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
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)
18 DEF("version", 0, QEMU_OPTION_version,
19 "-version display version information and exit\n", QEMU_ARCH_ALL)
22 Display version information and exit
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 " enforce-config-section=on|off enforce configuration section migration (default=off)\n"
38 " memory-encryption=@var{} memory encryption object to use (default=none)\n"
39 " hmat=on|off controls ACPI HMAT support (default=off)\n",
42 ``-machine [type=]name[,prop=value[,...]]``
43 Select the emulated machine by name. Use ``-machine help`` to list
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
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.
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
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
92 Enables or disables NVDIMM support. The default is off.
94 ``enforce-config-section=on|off``
95 If ``enforce-config-section`` is set to on, force migration code
96 to send configuration section even if the machine-type sets the
97 ``migration.send-configuration`` property to off. NOTE: this
98 parameter is deprecated. Please use ``-global``
99 ``migration.send-configuration``\ =on\|off instead.
101 ``memory-encryption=``
102 Memory encryption object to use. The default is none.
105 Enables or disables ACPI Heterogeneous Memory Attribute Table
106 (HMAT) support. The default is off.
109 HXCOMM Deprecated by -machine
110 DEF("M", HAS_ARG, QEMU_OPTION_M, "", QEMU_ARCH_ALL)
112 DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
113 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
116 Select CPU model (``-cpu help`` for list and additional feature
120 DEF("accel", HAS_ARG, QEMU_OPTION_accel,
121 "-accel [accel=]accelerator[,prop[=value][,...]]\n"
122 " select accelerator (kvm, xen, hax, hvf, whpx or tcg; use 'help' for a list)\n"
123 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
124 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
125 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
126 " tb-size=n (TCG translation block cache size)\n"
127 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
129 ``-accel name[,prop=value[,...]]``
130 This is used to enable an accelerator. Depending on the target
131 architecture, kvm, xen, hax, hvf, whpx or tcg can be available. By
132 default, tcg is used. If there is more than one accelerator
133 specified, the next one is used if the previous one fails to
136 ``igd-passthru=on|off``
137 When Xen is in use, this option controls whether Intel
138 integrated graphics devices can be passed through to the guest
141 ``kernel-irqchip=on|off|split``
142 Controls KVM in-kernel irqchip support. The default is full
143 acceleration of the interrupt controllers. On x86, split irqchip
144 reduces the kernel attack surface, at a performance cost for
145 non-MSI interrupts. Disabling the in-kernel irqchip completely
146 is not recommended except for debugging purposes.
148 ``kvm-shadow-mem=size``
149 Defines the size of the KVM shadow MMU.
152 Controls the size (in MiB) of the TCG translation block cache.
154 ``thread=single|multi``
155 Controls number of TCG threads. When the TCG is multi-threaded
156 there will be one thread per vCPU therefor taking advantage of
157 additional host cores. The default is to enable multi-threading
158 where both the back-end and front-ends support it and no
159 incompatible TCG features have been enabled (e.g.
163 DEF("smp", HAS_ARG, QEMU_OPTION_smp,
164 "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n"
165 " set the number of CPUs to 'n' [default=1]\n"
166 " maxcpus= maximum number of total cpus, including\n"
167 " offline CPUs for hotplug, etc\n"
168 " cores= number of CPU cores on one socket (for PC, it's on one die)\n"
169 " threads= number of threads on one CPU core\n"
170 " dies= number of CPU dies on one socket (for PC only)\n"
171 " sockets= number of discrete sockets in the system\n",
174 ``-smp [cpus=]n[,cores=cores][,threads=threads][,dies=dies][,sockets=sockets][,maxcpus=maxcpus]``
175 Simulate an SMP system with n CPUs. On the PC target, up to 255 CPUs
176 are supported. On Sparc32 target, Linux limits the number of usable
177 CPUs to 4. For the PC target, the number of cores per die, the
178 number of threads per cores, the number of dies per packages and the
179 total number of sockets can be specified. Missing values will be
180 computed. If any on the three values is given, the total number of
181 CPUs n can be omitted. maxcpus specifies the maximum number of
185 DEF("numa", HAS_ARG, QEMU_OPTION_numa,
186 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
187 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
188 "-numa dist,src=source,dst=destination,val=distance\n"
189 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
190 "-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"
191 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
194 ``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
196 ``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]``
198 ``-numa dist,src=source,dst=destination,val=distance``
200 ``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]``
202 ``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]``
204 ``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]``
205 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA
206 distance from a source node to a destination node. Set the ACPI
207 Heterogeneous Memory Attributes for the given nodes.
209 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and
210 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a
211 contiguous range of CPU indexes (or a single VCPU if lastcpu is
212 omitted). A non-contiguous set of VCPUs can be represented by
213 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is
214 omitted on all nodes, VCPUs are automatically split between them.
216 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a
221 -numa node,cpus=0-2,cpus=5
223 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option
224 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to
225 assign CPU objects to a node using topology layout properties of
226 CPU. The set of properties is machine specific, and depends on used
227 machine type/'\ ``smp``\ ' options. It could be queried with
228 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ '
229 property specifies node to which CPU object will be assigned, it's
230 required for node to be declared with '\ ``node``\ ' option before
231 it's used with '\ ``cpu``\ ' option.
238 -smp 1,sockets=2,maxcpus=2 \
239 -numa node,nodeid=0 -numa node,nodeid=1 \
240 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
242 '\ ``mem``\ ' assigns a given RAM amount to a node. '\ ``memdev``\ '
243 assigns RAM from a given memory backend device to a node. If
244 '\ ``mem``\ ' and '\ ``memdev``\ ' are omitted in all nodes, RAM is
245 split equally between them.
247 '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive.
248 Furthermore, if one node uses '\ ``memdev``\ ', all of them have to
251 '\ ``initiator``\ ' is an additional option that points to an
252 initiator NUMA node that has best performance (the lowest latency or
253 largest bandwidth) to this NUMA node. Note that this option can be
254 set only when the machine property 'hmat' is set to 'on'.
256 Following example creates a machine with 2 NUMA nodes, node 0 has
257 CPU. node 1 has only memory, and its initiator is node 0. Note that
258 because node 0 has CPU, by default the initiator of node 0 is itself
264 -m 2G,slots=2,maxmem=4G \
265 -object memory-backend-ram,size=1G,id=m0 \
266 -object memory-backend-ram,size=1G,id=m1 \
267 -numa node,nodeid=0,memdev=m0 \
268 -numa node,nodeid=1,memdev=m1,initiator=0 \
269 -smp 2,sockets=2,maxcpus=2 \
270 -numa cpu,node-id=0,socket-id=0 \
271 -numa cpu,node-id=0,socket-id=1
273 source and destination are NUMA node IDs. distance is the NUMA
274 distance from source to destination. The distance from a node to
275 itself is always 10. If any pair of nodes is given a distance, then
276 all pairs must be given distances. Although, when distances are only
277 given in one direction for each pair of nodes, then the distances in
278 the opposite directions are assumed to be the same. If, however, an
279 asymmetrical pair of distances is given for even one node pair, then
280 all node pairs must be provided distance values for both directions,
281 even when they are symmetrical. When a node is unreachable from
282 another node, set the pair's distance to 255.
284 Note that the -``numa`` option doesn't allocate any of the specified
285 resources, it just assigns existing resources to NUMA nodes. This
286 means that one still has to use the ``-m``, ``-smp`` options to
287 allocate RAM and VCPUs respectively.
289 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
290 Information between initiator and target NUMA nodes in ACPI
291 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can
292 create memory requests, usually it has one or more processors.
293 Target NUMA node contains addressable memory.
295 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is
296 the memory hierarchy of the target NUMA node: if hierarchy is
297 'memory', the structure represents the memory performance; if
298 hierarchy is 'first-level\|second-level\|third-level', this
299 structure represents aggregated performance of memory side caches
300 for each domain. type of 'data-type' is type of data represented by
301 this structure instance: if 'hierarchy' is 'memory', 'data-type' is
302 'access\|read\|write' latency or 'access\|read\|write' bandwidth of
303 the target memory; if 'hierarchy' is
304 'first-level\|second-level\|third-level', 'data-type' is
305 'access\|read\|write' hit latency or 'access\|read\|write' hit
306 bandwidth of the target memory side cache.
308 lat is latency value in nanoseconds. bw is bandwidth value, the
309 possible value and units are NUM[M\|G\|T], mean that the bandwidth
310 value are NUM byte per second (or MB/s, GB/s or TB/s depending on
311 used suffix). Note that if latency or bandwidth value is 0, means
312 the corresponding latency or bandwidth information is not provided.
314 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory
315 belongs. size is the size of memory side cache in bytes. level is
316 the cache level described in this structure, note that the cache
317 level 0 should not be used with '\ ``hmat-cache``\ ' option.
318 associativity is the cache associativity, the possible value is
319 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
320 is the write policy. line is the cache Line size in bytes.
322 For example, the following options describe 2 NUMA nodes. Node 0 has
323 2 cpus and a ram, node 1 has only a ram. The processors in node 0
324 access memory in node 0 with access-latency 5 nanoseconds,
325 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access
326 memory in NUMA node 1 with access-latency 10 nanoseconds,
327 access-bandwidth is 100 MB/s. And for memory side cache information,
328 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB,
329 policy is write-back, the cache Line size is 8 bytes:
335 -object memory-backend-ram,size=1G,id=m0 \
336 -object memory-backend-ram,size=1G,id=m1 \
338 -numa node,nodeid=0,memdev=m0 \
339 -numa node,nodeid=1,memdev=m1,initiator=0 \
340 -numa cpu,node-id=0,socket-id=0 \
341 -numa cpu,node-id=0,socket-id=1 \
342 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \
343 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \
344 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
345 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \
346 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \
347 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
350 DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
351 "-add-fd fd=fd,set=set[,opaque=opaque]\n"
352 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
354 ``-add-fd fd=fd,set=set[,opaque=opaque]``
355 Add a file descriptor to an fd set. Valid options are:
358 This option defines the file descriptor of which a duplicate is
359 added to fd set. The file descriptor cannot be stdin, stdout, or
363 This option defines the ID of the fd set to add the file
367 This option defines a free-form string that can be used to
370 You can open an image using pre-opened file descriptors from an fd
376 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
377 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
378 -drive file=/dev/fdset/2,index=0,media=disk
381 DEF("set", HAS_ARG, QEMU_OPTION_set,
382 "-set group.id.arg=value\n"
383 " set <arg> parameter for item <id> of type <group>\n"
384 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
386 ``-set group.id.arg=value``
387 Set parameter arg for item id of type group
390 DEF("global", HAS_ARG, QEMU_OPTION_global,
391 "-global driver.property=value\n"
392 "-global driver=driver,property=property,value=value\n"
393 " set a global default for a driver property\n",
396 ``-global driver.prop=value``
398 ``-global driver=driver,property=property,value=value``
399 Set default value of driver's property prop to value, e.g.:
403 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img
405 In particular, you can use this to set driver properties for devices
406 which are created automatically by the machine model. To create a
407 device which is not created automatically and set properties on it,
410 -global driver.prop=value is shorthand for -global
411 driver=driver,property=prop,value=value. The longhand syntax works
412 even when driver contains a dot.
415 DEF("boot", HAS_ARG, QEMU_OPTION_boot,
416 "-boot [order=drives][,once=drives][,menu=on|off]\n"
417 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
418 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
419 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
420 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n"
421 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
424 ``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
425 Specify boot order drives as a string of drive letters. Valid drive
426 letters depend on the target architecture. The x86 PC uses: a, b
427 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
428 (Etherboot from network adapter 1-4), hard disk boot is the default.
429 To apply a particular boot order only on the first startup, specify
430 it via ``once``. Note that the ``order`` or ``once`` parameter
431 should not be used together with the ``bootindex`` property of
432 devices, since the firmware implementations normally do not support
433 both at the same time.
435 Interactive boot menus/prompts can be enabled via ``menu=on`` as far
436 as firmware/BIOS supports them. The default is non-interactive boot.
438 A splash picture could be passed to bios, enabling user to show it
439 as logo, when option splash=sp\_name is given and menu=on, If
440 firmware/BIOS supports them. Currently Seabios for X86 system
441 support it. limitation: The splash file could be a jpeg file or a
442 BMP file in 24 BPP format(true color). The resolution should be
443 supported by the SVGA mode, so the recommended is 320x240, 640x480,
446 A timeout could be passed to bios, guest will pause for rb\_timeout
447 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
448 not reboot, qemu passes '-1' to bios by default. Currently Seabios
449 for X86 system support it.
451 Do strict boot via ``strict=on`` as far as firmware/BIOS supports
452 it. This only effects when boot priority is changed by bootindex
453 options. The default is non-strict boot.
457 # try to boot from network first, then from hard disk
458 |qemu_system_x86| -boot order=nc
459 # boot from CD-ROM first, switch back to default order after reboot
460 |qemu_system_x86| -boot once=d
461 # boot with a splash picture for 5 seconds.
462 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000
464 Note: The legacy format '-boot drives' is still supported but its
465 use is discouraged as it may be removed from future versions.
468 DEF("m", HAS_ARG, QEMU_OPTION_m,
469 "-m [size=]megs[,slots=n,maxmem=size]\n"
470 " configure guest RAM\n"
471 " size: initial amount of guest memory\n"
472 " slots: number of hotplug slots (default: none)\n"
473 " maxmem: maximum amount of guest memory (default: none)\n"
474 "NOTE: Some architectures might enforce a specific granularity\n",
477 ``-m [size=]megs[,slots=n,maxmem=size]``
478 Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
479 Optionally, a suffix of "M" or "G" can be used to signify a value in
480 megabytes or gigabytes respectively. Optional pair slots, maxmem
481 could be used to set amount of hotpluggable memory slots and maximum
482 amount of memory. Note that maxmem must be aligned to the page size.
484 For example, the following command-line sets the guest startup RAM
485 size to 1GB, creates 3 slots to hotplug additional memory and sets
486 the maximum memory the guest can reach to 4GB:
490 |qemu_system| -m 1G,slots=3,maxmem=4G
492 If slots and maxmem are not specified, memory hotplug won't be
493 enabled and the guest startup RAM will never increase.
496 DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
497 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
500 Allocate guest RAM from a temporarily created file in path.
503 DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
504 "-mem-prealloc preallocate guest memory (use with -mem-path)\n",
508 Preallocate memory when using -mem-path.
511 DEF("k", HAS_ARG, QEMU_OPTION_k,
512 "-k language use keyboard layout (for example 'fr' for French)\n",
516 Use keyboard layout language (for example ``fr`` for French). This
517 option is only needed where it is not easy to get raw PC keycodes
518 (e.g. on Macs, with some X11 servers or with a VNC or curses
519 display). You don't normally need to use it on PC/Linux or
522 The available layouts are:
526 ar de-ch es fo fr-ca hu ja mk no pt-br sv
527 da en-gb et fr fr-ch is lt nl pl ru th
528 de en-us fi fr-be hr it lv nl-be pt sl tr
530 The default is ``en-us``.
534 HXCOMM Deprecated by -audiodev
535 DEF("audio-help", 0, QEMU_OPTION_audio_help,
536 "-audio-help show -audiodev equivalent of the currently specified audio settings\n",
540 Will show the -audiodev equivalent of the currently specified
541 (deprecated) environment variables.
