iotests/210: Fix reference output
[qemu.git] / qemu-options.hx
blob6c34c7050f63f6629d65bf81b669c61ee9bf5c28
1 HXCOMM Use DEFHEADING() to define headings in both help text and rST.
2 HXCOMM Text between SRST and ERST is copied to the rST version and
3 HXCOMM discarded from C version.
4 HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to
5 HXCOMM construct option structures, enums and help message for specified
6 HXCOMM architectures.
7 HXCOMM HXCOMM can be used for comments, discarded from both rST and C.
9 DEFHEADING(Standard options:)
11 DEF("help", 0, QEMU_OPTION_h,
12 "-h or -help display this help and exit\n", QEMU_ARCH_ALL)
13 SRST
14 ``-h``
15 Display help and exit
16 ERST
18 DEF("version", 0, QEMU_OPTION_version,
19 "-version display version information and exit\n", QEMU_ARCH_ALL)
20 SRST
21 ``-version``
22 Display version information and exit
23 ERST
25 DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
26 "-machine [type=]name[,prop[=value][,...]]\n"
27 " selects emulated machine ('-machine help' for list)\n"
28 " property accel=accel1[:accel2[:...]] selects accelerator\n"
29 " supported accelerators are kvm, xen, hax, hvf, whpx or tcg (default: tcg)\n"
30 " vmport=on|off|auto controls emulation of vmport (default: auto)\n"
31 " dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
32 " mem-merge=on|off controls memory merge support (default: on)\n"
33 " aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
34 " dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
35 " suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
36 " nvdimm=on|off controls NVDIMM support (default=off)\n"
37 " memory-encryption=@var{} memory encryption object to use (default=none)\n"
38 " hmat=on|off controls ACPI HMAT support (default=off)\n"
39 " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n",
40 QEMU_ARCH_ALL)
41 SRST
42 ``-machine [type=]name[,prop=value[,...]]``
43 Select the emulated machine by name. Use ``-machine help`` to list
44 available machines.
46 For architectures which aim to support live migration compatibility
47 across releases, each release will introduce a new versioned machine
48 type. For example, the 2.8.0 release introduced machine types
49 "pc-i440fx-2.8" and "pc-q35-2.8" for the x86\_64/i686 architectures.
51 To allow live migration of guests from QEMU version 2.8.0, to QEMU
52 version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8"
53 and "pc-q35-2.8" machines too. To allow users live migrating VMs to
54 skip multiple intermediate releases when upgrading, new releases of
55 QEMU will support machine types from many previous versions.
57 Supported machine properties are:
59 ``accel=accels1[:accels2[:...]]``
60 This is used to enable an accelerator. Depending on the target
61 architecture, kvm, xen, hax, hvf, whpx or tcg can be available.
62 By default, tcg is used. If there is more than one accelerator
63 specified, the next one is used if the previous one fails to
64 initialize.
66 ``vmport=on|off|auto``
67 Enables emulation of VMWare IO port, for vmmouse etc. auto says
68 to select the value based on accel. For accel=xen the default is
69 off otherwise the default is on.
71 ``dump-guest-core=on|off``
72 Include guest memory in a core dump. The default is on.
74 ``mem-merge=on|off``
75 Enables or disables memory merge support. This feature, when
76 supported by the host, de-duplicates identical memory pages
77 among VMs instances (enabled by default).
79 ``aes-key-wrap=on|off``
80 Enables or disables AES key wrapping support on s390-ccw hosts.
81 This feature controls whether AES wrapping keys will be created
82 to allow execution of AES cryptographic functions. The default
83 is on.
85 ``dea-key-wrap=on|off``
86 Enables or disables DEA key wrapping support on s390-ccw hosts.
87 This feature controls whether DEA wrapping keys will be created
88 to allow execution of DEA cryptographic functions. The default
89 is on.
91 ``nvdimm=on|off``
92 Enables or disables NVDIMM support. The default is off.
94 ``memory-encryption=``
95 Memory encryption object to use. The default is none.
97 ``hmat=on|off``
98 Enables or disables ACPI Heterogeneous Memory Attribute Table
99 (HMAT) support. The default is off.
101 ``memory-backend='id'``
102 An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options.
103 Allows to use a memory backend as main RAM.
105 For example:
107 -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on
108 -machine memory-backend=pc.ram
109 -m 512M
111 Migration compatibility note:
112 a) as backend id one shall use value of 'default-ram-id', advertised by
113 machine type (available via ``query-machines`` QMP command), if migration
114 to/from old QEMU (<5.0) is expected.
115 b) for machine types 4.0 and older, user shall
116 use ``x-use-canonical-path-for-ramblock-id=off`` backend option
117 if migration to/from old QEMU (<5.0) is expected.
118 For example:
120 -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off
121 -machine memory-backend=pc.ram
122 -m 512M
123 ERST
125 HXCOMM Deprecated by -machine
126 DEF("M", HAS_ARG, QEMU_OPTION_M, "", QEMU_ARCH_ALL)
128 DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
129 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
130 SRST
131 ``-cpu model``
132 Select CPU model (``-cpu help`` for list and additional feature
133 selection)
134 ERST
136 DEF("accel", HAS_ARG, QEMU_OPTION_accel,
137 "-accel [accel=]accelerator[,prop[=value][,...]]\n"
138 " select accelerator (kvm, xen, hax, hvf, whpx or tcg; use 'help' for a list)\n"
139 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
140 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
141 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
142 " split-wx=on|off (enable TCG split w^x mapping)\n"
143 " tb-size=n (TCG translation block cache size)\n"
144 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
145 SRST
146 ``-accel name[,prop=value[,...]]``
147 This is used to enable an accelerator. Depending on the target
148 architecture, kvm, xen, hax, hvf, whpx or tcg can be available. By
149 default, tcg is used. If there is more than one accelerator
150 specified, the next one is used if the previous one fails to
151 initialize.
153 ``igd-passthru=on|off``
154 When Xen is in use, this option controls whether Intel
155 integrated graphics devices can be passed through to the guest
156 (default=off)
158 ``kernel-irqchip=on|off|split``
159 Controls KVM in-kernel irqchip support. The default is full
160 acceleration of the interrupt controllers. On x86, split irqchip
161 reduces the kernel attack surface, at a performance cost for
162 non-MSI interrupts. Disabling the in-kernel irqchip completely
163 is not recommended except for debugging purposes.
165 ``kvm-shadow-mem=size``
166 Defines the size of the KVM shadow MMU.
168 ``split-wx=on|off``
169 Controls the use of split w^x mapping for the TCG code generation
170 buffer. Some operating systems require this to be enabled, and in
171 such a case this will default on. On other operating systems, this
172 will default off, but one may enable this for testing or debugging.
174 ``tb-size=n``
175 Controls the size (in MiB) of the TCG translation block cache.
177 ``thread=single|multi``
178 Controls number of TCG threads. When the TCG is multi-threaded
179 there will be one thread per vCPU therefor taking advantage of
180 additional host cores. The default is to enable multi-threading
181 where both the back-end and front-ends support it and no
182 incompatible TCG features have been enabled (e.g.
183 icount/replay).
184 ERST
186 DEF("smp", HAS_ARG, QEMU_OPTION_smp,
187 "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n"
188 " set the number of CPUs to 'n' [default=1]\n"
189 " maxcpus= maximum number of total cpus, including\n"
190 " offline CPUs for hotplug, etc\n"
191 " cores= number of CPU cores on one socket (for PC, it's on one die)\n"
192 " threads= number of threads on one CPU core\n"
193 " dies= number of CPU dies on one socket (for PC only)\n"
194 " sockets= number of discrete sockets in the system\n",
195 QEMU_ARCH_ALL)
196 SRST
197 ``-smp [cpus=]n[,cores=cores][,threads=threads][,dies=dies][,sockets=sockets][,maxcpus=maxcpus]``
198 Simulate an SMP system with n CPUs. On the PC target, up to 255 CPUs
199 are supported. On Sparc32 target, Linux limits the number of usable
200 CPUs to 4. For the PC target, the number of cores per die, the
201 number of threads per cores, the number of dies per packages and the
202 total number of sockets can be specified. Missing values will be
203 computed. If any on the three values is given, the total number of
204 CPUs n can be omitted. maxcpus specifies the maximum number of
205 hotpluggable CPUs.
206 ERST
208 DEF("numa", HAS_ARG, QEMU_OPTION_numa,
209 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
210 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
211 "-numa dist,src=source,dst=destination,val=distance\n"
212 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
213 "-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"
214 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
215 QEMU_ARCH_ALL)
216 SRST
217 ``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
219 ``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
221 ``-numa dist,src=source,dst=destination,val=distance``
223 ``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]``
225 ``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]``
227 ``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]``
228 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA
229 distance from a source node to a destination node. Set the ACPI
230 Heterogeneous Memory Attributes for the given nodes.
232 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and
233 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a
234 contiguous range of CPU indexes (or a single VCPU if lastcpu is
235 omitted). A non-contiguous set of VCPUs can be represented by
236 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is
237 omitted on all nodes, VCPUs are automatically split between them.
239 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a
240 NUMA node:
244 -numa node,cpus=0-2,cpus=5
246 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option
247 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to
248 assign CPU objects to a node using topology layout properties of
249 CPU. The set of properties is machine specific, and depends on used
250 machine type/'\ ``smp``\ ' options. It could be queried with
251 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ '
252 property specifies node to which CPU object will be assigned, it's
253 required for node to be declared with '\ ``node``\ ' option before
254 it's used with '\ ``cpu``\ ' option.
256 For example:
260 -M pc \
261 -smp 1,sockets=2,maxcpus=2 \
262 -numa node,nodeid=0 -numa node,nodeid=1 \
263 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
265 Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported
266 for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from
267 a given memory backend device to a node. If '\ ``mem``\ ' and
268 '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them.
271 '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive.
272 Furthermore, if one node uses '\ ``memdev``\ ', all of them have to
273 use it.
275 '\ ``initiator``\ ' is an additional option that points to an
276 initiator NUMA node that has best performance (the lowest latency or
277 largest bandwidth) to this NUMA node. Note that this option can be
278 set only when the machine property 'hmat' is set to 'on'.
280 Following example creates a machine with 2 NUMA nodes, node 0 has
281 CPU. node 1 has only memory, and its initiator is node 0. Note that
282 because node 0 has CPU, by default the initiator of node 0 is itself
283 and must be itself.
287 -machine hmat=on \
288 -m 2G,slots=2,maxmem=4G \
289 -object memory-backend-ram,size=1G,id=m0 \
290 -object memory-backend-ram,size=1G,id=m1 \
291 -numa node,nodeid=0,memdev=m0 \
292 -numa node,nodeid=1,memdev=m1,initiator=0 \
293 -smp 2,sockets=2,maxcpus=2 \
294 -numa cpu,node-id=0,socket-id=0 \
295 -numa cpu,node-id=0,socket-id=1
297 source and destination are NUMA node IDs. distance is the NUMA
298 distance from source to destination. The distance from a node to
299 itself is always 10. If any pair of nodes is given a distance, then
300 all pairs must be given distances. Although, when distances are only
301 given in one direction for each pair of nodes, then the distances in
302 the opposite directions are assumed to be the same. If, however, an
303 asymmetrical pair of distances is given for even one node pair, then
304 all node pairs must be provided distance values for both directions,
305 even when they are symmetrical. When a node is unreachable from
306 another node, set the pair's distance to 255.
308 Note that the -``numa`` option doesn't allocate any of the specified
309 resources, it just assigns existing resources to NUMA nodes. This
310 means that one still has to use the ``-m``, ``-smp`` options to
311 allocate RAM and VCPUs respectively.
313 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
314 Information between initiator and target NUMA nodes in ACPI
315 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can
316 create memory requests, usually it has one or more processors.
317 Target NUMA node contains addressable memory.
319 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is
320 the memory hierarchy of the target NUMA node: if hierarchy is
321 'memory', the structure represents the memory performance; if
322 hierarchy is 'first-level\|second-level\|third-level', this
323 structure represents aggregated performance of memory side caches
324 for each domain. type of 'data-type' is type of data represented by
325 this structure instance: if 'hierarchy' is 'memory', 'data-type' is
326 'access\|read\|write' latency or 'access\|read\|write' bandwidth of
327 the target memory; if 'hierarchy' is
328 'first-level\|second-level\|third-level', 'data-type' is
329 'access\|read\|write' hit latency or 'access\|read\|write' hit
330 bandwidth of the target memory side cache.
332 lat is latency value in nanoseconds. bw is bandwidth value, the
333 possible value and units are NUM[M\|G\|T], mean that the bandwidth
334 value are NUM byte per second (or MB/s, GB/s or TB/s depending on
335 used suffix). Note that if latency or bandwidth value is 0, means
336 the corresponding latency or bandwidth information is not provided.
338 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory
339 belongs. size is the size of memory side cache in bytes. level is
340 the cache level described in this structure, note that the cache
341 level 0 should not be used with '\ ``hmat-cache``\ ' option.
342 associativity is the cache associativity, the possible value is
343 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
344 is the write policy. line is the cache Line size in bytes.
346 For example, the following options describe 2 NUMA nodes. Node 0 has
347 2 cpus and a ram, node 1 has only a ram. The processors in node 0
348 access memory in node 0 with access-latency 5 nanoseconds,
349 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access
350 memory in NUMA node 1 with access-latency 10 nanoseconds,
351 access-bandwidth is 100 MB/s. And for memory side cache information,
352 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB,
353 policy is write-back, the cache Line size is 8 bytes:
357 -machine hmat=on \
358 -m 2G \
359 -object memory-backend-ram,size=1G,id=m0 \
360 -object memory-backend-ram,size=1G,id=m1 \
361 -smp 2 \
362 -numa node,nodeid=0,memdev=m0 \
363 -numa node,nodeid=1,memdev=m1,initiator=0 \
364 -numa cpu,node-id=0,socket-id=0 \
365 -numa cpu,node-id=0,socket-id=1 \
366 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
367 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
368 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
369 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
370 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
371 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
372 ERST
374 DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
375 "-add-fd fd=fd,set=set[,opaque=opaque]\n"
376 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
377 SRST
378 ``-add-fd fd=fd,set=set[,opaque=opaque]``
379 Add a file descriptor to an fd set. Valid options are:
381 ``fd=fd``
382 This option defines the file descriptor of which a duplicate is
383 added to fd set. The file descriptor cannot be stdin, stdout, or
384 stderr.
386 ``set=set``
387 This option defines the ID of the fd set to add the file
388 descriptor to.
390 ``opaque=opaque``
391 This option defines a free-form string that can be used to
392 describe fd.
394 You can open an image using pre-opened file descriptors from an fd
395 set:
397 .. parsed-literal::
399 |qemu_system| \\
400 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
401 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
402 -drive file=/dev/fdset/2,index=0,media=disk
403 ERST
405 DEF("set", HAS_ARG, QEMU_OPTION_set,
406 "-set group.id.arg=value\n"
407 " set <arg> parameter for item <id> of type <group>\n"
408 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
409 SRST
410 ``-set group.id.arg=value``
411 Set parameter arg for item id of type group
412 ERST
414 DEF("global", HAS_ARG, QEMU_OPTION_global,
415 "-global driver.property=value\n"
416 "-global driver=driver,property=property,value=value\n"
417 " set a global default for a driver property\n",
418 QEMU_ARCH_ALL)
419 SRST
420 ``-global driver.prop=value``
422 ``-global driver=driver,property=property,value=value``
423 Set default value of driver's property prop to value, e.g.:
425 .. parsed-literal::
427 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img
429 In particular, you can use this to set driver properties for devices
430 which are created automatically by the machine model. To create a
431 device which is not created automatically and set properties on it,
432 use -``device``.
434 -global driver.prop=value is shorthand for -global
435 driver=driver,property=prop,value=value. The longhand syntax works
436 even when driver contains a dot.
437 ERST
439 DEF("boot", HAS_ARG, QEMU_OPTION_boot,
440 "-boot [order=drives][,once=drives][,menu=on|off]\n"
441 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
442 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
443 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
444 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n"
445 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
446 QEMU_ARCH_ALL)
447 SRST
448 ``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
449 Specify boot order drives as a string of drive letters. Valid drive
450 letters depend on the target architecture. The x86 PC uses: a, b
451 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
452 (Etherboot from network adapter 1-4), hard disk boot is the default.
453 To apply a particular boot order only on the first startup, specify
454 it via ``once``. Note that the ``order`` or ``once`` parameter
455 should not be used together with the ``bootindex`` property of
456 devices, since the firmware implementations normally do not support
457 both at the same time.
459 Interactive boot menus/prompts can be enabled via ``menu=on`` as far
460 as firmware/BIOS supports them. The default is non-interactive boot.
462 A splash picture could be passed to bios, enabling user to show it
463 as logo, when option splash=sp\_name is given and menu=on, If
464 firmware/BIOS supports them. Currently Seabios for X86 system
465 support it. limitation: The splash file could be a jpeg file or a
466 BMP file in 24 BPP format(true color). The resolution should be
467 supported by the SVGA mode, so the recommended is 320x240, 640x480,
468 800x640.
470 A timeout could be passed to bios, guest will pause for rb\_timeout
471 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
472 not reboot, qemu passes '-1' to bios by default. Currently Seabios
473 for X86 system support it.
475 Do strict boot via ``strict=on`` as far as firmware/BIOS supports
476 it. This only effects when boot priority is changed by bootindex
477 options. The default is non-strict boot.
479 .. parsed-literal::
481 # try to boot from network first, then from hard disk
482 |qemu_system_x86| -boot order=nc
483 # boot from CD-ROM first, switch back to default order after reboot
484 |qemu_system_x86| -boot once=d
485 # boot with a splash picture for 5 seconds.
486 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000
488 Note: The legacy format '-boot drives' is still supported but its
489 use is discouraged as it may be removed from future versions.
490 ERST
492 DEF("m", HAS_ARG, QEMU_OPTION_m,
493 "-m [size=]megs[,slots=n,maxmem=size]\n"
494 " configure guest RAM\n"
495 " size: initial amount of guest memory\n"
496 " slots: number of hotplug slots (default: none)\n"
497 " maxmem: maximum amount of guest memory (default: none)\n"
498 "NOTE: Some architectures might enforce a specific granularity\n",
499 QEMU_ARCH_ALL)
500 SRST
501 ``-m [size=]megs[,slots=n,maxmem=size]``
502 Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
503 Optionally, a suffix of "M" or "G" can be used to signify a value in
504 megabytes or gigabytes respectively. Optional pair slots, maxmem
505 could be used to set amount of hotpluggable memory slots and maximum
506 amount of memory. Note that maxmem must be aligned to the page size.
508 For example, the following command-line sets the guest startup RAM
509 size to 1GB, creates 3 slots to hotplug additional memory and sets
510 the maximum memory the guest can reach to 4GB:
512 .. parsed-literal::
514 |qemu_system| -m 1G,slots=3,maxmem=4G
516 If slots and maxmem are not specified, memory hotplug won't be
517 enabled and the guest startup RAM will never increase.
518 ERST
520 DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
521 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
522 SRST
523 ``-mem-path path``
524 Allocate guest RAM from a temporarily created file in path.
525 ERST
527 DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
528 "-mem-prealloc preallocate guest memory (use with -mem-path)\n",
529 QEMU_ARCH_ALL)
530 SRST
531 ``-mem-prealloc``
532 Preallocate memory when using -mem-path.
533 ERST
535 DEF("k", HAS_ARG, QEMU_OPTION_k,
536 "-k language use keyboard layout (for example 'fr' for French)\n",
537 QEMU_ARCH_ALL)
538 SRST
539 ``-k language``
540 Use keyboard layout language (for example ``fr`` for French). This
541 option is only needed where it is not easy to get raw PC keycodes
542 (e.g. on Macs, with some X11 servers or with a VNC or curses
543 display). You don't normally need to use it on PC/Linux or
544 PC/Windows hosts.
546 The available layouts are:
550 ar de-ch es fo fr-ca hu ja mk no pt-br sv
551 da en-gb et fr fr-ch is lt nl pl ru th
552 de en-us fi fr-be hr it lv nl-be pt sl tr
554 The default is ``en-us``.
555 ERST
558 HXCOMM Deprecated by -audiodev
559 DEF("audio-help", 0, QEMU_OPTION_audio_help,
560 "-audio-help show -audiodev equivalent of the currently specified audio settings\n",
561 QEMU_ARCH_ALL)
562 SRST
563 ``-audio-help``
564 Will show the -audiodev equivalent of the currently specified
565 (deprecated) environment variables.
566 ERST
568 DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
569 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
570 " specifies the audio backend to use\n"
571 " id= identifier of the backend\n"
572 " timer-period= timer period in microseconds\n"
573 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
574 " in|out.fixed-settings= use fixed settings for host audio\n"
575 " in|out.frequency= frequency to use with fixed settings\n"
576 " in|out.channels= number of channels to use with fixed settings\n"
577 " in|out.format= sample format to use with fixed settings\n"
578 " valid values: s8, s16, s32, u8, u16, u32, f32\n"
579 " in|out.voices= number of voices to use\n"
580 " in|out.buffer-length= length of buffer in microseconds\n"
581 "-audiodev none,id=id,[,prop[=value][,...]]\n"
582 " dummy driver that discards all output\n"
583 #ifdef CONFIG_AUDIO_ALSA
584 "-audiodev alsa,id=id[,prop[=value][,...]]\n"
585 " in|out.dev= name of the audio device to use\n"
586 " in|out.period-length= length of period in microseconds\n"
587 " in|out.try-poll= attempt to use poll mode\n"
588 " threshold= threshold (in microseconds) when playback starts\n"
589 #endif
590 #ifdef CONFIG_AUDIO_COREAUDIO
591 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
592 " in|out.buffer-count= number of buffers\n"
593 #endif
594 #ifdef CONFIG_AUDIO_DSOUND
595 "-audiodev dsound,id=id[,prop[=value][,...]]\n"
596 " latency= add extra latency to playback in microseconds\n"
597 #endif
598 #ifdef CONFIG_AUDIO_OSS
599 "-audiodev oss,id=id[,prop[=value][,...]]\n"
600 " in|out.dev= path of the audio device to use\n"
601 " in|out.buffer-count= number of buffers\n"
602 " in|out.try-poll= attempt to use poll mode\n"
603 " try-mmap= try using memory mapped access\n"
604 " exclusive= open device in exclusive mode\n"
605 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
606 #endif
607 #ifdef CONFIG_AUDIO_PA
608 "-audiodev pa,id=id[,prop[=value][,...]]\n"
609 " server= PulseAudio server address\n"
610 " in|out.name= source/sink device name\n"
611 " in|out.latency= desired latency in microseconds\n"
612 #endif
613 #ifdef CONFIG_AUDIO_SDL
614 "-audiodev sdl,id=id[,prop[=value][,...]]\n"
615 " in|out.buffer-count= number of buffers\n"
616 #endif
617 #ifdef CONFIG_SPICE
618 "-audiodev spice,id=id[,prop[=value][,...]]\n"
619 #endif
620 "-audiodev wav,id=id[,prop[=value][,...]]\n"
621 " path= path of wav file to record\n",
622 QEMU_ARCH_ALL)
623 SRST
624 ``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
625 Adds a new audio backend driver identified by id. There are global
626 and driver specific properties. Some values can be set differently
627 for input and output, they're marked with ``in|out.``. You can set
628 the input's property with ``in.prop`` and the output's property with
629 ``out.prop``. For example:
633 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
634 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
636 NOTE: parameter validation is known to be incomplete, in many cases
637 specifying an invalid option causes QEMU to print an error message
638 and continue emulation without sound.
