will be truncated
3849    or appended to when opened.
3850
3851The available backends are:
3852
3853``-chardev null,id=id``
3854    A void device. This device will not emit any data, and will drop any
3855    data it receives. The null backend does not take any options.
3856
3857``-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]``
3858    Create a two-way stream socket, which can be either a TCP or a unix
3859    socket. A unix socket will be created if ``path`` is specified.
3860    Behaviour is undefined if TCP options are specified for a unix
3861    socket.
3862
3863    ``server=on|off`` specifies that the socket shall be a listening socket.
3864
3865    ``wait=on|off`` specifies that QEMU should not block waiting for a client
3866    to connect to a listening socket.
3867
3868    ``telnet=on|off`` specifies that traffic on the socket should interpret
3869    telnet escape sequences.
3870
3871    ``websocket=on|off`` specifies that the socket uses WebSocket protocol for
3872    communication.
3873
3874    ``reconnect`` sets the timeout for reconnecting on non-server
3875    sockets when the remote end goes away. qemu will delay this many
3876    seconds and then attempt to reconnect. Zero disables reconnecting,
3877    and is the default.
3878
3879    ``tls-creds`` requests enablement of the TLS protocol for
3880    encryption, and specifies the id of the TLS credentials to use for
3881    the handshake. The credentials must be previously created with the
3882    ``-object tls-creds`` argument.
3883
3884    ``tls-auth`` provides the ID of the QAuthZ authorization object
3885    against which the client's x509 distinguished name will be
3886    validated. This object is only resolved at time of use, so can be
3887    deleted and recreated on the fly while the chardev server is active.
3888    If missing, it will default to denying access.
3889
3890    TCP and unix socket options are given below:
3891
3892    ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]``
3893        ``host`` for a listening socket specifies the local address to
3894        be bound. For a connecting socket species the remote host to
3895        connect to. ``host`` is optional for listening sockets. If not
3896        specified it defaults to ``0.0.0.0``.
3897
3898        ``port`` for a listening socket specifies the local port to be
3899        bound. For a connecting socket specifies the port on the remote
3900        host to connect to. ``port`` can be given as either a port
3901        number or a service name. ``port`` is required.
3902
3903        ``to`` is only relevant to listening sockets. If it is
3904        specified, and ``port`` cannot be bound, QEMU will attempt to
3905        bind to subsequent ports up to and including ``to`` until it
3906        succeeds. ``to`` must be specified as a port number.
3907
3908        ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4
3909        or IPv6 must be used. If neither is specified the socket may
3910        use either protocol.
3911
3912        ``nodelay=on|off`` disables the Nagle algorithm.
3913
3914    ``unix options: path=path[,abstract=on|off][,tight=on|off]``
3915        ``path`` specifies the local path of the unix socket. ``path``
3916        is required.
3917        ``abstract=on|off`` specifies the use of the abstract socket namespace,
3918        rather than the filesystem.  Optional, defaults to false.
3919        ``tight=on|off`` sets the socket length of abstract sockets to their minimum,
3920        rather than the full sun_path length.  Optional, defaults to true.
3921
3922``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]``
3923    Sends all traffic from the guest to a remote host over UDP.
3924
3925    ``host`` specifies the remote host to connect to. If not specified
3926    it defaults to ``localhost``.
3927
3928    ``port`` specifies the port on the remote host to connect to.
3929    ``port`` is required.
3930
3931    ``localaddr`` specifies the local address to bind to. If not
3932    specified it defaults to ``0.0.0.0``.
3933
3934    ``localport`` specifies the local port to bind to. If not specified
3935    any available local port will be used.
3936
3937    ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used.
3938    If neither is specified the device may use either protocol.
3939
3940``-chardev msmouse,id=id``
3941    Forward QEMU's emulated msmouse events to the guest. ``msmouse``
3942    does not take any options.
3943
3944``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
3945    Connect to a QEMU text console. ``vc`` may optionally be given a
3946    specific size.
3947
3948    ``width`` and ``height`` specify the width and height respectively
3949    of the console, in pixels.
3950
3951    ``cols`` and ``rows`` specify that the console be sized to fit a
3952    text console with the given dimensions.
3953
3954``-chardev ringbuf,id=id[,size=size]``
3955    Create a ring buffer with fixed size ``size``. size must be a power
3956    of two and defaults to ``64K``.
3957
3958``-chardev file,id=id,path=path[,input-path=input-path]``
3959    Log all traffic received from the guest to a file.
3960
3961    ``path`` specifies the path of the file to be opened. This file will
3962    be created if it does not already exist, and overwritten if it does.
3963    ``path`` is required.
3964
3965    If ``input-path`` is specified, this is the path of a second file
3966    which will be used for input. If ``input-path`` is not specified,
3967    no input will be available from the chardev.
3968
3969    Note that ``input-path`` is not supported on Windows hosts.
3970
3971``-chardev pipe,id=id,path=path``
3972    Create a two-way connection to the guest. The behaviour differs
3973    slightly between Windows hosts and other hosts:
3974
3975    On Windows, a single duplex pipe will be created at
3976    ``\\.pipe\path``.
3977
3978    On other hosts, 2 pipes will be created called ``path.in`` and
3979    ``path.out``. Data written to ``path.in`` will be received by the
3980    guest. Data written by the guest can be read from ``path.out``. QEMU
3981    will not create these fifos, and requires them to be present.
3982
3983    ``path`` forms part of the pipe path as described above. ``path`` is
3984    required.
3985
3986``-chardev console,id=id``
3987    Send traffic from the guest to QEMU's standard output. ``console``
3988    does not take any options.
3989
3990    ``console`` is only available on Windows hosts.
3991
3992``-chardev serial,id=id,path=path``
3993    Send traffic from the guest to a serial device on the host.
3994
3995    On Unix hosts serial will actually accept any tty device, not only
3996    serial lines.
3997
3998    ``path`` specifies the name of the serial device to open.
3999
4000``-chardev pty,id=id``
4001    Create a new pseudo-terminal on the host and connect to it. ``pty``
4002    does not take any options.
4003
4004    ``pty`` is not available on Windows hosts.
4005
4006``-chardev stdio,id=id[,signal=on|off]``
4007    Connect to standard input and standard output of the QEMU process.
4008
4009    ``signal`` controls if signals are enabled on the terminal, that
4010    includes exiting QEMU with the key sequence Control-c. This option
4011    is enabled by default, use ``signal=off`` to disable it.
4012
4013``-chardev braille,id=id``
4014    Connect to a local BrlAPI server. ``braille`` does not take any
4015    options.
4016
4017``-chardev parallel,id=id,path=path``
4018  \
4019    ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
4020    hosts.
4021
4022    Connect to a local parallel port.
4023
4024    ``path`` specifies the path to the parallel port device. ``path`` is
4025    required.
4026
4027``-chardev spicevmc,id=id,debug=debug,name=name``
4028    ``spicevmc`` is only available when spice support is built in.
4029
4030    ``debug`` debug level for spicevmc
4031
4032    ``name`` name of spice channel to connect to
4033
4034    Connect to a spice virtual machine channel, such as vdiport.
4035
4036``-chardev spiceport,id=id,debug=debug,name=name``
4037    ``spiceport`` is only available when spice support is built in.
4038
4039    ``debug`` debug level for spicevmc
4040
4041    ``name`` name of spice port to connect to
4042
4043    Connect to a spice port, allowing a Spice client to handle the
4044    traffic identified by a name (preferably a fqdn).
4045ERST
4046
4047DEFHEADING()
4048
4049#ifdef CONFIG_TPM
4050DEFHEADING(TPM device options:)
4051
4052DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
4053    "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
4054    "                use path to provide path to a character device; default is /dev/tpm0\n"
4055    "                use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
4056    "                not provided it will be searched for in /sys/class/misc/tpm?/device\n"
4057    "-tpmdev emulator,id=id,chardev=dev\n"
4058    "                configure the TPM device using chardev backend\n",
4059    QEMU_ARCH_ALL)
4060SRST
4061The general form of a TPM device option is:
4062
4063``-tpmdev backend,id=id[,options]``
4064    The specific backend type will determine the applicable options. The
4065    ``-tpmdev`` option creates the TPM backend and requires a
4066    ``-device`` option that specifies the TPM frontend interface model.
4067
4068    Use ``-tpmdev help`` to print all available TPM backend types.
4069
4070The available backends are:
4071
4072``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
4073    (Linux-host only) Enable access to the host's TPM using the
4074    passthrough driver.
4075
4076    ``path`` specifies the path to the host's TPM device, i.e., on a
4077    Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
4078    default ``/dev/tpm0`` is used.
4079
4080    ``cancel-path`` specifies the path to the host TPM device's sysfs
4081    entry allowing for cancellation of an ongoing TPM command.
4082    ``cancel-path`` is optional and by default QEMU will search for the
4083    sysfs entry to use.
4084
4085    Some notes about using the host's TPM with the passthrough driver:
4086
4087    The TPM device accessed by the passthrough driver must not be used
4088    by any other application on the host.
4089
4090    Since the host's firmware (BIOS/UEFI) has already initialized the
4091    TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
4092    the TPM again and may therefore not show a TPM-specific menu that
4093    would otherwise allow the user to configure the TPM, e.g., allow the
4094    user to enable/disable or activate/deactivate the TPM. Further, if
4095    TPM ownership is released from within a VM then the host's TPM will
4096    get disabled and deactivated. To enable and activate the TPM again
4097    afterwards, the host has to be rebooted and the user is required to
4098    enter the firmware's menu to enable and activate the TPM. If the TPM
4099    is left disabled and/or deactivated most TPM commands will fail.
4100
4101    To create a passthrough TPM use the following two options:
4102
4103    ::
4104
4105        -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
4106
4107    Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
4108    ``tpmdev=tpm0`` in the device option.
4109
4110``-tpmdev emulator,id=id,chardev=dev``
4111    (Linux-host only) Enable access to a TPM emulator using Unix domain
4112    socket based chardev backend.
4113
4114    ``chardev`` specifies the unique ID of a character device backend
4115    that provides connection to the software TPM server.
4116
4117    To create a TPM emulator backend device with chardev socket backend:
4118
4119    ::
4120
4121        -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
4122ERST
4123
4124DEFHEADING()
4125
4126#endif
4127
4128DEFHEADING(Boot Image or Kernel specific:)
4129SRST
4130There are broadly 4 ways you can boot a system with QEMU.
4131
4132 - specify a firmware and let it control finding a kernel
4133 - specify a firmware and pass a hint to the kernel to boot
4134 - direct kernel image boot
4135 - manually load files into the guest's address space
4136
4137The third method is useful for quickly testing kernels but as there is
4138no firmware to pass configuration information to the kernel the
4139hardware must either be probeable, the kernel built for the exact
4140configuration or passed some configuration data (e.g. a DTB blob)
4141which tells the kernel what drivers it needs. This exact details are
4142often hardware specific.