544 DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
545 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
546 " specifies the audio backend to use\n"
547 " id= identifier of the backend\n"
548 " timer-period= timer period in microseconds\n"
549 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
550 " in|out.fixed-settings= use fixed settings for host audio\n"
551 " in|out.frequency= frequency to use with fixed settings\n"
552 " in|out.channels= number of channels to use with fixed settings\n"
553 " in|out.format= sample format to use with fixed settings\n"
554 " valid values: s8, s16, s32, u8, u16, u32, f32\n"
555 " in|out.voices= number of voices to use\n"
556 " in|out.buffer-length= length of buffer in microseconds\n"
557 "-audiodev none,id=id,[,prop[=value][,...]]\n"
558 " dummy driver that discards all output\n"
559 #ifdef CONFIG_AUDIO_ALSA
560 "-audiodev alsa,id=id[,prop[=value][,...]]\n"
561 " in|out.dev= name of the audio device to use\n"
562 " in|out.period-length= length of period in microseconds\n"
563 " in|out.try-poll= attempt to use poll mode\n"
564 " threshold= threshold (in microseconds) when playback starts\n"
566 #ifdef CONFIG_AUDIO_COREAUDIO
567 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
568 " in|out.buffer-count= number of buffers\n"
570 #ifdef CONFIG_AUDIO_DSOUND
571 "-audiodev dsound,id=id[,prop[=value][,...]]\n"
572 " latency= add extra latency to playback in microseconds\n"
574 #ifdef CONFIG_AUDIO_OSS
575 "-audiodev oss,id=id[,prop[=value][,...]]\n"
576 " in|out.dev= path of the audio device to use\n"
577 " in|out.buffer-count= number of buffers\n"
578 " in|out.try-poll= attempt to use poll mode\n"
579 " try-mmap= try using memory mapped access\n"
580 " exclusive= open device in exclusive mode\n"
581 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
583 #ifdef CONFIG_AUDIO_PA
584 "-audiodev pa,id=id[,prop[=value][,...]]\n"
585 " server= PulseAudio server address\n"
586 " in|out.name= source/sink device name\n"
587 " in|out.latency= desired latency in microseconds\n"
589 #ifdef CONFIG_AUDIO_SDL
590 "-audiodev sdl,id=id[,prop[=value][,...]]\n"
593 "-audiodev spice,id=id[,prop[=value][,...]]\n"
595 "-audiodev wav,id=id[,prop[=value][,...]]\n"
596 " path= path of wav file to record\n",
599 ``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
600 Adds a new audio backend driver identified by id. There are global
601 and driver specific properties. Some values can be set differently
602 for input and output, they're marked with ``in|out.``. You can set
603 the input's property with ``in.prop`` and the output's property with
604 ``out.prop``. For example:
608 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
609 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
611 NOTE: parameter validation is known to be incomplete, in many cases
612 specifying an invalid option causes QEMU to print an error message
613 and continue emulation without sound.
615 Valid global options are:
618 Identifies the audio backend.
620 ``timer-period=period``
621 Sets the timer period used by the audio subsystem in
622 microseconds. Default is 10000 (10 ms).
624 ``in|out.mixing-engine=on|off``
625 Use QEMU's mixing engine to mix all streams inside QEMU and
626 convert audio formats when not supported by the backend. When
627 off, fixed-settings must be off too. Note that disabling this
628 option means that the selected backend must support multiple
629 streams and the audio formats used by the virtual cards,
630 otherwise you'll get no sound. It's not recommended to disable
631 this option unless you want to use 5.1 or 7.1 audio, as mixing
632 engine only supports mono and stereo audio. Default is on.
634 ``in|out.fixed-settings=on|off``
635 Use fixed settings for host audio. When off, it will change
636 based on how the guest opens the sound card. In this case you
637 must not specify frequency, channels or format. Default is on.
639 ``in|out.frequency=frequency``
640 Specify the frequency to use when using fixed-settings. Default
643 ``in|out.channels=channels``
644 Specify the number of channels to use when using fixed-settings.
645 Default is 2 (stereo).
647 ``in|out.format=format``
648 Specify the sample format to use when using fixed-settings.
649 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
650 ``u32``, ``f32``. Default is ``s16``.
652 ``in|out.voices=voices``
653 Specify the number of voices to use. Default is 1.
655 ``in|out.buffer-length=usecs``
656 Sets the size of the buffer in microseconds.
658 ``-audiodev none,id=id[,prop[=value][,...]]``
659 Creates a dummy backend that discards all outputs. This backend has
660 no backend specific properties.
662 ``-audiodev alsa,id=id[,prop[=value][,...]]``
663 Creates backend using the ALSA. This backend is only available on
666 ALSA specific options are:
668 ``in|out.dev=device``
669 Specify the ALSA device to use for input and/or output. Default
672 ``in|out.period-length=usecs``
673 Sets the period length in microseconds.
675 ``in|out.try-poll=on|off``
676 Attempt to use poll mode with the device. Default is on.
678 ``threshold=threshold``
679 Threshold (in microseconds) when playback starts. Default is 0.
681 ``-audiodev coreaudio,id=id[,prop[=value][,...]]``
682 Creates a backend using Apple's Core Audio. This backend is only
683 available on Mac OS and only supports playback.
685 Core Audio specific options are:
687 ``in|out.buffer-count=count``
688 Sets the count of the buffers.
690 ``-audiodev dsound,id=id[,prop[=value][,...]]``
691 Creates a backend using Microsoft's DirectSound. This backend is
692 only available on Windows and only supports playback.
694 DirectSound specific options are:
697 Add extra usecs microseconds latency to playback. Default is
700 ``-audiodev oss,id=id[,prop[=value][,...]]``
701 Creates a backend using OSS. This backend is available on most
704 OSS specific options are:
706 ``in|out.dev=device``
707 Specify the file name of the OSS device to use. Default is
710 ``in|out.buffer-count=count``
711 Sets the count of the buffers.
713 ``in|out.try-poll=on|of``
714 Attempt to use poll mode with the device. Default is on.
717 Try using memory mapped device access. Default is off.
720 Open the device in exclusive mode (vmix won't work in this
721 case). Default is off.
723 ``dsp-policy=policy``
724 Sets the timing policy (between 0 and 10, where smaller number
725 means smaller latency but higher CPU usage). Use -1 to use
726 buffer sizes specified by ``buffer`` and ``buffer-count``. This
727 option is ignored if you do not have OSS 4. Default is 5.
729 ``-audiodev pa,id=id[,prop[=value][,...]]``
730 Creates a backend using PulseAudio. This backend is available on
733 PulseAudio specific options are:
736 Sets the PulseAudio server to connect to.
739 Use the specified source/sink for recording/playback.
741 ``in|out.latency=usecs``
742 Desired latency in microseconds. The PulseAudio server will try
743 to honor this value but actual latencies may be lower or higher.
745 ``-audiodev sdl,id=id[,prop[=value][,...]]``
746 Creates a backend using SDL. This backend is available on most
747 systems, but you should use your platform's native backend if
748 possible. This backend has no backend specific properties.
750 ``-audiodev spice,id=id[,prop[=value][,...]]``
751 Creates a backend that sends audio through SPICE. This backend
752 requires ``-spice`` and automatically selected in that case, so
753 usually you can ignore this option. This backend has no backend
756 ``-audiodev wav,id=id[,prop[=value][,...]]``
757 Creates a backend that writes audio to a WAV file.
759 Backend specific options are:
762 Write recorded audio into the specified file. Default is
766 DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
767 "-soundhw c1,... enable audio support\n"
768 " and only specified sound cards (comma separated list)\n"
769 " use '-soundhw help' to get the list of supported cards\n"
770 " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
772 ``-soundhw card1[,card2,...] or -soundhw all``
773 Enable audio and selected sound hardware. Use 'help' to print all
774 available sound hardware. For example:
778 |qemu_system_x86| -soundhw sb16,adlib disk.img
779 |qemu_system_x86| -soundhw es1370 disk.img
780 |qemu_system_x86| -soundhw ac97 disk.img
781 |qemu_system_x86| -soundhw hda disk.img
782 |qemu_system_x86| -soundhw all disk.img
783 |qemu_system_x86| -soundhw help
785 Note that Linux's i810\_audio OSS kernel (for AC97) module might
786 require manually specifying clocking.
790 modprobe i810_audio clocking=48000
793 DEF("device", HAS_ARG, QEMU_OPTION_device,
794 "-device driver[,prop[=value][,...]]\n"
795 " add device (based on driver)\n"
796 " prop=value,... sets driver properties\n"
797 " use '-device help' to print all possible drivers\n"
798 " use '-device driver,help' to print all possible properties\n",
801 ``-device driver[,prop[=value][,...]]``
802 Add device driver. prop=value sets driver properties. Valid
803 properties depend on the driver. To get help on possible drivers and
804 properties, use ``-device help`` and ``-device driver,help``.
808 ``-device ipmi-bmc-sim,id=id[,slave_addr=val][,sdrfile=file][,furareasize=val][,furdatafile=file][,guid=uuid]``
809 Add an IPMI BMC. This is a simulation of a hardware management
810 interface processor that normally sits on a system. It provides a
811 watchdog and the ability to reset and power control the system. You
812 need to connect this to an IPMI interface to make it useful
814 The IPMI slave address to use for the BMC. The default is 0x20. This
815 address is the BMC's address on the I2C network of management
816 controllers. If you don't know what this means, it is safe to ignore
820 The BMC id for interfaces to use this device.
823 Define slave address to use for the BMC. The default is 0x20.
826 file containing raw Sensor Data Records (SDR) data. The default
830 size of a Field Replaceable Unit (FRU) area. The default is
834 file containing raw Field Replaceable Unit (FRU) inventory data.
838 value for the GUID for the BMC, in standard UUID format. If this
839 is set, get "Get GUID" command to the BMC will return it.
840 Otherwise "Get GUID" will return an error.
842 ``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
843 Add a connection to an external IPMI BMC simulator. Instead of
844 locally emulating the BMC like the above item, instead connect to an
845 external entity that provides the IPMI services.
847 A connection is made to an external BMC simulator. If you do this,
848 it is strongly recommended that you use the "reconnect=" chardev
849 option to reconnect to the simulator if the connection is lost. Note
850 that if this is not used carefully, it can be a security issue, as
851 the interface has the ability to send resets, NMIs, and power off
852 the VM. It's best if QEMU makes a connection to an external
853 simulator running on a secure port on localhost, so neither the
854 simulator nor QEMU is exposed to any outside network.
856 See the "lanserv/README.vm" file in the OpenIPMI library for more
857 details on the external interface.
859 ``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
860 Add a KCS IPMI interafce on the ISA bus. This also adds a
861 corresponding ACPI and SMBIOS entries, if appropriate.
864 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
868 Define the I/O address of the interface. The default is 0xca0
872 Define the interrupt to use. The default is 5. To disable
873 interrupts, set this to 0.
875 ``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
876 Like the KCS interface, but defines a BT interface. The default port
877 is 0xe4 and the default interrupt is 5.
880 DEF("name", HAS_ARG, QEMU_OPTION_name,
881 "-name string1[,process=string2][,debug-threads=on|off]\n"
882 " set the name of the guest\n"
883 " string1 sets the window title and string2 the process name\n"
884 " When debug-threads is enabled, individual threads are given a separate name\n"
885 " NOTE: The thread names are for debugging and not a stable API.\n",
889 Sets the name of the guest. This name will be displayed in the SDL
890 window caption. The name will also be used for the VNC server. Also
891 optionally set the top visible process name in Linux. Naming of
892 individual threads can also be enabled on Linux to aid debugging.
895 DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
896 "-uuid %08x-%04x-%04x-%04x-%012x\n"
897 " specify machine UUID\n", QEMU_ARCH_ALL)
905 DEFHEADING(Block device options:)
907 DEF("fda", HAS_ARG, QEMU_OPTION_fda,
908 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
909 DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
914 Use file as floppy disk 0/1 image (see
915 :ref:`disk_005fimages`).
918 DEF("hda", HAS_ARG, QEMU_OPTION_hda,
919 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL)
920 DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
921 DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
922 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL)
923 DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
932 Use file as hard disk 0, 1, 2 or 3 image (see
933 :ref:`disk_005fimages`).
936 DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
937 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n",
941 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at
942 the same time). You can use the host CD-ROM by using ``/dev/cdrom``
946 DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
947 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
948 " [,cache.direct=on|off][,cache.no-flush=on|off]\n"
949 " [,read-only=on|off][,auto-read-only=on|off]\n"
950 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
951 " [,driver specific parameters...]\n"
952 " configure a block backend\n", QEMU_ARCH_ALL)
954 ``-blockdev option[,option[,option[,...]]]``
955 Define a new block driver node. Some of the options apply to all
956 block drivers, other options are only accepted for a specific block
957 driver. See below for a list of generic options and options for the
958 most common block drivers.
960 Options that expect a reference to another node (e.g. ``file``) can
961 be given in two ways. Either you specify the node name of an already
962 existing node (file=node-name), or you define a new node inline,
963 adding options for the referenced node after a dot
964 (file.filename=path,file.aio=native).
966 A block driver node created with ``-blockdev`` can be used for a
967 guest device by specifying its node name for the ``drive`` property
968 in a ``-device`` argument that defines a block device.
970 ``Valid options for any block driver node:``
972 Specifies the block driver to use for the given node.
975 This defines the name of the block driver node by which it
976 will be referenced later. The name must be unique, i.e. it
977 must not match the name of a different block driver node, or
978 (if you use ``-drive`` as well) the ID of a drive.
980 If no node name is specified, it is automatically generated.
981 The generated node name is not intended to be predictable
982 and changes between QEMU invocations. For the top level, an
983 explicit node name must be specified.
986 Open the node read-only. Guest write attempts will fail.
988 Note that some block drivers support only read-only access,
989 either generally or in certain configurations. In this case,
990 the default value ``read-only=off`` does not work and the
991 option must be specified explicitly.
994 If ``auto-read-only=on`` is set, QEMU may fall back to
995 read-only usage even when ``read-only=off`` is requested, or
996 even switch between modes as needed, e.g. depending on
997 whether the image file is writable or whether a writing user
998 is attached to the node.
1001 Override the image locking system of QEMU by forcing the
1002 node to utilize weaker shared access for permissions where
1003 it would normally request exclusive access. When there is
1004 the potential for multiple instances to have the same file
1005 open (whether this invocation of QEMU is the first or the
1006 second instance), both instances must permit shared access
1007 for the second instance to succeed at opening the file.
1009 Enabling ``force-share=on`` requires ``read-only=on``.
1012 The host page cache can be avoided with ``cache.direct=on``.
1013 This will attempt to do disk IO directly to the guest's
1014 memory. QEMU may still perform an internal copy of the data.
1017 In case you don't care about data integrity over host
1018 failures, you can use ``cache.no-flush=on``. This option
1019 tells QEMU that it never needs to write any data to the disk
1020 but can instead keep things in cache. If anything goes
1021 wrong, like your host losing power, the disk storage getting
1022 disconnected accidentally, etc. your image will most
1023 probably be rendered unusable.
1026 discard is one of "ignore" (or "off") or "unmap" (or "on")
1027 and controls whether ``discard`` (also known as ``trim`` or
1028 ``unmap``) requests are ignored or passed to the filesystem.