640 Valid global options are:
642 ``id=identifier``
643 Identifies the audio backend.
645 ``timer-period=period``
646 Sets the timer period used by the audio subsystem in
647 microseconds. Default is 10000 (10 ms).
649 ``in|out.mixing-engine=on|off``
650 Use QEMU's mixing engine to mix all streams inside QEMU and
651 convert audio formats when not supported by the backend. When
652 off, fixed-settings must be off too. Note that disabling this
653 option means that the selected backend must support multiple
654 streams and the audio formats used by the virtual cards,
655 otherwise you'll get no sound. It's not recommended to disable
656 this option unless you want to use 5.1 or 7.1 audio, as mixing
657 engine only supports mono and stereo audio. Default is on.
659 ``in|out.fixed-settings=on|off``
660 Use fixed settings for host audio. When off, it will change
661 based on how the guest opens the sound card. In this case you
662 must not specify frequency, channels or format. Default is on.
664 ``in|out.frequency=frequency``
665 Specify the frequency to use when using fixed-settings. Default
666 is 44100Hz.
668 ``in|out.channels=channels``
669 Specify the number of channels to use when using fixed-settings.
670 Default is 2 (stereo).
672 ``in|out.format=format``
673 Specify the sample format to use when using fixed-settings.
674 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
675 ``u32``, ``f32``. Default is ``s16``.
677 ``in|out.voices=voices``
678 Specify the number of voices to use. Default is 1.
680 ``in|out.buffer-length=usecs``
681 Sets the size of the buffer in microseconds.
683 ``-audiodev none,id=id[,prop[=value][,...]]``
684 Creates a dummy backend that discards all outputs. This backend has
685 no backend specific properties.
687 ``-audiodev alsa,id=id[,prop[=value][,...]]``
688 Creates backend using the ALSA. This backend is only available on
689 Linux.
691 ALSA specific options are:
693 ``in|out.dev=device``
694 Specify the ALSA device to use for input and/or output. Default
695 is ``default``.
697 ``in|out.period-length=usecs``
698 Sets the period length in microseconds.
700 ``in|out.try-poll=on|off``
701 Attempt to use poll mode with the device. Default is on.
703 ``threshold=threshold``
704 Threshold (in microseconds) when playback starts. Default is 0.
706 ``-audiodev coreaudio,id=id[,prop[=value][,...]]``
707 Creates a backend using Apple's Core Audio. This backend is only
708 available on Mac OS and only supports playback.
710 Core Audio specific options are:
712 ``in|out.buffer-count=count``
713 Sets the count of the buffers.
715 ``-audiodev dsound,id=id[,prop[=value][,...]]``
716 Creates a backend using Microsoft's DirectSound. This backend is
717 only available on Windows and only supports playback.
719 DirectSound specific options are:
721 ``latency=usecs``
722 Add extra usecs microseconds latency to playback. Default is
723 10000 (10 ms).
725 ``-audiodev oss,id=id[,prop[=value][,...]]``
726 Creates a backend using OSS. This backend is available on most
727 Unix-like systems.
729 OSS specific options are:
731 ``in|out.dev=device``
732 Specify the file name of the OSS device to use. Default is
733 ``/dev/dsp``.
735 ``in|out.buffer-count=count``
736 Sets the count of the buffers.
738 ``in|out.try-poll=on|of``
739 Attempt to use poll mode with the device. Default is on.
741 ``try-mmap=on|off``
742 Try using memory mapped device access. Default is off.
744 ``exclusive=on|off``
745 Open the device in exclusive mode (vmix won't work in this
746 case). Default is off.
748 ``dsp-policy=policy``
749 Sets the timing policy (between 0 and 10, where smaller number
750 means smaller latency but higher CPU usage). Use -1 to use
751 buffer sizes specified by ``buffer`` and ``buffer-count``. This
752 option is ignored if you do not have OSS 4. Default is 5.
754 ``-audiodev pa,id=id[,prop[=value][,...]]``
755 Creates a backend using PulseAudio. This backend is available on
756 most systems.
758 PulseAudio specific options are:
760 ``server=server``
761 Sets the PulseAudio server to connect to.
763 ``in|out.name=sink``
764 Use the specified source/sink for recording/playback.
766 ``in|out.latency=usecs``
767 Desired latency in microseconds. The PulseAudio server will try
768 to honor this value but actual latencies may be lower or higher.
770 ``-audiodev sdl,id=id[,prop[=value][,...]]``
771 Creates a backend using SDL. This backend is available on most
772 systems, but you should use your platform's native backend if
773 possible.
775 SDL specific options are:
777 ``in|out.buffer-count=count``
778 Sets the count of the buffers.
780 ``-audiodev spice,id=id[,prop[=value][,...]]``
781 Creates a backend that sends audio through SPICE. This backend
782 requires ``-spice`` and automatically selected in that case, so
783 usually you can ignore this option. This backend has no backend
784 specific properties.
786 ``-audiodev wav,id=id[,prop[=value][,...]]``
787 Creates a backend that writes audio to a WAV file.
789 Backend specific options are:
791 ``path=path``
792 Write recorded audio into the specified file. Default is
793 ``qemu.wav``.
794 ERST
796 DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
797 "-soundhw c1,... enable audio support\n"
798 " and only specified sound cards (comma separated list)\n"
799 " use '-soundhw help' to get the list of supported cards\n"
800 " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
801 SRST
802 ``-soundhw card1[,card2,...] or -soundhw all``
803 Enable audio and selected sound hardware. Use 'help' to print all
804 available sound hardware. For example:
806 .. parsed-literal::
808 |qemu_system_x86| -soundhw sb16,adlib disk.img
809 |qemu_system_x86| -soundhw es1370 disk.img
810 |qemu_system_x86| -soundhw ac97 disk.img
811 |qemu_system_x86| -soundhw hda disk.img
812 |qemu_system_x86| -soundhw all disk.img
813 |qemu_system_x86| -soundhw help
815 Note that Linux's i810\_audio OSS kernel (for AC97) module might
816 require manually specifying clocking.
820 modprobe i810_audio clocking=48000
821 ERST
823 DEF("device", HAS_ARG, QEMU_OPTION_device,
824 "-device driver[,prop[=value][,...]]\n"
825 " add device (based on driver)\n"
826 " prop=value,... sets driver properties\n"
827 " use '-device help' to print all possible drivers\n"
828 " use '-device driver,help' to print all possible properties\n",
829 QEMU_ARCH_ALL)
830 SRST
831 ``-device driver[,prop[=value][,...]]``
832 Add device driver. prop=value sets driver properties. Valid
833 properties depend on the driver. To get help on possible drivers and
834 properties, use ``-device help`` and ``-device driver,help``.
836 Some drivers are:
838 ``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]``
839 Add an IPMI BMC. This is a simulation of a hardware management
840 interface processor that normally sits on a system. It provides a
841 watchdog and the ability to reset and power control the system. You
842 need to connect this to an IPMI interface to make it useful
844 The IPMI slave address to use for the BMC. The default is 0x20. This
845 address is the BMC's address on the I2C network of management
846 controllers. If you don't know what this means, it is safe to ignore
849 ``id=id``
850 The BMC id for interfaces to use this device.
852 ``slave_addr=val``
853 Define slave address to use for the BMC. The default is 0x20.
855 ``sdrfile=file``
856 file containing raw Sensor Data Records (SDR) data. The default
857 is none.
859 ``fruareasize=val``
860 size of a Field Replaceable Unit (FRU) area. The default is
861 1024.
863 ``frudatafile=file``
864 file containing raw Field Replaceable Unit (FRU) inventory data.
865 The default is none.
867 ``guid=uuid``
868 value for the GUID for the BMC, in standard UUID format. If this
869 is set, get "Get GUID" command to the BMC will return it.
870 Otherwise "Get GUID" will return an error.
872 ``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
873 Add a connection to an external IPMI BMC simulator. Instead of
874 locally emulating the BMC like the above item, instead connect to an
875 external entity that provides the IPMI services.
877 A connection is made to an external BMC simulator. If you do this,
878 it is strongly recommended that you use the "reconnect=" chardev
879 option to reconnect to the simulator if the connection is lost. Note
880 that if this is not used carefully, it can be a security issue, as
881 the interface has the ability to send resets, NMIs, and power off
882 the VM. It's best if QEMU makes a connection to an external
883 simulator running on a secure port on localhost, so neither the
884 simulator nor QEMU is exposed to any outside network.
886 See the "lanserv/README.vm" file in the OpenIPMI library for more
887 details on the external interface.
889 ``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
890 Add a KCS IPMI interafce on the ISA bus. This also adds a
891 corresponding ACPI and SMBIOS entries, if appropriate.
893 ``bmc=id``
894 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
895 above.
897 ``ioport=val``
898 Define the I/O address of the interface. The default is 0xca0
899 for KCS.
901 ``irq=val``
902 Define the interrupt to use. The default is 5. To disable
903 interrupts, set this to 0.
905 ``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
906 Like the KCS interface, but defines a BT interface. The default port
907 is 0xe4 and the default interrupt is 5.
909 ``-device pci-ipmi-kcs,bmc=id``
910 Add a KCS IPMI interafce on the PCI bus.
912 ``bmc=id``
913 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
915 ``-device pci-ipmi-bt,bmc=id``
916 Like the KCS interface, but defines a BT interface on the PCI bus.
917 ERST
919 DEF("name", HAS_ARG, QEMU_OPTION_name,
920 "-name string1[,process=string2][,debug-threads=on|off]\n"
921 " set the name of the guest\n"
922 " string1 sets the window title and string2 the process name\n"
923 " When debug-threads is enabled, individual threads are given a separate name\n"
924 " NOTE: The thread names are for debugging and not a stable API.\n",
925 QEMU_ARCH_ALL)
926 SRST
927 ``-name name``
928 Sets the name of the guest. This name will be displayed in the SDL
929 window caption. The name will also be used for the VNC server. Also
930 optionally set the top visible process name in Linux. Naming of
931 individual threads can also be enabled on Linux to aid debugging.
932 ERST
934 DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
935 "-uuid %08x-%04x-%04x-%04x-%012x\n"
936 " specify machine UUID\n", QEMU_ARCH_ALL)
937 SRST
938 ``-uuid uuid``
939 Set system UUID.
940 ERST
942 DEFHEADING()
944 DEFHEADING(Block device options:)
946 DEF("fda", HAS_ARG, QEMU_OPTION_fda,
947 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
948 DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
949 SRST
950 ``-fda file``
952 ``-fdb file``
953 Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in
954 the System Emulation Users Guide).
955 ERST
957 DEF("hda", HAS_ARG, QEMU_OPTION_hda,
958 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL)
959 DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
960 DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
961 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL)
962 DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
963 SRST
964 ``-hda file``
966 ``-hdb file``
968 ``-hdc file``
970 ``-hdd file``
971 Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images`
972 chapter in the System Emulation Users Guide).
973 ERST
975 DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
976 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n",
977 QEMU_ARCH_ALL)
978 SRST
979 ``-cdrom file``
980 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at
981 the same time). You can use the host CD-ROM by using ``/dev/cdrom``
982 as filename.
983 ERST
985 DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
986 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
987 " [,cache.direct=on|off][,cache.no-flush=on|off]\n"
988 " [,read-only=on|off][,auto-read-only=on|off]\n"
989 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
990 " [,driver specific parameters...]\n"
991 " configure a block backend\n", QEMU_ARCH_ALL)
992 SRST
993 ``-blockdev option[,option[,option[,...]]]``
994 Define a new block driver node. Some of the options apply to all
995 block drivers, other options are only accepted for a specific block
996 driver. See below for a list of generic options and options for the
997 most common block drivers.
999 Options that expect a reference to another node (e.g. ``file``) can
1000 be given in two ways. Either you specify the node name of an already
1001 existing node (file=node-name), or you define a new node inline,
1002 adding options for the referenced node after a dot
1003 (file.filename=path,file.aio=native).
1005 A block driver node created with ``-blockdev`` can be used for a
1006 guest device by specifying its node name for the ``drive`` property
1007 in a ``-device`` argument that defines a block device.
1009 ``Valid options for any block driver node:``
1010 ``driver``
1011 Specifies the block driver to use for the given node.
1013 ``node-name``
1014 This defines the name of the block driver node by which it
1015 will be referenced later. The name must be unique, i.e. it
1016 must not match the name of a different block driver node, or
1017 (if you use ``-drive`` as well) the ID of a drive.
1019 If no node name is specified, it is automatically generated.
1020 The generated node name is not intended to be predictable
1021 and changes between QEMU invocations. For the top level, an
1022 explicit node name must be specified.
1024 ``read-only``
1025 Open the node read-only. Guest write attempts will fail.
1027 Note that some block drivers support only read-only access,
1028 either generally or in certain configurations. In this case,
1029 the default value ``read-only=off`` does not work and the
1030 option must be specified explicitly.
1032 ``auto-read-only``
1033 If ``auto-read-only=on`` is set, QEMU may fall back to
1034 read-only usage even when ``read-only=off`` is requested, or
1035 even switch between modes as needed, e.g. depending on
1036 whether the image file is writable or whether a writing user
1037 is attached to the node.
1039 ``force-share``
1040 Override the image locking system of QEMU by forcing the
1041 node to utilize weaker shared access for permissions where
1042 it would normally request exclusive access. When there is
1043 the potential for multiple instances to have the same file
1044 open (whether this invocation of QEMU is the first or the
1045 second instance), both instances must permit shared access
1046 for the second instance to succeed at opening the file.
1048 Enabling ``force-share=on`` requires ``read-only=on``.
1050 ``cache.direct``
1051 The host page cache can be avoided with ``cache.direct=on``.
1052 This will attempt to do disk IO directly to the guest's
1053 memory. QEMU may still perform an internal copy of the data.
1055 ``cache.no-flush``
1056 In case you don't care about data integrity over host
1057 failures, you can use ``cache.no-flush=on``. This option
1058 tells QEMU that it never needs to write any data to the disk
1059 but can instead keep things in cache. If anything goes
1060 wrong, like your host losing power, the disk storage getting
1061 disconnected accidentally, etc. your image will most
1062 probably be rendered unusable.
1064 ``discard=discard``
1065 discard is one of "ignore" (or "off") or "unmap" (or "on")
1066 and controls whether ``discard`` (also known as ``trim`` or
1067 ``unmap``) requests are ignored or passed to the filesystem.
1068 Some machine types may not support discard requests.
1070 ``detect-zeroes=detect-zeroes``
1071 detect-zeroes is "off", "on" or "unmap" and enables the
1072 automatic conversion of plain zero writes by the OS to
1073 driver specific optimized zero write commands. You may even
1074 choose "unmap" if discard is set to "unmap" to allow a zero
1075 write to be converted to an ``unmap`` operation.
1077 ``Driver-specific options for file``
1078 This is the protocol-level block driver for accessing regular
1079 files.
1081 ``filename``
1082 The path to the image file in the local filesystem
1084 ``aio``
1085 Specifies the AIO backend (threads/native/io_uring,
1086 default: threads)
1088 ``locking``
1089 Specifies whether the image file is protected with Linux OFD
1090 / POSIX locks. The default is to use the Linux Open File
1091 Descriptor API if available, otherwise no lock is applied.
1092 (auto/on/off, default: auto)
1094 Example:
1098 -blockdev driver=file,node-name=disk,filename=disk.img
1100 ``Driver-specific options for raw``
1101 This is the image format block driver for raw images. It is
1102 usually stacked on top of a protocol level block driver such as
1103 ``file``.
1105 ``file``
1106 Reference to or definition of the data source block driver
1107 node (e.g. a ``file`` driver node)
1109 Example 1:
1113 -blockdev driver=file,node-name=disk_file,filename=disk.img
1114 -blockdev driver=raw,node-name=disk,file=disk_file
1116 Example 2:
1120 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1122 ``Driver-specific options for qcow2``
1123 This is the image format block driver for qcow2 images. It is
1124 usually stacked on top of a protocol level block driver such as
1125 ``file``.
1127 ``file``
1128 Reference to or definition of the data source block driver
1129 node (e.g. a ``file`` driver node)
1131 ``backing``
1132 Reference to or definition of the backing file block device
1133 (default is taken from the image file). It is allowed to
1134 pass ``null`` here in order to disable the default backing
1135 file.
1137 ``lazy-refcounts``
1138 Whether to enable the lazy refcounts feature (on/off;
1139 default is taken from the image file)
1141 ``cache-size``
1142 The maximum total size of the L2 table and refcount block
1143 caches in bytes (default: the sum of l2-cache-size and
1144 refcount-cache-size)
1146 ``l2-cache-size``
1147 The maximum size of the L2 table cache in bytes (default: if
1148 cache-size is not specified - 32M on Linux platforms, and 8M
1149 on non-Linux platforms; otherwise, as large as possible
1150 within the cache-size, while permitting the requested or the
1151 minimal refcount cache size)
1153 ``refcount-cache-size``
1154 The maximum size of the refcount block cache in bytes
1155 (default: 4 times the cluster size; or if cache-size is
1156 specified, the part of it which is not used for the L2
1157 cache)
1159 ``cache-clean-interval``
1160 Clean unused entries in the L2 and refcount caches. The
1161 interval is in seconds. The default value is 600 on
1162 supporting platforms, and 0 on other platforms. Setting it
1163 to 0 disables this feature.
1165 ``pass-discard-request``
1166 Whether discard requests to the qcow2 device should be
1167 forwarded to the data source (on/off; default: on if
1168 discard=unmap is specified, off otherwise)
1170 ``pass-discard-snapshot``
1171 Whether discard requests for the data source should be
1172 issued when a snapshot operation (e.g. deleting a snapshot)
1173 frees clusters in the qcow2 file (on/off; default: on)
1175 ``pass-discard-other``
1176 Whether discard requests for the data source should be
1177 issued on other occasions where a cluster gets freed
1178 (on/off; default: off)
1180 ``overlap-check``
1181 Which overlap checks to perform for writes to the image
1182 (none/constant/cached/all; default: cached). For details or
1183 finer granularity control refer to the QAPI documentation of
1184 ``blockdev-add``.
1186 Example 1:
1190 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1191 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1193 Example 2:
1197 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1199 ``Driver-specific options for other drivers``
1200 Please refer to the QAPI documentation of the ``blockdev-add``
1201 QMP command.
1202 ERST
1204 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1205 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1206 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1207 " [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1208 " [,werror=ignore|stop|report|enospc][,id=name]\n"
1209 " [,aio=threads|native|io_uring]\n"
1210 " [,readonly=on|off][,copy-on-read=on|off]\n"
1211 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1212 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1213 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1214 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1215 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1216 " [[,iops_size=is]]\n"
1217 " [[,group=g]]\n"
1218 " use 'file' as a drive image\n", QEMU_ARCH_ALL)
1219 SRST
1220 ``-drive option[,option[,option[,...]]]``
1221 Define a new drive. This includes creating a block driver node (the
1222 backend) as well as a guest device, and is mostly a shortcut for
1223 defining the corresponding ``-blockdev`` and ``-device`` options.
1225 ``-drive`` accepts all options that are accepted by ``-blockdev``.
1226 In addition, it knows the following options:
1228 ``file=file``
1229 This option defines which disk image (see the :ref:`disk images`
1230 chapter in the System Emulation Users Guide) to use with this drive.
1231 If the filename contains comma, you must double it (for instance,
1232 "file=my,,file" to use file "my,file").
1234 Special files such as iSCSI devices can be specified using
1235 protocol specific URLs. See the section for "Device URL Syntax"
1236 for more information.
1238 ``if=interface``
1239 This option defines on which type on interface the drive is
1240 connected. Available types are: ide, scsi, sd, mtd, floppy,
1241 pflash, virtio, none.
1243 ``bus=bus,unit=unit``
1244 These options define where is connected the drive by defining
1245 the bus number and the unit id.
1247 ``index=index``
1248 This option defines where is connected the drive by using an
1249 index in the list of available connectors of a given interface
1250 type.
1252 ``media=media``
1253 This option defines the type of the media: disk or cdrom.
1255 ``snapshot=snapshot``
1256 snapshot is "on" or "off" and controls snapshot mode for the
1257 given drive (see ``-snapshot``).
1259 ``cache=cache``
1260 cache is "none", "writeback", "unsafe", "directsync" or
1261 "writethrough" and controls how the host cache is used to access
1262 block data. This is a shortcut that sets the ``cache.direct``
1263 and ``cache.no-flush`` options (as in ``-blockdev``), and
1264 additionally ``cache.writeback``, which provides a default for
1265 the ``write-cache`` option of block guest devices (as in
1266 ``-device``). The modes correspond to the following settings:
1268 ============= =============== ============ ==============
1269 \ cache.writeback cache.direct cache.no-flush
1270 ============= =============== ============ ==============
1271 writeback on off off
1272 none on on off
1273 writethrough off off off
1274 directsync off on off
1275 unsafe on off on
1276 ============= =============== ============ ==============
1278 The default mode is ``cache=writeback``.
1280 ``aio=aio``
1281 aio is "threads", "native", or "io_uring" and selects between pthread
1282 based disk I/O, native Linux AIO, or Linux io_uring API.
