qapi: Fix malformed "Since:" section tags (again)
[qemu/armbru.git] / qemu-options.hx
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1 HXCOMM See docs/devel/docs.rst for the format of this file.
2 HXCOMM
3 HXCOMM Use DEFHEADING() to define headings in both help text and rST.
4 HXCOMM Text between SRST and ERST is copied to the rST version and
5 HXCOMM discarded from C version.
6 HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to
7 HXCOMM construct option structures, enums and help message for specified
8 HXCOMM architectures.
9 HXCOMM HXCOMM can be used for comments, discarded from both rST and C.
11 DEFHEADING(Standard options:)
13 DEF("help", 0, QEMU_OPTION_h,
14 "-h or -help display this help and exit\n", QEMU_ARCH_ALL)
15 SRST
16 ``-h``
17 Display help and exit
18 ERST
20 DEF("version", 0, QEMU_OPTION_version,
21 "-version display version information and exit\n", QEMU_ARCH_ALL)
22 SRST
23 ``-version``
24 Display version information and exit
25 ERST
27 DEF("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)
44 SRST
45 ``-machine [type=]name[,prop=value[,...]]``
46 Select the emulated machine by name. Use ``-machine help`` to list
47 available machines.
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.
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.
60 Supported machine properties are:
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.
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. For accel=xen the default is
72 off otherwise the default is on.
74 ``dump-guest-core=on|off``
75 Include guest memory in a core dump. The default is on.
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).
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.
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.
94 ``nvdimm=on|off``
95 Enables or disables NVDIMM support. The default is off.
97 ``memory-encryption=``
98 Memory encryption object to use. The default is none.
100 ``hmat=on|off``
101 Enables or disables ACPI Heterogeneous Memory Attribute Table
102 (HMAT) support. The default is off.
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.
108 For example:
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
115 Migration compatibility note:
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.
124 For example:
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
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).
134 Described in the CXL 2.0 ECN: CEDT CFMWS & QTG _DSM.
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.
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.
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.
153 ``interleave-granularity=granularity`` sets the granularity of
154 interleave. Default 256KiB. Only 256KiB, 512KiB, 1024KiB, 2048KiB
155 4096KiB, 8192KiB and 16384KiB granularities supported.
157 Example:
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=512k
162 ERST
164 DEF("M", HAS_ARG, QEMU_OPTION_M,
165 " sgx-epc.0.memdev=memid,sgx-epc.0.node=numaid\n",
166 QEMU_ARCH_ALL)
168 SRST
169 ``sgx-epc.0.memdev=@var{memid},sgx-epc.0.node=@var{numaid}``
170 Define an SGX EPC section.
171 ERST
173 DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
174 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
175 SRST
176 ``-cpu model``
177 Select CPU model (``-cpu help`` for list and additional feature
178 selection)
179 ERST
181 DEF("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)
195 SRST
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.
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)
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.
215 ``kvm-shadow-mem=size``
216 Defines the size of the KVM shadow MMU.
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.
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.
230 ``tb-size=n``
231 Controls the size (in MiB) of the TCG translation block cache.
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).
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.
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).
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.
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``.
280 ERST
282 DEF("smp", HAS_ARG, QEMU_OPTION_smp,
283 "-smp [[cpus=]n][,maxcpus=maxcpus][,drawers=drawers][,books=books][,sockets=sockets]\n"
284 " [,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]\n"
285 " set the number of initial CPUs to 'n' [default=1]\n"
286 " maxcpus= maximum number of total CPUs, including\n"
287 " offline CPUs for hotplug, etc\n"
288 " drawers= number of drawers on the machine board\n"
289 " books= number of books in one drawer\n"
290 " sockets= number of sockets in one book\n"
291 " dies= number of dies in one socket\n"
292 " clusters= number of clusters in one die\n"
293 " cores= number of cores in one cluster\n"
294 " threads= number of threads in one core\n"
295 "Note: Different machines may have different subsets of the CPU topology\n"
296 " parameters supported, so the actual meaning of the supported parameters\n"
297 " will vary accordingly. For example, for a machine type that supports a\n"
298 " three-level CPU hierarchy of sockets/cores/threads, the parameters will\n"
299 " sequentially mean as below:\n"
300 " sockets means the number of sockets on the machine board\n"
301 " cores means the number of cores in one socket\n"
302 " threads means the number of threads in one core\n"
303 " For a particular machine type board, an expected CPU topology hierarchy\n"
304 " can be defined through the supported sub-option. Unsupported parameters\n"
305 " can also be provided in addition to the sub-option, but their values\n"
306 " must be set as 1 in the purpose of correct parsing.\n",
307 QEMU_ARCH_ALL)
308 SRST
309 ``-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]``
310 Simulate a SMP system with '\ ``n``\ ' CPUs initially present on
311 the machine type board. On boards supporting CPU hotplug, the optional
312 '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be
313 added at runtime. When both parameters are omitted, the maximum number
314 of CPUs will be calculated from the provided topology members and the
315 initial CPU count will match the maximum number. When only one of them
316 is given then the omitted one will be set to its counterpart's value.
317 Both parameters may be specified, but the maximum number of CPUs must
318 be equal to or greater than the initial CPU count. Product of the
319 CPU topology hierarchy must be equal to the maximum number of CPUs.
320 Both parameters are subject to an upper limit that is determined by
321 the specific machine type chosen.
323 To control reporting of CPU topology information, values of the topology
324 parameters can be specified. Machines may only support a subset of the
325 parameters and different machines may have different subsets supported
326 which vary depending on capacity of the corresponding CPU targets. So
327 for a particular machine type board, an expected topology hierarchy can
328 be defined through the supported sub-option. Unsupported parameters can
329 also be provided in addition to the sub-option, but their values must be
330 set as 1 in the purpose of correct parsing.
332 Either the initial CPU count, or at least one of the topology parameters
333 must be specified. The specified parameters must be greater than zero,
334 explicit configuration like "cpus=0" is not allowed. Values for any
335 omitted parameters will be computed from those which are given.
337 For example, the following sub-option defines a CPU topology hierarchy
338 (2 sockets totally on the machine, 2 cores per socket, 2 threads per
339 core) for a machine that only supports sockets/cores/threads.
340 Some members of the option can be omitted but their values will be
341 automatically computed:
345 -smp 8,sockets=2,cores=2,threads=2,maxcpus=8
347 The following sub-option defines a CPU topology hierarchy (2 sockets
348 totally on the machine, 2 dies per socket, 2 cores per die, 2 threads
349 per core) for PC machines which support sockets/dies/cores/threads.
350 Some members of the option can be omitted but their values will be
351 automatically computed:
355 -smp 16,sockets=2,dies=2,cores=2,threads=2,maxcpus=16
357 The following sub-option defines a CPU topology hierarchy (2 sockets
358 totally on the machine, 2 clusters per socket, 2 cores per cluster,
359 2 threads per core) for ARM virt machines which support sockets/clusters
360 /cores/threads. Some members of the option can be omitted but their values
361 will be automatically computed:
365 -smp 16,sockets=2,clusters=2,cores=2,threads=2,maxcpus=16
367 Historically preference was given to the coarsest topology parameters
368 when computing missing values (ie sockets preferred over cores, which
369 were preferred over threads), however, this behaviour is considered
370 liable to change. Prior to 6.2 the preference was sockets over cores
371 over threads. Since 6.2 the preference is cores over sockets over threads.
373 For example, the following option defines a machine board with 2 sockets
374 of 1 core before 6.2 and 1 socket of 2 cores after 6.2:
378 -smp 2
380 Note: The cluster topology will only be generated in ACPI and exposed
381 to guest if it's explicitly specified in -smp.
382 ERST
384 DEF("numa", HAS_ARG, QEMU_OPTION_numa,
385 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
386 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
387 "-numa dist,src=source,dst=destination,val=distance\n"
388 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
389 "-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"
390 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
391 QEMU_ARCH_ALL)
392 SRST
393 ``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
395 ``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
397 ``-numa dist,src=source,dst=destination,val=distance``
399 ``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]``
401 ``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=type[,latency=lat][,bandwidth=bw]``
403 ``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]``
404 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA
405 distance from a source node to a destination node. Set the ACPI
406 Heterogeneous Memory Attributes for the given nodes.
408 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and
409 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a
410 contiguous range of CPU indexes (or a single VCPU if lastcpu is
411 omitted). A non-contiguous set of VCPUs can be represented by
412 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is
413 omitted on all nodes, VCPUs are automatically split between them.
415 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a
416 NUMA node:
420 -numa node,cpus=0-2,cpus=5
422 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option
423 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to
424 assign CPU objects to a node using topology layout properties of
425 CPU. The set of properties is machine specific, and depends on used
426 machine type/'\ ``smp``\ ' options. It could be queried with
427 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ '
428 property specifies node to which CPU object will be assigned, it's
429 required for node to be declared with '\ ``node``\ ' option before
430 it's used with '\ ``cpu``\ ' option.
432 For example:
436 -M pc \
437 -smp 1,sockets=2,maxcpus=2 \
438 -numa node,nodeid=0 -numa node,nodeid=1 \
439 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
441 '\ ``memdev``\ ' option assigns RAM from a given memory backend
442 device to a node. It is recommended to use '\ ``memdev``\ ' option
443 over legacy '\ ``mem``\ ' option. This is because '\ ``memdev``\ '
444 option provides better performance and more control over the
445 backend's RAM (e.g. '\ ``prealloc``\ ' parameter of
446 '\ ``-memory-backend-ram``\ ' allows memory preallocation).
448 For compatibility reasons, legacy '\ ``mem``\ ' option is
449 supported in 5.0 and older machine types. Note that '\ ``mem``\ '
450 and '\ ``memdev``\ ' are mutually exclusive. If one node uses
451 '\ ``memdev``\ ', the rest nodes have to use '\ ``memdev``\ '
452 option, and vice versa.
454 Users must specify memory for all NUMA nodes by '\ ``memdev``\ '
455 (or legacy '\ ``mem``\ ' if available). In QEMU 5.2, the support
456 for '\ ``-numa node``\ ' without memory specified was removed.
458 '\ ``initiator``\ ' is an additional option that points to an
459 initiator NUMA node that has best performance (the lowest latency or
460 largest bandwidth) to this NUMA node. Note that this option can be
461 set only when the machine property 'hmat' is set to 'on'.
463 Following example creates a machine with 2 NUMA nodes, node 0 has
464 CPU. node 1 has only memory, and its initiator is node 0. Note that
465 because node 0 has CPU, by default the initiator of node 0 is itself
466 and must be itself.
470 -machine hmat=on \
471 -m 2G,slots=2,maxmem=4G \
472 -object memory-backend-ram,size=1G,id=m0 \
473 -object memory-backend-ram,size=1G,id=m1 \
474 -numa node,nodeid=0,memdev=m0 \
475 -numa node,nodeid=1,memdev=m1,initiator=0 \
476 -smp 2,sockets=2,maxcpus=2 \
477 -numa cpu,node-id=0,socket-id=0 \
478 -numa cpu,node-id=0,socket-id=1
480 source and destination are NUMA node IDs. distance is the NUMA
481 distance from source to destination. The distance from a node to
482 itself is always 10. If any pair of nodes is given a distance, then
483 all pairs must be given distances. Although, when distances are only
484 given in one direction for each pair of nodes, then the distances in
485 the opposite directions are assumed to be the same. If, however, an
486 asymmetrical pair of distances is given for even one node pair, then
487 all node pairs must be provided distance values for both directions,
488 even when they are symmetrical. When a node is unreachable from
489 another node, set the pair's distance to 255.
491 Note that the -``numa`` option doesn't allocate any of the specified
492 resources, it just assigns existing resources to NUMA nodes. This
493 means that one still has to use the ``-m``, ``-smp`` options to
494 allocate RAM and VCPUs respectively.
496 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
497 Information between initiator and target NUMA nodes in ACPI
498 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can
499 create memory requests, usually it has one or more processors.
500 Target NUMA node contains addressable memory.
502 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is
503 the memory hierarchy of the target NUMA node: if hierarchy is
504 'memory', the structure represents the memory performance; if
505 hierarchy is 'first-level\|second-level\|third-level', this
506 structure represents aggregated performance of memory side caches
507 for each domain. type of 'data-type' is type of data represented by
508 this structure instance: if 'hierarchy' is 'memory', 'data-type' is
509 'access\|read\|write' latency or 'access\|read\|write' bandwidth of
510 the target memory; if 'hierarchy' is
511 'first-level\|second-level\|third-level', 'data-type' is
512 'access\|read\|write' hit latency or 'access\|read\|write' hit
513 bandwidth of the target memory side cache.
515 lat is latency value in nanoseconds. bw is bandwidth value, the
516 possible value and units are NUM[M\|G\|T], mean that the bandwidth
517 value are NUM byte per second (or MB/s, GB/s or TB/s depending on
518 used suffix). Note that if latency or bandwidth value is 0, means
519 the corresponding latency or bandwidth information is not provided.
521 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory
522 belongs. size is the size of memory side cache in bytes. level is
523 the cache level described in this structure, note that the cache
524 level 0 should not be used with '\ ``hmat-cache``\ ' option.
525 associativity is the cache associativity, the possible value is
526 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
527 is the write policy. line is the cache Line size in bytes.
529 For example, the following options describe 2 NUMA nodes. Node 0 has
530 2 cpus and a ram, node 1 has only a ram. The processors in node 0
531 access memory in node 0 with access-latency 5 nanoseconds,
532 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access
533 memory in NUMA node 1 with access-latency 10 nanoseconds,
534 access-bandwidth is 100 MB/s. And for memory side cache information,
535 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB,
536 policy is write-back, the cache Line size is 8 bytes:
540 -machine hmat=on \
541 -m 2G \
542 -object memory-backend-ram,size=1G,id=m0 \
543 -object memory-backend-ram,size=1G,id=m1 \
544 -smp 2,sockets=2,maxcpus=2 \
545 -numa node,nodeid=0,memdev=m0 \
546 -numa node,nodeid=1,memdev=m1,initiator=0 \
547 -numa cpu,node-id=0,socket-id=0 \
548 -numa cpu,node-id=0,socket-id=1 \
549 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
550 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
551 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
552 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
553 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
554 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
555 ERST
557 DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
558 "-add-fd fd=fd,set=set[,opaque=opaque]\n"
559 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
560 SRST
561 ``-add-fd fd=fd,set=set[,opaque=opaque]``
562 Add a file descriptor to an fd set. Valid options are:
564 ``fd=fd``
565 This option defines the file descriptor of which a duplicate is
566 added to fd set. The file descriptor cannot be stdin, stdout, or
567 stderr.
569 ``set=set``
570 This option defines the ID of the fd set to add the file
571 descriptor to.
573 ``opaque=opaque``
574 This option defines a free-form string that can be used to
575 describe fd.
577 You can open an image using pre-opened file descriptors from an fd
578 set:
580 .. parsed-literal::
582 |qemu_system| \\
583 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
584 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
585 -drive file=/dev/fdset/2,index=0,media=disk
586 ERST
588 DEF("set", HAS_ARG, QEMU_OPTION_set,
589 "-set group.id.arg=value\n"
590 " set <arg> parameter for item <id> of type <group>\n"
591 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
592 SRST
593 ``-set group.id.arg=value``
594 Set parameter arg for item id of type group
595 ERST
597 DEF("global", HAS_ARG, QEMU_OPTION_global,
598 "-global driver.property=value\n"
599 "-global driver=driver,property=property,value=value\n"
600 " set a global default for a driver property\n",
601 QEMU_ARCH_ALL)
602 SRST
603 ``-global driver.prop=value``
605 ``-global driver=driver,property=property,value=value``
606 Set default value of driver's property prop to value, e.g.:
608 .. parsed-literal::
610 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img
612 In particular, you can use this to set driver properties for devices
613 which are created automatically by the machine model. To create a
614 device which is not created automatically and set properties on it,
615 use -``device``.
617 -global driver.prop=value is shorthand for -global
618 driver=driver,property=prop,value=value. The longhand syntax works
619 even when driver contains a dot.
620 ERST
622 DEF("boot", HAS_ARG, QEMU_OPTION_boot,
623 "-boot [order=drives][,once=drives][,menu=on|off]\n"
624 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
625 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
626 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
627 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n"
628 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
629 QEMU_ARCH_ALL)
630 SRST
631 ``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
632 Specify boot order drives as a string of drive letters. Valid drive
633 letters depend on the target architecture. The x86 PC uses: a, b
634 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
635 (Etherboot from network adapter 1-4), hard disk boot is the default.
636 To apply a particular boot order only on the first startup, specify
637 it via ``once``. Note that the ``order`` or ``once`` parameter
638 should not be used together with the ``bootindex`` property of
639 devices, since the firmware implementations normally do not support
640 both at the same time.
642 Interactive boot menus/prompts can be enabled via ``menu=on`` as far
643 as firmware/BIOS supports them. The default is non-interactive boot.
645 A splash picture could be passed to bios, enabling user to show it
646 as logo, when option splash=sp\_name is given and menu=on, If
647 firmware/BIOS supports them. Currently Seabios for X86 system
648 support it. limitation: The splash file could be a jpeg file or a
649 BMP file in 24 BPP format(true color). The resolution should be
650 supported by the SVGA mode, so the recommended is 320x240, 640x480,
651 800x640.
653 A timeout could be passed to bios, guest will pause for rb\_timeout
654 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
655 not reboot, qemu passes '-1' to bios by default. Currently Seabios
656 for X86 system support it.
658 Do strict boot via ``strict=on`` as far as firmware/BIOS supports
659 it. This only effects when boot priority is changed by bootindex
660 options. The default is non-strict boot.
662 .. parsed-literal::
664 # try to boot from network first, then from hard disk
665 |qemu_system_x86| -boot order=nc
666 # boot from CD-ROM first, switch back to default order after reboot
667 |qemu_system_x86| -boot once=d
668 # boot with a splash picture for 5 seconds.
669 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000
671 Note: The legacy format '-boot drives' is still supported but its
672 use is discouraged as it may be removed from future versions.
673 ERST
675 DEF("m", HAS_ARG, QEMU_OPTION_m,
676 "-m [size=]megs[,slots=n,maxmem=size]\n"
677 " configure guest RAM\n"
678 " size: initial amount of guest memory\n"
679 " slots: number of hotplug slots (default: none)\n"
680 " maxmem: maximum amount of guest memory (default: none)\n"
681 " Note: Some architectures might enforce a specific granularity\n",
682 QEMU_ARCH_ALL)
683 SRST
684 ``-m [size=]megs[,slots=n,maxmem=size]``
685 Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
686 Optionally, a suffix of "M" or "G" can be used to signify a value in
687 megabytes or gigabytes respectively. Optional pair slots, maxmem
688 could be used to set amount of hotpluggable memory slots and maximum
689 amount of memory. Note that maxmem must be aligned to the page size.
691 For example, the following command-line sets the guest startup RAM
692 size to 1GB, creates 3 slots to hotplug additional memory and sets
693 the maximum memory the guest can reach to 4GB:
695 .. parsed-literal::
697 |qemu_system| -m 1G,slots=3,maxmem=4G
699 If slots and maxmem are not specified, memory hotplug won't be
700 enabled and the guest startup RAM will never increase.
701 ERST
703 DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
704 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
705 SRST
706 ``-mem-path path``
707 Allocate guest RAM from a temporarily created file in path.
708 ERST
710 DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
711 "-mem-prealloc preallocate guest memory (use with -mem-path)\n",
712 QEMU_ARCH_ALL)
713 SRST
714 ``-mem-prealloc``
715 Preallocate memory when using -mem-path.
716 ERST
718 DEF("k", HAS_ARG, QEMU_OPTION_k,
719 "-k language use keyboard layout (for example 'fr' for French)\n",
720 QEMU_ARCH_ALL)
721 SRST
722 ``-k language``
723 Use keyboard layout language (for example ``fr`` for French). This
724 option is only needed where it is not easy to get raw PC keycodes
725 (e.g. on Macs, with some X11 servers or with a VNC or curses
726 display). You don't normally need to use it on PC/Linux or
727 PC/Windows hosts.
729 The available layouts are:
733 ar de-ch es fo fr-ca hu ja mk no pt-br sv
734 da en-gb et fr fr-ch is lt nl pl ru th
735 de en-us fi fr-be hr it lv nl-be pt sl tr
737 The default is ``en-us``.
738 ERST
741 DEF("audio", HAS_ARG, QEMU_OPTION_audio,
742 "-audio [driver=]driver[,prop[=value][,...]]\n"
743 " specifies default audio backend when `audiodev` is not\n"
744 " used to create a machine or sound device;"
745 " options are the same as for -audiodev\n"
746 "-audio [driver=]driver,model=value[,prop[=value][,...]]\n"
747 " specifies the audio backend and device to use;\n"
748 " apart from 'model', options are the same as for -audiodev.\n"
749 " use '-audio model=help' to show possible devices.\n",
750 QEMU_ARCH_ALL)
751 SRST
752 ``-audio [driver=]driver[,model=value][,prop[=value][,...]]``
753 If the ``model`` option is specified, ``-audio`` is a shortcut
754 for configuring both the guest audio hardware and the host audio
755 backend in one go. The guest hardware model can be set with
756 ``model=modelname``. Use ``model=help`` to list the available
757 device types.
759 The following two example do exactly the same, to show how ``-audio``
760 can be used to shorten the command line length:
762 .. parsed-literal::
764 |qemu_system| -audiodev pa,id=pa -device sb16,audiodev=pa
765 |qemu_system| -audio pa,model=sb16
767 If the ``model`` option is not specified, ``-audio`` is used to
768 configure a default audio backend that will be used whenever the
769 ``audiodev`` property is not set on a device or machine. In
770 particular, ``-audio none`` ensures that no audio is produced even
771 for machines that have embedded sound hardware.
773 In both cases, the driver option is the same as with the corresponding
774 ``-audiodev`` option below. Use ``driver=help`` to list the available
775 drivers.
777 ERST
779 DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
780 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
781 " specifies the audio backend to use\n"
782 " Use ``-audiodev help`` to list the available drivers\n"
783 " id= identifier of the backend\n"
784 " timer-period= timer period in microseconds\n"
785 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
786 " in|out.fixed-settings= use fixed settings for host audio\n"
787 " in|out.frequency= frequency to use with fixed settings\n"
788 " in|out.channels= number of channels to use with fixed settings\n"
789 " in|out.format= sample format to use with fixed settings\n"
790 " valid values: s8, s16, s32, u8, u16, u32, f32\n"
791 " in|out.voices= number of voices to use\n"
792 " in|out.buffer-length= length of buffer in microseconds\n"
793 "-audiodev none,id=id,[,prop[=value][,...]]\n"
794 " dummy driver that discards all output\n"
795 #ifdef CONFIG_AUDIO_ALSA
796 "-audiodev alsa,id=id[,prop[=value][,...]]\n"
797 " in|out.dev= name of the audio device to use\n"
798 " in|out.period-length= length of period in microseconds\n"
799 " in|out.try-poll= attempt to use poll mode\n"
800 " threshold= threshold (in microseconds) when playback starts\n"
801 #endif
802 #ifdef CONFIG_AUDIO_COREAUDIO
803 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
804 " in|out.buffer-count= number of buffers\n"
805 #endif
806 #ifdef CONFIG_AUDIO_DSOUND
807 "-audiodev dsound,id=id[,prop[=value][,...]]\n"
808 " latency= add extra latency to playback in microseconds\n"
809 #endif
810 #ifdef CONFIG_AUDIO_OSS
811 "-audiodev oss,id=id[,prop[=value][,...]]\n"
812 " in|out.dev= path of the audio device to use\n"
813 " in|out.buffer-count= number of buffers\n"
814 " in|out.try-poll= attempt to use poll mode\n"
815 " try-mmap= try using memory mapped access\n"
816 " exclusive= open device in exclusive mode\n"
817 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
818 #endif
819 #ifdef CONFIG_AUDIO_PA
820 "-audiodev pa,id=id[,prop[=value][,...]]\n"
821 " server= PulseAudio server address\n"
822 " in|out.name= source/sink device name\n"
823 " in|out.latency= desired latency in microseconds\n"
824 #endif
825 #ifdef CONFIG_AUDIO_PIPEWIRE
826 "-audiodev pipewire,id=id[,prop[=value][,...]]\n"
827 " in|out.name= source/sink device name\n"
828 " in|out.stream-name= name of pipewire stream\n"
829 " in|out.latency= desired latency in microseconds\n"
830 #endif
831 #ifdef CONFIG_AUDIO_SDL
832 "-audiodev sdl,id=id[,prop[=value][,...]]\n"
833 " in|out.buffer-count= number of buffers\n"
834 #endif
835 #ifdef CONFIG_AUDIO_SNDIO
836 "-audiodev sndio,id=id[,prop[=value][,...]]\n"
837 #endif
838 #ifdef CONFIG_SPICE
839 "-audiodev spice,id=id[,prop[=value][,...]]\n"
840 #endif
841 #ifdef CONFIG_DBUS_DISPLAY
842 "-audiodev dbus,id=id[,prop[=value][,...]]\n"
843 #endif
844 "-audiodev wav,id=id[,prop[=value][,...]]\n"
845 " path= path of wav file to record\n",
846 QEMU_ARCH_ALL)
847 SRST
848 ``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
849 Adds a new audio backend driver identified by id. There are global
850 and driver specific properties. Some values can be set differently
851 for input and output, they're marked with ``in|out.``. You can set
852 the input's property with ``in.prop`` and the output's property with
853 ``out.prop``. For example:
857 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
858 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
860 NOTE: parameter validation is known to be incomplete, in many cases
861 specifying an invalid option causes QEMU to print an error message
862 and continue emulation without sound.