1029 Some machine types may not support discard requests.
1031 ``detect-zeroes=detect-zeroes``
1032 detect-zeroes is "off", "on" or "unmap" and enables the
1033 automatic conversion of plain zero writes by the OS to
1034 driver specific optimized zero write commands. You may even
1035 choose "unmap" if discard is set to "unmap" to allow a zero
1036 write to be converted to an ``unmap`` operation.
1038 ``Driver-specific options for file``
1039 This is the protocol-level block driver for accessing regular
1043 The path to the image file in the local filesystem
1046 Specifies the AIO backend (threads/native, default: threads)
1049 Specifies whether the image file is protected with Linux OFD
1050 / POSIX locks. The default is to use the Linux Open File
1051 Descriptor API if available, otherwise no lock is applied.
1052 (auto/on/off, default: auto)
1058 -blockdev driver=file,node-name=disk,filename=disk.img
1060 ``Driver-specific options for raw``
1061 This is the image format block driver for raw images. It is
1062 usually stacked on top of a protocol level block driver such as
1066 Reference to or definition of the data source block driver
1067 node (e.g. a ``file`` driver node)
1073 -blockdev driver=file,node-name=disk_file,filename=disk.img
1074 -blockdev driver=raw,node-name=disk,file=disk_file
1080 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1082 ``Driver-specific options for qcow2``
1083 This is the image format block driver for qcow2 images. It is
1084 usually stacked on top of a protocol level block driver such as
1088 Reference to or definition of the data source block driver
1089 node (e.g. a ``file`` driver node)
1092 Reference to or definition of the backing file block device
1093 (default is taken from the image file). It is allowed to
1094 pass ``null`` here in order to disable the default backing
1098 Whether to enable the lazy refcounts feature (on/off;
1099 default is taken from the image file)
1102 The maximum total size of the L2 table and refcount block
1103 caches in bytes (default: the sum of l2-cache-size and
1104 refcount-cache-size)
1107 The maximum size of the L2 table cache in bytes (default: if
1108 cache-size is not specified - 32M on Linux platforms, and 8M
1109 on non-Linux platforms; otherwise, as large as possible
1110 within the cache-size, while permitting the requested or the
1111 minimal refcount cache size)
1113 ``refcount-cache-size``
1114 The maximum size of the refcount block cache in bytes
1115 (default: 4 times the cluster size; or if cache-size is
1116 specified, the part of it which is not used for the L2
1119 ``cache-clean-interval``
1120 Clean unused entries in the L2 and refcount caches. The
1121 interval is in seconds. The default value is 600 on
1122 supporting platforms, and 0 on other platforms. Setting it
1123 to 0 disables this feature.
1125 ``pass-discard-request``
1126 Whether discard requests to the qcow2 device should be
1127 forwarded to the data source (on/off; default: on if
1128 discard=unmap is specified, off otherwise)
1130 ``pass-discard-snapshot``
1131 Whether discard requests for the data source should be
1132 issued when a snapshot operation (e.g. deleting a snapshot)
1133 frees clusters in the qcow2 file (on/off; default: on)
1135 ``pass-discard-other``
1136 Whether discard requests for the data source should be
1137 issued on other occasions where a cluster gets freed
1138 (on/off; default: off)
1141 Which overlap checks to perform for writes to the image
1142 (none/constant/cached/all; default: cached). For details or
1143 finer granularity control refer to the QAPI documentation of
1150 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1151 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1157 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1159 ``Driver-specific options for other drivers``
1160 Please refer to the QAPI documentation of the ``blockdev-add``
1164 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1165 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1166 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1167 " [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1168 " [,werror=ignore|stop|report|enospc][,id=name][,aio=threads|native]\n"
1169 " [,readonly=on|off][,copy-on-read=on|off]\n"
1170 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1171 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1172 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1173 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1174 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1175 " [[,iops_size=is]]\n"
1177 " use 'file' as a drive image\n", QEMU_ARCH_ALL)
1179 ``-drive option[,option[,option[,...]]]``
1180 Define a new drive. This includes creating a block driver node (the
1181 backend) as well as a guest device, and is mostly a shortcut for
1182 defining the corresponding ``-blockdev`` and ``-device`` options.
1184 ``-drive`` accepts all options that are accepted by ``-blockdev``.
1185 In addition, it knows the following options:
1188 This option defines which disk image (see
1189 :ref:`disk_005fimages`) to use with this drive. If
1190 the filename contains comma, you must double it (for instance,
1191 "file=my,,file" to use file "my,file").
1193 Special files such as iSCSI devices can be specified using
1194 protocol specific URLs. See the section for "Device URL Syntax"
1195 for more information.
1198 This option defines on which type on interface the drive is
1199 connected. Available types are: ide, scsi, sd, mtd, floppy,
1200 pflash, virtio, none.
1202 ``bus=bus,unit=unit``
1203 These options define where is connected the drive by defining
1204 the bus number and the unit id.
1207 This option defines where is connected the drive by using an
1208 index in the list of available connectors of a given interface
1212 This option defines the type of the media: disk or cdrom.
1214 ``snapshot=snapshot``
1215 snapshot is "on" or "off" and controls snapshot mode for the
1216 given drive (see ``-snapshot``).
1219 cache is "none", "writeback", "unsafe", "directsync" or
1220 "writethrough" and controls how the host cache is used to access
1221 block data. This is a shortcut that sets the ``cache.direct``
1222 and ``cache.no-flush`` options (as in ``-blockdev``), and
1223 additionally ``cache.writeback``, which provides a default for
1224 the ``write-cache`` option of block guest devices (as in
1225 ``-device``). The modes correspond to the following settings:
1227 ============= =============== ============ ==============
1228 \ cache.writeback cache.direct cache.no-flush
1229 ============= =============== ============ ==============
1230 writeback on off off
1232 writethrough off off off
1233 directsync off on off
1235 ============= =============== ============ ==============
1237 The default mode is ``cache=writeback``.
1240 aio is "threads", or "native" and selects between pthread based
1241 disk I/O and native Linux AIO.
1244 Specify which disk format will be used rather than detecting the
1245 format. Can be used to specify format=raw to avoid interpreting
1246 an untrusted format header.
1248 ``werror=action,rerror=action``
1249 Specify which action to take on write and read errors. Valid
1250 actions are: "ignore" (ignore the error and try to continue),
1251 "stop" (pause QEMU), "report" (report the error to the guest),
1252 "enospc" (pause QEMU only if the host disk is full; report the
1253 error to the guest otherwise). The default setting is
1254 ``werror=enospc`` and ``rerror=report``.
1256 ``copy-on-read=copy-on-read``
1257 copy-on-read is "on" or "off" and enables whether to copy read
1258 backing file sectors into the image file.
1260 ``bps=b,bps_rd=r,bps_wr=w``
1261 Specify bandwidth throttling limits in bytes per second, either
1262 for all request types or for reads or writes only. Small values
1263 can lead to timeouts or hangs inside the guest. A safe minimum
1264 for disks is 2 MB/s.
1266 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
1267 Specify bursts in bytes per second, either for all request types
1268 or for reads or writes only. Bursts allow the guest I/O to spike
1269 above the limit temporarily.
1271 ``iops=i,iops_rd=r,iops_wr=w``
1272 Specify request rate limits in requests per second, either for
1273 all request types or for reads or writes only.
1275 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
1276 Specify bursts in requests per second, either for all request
1277 types or for reads or writes only. Bursts allow the guest I/O to
1278 spike above the limit temporarily.
1281 Let every is bytes of a request count as a new request for iops
1282 throttling purposes. Use this option to prevent guests from
1283 circumventing iops limits by sending fewer but larger requests.
1286 Join a throttling quota group with given name g. All drives that
1287 are members of the same group are accounted for together. Use
1288 this option to prevent guests from circumventing throttling
1289 limits by using many small disks instead of a single larger
1292 By default, the ``cache.writeback=on`` mode is used. It will report
1293 data writes as completed as soon as the data is present in the host
1294 page cache. This is safe as long as your guest OS makes sure to
1295 correctly flush disk caches where needed. If your guest OS does not
1296 handle volatile disk write caches correctly and your host crashes or
1297 loses power, then the guest may experience data corruption.
1299 For such guests, you should consider using ``cache.writeback=off``.
1300 This means that the host page cache will be used to read and write
1301 data, but write notification will be sent to the guest only after
1302 QEMU has made sure to flush each write to the disk. Be aware that
1303 this has a major impact on performance.
1305 When using the ``-snapshot`` option, unsafe caching is always used.
1307 Copy-on-read avoids accessing the same backing file sectors
1308 repeatedly and is useful when the backing file is over a slow
1309 network. By default copy-on-read is off.
1311 Instead of ``-cdrom`` you can use:
1315 |qemu_system| -drive file=file,index=2,media=cdrom
1317 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:
1321 |qemu_system| -drive file=file,index=0,media=disk
1322 |qemu_system| -drive file=file,index=1,media=disk
1323 |qemu_system| -drive file=file,index=2,media=disk
1324 |qemu_system| -drive file=file,index=3,media=disk
1326 You can open an image using pre-opened file descriptors from an fd
1332 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
1333 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
1334 -drive file=/dev/fdset/2,index=0,media=disk
1336 You can connect a CDROM to the slave of ide0:
1340 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom
1342 If you don't specify the "file=" argument, you define an empty
1347 |qemu_system_x86| -drive if=ide,index=1,media=cdrom
1349 Instead of ``-fda``, ``-fdb``, you can use:
1353 |qemu_system_x86| -drive file=file,index=0,if=floppy
1354 |qemu_system_x86| -drive file=file,index=1,if=floppy
1356 By default, interface is "ide" and index is automatically
1361 |qemu_system_x86| -drive file=a -drive file=b"
1363 is interpreted like:
1367 |qemu_system_x86| -hda a -hdb b
1370 DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1371 "-mtdblock file use 'file' as on-board Flash memory image\n",
1375 Use file as on-board Flash memory image.
1378 DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1379 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1382 Use file as SecureDigital card image.
1385 DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
1386 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
1389 Use file as a parallel flash image.
1392 DEF("snapshot", 0, QEMU_OPTION_snapshot,
1393 "-snapshot write to temporary files instead of disk image files\n",
1397 Write to temporary files instead of disk image files. In this case,
1398 the raw disk image you use is not written back. You can however
1399 force the write back by pressing C-a s (see
1400 :ref:`disk_005fimages`).
1403 DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1404 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1405 " [,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode]\n"
1406 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1407 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1408 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1409 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1410 " [[,throttling.iops-size=is]]\n"
1411 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly]\n"
1412 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly]\n"
1413 "-fsdev synth,id=id\n",
1417 ``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]``
1419 ``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly]``
1421 ``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly]``
1423 ``-fsdev synth,id=id[,readonly]``
1424 Define a new file system device. Valid options are:
1427 Accesses to the filesystem are done by QEMU.
1430 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1433 Synthetic filesystem, only used by QTests.
1436 Specifies identifier for this device.
1439 Specifies the export path for the file system device. Files
1440 under this path will be available to the 9p client on the guest.
1442 ``security_model=security_model``
1443 Specifies the security model to be used for this export path.
1444 Supported security models are "passthrough", "mapped-xattr",
1445 "mapped-file" and "none". In "passthrough" security model, files
1446 are stored using the same credentials as they are created on the
1447 guest. This requires QEMU to run as root. In "mapped-xattr"
1448 security model, some of the file attributes like uid, gid, mode
1449 bits and link target are stored as file attributes. For
1450 "mapped-file" these attributes are stored in the hidden
1451 .virtfs\_metadata directory. Directories exported by this
1452 security model cannot interact with other unix tools. "none"
1453 security model is same as passthrough except the sever won't
1454 report failures if it fails to set file attributes like
1455 ownership. Security model is mandatory only for local fsdriver.
1456 Other fsdrivers (like proxy) don't take security model as a
1459 ``writeout=writeout``
1460 This is an optional argument. The only supported value is
1461 "immediate". This means that host page cache will be used to
1462 read and write data but write notification will be sent to the
1463 guest only when the data has been reported as written by the
1467 Enables exporting 9p share as a readonly mount for guests. By
1468 default read-write access is given.
1471 Enables proxy filesystem driver to use passed socket file for
1472 communicating with virtfs-proxy-helper(1).
1475 Enables proxy filesystem driver to use passed socket descriptor
1476 for communicating with virtfs-proxy-helper(1). Usually a helper
1477 like libvirt will create socketpair and pass one of the fds as
1481 Specifies the default mode for newly created files on the host.
1482 Works only with security models "mapped-xattr" and
1486 Specifies the default mode for newly created directories on the
1487 host. Works only with security models "mapped-xattr" and
1490 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w``
1491 Specify bandwidth throttling limits in bytes per second, either
1492 for all request types or for reads or writes only.
1494 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm``
1495 Specify bursts in bytes per second, either for all request types
1496 or for reads or writes only. Bursts allow the guest I/O to spike
1497 above the limit temporarily.
1499 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w``
1500 Specify request rate limits in requests per second, either for
1501 all request types or for reads or writes only.
1503 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm``
1504 Specify bursts in requests per second, either for all request
1505 types or for reads or writes only. Bursts allow the guest I/O to
1506 spike above the limit temporarily.
1508 ``throttling.iops-size=is``
1509 Let every is bytes of a request count as a new request for iops
1510 throttling purposes.
1512 -fsdev option is used along with -device driver "virtio-9p-...".
1514 ``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag``
1515 Options for virtio-9p-... driver are:
1518 Specifies the variant to be used. Supported values are "pci",
1519 "ccw" or "device", depending on the machine type.
1522 Specifies the id value specified along with -fsdev option.
1524 ``mount_tag=mount_tag``
1525 Specifies the tag name to be used by the guest to mount this
1529 DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1530 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1531 " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1532 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly]\n"
1533 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly]\n"
1534 "-virtfs synth,mount_tag=tag[,id=id][,readonly]\n",
1538 ``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]``
1540 ``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly]``
1542 ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly]``
1544 ``-virtfs synth,mount_tag=mount_tag``
1545 Define a new filesystem device and expose it to the guest using a
1546 virtio-9p-device. The general form of a Virtual File system
1547 pass-through options are:
1550 Accesses to the filesystem are done by QEMU.
1553 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1556 Synthetic filesystem, only used by QTests.
1559 Specifies identifier for the filesystem device
1562 Specifies the export path for the file system device. Files
1563 under this path will be available to the 9p client on the guest.
1565 ``security_model=security_model``
1566 Specifies the security model to be used for this export path.
1567 Supported security models are "passthrough", "mapped-xattr",
1568 "mapped-file" and "none". In "passthrough" security model, files
1569 are stored using the same credentials as they are created on the
1570 guest. This requires QEMU to run as root. In "mapped-xattr"
1571 security model, some of the file attributes like uid, gid, mode
1572 bits and link target are stored as file attributes. For
1573 "mapped-file" these attributes are stored in the hidden
1574 .virtfs\_metadata directory. Directories exported by this
1575 security model cannot interact with other unix tools. "none"
1576 security model is same as passthrough except the sever won't
1577 report failures if it fails to set file attributes like
1578 ownership. Security model is mandatory only for local fsdriver.
1579 Other fsdrivers (like proxy) don't take security model as a
1582 ``writeout=writeout``
1583 This is an optional argument. The only supported value is
1584 "immediate". This means that host page cache will be used to
1585 read and write data but write notification will be sent to the
1586 guest only when the data has been reported as written by the
1590 Enables exporting 9p share as a readonly mount for guests. By
1591 default read-write access is given.