4143
4144The final method is the most generic way of loading images into the
4145guest address space and used mostly for ``bare metal`` type
4146development where the reset vectors of the processor are taken into
4147account.
4148
4149ERST
4150
4151SRST
4152
4153For x86 machines and some other architectures ``-bios`` will generally
4154do the right thing with whatever it is given. For other machines the
4155more strict ``-pflash`` option needs an image that is sized for the
4156flash device for the given machine type.
4157
4158Please see the :ref:`system-targets-ref` section of the manual for
4159more detailed documentation.
4160
4161ERST
4162
4163DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
4164    "-bios file      set the filename for the BIOS\n", QEMU_ARCH_ALL)
4165SRST
4166``-bios file``
4167    Set the filename for the BIOS.
4168ERST
4169
4170DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
4171    "-pflash file    use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
4172SRST
4173``-pflash file``
4174    Use file as a parallel flash image.
4175ERST
4176
4177SRST
4178
4179The kernel options were designed to work with Linux kernels although
4180other things (like hypervisors) can be packaged up as a kernel
4181executable image. The exact format of a executable image is usually
4182architecture specific.
4183
4184The way in which the kernel is started (what address it is loaded at,
4185what if any information is passed to it via CPU registers, the state
4186of the hardware when it is started, and so on) is also architecture
4187specific. Typically it follows the specification laid down by the
4188Linux kernel for how kernels for that architecture must be started.
4189
4190ERST
4191
4192DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
4193    "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
4194SRST
4195``-kernel bzImage``
4196    Use bzImage as kernel image. The kernel can be either a Linux kernel
4197    or in multiboot format.
4198ERST
4199
4200DEF("append", HAS_ARG, QEMU_OPTION_append, \
4201    "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
4202SRST
4203``-append cmdline``
4204    Use cmdline as kernel command line
4205ERST
4206
4207DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
4208           "-initrd file    use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
4209SRST(initrd)
4210
4211``-initrd file``
4212    Use file as initial ram disk.
4213
4214``-initrd "file1 arg=foo,file2"``
4215    This syntax is only available with multiboot.
4216
4217    Use file1 and file2 as modules and pass ``arg=foo`` as parameter to the
4218    first module. Commas can be provided in module parameters by doubling
4219    them on the command line to escape them:
4220
4221``-initrd "bzImage earlyprintk=xen,,keep root=/dev/xvda1,initrd.img"``
4222    Multiboot only. Use bzImage as the first module with
4223    "``earlyprintk=xen,keep root=/dev/xvda1``" as its command line,
4224    and initrd.img as the second module.
4225
4226ERST
4227
4228DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
4229    "-dtb    file    use 'file' as device tree image\n", QEMU_ARCH_ALL)
4230SRST
4231``-dtb file``
4232    Use file as a device tree binary (dtb) image and pass it to the
4233    kernel on boot.
4234ERST
4235
4236SRST
4237
4238Finally you can also manually load images directly into the address
4239space of the guest. This is most useful for developers who already
4240know the layout of their guest and take care to ensure something sane
4241will happen when the reset vector executes.
4242
4243The generic loader can be invoked by using the loader device:
4244
4245``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]``
4246
4247there is also the guest loader which operates in a similar way but
4248tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where
4249the guest image is:
4250
4251``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]``
4252
4253ERST
4254
4255DEFHEADING()
4256
4257DEFHEADING(Debug/Expert options:)
4258
4259DEF("compat", HAS_ARG, QEMU_OPTION_compat,
4260    "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n"
4261    "                Policy for handling deprecated management interfaces\n"
4262    "-compat [unstable-input=accept|reject|crash][,unstable-output=accept|hide]\n"
4263    "                Policy for handling unstable management interfaces\n",
4264    QEMU_ARCH_ALL)
4265SRST
4266``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]``
4267    Set policy for handling deprecated management interfaces (experimental):
4268
4269    ``deprecated-input=accept`` (default)
4270        Accept deprecated commands and arguments
4271    ``deprecated-input=reject``
4272        Reject deprecated commands and arguments
4273    ``deprecated-input=crash``
4274        Crash on deprecated commands and arguments
4275    ``deprecated-output=accept`` (default)
4276        Emit deprecated command results and events
4277    ``deprecated-output=hide``
4278        Suppress deprecated command results and events
4279
4280    Limitation: covers only syntactic aspects of QMP.
4281
4282``-compat [unstable-input=@var{input-policy}][,unstable-output=@var{output-policy}]``
4283    Set policy for handling unstable management interfaces (experimental):
4284
4285    ``unstable-input=accept`` (default)
4286        Accept unstable commands and arguments
4287    ``unstable-input=reject``
4288        Reject unstable commands and arguments
4289    ``unstable-input=crash``
4290        Crash on unstable commands and arguments
4291    ``unstable-output=accept`` (default)
4292        Emit unstable command results and events
4293    ``unstable-output=hide``
4294        Suppress unstable command results and events
4295
4296    Limitation: covers only syntactic aspects of QMP.
4297ERST
4298
4299DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
4300    "-fw_cfg [name=]<name>,file=<file>\n"
4301    "                add named fw_cfg entry with contents from file\n"
4302    "-fw_cfg [name=]<name>,string=<str>\n"
4303    "                add named fw_cfg entry with contents from string\n",
4304    QEMU_ARCH_ALL)
4305SRST
4306``-fw_cfg [name=]name,file=file``
4307    Add named fw\_cfg entry with contents from file file.
4308    If the filename contains comma, you must double it (for instance,
4309    "file=my,,file" to use file "my,file").
4310
4311``-fw_cfg [name=]name,string=str``
4312    Add named fw\_cfg entry with contents from string str.
4313    If the string contains comma, you must double it (for instance,
4314    "string=my,,string" to use file "my,string").
4315
4316    The terminating NUL character of the contents of str will not be
4317    included as part of the fw\_cfg item data. To insert contents with
4318    embedded NUL characters, you have to use the file parameter.
4319
4320    The fw\_cfg entries are passed by QEMU through to the guest.
4321
4322    Example:
4323
4324    ::
4325
4326            -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
4327
4328    creates an fw\_cfg entry named opt/com.mycompany/blob with contents
4329    from ./my\_blob.bin.
4330ERST
4331
4332DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
4333    "-serial dev     redirect the serial port to char device 'dev'\n",
4334    QEMU_ARCH_ALL)
4335SRST
4336``-serial dev``
4337    Redirect the virtual serial port to host character device dev. The
4338    default device is ``vc`` in graphical mode and ``stdio`` in non
4339    graphical mode.
4340
4341    This option can be used several times to simulate multiple serial
4342    ports.
4343
4344    You can use ``-serial none`` to suppress the creation of default
4345    serial devices.
4346
4347    Available character devices are:
4348
4349    ``vc[:WxH]``
4350        Virtual console. Optionally, a width and height can be given in
4351        pixel with
4352
4353        ::
4354
4355            vc:800x600
4356
4357        It is also possible to specify width or height in characters:
4358
4359        ::
4360
4361            vc:80Cx24C
4362
4363    ``pty``
4364        [Linux only] Pseudo TTY (a new PTY is automatically allocated)
4365
4366    ``none``
4367        No device is allocated. Note that for machine types which
4368        emulate systems where a serial device is always present in
4369        real hardware, this may be equivalent to the ``null`` option,
4370        in that the serial device is still present but all output
4371        is discarded. For boards where the number of serial ports is
4372        truly variable, this suppresses the creation of the device.
4373
4374    ``null``
4375        A guest will see the UART or serial device as present in the
4376        machine, but all output is discarded, and there is no input.
4377        Conceptually equivalent to redirecting the output to ``/dev/null``.
4378
4379    ``chardev:id``
4380        Use a named character device defined with the ``-chardev``
4381        option.
4382
4383    ``/dev/XXX``
4384        [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
4385        port parameters are set according to the emulated ones.
4386
4387    ``/dev/parportN``
4388        [Linux only, parallel port only] Use host parallel port N.
4389        Currently SPP and EPP parallel port features can be used.
4390
4391    ``file:filename``
4392        Write output to filename. No character can be read.
4393
4394    ``stdio``
4395        [Unix only] standard input/output
4396
4397    ``pipe:filename``
4398        name pipe filename
4399
4400    ``COMn``
4401        [Windows only] Use host serial port n
4402
4403    ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
4404        This implements UDP Net Console. When remote\_host or src\_ip
4405        are not specified they default to ``0.0.0.0``. When not using a
4406        specified src\_port a random port is automatically chosen.
4407
4408        If you just want a simple readonly console you can use
4409        ``netcat`` or ``nc``, by starting QEMU with:
4410        ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
4411        QEMU writes something to that port it will appear in the
4412        netconsole session.
4413
4414        If you plan to send characters back via netconsole or you want
4415        to stop and start QEMU a lot of times, you should have QEMU use
4416        the same source port each time by using something like ``-serial
4417        udp::4555@:4556`` to QEMU. Another approach is to use a patched
4418        version of netcat which can listen to a TCP port and send and
4419        receive characters via udp. If you have a patched version of
4420        netcat which activates telnet remote echo and single char
4421        transfer, then you can use the following options to set up a
4422        netcat redirector to allow telnet on port 5555 to access the
4423        QEMU port.
4424
4425        ``QEMU Options:``
4426            -serial udp::4555@:4556
4427
4428        ``netcat options:``
4429            -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
4430
4431        ``telnet options:``
4432            localhost 5555
4433
4434    ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]``
4435        The TCP Net Console has two modes of operation. It can send the
4436        serial I/O to a location or wait for a connection from a
4437        location. By default the TCP Net Console is sent to host at the
4438        port. If you use the ``server=on`` option QEMU will wait for a client
4439        socket application to connect to the port before continuing,
4440        unless the ``wait=on|off`` option was specified. The ``nodelay=on|off``
4441        option disables the Nagle buffering algorithm. The ``reconnect=on``
4442        option only applies if ``server=no`` is set, if the connection goes
4443        down it will attempt to reconnect at the given interval. If host
4444        is omitted, 0.0.0.0 is assumed. Only one TCP connection at a
4445        time is accepted. You can use ``telnet=on`` to connect to the
4446        corresponding character device.