864 Valid global options are:
866 ``id=identifier``
867 Identifies the audio backend.
869 ``timer-period=period``
870 Sets the timer period used by the audio subsystem in
871 microseconds. Default is 10000 (10 ms).
873 ``in|out.mixing-engine=on|off``
874 Use QEMU's mixing engine to mix all streams inside QEMU and
875 convert audio formats when not supported by the backend. When
876 off, fixed-settings must be off too. Note that disabling this
877 option means that the selected backend must support multiple
878 streams and the audio formats used by the virtual cards,
879 otherwise you'll get no sound. It's not recommended to disable
880 this option unless you want to use 5.1 or 7.1 audio, as mixing
881 engine only supports mono and stereo audio. Default is on.
883 ``in|out.fixed-settings=on|off``
884 Use fixed settings for host audio. When off, it will change
885 based on how the guest opens the sound card. In this case you
886 must not specify frequency, channels or format. Default is on.
888 ``in|out.frequency=frequency``
889 Specify the frequency to use when using fixed-settings. Default
890 is 44100Hz.
892 ``in|out.channels=channels``
893 Specify the number of channels to use when using fixed-settings.
894 Default is 2 (stereo).
896 ``in|out.format=format``
897 Specify the sample format to use when using fixed-settings.
898 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
899 ``u32``, ``f32``. Default is ``s16``.
901 ``in|out.voices=voices``
902 Specify the number of voices to use. Default is 1.
904 ``in|out.buffer-length=usecs``
905 Sets the size of the buffer in microseconds.
907 ``-audiodev none,id=id[,prop[=value][,...]]``
908 Creates a dummy backend that discards all outputs. This backend has
909 no backend specific properties.
911 ``-audiodev alsa,id=id[,prop[=value][,...]]``
912 Creates backend using the ALSA. This backend is only available on
913 Linux.
915 ALSA specific options are:
917 ``in|out.dev=device``
918 Specify the ALSA device to use for input and/or output. Default
919 is ``default``.
921 ``in|out.period-length=usecs``
922 Sets the period length in microseconds.
924 ``in|out.try-poll=on|off``
925 Attempt to use poll mode with the device. Default is on.
927 ``threshold=threshold``
928 Threshold (in microseconds) when playback starts. Default is 0.
930 ``-audiodev coreaudio,id=id[,prop[=value][,...]]``
931 Creates a backend using Apple's Core Audio. This backend is only
932 available on Mac OS and only supports playback.
934 Core Audio specific options are:
936 ``in|out.buffer-count=count``
937 Sets the count of the buffers.
939 ``-audiodev dsound,id=id[,prop[=value][,...]]``
940 Creates a backend using Microsoft's DirectSound. This backend is
941 only available on Windows and only supports playback.
943 DirectSound specific options are:
945 ``latency=usecs``
946 Add extra usecs microseconds latency to playback. Default is
947 10000 (10 ms).
949 ``-audiodev oss,id=id[,prop[=value][,...]]``
950 Creates a backend using OSS. This backend is available on most
951 Unix-like systems.
953 OSS specific options are:
955 ``in|out.dev=device``
956 Specify the file name of the OSS device to use. Default is
957 ``/dev/dsp``.
959 ``in|out.buffer-count=count``
960 Sets the count of the buffers.
962 ``in|out.try-poll=on|of``
963 Attempt to use poll mode with the device. Default is on.
965 ``try-mmap=on|off``
966 Try using memory mapped device access. Default is off.
968 ``exclusive=on|off``
969 Open the device in exclusive mode (vmix won't work in this
970 case). Default is off.
972 ``dsp-policy=policy``
973 Sets the timing policy (between 0 and 10, where smaller number
974 means smaller latency but higher CPU usage). Use -1 to use
975 buffer sizes specified by ``buffer`` and ``buffer-count``. This
976 option is ignored if you do not have OSS 4. Default is 5.
978 ``-audiodev pa,id=id[,prop[=value][,...]]``
979 Creates a backend using PulseAudio. This backend is available on
980 most systems.
982 PulseAudio specific options are:
984 ``server=server``
985 Sets the PulseAudio server to connect to.
987 ``in|out.name=sink``
988 Use the specified source/sink for recording/playback.
990 ``in|out.latency=usecs``
991 Desired latency in microseconds. The PulseAudio server will try
992 to honor this value but actual latencies may be lower or higher.
994 ``-audiodev pipewire,id=id[,prop[=value][,...]]``
995 Creates a backend using PipeWire. This backend is available on
996 most systems.
998 PipeWire specific options are:
1000 ``in|out.latency=usecs``
1001 Desired latency in microseconds.
1003 ``in|out.name=sink``
1004 Use the specified source/sink for recording/playback.
1006 ``in|out.stream-name``
1007 Specify the name of pipewire stream.
1009 ``-audiodev sdl,id=id[,prop[=value][,...]]``
1010 Creates a backend using SDL. This backend is available on most
1011 systems, but you should use your platform's native backend if
1012 possible.
1014 SDL specific options are:
1016 ``in|out.buffer-count=count``
1017 Sets the count of the buffers.
1019 ``-audiodev sndio,id=id[,prop[=value][,...]]``
1020 Creates a backend using SNDIO. This backend is available on
1021 OpenBSD and most other Unix-like systems.
1023 Sndio specific options are:
1025 ``in|out.dev=device``
1026 Specify the sndio device to use for input and/or output. Default
1027 is ``default``.
1029 ``in|out.latency=usecs``
1030 Sets the desired period length in microseconds.
1032 ``-audiodev spice,id=id[,prop[=value][,...]]``
1033 Creates a backend that sends audio through SPICE. This backend
1034 requires ``-spice`` and automatically selected in that case, so
1035 usually you can ignore this option. This backend has no backend
1036 specific properties.
1038 ``-audiodev wav,id=id[,prop[=value][,...]]``
1039 Creates a backend that writes audio to a WAV file.
1041 Backend specific options are:
1043 ``path=path``
1044 Write recorded audio into the specified file. Default is
1045 ``qemu.wav``.
1046 ERST
1048 DEF("device", HAS_ARG, QEMU_OPTION_device,
1049 "-device driver[,prop[=value][,...]]\n"
1050 " add device (based on driver)\n"
1051 " prop=value,... sets driver properties\n"
1052 " use '-device help' to print all possible drivers\n"
1053 " use '-device driver,help' to print all possible properties\n",
1054 QEMU_ARCH_ALL)
1055 SRST
1056 ``-device driver[,prop[=value][,...]]``
1057 Add device driver. prop=value sets driver properties. Valid
1058 properties depend on the driver. To get help on possible drivers and
1059 properties, use ``-device help`` and ``-device driver,help``.
1061 Some drivers are:
1063 ``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]``
1064 Add an IPMI BMC. This is a simulation of a hardware management
1065 interface processor that normally sits on a system. It provides a
1066 watchdog and the ability to reset and power control the system. You
1067 need to connect this to an IPMI interface to make it useful
1069 The IPMI slave address to use for the BMC. The default is 0x20. This
1070 address is the BMC's address on the I2C network of management
1071 controllers. If you don't know what this means, it is safe to ignore
1074 ``id=id``
1075 The BMC id for interfaces to use this device.
1077 ``slave_addr=val``
1078 Define slave address to use for the BMC. The default is 0x20.
1080 ``sdrfile=file``
1081 file containing raw Sensor Data Records (SDR) data. The default
1082 is none.
1084 ``fruareasize=val``
1085 size of a Field Replaceable Unit (FRU) area. The default is
1086 1024.
1088 ``frudatafile=file``
1089 file containing raw Field Replaceable Unit (FRU) inventory data.
1090 The default is none.
1092 ``guid=uuid``
1093 value for the GUID for the BMC, in standard UUID format. If this
1094 is set, get "Get GUID" command to the BMC will return it.
1095 Otherwise "Get GUID" will return an error.
1097 ``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
1098 Add a connection to an external IPMI BMC simulator. Instead of
1099 locally emulating the BMC like the above item, instead connect to an
1100 external entity that provides the IPMI services.
1102 A connection is made to an external BMC simulator. If you do this,
1103 it is strongly recommended that you use the "reconnect=" chardev
1104 option to reconnect to the simulator if the connection is lost. Note
1105 that if this is not used carefully, it can be a security issue, as
1106 the interface has the ability to send resets, NMIs, and power off
1107 the VM. It's best if QEMU makes a connection to an external
1108 simulator running on a secure port on localhost, so neither the
1109 simulator nor QEMU is exposed to any outside network.
1111 See the "lanserv/README.vm" file in the OpenIPMI library for more
1112 details on the external interface.
1114 ``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
1115 Add a KCS IPMI interface on the ISA bus. This also adds a
1116 corresponding ACPI and SMBIOS entries, if appropriate.
1118 ``bmc=id``
1119 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
1120 above.
1122 ``ioport=val``
1123 Define the I/O address of the interface. The default is 0xca0
1124 for KCS.
1126 ``irq=val``
1127 Define the interrupt to use. The default is 5. To disable
1128 interrupts, set this to 0.
1130 ``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
1131 Like the KCS interface, but defines a BT interface. The default port
1132 is 0xe4 and the default interrupt is 5.
1134 ``-device pci-ipmi-kcs,bmc=id``
1135 Add a KCS IPMI interface on the PCI bus.
1137 ``bmc=id``
1138 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
1140 ``-device pci-ipmi-bt,bmc=id``
1141 Like the KCS interface, but defines a BT interface on the PCI bus.
1143 ``-device intel-iommu[,option=...]``
1144 This is only supported by ``-machine q35``, which will enable Intel VT-d
1145 emulation within the guest. It supports below options:
1147 ``intremap=on|off`` (default: auto)
1148 This enables interrupt remapping feature. It's required to enable
1149 complete x2apic. Currently it only supports kvm kernel-irqchip modes
1150 ``off`` or ``split``, while full kernel-irqchip is not yet supported.
1151 The default value is "auto", which will be decided by the mode of
1152 kernel-irqchip.
1154 ``caching-mode=on|off`` (default: off)
1155 This enables caching mode for the VT-d emulated device. When
1156 caching-mode is enabled, each guest DMA buffer mapping will generate an
1157 IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in
1158 a synchronous way. It is required for ``-device vfio-pci`` to work
1159 with the VT-d device, because host assigned devices requires to setup
1160 the DMA mapping on the host before guest DMA starts.
1162 ``device-iotlb=on|off`` (default: off)
1163 This enables device-iotlb capability for the emulated VT-d device. So
1164 far virtio/vhost should be the only real user for this parameter,
1165 paired with ats=on configured for the device.
1167 ``aw-bits=39|48`` (default: 39)
1168 This decides the address width of IOVA address space. The address
1169 space has 39 bits width for 3-level IOMMU page tables, and 48 bits for
1170 4-level IOMMU page tables.
1172 Please also refer to the wiki page for general scenarios of VT-d
1173 emulation in QEMU: https://wiki.qemu.org/Features/VT-d.
1175 ERST
1177 DEF("name", HAS_ARG, QEMU_OPTION_name,
1178 "-name string1[,process=string2][,debug-threads=on|off]\n"
1179 " set the name of the guest\n"
1180 " string1 sets the window title and string2 the process name\n"
1181 " When debug-threads is enabled, individual threads are given a separate name\n"
1182 " NOTE: The thread names are for debugging and not a stable API.\n",
1183 QEMU_ARCH_ALL)
1184 SRST
1185 ``-name name``
1186 Sets the name of the guest. This name will be displayed in the SDL
1187 window caption. The name will also be used for the VNC server. Also
1188 optionally set the top visible process name in Linux. Naming of
1189 individual threads can also be enabled on Linux to aid debugging.
1190 ERST
1192 DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
1193 "-uuid %08x-%04x-%04x-%04x-%012x\n"
1194 " specify machine UUID\n", QEMU_ARCH_ALL)
1195 SRST
1196 ``-uuid uuid``
1197 Set system UUID.
1198 ERST
1200 DEFHEADING()
1202 DEFHEADING(Block device options:)
1204 SRST
1205 The QEMU block device handling options have a long history and
1206 have gone through several iterations as the feature set and complexity
1207 of the block layer have grown. Many online guides to QEMU often
1208 reference older and deprecated options, which can lead to confusion.
1210 The most explicit way to describe disks is to use a combination of
1211 ``-device`` to specify the hardware device and ``-blockdev`` to
1212 describe the backend. The device defines what the guest sees and the
1213 backend describes how QEMU handles the data. It is the only guaranteed
1214 stable interface for describing block devices and as such is
1215 recommended for management tools and scripting.
1217 The ``-drive`` option combines the device and backend into a single
1218 command line option which is a more human friendly. There is however no
1219 interface stability guarantee although some older board models still
1220 need updating to work with the modern blockdev forms.
1222 Older options like ``-hda`` are essentially macros which expand into
1223 ``-drive`` options for various drive interfaces. The original forms
1224 bake in a lot of assumptions from the days when QEMU was emulating a
1225 legacy PC, they are not recommended for modern configurations.
1227 ERST
1229 DEF("fda", HAS_ARG, QEMU_OPTION_fda,
1230 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
1231 DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
1232 SRST
1233 ``-fda file``
1235 ``-fdb file``
1236 Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in
1237 the System Emulation Users Guide).
1238 ERST
1240 DEF("hda", HAS_ARG, QEMU_OPTION_hda,
1241 "-hda/-hdb file use 'file' as hard disk 0/1 image\n", QEMU_ARCH_ALL)
1242 DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
1243 DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
1244 "-hdc/-hdd file use 'file' as hard disk 2/3 image\n", QEMU_ARCH_ALL)
1245 DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
1246 SRST
1247 ``-hda file``
1249 ``-hdb file``
1251 ``-hdc file``
1253 ``-hdd file``
1254 Use file as hard disk 0, 1, 2 or 3 image on the default bus of the
1255 emulated machine (this is for example the IDE bus on most x86 machines,
1256 but it can also be SCSI, virtio or something else on other target
1257 architectures). See also the :ref:`disk images` chapter in the System
1258 Emulation Users Guide.
1259 ERST
1261 DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
1262 "-cdrom file use 'file' as CD-ROM image\n",
1263 QEMU_ARCH_ALL)
1264 SRST
1265 ``-cdrom file``
1266 Use file as CD-ROM image on the default bus of the emulated machine
1267 (which is IDE1 master on x86, so you cannot use ``-hdc`` and ``-cdrom``
1268 at the same time there). On systems that support it, you can use the
1269 host CD-ROM by using ``/dev/cdrom`` as filename.
1270 ERST
1272 DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
1273 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
1274 " [,cache.direct=on|off][,cache.no-flush=on|off]\n"
1275 " [,read-only=on|off][,auto-read-only=on|off]\n"
1276 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
1277 " [,driver specific parameters...]\n"
1278 " configure a block backend\n", QEMU_ARCH_ALL)
1279 SRST
1280 ``-blockdev option[,option[,option[,...]]]``
1281 Define a new block driver node. Some of the options apply to all
1282 block drivers, other options are only accepted for a specific block
1283 driver. See below for a list of generic options and options for the
1284 most common block drivers.
1286 Options that expect a reference to another node (e.g. ``file``) can
1287 be given in two ways. Either you specify the node name of an already
1288 existing node (file=node-name), or you define a new node inline,
1289 adding options for the referenced node after a dot
1290 (file.filename=path,file.aio=native).
1292 A block driver node created with ``-blockdev`` can be used for a
1293 guest device by specifying its node name for the ``drive`` property
1294 in a ``-device`` argument that defines a block device.
1296 ``Valid options for any block driver node:``
1297 ``driver``
1298 Specifies the block driver to use for the given node.
1300 ``node-name``
1301 This defines the name of the block driver node by which it
1302 will be referenced later. The name must be unique, i.e. it
1303 must not match the name of a different block driver node, or
1304 (if you use ``-drive`` as well) the ID of a drive.
1306 If no node name is specified, it is automatically generated.
1307 The generated node name is not intended to be predictable
1308 and changes between QEMU invocations. For the top level, an
1309 explicit node name must be specified.
1311 ``read-only``
1312 Open the node read-only. Guest write attempts will fail.
1314 Note that some block drivers support only read-only access,
1315 either generally or in certain configurations. In this case,
1316 the default value ``read-only=off`` does not work and the
1317 option must be specified explicitly.
1319 ``auto-read-only``
1320 If ``auto-read-only=on`` is set, QEMU may fall back to
1321 read-only usage even when ``read-only=off`` is requested, or
1322 even switch between modes as needed, e.g. depending on
1323 whether the image file is writable or whether a writing user
1324 is attached to the node.
1326 ``force-share``
1327 Override the image locking system of QEMU by forcing the
1328 node to utilize weaker shared access for permissions where
1329 it would normally request exclusive access. When there is
1330 the potential for multiple instances to have the same file
1331 open (whether this invocation of QEMU is the first or the
1332 second instance), both instances must permit shared access
1333 for the second instance to succeed at opening the file.
1335 Enabling ``force-share=on`` requires ``read-only=on``.
1337 ``cache.direct``
1338 The host page cache can be avoided with ``cache.direct=on``.
1339 This will attempt to do disk IO directly to the guest's
1340 memory. QEMU may still perform an internal copy of the data.
1342 ``cache.no-flush``
1343 In case you don't care about data integrity over host
1344 failures, you can use ``cache.no-flush=on``. This option
1345 tells QEMU that it never needs to write any data to the disk
1346 but can instead keep things in cache. If anything goes
1347 wrong, like your host losing power, the disk storage getting
1348 disconnected accidentally, etc. your image will most
1349 probably be rendered unusable.
1351 ``discard=discard``
1352 discard is one of "ignore" (or "off") or "unmap" (or "on")
1353 and controls whether ``discard`` (also known as ``trim`` or
1354 ``unmap``) requests are ignored or passed to the filesystem.
1355 Some machine types may not support discard requests.
1357 ``detect-zeroes=detect-zeroes``
1358 detect-zeroes is "off", "on" or "unmap" and enables the
1359 automatic conversion of plain zero writes by the OS to
1360 driver specific optimized zero write commands. You may even
1361 choose "unmap" if discard is set to "unmap" to allow a zero
1362 write to be converted to an ``unmap`` operation.
1364 ``Driver-specific options for file``
1365 This is the protocol-level block driver for accessing regular
1366 files.
1368 ``filename``
1369 The path to the image file in the local filesystem
1371 ``aio``
1372 Specifies the AIO backend (threads/native/io_uring,
1373 default: threads)
1375 ``locking``
1376 Specifies whether the image file is protected with Linux OFD
1377 / POSIX locks. The default is to use the Linux Open File
1378 Descriptor API if available, otherwise no lock is applied.
1379 (auto/on/off, default: auto)
1381 Example:
1385 -blockdev driver=file,node-name=disk,filename=disk.img
1387 ``Driver-specific options for raw``
1388 This is the image format block driver for raw images. It is
1389 usually stacked on top of a protocol level block driver such as
1390 ``file``.
1392 ``file``
1393 Reference to or definition of the data source block driver
1394 node (e.g. a ``file`` driver node)
1396 Example 1:
1400 -blockdev driver=file,node-name=disk_file,filename=disk.img
1401 -blockdev driver=raw,node-name=disk,file=disk_file
1403 Example 2:
1407 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1409 ``Driver-specific options for qcow2``
1410 This is the image format block driver for qcow2 images. It is
1411 usually stacked on top of a protocol level block driver such as
1412 ``file``.
1414 ``file``
1415 Reference to or definition of the data source block driver
1416 node (e.g. a ``file`` driver node)
1418 ``backing``
1419 Reference to or definition of the backing file block device
1420 (default is taken from the image file). It is allowed to
1421 pass ``null`` here in order to disable the default backing
1422 file.
1424 ``lazy-refcounts``
1425 Whether to enable the lazy refcounts feature (on/off;
1426 default is taken from the image file)
1428 ``cache-size``
1429 The maximum total size of the L2 table and refcount block
1430 caches in bytes (default: the sum of l2-cache-size and
1431 refcount-cache-size)
1433 ``l2-cache-size``
1434 The maximum size of the L2 table cache in bytes (default: if
1435 cache-size is not specified - 32M on Linux platforms, and 8M
1436 on non-Linux platforms; otherwise, as large as possible
1437 within the cache-size, while permitting the requested or the
1438 minimal refcount cache size)
1440 ``refcount-cache-size``
1441 The maximum size of the refcount block cache in bytes
1442 (default: 4 times the cluster size; or if cache-size is
1443 specified, the part of it which is not used for the L2
1444 cache)
1446 ``cache-clean-interval``
1447 Clean unused entries in the L2 and refcount caches. The
1448 interval is in seconds. The default value is 600 on
1449 supporting platforms, and 0 on other platforms. Setting it
1450 to 0 disables this feature.
1452 ``pass-discard-request``
1453 Whether discard requests to the qcow2 device should be
1454 forwarded to the data source (on/off; default: on if
1455 discard=unmap is specified, off otherwise)
1457 ``pass-discard-snapshot``
1458 Whether discard requests for the data source should be
1459 issued when a snapshot operation (e.g. deleting a snapshot)
1460 frees clusters in the qcow2 file (on/off; default: on)
1462 ``pass-discard-other``
1463 Whether discard requests for the data source should be
1464 issued on other occasions where a cluster gets freed
1465 (on/off; default: off)
1467 ``discard-no-unref``
1468 When enabled, data clusters will remain preallocated when they are
1469 no longer used, e.g. because they are discarded or converted to
1470 zero clusters. As usual, whether the old data is discarded or kept
1471 on the protocol level (i.e. in the image file) depends on the
1472 setting of the pass-discard-request option. Keeping the clusters
1473 preallocated prevents qcow2 fragmentation that would otherwise be
1474 caused by freeing and re-allocating them later. Besides potential
1475 performance degradation, such fragmentation can lead to increased
1476 allocation of clusters past the end of the image file,
1477 resulting in image files whose file length can grow much larger
1478 than their guest disk size would suggest.
1479 If image file length is of concern (e.g. when storing qcow2
1480 images directly on block devices), you should consider enabling
1481 this option.
1483 ``overlap-check``
1484 Which overlap checks to perform for writes to the image
1485 (none/constant/cached/all; default: cached). For details or
1486 finer granularity control refer to the QAPI documentation of
1487 ``blockdev-add``.
1489 Example 1:
1493 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1494 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1496 Example 2:
1500 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1502 ``Driver-specific options for other drivers``
1503 Please refer to the QAPI documentation of the ``blockdev-add``
1504 QMP command.
1505 ERST
1507 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1508 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1509 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1510 " [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1511 " [,werror=ignore|stop|report|enospc][,id=name]\n"
1512 " [,aio=threads|native|io_uring]\n"
1513 " [,readonly=on|off][,copy-on-read=on|off]\n"
1514 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1515 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1516 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1517 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1518 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1519 " [[,iops_size=is]]\n"
1520 " [[,group=g]]\n"
1521 " use 'file' as a drive image\n", QEMU_ARCH_ALL)
1522 SRST
1523 ``-drive option[,option[,option[,...]]]``
1524 Define a new drive. This includes creating a block driver node (the
1525 backend) as well as a guest device, and is mostly a shortcut for
1526 defining the corresponding ``-blockdev`` and ``-device`` options.
1528 ``-drive`` accepts all options that are accepted by ``-blockdev``.
1529 In addition, it knows the following options:
1531 ``file=file``
1532 This option defines which disk image (see the :ref:`disk images`
1533 chapter in the System Emulation Users Guide) to use with this drive.
1534 If the filename contains comma, you must double it (for instance,
1535 "file=my,,file" to use file "my,file").
1537 Special files such as iSCSI devices can be specified using
1538 protocol specific URLs. See the section for "Device URL Syntax"
1539 for more information.
1541 ``if=interface``
1542 This option defines on which type on interface the drive is
1543 connected. Available types are: ide, scsi, sd, mtd, floppy,
1544 pflash, virtio, none.
1546 ``bus=bus,unit=unit``
1547 These options define where is connected the drive by defining
1548 the bus number and the unit id.
1550 ``index=index``
1551 This option defines where the drive is connected by using an
1552 index in the list of available connectors of a given interface
1553 type.
1555 ``media=media``
1556 This option defines the type of the media: disk or cdrom.
1558 ``snapshot=snapshot``
1559 snapshot is "on" or "off" and controls snapshot mode for the
1560 given drive (see ``-snapshot``).
1562 ``cache=cache``
1563 cache is "none", "writeback", "unsafe", "directsync" or
1564 "writethrough" and controls how the host cache is used to access
1565 block data. This is a shortcut that sets the ``cache.direct``
1566 and ``cache.no-flush`` options (as in ``-blockdev``), and
1567 additionally ``cache.writeback``, which provides a default for
1568 the ``write-cache`` option of block guest devices (as in
1569 ``-device``). The modes correspond to the following settings:
1571 ============= =============== ============ ==============
1572 \ cache.writeback cache.direct cache.no-flush
1573 ============= =============== ============ ==============
1574 writeback on off off
1575 none on on off
1576 writethrough off off off
1577 directsync off on off
1578 unsafe on off on
1579 ============= =============== ============ ==============
1581 The default mode is ``cache=writeback``.
1583 ``aio=aio``
1584 aio is "threads", "native", or "io_uring" and selects between pthread
1585 based disk I/O, native Linux AIO, or Linux io_uring API.