1594 Enables proxy filesystem driver to use passed socket file for
1595 communicating with virtfs-proxy-helper(1). Usually a helper like
1596 libvirt will create socketpair and pass one of the fds as
1600 Enables proxy filesystem driver to use passed 'sock\_fd' as the
1601 socket descriptor for interfacing with virtfs-proxy-helper(1).
1604 Specifies the default mode for newly created files on the host.
1605 Works only with security models "mapped-xattr" and
1609 Specifies the default mode for newly created directories on the
1610 host. Works only with security models "mapped-xattr" and
1613 ``mount_tag=mount_tag``
1614 Specifies the tag name to be used by the guest to mount this
1617 ``multidevs=multidevs``
1618 Specifies how to deal with multiple devices being shared with a
1619 9p export. Supported behaviours are either "remap", "forbid" or
1620 "warn". The latter is the default behaviour on which virtfs 9p
1621 expects only one device to be shared with the same export, and
1622 if more than one device is shared and accessed via the same 9p
1623 export then only a warning message is logged (once) by qemu on
1624 host side. In order to avoid file ID collisions on guest you
1625 should either create a separate virtfs export for each device to
1626 be shared with guests (recommended way) or you might use "remap"
1627 instead which allows you to share multiple devices with only one
1628 export instead, which is achieved by remapping the original
1629 inode numbers from host to guest in a way that would prevent
1630 such collisions. Remapping inodes in such use cases is required
1631 because the original device IDs from host are never passed and
1632 exposed on guest. Instead all files of an export shared with
1633 virtfs always share the same device id on guest. So two files
1634 with identical inode numbers but from actually different devices
1635 on host would otherwise cause a file ID collision and hence
1636 potential misbehaviours on guest. "forbid" on the other hand
1637 assumes like "warn" that only one device is shared by the same
1638 export, however it will not only log a warning message but also
1639 deny access to additional devices on guest. Note though that
1640 "forbid" does currently not block all possible file access
1641 operations (e.g. readdir() would still return entries from other
1645 DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
1646 "-iscsi [user=user][,password=password]\n"
1647 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
1648 " [,initiator-name=initiator-iqn][,id=target-iqn]\n"
1649 " [,timeout=timeout]\n"
1650 " iSCSI session parameters\n", QEMU_ARCH_ALL)
1654 Configure iSCSI session parameters.
1659 DEFHEADING(USB options:)
1661 DEF("usb", 0, QEMU_OPTION_usb,
1662 "-usb enable on-board USB host controller (if not enabled by default)\n",
1666 Enable USB emulation on machine types with an on-board USB host
1667 controller (if not enabled by default). Note that on-board USB host
1668 controllers may not support USB 3.0. In this case
1669 ``-device qemu-xhci`` can be used instead on machines with PCI.
1672 DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
1673 "-usbdevice name add the host or guest USB device 'name'\n",
1676 ``-usbdevice devname``
1677 Add the USB device devname. Note that this option is deprecated,
1678 please use ``-device usb-...`` instead. See
1679 :ref:`usb_005fdevices`.
1682 Virtual Mouse. This will override the PS/2 mouse emulation when
1686 Pointer device that uses absolute coordinates (like a
1687 touchscreen). This means QEMU is able to report the mouse
1688 position without having to grab the mouse. Also overrides the
1689 PS/2 mouse emulation when activated.
1692 Braille device. This will use BrlAPI to display the braille
1693 output on a real or fake device.
1698 DEFHEADING(Display options:)
1700 DEF("display", HAS_ARG, QEMU_OPTION_display,
1701 #if defined(CONFIG_SPICE)
1702 "-display spice-app[,gl=on|off]\n"
1704 #if defined(CONFIG_SDL)
1705 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off]\n"
1706 " [,window_close=on|off][,gl=on|core|es|off]\n"
1708 #if defined(CONFIG_GTK)
1709 "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
1711 #if defined(CONFIG_VNC)
1712 "-display vnc=<display>[,<optargs>]\n"
1714 #if defined(CONFIG_CURSES)
1715 "-display curses[,charset=<encoding>]\n"
1717 #if defined(CONFIG_OPENGL)
1718 "-display egl-headless[,rendernode=<file>]\n"
1721 " select display backend type\n"
1722 " The default display is equivalent to\n "
1723 #if defined(CONFIG_GTK)
1724 "\"-display gtk\"\n"
1725 #elif defined(CONFIG_SDL)
1726 "\"-display sdl\"\n"
1727 #elif defined(CONFIG_COCOA)
1728 "\"-display cocoa\"\n"
1729 #elif defined(CONFIG_VNC)
1730 "\"-vnc localhost:0,to=99,id=default\"\n"
1732 "\"-display none\"\n"
1737 Select type of display to use. This option is a replacement for the
1738 old style -sdl/-curses/... options. Use ``-display help`` to list
1739 the available display types. Valid values for type are
1742 Display video output via SDL (usually in a separate graphics
1743 window; see the SDL documentation for other possibilities).
1746 Display video output via curses. For graphics device models
1747 which support a text mode, QEMU can display this output using a
1748 curses/ncurses interface. Nothing is displayed when the graphics
1749 device is in graphical mode or if the graphics device does not
1750 support a text mode. Generally only the VGA device models
1751 support text mode. The font charset used by the guest can be
1752 specified with the ``charset`` option, for example
1753 ``charset=CP850`` for IBM CP850 encoding. The default is
1757 Do not display video output. The guest will still see an
1758 emulated graphics card, but its output will not be displayed to
1759 the QEMU user. This option differs from the -nographic option in
1760 that it only affects what is done with video output; -nographic
1761 also changes the destination of the serial and parallel port
1765 Display video output in a GTK window. This interface provides
1766 drop-down menus and other UI elements to configure and control
1767 the VM during runtime.
1770 Start a VNC server on display <arg>
1773 Offload all OpenGL operations to a local DRI device. For any
1774 graphical display, this display needs to be paired with either
1775 VNC or SPICE displays.
1778 Start QEMU as a Spice server and launch the default Spice client
1779 application. The Spice server will redirect the serial consoles
1780 and QEMU monitors. (Since 4.0)
1783 DEF("nographic", 0, QEMU_OPTION_nographic,
1784 "-nographic disable graphical output and redirect serial I/Os to console\n",
1788 Normally, if QEMU is compiled with graphical window support, it
1789 displays output such as guest graphics, guest console, and the QEMU
1790 monitor in a window. With this option, you can totally disable
1791 graphical output so that QEMU is a simple command line application.
1792 The emulated serial port is redirected on the console and muxed with
1793 the monitor (unless redirected elsewhere explicitly). Therefore, you
1794 can still use QEMU to debug a Linux kernel with a serial console.
1795 Use C-a h for help on switching between the console and monitor.
1798 DEF("curses", 0, QEMU_OPTION_curses,
1799 "-curses shorthand for -display curses\n",
1803 Normally, if QEMU is compiled with graphical window support, it
1804 displays output such as guest graphics, guest console, and the QEMU
1805 monitor in a window. With this option, QEMU can display the VGA
1806 output when in text mode using a curses/ncurses interface. Nothing
1807 is displayed in graphical mode.
1810 DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
1811 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
1815 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
1816 this also affects the special keys (for fullscreen, monitor-mode
1820 DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
1821 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
1825 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
1826 also affects the special keys (for fullscreen, monitor-mode
1830 DEF("no-quit", 0, QEMU_OPTION_no_quit,
1831 "-no-quit disable SDL window close capability\n", QEMU_ARCH_ALL)
1834 Disable SDL window close capability.
1837 DEF("sdl", 0, QEMU_OPTION_sdl,
1838 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL)
1844 DEF("spice", HAS_ARG, QEMU_OPTION_spice,
1845 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
1846 " [,x509-key-file=<file>][,x509-key-password=<file>]\n"
1847 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
1848 " [,x509-dh-key-file=<file>][,addr=addr][,ipv4|ipv6|unix]\n"
1849 " [,tls-ciphers=<list>]\n"
1850 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
1851 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
1852 " [,sasl][,password=<secret>][,disable-ticketing]\n"
1853 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
1854 " [,jpeg-wan-compression=[auto|never|always]]\n"
1855 " [,zlib-glz-wan-compression=[auto|never|always]]\n"
1856 " [,streaming-video=[off|all|filter]][,disable-copy-paste]\n"
1857 " [,disable-agent-file-xfer][,agent-mouse=[on|off]]\n"
1858 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
1859 " [,gl=[on|off]][,rendernode=<file>]\n"
1861 " at least one of {port, tls-port} is mandatory\n",
1864 ``-spice option[,option[,...]]``
1865 Enable the spice remote desktop protocol. Valid options are
1868 Set the TCP port spice is listening on for plaintext channels.
1871 Set the IP address spice is listening on. Default is any
1874 ``ipv4``; \ ``ipv6``; \ ``unix``
1875 Force using the specified IP version.
1877 ``password=<secret>``
1878 Set the password you need to authenticate.
1881 Require that the client use SASL to authenticate with the spice.
1882 The exact choice of authentication method used is controlled
1883 from the system / user's SASL configuration file for the 'qemu'
1884 service. This is typically found in /etc/sasl2/qemu.conf. If
1885 running QEMU as an unprivileged user, an environment variable
1886 SASL\_CONF\_PATH can be used to make it search alternate
1887 locations for the service config. While some SASL auth methods
1888 can also provide data encryption (eg GSSAPI), it is recommended
1889 that SASL always be combined with the 'tls' and 'x509' settings
1890 to enable use of SSL and server certificates. This ensures a
1891 data encryption preventing compromise of authentication
1894 ``disable-ticketing``
1895 Allow client connects without authentication.
1897 ``disable-copy-paste``
1898 Disable copy paste between the client and the guest.
1900 ``disable-agent-file-xfer``
1901 Disable spice-vdagent based file-xfer between the client and the
1905 Set the TCP port spice is listening on for encrypted channels.
1908 Set the x509 file directory. Expects same filenames as -vnc
1911 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>``
1912 The x509 file names can also be configured individually.
1914 ``tls-ciphers=<list>``
1915 Specify which ciphers to use.
1917 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]``
1918 Force specific channel to be used with or without TLS
1919 encryption. The options can be specified multiple times to
1920 configure multiple channels. The special name "default" can be
1921 used to set the default mode. For channels which are not
1922 explicitly forced into one mode the spice client is allowed to
1923 pick tls/plaintext as he pleases.
1925 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]``
1926 Configure image compression (lossless). Default is auto\_glz.
1928 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]``
1929 Configure wan image compression (lossy for slow links). Default
1932 ``streaming-video=[off|all|filter]``
1933 Configure video stream detection. Default is off.
1935 ``agent-mouse=[on|off]``
1936 Enable/disable passing mouse events via vdagent. Default is on.
1938 ``playback-compression=[on|off]``
1939 Enable/disable audio stream compression (using celt 0.5.1).
1942 ``seamless-migration=[on|off]``
1943 Enable/disable spice seamless migration. Default is off.
1946 Enable/disable OpenGL context. Default is off.
1948 ``rendernode=<file>``
1949 DRM render node for OpenGL rendering. If not specified, it will
1950 pick the first available. (Since 2.9)
1953 DEF("portrait", 0, QEMU_OPTION_portrait,
1954 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n",
1958 Rotate graphical output 90 deg left (only PXA LCD).
1961 DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
1962 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n",
1966 Rotate graphical output some deg left (only PXA LCD).
1969 DEF("vga", HAS_ARG, QEMU_OPTION_vga,
1970 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
1971 " select video card type\n", QEMU_ARCH_ALL)
1974 Select type of VGA card to emulate. Valid values for type are
1977 Cirrus Logic GD5446 Video card. All Windows versions starting
1978 from Windows 95 should recognize and use this graphic card. For
1979 optimal performances, use 16 bit color depth in the guest and
1980 the host OS. (This card was the default before QEMU 2.2)
1983 Standard VGA card with Bochs VBE extensions. If your guest OS
1984 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if
1985 you want to use high resolution modes (>= 1280x1024x16) then you
1986 should use this option. (This card is the default since QEMU
1990 VMWare SVGA-II compatible adapter. Use it if you have
1991 sufficiently recent XFree86/XOrg server or Windows guest with a
1992 driver for this card.
1995 QXL paravirtual graphic card. It is VGA compatible (including
1996 VESA 2.0 VBE support). Works best with qxl guest drivers
1997 installed though. Recommended choice when using the spice
2001 (sun4m only) Sun TCX framebuffer. This is the default
2002 framebuffer for sun4m machines and offers both 8-bit and 24-bit
2003 colour depths at a fixed resolution of 1024x768.
2006 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit
2007 framebuffer for sun4m machines available in both 1024x768
2008 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people
2009 wishing to run older Solaris versions.
2018 DEF("full-screen", 0, QEMU_OPTION_full_screen,
2019 "-full-screen start in full screen\n", QEMU_ARCH_ALL)
2022 Start in full screen.
2025 DEF("g", HAS_ARG, QEMU_OPTION_g ,
2026 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n",
2027 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K)
2029 ``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]``
2030 Set the initial graphical resolution and depth (PPC, SPARC only).
2032 For PPC the default is 800x600x32.
2034 For SPARC with the TCX graphics device, the default is 1024x768x8
2035 with the option of 1024x768x24. For cgthree, the default is
2036 1024x768x8 with the option of 1152x900x8 for people who wish to use
2040 DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
2041 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
2043 ``-vnc display[,option[,option[,...]]]``
2044 Normally, if QEMU is compiled with graphical window support, it
2045 displays output such as guest graphics, guest console, and the QEMU
2046 monitor in a window. With this option, you can have QEMU listen on
2047 VNC display display and redirect the VGA display over the VNC
2048 session. It is very useful to enable the usb tablet device when
2049 using this option (option ``-device usb-tablet``). When using the
2050 VNC display, you must use the ``-k`` parameter to set the keyboard
2051 layout if you are not using en-us. Valid syntax for the display is
2054 With this option, QEMU will try next available VNC displays,
2055 until the number L, if the origianlly defined "-vnc display" is
2056 not available, e.g. port 5900+display is already used by another
2057 application. By default, to=0.
2060 TCP connections will only be allowed from host on display d. By
2061 convention the TCP port is 5900+d. Optionally, host can be
2062 omitted in which case the server will accept connections from
2066 Connections will be allowed over UNIX domain sockets where path
2067 is the location of a unix socket to listen for connections on.
2070 VNC is initialized but not started. The monitor ``change``
2071 command can be used to later start the VNC server.
2073 Following the display value there may be one or more option flags
2074 separated by commas. Valid options are
2077 Connect to a listening VNC client via a "reverse" connection.
2078 The client is specified by the display. For reverse network
2079 connections (host:d,``reverse``), the d argument is a TCP port
2080 number, not a display number.
2083 Opens an additional TCP listening port dedicated to VNC
2084 Websocket connections. If a bare websocket option is given, the
2085 Websocket port is 5700+display. An alternative port can be
2086 specified with the syntax ``websocket``\ =port.
2088 If host is specified connections will only be allowed from this
2089 host. It is possible to control the websocket listen address
2090 independently, using the syntax ``websocket``\ =host:port.
2092 If no TLS credentials are provided, the websocket connection
2093 runs in unencrypted mode. If TLS credentials are provided, the
2094 websocket connection requires encrypted client connections.