1284 ``format=format``
1285 Specify which disk format will be used rather than detecting the
1286 format. Can be used to specify format=raw to avoid interpreting
1287 an untrusted format header.
1289 ``werror=action,rerror=action``
1290 Specify which action to take on write and read errors. Valid
1291 actions are: "ignore" (ignore the error and try to continue),
1292 "stop" (pause QEMU), "report" (report the error to the guest),
1293 "enospc" (pause QEMU only if the host disk is full; report the
1294 error to the guest otherwise). The default setting is
1295 ``werror=enospc`` and ``rerror=report``.
1297 ``copy-on-read=copy-on-read``
1298 copy-on-read is "on" or "off" and enables whether to copy read
1299 backing file sectors into the image file.
1301 ``bps=b,bps_rd=r,bps_wr=w``
1302 Specify bandwidth throttling limits in bytes per second, either
1303 for all request types or for reads or writes only. Small values
1304 can lead to timeouts or hangs inside the guest. A safe minimum
1305 for disks is 2 MB/s.
1307 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
1308 Specify bursts in bytes per second, either for all request types
1309 or for reads or writes only. Bursts allow the guest I/O to spike
1310 above the limit temporarily.
1312 ``iops=i,iops_rd=r,iops_wr=w``
1313 Specify request rate limits in requests per second, either for
1314 all request types or for reads or writes only.
1316 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
1317 Specify bursts in requests per second, either for all request
1318 types or for reads or writes only. Bursts allow the guest I/O to
1319 spike above the limit temporarily.
1321 ``iops_size=is``
1322 Let every is bytes of a request count as a new request for iops
1323 throttling purposes. Use this option to prevent guests from
1324 circumventing iops limits by sending fewer but larger requests.
1326 ``group=g``
1327 Join a throttling quota group with given name g. All drives that
1328 are members of the same group are accounted for together. Use
1329 this option to prevent guests from circumventing throttling
1330 limits by using many small disks instead of a single larger
1331 disk.
1333 By default, the ``cache.writeback=on`` mode is used. It will report
1334 data writes as completed as soon as the data is present in the host
1335 page cache. This is safe as long as your guest OS makes sure to
1336 correctly flush disk caches where needed. If your guest OS does not
1337 handle volatile disk write caches correctly and your host crashes or
1338 loses power, then the guest may experience data corruption.
1340 For such guests, you should consider using ``cache.writeback=off``.
1341 This means that the host page cache will be used to read and write
1342 data, but write notification will be sent to the guest only after
1343 QEMU has made sure to flush each write to the disk. Be aware that
1344 this has a major impact on performance.
1346 When using the ``-snapshot`` option, unsafe caching is always used.
1348 Copy-on-read avoids accessing the same backing file sectors
1349 repeatedly and is useful when the backing file is over a slow
1350 network. By default copy-on-read is off.
1352 Instead of ``-cdrom`` you can use:
1354 .. parsed-literal::
1356 |qemu_system| -drive file=file,index=2,media=cdrom
1358 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:
1360 .. parsed-literal::
1362 |qemu_system| -drive file=file,index=0,media=disk
1363 |qemu_system| -drive file=file,index=1,media=disk
1364 |qemu_system| -drive file=file,index=2,media=disk
1365 |qemu_system| -drive file=file,index=3,media=disk
1367 You can open an image using pre-opened file descriptors from an fd
1368 set:
1370 .. parsed-literal::
1372 |qemu_system| \\
1373 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\
1374 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\
1375 -drive file=/dev/fdset/2,index=0,media=disk
1377 You can connect a CDROM to the slave of ide0:
1379 .. parsed-literal::
1381 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom
1383 If you don't specify the "file=" argument, you define an empty
1384 drive:
1386 .. parsed-literal::
1388 |qemu_system_x86| -drive if=ide,index=1,media=cdrom
1390 Instead of ``-fda``, ``-fdb``, you can use:
1392 .. parsed-literal::
1394 |qemu_system_x86| -drive file=file,index=0,if=floppy
1395 |qemu_system_x86| -drive file=file,index=1,if=floppy
1397 By default, interface is "ide" and index is automatically
1398 incremented:
1400 .. parsed-literal::
1402 |qemu_system_x86| -drive file=a -drive file=b"
1404 is interpreted like:
1406 .. parsed-literal::
1408 |qemu_system_x86| -hda a -hdb b
1409 ERST
1411 DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1412 "-mtdblock file use 'file' as on-board Flash memory image\n",
1413 QEMU_ARCH_ALL)
1414 SRST
1415 ``-mtdblock file``
1416 Use file as on-board Flash memory image.
1417 ERST
1419 DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1420 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1421 SRST
1422 ``-sd file``
1423 Use file as SecureDigital card image.
1424 ERST
1426 DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
1427 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
1428 SRST
1429 ``-pflash file``
1430 Use file as a parallel flash image.
1431 ERST
1433 DEF("snapshot", 0, QEMU_OPTION_snapshot,
1434 "-snapshot write to temporary files instead of disk image files\n",
1435 QEMU_ARCH_ALL)
1436 SRST
1437 ``-snapshot``
1438 Write to temporary files instead of disk image files. In this case,
1439 the raw disk image you use is not written back. You can however
1440 force the write back by pressing C-a s (see the :ref:`disk images`
1441 chapter in the System Emulation Users Guide).
1442 ERST
1444 DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1445 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1446 " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n"
1447 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1448 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1449 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1450 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1451 " [[,throttling.iops-size=is]]\n"
1452 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n"
1453 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n"
1454 "-fsdev synth,id=id\n",
1455 QEMU_ARCH_ALL)
1457 SRST
1458 ``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]``
1460 ``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]``
1462 ``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]``
1464 ``-fsdev synth,id=id[,readonly=on]``
1465 Define a new file system device. Valid options are:
1467 ``local``
1468 Accesses to the filesystem are done by QEMU.
1470 ``proxy``
1471 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1473 ``synth``
1474 Synthetic filesystem, only used by QTests.
1476 ``id=id``
1477 Specifies identifier for this device.
1479 ``path=path``
1480 Specifies the export path for the file system device. Files
1481 under this path will be available to the 9p client on the guest.
1483 ``security_model=security_model``
1484 Specifies the security model to be used for this export path.
1485 Supported security models are "passthrough", "mapped-xattr",
1486 "mapped-file" and "none". In "passthrough" security model, files
1487 are stored using the same credentials as they are created on the
1488 guest. This requires QEMU to run as root. In "mapped-xattr"
1489 security model, some of the file attributes like uid, gid, mode
1490 bits and link target are stored as file attributes. For
1491 "mapped-file" these attributes are stored in the hidden
1492 .virtfs\_metadata directory. Directories exported by this
1493 security model cannot interact with other unix tools. "none"
1494 security model is same as passthrough except the sever won't
1495 report failures if it fails to set file attributes like
1496 ownership. Security model is mandatory only for local fsdriver.
1497 Other fsdrivers (like proxy) don't take security model as a
1498 parameter.
1500 ``writeout=writeout``
1501 This is an optional argument. The only supported value is
1502 "immediate". This means that host page cache will be used to
1503 read and write data but write notification will be sent to the
1504 guest only when the data has been reported as written by the
1505 storage subsystem.
1507 ``readonly=on``
1508 Enables exporting 9p share as a readonly mount for guests. By
1509 default read-write access is given.
1511 ``socket=socket``
1512 Enables proxy filesystem driver to use passed socket file for
1513 communicating with virtfs-proxy-helper(1).
1515 ``sock_fd=sock_fd``
1516 Enables proxy filesystem driver to use passed socket descriptor
1517 for communicating with virtfs-proxy-helper(1). Usually a helper
1518 like libvirt will create socketpair and pass one of the fds as
1519 sock\_fd.
1521 ``fmode=fmode``
1522 Specifies the default mode for newly created files on the host.
1523 Works only with security models "mapped-xattr" and
1524 "mapped-file".
1526 ``dmode=dmode``
1527 Specifies the default mode for newly created directories on the
1528 host. Works only with security models "mapped-xattr" and
1529 "mapped-file".
1531 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w``
1532 Specify bandwidth throttling limits in bytes per second, either
1533 for all request types or for reads or writes only.
1535 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm``
1536 Specify bursts in bytes per second, either for all request types
1537 or for reads or writes only. Bursts allow the guest I/O to spike
1538 above the limit temporarily.
1540 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w``
1541 Specify request rate limits in requests per second, either for
1542 all request types or for reads or writes only.
1544 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm``
1545 Specify bursts in requests per second, either for all request
1546 types or for reads or writes only. Bursts allow the guest I/O to
1547 spike above the limit temporarily.
1549 ``throttling.iops-size=is``
1550 Let every is bytes of a request count as a new request for iops
1551 throttling purposes.
1553 -fsdev option is used along with -device driver "virtio-9p-...".
1555 ``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag``
1556 Options for virtio-9p-... driver are:
1558 ``type``
1559 Specifies the variant to be used. Supported values are "pci",
1560 "ccw" or "device", depending on the machine type.
1562 ``fsdev=id``
1563 Specifies the id value specified along with -fsdev option.
1565 ``mount_tag=mount_tag``
1566 Specifies the tag name to be used by the guest to mount this
1567 export point.
1568 ERST
1570 DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1571 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1572 " [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1573 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n"
1574 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n"
1575 "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n",
1576 QEMU_ARCH_ALL)
1578 SRST
1579 ``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]``
1581 ``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1583 ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]``
1585 ``-virtfs synth,mount_tag=mount_tag``
1586 Define a new virtual filesystem device and expose it to the guest using
1587 a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain
1588 directory on host is made directly accessible by guest as a pass-through
1589 file system by using the 9P network protocol for communication between
1590 host and guests, if desired even accessible, shared by several guests
1591 simultaniously.
1593 Note that ``-virtfs`` is actually just a convenience shortcut for its
1594 generalized form ``-fsdev -device virtio-9p-pci``.
1596 The general form of pass-through file system options are:
1598 ``local``
1599 Accesses to the filesystem are done by QEMU.
1601 ``proxy``
1602 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1604 ``synth``
1605 Synthetic filesystem, only used by QTests.
1607 ``id=id``
1608 Specifies identifier for the filesystem device
1610 ``path=path``
1611 Specifies the export path for the file system device. Files
1612 under this path will be available to the 9p client on the guest.
1614 ``security_model=security_model``
1615 Specifies the security model to be used for this export path.
1616 Supported security models are "passthrough", "mapped-xattr",
1617 "mapped-file" and "none". In "passthrough" security model, files
1618 are stored using the same credentials as they are created on the
1619 guest. This requires QEMU to run as root. In "mapped-xattr"
1620 security model, some of the file attributes like uid, gid, mode
1621 bits and link target are stored as file attributes. For
1622 "mapped-file" these attributes are stored in the hidden
1623 .virtfs\_metadata directory. Directories exported by this
1624 security model cannot interact with other unix tools. "none"
1625 security model is same as passthrough except the sever won't
1626 report failures if it fails to set file attributes like
1627 ownership. Security model is mandatory only for local fsdriver.
1628 Other fsdrivers (like proxy) don't take security model as a
1629 parameter.
1631 ``writeout=writeout``
1632 This is an optional argument. The only supported value is
1633 "immediate". This means that host page cache will be used to
1634 read and write data but write notification will be sent to the
1635 guest only when the data has been reported as written by the
1636 storage subsystem.
1638 ``readonly=on``
1639 Enables exporting 9p share as a readonly mount for guests. By
1640 default read-write access is given.
1642 ``socket=socket``
1643 Enables proxy filesystem driver to use passed socket file for
1644 communicating with virtfs-proxy-helper(1). Usually a helper like
1645 libvirt will create socketpair and pass one of the fds as
1646 sock\_fd.
1648 ``sock_fd``
1649 Enables proxy filesystem driver to use passed 'sock\_fd' as the
1650 socket descriptor for interfacing with virtfs-proxy-helper(1).
1652 ``fmode=fmode``
1653 Specifies the default mode for newly created files on the host.
1654 Works only with security models "mapped-xattr" and
1655 "mapped-file".
1657 ``dmode=dmode``
1658 Specifies the default mode for newly created directories on the
1659 host. Works only with security models "mapped-xattr" and
1660 "mapped-file".
1662 ``mount_tag=mount_tag``
1663 Specifies the tag name to be used by the guest to mount this
1664 export point.
1666 ``multidevs=multidevs``
1667 Specifies how to deal with multiple devices being shared with a
1668 9p export. Supported behaviours are either "remap", "forbid" or
1669 "warn". The latter is the default behaviour on which virtfs 9p
1670 expects only one device to be shared with the same export, and
1671 if more than one device is shared and accessed via the same 9p
1672 export then only a warning message is logged (once) by qemu on
1673 host side. In order to avoid file ID collisions on guest you
1674 should either create a separate virtfs export for each device to
1675 be shared with guests (recommended way) or you might use "remap"
1676 instead which allows you to share multiple devices with only one
1677 export instead, which is achieved by remapping the original
1678 inode numbers from host to guest in a way that would prevent
1679 such collisions. Remapping inodes in such use cases is required
1680 because the original device IDs from host are never passed and
1681 exposed on guest. Instead all files of an export shared with
1682 virtfs always share the same device id on guest. So two files
1683 with identical inode numbers but from actually different devices
1684 on host would otherwise cause a file ID collision and hence
1685 potential misbehaviours on guest. "forbid" on the other hand
1686 assumes like "warn" that only one device is shared by the same
1687 export, however it will not only log a warning message but also
1688 deny access to additional devices on guest. Note though that
1689 "forbid" does currently not block all possible file access
1690 operations (e.g. readdir() would still return entries from other
1691 devices).
1692 ERST
1694 DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
1695 "-iscsi [user=user][,password=password]\n"
1696 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
1697 " [,initiator-name=initiator-iqn][,id=target-iqn]\n"
1698 " [,timeout=timeout]\n"
1699 " iSCSI session parameters\n", QEMU_ARCH_ALL)
1701 SRST
1702 ``-iscsi``
1703 Configure iSCSI session parameters.
1704 ERST
1706 DEFHEADING()
1708 DEFHEADING(USB options:)
1710 DEF("usb", 0, QEMU_OPTION_usb,
1711 "-usb enable on-board USB host controller (if not enabled by default)\n",
1712 QEMU_ARCH_ALL)
1713 SRST
1714 ``-usb``
1715 Enable USB emulation on machine types with an on-board USB host
1716 controller (if not enabled by default). Note that on-board USB host
1717 controllers may not support USB 3.0. In this case
1718 ``-device qemu-xhci`` can be used instead on machines with PCI.
1719 ERST
1721 DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
1722 "-usbdevice name add the host or guest USB device 'name'\n",
1723 QEMU_ARCH_ALL)
1724 SRST
1725 ``-usbdevice devname``
1726 Add the USB device devname. Note that this option is deprecated,
1727 please use ``-device usb-...`` instead. See the chapter about
1728 :ref:`Connecting USB devices` in the System Emulation Users Guide.
1730 ``mouse``
1731 Virtual Mouse. This will override the PS/2 mouse emulation when
1732 activated.
1734 ``tablet``
1735 Pointer device that uses absolute coordinates (like a
1736 touchscreen). This means QEMU is able to report the mouse
1737 position without having to grab the mouse. Also overrides the
1738 PS/2 mouse emulation when activated.
1740 ``braille``
1741 Braille device. This will use BrlAPI to display the braille
1742 output on a real or fake device.
1743 ERST
1745 DEFHEADING()
1747 DEFHEADING(Display options:)
1749 DEF("display", HAS_ARG, QEMU_OPTION_display,
1750 #if defined(CONFIG_SPICE)
1751 "-display spice-app[,gl=on|off]\n"
1752 #endif
1753 #if defined(CONFIG_SDL)
1754 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off]\n"
1755 " [,window_close=on|off][,gl=on|core|es|off]\n"
1756 #endif
1757 #if defined(CONFIG_GTK)
1758 "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
1759 #endif
1760 #if defined(CONFIG_VNC)
1761 "-display vnc=<display>[,<optargs>]\n"
1762 #endif
1763 #if defined(CONFIG_CURSES)
1764 "-display curses[,charset=<encoding>]\n"
1765 #endif
1766 #if defined(CONFIG_OPENGL)
1767 "-display egl-headless[,rendernode=<file>]\n"
1768 #endif
1769 "-display none\n"
1770 " select display backend type\n"
1771 " The default display is equivalent to\n "
1772 #if defined(CONFIG_GTK)
1773 "\"-display gtk\"\n"
1774 #elif defined(CONFIG_SDL)
1775 "\"-display sdl\"\n"
1776 #elif defined(CONFIG_COCOA)
1777 "\"-display cocoa\"\n"
1778 #elif defined(CONFIG_VNC)
1779 "\"-vnc localhost:0,to=99,id=default\"\n"
1780 #else
1781 "\"-display none\"\n"
1782 #endif
1783 , QEMU_ARCH_ALL)
1784 SRST
1785 ``-display type``
1786 Select type of display to use. This option is a replacement for the
1787 old style -sdl/-curses/... options. Use ``-display help`` to list
1788 the available display types. Valid values for type are
1790 ``sdl``
1791 Display video output via SDL (usually in a separate graphics
1792 window; see the SDL documentation for other possibilities).
1794 ``curses``
1795 Display video output via curses. For graphics device models
1796 which support a text mode, QEMU can display this output using a
1797 curses/ncurses interface. Nothing is displayed when the graphics
1798 device is in graphical mode or if the graphics device does not
1799 support a text mode. Generally only the VGA device models
1800 support text mode. The font charset used by the guest can be
1801 specified with the ``charset`` option, for example
1802 ``charset=CP850`` for IBM CP850 encoding. The default is
1803 ``CP437``.
1805 ``none``
1806 Do not display video output. The guest will still see an
1807 emulated graphics card, but its output will not be displayed to
1808 the QEMU user. This option differs from the -nographic option in
1809 that it only affects what is done with video output; -nographic
1810 also changes the destination of the serial and parallel port
1811 data.
1813 ``gtk``
1814 Display video output in a GTK window. This interface provides
1815 drop-down menus and other UI elements to configure and control
1816 the VM during runtime.
1818 ``vnc``
1819 Start a VNC server on display <arg>
1821 ``egl-headless``
1822 Offload all OpenGL operations to a local DRI device. For any
1823 graphical display, this display needs to be paired with either
1824 VNC or SPICE displays.
1826 ``spice-app``
1827 Start QEMU as a Spice server and launch the default Spice client
1828 application. The Spice server will redirect the serial consoles
1829 and QEMU monitors. (Since 4.0)
1830 ERST
1832 DEF("nographic", 0, QEMU_OPTION_nographic,
1833 "-nographic disable graphical output and redirect serial I/Os to console\n",
1834 QEMU_ARCH_ALL)
1835 SRST
1836 ``-nographic``
1837 Normally, if QEMU is compiled with graphical window support, it
1838 displays output such as guest graphics, guest console, and the QEMU
1839 monitor in a window. With this option, you can totally disable
1840 graphical output so that QEMU is a simple command line application.
1841 The emulated serial port is redirected on the console and muxed with
1842 the monitor (unless redirected elsewhere explicitly). Therefore, you
1843 can still use QEMU to debug a Linux kernel with a serial console.
1844 Use C-a h for help on switching between the console and monitor.
1845 ERST
1847 DEF("curses", 0, QEMU_OPTION_curses,
1848 "-curses shorthand for -display curses\n",
1849 QEMU_ARCH_ALL)
1850 SRST
1851 ``-curses``
1852 Normally, if QEMU is compiled with graphical window support, it
1853 displays output such as guest graphics, guest console, and the QEMU
1854 monitor in a window. With this option, QEMU can display the VGA
1855 output when in text mode using a curses/ncurses interface. Nothing
1856 is displayed in graphical mode.
1857 ERST
1859 DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
1860 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
1861 QEMU_ARCH_ALL)
1862 SRST
1863 ``-alt-grab``
1864 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
1865 this also affects the special keys (for fullscreen, monitor-mode
1866 switching, etc).
1867 ERST
1869 DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
1870 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
1871 QEMU_ARCH_ALL)
1872 SRST
1873 ``-ctrl-grab``
1874 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
1875 also affects the special keys (for fullscreen, monitor-mode
1876 switching, etc).
1877 ERST
1879 DEF("no-quit", 0, QEMU_OPTION_no_quit,
1880 "-no-quit disable SDL window close capability\n", QEMU_ARCH_ALL)
1881 SRST
1882 ``-no-quit``
1883 Disable SDL window close capability.
1884 ERST
1886 DEF("sdl", 0, QEMU_OPTION_sdl,
1887 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL)
1888 SRST
1889 ``-sdl``
1890 Enable SDL.
1891 ERST
1893 DEF("spice", HAS_ARG, QEMU_OPTION_spice,
1894 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
1895 " [,x509-key-file=<file>][,x509-key-password=<file>]\n"
1896 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
1897 " [,x509-dh-key-file=<file>][,addr=addr][,ipv4|ipv6|unix]\n"
1898 " [,tls-ciphers=<list>]\n"
1899 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
1900 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
1901 " [,sasl][,password=<secret>][,disable-ticketing]\n"
1902 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
1903 " [,jpeg-wan-compression=[auto|never|always]]\n"
1904 " [,zlib-glz-wan-compression=[auto|never|always]]\n"
1905 " [,streaming-video=[off|all|filter]][,disable-copy-paste]\n"
1906 " [,disable-agent-file-xfer][,agent-mouse=[on|off]]\n"
1907 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
1908 " [,gl=[on|off]][,rendernode=<file>]\n"
1909 " enable spice\n"
1910 " at least one of {port, tls-port} is mandatory\n",
1911 QEMU_ARCH_ALL)
1912 SRST
1913 ``-spice option[,option[,...]]``
1914 Enable the spice remote desktop protocol. Valid options are
1916 ``port=<nr>``
1917 Set the TCP port spice is listening on for plaintext channels.
1919 ``addr=<addr>``
1920 Set the IP address spice is listening on. Default is any
1921 address.