4447
4448        ``Example to send tcp console to 192.168.0.2 port 4444``
4449            -serial tcp:192.168.0.2:4444
4450
4451        ``Example to listen and wait on port 4444 for connection``
4452            -serial tcp::4444,server=on
4453
4454        ``Example to not wait and listen on ip 192.168.0.100 port 4444``
4455            -serial tcp:192.168.0.100:4444,server=on,wait=off
4456
4457    ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]``
4458        The telnet protocol is used instead of raw tcp sockets. The
4459        options work the same as if you had specified ``-serial tcp``.
4460        The difference is that the port acts like a telnet server or
4461        client using telnet option negotiation. This will also allow you
4462        to send the MAGIC\_SYSRQ sequence if you use a telnet that
4463        supports sending the break sequence. Typically in unix telnet
4464        you do it with Control-] and then type "send break" followed by
4465        pressing the enter key.
4466
4467    ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]``
4468        The WebSocket protocol is used instead of raw tcp socket. The
4469        port acts as a WebSocket server. Client mode is not supported.
4470
4471    ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]``
4472        A unix domain socket is used instead of a tcp socket. The option
4473        works the same as if you had specified ``-serial tcp`` except
4474        the unix domain socket path is used for connections.
4475
4476    ``mon:dev_string``
4477        This is a special option to allow the monitor to be multiplexed
4478        onto another serial port. The monitor is accessed with key
4479        sequence of Control-a and then pressing c. dev\_string should be
4480        any one of the serial devices specified above. An example to
4481        multiplex the monitor onto a telnet server listening on port
4482        4444 would be:
4483
4484        ``-serial mon:telnet::4444,server=on,wait=off``
4485
4486        When the monitor is multiplexed to stdio in this way, Ctrl+C
4487        will not terminate QEMU any more but will be passed to the guest
4488        instead.
4489
4490    ``braille``
4491        Braille device. This will use BrlAPI to display the braille
4492        output on a real or fake device.
4493
4494    ``msmouse``
4495        Three button serial mouse. Configure the guest to use Microsoft
4496        protocol.
4497ERST
4498
4499DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
4500    "-parallel dev   redirect the parallel port to char device 'dev'\n",
4501    QEMU_ARCH_ALL)
4502SRST
4503``-parallel dev``
4504    Redirect the virtual parallel port to host device dev (same devices
4505    as the serial port). On Linux hosts, ``/dev/parportN`` can be used
4506    to use hardware devices connected on the corresponding host parallel
4507    port.
4508
4509    This option can be used several times to simulate up to 3 parallel
4510    ports.
4511
4512    Use ``-parallel none`` to disable all parallel ports.
4513ERST
4514
4515DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
4516    "-monitor dev    redirect the monitor to char device 'dev'\n",
4517    QEMU_ARCH_ALL)
4518SRST
4519``-monitor dev``
4520    Redirect the monitor to host device dev (same devices as the serial
4521    port). The default device is ``vc`` in graphical mode and ``stdio``
4522    in non graphical mode. Use ``-monitor none`` to disable the default
4523    monitor.
4524ERST
4525DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
4526    "-qmp dev        like -monitor but opens in 'control' mode\n",
4527    QEMU_ARCH_ALL)
4528SRST
4529``-qmp dev``
4530    Like ``-monitor`` but opens in 'control' mode. For example, to make
4531    QMP available on localhost port 4444::
4532
4533        -qmp tcp:localhost:4444,server=on,wait=off
4534
4535    Not all options are configurable via this syntax; for maximum
4536    flexibility use the ``-mon`` option and an accompanying ``-chardev``.
4537
4538ERST
4539DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
4540    "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
4541    QEMU_ARCH_ALL)
4542SRST
4543``-qmp-pretty dev``
4544    Like ``-qmp`` but uses pretty JSON formatting.
4545ERST
4546
4547DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
4548    "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
4549SRST
4550``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
4551    Set up a monitor connected to the chardev ``name``.
4552    QEMU supports two monitors: the Human Monitor Protocol
4553    (HMP; for human interaction), and the QEMU Monitor Protocol
4554    (QMP; a JSON RPC-style protocol).
4555    The default is HMP; ``mode=control`` selects QMP instead.
4556    ``pretty`` is only valid when ``mode=control``,
4557    turning on JSON pretty printing to ease
4558    human reading and debugging.
4559
4560    For example::
4561
4562      -chardev socket,id=mon1,host=localhost,port=4444,server=on,wait=off \
4563      -mon chardev=mon1,mode=control,pretty=on
4564
4565    enables the QMP monitor on localhost port 4444 with pretty-printing.
4566ERST
4567
4568DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
4569    "-debugcon dev   redirect the debug console to char device 'dev'\n",
4570    QEMU_ARCH_ALL)
4571SRST
4572``-debugcon dev``
4573    Redirect the debug console to host device dev (same devices as the
4574    serial port). The debug console is an I/O port which is typically
4575    port 0xe9; writing to that I/O port sends output to this device. The
4576    default device is ``vc`` in graphical mode and ``stdio`` in non
4577    graphical mode.
4578ERST
4579
4580DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
4581    "-pidfile file   write PID to 'file'\n", QEMU_ARCH_ALL)
4582SRST
4583``-pidfile file``
4584    Store the QEMU process PID in file. It is useful if you launch QEMU
4585    from a script.
4586ERST
4587
4588DEF("preconfig", 0, QEMU_OPTION_preconfig, \
4589    "--preconfig     pause QEMU before machine is initialized (experimental)\n",
4590    QEMU_ARCH_ALL)
4591SRST
4592``--preconfig``
4593    Pause QEMU for interactive configuration before the machine is
4594    created, which allows querying and configuring properties that will
4595    affect machine initialization. Use QMP command 'x-exit-preconfig' to
4596    exit the preconfig state and move to the next state (i.e. run guest
4597    if -S isn't used or pause the second time if -S is used). This
4598    option is experimental.
4599ERST
4600
4601DEF("S", 0, QEMU_OPTION_S, \
4602    "-S              freeze CPU at startup (use 'c' to start execution)\n",
4603    QEMU_ARCH_ALL)
4604SRST
4605``-S``
4606    Do not start CPU at startup (you must type 'c' in the monitor).
4607ERST
4608
4609DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
4610    "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
4611    "                run qemu with overcommit hints\n"
4612    "                mem-lock=on|off controls memory lock support (default: off)\n"
4613    "                cpu-pm=on|off controls cpu power management (default: off)\n",
4614    QEMU_ARCH_ALL)
4615SRST
4616``-overcommit mem-lock=on|off``
4617  \
4618``-overcommit cpu-pm=on|off``
4619    Run qemu with hints about host resource overcommit. The default is
4620    to assume that host overcommits all resources.
4621
4622    Locking qemu and guest memory can be enabled via ``mem-lock=on``
4623    (disabled by default). This works when host memory is not
4624    overcommitted and reduces the worst-case latency for guest.
4625
4626    Guest ability to manage power state of host cpus (increasing latency
4627    for other processes on the same host cpu, but decreasing latency for
4628    guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
4629    works best when host CPU is not overcommitted. When used, host
4630    estimates of CPU cycle and power utilization will be incorrect, not
4631    taking into account guest idle time.
4632ERST
4633
4634DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
4635    "-gdb dev        accept gdb connection on 'dev'. (QEMU defaults to starting\n"
4636    "                the guest without waiting for gdb to connect; use -S too\n"
4637    "                if you want it to not start execution.)\n",
4638    QEMU_ARCH_ALL)
4639SRST
4640``-gdb dev``
4641    Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter
4642    in the System Emulation Users Guide). Note that this option does not pause QEMU
4643    execution -- if you want QEMU to not start the guest until you
4644    connect with gdb and issue a ``continue`` command, you will need to
4645    also pass the ``-S`` option to QEMU.
4646
4647    The most usual configuration is to listen on a local TCP socket::
4648
4649        -gdb tcp::3117
4650
4651    but you can specify other backends; UDP, pseudo TTY, or even stdio
4652    are all reasonable use cases. For example, a stdio connection
4653    allows you to start QEMU from within gdb and establish the
4654    connection via a pipe:
4655
4656    .. parsed-literal::
4657
4658        (gdb) target remote | exec |qemu_system| -gdb stdio ...
4659ERST
4660
4661DEF("s", 0, QEMU_OPTION_s, \
4662    "-s              shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
4663    QEMU_ARCH_ALL)
4664SRST
4665``-s``
4666    Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
4667    (see the :ref:`GDB usage` chapter in the System Emulation Users Guide).
4668ERST
4669
4670DEF("d", HAS_ARG, QEMU_OPTION_d, \
4671    "-d item1,...    enable logging of specified items (use '-d help' for a list of log items)\n",
4672    QEMU_ARCH_ALL)
4673SRST
4674``-d item1[,...]``
4675    Enable logging of specified items. Use '-d help' for a list of log
4676    items.
4677ERST
4678
4679DEF("D", HAS_ARG, QEMU_OPTION_D, \
4680    "-D logfile      output log to logfile (default stderr)\n",
4681    QEMU_ARCH_ALL)
4682SRST
4683``-D logfile``
4684    Output log in logfile instead of to stderr
4685ERST
4686
4687DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
4688    "-dfilter range,..  filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
4689    QEMU_ARCH_ALL)
4690SRST
4691``-dfilter range1[,...]``
4692    Filter debug output to that relevant to a range of target addresses.
4693    The filter spec can be either start+size, start-size or start..end
4694    where start end and size are the addresses and sizes required. For
4695    example:
4696
4697    ::
4698
4699            -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
4700
4701    Will dump output for any code in the 0x1000 sized block starting at
4702    0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
4703    another 0x1000 sized block starting at 0xffffffc00005f000.
4704ERST
4705
4706DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
4707    "-seed number       seed the pseudo-random number generator\n",
4708    QEMU_ARCH_ALL)
4709SRST
4710``-seed number``
4711    Force the guest to use a deterministic pseudo-random number
4712    generator, seeded with number. This does not affect crypto routines
4713    within the host.
4714ERST
4715
4716DEF("L", HAS_ARG, QEMU_OPTION_L, \
4717    "-L path         set the directory for the BIOS, VGA BIOS and keymaps\n",
4718    QEMU_ARCH_ALL)
4719SRST
4720``-L  path``
4721    Set the directory for the BIOS, VGA BIOS and keymaps.
4722
4723    To list all the data directories, use ``-L help``.
4724ERST
4725
4726DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
4727    "-enable-kvm     enable KVM full virtualization support\n",
4728    QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC |
4729    QEMU_ARCH_RISCV | QEMU_ARCH_S390X)
4730SRST
4731``-enable-kvm``
4732    Enable KVM full virtualization support. This option is only
4733    available if KVM support is enabled when compiling.