2097 Require that password based authentication is used for client
2100 The password must be set separately using the ``set_password``
2101 command in the :ref:`pcsys_005fmonitor`. The
2102 syntax to change your password is:
2103 ``set_password <protocol> <password>`` where <protocol> could be
2104 either "vnc" or "spice".
2106 If you would like to change <protocol> password expiration, you
2107 should use ``expire_password <protocol> <expiration-time>``
2108 where expiration time could be one of the following options:
2109 now, never, +seconds or UNIX time of expiration, e.g. +60 to
2110 make password expire in 60 seconds, or 1335196800 to make
2111 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for
2112 this date and time).
2114 You can also use keywords "now" or "never" for the expiration
2115 time to allow <protocol> password to expire immediately or never
2119 Provides the ID of a set of TLS credentials to use to secure the
2120 VNC server. They will apply to both the normal VNC server socket
2121 and the websocket socket (if enabled). Setting TLS credentials
2122 will cause the VNC server socket to enable the VeNCrypt auth
2123 mechanism. The credentials should have been previously created
2124 using the ``-object tls-creds`` argument.
2127 Provides the ID of the QAuthZ authorization object against which
2128 the client's x509 distinguished name will validated. This object
2129 is only resolved at time of use, so can be deleted and recreated
2130 on the fly while the VNC server is active. If missing, it will
2131 default to denying access.
2134 Require that the client use SASL to authenticate with the VNC
2135 server. The exact choice of authentication method used is
2136 controlled from the system / user's SASL configuration file for
2137 the 'qemu' service. This is typically found in
2138 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user,
2139 an environment variable SASL\_CONF\_PATH can be used to make it
2140 search alternate locations for the service config. While some
2141 SASL auth methods can also provide data encryption (eg GSSAPI),
2142 it is recommended that SASL always be combined with the 'tls'
2143 and 'x509' settings to enable use of SSL and server
2144 certificates. This ensures a data encryption preventing
2145 compromise of authentication credentials. See the
2146 :ref:`vnc_005fsecurity` section for details on
2147 using SASL authentication.
2150 Provides the ID of the QAuthZ authorization object against which
2151 the client's SASL username will validated. This object is only
2152 resolved at time of use, so can be deleted and recreated on the
2153 fly while the VNC server is active. If missing, it will default
2157 Legacy method for enabling authorization of clients against the
2158 x509 distinguished name and SASL username. It results in the
2159 creation of two ``authz-list`` objects with IDs of
2160 ``vnc.username`` and ``vnc.x509dname``. The rules for these
2161 objects must be configured with the HMP ACL commands.
2163 This option is deprecated and should no longer be used. The new
2164 ``sasl-authz`` and ``tls-authz`` options are a replacement.
2167 Enable lossy compression methods (gradient, JPEG, ...). If this
2168 option is set, VNC client may receive lossy framebuffer updates
2169 depending on its encoding settings. Enabling this option can
2170 save a lot of bandwidth at the expense of quality.
2173 Disable adaptive encodings. Adaptive encodings are enabled by
2174 default. An adaptive encoding will try to detect frequently
2175 updated screen regions, and send updates in these regions using
2176 a lossy encoding (like JPEG). This can be really helpful to save
2177 bandwidth when playing videos. Disabling adaptive encodings
2178 restores the original static behavior of encodings like Tight.
2180 ``share=[allow-exclusive|force-shared|ignore]``
2181 Set display sharing policy. 'allow-exclusive' allows clients to
2182 ask for exclusive access. As suggested by the rfb spec this is
2183 implemented by dropping other connections. Connecting multiple
2184 clients in parallel requires all clients asking for a shared
2185 session (vncviewer: -shared switch). This is the default.
2186 'force-shared' disables exclusive client access. Useful for
2187 shared desktop sessions, where you don't want someone forgetting
2188 specify -shared disconnect everybody else. 'ignore' completely
2189 ignores the shared flag and allows everybody connect
2190 unconditionally. Doesn't conform to the rfb spec but is
2191 traditional QEMU behavior.
2194 Set keyboard delay, for key down and key up events, in
2195 milliseconds. Default is 10. Keyboards are low-bandwidth
2196 devices, so this slowdown can help the device and guest to keep
2197 up and not lose events in case events are arriving in bulk.
2198 Possible causes for the latter are flaky network connections, or
2199 scripts for automated testing.
2201 ``audiodev=audiodev``
2202 Use the specified audiodev when the VNC client requests audio
2203 transmission. When not using an -audiodev argument, this option
2204 must be omitted, otherwise is must be present and specify a
2208 ARCHHEADING(, QEMU_ARCH_I386)
2210 ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2212 DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2213 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n",
2217 Use it when installing Windows 2000 to avoid a disk full bug. After
2218 Windows 2000 is installed, you no longer need this option (this
2219 option slows down the IDE transfers).
2222 DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2223 "-no-fd-bootchk disable boot signature checking for floppy disks\n",
2227 Disable boot signature checking for floppy disks in BIOS. May be
2228 needed to boot from old floppy disks.
2231 DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
2232 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2235 Disable ACPI (Advanced Configuration and Power Interface) support.
2236 Use it if your guest OS complains about ACPI problems (PC target
2240 DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
2241 "-no-hpet disable HPET\n", QEMU_ARCH_I386)
2244 Disable HPET support.
2247 DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2248 "-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"
2249 " ACPI table description\n", QEMU_ARCH_I386)
2251 ``-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]...]``
2252 Add ACPI table with specified header fields and context from
2253 specified files. For file=, take whole ACPI table from the specified
2254 files, including all ACPI headers (possible overridden by other
2255 options). For data=, only data portion of the table is used, all
2256 header information is specified in the command line. If a SLIC table
2257 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
2258 fields will override the same in the RSDT and the FADT (a.k.a.
2259 FACP), in order to ensure the field matches required by the
2260 Microsoft SLIC spec and the ACPI spec.
2263 DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2264 "-smbios file=binary\n"
2265 " load SMBIOS entry from binary file\n"
2266 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2268 " specify SMBIOS type 0 fields\n"
2269 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2270 " [,uuid=uuid][,sku=str][,family=str]\n"
2271 " specify SMBIOS type 1 fields\n"
2272 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2273 " [,asset=str][,location=str]\n"
2274 " specify SMBIOS type 2 fields\n"
2275 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2277 " specify SMBIOS type 3 fields\n"
2278 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2279 " [,asset=str][,part=str]\n"
2280 " specify SMBIOS type 4 fields\n"
2281 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2282 " [,asset=str][,part=str][,speed=%d]\n"
2283 " specify SMBIOS type 17 fields\n",
2284 QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2286 ``-smbios file=binary``
2287 Load SMBIOS entry from binary file.
2289 ``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]``
2290 Specify SMBIOS type 0 fields
2292 ``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]``
2293 Specify SMBIOS type 1 fields
2295 ``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]``
2296 Specify SMBIOS type 2 fields
2298 ``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]``
2299 Specify SMBIOS type 3 fields
2301 ``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]``
2302 Specify SMBIOS type 4 fields
2304 ``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]``
2305 Specify SMBIOS type 17 fields
2310 DEFHEADING(Network options:)
2312 DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2314 "-netdev user,id=str[,ipv4[=on|off]][,net=addr[/mask]][,host=addr]\n"
2315 " [,ipv6[=on|off]][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2316 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2317 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2318 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2320 "[,smb=dir[,smbserver=addr]]\n"
2322 " configure a user mode network backend with ID 'str',\n"
2323 " its DHCP server and optional services\n"
2326 "-netdev tap,id=str,ifname=name\n"
2327 " configure a host TAP network backend with ID 'str'\n"
2329 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2330 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2331 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2333 " configure a host TAP network backend with ID 'str'\n"
2334 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2335 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2336 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2337 " to deconfigure it\n"
2338 " use '[down]script=no' to disable script execution\n"
2339 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2341 " use 'fd=h' to connect to an already opened TAP interface\n"
2342 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2343 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2344 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2345 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2346 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2347 " use vhost=on to enable experimental in kernel accelerator\n"
2348 " (only has effect for virtio guests which use MSIX)\n"
2349 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2350 " use 'vhostfd=h' to connect to an already opened vhost net device\n"
2351 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2352 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2353 " use 'poll-us=n' to speciy the maximum number of microseconds that could be\n"
2354 " spent on busy polling for vhost net\n"
2355 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2356 " configure a host TAP network backend with ID 'str' that is\n"
2357 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2358 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2361 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2362 " [,rxsession=rxsession],txsession=txsession[,ipv6=on/off][,udp=on/off]\n"
2363 " [,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie]\n"
2364 " [,rxcookie=rxcookie][,offset=offset]\n"
2365 " configure a network backend with ID 'str' connected to\n"
2366 " an Ethernet over L2TPv3 pseudowire.\n"
2367 " Linux kernel 3.3+ as well as most routers can talk\n"
2368 " L2TPv3. This transport allows connecting a VM to a VM,\n"
2369 " VM to a router and even VM to Host. It is a nearly-universal\n"
2370 " standard (RFC3931). Note - this implementation uses static\n"
2371 " pre-configured tunnels (same as the Linux kernel).\n"
2372 " use 'src=' to specify source address\n"
2373 " use 'dst=' to specify destination address\n"
2374 " use 'udp=on' to specify udp encapsulation\n"
2375 " use 'srcport=' to specify source udp port\n"
2376 " use 'dstport=' to specify destination udp port\n"
2377 " use 'ipv6=on' to force v6\n"
2378 " L2TPv3 uses cookies to prevent misconfiguration as\n"
2379 " well as a weak security measure\n"
2380 " use 'rxcookie=0x012345678' to specify a rxcookie\n"
2381 " use 'txcookie=0x012345678' to specify a txcookie\n"
2382 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2383 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2384 " use 'pincounter=on' to work around broken counter handling in peer\n"
2385 " use 'offset=X' to add an extra offset between header and data\n"
2387 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2388 " configure a network backend to connect to another network\n"
2389 " using a socket connection\n"
2390 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2391 " configure a network backend to connect to a multicast maddr and port\n"
2392 " use 'localaddr=addr' to specify the host address to send packets from\n"
2393 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2394 " configure a network backend to connect to another network\n"
2395 " using an UDP tunnel\n"
2397 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2398 " configure a network backend to connect to port 'n' of a vde switch\n"
2399 " running on host and listening for incoming connections on 'socketpath'.\n"
2400 " Use group 'groupname' and mode 'octalmode' to change default\n"
2401 " ownership and permissions for communication port.\n"
2403 #ifdef CONFIG_NETMAP
2404 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2405 " attach to the existing netmap-enabled network interface 'name', or to a\n"
2406 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2407 " netmap device, defaults to '/dev/netmap')\n"
2410 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2411 " configure a vhost-user network, backed by a chardev 'dev'\n"
2413 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2414 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2415 DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2426 #ifdef CONFIG_NETMAP
2432 "socket][,option][,...][mac=macaddr]\n"
2433 " initialize an on-board / default host NIC (using MAC address\n"
2434 " macaddr) and connect it to the given host network backend\n"
2435 "-nic none use it alone to have zero network devices (the default is to\n"
2436 " provided a 'user' network connection)\n",
2438 DEF("net", HAS_ARG, QEMU_OPTION_net,
2439 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2440 " configure or create an on-board (or machine default) NIC and\n"
2441 " connect it to hub 0 (please use -nic unless you need a hub)\n"
2451 #ifdef CONFIG_NETMAP
2454 "socket][,option][,option][,...]\n"
2455 " old way to initialize a host network interface\n"
2456 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
2458 ``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]``
2459 This option is a shortcut for configuring both the on-board
2460 (default) guest NIC hardware and the host network backend in one go.
2461 The host backend options are the same as with the corresponding
2462 ``-netdev`` options below. The guest NIC model can be set with
2463 ``model=modelname``. Use ``model=help`` to list the available device
2464 types. The hardware MAC address can be set with ``mac=macaddr``.
2466 The following two example do exactly the same, to show how ``-nic``
2467 can be used to shorten the command line length:
2471 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
2472 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
2475 Indicate that no network devices should be configured. It is used to
2476 override the default configuration (default NIC with "user" host
2477 network backend) which is activated if no other networking options
2480 ``-netdev user,id=id[,option][,option][,...]``
2481 Configure user mode host network backend which requires no
2482 administrator privilege to run. Valid options are:
2485 Assign symbolic name for use in monitor commands.
2487 ``ipv4=on|off and ipv6=on|off``
2488 Specify that either IPv4 or IPv6 must be enabled. If neither is
2489 specified both protocols are enabled.
2492 Set IP network address the guest will see. Optionally specify
2493 the netmask, either in the form a.b.c.d or as number of valid
2494 top-most bits. Default is 10.0.2.0/24.
2497 Specify the guest-visible address of the host. Default is the
2498 2nd IP in the guest network, i.e. x.x.x.2.
2500 ``ipv6-net=addr[/int]``
2501 Set IPv6 network address the guest will see (default is
2502 fec0::/64). The network prefix is given in the usual hexadecimal
2503 IPv6 address notation. The prefix size is optional, and is given
2504 as the number of valid top-most bits (default is 64).
2507 Specify the guest-visible IPv6 address of the host. Default is
2508 the 2nd IPv6 in the guest network, i.e. xxxx::2.
2511 If this option is enabled, the guest will be isolated, i.e. it
2512 will not be able to contact the host and no guest IP packets
2513 will be routed over the host to the outside. This option does
2514 not affect any explicitly set forwarding rules.
2517 Specifies the client hostname reported by the built-in DHCP
2521 Specify the first of the 16 IPs the built-in DHCP server can
2522 assign. Default is the 15th to 31st IP in the guest network,
2523 i.e. x.x.x.15 to x.x.x.31.
2526 Specify the guest-visible address of the virtual nameserver. The
2527 address must be different from the host address. Default is the
2528 3rd IP in the guest network, i.e. x.x.x.3.
2531 Specify the guest-visible address of the IPv6 virtual
2532 nameserver. The address must be different from the host address.
2533 Default is the 3rd IP in the guest network, i.e. xxxx::3.
2535 ``dnssearch=domain``
2536 Provides an entry for the domain-search list sent by the
2537 built-in DHCP server. More than one domain suffix can be
2538 transmitted by specifying this option multiple times. If
2539 supported, this will cause the guest to automatically try to
2540 append the given domain suffix(es) in case a domain name can not
2547 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
2549 ``domainname=domain``
2550 Specifies the client domain name reported by the built-in DHCP
2554 When using the user mode network stack, activate a built-in TFTP
2555 server. The files in dir will be exposed as the root of a TFTP
2556 server. The TFTP client on the guest must be configured in
2557 binary mode (use the command ``bin`` of the Unix TFTP client).
2559 ``tftp-server-name=name``
2560 In BOOTP reply, broadcast name as the "TFTP server name"
2561 (RFC2132 option 66). This can be used to advise the guest to
2562 load boot files or configurations from a different server than
2566 When using the user mode network stack, broadcast file as the
2567 BOOTP filename. In conjunction with ``tftp``, this can be used
2568 to network boot a guest from a local directory.