1923 ``ipv4``; \ ``ipv6``; \ ``unix``
1924 Force using the specified IP version.
1926 ``password=<secret>``
1927 Set the password you need to authenticate.
1929 ``sasl``
1930 Require that the client use SASL to authenticate with the spice.
1931 The exact choice of authentication method used is controlled
1932 from the system / user's SASL configuration file for the 'qemu'
1933 service. This is typically found in /etc/sasl2/qemu.conf. If
1934 running QEMU as an unprivileged user, an environment variable
1935 SASL\_CONF\_PATH can be used to make it search alternate
1936 locations for the service config. While some SASL auth methods
1937 can also provide data encryption (eg GSSAPI), it is recommended
1938 that SASL always be combined with the 'tls' and 'x509' settings
1939 to enable use of SSL and server certificates. This ensures a
1940 data encryption preventing compromise of authentication
1941 credentials.
1943 ``disable-ticketing``
1944 Allow client connects without authentication.
1946 ``disable-copy-paste``
1947 Disable copy paste between the client and the guest.
1949 ``disable-agent-file-xfer``
1950 Disable spice-vdagent based file-xfer between the client and the
1951 guest.
1953 ``tls-port=<nr>``
1954 Set the TCP port spice is listening on for encrypted channels.
1956 ``x509-dir=<dir>``
1957 Set the x509 file directory. Expects same filenames as -vnc
1958 $display,x509=$dir
1960 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>``
1961 The x509 file names can also be configured individually.
1963 ``tls-ciphers=<list>``
1964 Specify which ciphers to use.
1966 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]``
1967 Force specific channel to be used with or without TLS
1968 encryption. The options can be specified multiple times to
1969 configure multiple channels. The special name "default" can be
1970 used to set the default mode. For channels which are not
1971 explicitly forced into one mode the spice client is allowed to
1972 pick tls/plaintext as he pleases.
1974 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]``
1975 Configure image compression (lossless). Default is auto\_glz.
1977 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]``
1978 Configure wan image compression (lossy for slow links). Default
1979 is auto.
1981 ``streaming-video=[off|all|filter]``
1982 Configure video stream detection. Default is off.
1984 ``agent-mouse=[on|off]``
1985 Enable/disable passing mouse events via vdagent. Default is on.
1987 ``playback-compression=[on|off]``
1988 Enable/disable audio stream compression (using celt 0.5.1).
1989 Default is on.
1991 ``seamless-migration=[on|off]``
1992 Enable/disable spice seamless migration. Default is off.
1994 ``gl=[on|off]``
1995 Enable/disable OpenGL context. Default is off.
1997 ``rendernode=<file>``
1998 DRM render node for OpenGL rendering. If not specified, it will
1999 pick the first available. (Since 2.9)
2000 ERST
2002 DEF("portrait", 0, QEMU_OPTION_portrait,
2003 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n",
2004 QEMU_ARCH_ALL)
2005 SRST
2006 ``-portrait``
2007 Rotate graphical output 90 deg left (only PXA LCD).
2008 ERST
2010 DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
2011 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n",
2012 QEMU_ARCH_ALL)
2013 SRST
2014 ``-rotate deg``
2015 Rotate graphical output some deg left (only PXA LCD).
2016 ERST
2018 DEF("vga", HAS_ARG, QEMU_OPTION_vga,
2019 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
2020 " select video card type\n", QEMU_ARCH_ALL)
2021 SRST
2022 ``-vga type``
2023 Select type of VGA card to emulate. Valid values for type are
2025 ``cirrus``
2026 Cirrus Logic GD5446 Video card. All Windows versions starting
2027 from Windows 95 should recognize and use this graphic card. For
2028 optimal performances, use 16 bit color depth in the guest and
2029 the host OS. (This card was the default before QEMU 2.2)
2031 ``std``
2032 Standard VGA card with Bochs VBE extensions. If your guest OS
2033 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
2034 you want to use high resolution modes (>= 1280x1024x16) then you
2035 should use this option. (This card is the default since QEMU
2036 2.2)
2038 ``vmware``
2039 VMWare SVGA-II compatible adapter. Use it if you have
2040 sufficiently recent XFree86/XOrg server or Windows guest with a
2041 driver for this card.
2043 ``qxl``
2044 QXL paravirtual graphic card. It is VGA compatible (including
2045 VESA 2.0 VBE support). Works best with qxl guest drivers
2046 installed though. Recommended choice when using the spice
2047 protocol.
2049 ``tcx``
2050 (sun4m only) Sun TCX framebuffer. This is the default
2051 framebuffer for sun4m machines and offers both 8-bit and 24-bit
2052 colour depths at a fixed resolution of 1024x768.
2054 ``cg3``
2055 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit
2056 framebuffer for sun4m machines available in both 1024x768
2057 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people
2058 wishing to run older Solaris versions.
2060 ``virtio``
2061 Virtio VGA card.
2063 ``none``
2064 Disable VGA card.
2065 ERST
2067 DEF("full-screen", 0, QEMU_OPTION_full_screen,
2068 "-full-screen start in full screen\n", QEMU_ARCH_ALL)
2069 SRST
2070 ``-full-screen``
2071 Start in full screen.
2072 ERST
2074 DEF("g", HAS_ARG, QEMU_OPTION_g ,
2075 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n",
2076 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K)
2077 SRST
2078 ``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]``
2079 Set the initial graphical resolution and depth (PPC, SPARC only).
2081 For PPC the default is 800x600x32.
2083 For SPARC with the TCX graphics device, the default is 1024x768x8
2084 with the option of 1024x768x24. For cgthree, the default is
2085 1024x768x8 with the option of 1152x900x8 for people who wish to use
2086 OBP.
2087 ERST
2089 DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
2090 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
2091 SRST
2092 ``-vnc display[,option[,option[,...]]]``
2093 Normally, if QEMU is compiled with graphical window support, it
2094 displays output such as guest graphics, guest console, and the QEMU
2095 monitor in a window. With this option, you can have QEMU listen on
2096 VNC display display and redirect the VGA display over the VNC
2097 session. It is very useful to enable the usb tablet device when
2098 using this option (option ``-device usb-tablet``). When using the
2099 VNC display, you must use the ``-k`` parameter to set the keyboard
2100 layout if you are not using en-us. Valid syntax for the display is
2102 ``to=L``
2103 With this option, QEMU will try next available VNC displays,
2104 until the number L, if the origianlly defined "-vnc display" is
2105 not available, e.g. port 5900+display is already used by another
2106 application. By default, to=0.
2108 ``host:d``
2109 TCP connections will only be allowed from host on display d. By
2110 convention the TCP port is 5900+d. Optionally, host can be
2111 omitted in which case the server will accept connections from
2112 any host.
2114 ``unix:path``
2115 Connections will be allowed over UNIX domain sockets where path
2116 is the location of a unix socket to listen for connections on.
2118 ``none``
2119 VNC is initialized but not started. The monitor ``change``
2120 command can be used to later start the VNC server.
2122 Following the display value there may be one or more option flags
2123 separated by commas. Valid options are
2125 ``reverse``
2126 Connect to a listening VNC client via a "reverse" connection.
2127 The client is specified by the display. For reverse network
2128 connections (host:d,``reverse``), the d argument is a TCP port
2129 number, not a display number.
2131 ``websocket``
2132 Opens an additional TCP listening port dedicated to VNC
2133 Websocket connections. If a bare websocket option is given, the
2134 Websocket port is 5700+display. An alternative port can be
2135 specified with the syntax ``websocket``\ =port.
2137 If host is specified connections will only be allowed from this
2138 host. It is possible to control the websocket listen address
2139 independently, using the syntax ``websocket``\ =host:port.
2141 If no TLS credentials are provided, the websocket connection
2142 runs in unencrypted mode. If TLS credentials are provided, the
2143 websocket connection requires encrypted client connections.
2145 ``password``
2146 Require that password based authentication is used for client
2147 connections.
2149 The password must be set separately using the ``set_password``
2150 command in the :ref:`QEMU monitor`. The
2151 syntax to change your password is:
2152 ``set_password <protocol> <password>`` where <protocol> could be
2153 either "vnc" or "spice".
2155 If you would like to change <protocol> password expiration, you
2156 should use ``expire_password <protocol> <expiration-time>``
2157 where expiration time could be one of the following options:
2158 now, never, +seconds or UNIX time of expiration, e.g. +60 to
2159 make password expire in 60 seconds, or 1335196800 to make
2160 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for
2161 this date and time).
2163 You can also use keywords "now" or "never" for the expiration
2164 time to allow <protocol> password to expire immediately or never
2165 expire.
2167 ``tls-creds=ID``
2168 Provides the ID of a set of TLS credentials to use to secure the
2169 VNC server. They will apply to both the normal VNC server socket
2170 and the websocket socket (if enabled). Setting TLS credentials
2171 will cause the VNC server socket to enable the VeNCrypt auth
2172 mechanism. The credentials should have been previously created
2173 using the ``-object tls-creds`` argument.
2175 ``tls-authz=ID``
2176 Provides the ID of the QAuthZ authorization object against which
2177 the client's x509 distinguished name will validated. This object
2178 is only resolved at time of use, so can be deleted and recreated
2179 on the fly while the VNC server is active. If missing, it will
2180 default to denying access.
2182 ``sasl``
2183 Require that the client use SASL to authenticate with the VNC
2184 server. The exact choice of authentication method used is
2185 controlled from the system / user's SASL configuration file for
2186 the 'qemu' service. This is typically found in
2187 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
2188 an environment variable SASL\_CONF\_PATH can be used to make it
2189 search alternate locations for the service config. While some
2190 SASL auth methods can also provide data encryption (eg GSSAPI),
2191 it is recommended that SASL always be combined with the 'tls'
2192 and 'x509' settings to enable use of SSL and server
2193 certificates. This ensures a data encryption preventing
2194 compromise of authentication credentials. See the
2195 :ref:`VNC security` section in the System Emulation Users Guide
2196 for details on using SASL authentication.
2198 ``sasl-authz=ID``
2199 Provides the ID of the QAuthZ authorization object against which
2200 the client's SASL username will validated. This object is only
2201 resolved at time of use, so can be deleted and recreated on the
2202 fly while the VNC server is active. If missing, it will default
2203 to denying access.
2205 ``acl``
2206 Legacy method for enabling authorization of clients against the
2207 x509 distinguished name and SASL username. It results in the
2208 creation of two ``authz-list`` objects with IDs of
2209 ``vnc.username`` and ``vnc.x509dname``. The rules for these
2210 objects must be configured with the HMP ACL commands.
2212 This option is deprecated and should no longer be used. The new
2213 ``sasl-authz`` and ``tls-authz`` options are a replacement.
2215 ``lossy``
2216 Enable lossy compression methods (gradient, JPEG, ...). If this
2217 option is set, VNC client may receive lossy framebuffer updates
2218 depending on its encoding settings. Enabling this option can
2219 save a lot of bandwidth at the expense of quality.
2221 ``non-adaptive``
2222 Disable adaptive encodings. Adaptive encodings are enabled by
2223 default. An adaptive encoding will try to detect frequently
2224 updated screen regions, and send updates in these regions using
2225 a lossy encoding (like JPEG). This can be really helpful to save
2226 bandwidth when playing videos. Disabling adaptive encodings
2227 restores the original static behavior of encodings like Tight.
2229 ``share=[allow-exclusive|force-shared|ignore]``
2230 Set display sharing policy. 'allow-exclusive' allows clients to
2231 ask for exclusive access. As suggested by the rfb spec this is
2232 implemented by dropping other connections. Connecting multiple
2233 clients in parallel requires all clients asking for a shared
2234 session (vncviewer: -shared switch). This is the default.
2235 'force-shared' disables exclusive client access. Useful for
2236 shared desktop sessions, where you don't want someone forgetting
2237 specify -shared disconnect everybody else. 'ignore' completely
2238 ignores the shared flag and allows everybody connect
2239 unconditionally. Doesn't conform to the rfb spec but is
2240 traditional QEMU behavior.
2242 ``key-delay-ms``
2243 Set keyboard delay, for key down and key up events, in
2244 milliseconds. Default is 10. Keyboards are low-bandwidth
2245 devices, so this slowdown can help the device and guest to keep
2246 up and not lose events in case events are arriving in bulk.
2247 Possible causes for the latter are flaky network connections, or
2248 scripts for automated testing.
2250 ``audiodev=audiodev``
2251 Use the specified audiodev when the VNC client requests audio
2252 transmission. When not using an -audiodev argument, this option
2253 must be omitted, otherwise is must be present and specify a
2254 valid audiodev.
2256 ``power-control``
2257 Permit the remote client to issue shutdown, reboot or reset power
2258 control requests.
2259 ERST
2261 ARCHHEADING(, QEMU_ARCH_I386)
2263 ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2265 DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2266 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n",
2267 QEMU_ARCH_I386)
2268 SRST
2269 ``-win2k-hack``
2270 Use it when installing Windows 2000 to avoid a disk full bug. After
2271 Windows 2000 is installed, you no longer need this option (this
2272 option slows down the IDE transfers).
2273 ERST
2275 DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2276 "-no-fd-bootchk disable boot signature checking for floppy disks\n",
2277 QEMU_ARCH_I386)
2278 SRST
2279 ``-no-fd-bootchk``
2280 Disable boot signature checking for floppy disks in BIOS. May be
2281 needed to boot from old floppy disks.
2282 ERST
2284 DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
2285 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2286 SRST
2287 ``-no-acpi``
2288 Disable ACPI (Advanced Configuration and Power Interface) support.
2289 Use it if your guest OS complains about ACPI problems (PC target
2290 machine only).
2291 ERST
2293 DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
2294 "-no-hpet disable HPET\n", QEMU_ARCH_I386)
2295 SRST
2296 ``-no-hpet``
2297 Disable HPET support.
2298 ERST
2300 DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2301 "-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"
2302 " ACPI table description\n", QEMU_ARCH_I386)
2303 SRST
2304 ``-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]...]``
2305 Add ACPI table with specified header fields and context from
2306 specified files. For file=, take whole ACPI table from the specified
2307 files, including all ACPI headers (possible overridden by other
2308 options). For data=, only data portion of the table is used, all
2309 header information is specified in the command line. If a SLIC table
2310 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
2311 fields will override the same in the RSDT and the FADT (a.k.a.
2312 FACP), in order to ensure the field matches required by the
2313 Microsoft SLIC spec and the ACPI spec.
2314 ERST
2316 DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2317 "-smbios file=binary\n"
2318 " load SMBIOS entry from binary file\n"
2319 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2320 " [,uefi=on|off]\n"
2321 " specify SMBIOS type 0 fields\n"
2322 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2323 " [,uuid=uuid][,sku=str][,family=str]\n"
2324 " specify SMBIOS type 1 fields\n"
2325 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2326 " [,asset=str][,location=str]\n"
2327 " specify SMBIOS type 2 fields\n"
2328 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2329 " [,sku=str]\n"
2330 " specify SMBIOS type 3 fields\n"
2331 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2332 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
2333 " specify SMBIOS type 4 fields\n"
2334 "-smbios type=11[,value=str][,path=filename]\n"
2335 " specify SMBIOS type 11 fields\n"
2336 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2337 " [,asset=str][,part=str][,speed=%d]\n"
2338 " specify SMBIOS type 17 fields\n",
2339 QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2340 SRST
2341 ``-smbios file=binary``
2342 Load SMBIOS entry from binary file.
2344 ``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]``
2345 Specify SMBIOS type 0 fields
2347 ``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]``
2348 Specify SMBIOS type 1 fields
2350 ``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]``
2351 Specify SMBIOS type 2 fields
2353 ``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
2354 Specify SMBIOS type 3 fields
2356 ``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]``
2357 Specify SMBIOS type 4 fields
2359 ``-smbios type=11[,value=str][,path=filename]``
2360 Specify SMBIOS type 11 fields
2362 This argument can be repeated multiple times, and values are added in the order they are parsed.
2363 Applications intending to use OEM strings data are encouraged to use their application name as
2364 a prefix for the value string. This facilitates passing information for multiple applications
2365 concurrently.
2367 The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax
2368 loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes.
2370 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to
2371 the SMBIOS table in the order in which they appear.
2373 Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535
2374 bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the
2375 guest. Instead it should be used as a indicator to inform the guest where to locate the real
2376 data set, for example, by specifying the serial ID of a block device.
2378 An example passing three strings is
2380 .. parsed-literal::
2382 -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\
2383 value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\
2384 path=/some/file/with/oemstringsdata.txt
2386 In the guest OS this is visible with the ``dmidecode`` command
2388 .. parsed-literal::
2390 $ dmidecode -t 11
2391 Handle 0x0E00, DMI type 11, 5 bytes
2392 OEM Strings
2393 String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/
2394 String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os
2395 String 3: myapp:some extra data
2398 ``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]``
2399 Specify SMBIOS type 17 fields
2400 ERST
2402 DEFHEADING()
2404 DEFHEADING(Network options:)
2406 DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2407 #ifdef CONFIG_SLIRP
2408 "-netdev user,id=str[,ipv4[=on|off]][,net=addr[/mask]][,host=addr]\n"
2409 " [,ipv6[=on|off]][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2410 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2411 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2412 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2413 #ifndef _WIN32
2414 "[,smb=dir[,smbserver=addr]]\n"
2415 #endif
2416 " configure a user mode network backend with ID 'str',\n"
2417 " its DHCP server and optional services\n"
2418 #endif
2419 #ifdef _WIN32
2420 "-netdev tap,id=str,ifname=name\n"
2421 " configure a host TAP network backend with ID 'str'\n"
2422 #else
2423 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2424 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2425 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2426 " [,poll-us=n]\n"
2427 " configure a host TAP network backend with ID 'str'\n"
2428 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2429 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2430 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2431 " to deconfigure it\n"
2432 " use '[down]script=no' to disable script execution\n"
2433 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2434 " configure it\n"
2435 " use 'fd=h' to connect to an already opened TAP interface\n"
2436 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2437 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2438 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2439 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2440 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2441 " use vhost=on to enable experimental in kernel accelerator\n"
2442 " (only has effect for virtio guests which use MSIX)\n"
2443 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2444 " use 'vhostfd=h' to connect to an already opened vhost net device\n"
2445 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2446 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2447 " use 'poll-us=n' to speciy the maximum number of microseconds that could be\n"
2448 " spent on busy polling for vhost net\n"
2449 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2450 " configure a host TAP network backend with ID 'str' that is\n"
2451 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2452 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2453 #endif
2454 #ifdef __linux__
2455 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2456 " [,rxsession=rxsession],txsession=txsession[,ipv6=on/off][,udp=on/off]\n"
2457 " [,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie]\n"
2458 " [,rxcookie=rxcookie][,offset=offset]\n"
2459 " configure a network backend with ID 'str' connected to\n"
2460 " an Ethernet over L2TPv3 pseudowire.\n"
2461 " Linux kernel 3.3+ as well as most routers can talk\n"
2462 " L2TPv3. This transport allows connecting a VM to a VM,\n"
2463 " VM to a router and even VM to Host. It is a nearly-universal\n"
2464 " standard (RFC3931). Note - this implementation uses static\n"
2465 " pre-configured tunnels (same as the Linux kernel).\n"
2466 " use 'src=' to specify source address\n"
2467 " use 'dst=' to specify destination address\n"
2468 " use 'udp=on' to specify udp encapsulation\n"
2469 " use 'srcport=' to specify source udp port\n"
2470 " use 'dstport=' to specify destination udp port\n"
2471 " use 'ipv6=on' to force v6\n"
2472 " L2TPv3 uses cookies to prevent misconfiguration as\n"
2473 " well as a weak security measure\n"
2474 " use 'rxcookie=0x012345678' to specify a rxcookie\n"
2475 " use 'txcookie=0x012345678' to specify a txcookie\n"
2476 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2477 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2478 " use 'pincounter=on' to work around broken counter handling in peer\n"
2479 " use 'offset=X' to add an extra offset between header and data\n"
2480 #endif
2481 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2482 " configure a network backend to connect to another network\n"
2483 " using a socket connection\n"
2484 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2485 " configure a network backend to connect to a multicast maddr and port\n"
2486 " use 'localaddr=addr' to specify the host address to send packets from\n"
2487 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2488 " configure a network backend to connect to another network\n"
2489 " using an UDP tunnel\n"
2490 #ifdef CONFIG_VDE
2491 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2492 " configure a network backend to connect to port 'n' of a vde switch\n"
2493 " running on host and listening for incoming connections on 'socketpath'.\n"
2494 " Use group 'groupname' and mode 'octalmode' to change default\n"
2495 " ownership and permissions for communication port.\n"
2496 #endif
2497 #ifdef CONFIG_NETMAP
2498 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2499 " attach to the existing netmap-enabled network interface 'name', or to a\n"
2500 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2501 " netmap device, defaults to '/dev/netmap')\n"
2502 #endif
2503 #ifdef CONFIG_POSIX
2504 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2505 " configure a vhost-user network, backed by a chardev 'dev'\n"
2506 #endif
2507 #ifdef __linux__
2508 "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n"
2509 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n"
2510 #endif
2511 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2512 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2513 DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2514 "-nic [tap|bridge|"
2515 #ifdef CONFIG_SLIRP
2516 "user|"
2517 #endif
2518 #ifdef __linux__
2519 "l2tpv3|"
2520 #endif
2521 #ifdef CONFIG_VDE
2522 "vde|"
2523 #endif
2524 #ifdef CONFIG_NETMAP
2525 "netmap|"
2526 #endif
2527 #ifdef CONFIG_POSIX
2528 "vhost-user|"
2529 #endif
2530 "socket][,option][,...][mac=macaddr]\n"
2531 " initialize an on-board / default host NIC (using MAC address\n"
2532 " macaddr) and connect it to the given host network backend\n"
2533 "-nic none use it alone to have zero network devices (the default is to\n"
2534 " provided a 'user' network connection)\n",
2535 QEMU_ARCH_ALL)
2536 DEF("net", HAS_ARG, QEMU_OPTION_net,
2537 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2538 " configure or create an on-board (or machine default) NIC and\n"
2539 " connect it to hub 0 (please use -nic unless you need a hub)\n"
2540 "-net ["
2541 #ifdef CONFIG_SLIRP
2542 "user|"
2543 #endif
2544 "tap|"
2545 "bridge|"
2546 #ifdef CONFIG_VDE
2547 "vde|"
2548 #endif
2549 #ifdef CONFIG_NETMAP
2550 "netmap|"
2551 #endif
2552 "socket][,option][,option][,...]\n"
2553 " old way to initialize a host network interface\n"
2554 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
2555 SRST
2556 ``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]``
2557 This option is a shortcut for configuring both the on-board
2558 (default) guest NIC hardware and the host network backend in one go.