1587 ``format=format``
1588 Specify which disk format will be used rather than detecting the
1589 format. Can be used to specify format=raw to avoid interpreting
1590 an untrusted format header.
1592 ``werror=action,rerror=action``
1593 Specify which action to take on write and read errors. Valid
1594 actions are: "ignore" (ignore the error and try to continue),
1595 "stop" (pause QEMU), "report" (report the error to the guest),
1596 "enospc" (pause QEMU only if the host disk is full; report the
1597 error to the guest otherwise). The default setting is
1598 ``werror=enospc`` and ``rerror=report``.
1600 ``copy-on-read=copy-on-read``
1601 copy-on-read is "on" or "off" and enables whether to copy read
1602 backing file sectors into the image file.
1604 ``bps=b,bps_rd=r,bps_wr=w``
1605 Specify bandwidth throttling limits in bytes per second, either
1606 for all request types or for reads or writes only. Small values
1607 can lead to timeouts or hangs inside the guest. A safe minimum
1608 for disks is 2 MB/s.
1610 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
1611 Specify bursts in bytes per second, either for all request types
1612 or for reads or writes only. Bursts allow the guest I/O to spike
1613 above the limit temporarily.
1615 ``iops=i,iops_rd=r,iops_wr=w``
1616 Specify request rate limits in requests per second, either for
1617 all request types or for reads or writes only.
1619 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
1620 Specify bursts in requests per second, either for all request
1621 types or for reads or writes only. Bursts allow the guest I/O to
1622 spike above the limit temporarily.
1624 ``iops_size=is``
1625 Let every is bytes of a request count as a new request for iops
1626 throttling purposes. Use this option to prevent guests from
1627 circumventing iops limits by sending fewer but larger requests.
1629 ``group=g``
1630 Join a throttling quota group with given name g. All drives that
1631 are members of the same group are accounted for together. Use
1632 this option to prevent guests from circumventing throttling
1633 limits by using many small disks instead of a single larger
1634 disk.
1636 By default, the ``cache.writeback=on`` mode is used. It will report
1637 data writes as completed as soon as the data is present in the host
1638 page cache. This is safe as long as your guest OS makes sure to
1639 correctly flush disk caches where needed. If your guest OS does not
1640 handle volatile disk write caches correctly and your host crashes or
1641 loses power, then the guest may experience data corruption.
1643 For such guests, you should consider using ``cache.writeback=off``.
1644 This means that the host page cache will be used to read and write
1645 data, but write notification will be sent to the guest only after
1646 QEMU has made sure to flush each write to the disk. Be aware that
1647 this has a major impact on performance.
1649 When using the ``-snapshot`` option, unsafe caching is always used.
1651 Copy-on-read avoids accessing the same backing file sectors
1652 repeatedly and is useful when the backing file is over a slow
1653 network. By default copy-on-read is off.
1655 Instead of ``-cdrom`` you can use:
1657 .. parsed-literal::
1659 |qemu_system| -drive file=file,index=2,media=cdrom
1661 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:
1663 .. parsed-literal::
1665 |qemu_system| -drive file=file,index=0,media=disk
1666 |qemu_system| -drive file=file,index=1,media=disk
1667 |qemu_system| -drive file=file,index=2,media=disk
1668 |qemu_system| -drive file=file,index=3,media=disk
1670 You can open an image using pre-opened file descriptors from an fd
1671 set:
1673 .. parsed-literal::
1675 |qemu_system| \\
1676 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
1677 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
1678 -drive file=/dev/fdset/2,index=0,media=disk
1680 You can connect a CDROM to the slave of ide0:
1682 .. parsed-literal::
1684 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom
1686 If you don't specify the "file=" argument, you define an empty
1687 drive:
1689 .. parsed-literal::
1691 |qemu_system_x86| -drive if=ide,index=1,media=cdrom
1693 Instead of ``-fda``, ``-fdb``, you can use:
1695 .. parsed-literal::
1697 |qemu_system_x86| -drive file=file,index=0,if=floppy
1698 |qemu_system_x86| -drive file=file,index=1,if=floppy
1700 By default, interface is "ide" and index is automatically
1701 incremented:
1703 .. parsed-literal::
1705 |qemu_system_x86| -drive file=a -drive file=b
1707 is interpreted like:
1709 .. parsed-literal::
1711 |qemu_system_x86| -hda a -hdb b
1712 ERST
1714 DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1715 "-mtdblock file use 'file' as on-board Flash memory image\n",
1716 QEMU_ARCH_ALL)
1717 SRST
1718 ``-mtdblock file``
1719 Use file as on-board Flash memory image.
1720 ERST
1722 DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1723 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1724 SRST
1725 ``-sd file``
1726 Use file as SecureDigital card image.
1727 ERST
1729 DEF("snapshot", 0, QEMU_OPTION_snapshot,
1730 "-snapshot write to temporary files instead of disk image files\n",
1731 QEMU_ARCH_ALL)
1732 SRST
1733 ``-snapshot``
1734 Write to temporary files instead of disk image files. In this case,
1735 the raw disk image you use is not written back. You can however
1736 force the write back by pressing C-a s (see the :ref:`disk images`
1737 chapter in the System Emulation Users Guide).
1739 .. warning::
1740 snapshot is incompatible with ``-blockdev`` (instead use qemu-img
1741 to manually create snapshot images to attach to your blockdev).
1742 If you have mixed ``-blockdev`` and ``-drive`` declarations you
1743 can use the 'snapshot' property on your drive declarations
1744 instead of this global option.
1746 ERST
1748 DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1749 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1750 " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n"
1751 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1752 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1753 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1754 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1755 " [[,throttling.iops-size=is]]\n"
1756 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n"
1757 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n"
1758 "-fsdev synth,id=id\n",
1759 QEMU_ARCH_ALL)
1761 SRST
1762 ``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]``
1764 ``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]``
1766 ``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]``
1768 ``-fsdev synth,id=id[,readonly=on]``
1769 Define a new file system device. Valid options are:
1771 ``local``
1772 Accesses to the filesystem are done by QEMU.
1774 ``proxy``
1775 Accesses to the filesystem are done by virtfs-proxy-helper(1). This
1776 option is deprecated (since QEMU 8.1) and will be removed in a future
1777 version of QEMU. Use ``local`` instead.
1779 ``synth``
1780 Synthetic filesystem, only used by QTests.
1782 ``id=id``
1783 Specifies identifier for this device.
1785 ``path=path``
1786 Specifies the export path for the file system device. Files
1787 under this path will be available to the 9p client on the guest.
1789 ``security_model=security_model``
1790 Specifies the security model to be used for this export path.
1791 Supported security models are "passthrough", "mapped-xattr",
1792 "mapped-file" and "none". In "passthrough" security model, files
1793 are stored using the same credentials as they are created on the
1794 guest. This requires QEMU to run as root. In "mapped-xattr"
1795 security model, some of the file attributes like uid, gid, mode
1796 bits and link target are stored as file attributes. For
1797 "mapped-file" these attributes are stored in the hidden
1798 .virtfs\_metadata directory. Directories exported by this
1799 security model cannot interact with other unix tools. "none"
1800 security model is same as passthrough except the sever won't
1801 report failures if it fails to set file attributes like
1802 ownership. Security model is mandatory only for local fsdriver.
1803 Other fsdrivers (like proxy) don't take security model as a
1804 parameter.
1806 ``writeout=writeout``
1807 This is an optional argument. The only supported value is
1808 "immediate". This means that host page cache will be used to
1809 read and write data but write notification will be sent to the
1810 guest only when the data has been reported as written by the
1811 storage subsystem.
1813 ``readonly=on``
1814 Enables exporting 9p share as a readonly mount for guests. By
1815 default read-write access is given.
1817 ``socket=socket``
1818 Enables proxy filesystem driver to use passed socket file for
1819 communicating with virtfs-proxy-helper(1).
1821 ``sock_fd=sock_fd``
1822 Enables proxy filesystem driver to use passed socket descriptor
1823 for communicating with virtfs-proxy-helper(1). Usually a helper
1824 like libvirt will create socketpair and pass one of the fds as
1825 sock\_fd.
1827 ``fmode=fmode``
1828 Specifies the default mode for newly created files on the host.
1829 Works only with security models "mapped-xattr" and
1830 "mapped-file".
1832 ``dmode=dmode``
1833 Specifies the default mode for newly created directories on the
1834 host. Works only with security models "mapped-xattr" and
1835 "mapped-file".
1837 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w``
1838 Specify bandwidth throttling limits in bytes per second, either
1839 for all request types or for reads or writes only.
1841 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm``
1842 Specify bursts in bytes per second, either for all request types
1843 or for reads or writes only. Bursts allow the guest I/O to spike
1844 above the limit temporarily.
1846 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w``
1847 Specify request rate limits in requests per second, either for
1848 all request types or for reads or writes only.
1850 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm``
1851 Specify bursts in requests per second, either for all request
1852 types or for reads or writes only. Bursts allow the guest I/O to
1853 spike above the limit temporarily.
1855 ``throttling.iops-size=is``
1856 Let every is bytes of a request count as a new request for iops
1857 throttling purposes.
1859 -fsdev option is used along with -device driver "virtio-9p-...".
1861 ``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag``
1862 Options for virtio-9p-... driver are:
1864 ``type``
1865 Specifies the variant to be used. Supported values are "pci",
1866 "ccw" or "device", depending on the machine type.
1868 ``fsdev=id``
1869 Specifies the id value specified along with -fsdev option.
1871 ``mount_tag=mount_tag``
1872 Specifies the tag name to be used by the guest to mount this
1873 export point.
1874 ERST
1876 DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1877 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1878 " [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1879 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n"
1880 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n"
1881 "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n",
1882 QEMU_ARCH_ALL)
1884 SRST
1885 ``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]``
1887 ``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1889 ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1891 ``-virtfs synth,mount_tag=mount_tag``
1892 Define a new virtual filesystem device and expose it to the guest using
1893 a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain
1894 directory on host is made directly accessible by guest as a pass-through
1895 file system by using the 9P network protocol for communication between
1896 host and guests, if desired even accessible, shared by several guests
1897 simultaneously.
1899 Note that ``-virtfs`` is actually just a convenience shortcut for its
1900 generalized form ``-fsdev -device virtio-9p-pci``.
1902 The general form of pass-through file system options are:
1904 ``local``
1905 Accesses to the filesystem are done by QEMU.
1907 ``proxy``
1908 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1909 This option is deprecated (since QEMU 8.1) and will be removed in a
1910 future version of QEMU. Use ``local`` instead.
1912 ``synth``
1913 Synthetic filesystem, only used by QTests.
1915 ``id=id``
1916 Specifies identifier for the filesystem device
1918 ``path=path``
1919 Specifies the export path for the file system device. Files
1920 under this path will be available to the 9p client on the guest.
1922 ``security_model=security_model``
1923 Specifies the security model to be used for this export path.
1924 Supported security models are "passthrough", "mapped-xattr",
1925 "mapped-file" and "none". In "passthrough" security model, files
1926 are stored using the same credentials as they are created on the
1927 guest. This requires QEMU to run as root. In "mapped-xattr"
1928 security model, some of the file attributes like uid, gid, mode
1929 bits and link target are stored as file attributes. For
1930 "mapped-file" these attributes are stored in the hidden
1931 .virtfs\_metadata directory. Directories exported by this
1932 security model cannot interact with other unix tools. "none"
1933 security model is same as passthrough except the sever won't
1934 report failures if it fails to set file attributes like
1935 ownership. Security model is mandatory only for local fsdriver.
1936 Other fsdrivers (like proxy) don't take security model as a
1937 parameter.
1939 ``writeout=writeout``
1940 This is an optional argument. The only supported value is
1941 "immediate". This means that host page cache will be used to
1942 read and write data but write notification will be sent to the
1943 guest only when the data has been reported as written by the
1944 storage subsystem.
1946 ``readonly=on``
1947 Enables exporting 9p share as a readonly mount for guests. By
1948 default read-write access is given.
1950 ``socket=socket``
1951 Enables proxy filesystem driver to use passed socket file for
1952 communicating with virtfs-proxy-helper(1). Usually a helper like
1953 libvirt will create socketpair and pass one of the fds as
1954 sock\_fd.
1956 ``sock_fd``
1957 Enables proxy filesystem driver to use passed 'sock\_fd' as the
1958 socket descriptor for interfacing with virtfs-proxy-helper(1).
1960 ``fmode=fmode``
1961 Specifies the default mode for newly created files on the host.
1962 Works only with security models "mapped-xattr" and
1963 "mapped-file".
1965 ``dmode=dmode``
1966 Specifies the default mode for newly created directories on the
1967 host. Works only with security models "mapped-xattr" and
1968 "mapped-file".
1970 ``mount_tag=mount_tag``
1971 Specifies the tag name to be used by the guest to mount this
1972 export point.
1974 ``multidevs=multidevs``
1975 Specifies how to deal with multiple devices being shared with a
1976 9p export. Supported behaviours are either "remap", "forbid" or
1977 "warn". The latter is the default behaviour on which virtfs 9p
1978 expects only one device to be shared with the same export, and
1979 if more than one device is shared and accessed via the same 9p
1980 export then only a warning message is logged (once) by qemu on
1981 host side. In order to avoid file ID collisions on guest you
1982 should either create a separate virtfs export for each device to
1983 be shared with guests (recommended way) or you might use "remap"
1984 instead which allows you to share multiple devices with only one
1985 export instead, which is achieved by remapping the original
1986 inode numbers from host to guest in a way that would prevent
1987 such collisions. Remapping inodes in such use cases is required
1988 because the original device IDs from host are never passed and
1989 exposed on guest. Instead all files of an export shared with
1990 virtfs always share the same device id on guest. So two files
1991 with identical inode numbers but from actually different devices
1992 on host would otherwise cause a file ID collision and hence
1993 potential misbehaviours on guest. "forbid" on the other hand
1994 assumes like "warn" that only one device is shared by the same
1995 export, however it will not only log a warning message but also
1996 deny access to additional devices on guest. Note though that
1997 "forbid" does currently not block all possible file access
1998 operations (e.g. readdir() would still return entries from other
1999 devices).
2000 ERST
2002 DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
2003 "-iscsi [user=user][,password=password][,password-secret=secret-id]\n"
2004 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE]\n"
2005 " [,initiator-name=initiator-iqn][,id=target-iqn]\n"
2006 " [,timeout=timeout]\n"
2007 " iSCSI session parameters\n", QEMU_ARCH_ALL)
2009 SRST
2010 ``-iscsi``
2011 Configure iSCSI session parameters.
2012 ERST
2014 DEFHEADING()
2016 DEFHEADING(USB convenience options:)
2018 DEF("usb", 0, QEMU_OPTION_usb,
2019 "-usb enable on-board USB host controller (if not enabled by default)\n",
2020 QEMU_ARCH_ALL)
2021 SRST
2022 ``-usb``
2023 Enable USB emulation on machine types with an on-board USB host
2024 controller (if not enabled by default). Note that on-board USB host
2025 controllers may not support USB 3.0. In this case
2026 ``-device qemu-xhci`` can be used instead on machines with PCI.
2027 ERST
2029 DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
2030 "-usbdevice name add the host or guest USB device 'name'\n",
2031 QEMU_ARCH_ALL)
2032 SRST
2033 ``-usbdevice devname``
2034 Add the USB device devname, and enable an on-board USB controller
2035 if possible and necessary (just like it can be done via
2036 ``-machine usb=on``). Note that this option is mainly intended for
2037 the user's convenience only. More fine-grained control can be
2038 achieved by selecting a USB host controller (if necessary) and the
2039 desired USB device via the ``-device`` option instead. For example,
2040 instead of using ``-usbdevice mouse`` it is possible to use
2041 ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse
2042 to a USB 3.0 controller instead (at least on machines that support
2043 PCI and do not have an USB controller enabled by default yet).
2044 For more details, see the chapter about
2045 :ref:`Connecting USB devices` in the System Emulation Users Guide.
2046 Possible devices for devname are:
2048 ``braille``
2049 Braille device. This will use BrlAPI to display the braille
2050 output on a real or fake device (i.e. it also creates a
2051 corresponding ``braille`` chardev automatically beside the
2052 ``usb-braille`` USB device).
2054 ``keyboard``
2055 Standard USB keyboard. Will override the PS/2 keyboard (if present).
2057 ``mouse``
2058 Virtual Mouse. This will override the PS/2 mouse emulation when
2059 activated.
2061 ``tablet``
2062 Pointer device that uses absolute coordinates (like a
2063 touchscreen). This means QEMU is able to report the mouse
2064 position without having to grab the mouse. Also overrides the
2065 PS/2 mouse emulation when activated.
2067 ``wacom-tablet``
2068 Wacom PenPartner USB tablet.
2071 ERST
2073 DEFHEADING()
2075 DEFHEADING(Display options:)
2077 DEF("display", HAS_ARG, QEMU_OPTION_display,
2078 #if defined(CONFIG_SPICE)
2079 "-display spice-app[,gl=on|off]\n"
2080 #endif
2081 #if defined(CONFIG_SDL)
2082 "-display sdl[,gl=on|core|es|off][,grab-mod=<mod>][,show-cursor=on|off]\n"
2083 " [,window-close=on|off]\n"
2084 #endif
2085 #if defined(CONFIG_GTK)
2086 "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
2087 " [,show-tabs=on|off][,show-cursor=on|off][,window-close=on|off]\n"
2088 " [,show-menubar=on|off]\n"
2089 #endif
2090 #if defined(CONFIG_VNC)
2091 "-display vnc=<display>[,<optargs>]\n"
2092 #endif
2093 #if defined(CONFIG_CURSES)
2094 "-display curses[,charset=<encoding>]\n"
2095 #endif
2096 #if defined(CONFIG_COCOA)
2097 "-display cocoa[,full-grab=on|off][,swap-opt-cmd=on|off]\n"
2098 " [,show-cursor=on|off][,left-command-key=on|off]\n"
2099 " [,full-screen=on|off][,zoom-to-fit=on|off]\n"
2100 #endif
2101 #if defined(CONFIG_OPENGL)
2102 "-display egl-headless[,rendernode=<file>]\n"
2103 #endif
2104 #if defined(CONFIG_DBUS_DISPLAY)
2105 "-display dbus[,addr=<dbusaddr>]\n"
2106 " [,gl=on|core|es|off][,rendernode=<file>]\n"
2107 #endif
2108 "-display none\n"
2109 " select display backend type\n"
2110 " The default display is equivalent to\n "
2111 #if defined(CONFIG_GTK)
2112 "\"-display gtk\"\n"
2113 #elif defined(CONFIG_SDL)
2114 "\"-display sdl\"\n"
2115 #elif defined(CONFIG_COCOA)
2116 "\"-display cocoa\"\n"
2117 #elif defined(CONFIG_VNC)
2118 "\"-vnc localhost:0,to=99,id=default\"\n"
2119 #else
2120 "\"-display none\"\n"
2121 #endif
2122 , QEMU_ARCH_ALL)
2123 SRST
2124 ``-display type``
2125 Select type of display to use. Use ``-display help`` to list the available
2126 display types. Valid values for type are
2128 ``spice-app[,gl=on|off]``
2129 Start QEMU as a Spice server and launch the default Spice client
2130 application. The Spice server will redirect the serial consoles
2131 and QEMU monitors. (Since 4.0)
2133 ``dbus``
2134 Export the display over D-Bus interfaces. (Since 7.0)
2136 The connection is registered with the "org.qemu" name (and queued when
2137 already owned).
2139 ``addr=<dbusaddr>`` : D-Bus bus address to connect to.
2141 ``p2p=yes|no`` : Use peer-to-peer connection, accepted via QMP ``add_client``.
2143 ``gl=on|off|core|es`` : Use OpenGL for rendering (the D-Bus interface
2144 will share framebuffers with DMABUF file descriptors).
2146 ``sdl``
2147 Display video output via SDL (usually in a separate graphics
2148 window; see the SDL documentation for other possibilities).
2149 Valid parameters are:
2151 ``grab-mod=<mods>`` : Used to select the modifier keys for toggling
2152 the mouse grabbing in conjunction with the "g" key. ``<mods>`` can be
2153 either ``lshift-lctrl-lalt`` or ``rctrl``.
2155 ``gl=on|off|core|es`` : Use OpenGL for displaying
2157 ``show-cursor=on|off`` : Force showing the mouse cursor
2159 ``window-close=on|off`` : Allow to quit qemu with window close button
2161 ``gtk``
2162 Display video output in a GTK window. This interface provides
2163 drop-down menus and other UI elements to configure and control
2164 the VM during runtime. Valid parameters are:
2166 ``full-screen=on|off`` : Start in fullscreen mode
2168 ``gl=on|off`` : Use OpenGL for displaying
2170 ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover
2172 ``show-tabs=on|off`` : Display the tab bar for switching between the
2173 various graphical interfaces (e.g. VGA and
2174 virtual console character devices) by default.
2176 ``show-cursor=on|off`` : Force showing the mouse cursor
2178 ``window-close=on|off`` : Allow to quit qemu with window close button
2180 ``show-menubar=on|off`` : Display the main window menubar, defaults to "on"
2182 ``zoom-to-fit=on|off`` : Expand video output to the window size,
2183 defaults to "off"
2185 ``curses[,charset=<encoding>]``
2186 Display video output via curses. For graphics device models
2187 which support a text mode, QEMU can display this output using a
2188 curses/ncurses interface. Nothing is displayed when the graphics
2189 device is in graphical mode or if the graphics device does not
2190 support a text mode. Generally only the VGA device models
2191 support text mode. The font charset used by the guest can be
2192 specified with the ``charset`` option, for example
2193 ``charset=CP850`` for IBM CP850 encoding. The default is
2194 ``CP437``.
2196 ``cocoa``
2197 Display video output in a Cocoa window. Mac only. This interface
2198 provides drop-down menus and other UI elements to configure and
2199 control the VM during runtime. Valid parameters are:
2201 ``full-grab=on|off`` : Capture all key presses, including system combos.
2202 This requires accessibility permissions, since it
2203 performs a global grab on key events.
2204 (default: off) See
2205 https://support.apple.com/en-in/guide/mac-help/mh32356/mac
2207 ``swap-opt-cmd=on|off`` : Swap the Option and Command keys so that their
2208 key codes match their position on non-Mac
2209 keyboards and you can use Meta/Super and Alt
2210 where you expect them. (default: off)
2212 ``show-cursor=on|off`` : Force showing the mouse cursor
2214 ``left-command-key=on|off`` : Disable forwarding left command key to host
2216 ``full-screen=on|off`` : Start in fullscreen mode
2218 ``zoom-to-fit=on|off`` : Expand video output to the window size,
2219 defaults to "off"
2221 ``egl-headless[,rendernode=<file>]``
2222 Offload all OpenGL operations to a local DRI device. For any
2223 graphical display, this display needs to be paired with either
2224 VNC or SPICE displays.
2226 ``vnc=<display>``
2227 Start a VNC server on display <display>
2229 ``none``
2230 Do not display video output. The guest will still see an
2231 emulated graphics card, but its output will not be displayed to
2232 the QEMU user. This option differs from the -nographic option in
2233 that it only affects what is done with video output; -nographic
2234 also changes the destination of the serial and parallel port
2235 data.
2236 ERST
2238 DEF("nographic", 0, QEMU_OPTION_nographic,
2239 "-nographic disable graphical output and redirect serial I/Os to console\n",
2240 QEMU_ARCH_ALL)
2241 SRST
2242 ``-nographic``
2243 Normally, if QEMU is compiled with graphical window support, it
2244 displays output such as guest graphics, guest console, and the QEMU
2245 monitor in a window. With this option, you can totally disable
2246 graphical output so that QEMU is a simple command line application.
2247 The emulated serial port is redirected on the console and muxed with
2248 the monitor (unless redirected elsewhere explicitly). Therefore, you
2249 can still use QEMU to debug a Linux kernel with a serial console.
2250 Use C-a h for help on switching between the console and monitor.
2251 ERST
2253 #ifdef CONFIG_SPICE
2254 DEF("spice", HAS_ARG, QEMU_OPTION_spice,
2255 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
2256 " [,x509-key-file=<file>][,x509-key-password=<file>]\n"
2257 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
2258 " [,x509-dh-key-file=<file>][,addr=addr]\n"
2259 " [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n"
2260 " [,tls-ciphers=<list>]\n"
2261 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
2262 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
2263 " [,sasl=on|off][,disable-ticketing=on|off]\n"
2264 " [,password-secret=<secret-id>]\n"
2265 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
2266 " [,jpeg-wan-compression=[auto|never|always]]\n"
2267 " [,zlib-glz-wan-compression=[auto|never|always]]\n"
2268 " [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n"
2269 " [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n"
2270 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
2271 " [,gl=[on|off]][,rendernode=<file>]\n"
2272 " enable spice\n"
2273 " at least one of {port, tls-port} is mandatory\n",
2274 QEMU_ARCH_ALL)
2275 #endif
2276 SRST
2277 ``-spice option[,option[,...]]``
2278 Enable the spice remote desktop protocol. Valid options are
2280 ``port=<nr>``
2281 Set the TCP port spice is listening on for plaintext channels.
2283 ``addr=<addr>``
2284 Set the IP address spice is listening on. Default is any
2285 address.