2570 Example (using pxelinux):
2574 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \
2575 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
2577 ``smb=dir[,smbserver=addr]``
2578 When using the user mode network stack, activate a built-in SMB
2579 server so that Windows OSes can access to the host files in
2580 ``dir`` transparently. The IP address of the SMB server can be
2581 set to addr. By default the 4th IP in the guest network is used,
2584 In the guest Windows OS, the line:
2590 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows
2591 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows
2594 Then ``dir`` can be accessed in ``\\smbserver\qemu``.
2596 Note that a SAMBA server must be installed on the host OS.
2598 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport``
2599 Redirect incoming TCP or UDP connections to the host port
2600 hostport to the guest IP address guestaddr on guest port
2601 guestport. If guestaddr is not specified, its value is x.x.x.15
2602 (default first address given by the built-in DHCP server). By
2603 specifying hostaddr, the rule can be bound to a specific host
2604 interface. If no connection type is set, TCP is used. This
2605 option can be given multiple times.
2607 For example, to redirect host X11 connection from screen 1 to
2608 guest screen 0, use the following:
2613 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
2614 # this host xterm should open in the guest X11 server
2617 To redirect telnet connections from host port 5555 to telnet
2618 port on the guest, use the following:
2623 |qemu_system| -nic user,hostfwd=tcp::5555-:23
2624 telnet localhost 5555
2626 Then when you use on the host ``telnet localhost 5555``, you
2627 connect to the guest telnet server.
2629 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command``
2630 Forward guest TCP connections to the IP address server on port
2631 port to the character device dev or to a program executed by
2632 cmd:command which gets spawned for each connection. This option
2633 can be given multiple times.
2635 You can either use a chardev directly and have that one used
2636 throughout QEMU's lifetime, like in the following example:
2640 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
2641 # the guest accesses it
2642 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
2644 Or you can execute a command on every TCP connection established
2645 by the guest, so that QEMU behaves similar to an inetd process
2646 for that virtual server:
2650 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
2651 # and connect the TCP stream to its stdin/stdout
2652 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
2654 ``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
2655 Configure a host TAP network backend with ID id.
2657 Use the network script file to configure it and the network script
2658 dfile to deconfigure it. If name is not provided, the OS
2659 automatically provides one. The default network configure script is
2660 ``/etc/qemu-ifup`` and the default network deconfigure script is
2661 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
2662 disable script execution.
2664 If running QEMU as an unprivileged user, use the network helper
2665 helper to configure the TAP interface and attach it to the bridge.
2666 The default network helper executable is
2667 ``/path/to/qemu-bridge-helper`` and the default bridge device is
2670 ``fd``\ =h can be used to specify the handle of an already opened
2677 #launch a QEMU instance with the default network script
2678 |qemu_system| linux.img -nic tap
2682 #launch a QEMU instance with two NICs, each one connected
2684 |qemu_system| linux.img \
2685 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \
2686 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
2690 #launch a QEMU instance with the default network helper to
2691 #connect a TAP device to bridge br0
2692 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \
2693 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
2695 ``-netdev bridge,id=id[,br=bridge][,helper=helper]``
2696 Connect a host TAP network interface to a host bridge device.
2698 Use the network helper helper to configure the TAP interface and
2699 attach it to the bridge. The default network helper executable is
2700 ``/path/to/qemu-bridge-helper`` and the default bridge device is
2707 #launch a QEMU instance with the default network helper to
2708 #connect a TAP device to bridge br0
2709 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
2713 #launch a QEMU instance with the default network helper to
2714 #connect a TAP device to bridge qemubr0
2715 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
2717 ``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
2718 This host network backend can be used to connect the guest's network
2719 to another QEMU virtual machine using a TCP socket connection. If
2720 ``listen`` is specified, QEMU waits for incoming connections on port
2721 (host is optional). ``connect`` is used to connect to another QEMU
2722 instance using the ``listen`` option. ``fd``\ =h specifies an
2723 already opened TCP socket.
2729 # launch a first QEMU instance
2730 |qemu_system| linux.img \
2731 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2732 -netdev socket,id=n1,listen=:1234
2733 # connect the network of this instance to the network of the first instance
2734 |qemu_system| linux.img \
2735 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
2736 -netdev socket,id=n2,connect=127.0.0.1:1234
2738 ``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]``
2739 Configure a socket host network backend to share the guest's network
2740 traffic with another QEMU virtual machines using a UDP multicast
2741 socket, effectively making a bus for every QEMU with same multicast
2742 address maddr and port. NOTES:
2744 1. Several QEMU can be running on different hosts and share same bus
2745 (assuming correct multicast setup for these hosts).
2747 2. mcast support is compatible with User Mode Linux (argument
2748 ``ethN=mcast``), see http://user-mode-linux.sf.net.
2750 3. Use ``fd=h`` to specify an already opened UDP multicast socket.
2756 # launch one QEMU instance
2757 |qemu_system| linux.img \
2758 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2759 -netdev socket,id=n1,mcast=230.0.0.1:1234
2760 # launch another QEMU instance on same "bus"
2761 |qemu_system| linux.img \
2762 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
2763 -netdev socket,id=n2,mcast=230.0.0.1:1234
2764 # launch yet another QEMU instance on same "bus"
2765 |qemu_system| linux.img \
2766 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \
2767 -netdev socket,id=n3,mcast=230.0.0.1:1234
2769 Example (User Mode Linux compat.):
2773 # launch QEMU instance (note mcast address selected is UML's default)
2774 |qemu_system| linux.img \
2775 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2776 -netdev socket,id=n1,mcast=239.192.168.1:1102
2778 /path/to/linux ubd0=/path/to/root_fs eth0=mcast
2780 Example (send packets from host's 1.2.3.4):
2784 |qemu_system| linux.img \
2785 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2786 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
2788 ``-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]``
2789 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
2790 is a popular protocol to transport Ethernet (and other Layer 2) data
2791 frames between two systems. It is present in routers, firewalls and
2792 the Linux kernel (from version 3.3 onwards).
2794 This transport allows a VM to communicate to another VM, router or
2798 source address (mandatory)
2801 destination address (mandatory)
2804 select udp encapsulation (default is ip).
2810 destination udp port.
2813 force v6, otherwise defaults to v4.
2815 ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
2816 Cookies are a weak form of security in the l2tpv3 specification.
2817 Their function is mostly to prevent misconfiguration. By default
2821 Set cookie size to 64 bit instead of the default 32
2824 Force a 'cut-down' L2TPv3 with no counter as in
2825 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
2828 Work around broken counter handling in peer. This may also help
2829 on networks which have packet reorder.
2832 Add an extra offset between header and data
2834 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to
2835 the bridge br-lan on the remote Linux host 1.2.3.4:
2839 # Setup tunnel on linux host using raw ip as encapsulation
2841 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \
2842 encap udp udp_sport 16384 udp_dport 16384
2843 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \
2844 0xFFFFFFFF peer_session_id 0xFFFFFFFF
2845 ifconfig vmtunnel0 mtu 1500
2846 ifconfig vmtunnel0 up
2847 brctl addif br-lan vmtunnel0
2851 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
2853 |qemu_system| linux.img -device e1000,netdev=n1 \
2854 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
2856 ``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
2857 Configure VDE backend to connect to PORT n of a vde switch running
2858 on host and listening for incoming connections on socketpath. Use
2859 GROUP groupname and MODE octalmode to change default ownership and
2860 permissions for communication port. This option is only available if
2861 QEMU has been compiled with vde support enabled.
2868 vde_switch -F -sock /tmp/myswitch
2869 # launch QEMU instance
2870 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch
2872 ``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
2873 Establish a vhost-user netdev, backed by a chardev id. The chardev
2874 should be a unix domain socket backed one. The vhost-user uses a
2875 specifically defined protocol to pass vhost ioctl replacement
2876 messages to an application on the other end of the socket. On
2877 non-MSIX guests, the feature can be forced with vhostforce. Use
2878 'queues=n' to specify the number of queues to be created for
2879 multiqueue vhost-user.
2885 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
2886 -numa node,memdev=mem \
2887 -chardev socket,id=chr0,path=/path/to/socket \
2888 -netdev type=vhost-user,id=net0,chardev=chr0 \
2889 -device virtio-net-pci,netdev=net0
2891 ``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
2892 Create a hub port on the emulated hub with ID hubid.
2894 The hubport netdev lets you connect a NIC to a QEMU emulated hub
2895 instead of a single netdev. Alternatively, you can also connect the
2896 hubport to another netdev with ID nd by using the ``netdev=nd``
2899 ``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
2900 Legacy option to configure or create an on-board (or machine
2901 default) Network Interface Card(NIC) and connect it either to the
2902 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
2903 If model is omitted, then the default NIC model associated with the
2904 machine type is used. Note that the default NIC model may change in
2905 future QEMU releases, so it is highly recommended to always specify
2906 a model. Optionally, the MAC address can be changed to mac, the
2907 device address set to addr (PCI cards only), and a name can be
2908 assigned for use in monitor commands. Optionally, for PCI cards, you
2909 can specify the number v of MSI-X vectors that the card should have;
2910 this option currently only affects virtio cards; set v = 0 to
2911 disable MSI-X. If no ``-net`` option is specified, a single NIC is
2912 created. QEMU can emulate several different models of network card.
2913 Use ``-net nic,model=help`` for a list of available devices for your
2916 ``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
2917 Configure a host network backend (with the options corresponding to
2918 the same ``-netdev`` option) and connect it to the emulated hub 0
2919 (the default hub). Use name to specify the name of the hub port.
2924 DEFHEADING(Character device options:)
2926 DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
2928 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2929 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n"
2930 " [,server][,nowait][,telnet][,websocket][,reconnect=seconds][,mux=on|off]\n"
2931 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
2932 "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,websocket][,reconnect=seconds]\n"
2933 " [,mux=on|off][,logfile=PATH][,logappend=on|off] (unix)\n"
2934 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
2935 " [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n"
2936 " [,logfile=PATH][,logappend=on|off]\n"
2937 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2938 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
2939 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2940 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
2941 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2942 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2944 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2945 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2947 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2948 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
2950 #ifdef CONFIG_BRLAPI
2951 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2953 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
2954 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
2955 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2956 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2958 #if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
2959 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2960 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2962 #if defined(CONFIG_SPICE)
2963 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
2964 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
2970 The general form of a character device option is:
2972 ``-chardev backend,id=id[,mux=on|off][,options]``
2973 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
2974 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
2975 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``,
2976 ``spicevmc``, ``spiceport``. The specific backend will determine the
2979 Use ``-chardev help`` to print all available chardev backend types.
2981 All devices must have an id, which can be any string up to 127
2982 characters long. It is used to uniquely identify this device in
2983 other command line directives.
2985 A character device may be used in multiplexing mode by multiple
2986 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
2987 a "1:N" device, and here the "1" end is your specified chardev
2988 backend, and the "N" end is the various parts of QEMU that can talk
2989 to a chardev. If you create a chardev with ``id=myid`` and
2990 ``mux=on``, QEMU will create a multiplexer with your specified ID,
2991 and you can then configure multiple front ends to use that chardev
2992 ID for their input/output. Up to four different front ends can be
2993 connected to a single multiplexed chardev. (Without multiplexing
2994 enabled, a chardev can only be used by a single front end.) For
2995 instance you could use this to allow a single stdio chardev to be
2996 used by two serial ports and the QEMU monitor:
3000 -chardev stdio,mux=on,id=char0 \
3001 -mon chardev=char0,mode=readline \
3002 -serial chardev:char0 \
3003 -serial chardev:char0
3005 You can have more than one multiplexer in a system configuration;
3006 for instance you could have a TCP port multiplexed between UART 0
3007 and UART 1, and stdio multiplexed between the QEMU monitor and a
3012 -chardev stdio,mux=on,id=char0 \
3013 -mon chardev=char0,mode=readline \
3014 -parallel chardev:char0 \
3015 -chardev tcp,...,mux=on,id=char1 \
3016 -serial chardev:char1 \
3017 -serial chardev:char1
3019 When you're using a multiplexed character device, some escape
3020 sequences are interpreted in the input. See :ref:`mux_005fkeys`.
3022 Note that some other command line options may implicitly create
3023 multiplexed character backends; for instance ``-serial mon:stdio``
3024 creates a multiplexed stdio backend connected to the serial port and
3025 the QEMU monitor, and ``-nographic`` also multiplexes the console
3026 and the monitor to stdio.
3028 There is currently no support for multiplexing in the other
3029 direction (where a single QEMU front end takes input and output from
3032 Every backend supports the ``logfile`` option, which supplies the
3033 path to a file to record all data transmitted via the backend. The
3034 ``logappend`` option controls whether the log file will be truncated
3035 or appended to when opened.
3037 The available backends are:
3039 ``-chardev null,id=id``
3040 A void device. This device will not emit any data, and will drop any
3041 data it receives. The null backend does not take any options.
3043 ``-chardev socket,id=id[,TCP options or unix options][,server][,nowait][,telnet][,websocket][,reconnect=seconds][,tls-creds=id][,tls-authz=id]``
3044 Create a two-way stream socket, which can be either a TCP or a unix
3045 socket. A unix socket will be created if ``path`` is specified.
3046 Behaviour is undefined if TCP options are specified for a unix
3049 ``server`` specifies that the socket shall be a listening socket.
3051 ``nowait`` specifies that QEMU should not block waiting for a client
3052 to connect to a listening socket.
3054 ``telnet`` specifies that traffic on the socket should interpret
3055 telnet escape sequences.
3057 ``websocket`` specifies that the socket uses WebSocket protocol for
3060 ``reconnect`` sets the timeout for reconnecting on non-server
3061 sockets when the remote end goes away. qemu will delay this many
3062 seconds and then attempt to reconnect. Zero disables reconnecting,
3065 ``tls-creds`` requests enablement of the TLS protocol for
3066 encryption, and specifies the id of the TLS credentials to use for
3067 the handshake. The credentials must be previously created with the
3068 ``-object tls-creds`` argument.
3070 ``tls-auth`` provides the ID of the QAuthZ authorization object
3071 against which the client's x509 distinguished name will be
3072 validated. This object is only resolved at time of use, so can be
3073 deleted and recreated on the fly while the chardev server is active.
3074 If missing, it will default to denying access.
3076 TCP and unix socket options are given below:
3078 ``TCP options: port=port[,host=host][,to=to][,ipv4][,ipv6][,nodelay]``
3079 ``host`` for a listening socket specifies the local address to
3080 be bound. For a connecting socket species the remote host to
3081 connect to. ``host`` is optional for listening sockets. If not
3082 specified it defaults to ``0.0.0.0``.
3084 ``port`` for a listening socket specifies the local port to be
3085 bound. For a connecting socket specifies the port on the remote
3086 host to connect to. ``port`` can be given as either a port
3087 number or a service name. ``port`` is required.
3089 ``to`` is only relevant to listening sockets. If it is
3090 specified, and ``port`` cannot be bound, QEMU will attempt to
3091 bind to subsequent ports up to and including ``to`` until it
3092 succeeds. ``to`` must be specified as a port number.
3094 ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be
3095 used. If neither is specified the socket may use either
3098 ``nodelay`` disables the Nagle algorithm.
3100 ``unix options: path=path``
3101 ``path`` specifies the local path of the unix socket. ``path``
3104 ``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4][,ipv6]``
3105 Sends all traffic from the guest to a remote host over UDP.
3107 ``host`` specifies the remote host to connect to. If not specified
3108 it defaults to ``localhost``.
3110 ``port`` specifies the port on the remote host to connect to.
3111 ``port`` is required.
3113 ``localaddr`` specifies the local address to bind to. If not
3114 specified it defaults to ``0.0.0.0``.
3116 ``localport`` specifies the local port to bind to. If not specified
3117 any available local port will be used.
3119 ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be used.