4734ERST
4735
4736DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
4737    "-xen-domid id   specify xen guest domain id\n",
4738    QEMU_ARCH_ARM | QEMU_ARCH_I386)
4739DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
4740    "-xen-attach     attach to existing xen domain\n"
4741    "                libxl will use this when starting QEMU\n",
4742    QEMU_ARCH_ARM | QEMU_ARCH_I386)
4743DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
4744    "-xen-domid-restrict     restrict set of available xen operations\n"
4745    "                        to specified domain id. (Does not affect\n"
4746    "                        xenpv machine type).\n",
4747    QEMU_ARCH_ARM | QEMU_ARCH_I386)
4748SRST
4749``-xen-domid id``
4750    Specify xen guest domain id (XEN only).
4751
4752``-xen-attach``
4753    Attach to existing xen domain. libxl will use this when starting
4754    QEMU (XEN only). Restrict set of available xen operations to
4755    specified domain id (XEN only).
4756ERST
4757
4758DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
4759    "-no-reboot      exit instead of rebooting\n", QEMU_ARCH_ALL)
4760SRST
4761``-no-reboot``
4762    Exit instead of rebooting.
4763ERST
4764
4765DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
4766    "-no-shutdown    stop before shutdown\n", QEMU_ARCH_ALL)
4767SRST
4768``-no-shutdown``
4769    Don't exit QEMU on guest shutdown, but instead only stop the
4770    emulation. This allows for instance switching to monitor to commit
4771    changes to the disk image.
4772ERST
4773
4774DEF("action", HAS_ARG, QEMU_OPTION_action,
4775    "-action reboot=reset|shutdown\n"
4776    "                   action when guest reboots [default=reset]\n"
4777    "-action shutdown=poweroff|pause\n"
4778    "                   action when guest shuts down [default=poweroff]\n"
4779    "-action panic=pause|shutdown|exit-failure|none\n"
4780    "                   action when guest panics [default=shutdown]\n"
4781    "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
4782    "                   action when watchdog fires [default=reset]\n",
4783    QEMU_ARCH_ALL)
4784SRST
4785``-action event=action``
4786    The action parameter serves to modify QEMU's default behavior when
4787    certain guest events occur. It provides a generic method for specifying the
4788    same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown``
4789    parameters.
4790
4791    Examples:
4792
4793    ``-action panic=none``
4794    ``-action reboot=shutdown,shutdown=pause``
4795    ``-device i6300esb -action watchdog=pause``
4796
4797ERST
4798
4799DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
4800    "-loadvm [tag|id]\n" \
4801    "                start right away with a saved state (loadvm in monitor)\n",
4802    QEMU_ARCH_ALL)
4803SRST
4804``-loadvm file``
4805    Start right away with a saved state (``loadvm`` in monitor)
4806ERST
4807
4808#ifndef _WIN32
4809DEF("daemonize", 0, QEMU_OPTION_daemonize, \
4810    "-daemonize      daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
4811#endif
4812SRST
4813``-daemonize``
4814    Daemonize the QEMU process after initialization. QEMU will not
4815    detach from standard IO until it is ready to receive connections on
4816    any of its devices. This option is a useful way for external
4817    programs to launch QEMU without having to cope with initialization
4818    race conditions.
4819ERST
4820
4821DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
4822    "-option-rom rom load a file, rom, into the option ROM space\n",
4823    QEMU_ARCH_ALL)
4824SRST
4825``-option-rom file``
4826    Load the contents of file as an option ROM. This option is useful to
4827    load things like EtherBoot.
4828ERST
4829
4830DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
4831    "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
4832    "                set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
4833    QEMU_ARCH_ALL)
4834
4835SRST
4836``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
4837    Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
4838    the current UTC or local time, respectively. ``localtime`` is
4839    required for correct date in MS-DOS or Windows. To start at a
4840    specific point in time, provide datetime in the format
4841    ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.
4842
4843    By default the RTC is driven by the host system time. This allows
4844    using of the RTC as accurate reference clock inside the guest,
4845    specifically if the host time is smoothly following an accurate
4846    external reference clock, e.g. via NTP. If you want to isolate the
4847    guest time from the host, you can set ``clock`` to ``rt`` instead,
4848    which provides a host monotonic clock if host support it. To even
4849    prevent the RTC from progressing during suspension, you can set
4850    ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
4851    recommended especially in icount mode in order to preserve
4852    determinism; however, note that in icount mode the speed of the
4853    virtual clock is variable and can in general differ from the host
4854    clock.
4855
4856    Enable ``driftfix`` (i386 targets only) if you experience time drift
4857    problems, specifically with Windows' ACPI HAL. This option will try
4858    to figure out how many timer interrupts were not processed by the
4859    Windows guest and will re-inject them.
4860ERST
4861
4862DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
4863    "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \
4864    "                enable virtual instruction counter with 2^N clock ticks per\n" \
4865    "                instruction, enable aligning the host and virtual clocks\n" \
4866    "                or disable real time cpu sleeping, and optionally enable\n" \
4867    "                record-and-replay mode\n", QEMU_ARCH_ALL)
4868SRST
4869``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]``
4870    Enable virtual instruction counter. The virtual cpu will execute one
4871    instruction every 2^N ns of virtual time. If ``auto`` is specified
4872    then the virtual cpu speed will be automatically adjusted to keep
4873    virtual time within a few seconds of real time.
4874
4875    Note that while this option can give deterministic behavior, it does
4876    not provide cycle accurate emulation. Modern CPUs contain
4877    superscalar out of order cores with complex cache hierarchies. The
4878    number of instructions executed often has little or no correlation
4879    with actual performance.
4880
4881    When the virtual cpu is sleeping, the virtual time will advance at
4882    default speed unless ``sleep=on`` is specified. With
4883    ``sleep=on``, the virtual time will jump to the next timer
4884    deadline instantly whenever the virtual cpu goes to sleep mode and
4885    will not advance if no timer is enabled. This behavior gives
4886    deterministic execution times from the guest point of view.
4887    The default if icount is enabled is ``sleep=off``.
4888    ``sleep=on`` cannot be used together with either ``shift=auto``
4889    or ``align=on``.
4890
4891    ``align=on`` will activate the delay algorithm which will try to
4892    synchronise the host clock and the virtual clock. The goal is to
4893    have a guest running at the real frequency imposed by the shift
4894    option. Whenever the guest clock is behind the host clock and if
4895    ``align=on`` is specified then we print a message to the user to
4896    inform about the delay. Currently this option does not work when
4897    ``shift`` is ``auto``. Note: The sync algorithm will work for those
4898    shift values for which the guest clock runs ahead of the host clock.
4899    Typically this happens when the shift value is high (how high
4900    depends on the host machine). The default if icount is enabled
4901    is ``align=off``.
4902
4903    When the ``rr`` option is specified deterministic record/replay is
4904    enabled. The ``rrfile=`` option must also be provided to
4905    specify the path to the replay log. In record mode data is written
4906    to this file, and in replay mode it is read back.
4907    If the ``rrsnapshot`` option is given then it specifies a VM snapshot
4908    name. In record mode, a new VM snapshot with the given name is created
4909    at the start of execution recording. In replay mode this option
4910    specifies the snapshot name used to load the initial VM state.
4911ERST
4912
4913DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
4914    "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
4915    "                action when watchdog fires [default=reset]\n",
4916    QEMU_ARCH_ALL)
4917SRST
4918``-watchdog-action action``
4919    The action controls what QEMU will do when the watchdog timer
4920    expires. The default is ``reset`` (forcefully reset the guest).
4921    Other possible actions are: ``shutdown`` (attempt to gracefully
4922    shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
4923    ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
4924    guest), ``debug`` (print a debug message and continue), or ``none``
4925    (do nothing).
4926
4927    Note that the ``shutdown`` action requires that the guest responds
4928    to ACPI signals, which it may not be able to do in the sort of
4929    situations where the watchdog would have expired, and thus
4930    ``-watchdog-action shutdown`` is not recommended for production use.
4931
4932    Examples:
4933
4934    ``-device i6300esb -watchdog-action pause``
4935
4936ERST
4937
4938DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
4939    "-echr chr       set terminal escape character instead of ctrl-a\n",
4940    QEMU_ARCH_ALL)
4941SRST
4942``-echr numeric_ascii_value``
4943    Change the escape character used for switching to the monitor when
4944    using monitor and serial sharing. The default is ``0x01`` when using
4945    the ``-nographic`` option. ``0x01`` is equal to pressing
4946    ``Control-a``. You can select a different character from the ascii
4947    control keys where 1 through 26 map to Control-a through Control-z.
4948    For instance you could use the either of the following to change the
4949    escape character to Control-t.
4950
4951    ``-echr 0x14``; \ ``-echr 20``
4952
4953ERST
4954
4955DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
4956    "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \
4957    "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \
4958    "-incoming unix:socketpath\n" \
4959    "                prepare for incoming migration, listen on\n" \
4960    "                specified protocol and socket address\n" \
4961    "-incoming fd:fd\n" \
4962    "-incoming file:filename[,offset=offset]\n" \
4963    "-incoming exec:cmdline\n" \
4964    "                accept incoming migration on given file descriptor\n" \
4965    "                or from given external command\n" \
4966    "-incoming defer\n" \
4967    "                wait for the URI to be specified via migrate_incoming\n",
4968    QEMU_ARCH_ALL)
4969SRST
4970``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]``
4971  \
4972``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]``
4973    Prepare for incoming migration, listen on a given tcp port.
4974
4975``-incoming unix:socketpath``
4976    Prepare for incoming migration, listen on a given unix socket.
4977
4978``-incoming fd:fd``
4979    Accept incoming migration from a given file descriptor.
4980
4981``-incoming file:filename[,offset=offset]``
4982    Accept incoming migration from a given file starting at offset.
4983    offset allows the common size suffixes, or a 0x prefix, but not both.
4984
4985``-incoming exec:cmdline``
4986    Accept incoming migration as an output from specified external
4987    command.
4988
4989``-incoming defer``
4990    Wait for the URI to be specified via migrate\_incoming. The monitor
4991    can be used to change settings (such as migration parameters) prior
4992    to issuing the migrate\_incoming to allow the migration to begin.
4993ERST
4994
4995DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
4996    "-only-migratable     allow only migratable devices\n", QEMU_ARCH_ALL)
4997SRST
4998``-only-migratable``
4999    Only allow migratable devices. Devices will not be allowed to enter
5000    an unmigratable state.
5001ERST
5002
5003DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
5004    "-nodefaults     don't create default devices\n", QEMU_ARCH_ALL)
5005SRST
5006``-nodefaults``
5007    Don't create default devices. Normally, QEMU sets the default
5008    devices like serial port, parallel port, virtual console, monitor
5009    device, VGA adapter, floppy and CD-ROM drive and others. The
5010    ``-nodefaults`` option will disable all those default devices.