2287 ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off``
2288 Force using the specified IP version.
2290 ``password-secret=<secret-id>``
2291 Set the ID of the ``secret`` object containing the password
2292 you need to authenticate.
2294 ``sasl=on|off``
2295 Require that the client use SASL to authenticate with the spice.
2296 The exact choice of authentication method used is controlled
2297 from the system / user's SASL configuration file for the 'qemu'
2298 service. This is typically found in /etc/sasl2/qemu.conf. If
2299 running QEMU as an unprivileged user, an environment variable
2300 SASL\_CONF\_PATH can be used to make it search alternate
2301 locations for the service config. While some SASL auth methods
2302 can also provide data encryption (eg GSSAPI), it is recommended
2303 that SASL always be combined with the 'tls' and 'x509' settings
2304 to enable use of SSL and server certificates. This ensures a
2305 data encryption preventing compromise of authentication
2306 credentials.
2308 ``disable-ticketing=on|off``
2309 Allow client connects without authentication.
2311 ``disable-copy-paste=on|off``
2312 Disable copy paste between the client and the guest.
2314 ``disable-agent-file-xfer=on|off``
2315 Disable spice-vdagent based file-xfer between the client and the
2316 guest.
2318 ``tls-port=<nr>``
2319 Set the TCP port spice is listening on for encrypted channels.
2321 ``x509-dir=<dir>``
2322 Set the x509 file directory. Expects same filenames as -vnc
2323 $display,x509=$dir
2325 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>``
2326 The x509 file names can also be configured individually.
2328 ``tls-ciphers=<list>``
2329 Specify which ciphers to use.
2331 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]``
2332 Force specific channel to be used with or without TLS
2333 encryption. The options can be specified multiple times to
2334 configure multiple channels. The special name "default" can be
2335 used to set the default mode. For channels which are not
2336 explicitly forced into one mode the spice client is allowed to
2337 pick tls/plaintext as he pleases.
2339 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]``
2340 Configure image compression (lossless). Default is auto\_glz.
2342 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]``
2343 Configure wan image compression (lossy for slow links). Default
2344 is auto.
2346 ``streaming-video=[off|all|filter]``
2347 Configure video stream detection. Default is off.
2349 ``agent-mouse=[on|off]``
2350 Enable/disable passing mouse events via vdagent. Default is on.
2352 ``playback-compression=[on|off]``
2353 Enable/disable audio stream compression (using celt 0.5.1).
2354 Default is on.
2356 ``seamless-migration=[on|off]``
2357 Enable/disable spice seamless migration. Default is off.
2359 ``gl=[on|off]``
2360 Enable/disable OpenGL context. Default is off.
2362 ``rendernode=<file>``
2363 DRM render node for OpenGL rendering. If not specified, it will
2364 pick the first available. (Since 2.9)
2365 ERST
2367 DEF("portrait", 0, QEMU_OPTION_portrait,
2368 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n",
2369 QEMU_ARCH_ALL)
2370 SRST
2371 ``-portrait``
2372 Rotate graphical output 90 deg left (only PXA LCD).
2373 ERST
2375 DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
2376 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n",
2377 QEMU_ARCH_ALL)
2378 SRST
2379 ``-rotate deg``
2380 Rotate graphical output some deg left (only PXA LCD).
2381 ERST
2383 DEF("vga", HAS_ARG, QEMU_OPTION_vga,
2384 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
2385 " select video card type\n", QEMU_ARCH_ALL)
2386 SRST
2387 ``-vga type``
2388 Select type of VGA card to emulate. Valid values for type are
2390 ``cirrus``
2391 Cirrus Logic GD5446 Video card. All Windows versions starting
2392 from Windows 95 should recognize and use this graphic card. For
2393 optimal performances, use 16 bit color depth in the guest and
2394 the host OS. (This card was the default before QEMU 2.2)
2396 ``std``
2397 Standard VGA card with Bochs VBE extensions. If your guest OS
2398 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
2399 you want to use high resolution modes (>= 1280x1024x16) then you
2400 should use this option. (This card is the default since QEMU
2401 2.2)
2403 ``vmware``
2404 VMWare SVGA-II compatible adapter. Use it if you have
2405 sufficiently recent XFree86/XOrg server or Windows guest with a
2406 driver for this card.
2408 ``qxl``
2409 QXL paravirtual graphic card. It is VGA compatible (including
2410 VESA 2.0 VBE support). Works best with qxl guest drivers
2411 installed though. Recommended choice when using the spice
2412 protocol.
2414 ``tcx``
2415 (sun4m only) Sun TCX framebuffer. This is the default
2416 framebuffer for sun4m machines and offers both 8-bit and 24-bit
2417 colour depths at a fixed resolution of 1024x768.
2419 ``cg3``
2420 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit
2421 framebuffer for sun4m machines available in both 1024x768
2422 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people
2423 wishing to run older Solaris versions.
2425 ``virtio``
2426 Virtio VGA card.
2428 ``none``
2429 Disable VGA card.
2430 ERST
2432 DEF("full-screen", 0, QEMU_OPTION_full_screen,
2433 "-full-screen start in full screen\n", QEMU_ARCH_ALL)
2434 SRST
2435 ``-full-screen``
2436 Start in full screen.
2437 ERST
2439 DEF("g", HAS_ARG, QEMU_OPTION_g ,
2440 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n",
2441 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K)
2442 SRST
2443 ``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]``
2444 Set the initial graphical resolution and depth (PPC, SPARC only).
2446 For PPC the default is 800x600x32.
2448 For SPARC with the TCX graphics device, the default is 1024x768x8
2449 with the option of 1024x768x24. For cgthree, the default is
2450 1024x768x8 with the option of 1152x900x8 for people who wish to use
2451 OBP.
2452 ERST
2454 #ifdef CONFIG_VNC
2455 DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
2456 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
2457 #endif
2458 SRST
2459 ``-vnc display[,option[,option[,...]]]``
2460 Normally, if QEMU is compiled with graphical window support, it
2461 displays output such as guest graphics, guest console, and the QEMU
2462 monitor in a window. With this option, you can have QEMU listen on
2463 VNC display display and redirect the VGA display over the VNC
2464 session. It is very useful to enable the usb tablet device when
2465 using this option (option ``-device usb-tablet``). When using the
2466 VNC display, you must use the ``-k`` parameter to set the keyboard
2467 layout if you are not using en-us. Valid syntax for the display is
2469 ``to=L``
2470 With this option, QEMU will try next available VNC displays,
2471 until the number L, if the origianlly defined "-vnc display" is
2472 not available, e.g. port 5900+display is already used by another
2473 application. By default, to=0.
2475 ``host:d``
2476 TCP connections will only be allowed from host on display d. By
2477 convention the TCP port is 5900+d. Optionally, host can be
2478 omitted in which case the server will accept connections from
2479 any host.
2481 ``unix:path``
2482 Connections will be allowed over UNIX domain sockets where path
2483 is the location of a unix socket to listen for connections on.
2485 ``none``
2486 VNC is initialized but not started. The monitor ``change``
2487 command can be used to later start the VNC server.
2489 Following the display value there may be one or more option flags
2490 separated by commas. Valid options are
2492 ``reverse=on|off``
2493 Connect to a listening VNC client via a "reverse" connection.
2494 The client is specified by the display. For reverse network
2495 connections (host:d,``reverse``), the d argument is a TCP port
2496 number, not a display number.
2498 ``websocket=on|off``
2499 Opens an additional TCP listening port dedicated to VNC
2500 Websocket connections. If a bare websocket option is given, the
2501 Websocket port is 5700+display. An alternative port can be
2502 specified with the syntax ``websocket``\ =port.
2504 If host is specified connections will only be allowed from this
2505 host. It is possible to control the websocket listen address
2506 independently, using the syntax ``websocket``\ =host:port.
2508 If no TLS credentials are provided, the websocket connection
2509 runs in unencrypted mode. If TLS credentials are provided, the
2510 websocket connection requires encrypted client connections.
2512 ``password=on|off``
2513 Require that password based authentication is used for client
2514 connections.
2516 The password must be set separately using the ``set_password``
2517 command in the :ref:`QEMU monitor`. The
2518 syntax to change your password is:
2519 ``set_password <protocol> <password>`` where <protocol> could be
2520 either "vnc" or "spice".
2522 If you would like to change <protocol> password expiration, you
2523 should use ``expire_password <protocol> <expiration-time>``
2524 where expiration time could be one of the following options:
2525 now, never, +seconds or UNIX time of expiration, e.g. +60 to
2526 make password expire in 60 seconds, or 1335196800 to make
2527 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for
2528 this date and time).
2530 You can also use keywords "now" or "never" for the expiration
2531 time to allow <protocol> password to expire immediately or never
2532 expire.
2534 ``password-secret=<secret-id>``
2535 Require that password based authentication is used for client
2536 connections, using the password provided by the ``secret``
2537 object identified by ``secret-id``.
2539 ``tls-creds=ID``
2540 Provides the ID of a set of TLS credentials to use to secure the
2541 VNC server. They will apply to both the normal VNC server socket
2542 and the websocket socket (if enabled). Setting TLS credentials
2543 will cause the VNC server socket to enable the VeNCrypt auth
2544 mechanism. The credentials should have been previously created
2545 using the ``-object tls-creds`` argument.
2547 ``tls-authz=ID``
2548 Provides the ID of the QAuthZ authorization object against which
2549 the client's x509 distinguished name will validated. This object
2550 is only resolved at time of use, so can be deleted and recreated
2551 on the fly while the VNC server is active. If missing, it will
2552 default to denying access.
2554 ``sasl=on|off``
2555 Require that the client use SASL to authenticate with the VNC
2556 server. The exact choice of authentication method used is
2557 controlled from the system / user's SASL configuration file for
2558 the 'qemu' service. This is typically found in
2559 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
2560 an environment variable SASL\_CONF\_PATH can be used to make it
2561 search alternate locations for the service config. While some
2562 SASL auth methods can also provide data encryption (eg GSSAPI),
2563 it is recommended that SASL always be combined with the 'tls'
2564 and 'x509' settings to enable use of SSL and server
2565 certificates. This ensures a data encryption preventing
2566 compromise of authentication credentials. See the
2567 :ref:`VNC security` section in the System Emulation Users Guide
2568 for details on using SASL authentication.
2570 ``sasl-authz=ID``
2571 Provides the ID of the QAuthZ authorization object against which
2572 the client's SASL username will validated. This object is only
2573 resolved at time of use, so can be deleted and recreated on the
2574 fly while the VNC server is active. If missing, it will default
2575 to denying access.
2577 ``acl=on|off``
2578 Legacy method for enabling authorization of clients against the
2579 x509 distinguished name and SASL username. It results in the
2580 creation of two ``authz-list`` objects with IDs of
2581 ``vnc.username`` and ``vnc.x509dname``. The rules for these
2582 objects must be configured with the HMP ACL commands.
2584 This option is deprecated and should no longer be used. The new
2585 ``sasl-authz`` and ``tls-authz`` options are a replacement.
2587 ``lossy=on|off``
2588 Enable lossy compression methods (gradient, JPEG, ...). If this
2589 option is set, VNC client may receive lossy framebuffer updates
2590 depending on its encoding settings. Enabling this option can
2591 save a lot of bandwidth at the expense of quality.
2593 ``non-adaptive=on|off``
2594 Disable adaptive encodings. Adaptive encodings are enabled by
2595 default. An adaptive encoding will try to detect frequently
2596 updated screen regions, and send updates in these regions using
2597 a lossy encoding (like JPEG). This can be really helpful to save
2598 bandwidth when playing videos. Disabling adaptive encodings
2599 restores the original static behavior of encodings like Tight.
2601 ``share=[allow-exclusive|force-shared|ignore]``
2602 Set display sharing policy. 'allow-exclusive' allows clients to
2603 ask for exclusive access. As suggested by the rfb spec this is
2604 implemented by dropping other connections. Connecting multiple
2605 clients in parallel requires all clients asking for a shared
2606 session (vncviewer: -shared switch). This is the default.
2607 'force-shared' disables exclusive client access. Useful for
2608 shared desktop sessions, where you don't want someone forgetting
2609 specify -shared disconnect everybody else. 'ignore' completely
2610 ignores the shared flag and allows everybody connect
2611 unconditionally. Doesn't conform to the rfb spec but is
2612 traditional QEMU behavior.
2614 ``key-delay-ms``
2615 Set keyboard delay, for key down and key up events, in
2616 milliseconds. Default is 10. Keyboards are low-bandwidth
2617 devices, so this slowdown can help the device and guest to keep
2618 up and not lose events in case events are arriving in bulk.
2619 Possible causes for the latter are flaky network connections, or
2620 scripts for automated testing.
2622 ``audiodev=audiodev``
2623 Use the specified audiodev when the VNC client requests audio
2624 transmission. When not using an -audiodev argument, this option
2625 must be omitted, otherwise is must be present and specify a
2626 valid audiodev.
2628 ``power-control=on|off``
2629 Permit the remote client to issue shutdown, reboot or reset power
2630 control requests.
2631 ERST
2633 ARCHHEADING(, QEMU_ARCH_I386)
2635 ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2637 DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2638 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n",
2639 QEMU_ARCH_I386)
2640 SRST
2641 ``-win2k-hack``
2642 Use it when installing Windows 2000 to avoid a disk full bug. After
2643 Windows 2000 is installed, you no longer need this option (this
2644 option slows down the IDE transfers).
2645 ERST
2647 DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2648 "-no-fd-bootchk disable boot signature checking for floppy disks\n",
2649 QEMU_ARCH_I386)
2650 SRST
2651 ``-no-fd-bootchk``
2652 Disable boot signature checking for floppy disks in BIOS. May be
2653 needed to boot from old floppy disks.
2654 ERST
2656 DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2657 "-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"
2658 " ACPI table description\n", QEMU_ARCH_I386)
2659 SRST
2660 ``-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]...]``
2661 Add ACPI table with specified header fields and context from
2662 specified files. For file=, take whole ACPI table from the specified
2663 files, including all ACPI headers (possible overridden by other
2664 options). For data=, only data portion of the table is used, all
2665 header information is specified in the command line. If a SLIC table
2666 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
2667 fields will override the same in the RSDT and the FADT (a.k.a.
2668 FACP), in order to ensure the field matches required by the
2669 Microsoft SLIC spec and the ACPI spec.
2670 ERST
2672 DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2673 "-smbios file=binary\n"
2674 " load SMBIOS entry from binary file\n"
2675 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2676 " [,uefi=on|off]\n"
2677 " specify SMBIOS type 0 fields\n"
2678 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2679 " [,uuid=uuid][,sku=str][,family=str]\n"
2680 " specify SMBIOS type 1 fields\n"
2681 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2682 " [,asset=str][,location=str]\n"
2683 " specify SMBIOS type 2 fields\n"
2684 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2685 " [,sku=str]\n"
2686 " specify SMBIOS type 3 fields\n"
2687 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2688 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
2689 " [,processor-id=%d]\n"
2690 " specify SMBIOS type 4 fields\n"
2691 "-smbios type=8[,external_reference=str][,internal_reference=str][,connector_type=%d][,port_type=%d]\n"
2692 " specify SMBIOS type 8 fields\n"
2693 "-smbios type=11[,value=str][,path=filename]\n"
2694 " specify SMBIOS type 11 fields\n"
2695 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2696 " [,asset=str][,part=str][,speed=%d]\n"
2697 " specify SMBIOS type 17 fields\n"
2698 "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n"
2699 " specify SMBIOS type 41 fields\n",
2700 QEMU_ARCH_I386 | QEMU_ARCH_ARM | QEMU_ARCH_LOONGARCH)
2701 SRST
2702 ``-smbios file=binary``
2703 Load SMBIOS entry from binary file.
2705 ``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]``
2706 Specify SMBIOS type 0 fields
2708 ``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]``
2709 Specify SMBIOS type 1 fields
2711 ``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]``
2712 Specify SMBIOS type 2 fields
2714 ``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
2715 Specify SMBIOS type 3 fields
2717 ``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str][,processor-id=%d]``
2718 Specify SMBIOS type 4 fields
2720 ``-smbios type=11[,value=str][,path=filename]``
2721 Specify SMBIOS type 11 fields
2723 This argument can be repeated multiple times, and values are added in the order they are parsed.
2724 Applications intending to use OEM strings data are encouraged to use their application name as
2725 a prefix for the value string. This facilitates passing information for multiple applications
2726 concurrently.
2728 The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax
2729 loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes.
2731 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to
2732 the SMBIOS table in the order in which they appear.
2734 Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535
2735 bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the
2736 guest. Instead it should be used as a indicator to inform the guest where to locate the real
2737 data set, for example, by specifying the serial ID of a block device.
2739 An example passing three strings is
2741 .. parsed-literal::
2743 -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\
2744 value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\
2745 path=/some/file/with/oemstringsdata.txt
2747 In the guest OS this is visible with the ``dmidecode`` command
2749 .. parsed-literal::
2751 $ dmidecode -t 11
2752 Handle 0x0E00, DMI type 11, 5 bytes
2753 OEM Strings
2754 String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/
2755 String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os
2756 String 3: myapp:some extra data
2759 ``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]``
2760 Specify SMBIOS type 17 fields
2762 ``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]``
2763 Specify SMBIOS type 41 fields
2765 This argument can be repeated multiple times. Its main use is to allow network interfaces be created
2766 as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface
2767 position on the PCI bus.
2769 Here is an example of use:
2771 .. parsed-literal::
2773 -netdev user,id=internet \\
2774 -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\
2775 -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev
2777 In the guest OS, the device should then appear as ``eno1``:
2779 ..parsed-literal::
2781 $ ip -brief l
2782 lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP>
2783 eno1 UP 50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP>
2785 Currently, the PCI device has to be attached to the root bus.
2787 ERST
2789 DEFHEADING()
2791 DEFHEADING(Network options:)
2793 DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2794 #ifdef CONFIG_SLIRP
2795 "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n"
2796 " [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2797 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2798 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2799 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2800 #ifndef _WIN32
2801 "[,smb=dir[,smbserver=addr]]\n"
2802 #endif
2803 " configure a user mode network backend with ID 'str',\n"
2804 " its DHCP server and optional services\n"
2805 #endif
2806 #ifdef _WIN32
2807 "-netdev tap,id=str,ifname=name\n"
2808 " configure a host TAP network backend with ID 'str'\n"
2809 #else
2810 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2811 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2812 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2813 " [,poll-us=n]\n"
2814 " configure a host TAP network backend with ID 'str'\n"
2815 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2816 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2817 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2818 " to deconfigure it\n"
2819 " use '[down]script=no' to disable script execution\n"
2820 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2821 " configure it\n"
2822 " use 'fd=h' to connect to an already opened TAP interface\n"
2823 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2824 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2825 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2826 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2827 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2828 " use vhost=on to enable experimental in kernel accelerator\n"
2829 " (only has effect for virtio guests which use MSIX)\n"
2830 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2831 " use 'vhostfd=h' to connect to an already opened vhost net device\n"
2832 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2833 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2834 " use 'poll-us=n' to specify the maximum number of microseconds that could be\n"
2835 " spent on busy polling for vhost net\n"
2836 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2837 " configure a host TAP network backend with ID 'str' that is\n"
2838 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2839 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2840 #endif
2841 #ifdef __linux__
2842 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2843 " [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n"
2844 " [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n"
2845 " [,rxcookie=rxcookie][,offset=offset]\n"
2846 " configure a network backend with ID 'str' connected to\n"
2847 " an Ethernet over L2TPv3 pseudowire.\n"
2848 " Linux kernel 3.3+ as well as most routers can talk\n"
2849 " L2TPv3. This transport allows connecting a VM to a VM,\n"
2850 " VM to a router and even VM to Host. It is a nearly-universal\n"
2851 " standard (RFC3931). Note - this implementation uses static\n"
2852 " pre-configured tunnels (same as the Linux kernel).\n"
2853 " use 'src=' to specify source address\n"
2854 " use 'dst=' to specify destination address\n"
2855 " use 'udp=on' to specify udp encapsulation\n"
2856 " use 'srcport=' to specify source udp port\n"
2857 " use 'dstport=' to specify destination udp port\n"
2858 " use 'ipv6=on' to force v6\n"
2859 " L2TPv3 uses cookies to prevent misconfiguration as\n"
2860 " well as a weak security measure\n"
2861 " use 'rxcookie=0x012345678' to specify a rxcookie\n"
2862 " use 'txcookie=0x012345678' to specify a txcookie\n"
2863 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2864 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2865 " use 'pincounter=on' to work around broken counter handling in peer\n"
2866 " use 'offset=X' to add an extra offset between header and data\n"
2867 #endif
2868 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2869 " configure a network backend to connect to another network\n"
2870 " using a socket connection\n"
2871 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2872 " configure a network backend to connect to a multicast maddr and port\n"
2873 " use 'localaddr=addr' to specify the host address to send packets from\n"
2874 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2875 " configure a network backend to connect to another network\n"
2876 " using an UDP tunnel\n"
2877 "-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"
2878 "-netdev stream,id=str[,server=on|off],addr.type=unix,addr.path=path[,abstract=on|off][,tight=on|off][,reconnect=seconds]\n"
2879 "-netdev stream,id=str[,server=on|off],addr.type=fd,addr.str=file-descriptor[,reconnect=seconds]\n"
2880 " configure a network backend to connect to another network\n"
2881 " using a socket connection in stream mode.\n"
2882 "-netdev dgram,id=str,remote.type=inet,remote.host=maddr,remote.port=port[,local.type=inet,local.host=addr]\n"
2883 "-netdev dgram,id=str,remote.type=inet,remote.host=maddr,remote.port=port[,local.type=fd,local.str=file-descriptor]\n"
2884 " configure a network backend to connect to a multicast maddr and port\n"
2885 " use ``local.host=addr`` to specify the host address to send packets from\n"
2886 "-netdev dgram,id=str,local.type=inet,local.host=addr,local.port=port[,remote.type=inet,remote.host=addr,remote.port=port]\n"
2887 "-netdev dgram,id=str,local.type=unix,local.path=path[,remote.type=unix,remote.path=path]\n"
2888 "-netdev dgram,id=str,local.type=fd,local.str=file-descriptor\n"
2889 " configure a network backend to connect to another network\n"
2890 " using an UDP tunnel\n"
2891 #ifdef CONFIG_VDE
2892 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2893 " configure a network backend to connect to port 'n' of a vde switch\n"
2894 " running on host and listening for incoming connections on 'socketpath'.\n"
2895 " Use group 'groupname' and mode 'octalmode' to change default\n"
2896 " ownership and permissions for communication port.\n"
2897 #endif
2898 #ifdef CONFIG_NETMAP
2899 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2900 " attach to the existing netmap-enabled network interface 'name', or to a\n"
2901 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2902 " netmap device, defaults to '/dev/netmap')\n"
2903 #endif
2904 #ifdef CONFIG_AF_XDP
2905 "-netdev af-xdp,id=str,ifname=name[,mode=native|skb][,force-copy=on|off]\n"
2906 " [,queues=n][,start-queue=m][,inhibit=on|off][,sock-fds=x:y:...:z]\n"
2907 " attach to the existing network interface 'name' with AF_XDP socket\n"
2908 " use 'mode=MODE' to specify an XDP program attach mode\n"
2909 " use 'force-copy=on|off' to force XDP copy mode even if device supports zero-copy (default: off)\n"
2910 " use 'inhibit=on|off' to inhibit loading of a default XDP program (default: off)\n"
2911 " with inhibit=on,\n"
2912 " use 'sock-fds' to provide file descriptors for already open AF_XDP sockets\n"
2913 " added to a socket map in XDP program. One socket per queue.\n"
2914 " use 'queues=n' to specify how many queues of a multiqueue interface should be used\n"
2915 " use 'start-queue=m' to specify the first queue that should be used\n"
2916 #endif
2917 #ifdef CONFIG_POSIX
2918 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2919 " configure a vhost-user network, backed by a chardev 'dev'\n"
2920 #endif
2921 #ifdef __linux__
2922 "-netdev vhost-vdpa,id=str[,vhostdev=/path/to/dev][,vhostfd=h]\n"
2923 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n"
2924 " use 'vhostdev=/path/to/dev' to open a vhost vdpa device\n"
2925 " use 'vhostfd=h' to connect to an already opened vhost vdpa device\n"
2926 #endif
2927 #ifdef CONFIG_VMNET
2928 "-netdev vmnet-host,id=str[,isolated=on|off][,net-uuid=uuid]\n"
2929 " [,start-address=addr,end-address=addr,subnet-mask=mask]\n"
2930 " configure a vmnet network backend in host mode with ID 'str',\n"
2931 " isolate this interface from others with 'isolated',\n"
2932 " configure the address range and choose a subnet mask,\n"
2933 " specify network UUID 'uuid' to disable DHCP and interact with\n"
2934 " vmnet-host interfaces within this isolated network\n"
2935 "-netdev vmnet-shared,id=str[,isolated=on|off][,nat66-prefix=addr]\n"
2936 " [,start-address=addr,end-address=addr,subnet-mask=mask]\n"
2937 " configure a vmnet network backend in shared mode with ID 'str',\n"
2938 " configure the address range and choose a subnet mask,\n"
2939 " set IPv6 ULA prefix (of length 64) to use for internal network,\n"
2940 " isolate this interface from others with 'isolated'\n"
2941 "-netdev vmnet-bridged,id=str,ifname=name[,isolated=on|off]\n"
2942 " configure a vmnet network backend in bridged mode with ID 'str',\n"
2943 " use 'ifname=name' to select a physical network interface to be bridged,\n"
2944 " isolate this interface from others with 'isolated'\n"
2945 #endif
2946 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2947 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2948 DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2949 "-nic [tap|bridge|"
2950 #ifdef CONFIG_SLIRP
2951 "user|"
2952 #endif
2953 #ifdef __linux__
2954 "l2tpv3|"
2955 #endif
2956 #ifdef CONFIG_VDE
2957 "vde|"
2958 #endif
2959 #ifdef CONFIG_NETMAP
2960 "netmap|"
2961 #endif
2962 #ifdef CONFIG_AF_XDP
2963 "af-xdp|"
2964 #endif
2965 #ifdef CONFIG_POSIX
2966 "vhost-user|"
2967 #endif
2968 #ifdef CONFIG_VMNET
2969 "vmnet-host|vmnet-shared|vmnet-bridged|"
2970 #endif
2971 "socket][,option][,...][mac=macaddr]\n"
2972 " initialize an on-board / default host NIC (using MAC address\n"
2973 " macaddr) and connect it to the given host network backend\n"
2974 "-nic none use it alone to have zero network devices (the default is to\n"
2975 " provided a 'user' network connection)\n",
2976 QEMU_ARCH_ALL)
2977 DEF("net", HAS_ARG, QEMU_OPTION_net,
2978 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2979 " configure or create an on-board (or machine default) NIC and\n"
2980 " connect it to hub 0 (please use -nic unless you need a hub)\n"
2981 "-net ["
2982 #ifdef CONFIG_SLIRP
2983 "user|"
2984 #endif
2985 "tap|"
2986 "bridge|"
2987 #ifdef CONFIG_VDE
2988 "vde|"
2989 #endif
2990 #ifdef CONFIG_NETMAP
2991 "netmap|"
2992 #endif
2993 #ifdef CONFIG_AF_XDP
2994 "af-xdp|"
2995 #endif
2996 #ifdef CONFIG_VMNET
2997 "vmnet-host|vmnet-shared|vmnet-bridged|"
2998 #endif
2999 "socket][,option][,option][,...]\n"
3000 " old way to initialize a host network interface\n"
3001 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
3002 SRST
3003 ``-nic [tap|bridge|user|l2tpv3|vde|netmap|af-xdp|vhost-user|socket][,...][,mac=macaddr][,model=mn]``
3004 This option is a shortcut for configuring both the on-board
3005 (default) guest NIC hardware and the host network backend in one go.