3120 If neither is specified the device may use either protocol.
3122 ``-chardev msmouse,id=id``
3123 Forward QEMU's emulated msmouse events to the guest. ``msmouse``
3124 does not take any options.
3126 ``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]``
3127 Connect to a QEMU text console. ``vc`` may optionally be given a
3130 ``width`` and ``height`` specify the width and height respectively
3131 of the console, in pixels.
3133 ``cols`` and ``rows`` specify that the console be sized to fit a
3134 text console with the given dimensions.
3136 ``-chardev ringbuf,id=id[,size=size]``
3137 Create a ring buffer with fixed size ``size``. size must be a power
3138 of two and defaults to ``64K``.
3140 ``-chardev file,id=id,path=path``
3141 Log all traffic received from the guest to a file.
3143 ``path`` specifies the path of the file to be opened. This file will
3144 be created if it does not already exist, and overwritten if it does.
3145 ``path`` is required.
3147 ``-chardev pipe,id=id,path=path``
3148 Create a two-way connection to the guest. The behaviour differs
3149 slightly between Windows hosts and other hosts:
3151 On Windows, a single duplex pipe will be created at
3154 On other hosts, 2 pipes will be created called ``path.in`` and
3155 ``path.out``. Data written to ``path.in`` will be received by the
3156 guest. Data written by the guest can be read from ``path.out``. QEMU
3157 will not create these fifos, and requires them to be present.
3159 ``path`` forms part of the pipe path as described above. ``path`` is
3162 ``-chardev console,id=id``
3163 Send traffic from the guest to QEMU's standard output. ``console``
3164 does not take any options.
3166 ``console`` is only available on Windows hosts.
3168 ``-chardev serial,id=id,path=path``
3169 Send traffic from the guest to a serial device on the host.
3171 On Unix hosts serial will actually accept any tty device, not only
3174 ``path`` specifies the name of the serial device to open.
3176 ``-chardev pty,id=id``
3177 Create a new pseudo-terminal on the host and connect to it. ``pty``
3178 does not take any options.
3180 ``pty`` is not available on Windows hosts.
3182 ``-chardev stdio,id=id[,signal=on|off]``
3183 Connect to standard input and standard output of the QEMU process.
3185 ``signal`` controls if signals are enabled on the terminal, that
3186 includes exiting QEMU with the key sequence Control-c. This option
3187 is enabled by default, use ``signal=off`` to disable it.
3189 ``-chardev braille,id=id``
3190 Connect to a local BrlAPI server. ``braille`` does not take any
3193 ``-chardev tty,id=id,path=path``
3194 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD
3195 and DragonFlyBSD hosts. It is an alias for ``serial``.
3197 ``path`` specifies the path to the tty. ``path`` is required.
3199 ``-chardev parallel,id=id,path=path``
3201 ``-chardev parport,id=id,path=path``
3202 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
3205 Connect to a local parallel port.
3207 ``path`` specifies the path to the parallel port device. ``path`` is
3210 ``-chardev spicevmc,id=id,debug=debug,name=name``
3211 ``spicevmc`` is only available when spice support is built in.
3213 ``debug`` debug level for spicevmc
3215 ``name`` name of spice channel to connect to
3217 Connect to a spice virtual machine channel, such as vdiport.
3219 ``-chardev spiceport,id=id,debug=debug,name=name``
3220 ``spiceport`` is only available when spice support is built in.
3222 ``debug`` debug level for spicevmc
3224 ``name`` name of spice port to connect to
3226 Connect to a spice port, allowing a Spice client to handle the
3227 traffic identified by a name (preferably a fqdn).
3233 DEFHEADING(TPM device options:)
3235 DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3236 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3237 " use path to provide path to a character device; default is /dev/tpm0\n"
3238 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
3239 " not provided it will be searched for in /sys/class/misc/tpm?/device\n"
3240 "-tpmdev emulator,id=id,chardev=dev\n"
3241 " configure the TPM device using chardev backend\n",
3244 The general form of a TPM device option is:
3246 ``-tpmdev backend,id=id[,options]``
3247 The specific backend type will determine the applicable options. The
3248 ``-tpmdev`` option creates the TPM backend and requires a
3249 ``-device`` option that specifies the TPM frontend interface model.
3251 Use ``-tpmdev help`` to print all available TPM backend types.
3253 The available backends are:
3255 ``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
3256 (Linux-host only) Enable access to the host's TPM using the
3259 ``path`` specifies the path to the host's TPM device, i.e., on a
3260 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
3261 default ``/dev/tpm0`` is used.
3263 ``cancel-path`` specifies the path to the host TPM device's sysfs
3264 entry allowing for cancellation of an ongoing TPM command.
3265 ``cancel-path`` is optional and by default QEMU will search for the
3268 Some notes about using the host's TPM with the passthrough driver:
3270 The TPM device accessed by the passthrough driver must not be used
3271 by any other application on the host.
3273 Since the host's firmware (BIOS/UEFI) has already initialized the
3274 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
3275 the TPM again and may therefore not show a TPM-specific menu that
3276 would otherwise allow the user to configure the TPM, e.g., allow the
3277 user to enable/disable or activate/deactivate the TPM. Further, if
3278 TPM ownership is released from within a VM then the host's TPM will
3279 get disabled and deactivated. To enable and activate the TPM again
3280 afterwards, the host has to be rebooted and the user is required to
3281 enter the firmware's menu to enable and activate the TPM. If the TPM
3282 is left disabled and/or deactivated most TPM commands will fail.
3284 To create a passthrough TPM use the following two options:
3288 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3290 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
3291 ``tpmdev=tpm0`` in the device option.
3293 ``-tpmdev emulator,id=id,chardev=dev``
3294 (Linux-host only) Enable access to a TPM emulator using Unix domain
3295 socket based chardev backend.
3297 ``chardev`` specifies the unique ID of a character device backend
3298 that provides connection to the software TPM server.
3300 To create a TPM emulator backend device with chardev socket backend:
3304 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3311 DEFHEADING(Linux/Multiboot boot specific:)
3313 When using these options, you can use a given Linux or Multiboot kernel
3314 without installing it in the disk image. It can be useful for easier
3315 testing of various kernels.
3320 DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
3321 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
3324 Use bzImage as kernel image. The kernel can be either a Linux kernel
3325 or in multiboot format.
3328 DEF("append", HAS_ARG, QEMU_OPTION_append, \
3329 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
3332 Use cmdline as kernel command line
3335 DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
3336 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
3339 Use file as initial ram disk.
3341 ``-initrd "file1 arg=foo,file2"``
3342 This syntax is only available with multiboot.
3344 Use file1 and file2 as modules and pass arg=foo as parameter to the
3348 DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
3349 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL)
3352 Use file as a device tree binary (dtb) image and pass it to the
3358 DEFHEADING(Debug/Expert options:)
3360 DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
3361 "-fw_cfg [name=]<name>,file=<file>\n"
3362 " add named fw_cfg entry with contents from file\n"
3363 "-fw_cfg [name=]<name>,string=<str>\n"
3364 " add named fw_cfg entry with contents from string\n",
3367 ``-fw_cfg [name=]name,file=file``
3368 Add named fw\_cfg entry with contents from file file.
3370 ``-fw_cfg [name=]name,string=str``
3371 Add named fw\_cfg entry with contents from string str.
3373 The terminating NUL character of the contents of str will not be
3374 included as part of the fw\_cfg item data. To insert contents with
3375 embedded NUL characters, you have to use the file parameter.
3377 The fw\_cfg entries are passed by QEMU through to the guest.
3383 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
3385 creates an fw\_cfg entry named opt/com.mycompany/blob with contents
3386 from ./my\_blob.bin.
3389 DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
3390 "-serial dev redirect the serial port to char device 'dev'\n",
3394 Redirect the virtual serial port to host character device dev. The
3395 default device is ``vc`` in graphical mode and ``stdio`` in non
3398 This option can be used several times to simulate up to 4 serial
3401 Use ``-serial none`` to disable all serial ports.
3403 Available character devices are:
3406 Virtual console. Optionally, a width and height can be given in
3413 It is also possible to specify width or height in characters:
3420 [Linux only] Pseudo TTY (a new PTY is automatically allocated)
3423 No device is allocated.
3429 Use a named character device defined with the ``-chardev``
3433 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
3434 port parameters are set according to the emulated ones.
3437 [Linux only, parallel port only] Use host parallel port N.
3438 Currently SPP and EPP parallel port features can be used.
3441 Write output to filename. No character can be read.
3444 [Unix only] standard input/output
3450 [Windows only] Use host serial port n
3452 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
3453 This implements UDP Net Console. When remote\_host or src\_ip
3454 are not specified they default to ``0.0.0.0``. When not using a
3455 specified src\_port a random port is automatically chosen.
3457 If you just want a simple readonly console you can use
3458 ``netcat`` or ``nc``, by starting QEMU with:
3459 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
3460 QEMU writes something to that port it will appear in the
3463 If you plan to send characters back via netconsole or you want
3464 to stop and start QEMU a lot of times, you should have QEMU use
3465 the same source port each time by using something like ``-serial
3466 udp::4555@:4556`` to QEMU. Another approach is to use a patched
3467 version of netcat which can listen to a TCP port and send and
3468 receive characters via udp. If you have a patched version of
3469 netcat which activates telnet remote echo and single char
3470 transfer, then you can use the following options to set up a
3471 netcat redirector to allow telnet on port 5555 to access the
3475 -serial udp::4555@:4556
3478 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
3483 ``tcp:[host]:port[,server][,nowait][,nodelay][,reconnect=seconds]``
3484 The TCP Net Console has two modes of operation. It can send the
3485 serial I/O to a location or wait for a connection from a
3486 location. By default the TCP Net Console is sent to host at the
3487 port. If you use the server option QEMU will wait for a client
3488 socket application to connect to the port before continuing,
3489 unless the ``nowait`` option was specified. The ``nodelay``
3490 option disables the Nagle buffering algorithm. The ``reconnect``
3491 option only applies if noserver is set, if the connection goes
3492 down it will attempt to reconnect at the given interval. If host
3493 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a
3494 time is accepted. You can use ``telnet`` to connect to the
3495 corresponding character device.
3497 ``Example to send tcp console to 192.168.0.2 port 4444``
3498 -serial tcp:192.168.0.2:4444
3500 ``Example to listen and wait on port 4444 for connection``
3501 -serial tcp::4444,server
3503 ``Example to not wait and listen on ip 192.168.0.100 port 4444``
3504 -serial tcp:192.168.0.100:4444,server,nowait
3506 ``telnet:host:port[,server][,nowait][,nodelay]``
3507 The telnet protocol is used instead of raw tcp sockets. The
3508 options work the same as if you had specified ``-serial tcp``.
3509 The difference is that the port acts like a telnet server or
3510 client using telnet option negotiation. This will also allow you
3511 to send the MAGIC\_SYSRQ sequence if you use a telnet that
3512 supports sending the break sequence. Typically in unix telnet
3513 you do it with Control-] and then type "send break" followed by
3514 pressing the enter key.
3516 ``websocket:host:port,server[,nowait][,nodelay]``
3517 The WebSocket protocol is used instead of raw tcp socket. The
3518 port acts as a WebSocket server. Client mode is not supported.
3520 ``unix:path[,server][,nowait][,reconnect=seconds]``
3521 A unix domain socket is used instead of a tcp socket. The option
3522 works the same as if you had specified ``-serial tcp`` except
3523 the unix domain socket path is used for connections.
3526 This is a special option to allow the monitor to be multiplexed
3527 onto another serial port. The monitor is accessed with key
3528 sequence of Control-a and then pressing c. dev\_string should be
3529 any one of the serial devices specified above. An example to
3530 multiplex the monitor onto a telnet server listening on port
3533 ``-serial mon:telnet::4444,server,nowait``
3535 When the monitor is multiplexed to stdio in this way, Ctrl+C
3536 will not terminate QEMU any more but will be passed to the guest
3540 Braille device. This will use BrlAPI to display the braille
3541 output on a real or fake device.
3544 Three button serial mouse. Configure the guest to use Microsoft
3548 DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
3549 "-parallel dev redirect the parallel port to char device 'dev'\n",
3553 Redirect the virtual parallel port to host device dev (same devices
3554 as the serial port). On Linux hosts, ``/dev/parportN`` can be used
3555 to use hardware devices connected on the corresponding host parallel
3558 This option can be used several times to simulate up to 3 parallel
3561 Use ``-parallel none`` to disable all parallel ports.
3564 DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
3565 "-monitor dev redirect the monitor to char device 'dev'\n",
3569 Redirect the monitor to host device dev (same devices as the serial
3570 port). The default device is ``vc`` in graphical mode and ``stdio``
3571 in non graphical mode. Use ``-monitor none`` to disable the default
3574 DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
3575 "-qmp dev like -monitor but opens in 'control' mode\n",
3579 Like -monitor but opens in 'control' mode.
3581 DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
3582 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
3586 Like -qmp but uses pretty JSON formatting.
3589 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
3590 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
3592 ``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
3593 Setup monitor on chardev name. ``pretty`` turns on JSON pretty
3594 printing easing human reading and debugging.
3597 DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
3598 "-debugcon dev redirect the debug console to char device 'dev'\n",
3602 Redirect the debug console to host device dev (same devices as the
3603 serial port). The debug console is an I/O port which is typically
3604 port 0xe9; writing to that I/O port sends output to this device. The
3605 default device is ``vc`` in graphical mode and ``stdio`` in non
3609 DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
3610 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL)
3613 Store the QEMU process PID in file. It is useful if you launch QEMU
3617 DEF("singlestep", 0, QEMU_OPTION_singlestep, \
3618 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL)
3621 Run the emulation in single step mode.
3624 DEF("preconfig", 0, QEMU_OPTION_preconfig, \
3625 "--preconfig pause QEMU before machine is initialized (experimental)\n",
3629 Pause QEMU for interactive configuration before the machine is
3630 created, which allows querying and configuring properties that will
3631 affect machine initialization. Use QMP command 'x-exit-preconfig' to
3632 exit the preconfig state and move to the next state (i.e. run guest
3633 if -S isn't used or pause the second time if -S is used). This
3634 option is experimental.
3637 DEF("S", 0, QEMU_OPTION_S, \
3638 "-S freeze CPU at startup (use 'c' to start execution)\n",
3642 Do not start CPU at startup (you must type 'c' in the monitor).
3645 DEF("realtime", HAS_ARG, QEMU_OPTION_realtime,
3646 "-realtime [mlock=on|off]\n"
3647 " run qemu with realtime features\n"
3648 " mlock=on|off controls mlock support (default: on)\n",
3651 ``-realtime mlock=on|off``
3652 Run qemu with realtime features. mlocking qemu and guest memory can
3653 be enabled via ``mlock=on`` (enabled by default).
3656 DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
3657 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
3658 " run qemu with overcommit hints\n"
3659 " mem-lock=on|off controls memory lock support (default: off)\n"
3660 " cpu-pm=on|off controls cpu power management (default: off)\n",
3663 ``-overcommit mem-lock=on|off``
3665 ``-overcommit cpu-pm=on|off``
3666 Run qemu with hints about host resource overcommit. The default is
3667 to assume that host overcommits all resources.
3669 Locking qemu and guest memory can be enabled via ``mem-lock=on``
3670 (disabled by default). This works when host memory is not
3671 overcommitted and reduces the worst-case latency for guest. This is
3672 equivalent to ``realtime``.