5011ERST
5012
5013#ifndef _WIN32
5014DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
5015    "-runas user     change to user id user just before starting the VM\n" \
5016    "                user can be numeric uid:gid instead\n",
5017    QEMU_ARCH_ALL)
5018#endif
5019SRST
5020``-runas user``
5021    Immediately before starting guest execution, drop root privileges,
5022    switching to the specified user. This option is deprecated, use
5023    ``-run-with user=...`` instead.
5024ERST
5025
5026DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
5027    "-prom-env variable=value\n"
5028    "                set OpenBIOS nvram variables\n",
5029    QEMU_ARCH_PPC | QEMU_ARCH_SPARC)
5030SRST
5031``-prom-env variable=value``
5032    Set OpenBIOS nvram variable to given value (PPC, SPARC only).
5033
5034    ::
5035
5036        qemu-system-sparc -prom-env 'auto-boot?=false' \
5037         -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
5038
5039    ::
5040
5041        qemu-system-ppc -prom-env 'auto-boot?=false' \
5042         -prom-env 'boot-device=hd:2,\yaboot' \
5043         -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
5044ERST
5045DEF("semihosting", 0, QEMU_OPTION_semihosting,
5046    "-semihosting    semihosting mode\n",
5047    QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA |
5048    QEMU_ARCH_MIPS | QEMU_ARCH_RISCV)
5049SRST
5050``-semihosting``
5051    Enable :ref:`Semihosting` mode (ARM, M68K, Xtensa, MIPS, RISC-V only).
5052
5053    .. warning::
5054      Note that this allows guest direct access to the host filesystem, so
5055      should only be used with a trusted guest OS.
5056
5057    See the -semihosting-config option documentation for further
5058    information about the facilities this enables.
5059ERST
5060DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
5061    "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,userspace=on|off][,arg=str[,...]]\n" \
5062    "                semihosting configuration\n",
5063QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA |
5064QEMU_ARCH_MIPS | QEMU_ARCH_RISCV)
5065SRST
5066``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,userspace=on|off][,arg=str[,...]]``
5067    Enable and configure :ref:`Semihosting` (ARM, M68K, Xtensa, MIPS, RISC-V
5068    only).
5069
5070    .. warning::
5071      Note that this allows guest direct access to the host filesystem, so
5072      should only be used with a trusted guest OS.
5073
5074    ``target=native|gdb|auto``
5075        Defines where the semihosting calls will be addressed, to QEMU
5076        (``native``) or to GDB (``gdb``). The default is ``auto``, which
5077        means ``gdb`` during debug sessions and ``native`` otherwise.
5078
5079    ``chardev=str1``
5080        Send the output to a chardev backend output for native or auto
5081        output when not in gdb
5082
5083    ``userspace=on|off``
5084        Allows code running in guest userspace to access the semihosting
5085        interface. The default is that only privileged guest code can
5086        make semihosting calls. Note that setting ``userspace=on`` should
5087        only be used if all guest code is trusted (for example, in
5088        bare-metal test case code).
5089
5090    ``arg=str1,arg=str2,...``
5091        Allows the user to pass input arguments, and can be used
5092        multiple times to build up a list. The old-style
5093        ``-kernel``/``-append`` method of passing a command line is
5094        still supported for backward compatibility. If both the
5095        ``--semihosting-config arg`` and the ``-kernel``/``-append`` are
5096        specified, the former is passed to semihosting as it always
5097        takes precedence.
5098ERST
5099DEF("old-param", 0, QEMU_OPTION_old_param,
5100    "-old-param      old param mode\n", QEMU_ARCH_ARM)
5101SRST
5102``-old-param``
5103    Old param mode (ARM only).
5104ERST
5105
5106DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
5107    "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
5108    "          [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
5109    "                Enable seccomp mode 2 system call filter (default 'off').\n" \
5110    "                use 'obsolete' to allow obsolete system calls that are provided\n" \
5111    "                    by the kernel, but typically no longer used by modern\n" \
5112    "                    C library implementations.\n" \
5113    "                use 'elevateprivileges' to allow or deny the QEMU process ability\n" \
5114    "                    to elevate privileges using set*uid|gid system calls.\n" \
5115    "                    The value 'children' will deny set*uid|gid system calls for\n" \
5116    "                    main QEMU process but will allow forks and execves to run unprivileged\n" \
5117    "                use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
5118    "                     blocking *fork and execve\n" \
5119    "                use 'resourcecontrol' to disable process affinity and schedular priority\n",
5120    QEMU_ARCH_ALL)
5121SRST
5122``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]``
5123    Enable Seccomp mode 2 system call filter. 'on' will enable syscall
5124    filtering and 'off' will disable it. The default is 'off'.
5125
5126    ``obsolete=string``
5127        Enable Obsolete system calls
5128
5129    ``elevateprivileges=string``
5130        Disable set\*uid\|gid system calls
5131
5132    ``spawn=string``
5133        Disable \*fork and execve
5134
5135    ``resourcecontrol=string``
5136        Disable process affinity and schedular priority
5137ERST
5138
5139DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
5140    "-readconfig <file>\n"
5141    "                read config file\n", QEMU_ARCH_ALL)
5142SRST
5143``-readconfig file``
5144    Read device configuration from file. This approach is useful when
5145    you want to spawn QEMU process with many command line options but
5146    you don't want to exceed the command line character limit.
5147ERST
5148
5149DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
5150    "-no-user-config\n"
5151    "                do not load default user-provided config files at startup\n",
5152    QEMU_ARCH_ALL)
5153SRST
5154``-no-user-config``
5155    The ``-no-user-config`` option makes QEMU not load any of the
5156    user-provided config files on sysconfdir.
5157ERST
5158
5159DEF("trace", HAS_ARG, QEMU_OPTION_trace,
5160    "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
5161    "                specify tracing options\n",
5162    QEMU_ARCH_ALL)
5163SRST
5164``-trace [[enable=]pattern][,events=file][,file=file]``
5165  .. include:: ../qemu-option-trace.rst.inc
5166
5167ERST
5168DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
5169    "-plugin [file=]<file>[,<argname>=<argvalue>]\n"
5170    "                load a plugin\n",
5171    QEMU_ARCH_ALL)
5172SRST
5173``-plugin file=file[,argname=argvalue]``
5174    Load a plugin.
5175
5176    ``file=file``
5177        Load the given plugin from a shared library file.
5178
5179    ``argname=argvalue``
5180        Argument passed to the plugin. (Can be given multiple times.)
5181ERST
5182
5183HXCOMM Internal use
5184DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
5185DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
5186
5187#ifdef CONFIG_POSIX
5188DEF("run-with", HAS_ARG, QEMU_OPTION_run_with,
5189    "-run-with [async-teardown=on|off][,chroot=dir][user=username|uid:gid]\n"
5190    "                Set miscellaneous QEMU process lifecycle options:\n"
5191    "                async-teardown=on enables asynchronous teardown (Linux only)\n"
5192    "                chroot=dir chroot to dir just before starting the VM\n"
5193    "                user=username switch to the specified user before starting the VM\n"
5194    "                user=uid:gid ditto, but use specified user-ID and group-ID instead\n",
5195    QEMU_ARCH_ALL)
5196SRST
5197``-run-with [async-teardown=on|off][,chroot=dir][user=username|uid:gid]``
5198    Set QEMU process lifecycle options.
5199
5200    ``async-teardown=on`` enables asynchronous teardown. A new process called
5201    "cleanup/<QEMU_PID>" will be created at startup sharing the address
5202    space with the main QEMU process, using clone. It will wait for the
5203    main QEMU process to terminate completely, and then exit. This allows
5204    QEMU to terminate very quickly even if the guest was huge, leaving the
5205    teardown of the address space to the cleanup process. Since the cleanup
5206    process shares the same cgroups as the main QEMU process, accounting is
5207    performed correctly. This only works if the cleanup process is not
5208    forcefully killed with SIGKILL before the main QEMU process has
5209    terminated completely.
5210
5211    ``chroot=dir`` can be used for doing a chroot to the specified directory
5212    immediately before starting the guest execution. This is especially useful
5213    in combination with -runas.
5214
5215    ``user=username`` or ``user=uid:gid`` can be used to drop root privileges
5216    before starting guest execution. QEMU will use the ``setuid`` and ``setgid``
5217    system calls to switch to the specified identity.  Note that the
5218    ``user=username`` syntax will also apply the full set of supplementary
5219    groups for the user, whereas the ``user=uid:gid`` will use only the
5220    ``gid`` group.
5221ERST
5222#endif
5223
5224DEF("msg", HAS_ARG, QEMU_OPTION_msg,
5225    "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
5226    "                control error message format\n"
5227    "                timestamp=on enables timestamps (default: off)\n"
5228    "                guest-name=on enables guest name prefix but only if\n"
5229    "                              -name guest option is set (default: off)\n",
5230    QEMU_ARCH_ALL)
5231SRST
5232``-msg [timestamp[=on|off]][,guest-name[=on|off]]``
5233    Control error message format.
5234
5235    ``timestamp=on|off``
5236        Prefix messages with a timestamp. Default is off.
5237
5238    ``guest-name=on|off``
5239        Prefix messages with guest name but only if -name guest option is set
5240        otherwise the option is ignored. Default is off.
5241ERST
5242
5243DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
5244    "-dump-vmstate <file>\n"
5245    "                Output vmstate information in JSON format to file.\n"
5246    "                Use the scripts/vmstate-static-checker.py file to\n"
5247    "                check for possible regressions in migration code\n"
5248    "                by comparing two such vmstate dumps.\n",
5249    QEMU_ARCH_ALL)
5250SRST
5251``-dump-vmstate file``
5252    Dump json-encoded vmstate information for current machine type to
5253    file in file
5254ERST
5255
5256DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
5257    "-enable-sync-profile\n"
5258    "                enable synchronization profiling\n",
5259    QEMU_ARCH_ALL)
5260SRST
5261``-enable-sync-profile``
5262    Enable synchronization profiling.
5263ERST
5264
5265#if defined(CONFIG_TCG) && defined(CONFIG_LINUX)
5266DEF("perfmap", 0, QEMU_OPTION_perfmap,
5267    "-perfmap        generate a /tmp/perf-${pid}.map file for perf\n",
5268    QEMU_ARCH_ALL)
5269SRST
5270``-perfmap``
5271    Generate a map file for Linux perf tools that will allow basic profiling
5272    information to be broken down into basic blocks.