2559 The host backend options are the same as with the corresponding
2560 ``-netdev`` options below. The guest NIC model can be set with
2561 ``model=modelname``. Use ``model=help`` to list the available device
2562 types. The hardware MAC address can be set with ``mac=macaddr``.
2564 The following two example do exactly the same, to show how ``-nic``
2565 can be used to shorten the command line length:
2567 .. parsed-literal::
2569 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
2570 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
2572 ``-nic none``
2573 Indicate that no network devices should be configured. It is used to
2574 override the default configuration (default NIC with "user" host
2575 network backend) which is activated if no other networking options
2576 are provided.
2578 ``-netdev user,id=id[,option][,option][,...]``
2579 Configure user mode host network backend which requires no
2580 administrator privilege to run. Valid options are:
2582 ``id=id``
2583 Assign symbolic name for use in monitor commands.
2585 ``ipv4=on|off and ipv6=on|off``
2586 Specify that either IPv4 or IPv6 must be enabled. If neither is
2587 specified both protocols are enabled.
2589 ``net=addr[/mask]``
2590 Set IP network address the guest will see. Optionally specify
2591 the netmask, either in the form a.b.c.d or as number of valid
2592 top-most bits. Default is 10.0.2.0/24.
2594 ``host=addr``
2595 Specify the guest-visible address of the host. Default is the
2596 2nd IP in the guest network, i.e. x.x.x.2.
2598 ``ipv6-net=addr[/int]``
2599 Set IPv6 network address the guest will see (default is
2600 fec0::/64). The network prefix is given in the usual hexadecimal
2601 IPv6 address notation. The prefix size is optional, and is given
2602 as the number of valid top-most bits (default is 64).
2604 ``ipv6-host=addr``
2605 Specify the guest-visible IPv6 address of the host. Default is
2606 the 2nd IPv6 in the guest network, i.e. xxxx::2.
2608 ``restrict=on|off``
2609 If this option is enabled, the guest will be isolated, i.e. it
2610 will not be able to contact the host and no guest IP packets
2611 will be routed over the host to the outside. This option does
2612 not affect any explicitly set forwarding rules.
2614 ``hostname=name``
2615 Specifies the client hostname reported by the built-in DHCP
2616 server.
2618 ``dhcpstart=addr``
2619 Specify the first of the 16 IPs the built-in DHCP server can
2620 assign. Default is the 15th to 31st IP in the guest network,
2621 i.e. x.x.x.15 to x.x.x.31.
2623 ``dns=addr``
2624 Specify the guest-visible address of the virtual nameserver. The
2625 address must be different from the host address. Default is the
2626 3rd IP in the guest network, i.e. x.x.x.3.
2628 ``ipv6-dns=addr``
2629 Specify the guest-visible address of the IPv6 virtual
2630 nameserver. The address must be different from the host address.
2631 Default is the 3rd IP in the guest network, i.e. xxxx::3.
2633 ``dnssearch=domain``
2634 Provides an entry for the domain-search list sent by the
2635 built-in DHCP server. More than one domain suffix can be
2636 transmitted by specifying this option multiple times. If
2637 supported, this will cause the guest to automatically try to
2638 append the given domain suffix(es) in case a domain name can not
2639 be resolved.
2641 Example:
2643 .. parsed-literal::
2645 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
2647 ``domainname=domain``
2648 Specifies the client domain name reported by the built-in DHCP
2649 server.
2651 ``tftp=dir``
2652 When using the user mode network stack, activate a built-in TFTP
2653 server. The files in dir will be exposed as the root of a TFTP
2654 server. The TFTP client on the guest must be configured in
2655 binary mode (use the command ``bin`` of the Unix TFTP client).
2657 ``tftp-server-name=name``
2658 In BOOTP reply, broadcast name as the "TFTP server name"
2659 (RFC2132 option 66). This can be used to advise the guest to
2660 load boot files or configurations from a different server than
2661 the host address.
2663 ``bootfile=file``
2664 When using the user mode network stack, broadcast file as the
2665 BOOTP filename. In conjunction with ``tftp``, this can be used
2666 to network boot a guest from a local directory.
2668 Example (using pxelinux):
2670 .. parsed-literal::
2672 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\
2673 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
2675 ``smb=dir[,smbserver=addr]``
2676 When using the user mode network stack, activate a built-in SMB
2677 server so that Windows OSes can access to the host files in
2678 ``dir`` transparently. The IP address of the SMB server can be
2679 set to addr. By default the 4th IP in the guest network is used,
2680 i.e. x.x.x.4.
2682 In the guest Windows OS, the line:
2686 10.0.2.4 smbserver
2688 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows
2689 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows
2690 NT/2000).
2692 Then ``dir`` can be accessed in ``\\smbserver\qemu``.
2694 Note that a SAMBA server must be installed on the host OS.
2696 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
2697 Redirect incoming TCP or UDP connections to the host port
2698 hostport to the guest IP address guestaddr on guest port
2699 guestport. If guestaddr is not specified, its value is x.x.x.15
2700 (default first address given by the built-in DHCP server). By
2701 specifying hostaddr, the rule can be bound to a specific host
2702 interface. If no connection type is set, TCP is used. This
2703 option can be given multiple times.
2705 For example, to redirect host X11 connection from screen 1 to
2706 guest screen 0, use the following:
2708 .. parsed-literal::
2710 # on the host
2711 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
2712 # this host xterm should open in the guest X11 server
2713 xterm -display :1
2715 To redirect telnet connections from host port 5555 to telnet
2716 port on the guest, use the following:
2718 .. parsed-literal::
2720 # on the host
2721 |qemu_system| -nic user,hostfwd=tcp::5555-:23
2722 telnet localhost 5555
2724 Then when you use on the host ``telnet localhost 5555``, you
2725 connect to the guest telnet server.
2727 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command``
2728 Forward guest TCP connections to the IP address server on port
2729 port to the character device dev or to a program executed by
2730 cmd:command which gets spawned for each connection. This option
2731 can be given multiple times.
2733 You can either use a chardev directly and have that one used
2734 throughout QEMU's lifetime, like in the following example:
2736 .. parsed-literal::
2738 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
2739 # the guest accesses it
2740 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
2742 Or you can execute a command on every TCP connection established
2743 by the guest, so that QEMU behaves similar to an inetd process
2744 for that virtual server:
2746 .. parsed-literal::
2748 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
2749 # and connect the TCP stream to its stdin/stdout
2750 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
2752 ``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
2753 Configure a host TAP network backend with ID id.
2755 Use the network script file to configure it and the network script
2756 dfile to deconfigure it. If name is not provided, the OS
2757 automatically provides one. The default network configure script is
2758 ``/etc/qemu-ifup`` and the default network deconfigure script is
2759 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
2760 disable script execution.
2762 If running QEMU as an unprivileged user, use the network helper
2763 to configure the TAP interface and attach it to the bridge.
2764 The default network helper executable is
2765 ``/path/to/qemu-bridge-helper`` and the default bridge device is
2766 ``br0``.
2768 ``fd``\ =h can be used to specify the handle of an already opened
2769 host TAP interface.
2771 Examples:
2773 .. parsed-literal::
2775 #launch a QEMU instance with the default network script
2776 |qemu_system| linux.img -nic tap
2778 .. parsed-literal::
2780 #launch a QEMU instance with two NICs, each one connected
2781 #to a TAP device
2782 |qemu_system| linux.img \\
2783 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\
2784 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
2786 .. parsed-literal::
2788 #launch a QEMU instance with the default network helper to
2789 #connect a TAP device to bridge br0
2790 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
2791 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
2793 ``-netdev bridge,id=id[,br=bridge][,helper=helper]``
2794 Connect a host TAP network interface to a host bridge device.
2796 Use the network helper helper to configure the TAP interface and
2797 attach it to the bridge. The default network helper executable is
2798 ``/path/to/qemu-bridge-helper`` and the default bridge device is
2799 ``br0``.
2801 Examples:
2803 .. parsed-literal::
2805 #launch a QEMU instance with the default network helper to
2806 #connect a TAP device to bridge br0
2807 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
2809 .. parsed-literal::
2811 #launch a QEMU instance with the default network helper to
2812 #connect a TAP device to bridge qemubr0
2813 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
2815 ``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
2816 This host network backend can be used to connect the guest's network
2817 to another QEMU virtual machine using a TCP socket connection. If
2818 ``listen`` is specified, QEMU waits for incoming connections on port
2819 (host is optional). ``connect`` is used to connect to another QEMU
2820 instance using the ``listen`` option. ``fd``\ =h specifies an
2821 already opened TCP socket.
2823 Example:
2825 .. parsed-literal::
2827 # launch a first QEMU instance
2828 |qemu_system| linux.img \\
2829 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
2830 -netdev socket,id=n1,listen=:1234
2831 # connect the network of this instance to the network of the first instance
2832 |qemu_system| linux.img \\
2833 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
2834 -netdev socket,id=n2,connect=127.0.0.1:1234
2836 ``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]``
2837 Configure a socket host network backend to share the guest's network
2838 traffic with another QEMU virtual machines using a UDP multicast
2839 socket, effectively making a bus for every QEMU with same multicast
2840 address maddr and port. NOTES:
2842 1. Several QEMU can be running on different hosts and share same bus
2843 (assuming correct multicast setup for these hosts).
2845 2. mcast support is compatible with User Mode Linux (argument
2846 ``ethN=mcast``), see http://user-mode-linux.sf.net.
2848 3. Use ``fd=h`` to specify an already opened UDP multicast socket.
2850 Example:
2852 .. parsed-literal::
2854 # launch one QEMU instance
2855 |qemu_system| linux.img \\
2856 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
2857 -netdev socket,id=n1,mcast=230.0.0.1:1234
2858 # launch another QEMU instance on same "bus"
2859 |qemu_system| linux.img \\
2860 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
2861 -netdev socket,id=n2,mcast=230.0.0.1:1234
2862 # launch yet another QEMU instance on same "bus"
2863 |qemu_system| linux.img \\
2864 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\
2865 -netdev socket,id=n3,mcast=230.0.0.1:1234
2867 Example (User Mode Linux compat.):
2869 .. parsed-literal::
2871 # launch QEMU instance (note mcast address selected is UML's default)
2872 |qemu_system| linux.img \\
2873 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
2874 -netdev socket,id=n1,mcast=239.192.168.1:1102
2875 # launch UML
2876 /path/to/linux ubd0=/path/to/root_fs eth0=mcast
2878 Example (send packets from host's 1.2.3.4):
2880 .. parsed-literal::
2882 |qemu_system| linux.img \\
2883 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
2884 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
2886 ``-netdev l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]``
2887 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
2888 is a popular protocol to transport Ethernet (and other Layer 2) data
2889 frames between two systems. It is present in routers, firewalls and
2890 the Linux kernel (from version 3.3 onwards).
2892 This transport allows a VM to communicate to another VM, router or
2893 firewall directly.
2895 ``src=srcaddr``
2896 source address (mandatory)
2898 ``dst=dstaddr``
2899 destination address (mandatory)
2901 ``udp``
2902 select udp encapsulation (default is ip).
2904 ``srcport=srcport``
2905 source udp port.
2907 ``dstport=dstport``
2908 destination udp port.
2910 ``ipv6``
2911 force v6, otherwise defaults to v4.
2913 ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
2914 Cookies are a weak form of security in the l2tpv3 specification.
2915 Their function is mostly to prevent misconfiguration. By default
2916 they are 32 bit.
2918 ``cookie64``
2919 Set cookie size to 64 bit instead of the default 32
2921 ``counter=off``
2922 Force a 'cut-down' L2TPv3 with no counter as in
2923 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
2925 ``pincounter=on``
2926 Work around broken counter handling in peer. This may also help
2927 on networks which have packet reorder.
2929 ``offset=offset``
2930 Add an extra offset between header and data
2932 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to
2933 the bridge br-lan on the remote Linux host 1.2.3.4:
2935 .. parsed-literal::
2937 # Setup tunnel on linux host using raw ip as encapsulation
2938 # on 1.2.3.4
2939 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\
2940 encap udp udp_sport 16384 udp_dport 16384
2941 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\
2942 0xFFFFFFFF peer_session_id 0xFFFFFFFF
2943 ifconfig vmtunnel0 mtu 1500
2944 ifconfig vmtunnel0 up
2945 brctl addif br-lan vmtunnel0
2948 # on 4.3.2.1
2949 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
2951 |qemu_system| linux.img -device e1000,netdev=n1 \\
2952 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
2954 ``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
2955 Configure VDE backend to connect to PORT n of a vde switch running
2956 on host and listening for incoming connections on socketpath. Use
2957 GROUP groupname and MODE octalmode to change default ownership and
2958 permissions for communication port. This option is only available if
2959 QEMU has been compiled with vde support enabled.
2961 Example:
2963 .. parsed-literal::
2965 # launch vde switch
2966 vde_switch -F -sock /tmp/myswitch
2967 # launch QEMU instance
2968 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch
2970 ``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
2971 Establish a vhost-user netdev, backed by a chardev id. The chardev
2972 should be a unix domain socket backed one. The vhost-user uses a
2973 specifically defined protocol to pass vhost ioctl replacement
2974 messages to an application on the other end of the socket. On
2975 non-MSIX guests, the feature can be forced with vhostforce. Use
2976 'queues=n' to specify the number of queues to be created for
2977 multiqueue vhost-user.
2979 Example:
2983 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
2984 -numa node,memdev=mem \
2985 -chardev socket,id=chr0,path=/path/to/socket \
2986 -netdev type=vhost-user,id=net0,chardev=chr0 \
2987 -device virtio-net-pci,netdev=net0
2989 ``-netdev vhost-vdpa,vhostdev=/path/to/dev``
2990 Establish a vhost-vdpa netdev.
2992 vDPA device is a device that uses a datapath which complies with
2993 the virtio specifications with a vendor specific control path.
2994 vDPA devices can be both physically located on the hardware or
2995 emulated by software.
2997 ``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
2998 Create a hub port on the emulated hub with ID hubid.
3000 The hubport netdev lets you connect a NIC to a QEMU emulated hub
3001 instead of a single netdev. Alternatively, you can also connect the
3002 hubport to another netdev with ID nd by using the ``netdev=nd``
3003 option.
3005 ``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
3006 Legacy option to configure or create an on-board (or machine
3007 default) Network Interface Card(NIC) and connect it either to the
3008 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
3009 If model is omitted, then the default NIC model associated with the
3010 machine type is used. Note that the default NIC model may change in
3011 future QEMU releases, so it is highly recommended to always specify
3012 a model. Optionally, the MAC address can be changed to mac, the
3013 device address set to addr (PCI cards only), and a name can be
3014 assigned for use in monitor commands. Optionally, for PCI cards, you
3015 can specify the number v of MSI-X vectors that the card should have;
3016 this option currently only affects virtio cards; set v = 0 to
3017 disable MSI-X. If no ``-net`` option is specified, a single NIC is
3018 created. QEMU can emulate several different models of network card.
3019 Use ``-net nic,model=help`` for a list of available devices for your
3020 target.
3022 ``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
3023 Configure a host network backend (with the options corresponding to
3024 the same ``-netdev`` option) and connect it to the emulated hub 0
3025 (the default hub). Use name to specify the name of the hub port.
3026 ERST
3028 DEFHEADING()
3030 DEFHEADING(Character device options:)
3032 DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
3033 "-chardev help\n"
3034 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3035 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n"
3036 " [,server][,nowait][,telnet][,websocket][,reconnect=seconds][,mux=on|off]\n"
3037 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
3038 "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,websocket][,reconnect=seconds]\n"
3039 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n"
3040 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
3041 " [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n"
3042 " [,logfile=PATH][,logappend=on|off]\n"
3043 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3044 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
3045 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3046 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
3047 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3048 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3049 #ifdef _WIN32
3050 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3051 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3052 #else
3053 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3054 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
3055 #endif
3056 #ifdef CONFIG_BRLAPI
3057 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3058 #endif
3059 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
3060 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
3061 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3062 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3063 #endif
3064 #if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
3065 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3066 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3067 #endif
3068 #if defined(CONFIG_SPICE)
3069 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3070 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3071 #endif
3072 , QEMU_ARCH_ALL
3075 SRST
3076 The general form of a character device option is:
3078 ``-chardev backend,id=id[,mux=on|off][,options]``
3079 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
3080 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
3081 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``,
3082 ``spicevmc``, ``spiceport``. The specific backend will determine the
3083 applicable options.
3085 Use ``-chardev help`` to print all available chardev backend types.
3087 All devices must have an id, which can be any string up to 127
3088 characters long. It is used to uniquely identify this device in
3089 other command line directives.
3091 A character device may be used in multiplexing mode by multiple
3092 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
3093 a "1:N" device, and here the "1" end is your specified chardev
3094 backend, and the "N" end is the various parts of QEMU that can talk
3095 to a chardev. If you create a chardev with ``id=myid`` and
3096 ``mux=on``, QEMU will create a multiplexer with your specified ID,
3097 and you can then configure multiple front ends to use that chardev
3098 ID for their input/output. Up to four different front ends can be
3099 connected to a single multiplexed chardev. (Without multiplexing
3100 enabled, a chardev can only be used by a single front end.) For
3101 instance you could use this to allow a single stdio chardev to be
3102 used by two serial ports and the QEMU monitor:
3106 -chardev stdio,mux=on,id=char0 \
3107 -mon chardev=char0,mode=readline \
3108 -serial chardev:char0 \
3109 -serial chardev:char0
3111 You can have more than one multiplexer in a system configuration;
3112 for instance you could have a TCP port multiplexed between UART 0
3113 and UART 1, and stdio multiplexed between the QEMU monitor and a
3114 parallel port:
3118 -chardev stdio,mux=on,id=char0 \
3119 -mon chardev=char0,mode=readline \
3120 -parallel chardev:char0 \
3121 -chardev tcp,...,mux=on,id=char1 \
3122 -serial chardev:char1 \
3123 -serial chardev:char1
3125 When you're using a multiplexed character device, some escape
3126 sequences are interpreted in the input. See the chapter about
3127 :ref:`keys in the character backend multiplexer` in the
3128 System Emulation Users Guide for more details.
3130 Note that some other command line options may implicitly create
3131 multiplexed character backends; for instance ``-serial mon:stdio``
3132 creates a multiplexed stdio backend connected to the serial port and
3133 the QEMU monitor, and ``-nographic`` also multiplexes the console
3134 and the monitor to stdio.
3136 There is currently no support for multiplexing in the other
3137 direction (where a single QEMU front end takes input and output from
3138 multiple chardevs).
3140 Every backend supports the ``logfile`` option, which supplies the
3141 path to a file to record all data transmitted via the backend. The
3142 ``logappend`` option controls whether the log file will be truncated
3143 or appended to when opened.
3145 The available backends are:
3147 ``-chardev null,id=id``
3148 A void device. This device will not emit any data, and will drop any
3149 data it receives. The null backend does not take any options.
3151 ``-chardev socket,id=id[,TCP options or unix options][,server][,nowait][,telnet][,websocket][,reconnect=seconds][,tls-creds=id][,tls-authz=id]``
3152 Create a two-way stream socket, which can be either a TCP or a unix
3153 socket. A unix socket will be created if ``path`` is specified.
3154 Behaviour is undefined if TCP options are specified for a unix
3155 socket.
3157 ``server`` specifies that the socket shall be a listening socket.
3159 ``nowait`` specifies that QEMU should not block waiting for a client
3160 to connect to a listening socket.
3162 ``telnet`` specifies that traffic on the socket should interpret
3163 telnet escape sequences.
3165 ``websocket`` specifies that the socket uses WebSocket protocol for
3166 communication.
3168 ``reconnect`` sets the timeout for reconnecting on non-server
3169 sockets when the remote end goes away. qemu will delay this many
3170 seconds and then attempt to reconnect. Zero disables reconnecting,
3171 and is the default.
3173 ``tls-creds`` requests enablement of the TLS protocol for
3174 encryption, and specifies the id of the TLS credentials to use for
3175 the handshake. The credentials must be previously created with the
3176 ``-object tls-creds`` argument.
3178 ``tls-auth`` provides the ID of the QAuthZ authorization object
3179 against which the client's x509 distinguished name will be
3180 validated. This object is only resolved at time of use, so can be
3181 deleted and recreated on the fly while the chardev server is active.
3182 If missing, it will default to denying access.
3184 TCP and unix socket options are given below:
3186 ``TCP options: port=port[,host=host][,to=to][,ipv4][,ipv6][,nodelay]``
3187 ``host`` for a listening socket specifies the local address to
3188 be bound. For a connecting socket species the remote host to
3189 connect to. ``host`` is optional for listening sockets. If not
3190 specified it defaults to ``0.0.0.0``.
3192 ``port`` for a listening socket specifies the local port to be
3193 bound. For a connecting socket specifies the port on the remote
3194 host to connect to. ``port`` can be given as either a port
3195 number or a service name. ``port`` is required.
3197 ``to`` is only relevant to listening sockets. If it is
3198 specified, and ``port`` cannot be bound, QEMU will attempt to
3199 bind to subsequent ports up to and including ``to`` until it
3200 succeeds. ``to`` must be specified as a port number.
3202 ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be
3203 used. If neither is specified the socket may use either
3204 protocol.
3206 ``nodelay`` disables the Nagle algorithm.
3208 ``unix options: path=path[,abstract=on|off][,tight=on|off]``
3209 ``path`` specifies the local path of the unix socket. ``path``
3210 is required.
3211 ``abstract`` specifies the use of the abstract socket namespace,
3212 rather than the filesystem. Optional, defaults to false.
3213 ``tight`` sets the socket length of abstract sockets to their minimum,
3214 rather than the full sun_path length. Optional, defaults to true.
3216 ``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4][,ipv6]``
3217 Sends all traffic from the guest to a remote host over UDP.
3219 ``host`` specifies the remote host to connect to. If not specified
3220 it defaults to ``localhost``.
3222 ``port`` specifies the port on the remote host to connect to.
3223 ``port`` is required.
3225 ``localaddr`` specifies the local address to bind to. If not
3226 specified it defaults to ``0.0.0.0``.