3006 The host backend options are the same as with the corresponding
3007 ``-netdev`` options below. The guest NIC model can be set with
3008 ``model=modelname``. Use ``model=help`` to list the available device
3009 types. The hardware MAC address can be set with ``mac=macaddr``.
3011 The following two example do exactly the same, to show how ``-nic``
3012 can be used to shorten the command line length:
3014 .. parsed-literal::
3016 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
3017 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
3019 ``-nic none``
3020 Indicate that no network devices should be configured. It is used to
3021 override the default configuration (default NIC with "user" host
3022 network backend) which is activated if no other networking options
3023 are provided.
3025 ``-netdev user,id=id[,option][,option][,...]``
3026 Configure user mode host network backend which requires no
3027 administrator privilege to run. Valid options are:
3029 ``id=id``
3030 Assign symbolic name for use in monitor commands.
3032 ``ipv4=on|off and ipv6=on|off``
3033 Specify that either IPv4 or IPv6 must be enabled. If neither is
3034 specified both protocols are enabled.
3036 ``net=addr[/mask]``
3037 Set IP network address the guest will see. Optionally specify
3038 the netmask, either in the form a.b.c.d or as number of valid
3039 top-most bits. Default is 10.0.2.0/24.
3041 ``host=addr``
3042 Specify the guest-visible address of the host. Default is the
3043 2nd IP in the guest network, i.e. x.x.x.2.
3045 ``ipv6-net=addr[/int]``
3046 Set IPv6 network address the guest will see (default is
3047 fec0::/64). The network prefix is given in the usual hexadecimal
3048 IPv6 address notation. The prefix size is optional, and is given
3049 as the number of valid top-most bits (default is 64).
3051 ``ipv6-host=addr``
3052 Specify the guest-visible IPv6 address of the host. Default is
3053 the 2nd IPv6 in the guest network, i.e. xxxx::2.
3055 ``restrict=on|off``
3056 If this option is enabled, the guest will be isolated, i.e. it
3057 will not be able to contact the host and no guest IP packets
3058 will be routed over the host to the outside. This option does
3059 not affect any explicitly set forwarding rules.
3061 ``hostname=name``
3062 Specifies the client hostname reported by the built-in DHCP
3063 server.
3065 ``dhcpstart=addr``
3066 Specify the first of the 16 IPs the built-in DHCP server can
3067 assign. Default is the 15th to 31st IP in the guest network,
3068 i.e. x.x.x.15 to x.x.x.31.
3070 ``dns=addr``
3071 Specify the guest-visible address of the virtual nameserver. The
3072 address must be different from the host address. Default is the
3073 3rd IP in the guest network, i.e. x.x.x.3.
3075 ``ipv6-dns=addr``
3076 Specify the guest-visible address of the IPv6 virtual
3077 nameserver. The address must be different from the host address.
3078 Default is the 3rd IP in the guest network, i.e. xxxx::3.
3080 ``dnssearch=domain``
3081 Provides an entry for the domain-search list sent by the
3082 built-in DHCP server. More than one domain suffix can be
3083 transmitted by specifying this option multiple times. If
3084 supported, this will cause the guest to automatically try to
3085 append the given domain suffix(es) in case a domain name can not
3086 be resolved.
3088 Example:
3090 .. parsed-literal::
3092 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
3094 ``domainname=domain``
3095 Specifies the client domain name reported by the built-in DHCP
3096 server.
3098 ``tftp=dir``
3099 When using the user mode network stack, activate a built-in TFTP
3100 server. The files in dir will be exposed as the root of a TFTP
3101 server. The TFTP client on the guest must be configured in
3102 binary mode (use the command ``bin`` of the Unix TFTP client).
3104 ``tftp-server-name=name``
3105 In BOOTP reply, broadcast name as the "TFTP server name"
3106 (RFC2132 option 66). This can be used to advise the guest to
3107 load boot files or configurations from a different server than
3108 the host address.
3110 ``bootfile=file``
3111 When using the user mode network stack, broadcast file as the
3112 BOOTP filename. In conjunction with ``tftp``, this can be used
3113 to network boot a guest from a local directory.
3115 Example (using pxelinux):
3117 .. parsed-literal::
3119 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\
3120 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
3122 ``smb=dir[,smbserver=addr]``
3123 When using the user mode network stack, activate a built-in SMB
3124 server so that Windows OSes can access to the host files in
3125 ``dir`` transparently. The IP address of the SMB server can be
3126 set to addr. By default the 4th IP in the guest network is used,
3127 i.e. x.x.x.4.
3129 In the guest Windows OS, the line:
3133 10.0.2.4 smbserver
3135 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows
3136 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows
3137 NT/2000).
3139 Then ``dir`` can be accessed in ``\\smbserver\qemu``.
3141 Note that a SAMBA server must be installed on the host OS.
3143 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
3144 Redirect incoming TCP or UDP connections to the host port
3145 hostport to the guest IP address guestaddr on guest port
3146 guestport. If guestaddr is not specified, its value is x.x.x.15
3147 (default first address given by the built-in DHCP server). By
3148 specifying hostaddr, the rule can be bound to a specific host
3149 interface. If no connection type is set, TCP is used. This
3150 option can be given multiple times.
3152 For example, to redirect host X11 connection from screen 1 to
3153 guest screen 0, use the following:
3155 .. parsed-literal::
3157 # on the host
3158 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
3159 # this host xterm should open in the guest X11 server
3160 xterm -display :1
3162 To redirect telnet connections from host port 5555 to telnet
3163 port on the guest, use the following:
3165 .. parsed-literal::
3167 # on the host
3168 |qemu_system| -nic user,hostfwd=tcp::5555-:23
3169 telnet localhost 5555
3171 Then when you use on the host ``telnet localhost 5555``, you
3172 connect to the guest telnet server.
3174 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command``
3175 Forward guest TCP connections to the IP address server on port
3176 port to the character device dev or to a program executed by
3177 cmd:command which gets spawned for each connection. This option
3178 can be given multiple times.
3180 You can either use a chardev directly and have that one used
3181 throughout QEMU's lifetime, like in the following example:
3183 .. parsed-literal::
3185 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
3186 # the guest accesses it
3187 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
3189 Or you can execute a command on every TCP connection established
3190 by the guest, so that QEMU behaves similar to an inetd process
3191 for that virtual server:
3193 .. parsed-literal::
3195 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
3196 # and connect the TCP stream to its stdin/stdout
3197 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
3199 ``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
3200 Configure a host TAP network backend with ID id.
3202 Use the network script file to configure it and the network script
3203 dfile to deconfigure it. If name is not provided, the OS
3204 automatically provides one. The default network configure script is
3205 ``/etc/qemu-ifup`` and the default network deconfigure script is
3206 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
3207 disable script execution.
3209 If running QEMU as an unprivileged user, use the network helper
3210 to configure the TAP interface and attach it to the bridge.
3211 The default network helper executable is
3212 ``/path/to/qemu-bridge-helper`` and the default bridge device is
3213 ``br0``.
3215 ``fd``\ =h can be used to specify the handle of an already opened
3216 host TAP interface.
3218 Examples:
3220 .. parsed-literal::
3222 #launch a QEMU instance with the default network script
3223 |qemu_system| linux.img -nic tap
3225 .. parsed-literal::
3227 #launch a QEMU instance with two NICs, each one connected
3228 #to a TAP device
3229 |qemu_system| linux.img \\
3230 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\
3231 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
3233 .. parsed-literal::
3235 #launch a QEMU instance with the default network helper to
3236 #connect a TAP device to bridge br0
3237 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3238 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
3240 ``-netdev bridge,id=id[,br=bridge][,helper=helper]``
3241 Connect a host TAP network interface to a host bridge device.
3243 Use the network helper helper to configure the TAP interface and
3244 attach it to the bridge. The default network helper executable is
3245 ``/path/to/qemu-bridge-helper`` and the default bridge device is
3246 ``br0``.
3248 Examples:
3250 .. parsed-literal::
3252 #launch a QEMU instance with the default network helper to
3253 #connect a TAP device to bridge br0
3254 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
3256 .. parsed-literal::
3258 #launch a QEMU instance with the default network helper to
3259 #connect a TAP device to bridge qemubr0
3260 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
3262 ``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
3263 This host network backend can be used to connect the guest's network
3264 to another QEMU virtual machine using a TCP socket connection. If
3265 ``listen`` is specified, QEMU waits for incoming connections on port
3266 (host is optional). ``connect`` is used to connect to another QEMU
3267 instance using the ``listen`` option. ``fd``\ =h specifies an
3268 already opened TCP socket.
3270 Example:
3272 .. parsed-literal::
3274 # launch a first QEMU instance
3275 |qemu_system| linux.img \\
3276 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3277 -netdev socket,id=n1,listen=:1234
3278 # connect the network of this instance to the network of the first instance
3279 |qemu_system| linux.img \\
3280 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
3281 -netdev socket,id=n2,connect=127.0.0.1:1234
3283 ``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]``
3284 Configure a socket host network backend to share the guest's network
3285 traffic with another QEMU virtual machines using a UDP multicast
3286 socket, effectively making a bus for every QEMU with same multicast
3287 address maddr and port. NOTES:
3289 1. Several QEMU can be running on different hosts and share same bus
3290 (assuming correct multicast setup for these hosts).
3292 2. mcast support is compatible with User Mode Linux (argument
3293 ``ethN=mcast``), see http://user-mode-linux.sf.net.
3295 3. Use ``fd=h`` to specify an already opened UDP multicast socket.
3297 Example:
3299 .. parsed-literal::
3301 # launch one QEMU instance
3302 |qemu_system| linux.img \\
3303 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3304 -netdev socket,id=n1,mcast=230.0.0.1:1234
3305 # launch another QEMU instance on same "bus"
3306 |qemu_system| linux.img \\
3307 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
3308 -netdev socket,id=n2,mcast=230.0.0.1:1234
3309 # launch yet another QEMU instance on same "bus"
3310 |qemu_system| linux.img \\
3311 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\
3312 -netdev socket,id=n3,mcast=230.0.0.1:1234
3314 Example (User Mode Linux compat.):
3316 .. parsed-literal::
3318 # launch QEMU instance (note mcast address selected is UML's default)
3319 |qemu_system| linux.img \\
3320 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3321 -netdev socket,id=n1,mcast=239.192.168.1:1102
3322 # launch UML
3323 /path/to/linux ubd0=/path/to/root_fs eth0=mcast
3325 Example (send packets from host's 1.2.3.4):
3327 .. parsed-literal::
3329 |qemu_system| linux.img \\
3330 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
3331 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
3333 ``-netdev l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6=on|off][,udp=on|off][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]``
3334 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
3335 is a popular protocol to transport Ethernet (and other Layer 2) data
3336 frames between two systems. It is present in routers, firewalls and
3337 the Linux kernel (from version 3.3 onwards).
3339 This transport allows a VM to communicate to another VM, router or
3340 firewall directly.
3342 ``src=srcaddr``
3343 source address (mandatory)
3345 ``dst=dstaddr``
3346 destination address (mandatory)
3348 ``udp``
3349 select udp encapsulation (default is ip).
3351 ``srcport=srcport``
3352 source udp port.
3354 ``dstport=dstport``
3355 destination udp port.
3357 ``ipv6``
3358 force v6, otherwise defaults to v4.
3360 ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
3361 Cookies are a weak form of security in the l2tpv3 specification.
3362 Their function is mostly to prevent misconfiguration. By default
3363 they are 32 bit.
3365 ``cookie64``
3366 Set cookie size to 64 bit instead of the default 32
3368 ``counter=off``
3369 Force a 'cut-down' L2TPv3 with no counter as in
3370 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
3372 ``pincounter=on``
3373 Work around broken counter handling in peer. This may also help
3374 on networks which have packet reorder.
3376 ``offset=offset``
3377 Add an extra offset between header and data
3379 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to
3380 the bridge br-lan on the remote Linux host 1.2.3.4:
3382 .. parsed-literal::
3384 # Setup tunnel on linux host using raw ip as encapsulation
3385 # on 1.2.3.4
3386 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\
3387 encap udp udp_sport 16384 udp_dport 16384
3388 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\
3389 0xFFFFFFFF peer_session_id 0xFFFFFFFF
3390 ifconfig vmtunnel0 mtu 1500
3391 ifconfig vmtunnel0 up
3392 brctl addif br-lan vmtunnel0
3395 # on 4.3.2.1
3396 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
3398 |qemu_system| linux.img -device e1000,netdev=n1 \\
3399 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
3401 ``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
3402 Configure VDE backend to connect to PORT n of a vde switch running
3403 on host and listening for incoming connections on socketpath. Use
3404 GROUP groupname and MODE octalmode to change default ownership and
3405 permissions for communication port. This option is only available if
3406 QEMU has been compiled with vde support enabled.
3408 Example:
3410 .. parsed-literal::
3412 # launch vde switch
3413 vde_switch -F -sock /tmp/myswitch
3414 # launch QEMU instance
3415 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch
3417 ``-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]``
3418 Configure AF_XDP backend to connect to a network interface 'name'
3419 using AF_XDP socket. A specific program attach mode for a default
3420 XDP program can be forced with 'mode', defaults to best-effort,
3421 where the likely most performant mode will be in use. Number of queues
3422 'n' should generally match the number or queues in the interface,
3423 defaults to 1. Traffic arriving on non-configured device queues will
3424 not be delivered to the network backend.
3426 .. parsed-literal::
3428 # set number of queues to 4
3429 ethtool -L eth0 combined 4
3430 # launch QEMU instance
3431 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3432 -netdev af-xdp,id=n1,ifname=eth0,queues=4
3434 'start-queue' option can be specified if a particular range of queues
3435 [m, m + n] should be in use. For example, this is may be necessary in
3436 order to use certain NICs in native mode. Kernel allows the driver to
3437 create a separate set of XDP queues on top of regular ones, and only
3438 these queues can be used for AF_XDP sockets. NICs that work this way
3439 may also require an additional traffic redirection with ethtool to these
3440 special queues.
3442 .. parsed-literal::
3444 # set number of queues to 1
3445 ethtool -L eth0 combined 1
3446 # redirect all the traffic to the second queue (id: 1)
3447 # note: drivers may require non-empty key/mask pair.
3448 ethtool -N eth0 flow-type ether \\
3449 dst 00:00:00:00:00:00 m FF:FF:FF:FF:FF:FE action 1
3450 ethtool -N eth0 flow-type ether \\
3451 dst 00:00:00:00:00:01 m FF:FF:FF:FF:FF:FE action 1
3452 # launch QEMU instance
3453 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3454 -netdev af-xdp,id=n1,ifname=eth0,queues=1,start-queue=1
3456 XDP program can also be loaded externally. In this case 'inhibit' option
3457 should be set to 'on' and 'sock-fds' provided with file descriptors for
3458 already open but not bound XDP sockets already added to a socket map for
3459 corresponding queues. One socket per queue.
3461 .. parsed-literal::
3463 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
3464 -netdev af-xdp,id=n1,ifname=eth0,queues=3,inhibit=on,sock-fds=15:16:17
3466 ``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
3467 Establish a vhost-user netdev, backed by a chardev id. The chardev
3468 should be a unix domain socket backed one. The vhost-user uses a
3469 specifically defined protocol to pass vhost ioctl replacement
3470 messages to an application on the other end of the socket. On
3471 non-MSIX guests, the feature can be forced with vhostforce. Use
3472 'queues=n' to specify the number of queues to be created for
3473 multiqueue vhost-user.
3475 Example:
3479 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
3480 -numa node,memdev=mem \
3481 -chardev socket,id=chr0,path=/path/to/socket \
3482 -netdev type=vhost-user,id=net0,chardev=chr0 \
3483 -device virtio-net-pci,netdev=net0
3485 ``-netdev vhost-vdpa[,vhostdev=/path/to/dev][,vhostfd=h]``
3486 Establish a vhost-vdpa netdev.
3488 vDPA device is a device that uses a datapath which complies with
3489 the virtio specifications with a vendor specific control path.
3490 vDPA devices can be both physically located on the hardware or
3491 emulated by software.
3493 ``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
3494 Create a hub port on the emulated hub with ID hubid.
3496 The hubport netdev lets you connect a NIC to a QEMU emulated hub
3497 instead of a single netdev. Alternatively, you can also connect the
3498 hubport to another netdev with ID nd by using the ``netdev=nd``
3499 option.
3501 ``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
3502 Legacy option to configure or create an on-board (or machine
3503 default) Network Interface Card(NIC) and connect it either to the
3504 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
3505 If model is omitted, then the default NIC model associated with the
3506 machine type is used. Note that the default NIC model may change in
3507 future QEMU releases, so it is highly recommended to always specify
3508 a model. Optionally, the MAC address can be changed to mac, the
3509 device address set to addr (PCI cards only), and a name can be
3510 assigned for use in monitor commands. Optionally, for PCI cards, you
3511 can specify the number v of MSI-X vectors that the card should have;
3512 this option currently only affects virtio cards; set v = 0 to
3513 disable MSI-X. If no ``-net`` option is specified, a single NIC is
3514 created. QEMU can emulate several different models of network card.
3515 Use ``-net nic,model=help`` for a list of available devices for your
3516 target.
3518 ``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
3519 Configure a host network backend (with the options corresponding to
3520 the same ``-netdev`` option) and connect it to the emulated hub 0
3521 (the default hub). Use name to specify the name of the hub port.
3522 ERST
3524 DEFHEADING()
3526 DEFHEADING(Character device options:)
3528 DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
3529 "-chardev help\n"
3530 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3531 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n"
3532 " [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n"
3533 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
3534 "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n"
3535 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n"
3536 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
3537 " [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n"
3538 " [,logfile=PATH][,logappend=on|off]\n"
3539 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3540 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
3541 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3542 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
3543 "-chardev file,id=id,path=path[,input-path=input-file][,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3544 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3545 #ifdef _WIN32
3546 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3547 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3548 #else
3549 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3550 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
3551 #endif
3552 #ifdef CONFIG_BRLAPI
3553 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3554 #endif
3555 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
3556 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
3557 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3558 #endif
3559 #if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
3560 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3561 #endif
3562 #if defined(CONFIG_SPICE)
3563 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3564 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3565 #endif
3566 , QEMU_ARCH_ALL
3569 SRST
3570 The general form of a character device option is:
3572 ``-chardev backend,id=id[,mux=on|off][,options]``
3573 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
3574 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
3575 ``pty``, ``stdio``, ``braille``, ``parallel``,
3576 ``spicevmc``, ``spiceport``. The specific backend will determine the
3577 applicable options.
3579 Use ``-chardev help`` to print all available chardev backend types.
3581 All devices must have an id, which can be any string up to 127
3582 characters long. It is used to uniquely identify this device in
3583 other command line directives.
3585 A character device may be used in multiplexing mode by multiple
3586 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
3587 a "1:N" device, and here the "1" end is your specified chardev
3588 backend, and the "N" end is the various parts of QEMU that can talk
3589 to a chardev. If you create a chardev with ``id=myid`` and
3590 ``mux=on``, QEMU will create a multiplexer with your specified ID,
3591 and you can then configure multiple front ends to use that chardev
3592 ID for their input/output. Up to four different front ends can be
3593 connected to a single multiplexed chardev. (Without multiplexing
3594 enabled, a chardev can only be used by a single front end.) For
3595 instance you could use this to allow a single stdio chardev to be
3596 used by two serial ports and the QEMU monitor:
3600 -chardev stdio,mux=on,id=char0 \
3601 -mon chardev=char0,mode=readline \
3602 -serial chardev:char0 \
3603 -serial chardev:char0
3605 You can have more than one multiplexer in a system configuration;
3606 for instance you could have a TCP port multiplexed between UART 0
3607 and UART 1, and stdio multiplexed between the QEMU monitor and a
3608 parallel port:
3612 -chardev stdio,mux=on,id=char0 \
3613 -mon chardev=char0,mode=readline \
3614 -parallel chardev:char0 \
3615 -chardev tcp,...,mux=on,id=char1 \
3616 -serial chardev:char1 \
3617 -serial chardev:char1
3619 When you're using a multiplexed character device, some escape
3620 sequences are interpreted in the input. See the chapter about
3621 :ref:`keys in the character backend multiplexer` in the
3622 System Emulation Users Guide for more details.
3624 Note that some other command line options may implicitly create
3625 multiplexed character backends; for instance ``-serial mon:stdio``
3626 creates a multiplexed stdio backend connected to the serial port and
3627 the QEMU monitor, and ``-nographic`` also multiplexes the console
3628 and the monitor to stdio.
3630 There is currently no support for multiplexing in the other
3631 direction (where a single QEMU front end takes input and output from
3632 multiple chardevs).
3634 Every backend supports the ``logfile`` option, which supplies the
3635 path to a file to record all data transmitted via the backend. The
3636 ``logappend`` option controls whether the log file will be truncated
3637 or appended to when opened.
3639 The available backends are:
3641 ``-chardev null,id=id``
3642 A void device. This device will not emit any data, and will drop any
3643 data it receives. The null backend does not take any options.
3645 ``-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]``
3646 Create a two-way stream socket, which can be either a TCP or a unix
3647 socket. A unix socket will be created if ``path`` is specified.
3648 Behaviour is undefined if TCP options are specified for a unix
3649 socket.
3651 ``server=on|off`` specifies that the socket shall be a listening socket.
3653 ``wait=on|off`` specifies that QEMU should not block waiting for a client
3654 to connect to a listening socket.
3656 ``telnet=on|off`` specifies that traffic on the socket should interpret
3657 telnet escape sequences.
3659 ``websocket=on|off`` specifies that the socket uses WebSocket protocol for
3660 communication.
3662 ``reconnect`` sets the timeout for reconnecting on non-server
3663 sockets when the remote end goes away. qemu will delay this many
3664 seconds and then attempt to reconnect. Zero disables reconnecting,
3665 and is the default.
3667 ``tls-creds`` requests enablement of the TLS protocol for
3668 encryption, and specifies the id of the TLS credentials to use for
3669 the handshake. The credentials must be previously created with the
3670 ``-object tls-creds`` argument.
3672 ``tls-auth`` provides the ID of the QAuthZ authorization object
3673 against which the client's x509 distinguished name will be
3674 validated. This object is only resolved at time of use, so can be
3675 deleted and recreated on the fly while the chardev server is active.
3676 If missing, it will default to denying access.
3678 TCP and unix socket options are given below:
3680 ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]``
3681 ``host`` for a listening socket specifies the local address to
3682 be bound. For a connecting socket species the remote host to
3683 connect to. ``host`` is optional for listening sockets. If not
3684 specified it defaults to ``0.0.0.0``.