5273ERST
5274
5275DEF("jitdump", 0, QEMU_OPTION_jitdump,
5276    "-jitdump        generate a jit-${pid}.dump file for perf\n",
5277    QEMU_ARCH_ALL)
5278SRST
5279``-jitdump``
5280    Generate a dump file for Linux perf tools that maps basic blocks to symbol
5281    names, line numbers and JITted code.
5282ERST
5283#endif
5284
5285DEFHEADING()
5286
5287DEFHEADING(Generic object creation:)
5288
5289DEF("object", HAS_ARG, QEMU_OPTION_object,
5290    "-object TYPENAME[,PROP1=VALUE1,...]\n"
5291    "                create a new object of type TYPENAME setting properties\n"
5292    "                in the order they are specified.  Note that the 'id'\n"
5293    "                property must be set.  These objects are placed in the\n"
5294    "                '/objects' path.\n",
5295    QEMU_ARCH_ALL)
5296SRST
5297``-object typename[,prop1=value1,...]``
5298    Create a new object of type typename setting properties in the order
5299    they are specified. Note that the 'id' property must be set. These
5300    objects are placed in the '/objects' path.
5301
5302    ``-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,offset=offset,readonly=on|off,rom=on|off|auto``
5303        Creates a memory file backend object, which can be used to back
5304        the guest RAM with huge pages.
5305
5306        The ``id`` parameter is a unique ID that will be used to
5307        reference this memory region in other parameters, e.g. ``-numa``,
5308        ``-device nvdimm``, etc.
5309
5310        The ``size`` option provides the size of the memory region, and
5311        accepts common suffixes, e.g. ``500M``.
5312
5313        The ``mem-path`` provides the path to either a shared memory or
5314        huge page filesystem mount.
5315
5316        The ``share`` boolean option determines whether the memory
5317        region is marked as private to QEMU, or shared. The latter
5318        allows a co-operating external process to access the QEMU memory
5319        region.
5320
5321        Setting share=on might affect the ability to configure NUMA
5322        bindings for the memory backend under some circumstances, see
5323        Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
5324        source tree for additional details.
5325
5326        Setting the ``discard-data`` boolean option to on indicates that
5327        file contents can be destroyed when QEMU exits, to avoid
5328        unnecessarily flushing data to the backing file. Note that
5329        ``discard-data`` is only an optimization, and QEMU might not
5330        discard file contents if it aborts unexpectedly or is terminated
5331        using SIGKILL.
5332
5333        The ``merge`` boolean option enables memory merge, also known as
5334        MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
5335        the pages for memory deduplication.
5336
5337        Setting the ``dump`` boolean option to off excludes the memory
5338        from core dumps. This feature is also known as MADV\_DONTDUMP.
5339
5340        The ``prealloc`` boolean option enables memory preallocation.
5341
5342        The ``host-nodes`` option binds the memory range to a list of
5343        NUMA host nodes.
5344
5345        The ``policy`` option sets the NUMA policy to one of the
5346        following values:
5347
5348        ``default``
5349            default host policy
5350
5351        ``preferred``
5352            prefer the given host node list for allocation
5353
5354        ``bind``
5355            restrict memory allocation to the given host node list
5356
5357        ``interleave``
5358            interleave memory allocations across the given host node
5359            list
5360
5361        The ``align`` option specifies the base address alignment when
5362        QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
5363        ``2M``. Some backend store specified by ``mem-path`` requires an
5364        alignment different than the default one used by QEMU, eg the
5365        device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
5366        such cases, users can specify the required alignment via this
5367        option.
5368
5369        The ``offset`` option specifies the offset into the target file
5370        that the region starts at. You can use this parameter to back
5371        multiple regions with a single file.
5372
5373        The ``pmem`` option specifies whether the backing file specified
5374        by ``mem-path`` is in host persistent memory that can be
5375        accessed using the SNIA NVM programming model (e.g. Intel
5376        NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary
5377        operations to guarantee the persistence of its own writes to
5378        ``mem-path`` (e.g. in vNVDIMM label emulation and live
5379        migration). Also, we will map the backend-file with MAP\_SYNC
5380        flag, which ensures the file metadata is in sync for
5381        ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
5382        requires support from both the host kernel (since Linux kernel
5383        4.15) and the filesystem of ``mem-path`` mounted with DAX
5384        option.
5385
5386        The ``readonly`` option specifies whether the backing file is opened
5387        read-only or read-write (default).
5388
5389        The ``rom`` option specifies whether to create Read Only Memory
5390        (ROM) that cannot be modified by the VM. Any write attempts to such
5391        ROM will be denied. Most use cases want proper RAM instead of ROM.
5392        However, selected use cases, like R/O NVDIMMs, can benefit from
5393        ROM. If set to ``on``, create ROM; if set to ``off``, create
5394        writable RAM; if set to ``auto`` (default), the value of the
5395        ``readonly`` option is used. This option is primarily helpful when
5396        we want to have writable RAM in configurations that would
5397        traditionally create ROM before the ``rom`` option was introduced:
5398        VM templating, where we want to open a file readonly
5399        (``readonly=on``) and mark the memory to be private for QEMU
5400        (``share=off``). For this use case, we need writable RAM instead
5401        of ROM, and want to also set ``rom=off``.
5402
5403    ``-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``
5404        Creates a memory backend object, which can be used to back the
5405        guest RAM. Memory backend objects offer more control than the
5406        ``-m`` option that is traditionally used to define guest RAM.
5407        Please refer to ``memory-backend-file`` for a description of the
5408        options.
5409
5410    ``-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``
5411        Creates an anonymous memory file backend object, which allows
5412        QEMU to share the memory with an external process (e.g. when
5413        using vhost-user). The memory is allocated with memfd and
5414        optional sealing. (Linux only)
5415
5416        The ``seal`` option creates a sealed-file, that will block
5417        further resizing the memory ('on' by default).
5418
5419        The ``hugetlb`` option specify the file to be created resides in
5420        the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
5421        with the ``hugetlb`` option, the ``hugetlbsize`` option specify
5422        the hugetlb page size on systems that support multiple hugetlb
5423        page sizes (it must be a power of 2 value supported by the
5424        system).
5425
5426        In some versions of Linux, the ``hugetlb`` option is
5427        incompatible with the ``seal`` option (requires at least Linux
5428        4.16).
5429
5430        Please refer to ``memory-backend-file`` for a description of the
5431        other options.
5432
5433        The ``share`` boolean option is on by default with memfd.
5434
5435    ``-object memory-backend-shm,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``
5436        Creates a POSIX shared memory backend object, which allows
5437        QEMU to share the memory with an external process (e.g. when
5438        using vhost-user).
5439
5440        ``memory-backend-shm`` is a more portable and less featureful version
5441        of ``memory-backend-memfd``. It can then be used in any POSIX system,
5442        especially when memfd is not supported.
5443
5444        Please refer to ``memory-backend-file`` for a description of the
5445        options.
5446
5447        The ``share`` boolean option is on by default with shm. Setting it to
5448        off will cause a failure during allocation because it is not supported
5449        by this backend.
5450
5451    ``-object iommufd,id=id[,fd=fd]``
5452        Creates an iommufd backend which allows control of DMA mapping
5453        through the ``/dev/iommu`` device.
5454
5455        The ``id`` parameter is a unique ID which frontends (such as
5456        vfio-pci of vdpa) will use to connect with the iommufd backend.
5457
5458        The ``fd`` parameter is an optional pre-opened file descriptor
5459        resulting from ``/dev/iommu`` opening. Usually the iommufd is shared
5460        across all subsystems, bringing the benefit of centralized
5461        reference counting.
5462
5463    ``-object rng-builtin,id=id``
5464        Creates a random number generator backend which obtains entropy
5465        from QEMU builtin functions. The ``id`` parameter is a unique ID
5466        that will be used to reference this entropy backend from the
5467        ``virtio-rng`` device. By default, the ``virtio-rng`` device
5468        uses this RNG backend.
5469
5470    ``-object rng-random,id=id,filename=/dev/random``
5471        Creates a random number generator backend which obtains entropy
5472        from a device on the host. The ``id`` parameter is a unique ID
5473        that will be used to reference this entropy backend from the
5474        ``virtio-rng`` device. The ``filename`` parameter specifies
5475        which file to obtain entropy from and if omitted defaults to
5476        ``/dev/urandom``.
5477
5478    ``-object rng-egd,id=id,chardev=chardevid``
5479        Creates a random number generator backend which obtains entropy
5480        from an external daemon running on the host. The ``id``
5481        parameter is a unique ID that will be used to reference this
5482        entropy backend from the ``virtio-rng`` device. The ``chardev``
5483        parameter is the unique ID of a character device backend that
5484        provides the connection to the RNG daemon.
5485
5486    ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
5487        Creates a TLS anonymous credentials object, which can be used to
5488        provide TLS support on network backends. The ``id`` parameter is
5489        a unique ID which network backends will use to access the
5490        credentials. The ``endpoint`` is either ``server`` or ``client``
5491        depending on whether the QEMU network backend that uses the
5492        credentials will be acting as a client or as a server. If
5493        ``verify-peer`` is enabled (the default) then once the handshake
5494        is completed, the peer credentials will be verified, though this
5495        is a no-op for anonymous credentials.
5496
5497        The dir parameter tells QEMU where to find the credential files.
5498        For server endpoints, this directory may contain a file
5499        dh-params.pem providing diffie-hellman parameters to use for the
5500        TLS server. If the file is missing, QEMU will generate a set of
5501        DH parameters at startup. This is a computationally expensive
5502        operation that consumes random pool entropy, so it is
5503        recommended that a persistent set of parameters be generated
5504        upfront and saved.
5505
5506    ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
5507        Creates a TLS Pre-Shared Keys (PSK) credentials object, which
5508        can be used to provide TLS support on network backends. The
5509        ``id`` parameter is a unique ID which network backends will use
5510        to access the credentials. The ``endpoint`` is either ``server``
5511        or ``client`` depending on whether the QEMU network backend that
5512        uses the credentials will be acting as a client or as a server.
5513        For clients only, ``username`` is the username which will be
5514        sent to the server. If omitted it defaults to "qemu".
5515
5516        The dir parameter tells QEMU where to find the keys file. It is
5517        called "dir/keys.psk" and contains "username:key" pairs. This
5518        file can most easily be created using the GnuTLS ``psktool``
5519        program.
5520
5521        For server endpoints, dir may also contain a file dh-params.pem
5522        providing diffie-hellman parameters to use for the TLS server.
5523        If the file is missing, QEMU will generate a set of DH
5524        parameters at startup. This is a computationally expensive
5525        operation that consumes random pool entropy, so it is
5526        recommended that a persistent set of parameters be generated up
5527        front and saved.