3228 ``localport`` specifies the local port to bind to. If not specified
3229 any available local port will be used.
3231 ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be used.
3232 If neither is specified the device may use either protocol.
3234 ``-chardev msmouse,id=id``
3235 Forward QEMU's emulated msmouse events to the guest. ``msmouse``
3236 does not take any options.
3238 ``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
3239 Connect to a QEMU text console. ``vc`` may optionally be given a
3240 specific size.
3242 ``width`` and ``height`` specify the width and height respectively
3243 of the console, in pixels.
3245 ``cols`` and ``rows`` specify that the console be sized to fit a
3246 text console with the given dimensions.
3248 ``-chardev ringbuf,id=id[,size=size]``
3249 Create a ring buffer with fixed size ``size``. size must be a power
3250 of two and defaults to ``64K``.
3252 ``-chardev file,id=id,path=path``
3253 Log all traffic received from the guest to a file.
3255 ``path`` specifies the path of the file to be opened. This file will
3256 be created if it does not already exist, and overwritten if it does.
3257 ``path`` is required.
3259 ``-chardev pipe,id=id,path=path``
3260 Create a two-way connection to the guest. The behaviour differs
3261 slightly between Windows hosts and other hosts:
3263 On Windows, a single duplex pipe will be created at
3264 ``\\.pipe\path``.
3266 On other hosts, 2 pipes will be created called ``path.in`` and
3267 ``path.out``. Data written to ``path.in`` will be received by the
3268 guest. Data written by the guest can be read from ``path.out``. QEMU
3269 will not create these fifos, and requires them to be present.
3271 ``path`` forms part of the pipe path as described above. ``path`` is
3272 required.
3274 ``-chardev console,id=id``
3275 Send traffic from the guest to QEMU's standard output. ``console``
3276 does not take any options.
3278 ``console`` is only available on Windows hosts.
3280 ``-chardev serial,id=id,path=path``
3281 Send traffic from the guest to a serial device on the host.
3283 On Unix hosts serial will actually accept any tty device, not only
3284 serial lines.
3286 ``path`` specifies the name of the serial device to open.
3288 ``-chardev pty,id=id``
3289 Create a new pseudo-terminal on the host and connect to it. ``pty``
3290 does not take any options.
3292 ``pty`` is not available on Windows hosts.
3294 ``-chardev stdio,id=id[,signal=on|off]``
3295 Connect to standard input and standard output of the QEMU process.
3297 ``signal`` controls if signals are enabled on the terminal, that
3298 includes exiting QEMU with the key sequence Control-c. This option
3299 is enabled by default, use ``signal=off`` to disable it.
3301 ``-chardev braille,id=id``
3302 Connect to a local BrlAPI server. ``braille`` does not take any
3303 options.
3305 ``-chardev tty,id=id,path=path``
3306 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD
3307 and DragonFlyBSD hosts. It is an alias for ``serial``.
3309 ``path`` specifies the path to the tty. ``path`` is required.
3311 ``-chardev parallel,id=id,path=path``
3313 ``-chardev parport,id=id,path=path``
3314 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
3315 hosts.
3317 Connect to a local parallel port.
3319 ``path`` specifies the path to the parallel port device. ``path`` is
3320 required.
3322 ``-chardev spicevmc,id=id,debug=debug,name=name``
3323 ``spicevmc`` is only available when spice support is built in.
3325 ``debug`` debug level for spicevmc
3327 ``name`` name of spice channel to connect to
3329 Connect to a spice virtual machine channel, such as vdiport.
3331 ``-chardev spiceport,id=id,debug=debug,name=name``
3332 ``spiceport`` is only available when spice support is built in.
3334 ``debug`` debug level for spicevmc
3336 ``name`` name of spice port to connect to
3338 Connect to a spice port, allowing a Spice client to handle the
3339 traffic identified by a name (preferably a fqdn).
3340 ERST
3342 DEFHEADING()
3344 #ifdef CONFIG_TPM
3345 DEFHEADING(TPM device options:)
3347 DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3348 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3349 " use path to provide path to a character device; default is /dev/tpm0\n"
3350 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
3351 " not provided it will be searched for in /sys/class/misc/tpm?/device\n"
3352 "-tpmdev emulator,id=id,chardev=dev\n"
3353 " configure the TPM device using chardev backend\n",
3354 QEMU_ARCH_ALL)
3355 SRST
3356 The general form of a TPM device option is:
3358 ``-tpmdev backend,id=id[,options]``
3359 The specific backend type will determine the applicable options. The
3360 ``-tpmdev`` option creates the TPM backend and requires a
3361 ``-device`` option that specifies the TPM frontend interface model.
3363 Use ``-tpmdev help`` to print all available TPM backend types.
3365 The available backends are:
3367 ``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
3368 (Linux-host only) Enable access to the host's TPM using the
3369 passthrough driver.
3371 ``path`` specifies the path to the host's TPM device, i.e., on a
3372 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
3373 default ``/dev/tpm0`` is used.
3375 ``cancel-path`` specifies the path to the host TPM device's sysfs
3376 entry allowing for cancellation of an ongoing TPM command.
3377 ``cancel-path`` is optional and by default QEMU will search for the
3378 sysfs entry to use.
3380 Some notes about using the host's TPM with the passthrough driver:
3382 The TPM device accessed by the passthrough driver must not be used
3383 by any other application on the host.
3385 Since the host's firmware (BIOS/UEFI) has already initialized the
3386 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
3387 the TPM again and may therefore not show a TPM-specific menu that
3388 would otherwise allow the user to configure the TPM, e.g., allow the
3389 user to enable/disable or activate/deactivate the TPM. Further, if
3390 TPM ownership is released from within a VM then the host's TPM will
3391 get disabled and deactivated. To enable and activate the TPM again
3392 afterwards, the host has to be rebooted and the user is required to
3393 enter the firmware's menu to enable and activate the TPM. If the TPM
3394 is left disabled and/or deactivated most TPM commands will fail.
3396 To create a passthrough TPM use the following two options:
3400 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3402 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
3403 ``tpmdev=tpm0`` in the device option.
3405 ``-tpmdev emulator,id=id,chardev=dev``
3406 (Linux-host only) Enable access to a TPM emulator using Unix domain
3407 socket based chardev backend.
3409 ``chardev`` specifies the unique ID of a character device backend
3410 that provides connection to the software TPM server.
3412 To create a TPM emulator backend device with chardev socket backend:
3416 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3417 ERST
3419 DEFHEADING()
3421 #endif
3423 DEFHEADING(Linux/Multiboot boot specific:)
3424 SRST
3425 When using these options, you can use a given Linux or Multiboot kernel
3426 without installing it in the disk image. It can be useful for easier
3427 testing of various kernels.
3430 ERST
3432 DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
3433 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
3434 SRST
3435 ``-kernel bzImage``
3436 Use bzImage as kernel image. The kernel can be either a Linux kernel
3437 or in multiboot format.
3438 ERST
3440 DEF("append", HAS_ARG, QEMU_OPTION_append, \
3441 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
3442 SRST
3443 ``-append cmdline``
3444 Use cmdline as kernel command line
3445 ERST
3447 DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
3448 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
3449 SRST
3450 ``-initrd file``
3451 Use file as initial ram disk.
3453 ``-initrd "file1 arg=foo,file2"``
3454 This syntax is only available with multiboot.
3456 Use file1 and file2 as modules and pass arg=foo as parameter to the
3457 first module.
3458 ERST
3460 DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
3461 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL)
3462 SRST
3463 ``-dtb file``
3464 Use file as a device tree binary (dtb) image and pass it to the
3465 kernel on boot.
3466 ERST
3468 DEFHEADING()
3470 DEFHEADING(Debug/Expert options:)
3472 DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
3473 "-fw_cfg [name=]<name>,file=<file>\n"
3474 " add named fw_cfg entry with contents from file\n"
3475 "-fw_cfg [name=]<name>,string=<str>\n"
3476 " add named fw_cfg entry with contents from string\n",
3477 QEMU_ARCH_ALL)
3478 SRST
3479 ``-fw_cfg [name=]name,file=file``
3480 Add named fw\_cfg entry with contents from file file.
3482 ``-fw_cfg [name=]name,string=str``
3483 Add named fw\_cfg entry with contents from string str.
3485 The terminating NUL character of the contents of str will not be
3486 included as part of the fw\_cfg item data. To insert contents with
3487 embedded NUL characters, you have to use the file parameter.
3489 The fw\_cfg entries are passed by QEMU through to the guest.
3491 Example:
3495 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
3497 creates an fw\_cfg entry named opt/com.mycompany/blob with contents
3498 from ./my\_blob.bin.
3499 ERST
3501 DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
3502 "-serial dev redirect the serial port to char device 'dev'\n",
3503 QEMU_ARCH_ALL)
3504 SRST
3505 ``-serial dev``
3506 Redirect the virtual serial port to host character device dev. The
3507 default device is ``vc`` in graphical mode and ``stdio`` in non
3508 graphical mode.
3510 This option can be used several times to simulate up to 4 serial
3511 ports.
3513 Use ``-serial none`` to disable all serial ports.
3515 Available character devices are:
3517 ``vc[:WxH]``
3518 Virtual console. Optionally, a width and height can be given in
3519 pixel with
3523 vc:800x600
3525 It is also possible to specify width or height in characters:
3529 vc:80Cx24C
3531 ``pty``
3532 [Linux only] Pseudo TTY (a new PTY is automatically allocated)
3534 ``none``
3535 No device is allocated.
3537 ``null``
3538 void device
3540 ``chardev:id``
3541 Use a named character device defined with the ``-chardev``
3542 option.
3544 ``/dev/XXX``
3545 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
3546 port parameters are set according to the emulated ones.
3548 ``/dev/parportN``
3549 [Linux only, parallel port only] Use host parallel port N.
3550 Currently SPP and EPP parallel port features can be used.
3552 ``file:filename``
3553 Write output to filename. No character can be read.
3555 ``stdio``
3556 [Unix only] standard input/output
3558 ``pipe:filename``
3559 name pipe filename
3561 ``COMn``
3562 [Windows only] Use host serial port n
3564 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
3565 This implements UDP Net Console. When remote\_host or src\_ip
3566 are not specified they default to ``0.0.0.0``. When not using a
3567 specified src\_port a random port is automatically chosen.
3569 If you just want a simple readonly console you can use
3570 ``netcat`` or ``nc``, by starting QEMU with:
3571 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
3572 QEMU writes something to that port it will appear in the
3573 netconsole session.
3575 If you plan to send characters back via netconsole or you want
3576 to stop and start QEMU a lot of times, you should have QEMU use
3577 the same source port each time by using something like ``-serial
3578 udp::4555@:4556`` to QEMU. Another approach is to use a patched
3579 version of netcat which can listen to a TCP port and send and
3580 receive characters via udp. If you have a patched version of
3581 netcat which activates telnet remote echo and single char
3582 transfer, then you can use the following options to set up a
3583 netcat redirector to allow telnet on port 5555 to access the
3584 QEMU port.
3586 ``QEMU Options:``
3587 -serial udp::4555@:4556
3589 ``netcat options:``
3590 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
3592 ``telnet options:``
3593 localhost 5555
3595 ``tcp:[host]:port[,server][,nowait][,nodelay][,reconnect=seconds]``
3596 The TCP Net Console has two modes of operation. It can send the
3597 serial I/O to a location or wait for a connection from a
3598 location. By default the TCP Net Console is sent to host at the
3599 port. If you use the server option QEMU will wait for a client
3600 socket application to connect to the port before continuing,
3601 unless the ``nowait`` option was specified. The ``nodelay``
3602 option disables the Nagle buffering algorithm. The ``reconnect``
3603 option only applies if noserver is set, if the connection goes
3604 down it will attempt to reconnect at the given interval. If host
3605 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a
3606 time is accepted. You can use ``telnet`` to connect to the
3607 corresponding character device.
3609 ``Example to send tcp console to 192.168.0.2 port 4444``
3610 -serial tcp:192.168.0.2:4444
3612 ``Example to listen and wait on port 4444 for connection``
3613 -serial tcp::4444,server
3615 ``Example to not wait and listen on ip 192.168.0.100 port 4444``
3616 -serial tcp:192.168.0.100:4444,server,nowait
3618 ``telnet:host:port[,server][,nowait][,nodelay]``
3619 The telnet protocol is used instead of raw tcp sockets. The
3620 options work the same as if you had specified ``-serial tcp``.
3621 The difference is that the port acts like a telnet server or
3622 client using telnet option negotiation. This will also allow you
3623 to send the MAGIC\_SYSRQ sequence if you use a telnet that
3624 supports sending the break sequence. Typically in unix telnet
3625 you do it with Control-] and then type "send break" followed by
3626 pressing the enter key.
3628 ``websocket:host:port,server[,nowait][,nodelay]``
3629 The WebSocket protocol is used instead of raw tcp socket. The
3630 port acts as a WebSocket server. Client mode is not supported.
3632 ``unix:path[,server][,nowait][,reconnect=seconds]``
3633 A unix domain socket is used instead of a tcp socket. The option
3634 works the same as if you had specified ``-serial tcp`` except
3635 the unix domain socket path is used for connections.
3637 ``mon:dev_string``
3638 This is a special option to allow the monitor to be multiplexed
3639 onto another serial port. The monitor is accessed with key
3640 sequence of Control-a and then pressing c. dev\_string should be
3641 any one of the serial devices specified above. An example to
3642 multiplex the monitor onto a telnet server listening on port
3643 4444 would be:
3645 ``-serial mon:telnet::4444,server,nowait``
3647 When the monitor is multiplexed to stdio in this way, Ctrl+C
3648 will not terminate QEMU any more but will be passed to the guest
3649 instead.
3651 ``braille``
3652 Braille device. This will use BrlAPI to display the braille
3653 output on a real or fake device.
3655 ``msmouse``
3656 Three button serial mouse. Configure the guest to use Microsoft
3657 protocol.
3658 ERST
3660 DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
3661 "-parallel dev redirect the parallel port to char device 'dev'\n",
3662 QEMU_ARCH_ALL)
3663 SRST
3664 ``-parallel dev``
3665 Redirect the virtual parallel port to host device dev (same devices
3666 as the serial port). On Linux hosts, ``/dev/parportN`` can be used
3667 to use hardware devices connected on the corresponding host parallel
3668 port.
3670 This option can be used several times to simulate up to 3 parallel
3671 ports.
3673 Use ``-parallel none`` to disable all parallel ports.
3674 ERST
3676 DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
3677 "-monitor dev redirect the monitor to char device 'dev'\n",
3678 QEMU_ARCH_ALL)
3679 SRST
3680 ``-monitor dev``
3681 Redirect the monitor to host device dev (same devices as the serial
3682 port). The default device is ``vc`` in graphical mode and ``stdio``
3683 in non graphical mode. Use ``-monitor none`` to disable the default
3684 monitor.
3685 ERST
3686 DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
3687 "-qmp dev like -monitor but opens in 'control' mode\n",
3688 QEMU_ARCH_ALL)
3689 SRST
3690 ``-qmp dev``
3691 Like -monitor but opens in 'control' mode.
3692 ERST
3693 DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
3694 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
3695 QEMU_ARCH_ALL)
3696 SRST
3697 ``-qmp-pretty dev``
3698 Like -qmp but uses pretty JSON formatting.
3699 ERST
3701 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
3702 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
3703 SRST
3704 ``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
3705 Setup monitor on chardev name. ``pretty`` turns on JSON pretty
3706 printing easing human reading and debugging.
3707 ERST
3709 DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
3710 "-debugcon dev redirect the debug console to char device 'dev'\n",
3711 QEMU_ARCH_ALL)
3712 SRST
3713 ``-debugcon dev``
3714 Redirect the debug console to host device dev (same devices as the
3715 serial port). The debug console is an I/O port which is typically
3716 port 0xe9; writing to that I/O port sends output to this device. The
3717 default device is ``vc`` in graphical mode and ``stdio`` in non
3718 graphical mode.
3719 ERST
3721 DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
3722 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL)
3723 SRST
3724 ``-pidfile file``
3725 Store the QEMU process PID in file. It is useful if you launch QEMU
3726 from a script.
3727 ERST
3729 DEF("singlestep", 0, QEMU_OPTION_singlestep, \
3730 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL)
3731 SRST
3732 ``-singlestep``
3733 Run the emulation in single step mode.
3734 ERST
3736 DEF("preconfig", 0, QEMU_OPTION_preconfig, \
3737 "--preconfig pause QEMU before machine is initialized (experimental)\n",
3738 QEMU_ARCH_ALL)
3739 SRST
3740 ``--preconfig``
3741 Pause QEMU for interactive configuration before the machine is
3742 created, which allows querying and configuring properties that will
3743 affect machine initialization. Use QMP command 'x-exit-preconfig' to
3744 exit the preconfig state and move to the next state (i.e. run guest
3745 if -S isn't used or pause the second time if -S is used). This
3746 option is experimental.
3747 ERST
3749 DEF("S", 0, QEMU_OPTION_S, \
3750 "-S freeze CPU at startup (use 'c' to start execution)\n",
3751 QEMU_ARCH_ALL)
3752 SRST
3753 ``-S``
3754 Do not start CPU at startup (you must type 'c' in the monitor).
3755 ERST
3757 DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
3758 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
3759 " run qemu with overcommit hints\n"
3760 " mem-lock=on|off controls memory lock support (default: off)\n"
3761 " cpu-pm=on|off controls cpu power management (default: off)\n",
3762 QEMU_ARCH_ALL)
3763 SRST
3764 ``-overcommit mem-lock=on|off``
3766 ``-overcommit cpu-pm=on|off``
3767 Run qemu with hints about host resource overcommit. The default is
3768 to assume that host overcommits all resources.
3770 Locking qemu and guest memory can be enabled via ``mem-lock=on``
3771 (disabled by default). This works when host memory is not
3772 overcommitted and reduces the worst-case latency for guest.
3774 Guest ability to manage power state of host cpus (increasing latency
3775 for other processes on the same host cpu, but decreasing latency for
3776 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
3777 works best when host CPU is not overcommitted. When used, host
3778 estimates of CPU cycle and power utilization will be incorrect, not
3779 taking into account guest idle time.
3780 ERST
3782 DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
3783 "-gdb dev accept gdb connection on 'dev'. (QEMU defaults to starting\n"
3784 " the guest without waiting for gdb to connect; use -S too\n"
3785 " if you want it to not start execution.)\n",
3786 QEMU_ARCH_ALL)
3787 SRST
3788 ``-gdb dev``
3789 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter
3790 in the System Emulation Users Guide). Note that this option does not pause QEMU
3791 execution -- if you want QEMU to not start the guest until you
3792 connect with gdb and issue a ``continue`` command, you will need to
3793 also pass the ``-S`` option to QEMU.
3795 The most usual configuration is to listen on a local TCP socket::
3797 -gdb tcp::3117
3799 but you can specify other backends; UDP, pseudo TTY, or even stdio
3800 are all reasonable use cases. For example, a stdio connection
3801 allows you to start QEMU from within gdb and establish the
3802 connection via a pipe:
3804 .. parsed-literal::
3806 (gdb) target remote | exec |qemu_system| -gdb stdio ...
3807 ERST
3809 DEF("s", 0, QEMU_OPTION_s, \
3810 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
3811 QEMU_ARCH_ALL)
3812 SRST
3813 ``-s``
3814 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
3815 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide).
3816 ERST
3818 DEF("d", HAS_ARG, QEMU_OPTION_d, \
3819 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n",
3820 QEMU_ARCH_ALL)
3821 SRST
3822 ``-d item1[,...]``
3823 Enable logging of specified items. Use '-d help' for a list of log
3824 items.
3825 ERST
3827 DEF("D", HAS_ARG, QEMU_OPTION_D, \
3828 "-D logfile output log to logfile (default stderr)\n",
3829 QEMU_ARCH_ALL)
3830 SRST
3831 ``-D logfile``
3832 Output log in logfile instead of to stderr
3833 ERST
3835 DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
3836 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
3837 QEMU_ARCH_ALL)
3838 SRST
3839 ``-dfilter range1[,...]``
3840 Filter debug output to that relevant to a range of target addresses.
3841 The filter spec can be either start+size, start-size or start..end
3842 where start end and size are the addresses and sizes required. For
3843 example:
3847 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
3849 Will dump output for any code in the 0x1000 sized block starting at
3850 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
3851 another 0x1000 sized block starting at 0xffffffc00005f000.
3852 ERST
3854 DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
3855 "-seed number seed the pseudo-random number generator\n",
3856 QEMU_ARCH_ALL)
3857 SRST
3858 ``-seed number``
3859 Force the guest to use a deterministic pseudo-random number
3860 generator, seeded with number. This does not affect crypto routines
3861 within the host.
3862 ERST
3864 DEF("L", HAS_ARG, QEMU_OPTION_L, \
3865 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n",
3866 QEMU_ARCH_ALL)
3867 SRST
3868 ``-L path``
3869 Set the directory for the BIOS, VGA BIOS and keymaps.
3871 To list all the data directories, use ``-L help``.
3872 ERST
3874 DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
3875 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL)
3876 SRST
3877 ``-bios file``
3878 Set the filename for the BIOS.
3879 ERST
3881 DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
3882 "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ALL)
3883 SRST
3884 ``-enable-kvm``
3885 Enable KVM full virtualization support. This option is only
3886 available if KVM support is enabled when compiling.
3887 ERST
3889 DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
3890 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL)
3891 DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
3892 "-xen-attach attach to existing xen domain\n"
3893 " libxl will use this when starting QEMU\n",
3894 QEMU_ARCH_ALL)
3895 DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
3896 "-xen-domid-restrict restrict set of available xen operations\n"
3897 " to specified domain id. (Does not affect\n"
3898 " xenpv machine type).\n",
3899 QEMU_ARCH_ALL)
3900 SRST
3901 ``-xen-domid id``
3902 Specify xen guest domain id (XEN only).
3904 ``-xen-attach``
3905 Attach to existing xen domain. libxl will use this when starting
3906 QEMU (XEN only). Restrict set of available xen operations to
3907 specified domain id (XEN only).
3908 ERST
3910 DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
3911 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL)
3912 SRST
3913 ``-no-reboot``
3914 Exit instead of rebooting.
3915 ERST
3917 DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
3918 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL)
3919 SRST
3920 ``-no-shutdown``
3921 Don't exit QEMU on guest shutdown, but instead only stop the
3922 emulation. This allows for instance switching to monitor to commit
3923 changes to the disk image.