3686 ``port`` for a listening socket specifies the local port to be
3687 bound. For a connecting socket specifies the port on the remote
3688 host to connect to. ``port`` can be given as either a port
3689 number or a service name. ``port`` is required.
3691 ``to`` is only relevant to listening sockets. If it is
3692 specified, and ``port`` cannot be bound, QEMU will attempt to
3693 bind to subsequent ports up to and including ``to`` until it
3694 succeeds. ``to`` must be specified as a port number.
3696 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4
3697 or IPv6 must be used. If neither is specified the socket may
3698 use either protocol.
3700 ``nodelay=on|off`` disables the Nagle algorithm.
3702 ``unix options: path=path[,abstract=on|off][,tight=on|off]``
3703 ``path`` specifies the local path of the unix socket. ``path``
3704 is required.
3705 ``abstract=on|off`` specifies the use of the abstract socket namespace,
3706 rather than the filesystem. Optional, defaults to false.
3707 ``tight=on|off`` sets the socket length of abstract sockets to their minimum,
3708 rather than the full sun_path length. Optional, defaults to true.
3710 ``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]``
3711 Sends all traffic from the guest to a remote host over UDP.
3713 ``host`` specifies the remote host to connect to. If not specified
3714 it defaults to ``localhost``.
3716 ``port`` specifies the port on the remote host to connect to.
3717 ``port`` is required.
3719 ``localaddr`` specifies the local address to bind to. If not
3720 specified it defaults to ``0.0.0.0``.
3722 ``localport`` specifies the local port to bind to. If not specified
3723 any available local port will be used.
3725 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used.
3726 If neither is specified the device may use either protocol.
3728 ``-chardev msmouse,id=id``
3729 Forward QEMU's emulated msmouse events to the guest. ``msmouse``
3730 does not take any options.
3732 ``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
3733 Connect to a QEMU text console. ``vc`` may optionally be given a
3734 specific size.
3736 ``width`` and ``height`` specify the width and height respectively
3737 of the console, in pixels.
3739 ``cols`` and ``rows`` specify that the console be sized to fit a
3740 text console with the given dimensions.
3742 ``-chardev ringbuf,id=id[,size=size]``
3743 Create a ring buffer with fixed size ``size``. size must be a power
3744 of two and defaults to ``64K``.
3746 ``-chardev file,id=id,path=path[,input-path=input-path]``
3747 Log all traffic received from the guest to a file.
3749 ``path`` specifies the path of the file to be opened. This file will
3750 be created if it does not already exist, and overwritten if it does.
3751 ``path`` is required.
3753 If ``input-path`` is specified, this is the path of a second file
3754 which will be used for input. If ``input-path`` is not specified,
3755 no input will be available from the chardev.
3757 Note that ``input-path`` is not supported on Windows hosts.
3759 ``-chardev pipe,id=id,path=path``
3760 Create a two-way connection to the guest. The behaviour differs
3761 slightly between Windows hosts and other hosts:
3763 On Windows, a single duplex pipe will be created at
3764 ``\\.pipe\path``.
3766 On other hosts, 2 pipes will be created called ``path.in`` and
3767 ``path.out``. Data written to ``path.in`` will be received by the
3768 guest. Data written by the guest can be read from ``path.out``. QEMU
3769 will not create these fifos, and requires them to be present.
3771 ``path`` forms part of the pipe path as described above. ``path`` is
3772 required.
3774 ``-chardev console,id=id``
3775 Send traffic from the guest to QEMU's standard output. ``console``
3776 does not take any options.
3778 ``console`` is only available on Windows hosts.
3780 ``-chardev serial,id=id,path=path``
3781 Send traffic from the guest to a serial device on the host.
3783 On Unix hosts serial will actually accept any tty device, not only
3784 serial lines.
3786 ``path`` specifies the name of the serial device to open.
3788 ``-chardev pty,id=id``
3789 Create a new pseudo-terminal on the host and connect to it. ``pty``
3790 does not take any options.
3792 ``pty`` is not available on Windows hosts.
3794 ``-chardev stdio,id=id[,signal=on|off]``
3795 Connect to standard input and standard output of the QEMU process.
3797 ``signal`` controls if signals are enabled on the terminal, that
3798 includes exiting QEMU with the key sequence Control-c. This option
3799 is enabled by default, use ``signal=off`` to disable it.
3801 ``-chardev braille,id=id``
3802 Connect to a local BrlAPI server. ``braille`` does not take any
3803 options.
3805 ``-chardev parallel,id=id,path=path``
3807 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
3808 hosts.
3810 Connect to a local parallel port.
3812 ``path`` specifies the path to the parallel port device. ``path`` is
3813 required.
3815 ``-chardev spicevmc,id=id,debug=debug,name=name``
3816 ``spicevmc`` is only available when spice support is built in.
3818 ``debug`` debug level for spicevmc
3820 ``name`` name of spice channel to connect to
3822 Connect to a spice virtual machine channel, such as vdiport.
3824 ``-chardev spiceport,id=id,debug=debug,name=name``
3825 ``spiceport`` is only available when spice support is built in.
3827 ``debug`` debug level for spicevmc
3829 ``name`` name of spice port to connect to
3831 Connect to a spice port, allowing a Spice client to handle the
3832 traffic identified by a name (preferably a fqdn).
3833 ERST
3835 DEFHEADING()
3837 #ifdef CONFIG_TPM
3838 DEFHEADING(TPM device options:)
3840 DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3841 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3842 " use path to provide path to a character device; default is /dev/tpm0\n"
3843 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
3844 " not provided it will be searched for in /sys/class/misc/tpm?/device\n"
3845 "-tpmdev emulator,id=id,chardev=dev\n"
3846 " configure the TPM device using chardev backend\n",
3847 QEMU_ARCH_ALL)
3848 SRST
3849 The general form of a TPM device option is:
3851 ``-tpmdev backend,id=id[,options]``
3852 The specific backend type will determine the applicable options. The
3853 ``-tpmdev`` option creates the TPM backend and requires a
3854 ``-device`` option that specifies the TPM frontend interface model.
3856 Use ``-tpmdev help`` to print all available TPM backend types.
3858 The available backends are:
3860 ``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
3861 (Linux-host only) Enable access to the host's TPM using the
3862 passthrough driver.
3864 ``path`` specifies the path to the host's TPM device, i.e., on a
3865 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
3866 default ``/dev/tpm0`` is used.
3868 ``cancel-path`` specifies the path to the host TPM device's sysfs
3869 entry allowing for cancellation of an ongoing TPM command.
3870 ``cancel-path`` is optional and by default QEMU will search for the
3871 sysfs entry to use.
3873 Some notes about using the host's TPM with the passthrough driver:
3875 The TPM device accessed by the passthrough driver must not be used
3876 by any other application on the host.
3878 Since the host's firmware (BIOS/UEFI) has already initialized the
3879 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
3880 the TPM again and may therefore not show a TPM-specific menu that
3881 would otherwise allow the user to configure the TPM, e.g., allow the
3882 user to enable/disable or activate/deactivate the TPM. Further, if
3883 TPM ownership is released from within a VM then the host's TPM will
3884 get disabled and deactivated. To enable and activate the TPM again
3885 afterwards, the host has to be rebooted and the user is required to
3886 enter the firmware's menu to enable and activate the TPM. If the TPM
3887 is left disabled and/or deactivated most TPM commands will fail.
3889 To create a passthrough TPM use the following two options:
3893 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3895 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
3896 ``tpmdev=tpm0`` in the device option.
3898 ``-tpmdev emulator,id=id,chardev=dev``
3899 (Linux-host only) Enable access to a TPM emulator using Unix domain
3900 socket based chardev backend.
3902 ``chardev`` specifies the unique ID of a character device backend
3903 that provides connection to the software TPM server.
3905 To create a TPM emulator backend device with chardev socket backend:
3909 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3910 ERST
3912 DEFHEADING()
3914 #endif
3916 DEFHEADING(Boot Image or Kernel specific:)
3917 SRST
3918 There are broadly 4 ways you can boot a system with QEMU.
3920 - specify a firmware and let it control finding a kernel
3921 - specify a firmware and pass a hint to the kernel to boot
3922 - direct kernel image boot
3923 - manually load files into the guest's address space
3925 The third method is useful for quickly testing kernels but as there is
3926 no firmware to pass configuration information to the kernel the
3927 hardware must either be probeable, the kernel built for the exact
3928 configuration or passed some configuration data (e.g. a DTB blob)
3929 which tells the kernel what drivers it needs. This exact details are
3930 often hardware specific.
3932 The final method is the most generic way of loading images into the
3933 guest address space and used mostly for ``bare metal`` type
3934 development where the reset vectors of the processor are taken into
3935 account.
3937 ERST
3939 SRST
3941 For x86 machines and some other architectures ``-bios`` will generally
3942 do the right thing with whatever it is given. For other machines the
3943 more strict ``-pflash`` option needs an image that is sized for the
3944 flash device for the given machine type.
3946 Please see the :ref:`system-targets-ref` section of the manual for
3947 more detailed documentation.
3949 ERST
3951 DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
3952 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL)
3953 SRST
3954 ``-bios file``
3955 Set the filename for the BIOS.
3956 ERST
3958 DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
3959 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
3960 SRST
3961 ``-pflash file``
3962 Use file as a parallel flash image.
3963 ERST
3965 SRST
3967 The kernel options were designed to work with Linux kernels although
3968 other things (like hypervisors) can be packaged up as a kernel
3969 executable image. The exact format of a executable image is usually
3970 architecture specific.
3972 The way in which the kernel is started (what address it is loaded at,
3973 what if any information is passed to it via CPU registers, the state
3974 of the hardware when it is started, and so on) is also architecture
3975 specific. Typically it follows the specification laid down by the
3976 Linux kernel for how kernels for that architecture must be started.
3978 ERST
3980 DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
3981 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
3982 SRST
3983 ``-kernel bzImage``
3984 Use bzImage as kernel image. The kernel can be either a Linux kernel
3985 or in multiboot format.
3986 ERST
3988 DEF("append", HAS_ARG, QEMU_OPTION_append, \
3989 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
3990 SRST
3991 ``-append cmdline``
3992 Use cmdline as kernel command line
3993 ERST
3995 DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
3996 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
3997 SRST
3999 ``-initrd file``
4000 Use file as initial ram disk.
4002 ``-initrd "file1 arg=foo,file2"``
4003 This syntax is only available with multiboot.
4005 Use file1 and file2 as modules and pass ``arg=foo`` as parameter to the
4006 first module. Commas can be provided in module parameters by doubling
4007 them on the command line to escape them:
4009 ``-initrd "bzImage earlyprintk=xen,,keep root=/dev/xvda1,initrd.img"``
4010 Multiboot only. Use bzImage as the first module with
4011 "``earlyprintk=xen,keep root=/dev/xvda1``" as its command line,
4012 and initrd.img as the second module.
4014 ERST
4016 DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
4017 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL)
4018 SRST
4019 ``-dtb file``
4020 Use file as a device tree binary (dtb) image and pass it to the
4021 kernel on boot.
4022 ERST
4024 SRST
4026 Finally you can also manually load images directly into the address
4027 space of the guest. This is most useful for developers who already
4028 know the layout of their guest and take care to ensure something sane
4029 will happen when the reset vector executes.
4031 The generic loader can be invoked by using the loader device:
4033 ``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]``
4035 there is also the guest loader which operates in a similar way but
4036 tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where
4037 the guest image is:
4039 ``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]``
4041 ERST
4043 DEFHEADING()
4045 DEFHEADING(Debug/Expert options:)
4047 DEF("compat", HAS_ARG, QEMU_OPTION_compat,
4048 "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n"
4049 " Policy for handling deprecated management interfaces\n"
4050 "-compat [unstable-input=accept|reject|crash][,unstable-output=accept|hide]\n"
4051 " Policy for handling unstable management interfaces\n",
4052 QEMU_ARCH_ALL)
4053 SRST
4054 ``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]``
4055 Set policy for handling deprecated management interfaces (experimental):
4057 ``deprecated-input=accept`` (default)
4058 Accept deprecated commands and arguments
4059 ``deprecated-input=reject``
4060 Reject deprecated commands and arguments
4061 ``deprecated-input=crash``
4062 Crash on deprecated commands and arguments
4063 ``deprecated-output=accept`` (default)
4064 Emit deprecated command results and events
4065 ``deprecated-output=hide``
4066 Suppress deprecated command results and events
4068 Limitation: covers only syntactic aspects of QMP.
4070 ``-compat [unstable-input=@var{input-policy}][,unstable-output=@var{output-policy}]``
4071 Set policy for handling unstable management interfaces (experimental):
4073 ``unstable-input=accept`` (default)
4074 Accept unstable commands and arguments
4075 ``unstable-input=reject``
4076 Reject unstable commands and arguments
4077 ``unstable-input=crash``
4078 Crash on unstable commands and arguments
4079 ``unstable-output=accept`` (default)
4080 Emit unstable command results and events
4081 ``unstable-output=hide``
4082 Suppress unstable command results and events
4084 Limitation: covers only syntactic aspects of QMP.
4085 ERST
4087 DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
4088 "-fw_cfg [name=]<name>,file=<file>\n"
4089 " add named fw_cfg entry with contents from file\n"
4090 "-fw_cfg [name=]<name>,string=<str>\n"
4091 " add named fw_cfg entry with contents from string\n",
4092 QEMU_ARCH_ALL)
4093 SRST
4094 ``-fw_cfg [name=]name,file=file``
4095 Add named fw\_cfg entry with contents from file file.
4096 If the filename contains comma, you must double it (for instance,
4097 "file=my,,file" to use file "my,file").
4099 ``-fw_cfg [name=]name,string=str``
4100 Add named fw\_cfg entry with contents from string str.
4101 If the string contains comma, you must double it (for instance,
4102 "string=my,,string" to use file "my,string").
4104 The terminating NUL character of the contents of str will not be
4105 included as part of the fw\_cfg item data. To insert contents with
4106 embedded NUL characters, you have to use the file parameter.
4108 The fw\_cfg entries are passed by QEMU through to the guest.
4110 Example:
4114 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
4116 creates an fw\_cfg entry named opt/com.mycompany/blob with contents
4117 from ./my\_blob.bin.
4118 ERST
4120 DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
4121 "-serial dev redirect the serial port to char device 'dev'\n",
4122 QEMU_ARCH_ALL)
4123 SRST
4124 ``-serial dev``
4125 Redirect the virtual serial port to host character device dev. The
4126 default device is ``vc`` in graphical mode and ``stdio`` in non
4127 graphical mode.
4129 This option can be used several times to simulate up to 4 serial
4130 ports.
4132 Use ``-serial none`` to disable all serial ports.
4134 Available character devices are:
4136 ``vc[:WxH]``
4137 Virtual console. Optionally, a width and height can be given in
4138 pixel with
4142 vc:800x600
4144 It is also possible to specify width or height in characters:
4148 vc:80Cx24C
4150 ``pty``
4151 [Linux only] Pseudo TTY (a new PTY is automatically allocated)
4153 ``none``
4154 No device is allocated.
4156 ``null``
4157 void device
4159 ``chardev:id``
4160 Use a named character device defined with the ``-chardev``
4161 option.
4163 ``/dev/XXX``
4164 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
4165 port parameters are set according to the emulated ones.
4167 ``/dev/parportN``
4168 [Linux only, parallel port only] Use host parallel port N.
4169 Currently SPP and EPP parallel port features can be used.
4171 ``file:filename``
4172 Write output to filename. No character can be read.
4174 ``stdio``
4175 [Unix only] standard input/output
4177 ``pipe:filename``
4178 name pipe filename
4180 ``COMn``
4181 [Windows only] Use host serial port n
4183 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
4184 This implements UDP Net Console. When remote\_host or src\_ip
4185 are not specified they default to ``0.0.0.0``. When not using a
4186 specified src\_port a random port is automatically chosen.
4188 If you just want a simple readonly console you can use
4189 ``netcat`` or ``nc``, by starting QEMU with:
4190 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
4191 QEMU writes something to that port it will appear in the
4192 netconsole session.
4194 If you plan to send characters back via netconsole or you want
4195 to stop and start QEMU a lot of times, you should have QEMU use
4196 the same source port each time by using something like ``-serial
4197 udp::4555@:4556`` to QEMU. Another approach is to use a patched
4198 version of netcat which can listen to a TCP port and send and
4199 receive characters via udp. If you have a patched version of
4200 netcat which activates telnet remote echo and single char
4201 transfer, then you can use the following options to set up a
4202 netcat redirector to allow telnet on port 5555 to access the
4203 QEMU port.
4205 ``QEMU Options:``
4206 -serial udp::4555@:4556
4208 ``netcat options:``
4209 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
4211 ``telnet options:``
4212 localhost 5555
4214 ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]``
4215 The TCP Net Console has two modes of operation. It can send the
4216 serial I/O to a location or wait for a connection from a
4217 location. By default the TCP Net Console is sent to host at the
4218 port. If you use the ``server=on`` option QEMU will wait for a client
4219 socket application to connect to the port before continuing,
4220 unless the ``wait=on|off`` option was specified. The ``nodelay=on|off``
4221 option disables the Nagle buffering algorithm. The ``reconnect=on``
4222 option only applies if ``server=no`` is set, if the connection goes
4223 down it will attempt to reconnect at the given interval. If host
4224 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a
4225 time is accepted. You can use ``telnet=on`` to connect to the
4226 corresponding character device.
4228 ``Example to send tcp console to 192.168.0.2 port 4444``
4229 -serial tcp:192.168.0.2:4444
4231 ``Example to listen and wait on port 4444 for connection``
4232 -serial tcp::4444,server=on
4234 ``Example to not wait and listen on ip 192.168.0.100 port 4444``
4235 -serial tcp:192.168.0.100:4444,server=on,wait=off
4237 ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]``
4238 The telnet protocol is used instead of raw tcp sockets. The
4239 options work the same as if you had specified ``-serial tcp``.
4240 The difference is that the port acts like a telnet server or
4241 client using telnet option negotiation. This will also allow you
4242 to send the MAGIC\_SYSRQ sequence if you use a telnet that
4243 supports sending the break sequence. Typically in unix telnet
4244 you do it with Control-] and then type "send break" followed by
4245 pressing the enter key.
4247 ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]``
4248 The WebSocket protocol is used instead of raw tcp socket. The
4249 port acts as a WebSocket server. Client mode is not supported.
4251 ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]``
4252 A unix domain socket is used instead of a tcp socket. The option
4253 works the same as if you had specified ``-serial tcp`` except
4254 the unix domain socket path is used for connections.
4256 ``mon:dev_string``
4257 This is a special option to allow the monitor to be multiplexed
4258 onto another serial port. The monitor is accessed with key
4259 sequence of Control-a and then pressing c. dev\_string should be
4260 any one of the serial devices specified above. An example to
4261 multiplex the monitor onto a telnet server listening on port
4262 4444 would be:
4264 ``-serial mon:telnet::4444,server=on,wait=off``
4266 When the monitor is multiplexed to stdio in this way, Ctrl+C
4267 will not terminate QEMU any more but will be passed to the guest
4268 instead.
4270 ``braille``
4271 Braille device. This will use BrlAPI to display the braille
4272 output on a real or fake device.
4274 ``msmouse``
4275 Three button serial mouse. Configure the guest to use Microsoft
4276 protocol.
4277 ERST
4279 DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
4280 "-parallel dev redirect the parallel port to char device 'dev'\n",
4281 QEMU_ARCH_ALL)
4282 SRST
4283 ``-parallel dev``
4284 Redirect the virtual parallel port to host device dev (same devices
4285 as the serial port). On Linux hosts, ``/dev/parportN`` can be used
4286 to use hardware devices connected on the corresponding host parallel
4287 port.
4289 This option can be used several times to simulate up to 3 parallel
4290 ports.
4292 Use ``-parallel none`` to disable all parallel ports.
4293 ERST
4295 DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
4296 "-monitor dev redirect the monitor to char device 'dev'\n",
4297 QEMU_ARCH_ALL)
4298 SRST
4299 ``-monitor dev``
4300 Redirect the monitor to host device dev (same devices as the serial
4301 port). The default device is ``vc`` in graphical mode and ``stdio``
4302 in non graphical mode. Use ``-monitor none`` to disable the default
4303 monitor.
4304 ERST
4305 DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
4306 "-qmp dev like -monitor but opens in 'control' mode\n",
4307 QEMU_ARCH_ALL)
4308 SRST
4309 ``-qmp dev``
4310 Like ``-monitor`` but opens in 'control' mode. For example, to make
4311 QMP available on localhost port 4444::
4313 -qmp tcp:localhost:4444,server=on,wait=off
4315 Not all options are configurable via this syntax; for maximum
4316 flexibility use the ``-mon`` option and an accompanying ``-chardev``.
4318 ERST
4319 DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
4320 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
4321 QEMU_ARCH_ALL)
4322 SRST
4323 ``-qmp-pretty dev``
4324 Like ``-qmp`` but uses pretty JSON formatting.
4325 ERST
4327 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
4328 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
4329 SRST
4330 ``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
4331 Set up a monitor connected to the chardev ``name``.
4332 QEMU supports two monitors: the Human Monitor Protocol
4333 (HMP; for human interaction), and the QEMU Monitor Protocol
4334 (QMP; a JSON RPC-style protocol).
4335 The default is HMP; ``mode=control`` selects QMP instead.
4336 ``pretty`` is only valid when ``mode=control``,
4337 turning on JSON pretty printing to ease
4338 human reading and debugging.
4340 For example::
4342 -chardev socket,id=mon1,host=localhost,port=4444,server=on,wait=off \
4343 -mon chardev=mon1,mode=control,pretty=on
4345 enables the QMP monitor on localhost port 4444 with pretty-printing.
4346 ERST
4348 DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
4349 "-debugcon dev redirect the debug console to char device 'dev'\n",
4350 QEMU_ARCH_ALL)
4351 SRST
4352 ``-debugcon dev``
4353 Redirect the debug console to host device dev (same devices as the
4354 serial port). The debug console is an I/O port which is typically
4355 port 0xe9; writing to that I/O port sends output to this device. The
4356 default device is ``vc`` in graphical mode and ``stdio`` in non
4357 graphical mode.
4358 ERST
4360 DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
4361 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL)
4362 SRST
4363 ``-pidfile file``
4364 Store the QEMU process PID in file. It is useful if you launch QEMU
4365 from a script.
4366 ERST
4368 DEF("preconfig", 0, QEMU_OPTION_preconfig, \
4369 "--preconfig pause QEMU before machine is initialized (experimental)\n",
4370 QEMU_ARCH_ALL)
4371 SRST
4372 ``--preconfig``
4373 Pause QEMU for interactive configuration before the machine is
4374 created, which allows querying and configuring properties that will
4375 affect machine initialization. Use QMP command 'x-exit-preconfig' to
4376 exit the preconfig state and move to the next state (i.e. run guest
4377 if -S isn't used or pause the second time if -S is used). This
4378 option is experimental.
4379 ERST
4381 DEF("S", 0, QEMU_OPTION_S, \
4382 "-S freeze CPU at startup (use 'c' to start execution)\n",
4383 QEMU_ARCH_ALL)
4384 SRST
4385 ``-S``
4386 Do not start CPU at startup (you must type 'c' in the monitor).
4387 ERST
4389 DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
4390 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
4391 " run qemu with overcommit hints\n"
4392 " mem-lock=on|off controls memory lock support (default: off)\n"
4393 " cpu-pm=on|off controls cpu power management (default: off)\n",
4394 QEMU_ARCH_ALL)
4395 SRST
4396 ``-overcommit mem-lock=on|off``
4398 ``-overcommit cpu-pm=on|off``
4399 Run qemu with hints about host resource overcommit. The default is
4400 to assume that host overcommits all resources.
4402 Locking qemu and guest memory can be enabled via ``mem-lock=on``
4403 (disabled by default). This works when host memory is not
4404 overcommitted and reduces the worst-case latency for guest.
4406 Guest ability to manage power state of host cpus (increasing latency
4407 for other processes on the same host cpu, but decreasing latency for
4408 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
4409 works best when host CPU is not overcommitted. When used, host
4410 estimates of CPU cycle and power utilization will be incorrect, not
4411 taking into account guest idle time.
4412 ERST
4414 DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
4415 "-gdb dev accept gdb connection on 'dev'. (QEMU defaults to starting\n"
4416 " the guest without waiting for gdb to connect; use -S too\n"
4417 " if you want it to not start execution.)\n",
4418 QEMU_ARCH_ALL)
4419 SRST
4420 ``-gdb dev``
4421 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter
4422 in the System Emulation Users Guide). Note that this option does not pause QEMU
4423 execution -- if you want QEMU to not start the guest until you
4424 connect with gdb and issue a ``continue`` command, you will need to
4425 also pass the ``-S`` option to QEMU.
4427 The most usual configuration is to listen on a local TCP socket::
4429 -gdb tcp::3117
4431 but you can specify other backends; UDP, pseudo TTY, or even stdio
4432 are all reasonable use cases. For example, a stdio connection
4433 allows you to start QEMU from within gdb and establish the
4434 connection via a pipe:
4436 .. parsed-literal::
4438 (gdb) target remote | exec |qemu_system| -gdb stdio ...