5528
5529    ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
5530        Creates a TLS anonymous credentials object, which can be used to
5531        provide TLS support on network backends. The ``id`` parameter is
5532        a unique ID which network backends will use to access the
5533        credentials. The ``endpoint`` is either ``server`` or ``client``
5534        depending on whether the QEMU network backend that uses the
5535        credentials will be acting as a client or as a server. If
5536        ``verify-peer`` is enabled (the default) then once the handshake
5537        is completed, the peer credentials will be verified. With x509
5538        certificates, this implies that the clients must be provided
5539        with valid client certificates too.
5540
5541        The dir parameter tells QEMU where to find the credential files.
5542        For server endpoints, this directory may contain a file
5543        dh-params.pem providing diffie-hellman parameters to use for the
5544        TLS server. If the file is missing, QEMU will generate a set of
5545        DH parameters at startup. This is a computationally expensive
5546        operation that consumes random pool entropy, so it is
5547        recommended that a persistent set of parameters be generated
5548        upfront and saved.
5549
5550        For x509 certificate credentials the directory will contain
5551        further files providing the x509 certificates. The certificates
5552        must be stored in PEM format, in filenames ca-cert.pem,
5553        ca-crl.pem (optional), server-cert.pem (only servers),
5554        server-key.pem (only servers), client-cert.pem (only clients),
5555        and client-key.pem (only clients).
5556
5557        For the server-key.pem and client-key.pem files which contain
5558        sensitive private keys, it is possible to use an encrypted
5559        version by providing the passwordid parameter. This provides the
5560        ID of a previously created ``secret`` object containing the
5561        password for decryption.
5562
5563        The priority parameter allows to override the global default
5564        priority used by gnutls. This can be useful if the system
5565        administrator needs to use a weaker set of crypto priorities for
5566        QEMU without potentially forcing the weakness onto all
5567        applications. Or conversely if one wants wants a stronger
5568        default for QEMU than for all other applications, they can do
5569        this through this parameter. Its format is a gnutls priority
5570        string as described at
5571        https://gnutls.org/manual/html_node/Priority-Strings.html.
5572
5573    ``-object tls-cipher-suites,id=id,priority=priority``
5574        Creates a TLS cipher suites object, which can be used to control
5575        the TLS cipher/protocol algorithms that applications are permitted
5576        to use.
5577
5578        The ``id`` parameter is a unique ID which frontends will use to
5579        access the ordered list of permitted TLS cipher suites from the
5580        host.
5581
5582        The ``priority`` parameter allows to override the global default
5583        priority used by gnutls. This can be useful if the system
5584        administrator needs to use a weaker set of crypto priorities for
5585        QEMU without potentially forcing the weakness onto all
5586        applications. Or conversely if one wants wants a stronger
5587        default for QEMU than for all other applications, they can do
5588        this through this parameter. Its format is a gnutls priority
5589        string as described at
5590        https://gnutls.org/manual/html_node/Priority-Strings.html.
5591
5592        An example of use of this object is to control UEFI HTTPS Boot.
5593        The tls-cipher-suites object exposes the ordered list of permitted
5594        TLS cipher suites from the host side to the guest firmware, via
5595        fw_cfg. The list is represented as an array of IANA_TLS_CIPHER
5596        objects. The firmware uses the IANA_TLS_CIPHER array for configuring
5597        guest-side TLS.
5598
5599        In the following example, the priority at which the host-side policy
5600        is retrieved is given by the ``priority`` property.
5601        Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to
5602        refer to /etc/crypto-policies/back-ends/gnutls.config.
5603
5604        .. parsed-literal::
5605
5606             # |qemu_system| \\
5607                 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\
5608                 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0
5609
5610    ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
5611        Interval t can't be 0, this filter batches the packet delivery:
5612        all packets arriving in a given interval on netdev netdevid are
5613        delayed until the end of the interval. Interval is in
5614        microseconds. ``status`` is optional that indicate whether the
5615        netfilter is on (enabled) or off (disabled), the default status
5616        for netfilter will be 'on'.
5617
5618        queue all\|rx\|tx is an option that can be applied to any
5619        netfilter.
5620
5621        ``all``: the filter is attached both to the receive and the
5622        transmit queue of the netdev (default).
5623
5624        ``rx``: the filter is attached to the receive queue of the
5625        netdev, where it will receive packets sent to the netdev.
5626
5627        ``tx``: the filter is attached to the transmit queue of the
5628        netdev, where it will receive packets sent by the netdev.
5629
5630        position head\|tail\|id=<id> is an option to specify where the
5631        filter should be inserted in the filter list. It can be applied
5632        to any netfilter.
5633
5634        ``head``: the filter is inserted at the head of the filter list,
5635        before any existing filters.
5636
5637        ``tail``: the filter is inserted at the tail of the filter list,
5638        behind any existing filters (default).
5639
5640        ``id=<id>``: the filter is inserted before or behind the filter
5641        specified by <id>, see the insert option below.
5642
5643        insert behind\|before is an option to specify where to insert
5644        the new filter relative to the one specified with
5645        position=id=<id>. It can be applied to any netfilter.
5646
5647        ``before``: insert before the specified filter.
5648
5649        ``behind``: insert behind the specified filter (default).
5650
5651    ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
5652        filter-mirror on netdev netdevid,mirror net packet to
5653        chardevchardevid, if it has the vnet\_hdr\_support flag,
5654        filter-mirror will mirror packet with vnet\_hdr\_len.
5655
5656    ``-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]``
5657        filter-redirector on netdev netdevid,redirect filter's net
5658        packet to chardev chardevid,and redirect indev's packet to
5659        filter.if it has the vnet\_hdr\_support flag, filter-redirector
5660        will redirect packet with vnet\_hdr\_len. Create a
5661        filter-redirector we need to differ outdev id from indev id, id
5662        can not be the same. we can just use indev or outdev, but at
5663        least one of indev or outdev need to be specified.
5664
5665    ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
5666        Filter-rewriter is a part of COLO project.It will rewrite tcp
5667        packet to secondary from primary to keep secondary tcp
5668        connection,and rewrite tcp packet to primary from secondary make
5669        tcp packet can be handled by client.if it has the
5670        vnet\_hdr\_support flag, we can parse packet with vnet header.
5671
5672        usage: colo secondary: -object
5673        filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object
5674        filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object
5675        filter-rewriter,id=rew0,netdev=hn0,queue=all
5676
5677    ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]``
5678        Dump the network traffic on netdev dev to the file specified by
5679        filename. At most len bytes (64k by default) per packet are
5680        stored. The file format is libpcap, so it can be analyzed with
5681        tools such as tcpdump or Wireshark.
5682
5683    ``-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}]``
5684        Colo-compare gets packet from primary\_in chardevid and
5685        secondary\_in, then compare whether the payload of primary packet
5686        and secondary packet are the same. If same, it will output
5687        primary packet to out\_dev, else it will notify COLO-framework to do
5688        checkpoint and send primary packet to out\_dev. In order to
5689        improve efficiency, we need to put the task of comparison in
5690        another iothread. If it has the vnet\_hdr\_support flag,
5691        colo compare will send/recv packet with vnet\_hdr\_len.
5692        The compare\_timeout=@var{ms} determines the maximum time of the
5693        colo-compare hold the packet. The expired\_scan\_cycle=@var{ms}
5694        is to set the period of scanning expired primary node network packets.
5695        The max\_queue\_size=@var{size} is to set the max compare queue
5696        size depend on user environment.
5697        If user want to use Xen COLO, need to add the notify\_dev to
5698        notify Xen colo-frame to do checkpoint.
5699
5700        COLO-compare must be used with the help of filter-mirror,
5701        filter-redirector and filter-rewriter.
5702
5703        ::
5704
5705            KVM COLO
5706
5707            primary:
5708            -netdev tap,id=hn0,vhost=off
5709            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
5710            -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off
5711            -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off
5712            -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off
5713            -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
5714            -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off
5715            -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
5716            -object iothread,id=iothread1
5717            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
5718            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
5719            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
5720            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
5721
5722            secondary:
5723            -netdev tap,id=hn0,vhost=off
5724            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5725            -chardev socket,id=red0,host=3.3.3.3,port=9003
5726            -chardev socket,id=red1,host=3.3.3.3,port=9004
5727            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5728            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5729
5730
5731            Xen COLO
5732
5733            primary:
5734            -netdev tap,id=hn0,vhost=off
5735            -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
5736            -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off
5737            -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off
5738            -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off
5739            -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
5740            -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off
5741            -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
5742            -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server=on,wait=off
5743            -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
5744            -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
5745            -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
5746            -object iothread,id=iothread1
5747            -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=notify_way,iothread=iothread1
5748
5749            secondary:
5750            -netdev tap,id=hn0,vhost=off
5751            -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5752            -chardev socket,id=red0,host=3.3.3.3,port=9003
5753            -chardev socket,id=red1,host=3.3.3.3,port=9004
5754            -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5755            -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5756
5757        If you want to know the detail of above command line, you can
5758        read the colo-compare git log.
5759
5760    ``-object cryptodev-backend-builtin,id=id[,queues=queues]``
5761        Creates a cryptodev backend which executes crypto operations from
5762        the QEMU cipher APIs. The id parameter is a unique ID that will
5763        be used to reference this cryptodev backend from the
5764        ``virtio-crypto`` device. The queues parameter is optional,
5765        which specify the queue number of cryptodev backend, the default
5766        of queues is 1.
5767
5768        .. parsed-literal::
5769
5770             # |qemu_system| \\
5771               [...] \\
5772                   -object cryptodev-backend-builtin,id=cryptodev0 \\
5773                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5774               [...]
5775
5776    ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]``
5777        Creates a vhost-user cryptodev backend, backed by a chardev
5778        chardevid. The id parameter is a unique ID that will be used to
5779        reference this cryptodev backend from the ``virtio-crypto``
5780        device. The chardev should be a unix domain socket backed one.
5781        The vhost-user uses a specifically defined protocol to pass
5782        vhost ioctl replacement messages to an application on the other
5783        end of the socket. The queues parameter is optional, which
5784        specify the queue number of cryptodev backend for multiqueue
5785        vhost-user, the default of queues is 1.
5786
5787        .. parsed-literal::
5788
5789             # |qemu_system| \\
5790               [...] \\
5791                   -chardev socket,id=chardev0,path=/path/to/socket \\
5792                   -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\
5793                   -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5794               [...]
5795
5796    ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]``
5797      \
5798    ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]``
5799        Defines a secret to store a password, encryption key, or some
5800        other sensitive data. The sensitive data can either be passed
5801        directly via the data parameter, or indirectly via the file
5802        parameter. Using the data parameter is insecure unless the
5803        sensitive data is encrypted.