3924 ERST
3926 DEF("action", HAS_ARG, QEMU_OPTION_action,
3927 "-action reboot=reset|shutdown\n"
3928 " action when guest reboots [default=reset]\n"
3929 "-action shutdown=poweroff|pause\n"
3930 " action when guest shuts down [default=poweroff]\n"
3931 "-action panic=pause|shutdown|none\n"
3932 " action when guest panics [default=shutdown]\n"
3933 "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
3934 " action when watchdog fires [default=reset]\n",
3935 QEMU_ARCH_ALL)
3936 SRST
3937 ``-action event=action``
3938 The action parameter serves to modify QEMU's default behavior when
3939 certain guest events occur. It provides a generic method for specifying the
3940 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown``
3941 parameters.
3943 Examples:
3945 ``-action panic=none``
3946 ``-action reboot=shutdown,shutdown=pause``
3947 ``-watchdog i6300esb -action watchdog=pause``
3949 ERST
3951 DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
3952 "-loadvm [tag|id]\n" \
3953 " start right away with a saved state (loadvm in monitor)\n",
3954 QEMU_ARCH_ALL)
3955 SRST
3956 ``-loadvm file``
3957 Start right away with a saved state (``loadvm`` in monitor)
3958 ERST
3960 #ifndef _WIN32
3961 DEF("daemonize", 0, QEMU_OPTION_daemonize, \
3962 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
3963 #endif
3964 SRST
3965 ``-daemonize``
3966 Daemonize the QEMU process after initialization. QEMU will not
3967 detach from standard IO until it is ready to receive connections on
3968 any of its devices. This option is a useful way for external
3969 programs to launch QEMU without having to cope with initialization
3970 race conditions.
3971 ERST
3973 DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
3974 "-option-rom rom load a file, rom, into the option ROM space\n",
3975 QEMU_ARCH_ALL)
3976 SRST
3977 ``-option-rom file``
3978 Load the contents of file as an option ROM. This option is useful to
3979 load things like EtherBoot.
3980 ERST
3982 DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
3983 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
3984 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
3985 QEMU_ARCH_ALL)
3987 SRST
3988 ``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
3989 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
3990 the current UTC or local time, respectively. ``localtime`` is
3991 required for correct date in MS-DOS or Windows. To start at a
3992 specific point in time, provide datetime in the format
3993 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.
3995 By default the RTC is driven by the host system time. This allows
3996 using of the RTC as accurate reference clock inside the guest,
3997 specifically if the host time is smoothly following an accurate
3998 external reference clock, e.g. via NTP. If you want to isolate the
3999 guest time from the host, you can set ``clock`` to ``rt`` instead,
4000 which provides a host monotonic clock if host support it. To even
4001 prevent the RTC from progressing during suspension, you can set
4002 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
4003 recommended especially in icount mode in order to preserve
4004 determinism; however, note that in icount mode the speed of the
4005 virtual clock is variable and can in general differ from the host
4006 clock.
4008 Enable ``driftfix`` (i386 targets only) if you experience time drift
4009 problems, specifically with Windows' ACPI HAL. This option will try
4010 to figure out how many timer interrupts were not processed by the
4011 Windows guest and will re-inject them.
4012 ERST
4014 DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
4015 "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \
4016 " enable virtual instruction counter with 2^N clock ticks per\n" \
4017 " instruction, enable aligning the host and virtual clocks\n" \
4018 " or disable real time cpu sleeping, and optionally enable\n" \
4019 " record-and-replay mode\n", QEMU_ARCH_ALL)
4020 SRST
4021 ``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]``
4022 Enable virtual instruction counter. The virtual cpu will execute one
4023 instruction every 2^N ns of virtual time. If ``auto`` is specified
4024 then the virtual cpu speed will be automatically adjusted to keep
4025 virtual time within a few seconds of real time.
4027 Note that while this option can give deterministic behavior, it does
4028 not provide cycle accurate emulation. Modern CPUs contain
4029 superscalar out of order cores with complex cache hierarchies. The
4030 number of instructions executed often has little or no correlation
4031 with actual performance.
4033 When the virtual cpu is sleeping, the virtual time will advance at
4034 default speed unless ``sleep=on`` is specified. With
4035 ``sleep=on``, the virtual time will jump to the next timer
4036 deadline instantly whenever the virtual cpu goes to sleep mode and
4037 will not advance if no timer is enabled. This behavior gives
4038 deterministic execution times from the guest point of view.
4039 The default if icount is enabled is ``sleep=off``.
4040 ``sleep=on`` cannot be used together with either ``shift=auto``
4041 or ``align=on``.
4043 ``align=on`` will activate the delay algorithm which will try to
4044 synchronise the host clock and the virtual clock. The goal is to
4045 have a guest running at the real frequency imposed by the shift
4046 option. Whenever the guest clock is behind the host clock and if
4047 ``align=on`` is specified then we print a message to the user to
4048 inform about the delay. Currently this option does not work when
4049 ``shift`` is ``auto``. Note: The sync algorithm will work for those
4050 shift values for which the guest clock runs ahead of the host clock.
4051 Typically this happens when the shift value is high (how high
4052 depends on the host machine). The default if icount is enabled
4053 is ``align=off``.
4055 When the ``rr`` option is specified deterministic record/replay is
4056 enabled. The ``rrfile=`` option must also be provided to
4057 specify the path to the replay log. In record mode data is written
4058 to this file, and in replay mode it is read back.
4059 If the ``rrsnapshot`` option is given then it specifies a VM snapshot
4060 name. In record mode, a new VM snapshot with the given name is created
4061 at the start of execution recording. In replay mode this option
4062 specifies the snapshot name used to load the initial VM state.
4063 ERST
4065 DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
4066 "-watchdog model\n" \
4067 " enable virtual hardware watchdog [default=none]\n",
4068 QEMU_ARCH_ALL)
4069 SRST
4070 ``-watchdog model``
4071 Create a virtual hardware watchdog device. Once enabled (by a guest
4072 action), the watchdog must be periodically polled by an agent inside
4073 the guest or else the guest will be restarted. Choose a model for
4074 which your guest has drivers.
4076 The model is the model of hardware watchdog to emulate. Use
4077 ``-watchdog help`` to list available hardware models. Only one
4078 watchdog can be enabled for a guest.
4080 The following models may be available:
4082 ``ib700``
4083 iBASE 700 is a very simple ISA watchdog with a single timer.
4085 ``i6300esb``
4086 Intel 6300ESB I/O controller hub is a much more featureful
4087 PCI-based dual-timer watchdog.
4089 ``diag288``
4090 A virtual watchdog for s390x backed by the diagnose 288
4091 hypercall (currently KVM only).
4092 ERST
4094 DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
4095 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
4096 " action when watchdog fires [default=reset]\n",
4097 QEMU_ARCH_ALL)
4098 SRST
4099 ``-watchdog-action action``
4100 The action controls what QEMU will do when the watchdog timer
4101 expires. The default is ``reset`` (forcefully reset the guest).
4102 Other possible actions are: ``shutdown`` (attempt to gracefully
4103 shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
4104 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
4105 guest), ``debug`` (print a debug message and continue), or ``none``
4106 (do nothing).
4108 Note that the ``shutdown`` action requires that the guest responds
4109 to ACPI signals, which it may not be able to do in the sort of
4110 situations where the watchdog would have expired, and thus
4111 ``-watchdog-action shutdown`` is not recommended for production use.
4113 Examples:
4115 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700``
4117 ERST
4119 DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
4120 "-echr chr set terminal escape character instead of ctrl-a\n",
4121 QEMU_ARCH_ALL)
4122 SRST
4123 ``-echr numeric_ascii_value``
4124 Change the escape character used for switching to the monitor when
4125 using monitor and serial sharing. The default is ``0x01`` when using
4126 the ``-nographic`` option. ``0x01`` is equal to pressing
4127 ``Control-a``. You can select a different character from the ascii
4128 control keys where 1 through 26 map to Control-a through Control-z.
4129 For instance you could use the either of the following to change the
4130 escape character to Control-t.
4132 ``-echr 0x14``; \ ``-echr 20``
4134 ERST
4136 DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
4137 "-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]\n" \
4138 "-incoming rdma:host:port[,ipv4][,ipv6]\n" \
4139 "-incoming unix:socketpath\n" \
4140 " prepare for incoming migration, listen on\n" \
4141 " specified protocol and socket address\n" \
4142 "-incoming fd:fd\n" \
4143 "-incoming exec:cmdline\n" \
4144 " accept incoming migration on given file descriptor\n" \
4145 " or from given external command\n" \
4146 "-incoming defer\n" \
4147 " wait for the URI to be specified via migrate_incoming\n",
4148 QEMU_ARCH_ALL)
4149 SRST
4150 ``-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]``
4152 ``-incoming rdma:host:port[,ipv4][,ipv6]``
4153 Prepare for incoming migration, listen on a given tcp port.
4155 ``-incoming unix:socketpath``
4156 Prepare for incoming migration, listen on a given unix socket.
4158 ``-incoming fd:fd``
4159 Accept incoming migration from a given filedescriptor.
4161 ``-incoming exec:cmdline``
4162 Accept incoming migration as an output from specified external
4163 command.
4165 ``-incoming defer``
4166 Wait for the URI to be specified via migrate\_incoming. The monitor
4167 can be used to change settings (such as migration parameters) prior
4168 to issuing the migrate\_incoming to allow the migration to begin.
4169 ERST
4171 DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
4172 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL)
4173 SRST
4174 ``-only-migratable``
4175 Only allow migratable devices. Devices will not be allowed to enter
4176 an unmigratable state.
4177 ERST
4179 DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
4180 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL)
4181 SRST
4182 ``-nodefaults``
4183 Don't create default devices. Normally, QEMU sets the default
4184 devices like serial port, parallel port, virtual console, monitor
4185 device, VGA adapter, floppy and CD-ROM drive and others. The
4186 ``-nodefaults`` option will disable all those default devices.
4187 ERST
4189 #ifndef _WIN32
4190 DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
4191 "-chroot dir chroot to dir just before starting the VM\n",
4192 QEMU_ARCH_ALL)
4193 #endif
4194 SRST
4195 ``-chroot dir``
4196 Immediately before starting guest execution, chroot to the specified
4197 directory. Especially useful in combination with -runas.
4198 ERST
4200 #ifndef _WIN32
4201 DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
4202 "-runas user change to user id user just before starting the VM\n" \
4203 " user can be numeric uid:gid instead\n",
4204 QEMU_ARCH_ALL)
4205 #endif
4206 SRST
4207 ``-runas user``
4208 Immediately before starting guest execution, drop root privileges,
4209 switching to the specified user.
4210 ERST
4212 DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
4213 "-prom-env variable=value\n"
4214 " set OpenBIOS nvram variables\n",
4215 QEMU_ARCH_PPC | QEMU_ARCH_SPARC)
4216 SRST
4217 ``-prom-env variable=value``
4218 Set OpenBIOS nvram variable to given value (PPC, SPARC only).
4222 qemu-system-sparc -prom-env 'auto-boot?=false' \
4223 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
4227 qemu-system-ppc -prom-env 'auto-boot?=false' \
4228 -prom-env 'boot-device=hd:2,\yaboot' \
4229 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
4230 ERST
4231 DEF("semihosting", 0, QEMU_OPTION_semihosting,
4232 "-semihosting semihosting mode\n",
4233 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4234 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV)
4235 SRST
4236 ``-semihosting``
4237 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only).
4239 Note that this allows guest direct access to the host filesystem, so
4240 should only be used with a trusted guest OS.
4242 See the -semihosting-config option documentation for further
4243 information about the facilities this enables.
4244 ERST
4245 DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
4246 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
4247 " semihosting configuration\n",
4248 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4249 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV)
4250 SRST
4251 ``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]``
4252 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V
4253 only).
4255 Note that this allows guest direct access to the host filesystem, so
4256 should only be used with a trusted guest OS.
4258 On Arm this implements the standard semihosting API, version 2.0.
4260 On M68K this implements the "ColdFire GDB" interface used by
4261 libgloss.
4263 Xtensa semihosting provides basic file IO calls, such as
4264 open/read/write/seek/select. Tensilica baremetal libc for ISS and
4265 linux platform "sim" use this interface.
4267 On RISC-V this implements the standard semihosting API, version 0.2.
4269 ``target=native|gdb|auto``
4270 Defines where the semihosting calls will be addressed, to QEMU
4271 (``native``) or to GDB (``gdb``). The default is ``auto``, which
4272 means ``gdb`` during debug sessions and ``native`` otherwise.
4274 ``chardev=str1``
4275 Send the output to a chardev backend output for native or auto
4276 output when not in gdb
4278 ``arg=str1,arg=str2,...``
4279 Allows the user to pass input arguments, and can be used
4280 multiple times to build up a list. The old-style
4281 ``-kernel``/``-append`` method of passing a command line is
4282 still supported for backward compatibility. If both the
4283 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are
4284 specified, the former is passed to semihosting as it always
4285 takes precedence.
4286 ERST
4287 DEF("old-param", 0, QEMU_OPTION_old_param,
4288 "-old-param old param mode\n", QEMU_ARCH_ARM)
4289 SRST
4290 ``-old-param``
4291 Old param mode (ARM only).
4292 ERST
4294 DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
4295 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4296 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4297 " Enable seccomp mode 2 system call filter (default 'off').\n" \
4298 " use 'obsolete' to allow obsolete system calls that are provided\n" \
4299 " by the kernel, but typically no longer used by modern\n" \
4300 " C library implementations.\n" \
4301 " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
4302 " its privileges by blacklisting all set*uid|gid system calls.\n" \
4303 " The value 'children' will deny set*uid|gid system calls for\n" \
4304 " main QEMU process but will allow forks and execves to run unprivileged\n" \
4305 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4306 " blacklisting *fork and execve\n" \
4307 " use 'resourcecontrol' to disable process affinity and schedular priority\n",
4308 QEMU_ARCH_ALL)
4309 SRST
4310 ``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]``
4311 Enable Seccomp mode 2 system call filter. 'on' will enable syscall
4312 filtering and 'off' will disable it. The default is 'off'.
4314 ``obsolete=string``
4315 Enable Obsolete system calls
4317 ``elevateprivileges=string``
4318 Disable set\*uid\|gid system calls
4320 ``spawn=string``
4321 Disable \*fork and execve
4323 ``resourcecontrol=string``
4324 Disable process affinity and schedular priority
4325 ERST
4327 DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
4328 "-readconfig <file>\n", QEMU_ARCH_ALL)
4329 SRST
4330 ``-readconfig file``
4331 Read device configuration from file. This approach is useful when
4332 you want to spawn QEMU process with many command line options but
4333 you don't want to exceed the command line character limit.
4334 ERST
4335 DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
4336 "-writeconfig <file>\n"
4337 " read/write config file\n", QEMU_ARCH_ALL)
4338 SRST
4339 ``-writeconfig file``
4340 Write device configuration to file. The file can be either filename
4341 to save command line and device configuration into file or dash
4342 ``-``) character to print the output to stdout. This can be later
4343 used as input file for ``-readconfig`` option.
4344 ERST
4346 DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4347 "-no-user-config\n"
4348 " do not load default user-provided config files at startup\n",
4349 QEMU_ARCH_ALL)
4350 SRST
4351 ``-no-user-config``
4352 The ``-no-user-config`` option makes QEMU not load any of the
4353 user-provided config files on sysconfdir.
4354 ERST
4356 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4357 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4358 " specify tracing options\n",
4359 QEMU_ARCH_ALL)
4360 SRST
4361 ``-trace [[enable=]pattern][,events=file][,file=file]``
4362 .. include:: ../qemu-option-trace.rst.inc
4364 ERST
4365 DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4366 "-plugin [file=]<file>[,arg=<string>]\n"
4367 " load a plugin\n",
4368 QEMU_ARCH_ALL)
4369 SRST
4370 ``-plugin file=file[,arg=string]``
4371 Load a plugin.
4373 ``file=file``
4374 Load the given plugin from a shared library file.
4376 ``arg=string``
4377 Argument string passed to the plugin. (Can be given multiple
4378 times.)
4379 ERST
4381 HXCOMM Internal use
4382 DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4383 DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4385 #ifdef __linux__
4386 DEF("enable-fips", 0, QEMU_OPTION_enablefips,
4387 "-enable-fips enable FIPS 140-2 compliance\n",
4388 QEMU_ARCH_ALL)
4389 #endif
4390 SRST
4391 ``-enable-fips``
4392 Enable FIPS 140-2 compliance mode.
4393 ERST
4395 DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4396 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
4397 " control error message format\n"
4398 " timestamp=on enables timestamps (default: off)\n"
4399 " guest-name=on enables guest name prefix but only if\n"
4400 " -name guest option is set (default: off)\n",
4401 QEMU_ARCH_ALL)
4402 SRST
4403 ``-msg [timestamp[=on|off]][,guest-name[=on|off]]``
4404 Control error message format.
4406 ``timestamp=on|off``
4407 Prefix messages with a timestamp. Default is off.
4409 ``guest-name=on|off``
4410 Prefix messages with guest name but only if -name guest option is set
4411 otherwise the option is ignored. Default is off.
4412 ERST
4414 DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
4415 "-dump-vmstate <file>\n"
4416 " Output vmstate information in JSON format to file.\n"
4417 " Use the scripts/vmstate-static-checker.py file to\n"
4418 " check for possible regressions in migration code\n"
4419 " by comparing two such vmstate dumps.\n",
4420 QEMU_ARCH_ALL)
4421 SRST
4422 ``-dump-vmstate file``
4423 Dump json-encoded vmstate information for current machine type to
4424 file in file
4425 ERST
4427 DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
4428 "-enable-sync-profile\n"
4429 " enable synchronization profiling\n",
4430 QEMU_ARCH_ALL)
4431 SRST
4432 ``-enable-sync-profile``
4433 Enable synchronization profiling.
4434 ERST
4436 DEFHEADING()
4438 DEFHEADING(Generic object creation:)
4440 DEF("object", HAS_ARG, QEMU_OPTION_object,
4441 "-object TYPENAME[,PROP1=VALUE1,...]\n"
4442 " create a new object of type TYPENAME setting properties\n"
4443 " in the order they are specified. Note that the 'id'\n"
4444 " property must be set. These objects are placed in the\n"
4445 " '/objects' path.\n",
4446 QEMU_ARCH_ALL)
4447 SRST
4448 ``-object typename[,prop1=value1,...]``
4449 Create a new object of type typename setting properties in the order
4450 they are specified. Note that the 'id' property must be set. These
4451 objects are placed in the '/objects' path.
4453 ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,readonly=on|off``
4454 Creates a memory file backend object, which can be used to back
4455 the guest RAM with huge pages.
4457 The ``id`` parameter is a unique ID that will be used to
4458 reference this memory region when configuring the ``-numa``
4459 argument.
4461 The ``size`` option provides the size of the memory region, and
4462 accepts common suffixes, eg ``500M``.
4464 The ``mem-path`` provides the path to either a shared memory or
4465 huge page filesystem mount.
4467 The ``share`` boolean option determines whether the memory
4468 region is marked as private to QEMU, or shared. The latter
4469 allows a co-operating external process to access the QEMU memory
4470 region.
4472 The ``share`` is also required for pvrdma devices due to
4473 limitations in the RDMA API provided by Linux.
4475 Setting share=on might affect the ability to configure NUMA
4476 bindings for the memory backend under some circumstances, see
4477 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
4478 source tree for additional details.
4480 Setting the ``discard-data`` boolean option to on indicates that
4481 file contents can be destroyed when QEMU exits, to avoid
4482 unnecessarily flushing data to the backing file. Note that
4483 ``discard-data`` is only an optimization, and QEMU might not
4484 discard file contents if it aborts unexpectedly or is terminated
4485 using SIGKILL.
4487 The ``merge`` boolean option enables memory merge, also known as
4488 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
4489 the pages for memory deduplication.
4491 Setting the ``dump`` boolean option to off excludes the memory
4492 from core dumps. This feature is also known as MADV\_DONTDUMP.
4494 The ``prealloc`` boolean option enables memory preallocation.
4496 The ``host-nodes`` option binds the memory range to a list of
4497 NUMA host nodes.
4499 The ``policy`` option sets the NUMA policy to one of the
4500 following values:
4502 ``default``
4503 default host policy
4505 ``preferred``
4506 prefer the given host node list for allocation
4508 ``bind``
4509 restrict memory allocation to the given host node list
4511 ``interleave``
4512 interleave memory allocations across the given host node
4513 list
4515 The ``align`` option specifies the base address alignment when
4516 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
4517 ``2M``. Some backend store specified by ``mem-path`` requires an
4518 alignment different than the default one used by QEMU, eg the
4519 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
4520 such cases, users can specify the required alignment via this
4521 option.
4523 The ``pmem`` option specifies whether the backing file specified
4524 by ``mem-path`` is in host persistent memory that can be
4525 accessed using the SNIA NVM programming model (e.g. Intel
4526 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary
4527 operations to guarantee the persistence of its own writes to
4528 ``mem-path`` (e.g. in vNVDIMM label emulation and live
4529 migration). Also, we will map the backend-file with MAP\_SYNC
4530 flag, which ensures the file metadata is in sync for
4531 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
4532 requires support from both the host kernel (since Linux kernel
4533 4.15) and the filesystem of ``mem-path`` mounted with DAX
4534 option.
4536 The ``readonly`` option specifies whether the backing file is opened
4537 read-only or read-write (default).
4539 ``-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``
4540 Creates a memory backend object, which can be used to back the
4541 guest RAM. Memory backend objects offer more control than the
4542 ``-m`` option that is traditionally used to define guest RAM.
4543 Please refer to ``memory-backend-file`` for a description of the
4544 options.
4546 ``-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``
4547 Creates an anonymous memory file backend object, which allows
4548 QEMU to share the memory with an external process (e.g. when
4549 using vhost-user). The memory is allocated with memfd and
4550 optional sealing. (Linux only)
4552 The ``seal`` option creates a sealed-file, that will block
4553 further resizing the memory ('on' by default).
4555 The ``hugetlb`` option specify the file to be created resides in
4556 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
4557 with the ``hugetlb`` option, the ``hugetlbsize`` option specify
4558 the hugetlb page size on systems that support multiple hugetlb
4559 page sizes (it must be a power of 2 value supported by the
4560 system).