4439 ERST
4441 DEF("s", 0, QEMU_OPTION_s, \
4442 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
4443 QEMU_ARCH_ALL)
4444 SRST
4445 ``-s``
4446 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
4447 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide).
4448 ERST
4450 DEF("d", HAS_ARG, QEMU_OPTION_d, \
4451 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n",
4452 QEMU_ARCH_ALL)
4453 SRST
4454 ``-d item1[,...]``
4455 Enable logging of specified items. Use '-d help' for a list of log
4456 items.
4457 ERST
4459 DEF("D", HAS_ARG, QEMU_OPTION_D, \
4460 "-D logfile output log to logfile (default stderr)\n",
4461 QEMU_ARCH_ALL)
4462 SRST
4463 ``-D logfile``
4464 Output log in logfile instead of to stderr
4465 ERST
4467 DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
4468 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
4469 QEMU_ARCH_ALL)
4470 SRST
4471 ``-dfilter range1[,...]``
4472 Filter debug output to that relevant to a range of target addresses.
4473 The filter spec can be either start+size, start-size or start..end
4474 where start end and size are the addresses and sizes required. For
4475 example:
4479 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
4481 Will dump output for any code in the 0x1000 sized block starting at
4482 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
4483 another 0x1000 sized block starting at 0xffffffc00005f000.
4484 ERST
4486 DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
4487 "-seed number seed the pseudo-random number generator\n",
4488 QEMU_ARCH_ALL)
4489 SRST
4490 ``-seed number``
4491 Force the guest to use a deterministic pseudo-random number
4492 generator, seeded with number. This does not affect crypto routines
4493 within the host.
4494 ERST
4496 DEF("L", HAS_ARG, QEMU_OPTION_L, \
4497 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n",
4498 QEMU_ARCH_ALL)
4499 SRST
4500 ``-L path``
4501 Set the directory for the BIOS, VGA BIOS and keymaps.
4503 To list all the data directories, use ``-L help``.
4504 ERST
4506 DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
4507 "-enable-kvm enable KVM full virtualization support\n",
4508 QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC |
4509 QEMU_ARCH_RISCV | QEMU_ARCH_S390X)
4510 SRST
4511 ``-enable-kvm``
4512 Enable KVM full virtualization support. This option is only
4513 available if KVM support is enabled when compiling.
4514 ERST
4516 DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
4517 "-xen-domid id specify xen guest domain id\n",
4518 QEMU_ARCH_ARM | QEMU_ARCH_I386)
4519 DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
4520 "-xen-attach attach to existing xen domain\n"
4521 " libxl will use this when starting QEMU\n",
4522 QEMU_ARCH_ARM | QEMU_ARCH_I386)
4523 DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
4524 "-xen-domid-restrict restrict set of available xen operations\n"
4525 " to specified domain id. (Does not affect\n"
4526 " xenpv machine type).\n",
4527 QEMU_ARCH_ARM | QEMU_ARCH_I386)
4528 SRST
4529 ``-xen-domid id``
4530 Specify xen guest domain id (XEN only).
4532 ``-xen-attach``
4533 Attach to existing xen domain. libxl will use this when starting
4534 QEMU (XEN only). Restrict set of available xen operations to
4535 specified domain id (XEN only).
4536 ERST
4538 DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
4539 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL)
4540 SRST
4541 ``-no-reboot``
4542 Exit instead of rebooting.
4543 ERST
4545 DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
4546 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL)
4547 SRST
4548 ``-no-shutdown``
4549 Don't exit QEMU on guest shutdown, but instead only stop the
4550 emulation. This allows for instance switching to monitor to commit
4551 changes to the disk image.
4552 ERST
4554 DEF("action", HAS_ARG, QEMU_OPTION_action,
4555 "-action reboot=reset|shutdown\n"
4556 " action when guest reboots [default=reset]\n"
4557 "-action shutdown=poweroff|pause\n"
4558 " action when guest shuts down [default=poweroff]\n"
4559 "-action panic=pause|shutdown|exit-failure|none\n"
4560 " action when guest panics [default=shutdown]\n"
4561 "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
4562 " action when watchdog fires [default=reset]\n",
4563 QEMU_ARCH_ALL)
4564 SRST
4565 ``-action event=action``
4566 The action parameter serves to modify QEMU's default behavior when
4567 certain guest events occur. It provides a generic method for specifying the
4568 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown``
4569 parameters.
4571 Examples:
4573 ``-action panic=none``
4574 ``-action reboot=shutdown,shutdown=pause``
4575 ``-device i6300esb -action watchdog=pause``
4577 ERST
4579 DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
4580 "-loadvm [tag|id]\n" \
4581 " start right away with a saved state (loadvm in monitor)\n",
4582 QEMU_ARCH_ALL)
4583 SRST
4584 ``-loadvm file``
4585 Start right away with a saved state (``loadvm`` in monitor)
4586 ERST
4588 #ifndef _WIN32
4589 DEF("daemonize", 0, QEMU_OPTION_daemonize, \
4590 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
4591 #endif
4592 SRST
4593 ``-daemonize``
4594 Daemonize the QEMU process after initialization. QEMU will not
4595 detach from standard IO until it is ready to receive connections on
4596 any of its devices. This option is a useful way for external
4597 programs to launch QEMU without having to cope with initialization
4598 race conditions.
4599 ERST
4601 DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
4602 "-option-rom rom load a file, rom, into the option ROM space\n",
4603 QEMU_ARCH_ALL)
4604 SRST
4605 ``-option-rom file``
4606 Load the contents of file as an option ROM. This option is useful to
4607 load things like EtherBoot.
4608 ERST
4610 DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
4611 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
4612 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
4613 QEMU_ARCH_ALL)
4615 SRST
4616 ``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
4617 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
4618 the current UTC or local time, respectively. ``localtime`` is
4619 required for correct date in MS-DOS or Windows. To start at a
4620 specific point in time, provide datetime in the format
4621 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.
4623 By default the RTC is driven by the host system time. This allows
4624 using of the RTC as accurate reference clock inside the guest,
4625 specifically if the host time is smoothly following an accurate
4626 external reference clock, e.g. via NTP. If you want to isolate the
4627 guest time from the host, you can set ``clock`` to ``rt`` instead,
4628 which provides a host monotonic clock if host support it. To even
4629 prevent the RTC from progressing during suspension, you can set
4630 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
4631 recommended especially in icount mode in order to preserve
4632 determinism; however, note that in icount mode the speed of the
4633 virtual clock is variable and can in general differ from the host
4634 clock.
4636 Enable ``driftfix`` (i386 targets only) if you experience time drift
4637 problems, specifically with Windows' ACPI HAL. This option will try
4638 to figure out how many timer interrupts were not processed by the
4639 Windows guest and will re-inject them.
4640 ERST
4642 DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
4643 "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \
4644 " enable virtual instruction counter with 2^N clock ticks per\n" \
4645 " instruction, enable aligning the host and virtual clocks\n" \
4646 " or disable real time cpu sleeping, and optionally enable\n" \
4647 " record-and-replay mode\n", QEMU_ARCH_ALL)
4648 SRST
4649 ``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]``
4650 Enable virtual instruction counter. The virtual cpu will execute one
4651 instruction every 2^N ns of virtual time. If ``auto`` is specified
4652 then the virtual cpu speed will be automatically adjusted to keep
4653 virtual time within a few seconds of real time.
4655 Note that while this option can give deterministic behavior, it does
4656 not provide cycle accurate emulation. Modern CPUs contain
4657 superscalar out of order cores with complex cache hierarchies. The
4658 number of instructions executed often has little or no correlation
4659 with actual performance.
4661 When the virtual cpu is sleeping, the virtual time will advance at
4662 default speed unless ``sleep=on`` is specified. With
4663 ``sleep=on``, the virtual time will jump to the next timer
4664 deadline instantly whenever the virtual cpu goes to sleep mode and
4665 will not advance if no timer is enabled. This behavior gives
4666 deterministic execution times from the guest point of view.
4667 The default if icount is enabled is ``sleep=off``.
4668 ``sleep=on`` cannot be used together with either ``shift=auto``
4669 or ``align=on``.
4671 ``align=on`` will activate the delay algorithm which will try to
4672 synchronise the host clock and the virtual clock. The goal is to
4673 have a guest running at the real frequency imposed by the shift
4674 option. Whenever the guest clock is behind the host clock and if
4675 ``align=on`` is specified then we print a message to the user to
4676 inform about the delay. Currently this option does not work when
4677 ``shift`` is ``auto``. Note: The sync algorithm will work for those
4678 shift values for which the guest clock runs ahead of the host clock.
4679 Typically this happens when the shift value is high (how high
4680 depends on the host machine). The default if icount is enabled
4681 is ``align=off``.
4683 When the ``rr`` option is specified deterministic record/replay is
4684 enabled. The ``rrfile=`` option must also be provided to
4685 specify the path to the replay log. In record mode data is written
4686 to this file, and in replay mode it is read back.
4687 If the ``rrsnapshot`` option is given then it specifies a VM snapshot
4688 name. In record mode, a new VM snapshot with the given name is created
4689 at the start of execution recording. In replay mode this option
4690 specifies the snapshot name used to load the initial VM state.
4691 ERST
4693 DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
4694 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
4695 " action when watchdog fires [default=reset]\n",
4696 QEMU_ARCH_ALL)
4697 SRST
4698 ``-watchdog-action action``
4699 The action controls what QEMU will do when the watchdog timer
4700 expires. The default is ``reset`` (forcefully reset the guest).
4701 Other possible actions are: ``shutdown`` (attempt to gracefully
4702 shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
4703 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
4704 guest), ``debug`` (print a debug message and continue), or ``none``
4705 (do nothing).
4707 Note that the ``shutdown`` action requires that the guest responds
4708 to ACPI signals, which it may not be able to do in the sort of
4709 situations where the watchdog would have expired, and thus
4710 ``-watchdog-action shutdown`` is not recommended for production use.
4712 Examples:
4714 ``-device i6300esb -watchdog-action pause``
4716 ERST
4718 DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
4719 "-echr chr set terminal escape character instead of ctrl-a\n",
4720 QEMU_ARCH_ALL)
4721 SRST
4722 ``-echr numeric_ascii_value``
4723 Change the escape character used for switching to the monitor when
4724 using monitor and serial sharing. The default is ``0x01`` when using
4725 the ``-nographic`` option. ``0x01`` is equal to pressing
4726 ``Control-a``. You can select a different character from the ascii
4727 control keys where 1 through 26 map to Control-a through Control-z.
4728 For instance you could use the either of the following to change the
4729 escape character to Control-t.
4731 ``-echr 0x14``; \ ``-echr 20``
4733 ERST
4735 DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
4736 "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \
4737 "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \
4738 "-incoming unix:socketpath\n" \
4739 " prepare for incoming migration, listen on\n" \
4740 " specified protocol and socket address\n" \
4741 "-incoming fd:fd\n" \
4742 "-incoming file:filename[,offset=offset]\n" \
4743 "-incoming exec:cmdline\n" \
4744 " accept incoming migration on given file descriptor\n" \
4745 " or from given external command\n" \
4746 "-incoming defer\n" \
4747 " wait for the URI to be specified via migrate_incoming\n",
4748 QEMU_ARCH_ALL)
4749 SRST
4750 ``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]``
4752 ``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]``
4753 Prepare for incoming migration, listen on a given tcp port.
4755 ``-incoming unix:socketpath``
4756 Prepare for incoming migration, listen on a given unix socket.
4758 ``-incoming fd:fd``
4759 Accept incoming migration from a given file descriptor.
4761 ``-incoming file:filename[,offset=offset]``
4762 Accept incoming migration from a given file starting at offset.
4763 offset allows the common size suffixes, or a 0x prefix, but not both.
4765 ``-incoming exec:cmdline``
4766 Accept incoming migration as an output from specified external
4767 command.
4769 ``-incoming defer``
4770 Wait for the URI to be specified via migrate\_incoming. The monitor
4771 can be used to change settings (such as migration parameters) prior
4772 to issuing the migrate\_incoming to allow the migration to begin.
4773 ERST
4775 DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
4776 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL)
4777 SRST
4778 ``-only-migratable``
4779 Only allow migratable devices. Devices will not be allowed to enter
4780 an unmigratable state.
4781 ERST
4783 DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
4784 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL)
4785 SRST
4786 ``-nodefaults``
4787 Don't create default devices. Normally, QEMU sets the default
4788 devices like serial port, parallel port, virtual console, monitor
4789 device, VGA adapter, floppy and CD-ROM drive and others. The
4790 ``-nodefaults`` option will disable all those default devices.
4791 ERST
4793 #ifndef _WIN32
4794 DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
4795 "-runas user change to user id user just before starting the VM\n" \
4796 " user can be numeric uid:gid instead\n",
4797 QEMU_ARCH_ALL)
4798 #endif
4799 SRST
4800 ``-runas user``
4801 Immediately before starting guest execution, drop root privileges,
4802 switching to the specified user.
4803 ERST
4805 DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
4806 "-prom-env variable=value\n"
4807 " set OpenBIOS nvram variables\n",
4808 QEMU_ARCH_PPC | QEMU_ARCH_SPARC)
4809 SRST
4810 ``-prom-env variable=value``
4811 Set OpenBIOS nvram variable to given value (PPC, SPARC only).
4815 qemu-system-sparc -prom-env 'auto-boot?=false' \
4816 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
4820 qemu-system-ppc -prom-env 'auto-boot?=false' \
4821 -prom-env 'boot-device=hd:2,\yaboot' \
4822 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
4823 ERST
4824 DEF("semihosting", 0, QEMU_OPTION_semihosting,
4825 "-semihosting semihosting mode\n",
4826 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA |
4827 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV)
4828 SRST
4829 ``-semihosting``
4830 Enable :ref:`Semihosting` mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only).
4832 .. warning::
4833 Note that this allows guest direct access to the host filesystem, so
4834 should only be used with a trusted guest OS.
4836 See the -semihosting-config option documentation for further
4837 information about the facilities this enables.
4838 ERST
4839 DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
4840 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,userspace=on|off][,arg=str[,...]]\n" \
4841 " semihosting configuration\n",
4842 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA |
4843 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV)
4844 SRST
4845 ``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,userspace=on|off][,arg=str[,...]]``
4846 Enable and configure :ref:`Semihosting` (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V
4847 only).
4849 .. warning::
4850 Note that this allows guest direct access to the host filesystem, so
4851 should only be used with a trusted guest OS.
4853 ``target=native|gdb|auto``
4854 Defines where the semihosting calls will be addressed, to QEMU
4855 (``native``) or to GDB (``gdb``). The default is ``auto``, which
4856 means ``gdb`` during debug sessions and ``native`` otherwise.
4858 ``chardev=str1``
4859 Send the output to a chardev backend output for native or auto
4860 output when not in gdb
4862 ``userspace=on|off``
4863 Allows code running in guest userspace to access the semihosting
4864 interface. The default is that only privileged guest code can
4865 make semihosting calls. Note that setting ``userspace=on`` should
4866 only be used if all guest code is trusted (for example, in
4867 bare-metal test case code).
4869 ``arg=str1,arg=str2,...``
4870 Allows the user to pass input arguments, and can be used
4871 multiple times to build up a list. The old-style
4872 ``-kernel``/``-append`` method of passing a command line is
4873 still supported for backward compatibility. If both the
4874 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are
4875 specified, the former is passed to semihosting as it always
4876 takes precedence.
4877 ERST
4878 DEF("old-param", 0, QEMU_OPTION_old_param,
4879 "-old-param old param mode\n", QEMU_ARCH_ARM)
4880 SRST
4881 ``-old-param``
4882 Old param mode (ARM only).
4883 ERST
4885 DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
4886 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4887 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4888 " Enable seccomp mode 2 system call filter (default 'off').\n" \
4889 " use 'obsolete' to allow obsolete system calls that are provided\n" \
4890 " by the kernel, but typically no longer used by modern\n" \
4891 " C library implementations.\n" \
4892 " use 'elevateprivileges' to allow or deny the QEMU process ability\n" \
4893 " to elevate privileges using set*uid|gid system calls.\n" \
4894 " The value 'children' will deny set*uid|gid system calls for\n" \
4895 " main QEMU process but will allow forks and execves to run unprivileged\n" \
4896 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4897 " blocking *fork and execve\n" \
4898 " use 'resourcecontrol' to disable process affinity and schedular priority\n",
4899 QEMU_ARCH_ALL)
4900 SRST
4901 ``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]``
4902 Enable Seccomp mode 2 system call filter. 'on' will enable syscall
4903 filtering and 'off' will disable it. The default is 'off'.
4905 ``obsolete=string``
4906 Enable Obsolete system calls
4908 ``elevateprivileges=string``
4909 Disable set\*uid\|gid system calls
4911 ``spawn=string``
4912 Disable \*fork and execve
4914 ``resourcecontrol=string``
4915 Disable process affinity and schedular priority
4916 ERST
4918 DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
4919 "-readconfig <file>\n"
4920 " read config file\n", QEMU_ARCH_ALL)
4921 SRST
4922 ``-readconfig file``
4923 Read device configuration from file. This approach is useful when
4924 you want to spawn QEMU process with many command line options but
4925 you don't want to exceed the command line character limit.
4926 ERST
4928 DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4929 "-no-user-config\n"
4930 " do not load default user-provided config files at startup\n",
4931 QEMU_ARCH_ALL)
4932 SRST
4933 ``-no-user-config``
4934 The ``-no-user-config`` option makes QEMU not load any of the
4935 user-provided config files on sysconfdir.
4936 ERST
4938 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4939 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4940 " specify tracing options\n",
4941 QEMU_ARCH_ALL)
4942 SRST
4943 ``-trace [[enable=]pattern][,events=file][,file=file]``
4944 .. include:: ../qemu-option-trace.rst.inc
4946 ERST
4947 DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4948 "-plugin [file=]<file>[,<argname>=<argvalue>]\n"
4949 " load a plugin\n",
4950 QEMU_ARCH_ALL)
4951 SRST
4952 ``-plugin file=file[,argname=argvalue]``
4953 Load a plugin.
4955 ``file=file``
4956 Load the given plugin from a shared library file.
4958 ``argname=argvalue``
4959 Argument passed to the plugin. (Can be given multiple times.)
4960 ERST
4962 HXCOMM Internal use
4963 DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4964 DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4966 #ifdef CONFIG_POSIX
4967 DEF("run-with", HAS_ARG, QEMU_OPTION_run_with,
4968 "-run-with [async-teardown=on|off][,chroot=dir]\n"
4969 " Set miscellaneous QEMU process lifecycle options:\n"
4970 " async-teardown=on enables asynchronous teardown (Linux only)\n"
4971 " chroot=dir chroot to dir just before starting the VM\n",
4972 QEMU_ARCH_ALL)
4973 SRST
4974 ``-run-with [async-teardown=on|off][,chroot=dir]``
4975 Set QEMU process lifecycle options.
4977 ``async-teardown=on`` enables asynchronous teardown. A new process called
4978 "cleanup/<QEMU_PID>" will be created at startup sharing the address
4979 space with the main QEMU process, using clone. It will wait for the
4980 main QEMU process to terminate completely, and then exit. This allows
4981 QEMU to terminate very quickly even if the guest was huge, leaving the
4982 teardown of the address space to the cleanup process. Since the cleanup
4983 process shares the same cgroups as the main QEMU process, accounting is
4984 performed correctly. This only works if the cleanup process is not
4985 forcefully killed with SIGKILL before the main QEMU process has
4986 terminated completely.
4988 ``chroot=dir`` can be used for doing a chroot to the specified directory
4989 immediately before starting the guest execution. This is especially useful
4990 in combination with -runas.
4991 ERST
4992 #endif
4994 DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4995 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
4996 " control error message format\n"
4997 " timestamp=on enables timestamps (default: off)\n"
4998 " guest-name=on enables guest name prefix but only if\n"
4999 " -name guest option is set (default: off)\n",
5000 QEMU_ARCH_ALL)
5001 SRST
5002 ``-msg [timestamp[=on|off]][,guest-name[=on|off]]``
5003 Control error message format.
5005 ``timestamp=on|off``
5006 Prefix messages with a timestamp. Default is off.
5008 ``guest-name=on|off``
5009 Prefix messages with guest name but only if -name guest option is set
5010 otherwise the option is ignored. Default is off.
5011 ERST
5013 DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
5014 "-dump-vmstate <file>\n"
5015 " Output vmstate information in JSON format to file.\n"
5016 " Use the scripts/vmstate-static-checker.py file to\n"
5017 " check for possible regressions in migration code\n"
5018 " by comparing two such vmstate dumps.\n",
5019 QEMU_ARCH_ALL)
5020 SRST
5021 ``-dump-vmstate file``
5022 Dump json-encoded vmstate information for current machine type to
5023 file in file
5024 ERST
5026 DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
5027 "-enable-sync-profile\n"
5028 " enable synchronization profiling\n",
5029 QEMU_ARCH_ALL)
5030 SRST
5031 ``-enable-sync-profile``
5032 Enable synchronization profiling.
5033 ERST
5035 #if defined(CONFIG_TCG) && defined(CONFIG_LINUX)
5036 DEF("perfmap", 0, QEMU_OPTION_perfmap,
5037 "-perfmap generate a /tmp/perf-${pid}.map file for perf\n",
5038 QEMU_ARCH_ALL)
5039 SRST
5040 ``-perfmap``
5041 Generate a map file for Linux perf tools that will allow basic profiling
5042 information to be broken down into basic blocks.
5043 ERST
5045 DEF("jitdump", 0, QEMU_OPTION_jitdump,
5046 "-jitdump generate a jit-${pid}.dump file for perf\n",
5047 QEMU_ARCH_ALL)
5048 SRST
5049 ``-jitdump``
5050 Generate a dump file for Linux perf tools that maps basic blocks to symbol
5051 names, line numbers and JITted code.
5052 ERST
5053 #endif
5055 DEFHEADING()
5057 DEFHEADING(Generic object creation:)
5059 DEF("object", HAS_ARG, QEMU_OPTION_object,
5060 "-object TYPENAME[,PROP1=VALUE1,...]\n"
5061 " create a new object of type TYPENAME setting properties\n"
5062 " in the order they are specified. Note that the 'id'\n"
5063 " property must be set. These objects are placed in the\n"
5064 " '/objects' path.\n",
5065 QEMU_ARCH_ALL)
5066 SRST
5067 ``-object typename[,prop1=value1,...]``
5068 Create a new object of type typename setting properties in the order
5069 they are specified. Note that the 'id' property must be set. These
5070 objects are placed in the '/objects' path.
5072 ``-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``
5073 Creates a memory file backend object, which can be used to back
5074 the guest RAM with huge pages.
5076 The ``id`` parameter is a unique ID that will be used to
5077 reference this memory region in other parameters, e.g. ``-numa``,
5078 ``-device nvdimm``, etc.
5080 The ``size`` option provides the size of the memory region, and
5081 accepts common suffixes, e.g. ``500M``.
5083 The ``mem-path`` provides the path to either a shared memory or
5084 huge page filesystem mount.
5086 The ``share`` boolean option determines whether the memory
5087 region is marked as private to QEMU, or shared. The latter
5088 allows a co-operating external process to access the QEMU memory
5089 region.
5091 The ``share`` is also required for pvrdma devices due to
5092 limitations in the RDMA API provided by Linux.
5094 Setting share=on might affect the ability to configure NUMA
5095 bindings for the memory backend under some circumstances, see
5096 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
5097 source tree for additional details.
5099 Setting the ``discard-data`` boolean option to on indicates that
5100 file contents can be destroyed when QEMU exits, to avoid
5101 unnecessarily flushing data to the backing file. Note that
5102 ``discard-data`` is only an optimization, and QEMU might not
5103 discard file contents if it aborts unexpectedly or is terminated
5104 using SIGKILL.
5106 The ``merge`` boolean option enables memory merge, also known as
5107 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
5108 the pages for memory deduplication.
5110 Setting the ``dump`` boolean option to off excludes the memory
5111 from core dumps. This feature is also known as MADV\_DONTDUMP.
5113 The ``prealloc`` boolean option enables memory preallocation.
5115 The ``host-nodes`` option binds the memory range to a list of
5116 NUMA host nodes.
5118 The ``policy`` option sets the NUMA policy to one of the
5119 following values:
5121 ``default``
5122 default host policy
5124 ``preferred``
5125 prefer the given host node list for allocation
5127 ``bind``
5128 restrict memory allocation to the given host node list
5130 ``interleave``
5131 interleave memory allocations across the given host node
5132 list
5134 The ``align`` option specifies the base address alignment when
5135 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
5136 ``2M``. Some backend store specified by ``mem-path`` requires an
5137 alignment different than the default one used by QEMU, eg the
5138 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
5139 such cases, users can specify the required alignment via this
5140 option.
5142 The ``offset`` option specifies the offset into the target file
5143 that the region starts at. You can use this parameter to back
5144 multiple regions with a single file.
5146 The ``pmem`` option specifies whether the backing file specified
5147 by ``mem-path`` is in host persistent memory that can be
5148 accessed using the SNIA NVM programming model (e.g. Intel
5149 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary
5150 operations to guarantee the persistence of its own writes to
5151 ``mem-path`` (e.g. in vNVDIMM label emulation and live
5152 migration). Also, we will map the backend-file with MAP\_SYNC
5153 flag, which ensures the file metadata is in sync for
5154 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
5155 requires support from both the host kernel (since Linux kernel
5156 4.15) and the filesystem of ``mem-path`` mounted with DAX
5157 option.