5804
5805        The sensitive data can be provided in raw format (the default),
5806        or base64. When encoded as JSON, the raw format only supports
5807        valid UTF-8 characters, so base64 is recommended for sending
5808        binary data. QEMU will convert from which ever format is
5809        provided to the format it needs internally. eg, an RBD password
5810        can be provided in raw format, even though it will be base64
5811        encoded when passed onto the RBD sever.
5812
5813        For added protection, it is possible to encrypt the data
5814        associated with a secret using the AES-256-CBC cipher. Use of
5815        encryption is indicated by providing the keyid and iv
5816        parameters. The keyid parameter provides the ID of a previously
5817        defined secret that contains the AES-256 decryption key. This
5818        key should be 32-bytes long and be base64 encoded. The iv
5819        parameter provides the random initialization vector used for
5820        encryption of this particular secret and should be a base64
5821        encrypted string of the 16-byte IV.
5822
5823        The simplest (insecure) usage is to provide the secret inline
5824
5825        .. parsed-literal::
5826
5827             # |qemu_system| -object secret,id=sec0,data=letmein,format=raw
5828
5829        The simplest secure usage is to provide the secret via a file
5830
5831        # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object
5832        secret,id=sec0,file=mypasswd.txt,format=raw
5833
5834        For greater security, AES-256-CBC should be used. To illustrate
5835        usage, consider the openssl command line tool which can encrypt
5836        the data. Note that when encrypting, the plaintext must be
5837        padded to the cipher block size (32 bytes) using the standard
5838        PKCS#5/6 compatible padding algorithm.
5839
5840        First a master key needs to be created in base64 encoding:
5841
5842        ::
5843
5844             # openssl rand -base64 32 > key.b64
5845             # KEY=$(base64 -d key.b64 | hexdump  -v -e '/1 "%02X"')
5846
5847        Each secret to be encrypted needs to have a random
5848        initialization vector generated. These do not need to be kept
5849        secret
5850
5851        ::
5852
5853             # openssl rand -base64 16 > iv.b64
5854             # IV=$(base64 -d iv.b64 | hexdump  -v -e '/1 "%02X"')
5855
5856        The secret to be defined can now be encrypted, in this case
5857        we're telling openssl to base64 encode the result, but it could
5858        be left as raw bytes if desired.
5859
5860        ::
5861
5862             # SECRET=$(printf "letmein" |
5863                        openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
5864
5865        When launching QEMU, create a master secret pointing to
5866        ``key.b64`` and specify that to be used to decrypt the user
5867        password. Pass the contents of ``iv.b64`` to the second secret
5868
5869        .. parsed-literal::
5870
5871             # |qemu_system| \\
5872                 -object secret,id=secmaster0,format=base64,file=key.b64 \\
5873                 -object secret,id=sec0,keyid=secmaster0,format=base64,\\
5874                     data=$SECRET,iv=$(<iv.b64)
5875
5876    ``-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]``
5877        Create a Secure Encrypted Virtualization (SEV) guest object,
5878        which can be used to provide the guest memory encryption support
5879        on AMD processors.
5880
5881        When memory encryption is enabled, one of the physical address
5882        bit (aka the C-bit) is utilized to mark if a memory page is
5883        protected. The ``cbitpos`` is used to provide the C-bit
5884        position. The C-bit position is Host family dependent hence user
5885        must provide this value. On EPYC, the value should be 47.
5886
5887        When memory encryption is enabled, we loose certain bits in
5888        physical address space. The ``reduced-phys-bits`` is used to
5889        provide the number of bits we loose in physical address space.
5890        Similar to C-bit, the value is Host family dependent. On EPYC,
5891        a guest will lose a maximum of 1 bit, so the value should be 1.
5892
5893        The ``sev-device`` provides the device file to use for
5894        communicating with the SEV firmware running inside AMD Secure
5895        Processor. The default device is '/dev/sev'. If hardware
5896        supports memory encryption then /dev/sev devices are created by
5897        CCP driver.
5898
5899        The ``policy`` provides the guest policy to be enforced by the
5900        SEV firmware and restrict what configuration and operational
5901        commands can be performed on this guest by the hypervisor. The
5902        policy should be provided by the guest owner and is bound to the
5903        guest and cannot be changed throughout the lifetime of the
5904        guest. The default is 0.
5905
5906        If guest ``policy`` allows sharing the key with another SEV
5907        guest then ``handle`` can be use to provide handle of the guest
5908        from which to share the key.
5909
5910        The ``dh-cert-file`` and ``session-file`` provides the guest
5911        owner's Public Diffie-Hillman key defined in SEV spec. The PDH
5912        and session parameters are used for establishing a cryptographic
5913        session with the guest owner to negotiate keys used for
5914        attestation. The file must be encoded in base64.
5915
5916        The ``kernel-hashes`` adds the hashes of given kernel/initrd/
5917        cmdline to a designated guest firmware page for measured Linux
5918        boot with -kernel. The default is off. (Since 6.2)
5919
5920        e.g to launch a SEV guest
5921
5922        .. parsed-literal::
5923
5924             # |qemu_system_x86| \\
5925                 ...... \\
5926                 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1 \\
5927                 -machine ...,memory-encryption=sev0 \\
5928                 .....
5929
5930    ``-object authz-simple,id=id,identity=string``
5931        Create an authorization object that will control access to
5932        network services.
5933
5934        The ``identity`` parameter is identifies the user and its format
5935        depends on the network service that authorization object is
5936        associated with. For authorizing based on TLS x509 certificates,
5937        the identity must be the x509 distinguished name. Note that care
5938        must be taken to escape any commas in the distinguished name.
5939
5940        An example authorization object to validate a x509 distinguished
5941        name would look like:
5942
5943        .. parsed-literal::
5944
5945             # |qemu_system| \\
5946                 ... \\
5947                 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\
5948                 ...
5949
5950        Note the use of quotes due to the x509 distinguished name
5951        containing whitespace, and escaping of ','.
5952
5953    ``-object authz-listfile,id=id,filename=path,refresh=on|off``
5954        Create an authorization object that will control access to
5955        network services.
5956
5957        The ``filename`` parameter is the fully qualified path to a file
5958        containing the access control list rules in JSON format.
5959
5960        An example set of rules that match against SASL usernames might
5961        look like:
5962
5963        ::
5964
5965              {
5966                "rules": [
5967                   { "match": "fred", "policy": "allow", "format": "exact" },
5968                   { "match": "bob", "policy": "allow", "format": "exact" },
5969                   { "match": "danb", "policy": "deny", "format": "glob" },
5970                   { "match": "dan*", "policy": "allow", "format": "exact" },
5971                ],
5972                "policy": "deny"
5973              }
5974
5975        When checking access the object will iterate over all the rules
5976        and the first rule to match will have its ``policy`` value
5977        returned as the result. If no rules match, then the default
5978        ``policy`` value is returned.
5979
5980        The rules can either be an exact string match, or they can use
5981        the simple UNIX glob pattern matching to allow wildcards to be
5982        used.
5983
5984        If ``refresh`` is set to true the file will be monitored and
5985        automatically reloaded whenever its content changes.
5986
5987        As with the ``authz-simple`` object, the format of the identity
5988        strings being matched depends on the network service, but is
5989        usually a TLS x509 distinguished name, or a SASL username.
5990
5991        An example authorization object to validate a SASL username
5992        would look like:
5993
5994        .. parsed-literal::
5995
5996             # |qemu_system| \\
5997                 ... \\
5998                 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\
5999                 ...
6000
6001    ``-object authz-pam,id=id,service=string``
6002        Create an authorization object that will control access to
6003        network services.
6004
6005        The ``service`` parameter provides the name of a PAM service to
6006        use for authorization. It requires that a file
6007        ``/etc/pam.d/service`` exist to provide the configuration for
6008        the ``account`` subsystem.
6009
6010        An example authorization object to validate a TLS x509
6011        distinguished name would look like:
6012
6013        .. parsed-literal::
6014
6015             # |qemu_system| \\
6016                 ... \\
6017                 -object authz-pam,id=auth0,service=qemu-vnc \\
6018                 ...
6019
6020        There would then be a corresponding config file for PAM at
6021        ``/etc/pam.d/qemu-vnc`` that contains:
6022
6023        ::
6024
6025            account requisite  pam_listfile.so item=user sense=allow \
6026                       file=/etc/qemu/vnc.allow
6027
6028        Finally the ``/etc/qemu/vnc.allow`` file would contain the list
6029        of x509 distinguished names that are permitted access
6030
6031        ::
6032
6033            CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
6034
6035    ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch``
6036        Creates a dedicated event loop thread that devices can be
6037        assigned to. This is known as an IOThread. By default device
6038        emulation happens in vCPU threads or the main event loop thread.
6039        This can become a scalability bottleneck. IOThreads allow device
6040        emulation and I/O to run on other host CPUs.
6041
6042        The ``id`` parameter is a unique ID that will be used to
6043        reference this IOThread from ``-device ...,iothread=id``.
6044        Multiple devices can be assigned to an IOThread. Note that not
6045        all devices support an ``iothread`` parameter.
6046
6047        The ``query-iothreads`` QMP command lists IOThreads and reports
6048        their thread IDs so that the user can configure host CPU
6049        pinning/affinity.
6050
6051        IOThreads use an adaptive polling algorithm to reduce event loop
6052        latency. Instead of entering a blocking system call to monitor
6053        file descriptors and then pay the cost of being woken up when an
6054        event occurs, the polling algorithm spins waiting for events for
6055        a short time. The algorithm's default parameters are suitable
6056        for many cases but can be adjusted based on knowledge of the
6057        workload and/or host device latency.
6058
6059        The ``poll-max-ns`` parameter is the maximum number of
6060        nanoseconds to busy wait for events. Polling can be disabled by
6061        setting this value to 0.
6062
6063        The ``poll-grow`` parameter is the multiplier used to increase
6064        the polling time when the algorithm detects it is missing events
6065        due to not polling long enough.
6066
6067        The ``poll-shrink`` parameter is the divisor used to decrease
6068        the polling time when the algorithm detects it is spending too
6069        long polling without encountering events.
6070
6071        The ``aio-max-batch`` parameter is the maximum number of requests
6072        in a batch for the AIO engine, 0 means that the engine will use
6073        its default.
6074
6075        The IOThread parameters can be modified at run-time using the
6076        ``qom-set`` command (where ``iothread1`` is the IOThread's
6077        ``id``):
6078
6079        ::
6080
6081            (qemu) qom-set /objects/iothread1 poll-max-ns 100000
6082ERST
6083
6084
6085HXCOMM This is the last statement. Insert new options before this line!
6086
6087#undef DEF
6088#undef DEFHEADING
6089#undef ARCHHEADING
6090