4562 In some versions of Linux, the ``hugetlb`` option is
4563 incompatible with the ``seal`` option (requires at least Linux
4564 4.16).
4566 Please refer to ``memory-backend-file`` for a description of the
4567 other options.
4569 The ``share`` boolean option is on by default with memfd.
4571 ``-object rng-builtin,id=id``
4572 Creates a random number generator backend which obtains entropy
4573 from QEMU builtin functions. The ``id`` parameter is a unique ID
4574 that will be used to reference this entropy backend from the
4575 ``virtio-rng`` device. By default, the ``virtio-rng`` device
4576 uses this RNG backend.
4578 ``-object rng-random,id=id,filename=/dev/random``
4579 Creates a random number generator backend which obtains entropy
4580 from a device on the host. The ``id`` parameter is a unique ID
4581 that will be used to reference this entropy backend from the
4582 ``virtio-rng`` device. The ``filename`` parameter specifies
4583 which file to obtain entropy from and if omitted defaults to
4584 ``/dev/urandom``.
4586 ``-object rng-egd,id=id,chardev=chardevid``
4587 Creates a random number generator backend which obtains entropy
4588 from an external daemon running on the host. The ``id``
4589 parameter is a unique ID that will be used to reference this
4590 entropy backend from the ``virtio-rng`` device. The ``chardev``
4591 parameter is the unique ID of a character device backend that
4592 provides the connection to the RNG daemon.
4594 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
4595 Creates a TLS anonymous credentials object, which can be used to
4596 provide TLS support on network backends. The ``id`` parameter is
4597 a unique ID which network backends will use to access the
4598 credentials. The ``endpoint`` is either ``server`` or ``client``
4599 depending on whether the QEMU network backend that uses the
4600 credentials will be acting as a client or as a server. If
4601 ``verify-peer`` is enabled (the default) then once the handshake
4602 is completed, the peer credentials will be verified, though this
4603 is a no-op for anonymous credentials.
4605 The dir parameter tells QEMU where to find the credential files.
4606 For server endpoints, this directory may contain a file
4607 dh-params.pem providing diffie-hellman parameters to use for the
4608 TLS server. If the file is missing, QEMU will generate a set of
4609 DH parameters at startup. This is a computationally expensive
4610 operation that consumes random pool entropy, so it is
4611 recommended that a persistent set of parameters be generated
4612 upfront and saved.
4614 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
4615 Creates a TLS Pre-Shared Keys (PSK) credentials object, which
4616 can be used to provide TLS support on network backends. The
4617 ``id`` parameter is a unique ID which network backends will use
4618 to access the credentials. The ``endpoint`` is either ``server``
4619 or ``client`` depending on whether the QEMU network backend that
4620 uses the credentials will be acting as a client or as a server.
4621 For clients only, ``username`` is the username which will be
4622 sent to the server. If omitted it defaults to "qemu".
4624 The dir parameter tells QEMU where to find the keys file. It is
4625 called "dir/keys.psk" and contains "username:key" pairs. This
4626 file can most easily be created using the GnuTLS ``psktool``
4627 program.
4629 For server endpoints, dir may also contain a file dh-params.pem
4630 providing diffie-hellman parameters to use for the TLS server.
4631 If the file is missing, QEMU will generate a set of DH
4632 parameters at startup. This is a computationally expensive
4633 operation that consumes random pool entropy, so it is
4634 recommended that a persistent set of parameters be generated up
4635 front and saved.
4637 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
4638 Creates a TLS anonymous credentials object, which can be used to
4639 provide TLS support on network backends. The ``id`` parameter is
4640 a unique ID which network backends will use to access the
4641 credentials. The ``endpoint`` is either ``server`` or ``client``
4642 depending on whether the QEMU network backend that uses the
4643 credentials will be acting as a client or as a server. If
4644 ``verify-peer`` is enabled (the default) then once the handshake
4645 is completed, the peer credentials will be verified. With x509
4646 certificates, this implies that the clients must be provided
4647 with valid client certificates too.
4649 The dir parameter tells QEMU where to find the credential files.
4650 For server endpoints, this directory may contain a file
4651 dh-params.pem providing diffie-hellman parameters to use for the
4652 TLS server. If the file is missing, QEMU will generate a set of
4653 DH parameters at startup. This is a computationally expensive
4654 operation that consumes random pool entropy, so it is
4655 recommended that a persistent set of parameters be generated
4656 upfront and saved.
4658 For x509 certificate credentials the directory will contain
4659 further files providing the x509 certificates. The certificates
4660 must be stored in PEM format, in filenames ca-cert.pem,
4661 ca-crl.pem (optional), server-cert.pem (only servers),
4662 server-key.pem (only servers), client-cert.pem (only clients),
4663 and client-key.pem (only clients).
4665 For the server-key.pem and client-key.pem files which contain
4666 sensitive private keys, it is possible to use an encrypted
4667 version by providing the passwordid parameter. This provides the
4668 ID of a previously created ``secret`` object containing the
4669 password for decryption.
4671 The priority parameter allows to override the global default
4672 priority used by gnutls. This can be useful if the system
4673 administrator needs to use a weaker set of crypto priorities for
4674 QEMU without potentially forcing the weakness onto all
4675 applications. Or conversely if one wants wants a stronger
4676 default for QEMU than for all other applications, they can do
4677 this through this parameter. Its format is a gnutls priority
4678 string as described at
4679 https://gnutls.org/manual/html_node/Priority-Strings.html.
4681 ``-object tls-cipher-suites,id=id,priority=priority``
4682 Creates a TLS cipher suites object, which can be used to control
4683 the TLS cipher/protocol algorithms that applications are permitted
4684 to use.
4686 The ``id`` parameter is a unique ID which frontends will use to
4687 access the ordered list of permitted TLS cipher suites from the
4688 host.
4690 The ``priority`` parameter allows to override the global default
4691 priority used by gnutls. This can be useful if the system
4692 administrator needs to use a weaker set of crypto priorities for
4693 QEMU without potentially forcing the weakness onto all
4694 applications. Or conversely if one wants wants a stronger
4695 default for QEMU than for all other applications, they can do
4696 this through this parameter. Its format is a gnutls priority
4697 string as described at
4698 https://gnutls.org/manual/html_node/Priority-Strings.html.
4700 An example of use of this object is to control UEFI HTTPS Boot.
4701 The tls-cipher-suites object exposes the ordered list of permitted
4702 TLS cipher suites from the host side to the guest firmware, via
4703 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER
4704 objects. The firmware uses the IANA_TLS_CIPHER array for configuring
4705 guest-side TLS.
4707 In the following example, the priority at which the host-side policy
4708 is retrieved is given by the ``priority`` property.
4709 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to
4710 refer to /etc/crypto-policies/back-ends/gnutls.config.
4712 .. parsed-literal::
4714 # |qemu_system| \\
4715 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\
4716 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0
4718 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
4719 Interval t can't be 0, this filter batches the packet delivery:
4720 all packets arriving in a given interval on netdev netdevid are
4721 delayed until the end of the interval. Interval is in
4722 microseconds. ``status`` is optional that indicate whether the
4723 netfilter is on (enabled) or off (disabled), the default status
4724 for netfilter will be 'on'.
4726 queue all\|rx\|tx is an option that can be applied to any
4727 netfilter.
4729 ``all``: the filter is attached both to the receive and the
4730 transmit queue of the netdev (default).
4732 ``rx``: the filter is attached to the receive queue of the
4733 netdev, where it will receive packets sent to the netdev.
4735 ``tx``: the filter is attached to the transmit queue of the
4736 netdev, where it will receive packets sent by the netdev.
4738 position head\|tail\|id=<id> is an option to specify where the
4739 filter should be inserted in the filter list. It can be applied
4740 to any netfilter.
4742 ``head``: the filter is inserted at the head of the filter list,
4743 before any existing filters.
4745 ``tail``: the filter is inserted at the tail of the filter list,
4746 behind any existing filters (default).
4748 ``id=<id>``: the filter is inserted before or behind the filter
4749 specified by <id>, see the insert option below.
4751 insert behind\|before is an option to specify where to insert
4752 the new filter relative to the one specified with
4753 position=id=<id>. It can be applied to any netfilter.
4755 ``before``: insert before the specified filter.
4757 ``behind``: insert behind the specified filter (default).
4759 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4760 filter-mirror on netdev netdevid,mirror net packet to
4761 chardevchardevid, if it has the vnet\_hdr\_support flag,
4762 filter-mirror will mirror packet with vnet\_hdr\_len.
4764 ``-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]``
4765 filter-redirector on netdev netdevid,redirect filter's net
4766 packet to chardev chardevid,and redirect indev's packet to
4767 filter.if it has the vnet\_hdr\_support flag, filter-redirector
4768 will redirect packet with vnet\_hdr\_len. Create a
4769 filter-redirector we need to differ outdev id from indev id, id
4770 can not be the same. we can just use indev or outdev, but at
4771 least one of indev or outdev need to be specified.
4773 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4774 Filter-rewriter is a part of COLO project.It will rewrite tcp
4775 packet to secondary from primary to keep secondary tcp
4776 connection,and rewrite tcp packet to primary from secondary make
4777 tcp packet can be handled by client.if it has the
4778 vnet\_hdr\_support flag, we can parse packet with vnet header.
4780 usage: colo secondary: -object
4781 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object
4782 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object
4783 filter-rewriter,id=rew0,netdev=hn0,queue=all
4785 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]``
4786 Dump the network traffic on netdev dev to the file specified by
4787 filename. At most len bytes (64k by default) per packet are
4788 stored. The file format is libpcap, so it can be analyzed with
4789 tools such as tcpdump or Wireshark.
4791 ``-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}]``
4792 Colo-compare gets packet from primary\_in chardevid and
4793 secondary\_in, then compare whether the payload of primary packet
4794 and secondary packet are the same. If same, it will output
4795 primary packet to out\_dev, else it will notify COLO-framework to do
4796 checkpoint and send primary packet to out\_dev. In order to
4797 improve efficiency, we need to put the task of comparison in
4798 another iothread. If it has the vnet\_hdr\_support flag,
4799 colo compare will send/recv packet with vnet\_hdr\_len.
4800 The compare\_timeout=@var{ms} determines the maximum time of the
4801 colo-compare hold the packet. The expired\_scan\_cycle=@var{ms}
4802 is to set the period of scanning expired primary node network packets.
4803 The max\_queue\_size=@var{size} is to set the max compare queue
4804 size depend on user environment.
4805 If user want to use Xen COLO, need to add the notify\_dev to
4806 notify Xen colo-frame to do checkpoint.
4808 COLO-compare must be used with the help of filter-mirror,
4809 filter-redirector and filter-rewriter.
4813 KVM COLO
4815 primary:
4816 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4817 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4818 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4819 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4820 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4821 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4822 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4823 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4824 -object iothread,id=iothread1
4825 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4826 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4827 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4828 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
4830 secondary:
4831 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4832 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4833 -chardev socket,id=red0,host=3.3.3.3,port=9003
4834 -chardev socket,id=red1,host=3.3.3.3,port=9004
4835 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4836 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4839 Xen COLO
4841 primary:
4842 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4843 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4844 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4845 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4846 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4847 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4848 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4849 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4850 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait
4851 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4852 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4853 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4854 -object iothread,id=iothread1
4855 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1
4857 secondary:
4858 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4859 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4860 -chardev socket,id=red0,host=3.3.3.3,port=9003
4861 -chardev socket,id=red1,host=3.3.3.3,port=9004
4862 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4863 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4865 If you want to know the detail of above command line, you can
4866 read the colo-compare git log.
4868 ``-object cryptodev-backend-builtin,id=id[,queues=queues]``
4869 Creates a cryptodev backend which executes crypto opreation from
4870 the QEMU cipher APIS. The id parameter is a unique ID that will
4871 be used to reference this cryptodev backend from the
4872 ``virtio-crypto`` device. The queues parameter is optional,
4873 which specify the queue number of cryptodev backend, the default
4874 of queues is 1.
4876 .. parsed-literal::
4878 # |qemu_system| \\
4879 [...] \\
4880 -object cryptodev-backend-builtin,id=cryptodev0 \\
4881 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
4882 [...]
4884 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]``
4885 Creates a vhost-user cryptodev backend, backed by a chardev
4886 chardevid. The id parameter is a unique ID that will be used to
4887 reference this cryptodev backend from the ``virtio-crypto``
4888 device. The chardev should be a unix domain socket backed one.
4889 The vhost-user uses a specifically defined protocol to pass
4890 vhost ioctl replacement messages to an application on the other
4891 end of the socket. The queues parameter is optional, which
4892 specify the queue number of cryptodev backend for multiqueue
4893 vhost-user, the default of queues is 1.
4895 .. parsed-literal::
4897 # |qemu_system| \\
4898 [...] \\
4899 -chardev socket,id=chardev0,path=/path/to/socket \\
4900 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\
4901 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\
4902 [...]
4904 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]``
4906 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]``
4907 Defines a secret to store a password, encryption key, or some
4908 other sensitive data. The sensitive data can either be passed
4909 directly via the data parameter, or indirectly via the file
4910 parameter. Using the data parameter is insecure unless the
4911 sensitive data is encrypted.
4913 The sensitive data can be provided in raw format (the default),
4914 or base64. When encoded as JSON, the raw format only supports
4915 valid UTF-8 characters, so base64 is recommended for sending
4916 binary data. QEMU will convert from which ever format is
4917 provided to the format it needs internally. eg, an RBD password
4918 can be provided in raw format, even though it will be base64
4919 encoded when passed onto the RBD sever.
4921 For added protection, it is possible to encrypt the data
4922 associated with a secret using the AES-256-CBC cipher. Use of
4923 encryption is indicated by providing the keyid and iv
4924 parameters. The keyid parameter provides the ID of a previously
4925 defined secret that contains the AES-256 decryption key. This
4926 key should be 32-bytes long and be base64 encoded. The iv
4927 parameter provides the random initialization vector used for
4928 encryption of this particular secret and should be a base64
4929 encrypted string of the 16-byte IV.
4931 The simplest (insecure) usage is to provide the secret inline
4933 .. parsed-literal::
4935 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw
4937 The simplest secure usage is to provide the secret via a file
4939 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object
4940 secret,id=sec0,file=mypasswd.txt,format=raw
4942 For greater security, AES-256-CBC should be used. To illustrate
4943 usage, consider the openssl command line tool which can encrypt
4944 the data. Note that when encrypting, the plaintext must be
4945 padded to the cipher block size (32 bytes) using the standard
4946 PKCS#5/6 compatible padding algorithm.
4948 First a master key needs to be created in base64 encoding:
4952 # openssl rand -base64 32 > key.b64
4953 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"')
4955 Each secret to be encrypted needs to have a random
4956 initialization vector generated. These do not need to be kept
4957 secret
4961 # openssl rand -base64 16 > iv.b64
4962 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"')
4964 The secret to be defined can now be encrypted, in this case
4965 we're telling openssl to base64 encode the result, but it could
4966 be left as raw bytes if desired.
4970 # SECRET=$(printf "letmein" |
4971 openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
4973 When launching QEMU, create a master secret pointing to
4974 ``key.b64`` and specify that to be used to decrypt the user
4975 password. Pass the contents of ``iv.b64`` to the second secret
4977 .. parsed-literal::
4979 # |qemu_system| \\
4980 -object secret,id=secmaster0,format=base64,file=key.b64 \\
4981 -object secret,id=sec0,keyid=secmaster0,format=base64,\\
4982 data=$SECRET,iv=$(<iv.b64)
4984 ``-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]``
4985 Create a Secure Encrypted Virtualization (SEV) guest object,
4986 which can be used to provide the guest memory encryption support
4987 on AMD processors.
4989 When memory encryption is enabled, one of the physical address
4990 bit (aka the C-bit) is utilized to mark if a memory page is
4991 protected. The ``cbitpos`` is used to provide the C-bit
4992 position. The C-bit position is Host family dependent hence user
4993 must provide this value. On EPYC, the value should be 47.
4995 When memory encryption is enabled, we loose certain bits in
4996 physical address space. The ``reduced-phys-bits`` is used to
4997 provide the number of bits we loose in physical address space.
4998 Similar to C-bit, the value is Host family dependent. On EPYC,
4999 the value should be 5.
5001 The ``sev-device`` provides the device file to use for
5002 communicating with the SEV firmware running inside AMD Secure
5003 Processor. The default device is '/dev/sev'. If hardware
5004 supports memory encryption then /dev/sev devices are created by
5005 CCP driver.
5007 The ``policy`` provides the guest policy to be enforced by the
5008 SEV firmware and restrict what configuration and operational
5009 commands can be performed on this guest by the hypervisor. The
5010 policy should be provided by the guest owner and is bound to the
5011 guest and cannot be changed throughout the lifetime of the
5012 guest. The default is 0.
5014 If guest ``policy`` allows sharing the key with another SEV
5015 guest then ``handle`` can be use to provide handle of the guest
5016 from which to share the key.
5018 The ``dh-cert-file`` and ``session-file`` provides the guest
5019 owner's Public Diffie-Hillman key defined in SEV spec. The PDH
5020 and session parameters are used for establishing a cryptographic
5021 session with the guest owner to negotiate keys used for
5022 attestation. The file must be encoded in base64.
5024 e.g to launch a SEV guest
5026 .. parsed-literal::
5028 # |qemu_system_x86| \\
5029 ...... \\
5030 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\
5031 -machine ...,memory-encryption=sev0 \\
5032 .....
5034 ``-object authz-simple,id=id,identity=string``
5035 Create an authorization object that will control access to
5036 network services.
5038 The ``identity`` parameter is identifies the user and its format
5039 depends on the network service that authorization object is
5040 associated with. For authorizing based on TLS x509 certificates,
5041 the identity must be the x509 distinguished name. Note that care
5042 must be taken to escape any commas in the distinguished name.
5044 An example authorization object to validate a x509 distinguished
5045 name would look like:
5047 .. parsed-literal::
5049 # |qemu_system| \\
5050 ... \\
5051 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\
5054 Note the use of quotes due to the x509 distinguished name
5055 containing whitespace, and escaping of ','.
5057 ``-object authz-listfile,id=id,filename=path,refresh=on|off``
5058 Create an authorization object that will control access to
5059 network services.
5061 The ``filename`` parameter is the fully qualified path to a file
5062 containing the access control list rules in JSON format.
5064 An example set of rules that match against SASL usernames might
5065 look like:
5070 "rules": [
5071 { "match": "fred", "policy": "allow", "format": "exact" },
5072 { "match": "bob", "policy": "allow", "format": "exact" },
5073 { "match": "danb", "policy": "deny", "format": "glob" },
5074 { "match": "dan*", "policy": "allow", "format": "exact" },
5076 "policy": "deny"
5079 When checking access the object will iterate over all the rules
5080 and the first rule to match will have its ``policy`` value
5081 returned as the result. If no rules match, then the default
5082 ``policy`` value is returned.
5084 The rules can either be an exact string match, or they can use
5085 the simple UNIX glob pattern matching to allow wildcards to be
5086 used.
5088 If ``refresh`` is set to true the file will be monitored and
5089 automatically reloaded whenever its content changes.
5091 As with the ``authz-simple`` object, the format of the identity
5092 strings being matched depends on the network service, but is
5093 usually a TLS x509 distinguished name, or a SASL username.
5095 An example authorization object to validate a SASL username
5096 would look like:
5098 .. parsed-literal::
5100 # |qemu_system| \\
5101 ... \\
5102 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\
5105 ``-object authz-pam,id=id,service=string``
5106 Create an authorization object that will control access to
5107 network services.
5109 The ``service`` parameter provides the name of a PAM service to
5110 use for authorization. It requires that a file
5111 ``/etc/pam.d/service`` exist to provide the configuration for
5112 the ``account`` subsystem.
5114 An example authorization object to validate a TLS x509
5115 distinguished name would look like:
5117 .. parsed-literal::
5119 # |qemu_system| \\
5120 ... \\
5121 -object authz-pam,id=auth0,service=qemu-vnc \\
5124 There would then be a corresponding config file for PAM at
5125 ``/etc/pam.d/qemu-vnc`` that contains:
5129 account requisite pam_listfile.so item=user sense=allow \
5130 file=/etc/qemu/vnc.allow
5132 Finally the ``/etc/qemu/vnc.allow`` file would contain the list
5133 of x509 distingished names that are permitted access
5137 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
5139 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink``
5140 Creates a dedicated event loop thread that devices can be
5141 assigned to. This is known as an IOThread. By default device
5142 emulation happens in vCPU threads or the main event loop thread.
5143 This can become a scalability bottleneck. IOThreads allow device
5144 emulation and I/O to run on other host CPUs.
5146 The ``id`` parameter is a unique ID that will be used to
5147 reference this IOThread from ``-device ...,iothread=id``.
5148 Multiple devices can be assigned to an IOThread. Note that not
5149 all devices support an ``iothread`` parameter.
5151 The ``query-iothreads`` QMP command lists IOThreads and reports
5152 their thread IDs so that the user can configure host CPU
5153 pinning/affinity.
5155 IOThreads use an adaptive polling algorithm to reduce event loop
5156 latency. Instead of entering a blocking system call to monitor
5157 file descriptors and then pay the cost of being woken up when an
5158 event occurs, the polling algorithm spins waiting for events for
5159 a short time. The algorithm's default parameters are suitable
5160 for many cases but can be adjusted based on knowledge of the
5161 workload and/or host device latency.
5163 The ``poll-max-ns`` parameter is the maximum number of
5164 nanoseconds to busy wait for events. Polling can be disabled by
5165 setting this value to 0.
5167 The ``poll-grow`` parameter is the multiplier used to increase
5168 the polling time when the algorithm detects it is missing events
5169 due to not polling long enough.
5171 The ``poll-shrink`` parameter is the divisor used to decrease
5172 the polling time when the algorithm detects it is spending too
5173 long polling without encountering events.
5175 The polling parameters can be modified at run-time using the
5176 ``qom-set`` command (where ``iothread1`` is the IOThread's
5177 ``id``):
5181 (qemu) qom-set /objects/iothread1 poll-max-ns 100000
5182 ERST
5185 HXCOMM This is the last statement. Insert new options before this line!