5159 The ``readonly`` option specifies whether the backing file is opened
5160 read-only or read-write (default).
5162 The ``rom`` option specifies whether to create Read Only Memory
5163 (ROM) that cannot be modified by the VM. Any write attempts to such
5164 ROM will be denied. Most use cases want proper RAM instead of ROM.
5165 However, selected use cases, like R/O NVDIMMs, can benefit from
5166 ROM. If set to ``on``, create ROM; if set to ``off``, create
5167 writable RAM; if set to ``auto`` (default), the value of the
5168 ``readonly`` option is used. This option is primarily helpful when
5169 we want to have writable RAM in configurations that would
5170 traditionally create ROM before the ``rom`` option was introduced:
5171 VM templating, where we want to open a file readonly
5172 (``readonly=on``) and mark the memory to be private for QEMU
5173 (``share=off``). For this use case, we need writable RAM instead
5174 of ROM, and want to also set ``rom=off``.
5176 ``-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``
5177 Creates a memory backend object, which can be used to back the
5178 guest RAM. Memory backend objects offer more control than the
5179 ``-m`` option that is traditionally used to define guest RAM.
5180 Please refer to ``memory-backend-file`` for a description of the
5181 options.
5183 ``-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``
5184 Creates an anonymous memory file backend object, which allows
5185 QEMU to share the memory with an external process (e.g. when
5186 using vhost-user). The memory is allocated with memfd and
5187 optional sealing. (Linux only)
5189 The ``seal`` option creates a sealed-file, that will block
5190 further resizing the memory ('on' by default).
5192 The ``hugetlb`` option specify the file to be created resides in
5193 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
5194 with the ``hugetlb`` option, the ``hugetlbsize`` option specify
5195 the hugetlb page size on systems that support multiple hugetlb
5196 page sizes (it must be a power of 2 value supported by the
5197 system).
5199 In some versions of Linux, the ``hugetlb`` option is
5200 incompatible with the ``seal`` option (requires at least Linux
5201 4.16).
5203 Please refer to ``memory-backend-file`` for a description of the
5204 other options.
5206 The ``share`` boolean option is on by default with memfd.
5208 ``-object iommufd,id=id[,fd=fd]``
5209 Creates an iommufd backend which allows control of DMA mapping
5210 through the ``/dev/iommu`` device.
5212 The ``id`` parameter is a unique ID which frontends (such as
5213 vfio-pci of vdpa) will use to connect with the iommufd backend.
5215 The ``fd`` parameter is an optional pre-opened file descriptor
5216 resulting from ``/dev/iommu`` opening. Usually the iommufd is shared
5217 across all subsystems, bringing the benefit of centralized
5218 reference counting.
5220 ``-object rng-builtin,id=id``
5221 Creates a random number generator backend which obtains entropy
5222 from QEMU builtin functions. The ``id`` parameter is a unique ID
5223 that will be used to reference this entropy backend from the
5224 ``virtio-rng`` device. By default, the ``virtio-rng`` device
5225 uses this RNG backend.
5227 ``-object rng-random,id=id,filename=/dev/random``
5228 Creates a random number generator backend which obtains entropy
5229 from a device on the host. The ``id`` parameter is a unique ID
5230 that will be used to reference this entropy backend from the
5231 ``virtio-rng`` device. The ``filename`` parameter specifies
5232 which file to obtain entropy from and if omitted defaults to
5233 ``/dev/urandom``.
5235 ``-object rng-egd,id=id,chardev=chardevid``
5236 Creates a random number generator backend which obtains entropy
5237 from an external daemon running on the host. The ``id``
5238 parameter is a unique ID that will be used to reference this
5239 entropy backend from the ``virtio-rng`` device. The ``chardev``
5240 parameter is the unique ID of a character device backend that
5241 provides the connection to the RNG daemon.
5243 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
5244 Creates a TLS anonymous credentials object, which can be used to
5245 provide TLS support on network backends. The ``id`` parameter is
5246 a unique ID which network backends will use to access the
5247 credentials. The ``endpoint`` is either ``server`` or ``client``
5248 depending on whether the QEMU network backend that uses the
5249 credentials will be acting as a client or as a server. If
5250 ``verify-peer`` is enabled (the default) then once the handshake
5251 is completed, the peer credentials will be verified, though this
5252 is a no-op for anonymous credentials.
5254 The dir parameter tells QEMU where to find the credential files.
5255 For server endpoints, this directory may contain a file
5256 dh-params.pem providing diffie-hellman parameters to use for the
5257 TLS server. If the file is missing, QEMU will generate a set of
5258 DH parameters at startup. This is a computationally expensive
5259 operation that consumes random pool entropy, so it is
5260 recommended that a persistent set of parameters be generated
5261 upfront and saved.
5263 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
5264 Creates a TLS Pre-Shared Keys (PSK) credentials object, which
5265 can be used to provide TLS support on network backends. The
5266 ``id`` parameter is a unique ID which network backends will use
5267 to access the credentials. The ``endpoint`` is either ``server``
5268 or ``client`` depending on whether the QEMU network backend that
5269 uses the credentials will be acting as a client or as a server.
5270 For clients only, ``username`` is the username which will be
5271 sent to the server. If omitted it defaults to "qemu".
5273 The dir parameter tells QEMU where to find the keys file. It is
5274 called "dir/keys.psk" and contains "username:key" pairs. This
5275 file can most easily be created using the GnuTLS ``psktool``
5276 program.
5278 For server endpoints, dir may also contain a file dh-params.pem
5279 providing diffie-hellman parameters to use for the TLS server.
5280 If the file is missing, QEMU will generate a set of DH
5281 parameters at startup. This is a computationally expensive
5282 operation that consumes random pool entropy, so it is
5283 recommended that a persistent set of parameters be generated up
5284 front and saved.
5286 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
5287 Creates a TLS anonymous credentials object, which can be used to
5288 provide TLS support on network backends. The ``id`` parameter is
5289 a unique ID which network backends will use to access the
5290 credentials. The ``endpoint`` is either ``server`` or ``client``
5291 depending on whether the QEMU network backend that uses the
5292 credentials will be acting as a client or as a server. If
5293 ``verify-peer`` is enabled (the default) then once the handshake
5294 is completed, the peer credentials will be verified. With x509
5295 certificates, this implies that the clients must be provided
5296 with valid client certificates too.
5298 The dir parameter tells QEMU where to find the credential files.
5299 For server endpoints, this directory may contain a file
5300 dh-params.pem providing diffie-hellman parameters to use for the
5301 TLS server. If the file is missing, QEMU will generate a set of
5302 DH parameters at startup. This is a computationally expensive
5303 operation that consumes random pool entropy, so it is
5304 recommended that a persistent set of parameters be generated
5305 upfront and saved.
5307 For x509 certificate credentials the directory will contain
5308 further files providing the x509 certificates. The certificates
5309 must be stored in PEM format, in filenames ca-cert.pem,
5310 ca-crl.pem (optional), server-cert.pem (only servers),
5311 server-key.pem (only servers), client-cert.pem (only clients),
5312 and client-key.pem (only clients).
5314 For the server-key.pem and client-key.pem files which contain
5315 sensitive private keys, it is possible to use an encrypted
5316 version by providing the passwordid parameter. This provides the
5317 ID of a previously created ``secret`` object containing the
5318 password for decryption.
5320 The priority parameter allows to override the global default
5321 priority used by gnutls. This can be useful if the system
5322 administrator needs to use a weaker set of crypto priorities for
5323 QEMU without potentially forcing the weakness onto all
5324 applications. Or conversely if one wants wants a stronger
5325 default for QEMU than for all other applications, they can do
5326 this through this parameter. Its format is a gnutls priority
5327 string as described at
5328 https://gnutls.org/manual/html_node/Priority-Strings.html.
5330 ``-object tls-cipher-suites,id=id,priority=priority``
5331 Creates a TLS cipher suites object, which can be used to control
5332 the TLS cipher/protocol algorithms that applications are permitted
5333 to use.
5335 The ``id`` parameter is a unique ID which frontends will use to
5336 access the ordered list of permitted TLS cipher suites from the
5337 host.
5339 The ``priority`` parameter allows to override the global default
5340 priority used by gnutls. This can be useful if the system
5341 administrator needs to use a weaker set of crypto priorities for
5342 QEMU without potentially forcing the weakness onto all
5343 applications. Or conversely if one wants wants a stronger
5344 default for QEMU than for all other applications, they can do
5345 this through this parameter. Its format is a gnutls priority
5346 string as described at
5347 https://gnutls.org/manual/html_node/Priority-Strings.html.
5349 An example of use of this object is to control UEFI HTTPS Boot.
5350 The tls-cipher-suites object exposes the ordered list of permitted
5351 TLS cipher suites from the host side to the guest firmware, via
5352 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER
5353 objects. The firmware uses the IANA_TLS_CIPHER array for configuring
5354 guest-side TLS.
5356 In the following example, the priority at which the host-side policy
5357 is retrieved is given by the ``priority`` property.
5358 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to
5359 refer to /etc/crypto-policies/back-ends/gnutls.config.
5361 .. parsed-literal::
5363 # |qemu_system| \\
5364 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\
5365 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0
5367 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
5368 Interval t can't be 0, this filter batches the packet delivery:
5369 all packets arriving in a given interval on netdev netdevid are
5370 delayed until the end of the interval. Interval is in
5371 microseconds. ``status`` is optional that indicate whether the
5372 netfilter is on (enabled) or off (disabled), the default status
5373 for netfilter will be 'on'.
5375 queue all\|rx\|tx is an option that can be applied to any
5376 netfilter.
5378 ``all``: the filter is attached both to the receive and the
5379 transmit queue of the netdev (default).
5381 ``rx``: the filter is attached to the receive queue of the
5382 netdev, where it will receive packets sent to the netdev.
5384 ``tx``: the filter is attached to the transmit queue of the
5385 netdev, where it will receive packets sent by the netdev.
5387 position head\|tail\|id=<id> is an option to specify where the
5388 filter should be inserted in the filter list. It can be applied
5389 to any netfilter.
5391 ``head``: the filter is inserted at the head of the filter list,
5392 before any existing filters.
5394 ``tail``: the filter is inserted at the tail of the filter list,
5395 behind any existing filters (default).
5397 ``id=<id>``: the filter is inserted before or behind the filter
5398 specified by <id>, see the insert option below.
5400 insert behind\|before is an option to specify where to insert
5401 the new filter relative to the one specified with
5402 position=id=<id>. It can be applied to any netfilter.
5404 ``before``: insert before the specified filter.
5406 ``behind``: insert behind the specified filter (default).
5408 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
5409 filter-mirror on netdev netdevid,mirror net packet to
5410 chardevchardevid, if it has the vnet\_hdr\_support flag,
5411 filter-mirror will mirror packet with vnet\_hdr\_len.
5413 ``-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]``
5414 filter-redirector on netdev netdevid,redirect filter's net
5415 packet to chardev chardevid,and redirect indev's packet to
5416 filter.if it has the vnet\_hdr\_support flag, filter-redirector
5417 will redirect packet with vnet\_hdr\_len. Create a
5418 filter-redirector we need to differ outdev id from indev id, id
5419 can not be the same. we can just use indev or outdev, but at
5420 least one of indev or outdev need to be specified.
5422 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
5423 Filter-rewriter is a part of COLO project.It will rewrite tcp
5424 packet to secondary from primary to keep secondary tcp
5425 connection,and rewrite tcp packet to primary from secondary make
5426 tcp packet can be handled by client.if it has the
5427 vnet\_hdr\_support flag, we can parse packet with vnet header.
5429 usage: colo secondary: -object
5430 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object
5431 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object
5432 filter-rewriter,id=rew0,netdev=hn0,queue=all
5434 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]``
5435 Dump the network traffic on netdev dev to the file specified by
5436 filename. At most len bytes (64k by default) per packet are
5437 stored. The file format is libpcap, so it can be analyzed with
5438 tools such as tcpdump or Wireshark.
5440 ``-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}]``
5441 Colo-compare gets packet from primary\_in chardevid and
5442 secondary\_in, then compare whether the payload of primary packet
5443 and secondary packet are the same. If same, it will output
5444 primary packet to out\_dev, else it will notify COLO-framework to do
5445 checkpoint and send primary packet to out\_dev. In order to
5446 improve efficiency, we need to put the task of comparison in
5447 another iothread. If it has the vnet\_hdr\_support flag,
5448 colo compare will send/recv packet with vnet\_hdr\_len.
5449 The compare\_timeout=@var{ms} determines the maximum time of the
5450 colo-compare hold the packet. The expired\_scan\_cycle=@var{ms}
5451 is to set the period of scanning expired primary node network packets.
5452 The max\_queue\_size=@var{size} is to set the max compare queue
5453 size depend on user environment.
5454 If user want to use Xen COLO, need to add the notify\_dev to
5455 notify Xen colo-frame to do checkpoint.
5457 COLO-compare must be used with the help of filter-mirror,
5458 filter-redirector and filter-rewriter.
5462 KVM COLO
5464 primary:
5465 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
5466 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
5467 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off
5468 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off
5469 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off
5470 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
5471 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off
5472 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
5473 -object iothread,id=iothread1
5474 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
5475 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
5476 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
5477 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
5479 secondary:
5480 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
5481 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5482 -chardev socket,id=red0,host=3.3.3.3,port=9003
5483 -chardev socket,id=red1,host=3.3.3.3,port=9004
5484 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5485 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5488 Xen COLO
5490 primary:
5491 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
5492 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
5493 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off
5494 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off
5495 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off
5496 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
5497 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off
5498 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
5499 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server=on,wait=off
5500 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
5501 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
5502 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
5503 -object iothread,id=iothread1
5504 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1
5506 secondary:
5507 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
5508 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
5509 -chardev socket,id=red0,host=3.3.3.3,port=9003
5510 -chardev socket,id=red1,host=3.3.3.3,port=9004
5511 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
5512 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
5514 If you want to know the detail of above command line, you can
5515 read the colo-compare git log.
5517 ``-object cryptodev-backend-builtin,id=id[,queues=queues]``
5518 Creates a cryptodev backend which executes crypto operations from
5519 the QEMU cipher APIs. The id parameter is a unique ID that will
5520 be used to reference this cryptodev backend from the
5521 ``virtio-crypto`` device. The queues parameter is optional,
5522 which specify the queue number of cryptodev backend, the default
5523 of queues is 1.
5525 .. parsed-literal::
5527 # |qemu_system| \\
5528 [...] \\
5529 -object cryptodev-backend-builtin,id=cryptodev0 \\
5530 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5531 [...]
5533 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]``
5534 Creates a vhost-user cryptodev backend, backed by a chardev
5535 chardevid. The id parameter is a unique ID that will be used to
5536 reference this cryptodev backend from the ``virtio-crypto``
5537 device. The chardev should be a unix domain socket backed one.
5538 The vhost-user uses a specifically defined protocol to pass
5539 vhost ioctl replacement messages to an application on the other
5540 end of the socket. The queues parameter is optional, which
5541 specify the queue number of cryptodev backend for multiqueue
5542 vhost-user, the default of queues is 1.
5544 .. parsed-literal::
5546 # |qemu_system| \\
5547 [...] \\
5548 -chardev socket,id=chardev0,path=/path/to/socket \\
5549 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\
5550 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
5551 [...]
5553 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]``
5555 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]``
5556 Defines a secret to store a password, encryption key, or some
5557 other sensitive data. The sensitive data can either be passed
5558 directly via the data parameter, or indirectly via the file
5559 parameter. Using the data parameter is insecure unless the
5560 sensitive data is encrypted.
5562 The sensitive data can be provided in raw format (the default),
5563 or base64. When encoded as JSON, the raw format only supports
5564 valid UTF-8 characters, so base64 is recommended for sending
5565 binary data. QEMU will convert from which ever format is
5566 provided to the format it needs internally. eg, an RBD password
5567 can be provided in raw format, even though it will be base64
5568 encoded when passed onto the RBD sever.
5570 For added protection, it is possible to encrypt the data
5571 associated with a secret using the AES-256-CBC cipher. Use of
5572 encryption is indicated by providing the keyid and iv
5573 parameters. The keyid parameter provides the ID of a previously
5574 defined secret that contains the AES-256 decryption key. This
5575 key should be 32-bytes long and be base64 encoded. The iv
5576 parameter provides the random initialization vector used for
5577 encryption of this particular secret and should be a base64
5578 encrypted string of the 16-byte IV.
5580 The simplest (insecure) usage is to provide the secret inline
5582 .. parsed-literal::
5584 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw
5586 The simplest secure usage is to provide the secret via a file
5588 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object
5589 secret,id=sec0,file=mypasswd.txt,format=raw
5591 For greater security, AES-256-CBC should be used. To illustrate
5592 usage, consider the openssl command line tool which can encrypt
5593 the data. Note that when encrypting, the plaintext must be
5594 padded to the cipher block size (32 bytes) using the standard
5595 PKCS#5/6 compatible padding algorithm.
5597 First a master key needs to be created in base64 encoding:
5601 # openssl rand -base64 32 > key.b64
5602 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"')
5604 Each secret to be encrypted needs to have a random
5605 initialization vector generated. These do not need to be kept
5606 secret
5610 # openssl rand -base64 16 > iv.b64
5611 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"')
5613 The secret to be defined can now be encrypted, in this case
5614 we're telling openssl to base64 encode the result, but it could
5615 be left as raw bytes if desired.
5619 # SECRET=$(printf "letmein" |
5620 openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
5622 When launching QEMU, create a master secret pointing to
5623 ``key.b64`` and specify that to be used to decrypt the user
5624 password. Pass the contents of ``iv.b64`` to the second secret
5626 .. parsed-literal::
5628 # |qemu_system| \\
5629 -object secret,id=secmaster0,format=base64,file=key.b64 \\
5630 -object secret,id=sec0,keyid=secmaster0,format=base64,\\
5631 data=$SECRET,iv=$(<iv.b64)
5633 ``-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]``
5634 Create a Secure Encrypted Virtualization (SEV) guest object,
5635 which can be used to provide the guest memory encryption support
5636 on AMD processors.
5638 When memory encryption is enabled, one of the physical address
5639 bit (aka the C-bit) is utilized to mark if a memory page is
5640 protected. The ``cbitpos`` is used to provide the C-bit
5641 position. The C-bit position is Host family dependent hence user
5642 must provide this value. On EPYC, the value should be 47.
5644 When memory encryption is enabled, we loose certain bits in
5645 physical address space. The ``reduced-phys-bits`` is used to
5646 provide the number of bits we loose in physical address space.
5647 Similar to C-bit, the value is Host family dependent. On EPYC,
5648 a guest will lose a maximum of 1 bit, so the value should be 1.
5650 The ``sev-device`` provides the device file to use for
5651 communicating with the SEV firmware running inside AMD Secure
5652 Processor. The default device is '/dev/sev'. If hardware
5653 supports memory encryption then /dev/sev devices are created by
5654 CCP driver.
5656 The ``policy`` provides the guest policy to be enforced by the
5657 SEV firmware and restrict what configuration and operational
5658 commands can be performed on this guest by the hypervisor. The
5659 policy should be provided by the guest owner and is bound to the
5660 guest and cannot be changed throughout the lifetime of the
5661 guest. The default is 0.
5663 If guest ``policy`` allows sharing the key with another SEV
5664 guest then ``handle`` can be use to provide handle of the guest
5665 from which to share the key.
5667 The ``dh-cert-file`` and ``session-file`` provides the guest
5668 owner's Public Diffie-Hillman key defined in SEV spec. The PDH
5669 and session parameters are used for establishing a cryptographic
5670 session with the guest owner to negotiate keys used for
5671 attestation. The file must be encoded in base64.
5673 The ``kernel-hashes`` adds the hashes of given kernel/initrd/
5674 cmdline to a designated guest firmware page for measured Linux
5675 boot with -kernel. The default is off. (Since 6.2)
5677 e.g to launch a SEV guest
5679 .. parsed-literal::
5681 # |qemu_system_x86| \\
5682 ...... \\
5683 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=1 \\
5684 -machine ...,memory-encryption=sev0 \\
5685 .....
5687 ``-object authz-simple,id=id,identity=string``
5688 Create an authorization object that will control access to
5689 network services.
5691 The ``identity`` parameter is identifies the user and its format
5692 depends on the network service that authorization object is
5693 associated with. For authorizing based on TLS x509 certificates,
5694 the identity must be the x509 distinguished name. Note that care
5695 must be taken to escape any commas in the distinguished name.
5697 An example authorization object to validate a x509 distinguished
5698 name would look like:
5700 .. parsed-literal::
5702 # |qemu_system| \\
5703 ... \\
5704 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\
5707 Note the use of quotes due to the x509 distinguished name
5708 containing whitespace, and escaping of ','.
5710 ``-object authz-listfile,id=id,filename=path,refresh=on|off``
5711 Create an authorization object that will control access to
5712 network services.
5714 The ``filename`` parameter is the fully qualified path to a file
5715 containing the access control list rules in JSON format.
5717 An example set of rules that match against SASL usernames might
5718 look like:
5723 "rules": [
5724 { "match": "fred", "policy": "allow", "format": "exact" },
5725 { "match": "bob", "policy": "allow", "format": "exact" },
5726 { "match": "danb", "policy": "deny", "format": "glob" },
5727 { "match": "dan*", "policy": "allow", "format": "exact" },
5729 "policy": "deny"
5732 When checking access the object will iterate over all the rules
5733 and the first rule to match will have its ``policy`` value
5734 returned as the result. If no rules match, then the default
5735 ``policy`` value is returned.
5737 The rules can either be an exact string match, or they can use
5738 the simple UNIX glob pattern matching to allow wildcards to be
5739 used.
5741 If ``refresh`` is set to true the file will be monitored and
5742 automatically reloaded whenever its content changes.
5744 As with the ``authz-simple`` object, the format of the identity
5745 strings being matched depends on the network service, but is
5746 usually a TLS x509 distinguished name, or a SASL username.
5748 An example authorization object to validate a SASL username
5749 would look like:
5751 .. parsed-literal::
5753 # |qemu_system| \\
5754 ... \\
5755 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\
5758 ``-object authz-pam,id=id,service=string``
5759 Create an authorization object that will control access to
5760 network services.
5762 The ``service`` parameter provides the name of a PAM service to
5763 use for authorization. It requires that a file
5764 ``/etc/pam.d/service`` exist to provide the configuration for
5765 the ``account`` subsystem.
5767 An example authorization object to validate a TLS x509
5768 distinguished name would look like:
5770 .. parsed-literal::
5772 # |qemu_system| \\
5773 ... \\
5774 -object authz-pam,id=auth0,service=qemu-vnc \\
5777 There would then be a corresponding config file for PAM at
5778 ``/etc/pam.d/qemu-vnc`` that contains:
5782 account requisite pam_listfile.so item=user sense=allow \
5783 file=/etc/qemu/vnc.allow
5785 Finally the ``/etc/qemu/vnc.allow`` file would contain the list
5786 of x509 distinguished names that are permitted access
5790 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
5792 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch``
5793 Creates a dedicated event loop thread that devices can be
5794 assigned to. This is known as an IOThread. By default device
5795 emulation happens in vCPU threads or the main event loop thread.
5796 This can become a scalability bottleneck. IOThreads allow device
5797 emulation and I/O to run on other host CPUs.
5799 The ``id`` parameter is a unique ID that will be used to
5800 reference this IOThread from ``-device ...,iothread=id``.
5801 Multiple devices can be assigned to an IOThread. Note that not
5802 all devices support an ``iothread`` parameter.
5804 The ``query-iothreads`` QMP command lists IOThreads and reports
5805 their thread IDs so that the user can configure host CPU
5806 pinning/affinity.
5808 IOThreads use an adaptive polling algorithm to reduce event loop
5809 latency. Instead of entering a blocking system call to monitor
5810 file descriptors and then pay the cost of being woken up when an
5811 event occurs, the polling algorithm spins waiting for events for
5812 a short time. The algorithm's default parameters are suitable
5813 for many cases but can be adjusted based on knowledge of the
5814 workload and/or host device latency.
5816 The ``poll-max-ns`` parameter is the maximum number of
5817 nanoseconds to busy wait for events. Polling can be disabled by
5818 setting this value to 0.
5820 The ``poll-grow`` parameter is the multiplier used to increase
5821 the polling time when the algorithm detects it is missing events
5822 due to not polling long enough.
5824 The ``poll-shrink`` parameter is the divisor used to decrease
5825 the polling time when the algorithm detects it is spending too
5826 long polling without encountering events.
5828 The ``aio-max-batch`` parameter is the maximum number of requests
5829 in a batch for the AIO engine, 0 means that the engine will use
5830 its default.
5832 The IOThread parameters can be modified at run-time using the
5833 ``qom-set`` command (where ``iothread1`` is the IOThread's
5834 ``id``):
5838 (qemu) qom-set /objects/iothread1 poll-max-ns 100000
5839 ERST
5842 HXCOMM This is the last statement. Insert new options before this line!
5844 #undef DEF
5845 #undef DEFHEADING
5846 #undef ARCHHEADING