3674 Guest ability to manage power state of host cpus (increasing latency
3675 for other processes on the same host cpu, but decreasing latency for
3676 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
3677 works best when host CPU is not overcommitted. When used, host
3678 estimates of CPU cycle and power utilization will be incorrect, not
3679 taking into account guest idle time.
3682 DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
3683 "-gdb dev wait for gdb connection on 'dev'\n", QEMU_ARCH_ALL)
3686 Wait for gdb connection on device dev (see
3687 :ref:`gdb_005fusage`). Typical connections will likely be
3688 TCP-based, but also UDP, pseudo TTY, or even stdio are reasonable
3689 use case. The latter is allowing to start QEMU from within gdb and
3690 establish the connection via a pipe:
3694 (gdb) target remote | exec |qemu_system| -gdb stdio ...
3697 DEF("s", 0, QEMU_OPTION_s, \
3698 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
3702 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
3703 (see :ref:`gdb_005fusage`).
3706 DEF("d", HAS_ARG, QEMU_OPTION_d, \
3707 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n",
3711 Enable logging of specified items. Use '-d help' for a list of log
3715 DEF("D", HAS_ARG, QEMU_OPTION_D, \
3716 "-D logfile output log to logfile (default stderr)\n",
3720 Output log in logfile instead of to stderr
3723 DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
3724 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
3727 ``-dfilter range1[,...]``
3728 Filter debug output to that relevant to a range of target addresses.
3729 The filter spec can be either start+size, start-size or start..end
3730 where start end and size are the addresses and sizes required. For
3735 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
3737 Will dump output for any code in the 0x1000 sized block starting at
3738 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
3739 another 0x1000 sized block starting at 0xffffffc00005f000.
3742 DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
3743 "-seed number seed the pseudo-random number generator\n",
3747 Force the guest to use a deterministic pseudo-random number
3748 generator, seeded with number. This does not affect crypto routines
3752 DEF("L", HAS_ARG, QEMU_OPTION_L, \
3753 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n",
3757 Set the directory for the BIOS, VGA BIOS and keymaps.
3759 To list all the data directories, use ``-L help``.
3762 DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
3763 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL)
3766 Set the filename for the BIOS.
3769 DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
3770 "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ALL)
3773 Enable KVM full virtualization support. This option is only
3774 available if KVM support is enabled when compiling.
3777 DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
3778 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL)
3779 DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
3780 "-xen-attach attach to existing xen domain\n"
3781 " libxl will use this when starting QEMU\n",
3783 DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
3784 "-xen-domid-restrict restrict set of available xen operations\n"
3785 " to specified domain id. (Does not affect\n"
3786 " xenpv machine type).\n",
3790 Specify xen guest domain id (XEN only).
3793 Attach to existing xen domain. libxl will use this when starting
3794 QEMU (XEN only). Restrict set of available xen operations to
3795 specified domain id (XEN only).
3798 DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
3799 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL)
3802 Exit instead of rebooting.
3805 DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
3806 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL)
3809 Don't exit QEMU on guest shutdown, but instead only stop the
3810 emulation. This allows for instance switching to monitor to commit
3811 changes to the disk image.
3814 DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
3815 "-loadvm [tag|id]\n" \
3816 " start right away with a saved state (loadvm in monitor)\n",
3820 Start right away with a saved state (``loadvm`` in monitor)
3824 DEF("daemonize", 0, QEMU_OPTION_daemonize, \
3825 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
3829 Daemonize the QEMU process after initialization. QEMU will not
3830 detach from standard IO until it is ready to receive connections on
3831 any of its devices. This option is a useful way for external
3832 programs to launch QEMU without having to cope with initialization
3836 DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
3837 "-option-rom rom load a file, rom, into the option ROM space\n",
3840 ``-option-rom file``
3841 Load the contents of file as an option ROM. This option is useful to
3842 load things like EtherBoot.
3845 DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
3846 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
3847 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
3851 ``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
3852 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
3853 the current UTC or local time, respectively. ``localtime`` is
3854 required for correct date in MS-DOS or Windows. To start at a
3855 specific point in time, provide datetime in the format
3856 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.
3858 By default the RTC is driven by the host system time. This allows
3859 using of the RTC as accurate reference clock inside the guest,
3860 specifically if the host time is smoothly following an accurate
3861 external reference clock, e.g. via NTP. If you want to isolate the
3862 guest time from the host, you can set ``clock`` to ``rt`` instead,
3863 which provides a host monotonic clock if host support it. To even
3864 prevent the RTC from progressing during suspension, you can set
3865 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
3866 recommended especially in icount mode in order to preserve
3867 determinism; however, note that in icount mode the speed of the
3868 virtual clock is variable and can in general differ from the host
3871 Enable ``driftfix`` (i386 targets only) if you experience time drift
3872 problems, specifically with Windows' ACPI HAL. This option will try
3873 to figure out how many timer interrupts were not processed by the
3874 Windows guest and will re-inject them.
3877 DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
3878 "-icount [shift=N|auto][,align=on|off][,sleep=on|off,rr=record|replay,rrfile=<filename>,rrsnapshot=<snapshot>]\n" \
3879 " enable virtual instruction counter with 2^N clock ticks per\n" \
3880 " instruction, enable aligning the host and virtual clocks\n" \
3881 " or disable real time cpu sleeping\n", QEMU_ARCH_ALL)
3883 ``-icount [shift=N|auto][,rr=record|replay,rrfile=filename,rrsnapshot=snapshot]``
3884 Enable virtual instruction counter. The virtual cpu will execute one
3885 instruction every 2^N ns of virtual time. If ``auto`` is specified
3886 then the virtual cpu speed will be automatically adjusted to keep
3887 virtual time within a few seconds of real time.
3889 When the virtual cpu is sleeping, the virtual time will advance at
3890 default speed unless ``sleep=on|off`` is specified. With
3891 ``sleep=on|off``, the virtual time will jump to the next timer
3892 deadline instantly whenever the virtual cpu goes to sleep mode and
3893 will not advance if no timer is enabled. This behavior give
3894 deterministic execution times from the guest point of view.
3896 Note that while this option can give deterministic behavior, it does
3897 not provide cycle accurate emulation. Modern CPUs contain
3898 superscalar out of order cores with complex cache hierarchies. The
3899 number of instructions executed often has little or no correlation
3900 with actual performance.
3902 ``align=on`` will activate the delay algorithm which will try to
3903 synchronise the host clock and the virtual clock. The goal is to
3904 have a guest running at the real frequency imposed by the shift
3905 option. Whenever the guest clock is behind the host clock and if
3906 ``align=on`` is specified then we print a message to the user to
3907 inform about the delay. Currently this option does not work when
3908 ``shift`` is ``auto``. Note: The sync algorithm will work for those
3909 shift values for which the guest clock runs ahead of the host clock.
3910 Typically this happens when the shift value is high (how high
3911 depends on the host machine).
3913 When ``rr`` option is specified deterministic record/replay is
3914 enabled. Replay log is written into filename file in record mode and
3915 read from this file in replay mode.
3917 Option rrsnapshot is used to create new vm snapshot named snapshot
3918 at the start of execution recording. In replay mode this option is
3919 used to load the initial VM state.
3922 DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
3923 "-watchdog model\n" \
3924 " enable virtual hardware watchdog [default=none]\n",
3928 Create a virtual hardware watchdog device. Once enabled (by a guest
3929 action), the watchdog must be periodically polled by an agent inside
3930 the guest or else the guest will be restarted. Choose a model for
3931 which your guest has drivers.
3933 The model is the model of hardware watchdog to emulate. Use
3934 ``-watchdog help`` to list available hardware models. Only one
3935 watchdog can be enabled for a guest.
3937 The following models may be available:
3940 iBASE 700 is a very simple ISA watchdog with a single timer.
3943 Intel 6300ESB I/O controller hub is a much more featureful
3944 PCI-based dual-timer watchdog.
3947 A virtual watchdog for s390x backed by the diagnose 288
3948 hypercall (currently KVM only).
3951 DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
3952 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
3953 " action when watchdog fires [default=reset]\n",
3956 ``-watchdog-action action``
3957 The action controls what QEMU will do when the watchdog timer
3958 expires. The default is ``reset`` (forcefully reset the guest).
3959 Other possible actions are: ``shutdown`` (attempt to gracefully
3960 shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
3961 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
3962 guest), ``debug`` (print a debug message and continue), or ``none``
3965 Note that the ``shutdown`` action requires that the guest responds
3966 to ACPI signals, which it may not be able to do in the sort of
3967 situations where the watchdog would have expired, and thus
3968 ``-watchdog-action shutdown`` is not recommended for production use.
3972 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700``
3976 DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
3977 "-echr chr set terminal escape character instead of ctrl-a\n",
3980 ``-echr numeric_ascii_value``
3981 Change the escape character used for switching to the monitor when
3982 using monitor and serial sharing. The default is ``0x01`` when using
3983 the ``-nographic`` option. ``0x01`` is equal to pressing
3984 ``Control-a``. You can select a different character from the ascii
3985 control keys where 1 through 26 map to Control-a through Control-z.
3986 For instance you could use the either of the following to change the
3987 escape character to Control-t.
3989 ``-echr 0x14``; \ ``-echr 20``
3993 DEF("show-cursor", 0, QEMU_OPTION_show_cursor, \
3994 "-show-cursor show cursor\n", QEMU_ARCH_ALL)
4000 DEF("tb-size", HAS_ARG, QEMU_OPTION_tb_size, \
4001 "-tb-size n set TB size\n", QEMU_ARCH_ALL)
4004 Set TCG translation block cache size. Deprecated, use
4005 '\ ``-accel tcg,tb-size=n``\ ' instead.
4008 DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
4009 "-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]\n" \
4010 "-incoming rdma:host:port[,ipv4][,ipv6]\n" \
4011 "-incoming unix:socketpath\n" \
4012 " prepare for incoming migration, listen on\n" \
4013 " specified protocol and socket address\n" \
4014 "-incoming fd:fd\n" \
4015 "-incoming exec:cmdline\n" \
4016 " accept incoming migration on given file descriptor\n" \
4017 " or from given external command\n" \
4018 "-incoming defer\n" \
4019 " wait for the URI to be specified via migrate_incoming\n",
4022 ``-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]``
4024 ``-incoming rdma:host:port[,ipv4][,ipv6]``
4025 Prepare for incoming migration, listen on a given tcp port.
4027 ``-incoming unix:socketpath``
4028 Prepare for incoming migration, listen on a given unix socket.
4031 Accept incoming migration from a given filedescriptor.
4033 ``-incoming exec:cmdline``
4034 Accept incoming migration as an output from specified external
4038 Wait for the URI to be specified via migrate\_incoming. The monitor
4039 can be used to change settings (such as migration parameters) prior
4040 to issuing the migrate\_incoming to allow the migration to begin.
4043 DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
4044 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL)
4046 ``-only-migratable``
4047 Only allow migratable devices. Devices will not be allowed to enter
4048 an unmigratable state.
4051 DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
4052 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL)
4055 Don't create default devices. Normally, QEMU sets the default
4056 devices like serial port, parallel port, virtual console, monitor
4057 device, VGA adapter, floppy and CD-ROM drive and others. The
4058 ``-nodefaults`` option will disable all those default devices.
4062 DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
4063 "-chroot dir chroot to dir just before starting the VM\n",
4068 Immediately before starting guest execution, chroot to the specified
4069 directory. Especially useful in combination with -runas.
4073 DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
4074 "-runas user change to user id user just before starting the VM\n" \
4075 " user can be numeric uid:gid instead\n",
4080 Immediately before starting guest execution, drop root privileges,
4081 switching to the specified user.
4084 DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
4085 "-prom-env variable=value\n"
4086 " set OpenBIOS nvram variables\n",
4087 QEMU_ARCH_PPC | QEMU_ARCH_SPARC)
4089 ``-prom-env variable=value``
4090 Set OpenBIOS nvram variable to given value (PPC, SPARC only).
4094 qemu-system-sparc -prom-env 'auto-boot?=false' \
4095 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single'
4099 qemu-system-ppc -prom-env 'auto-boot?=false' \
4100 -prom-env 'boot-device=hd:2,\yaboot' \
4101 -prom-env 'boot-args=conf=hd:2,\yaboot.conf'
4103 DEF("semihosting", 0, QEMU_OPTION_semihosting,
4104 "-semihosting semihosting mode\n",
4105 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4106 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
4109 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only).
4111 Note that this allows guest direct access to the host filesystem, so
4112 should only be used with a trusted guest OS.
4114 See the -semihosting-config option documentation for further
4115 information about the facilities this enables.
4117 DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
4118 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
4119 " semihosting configuration\n",
4120 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4121 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
4123 ``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]``
4124 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II
4127 Note that this allows guest direct access to the host filesystem, so
4128 should only be used with a trusted guest OS.
4130 On Arm this implements the standard semihosting API, version 2.0.
4132 On M68K this implements the "ColdFire GDB" interface used by
4135 Xtensa semihosting provides basic file IO calls, such as
4136 open/read/write/seek/select. Tensilica baremetal libc for ISS and
4137 linux platform "sim" use this interface.
4139 ``target=native|gdb|auto``
4140 Defines where the semihosting calls will be addressed, to QEMU
4141 (``native``) or to GDB (``gdb``). The default is ``auto``, which
4142 means ``gdb`` during debug sessions and ``native`` otherwise.
4145 Send the output to a chardev backend output for native or auto
4146 output when not in gdb
4148 ``arg=str1,arg=str2,...``
4149 Allows the user to pass input arguments, and can be used
4150 multiple times to build up a list. The old-style
4151 ``-kernel``/``-append`` method of passing a command line is
4152 still supported for backward compatibility. If both the
4153 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are
4154 specified, the former is passed to semihosting as it always
4157 DEF("old-param", 0, QEMU_OPTION_old_param,
4158 "-old-param old param mode\n", QEMU_ARCH_ARM)
4161 Old param mode (ARM only).
4164 DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
4165 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4166 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4167 " Enable seccomp mode 2 system call filter (default 'off').\n" \
4168 " use 'obsolete' to allow obsolete system calls that are provided\n" \
4169 " by the kernel, but typically no longer used by modern\n" \
4170 " C library implementations.\n" \
4171 " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
4172 " its privileges by blacklisting all set*uid|gid system calls.\n" \
4173 " The value 'children' will deny set*uid|gid system calls for\n" \
4174 " main QEMU process but will allow forks and execves to run unprivileged\n" \
4175 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4176 " blacklisting *fork and execve\n" \
4177 " use 'resourcecontrol' to disable process affinity and schedular priority\n",
4180 ``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]``
4181 Enable Seccomp mode 2 system call filter. 'on' will enable syscall
4182 filtering and 'off' will disable it. The default is 'off'.
4185 Enable Obsolete system calls
4187 ``elevateprivileges=string``
4188 Disable set\*uid\|gid system calls
4191 Disable \*fork and execve
4193 ``resourcecontrol=string``
4194 Disable process affinity and schedular priority
4197 DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
4198 "-readconfig <file>\n", QEMU_ARCH_ALL)
4200 ``-readconfig file``
4201 Read device configuration from file. This approach is useful when
4202 you want to spawn QEMU process with many command line options but
4203 you don't want to exceed the command line character limit.
4205 DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
4206 "-writeconfig <file>\n"
4207 " read/write config file\n", QEMU_ARCH_ALL)
4209 ``-writeconfig file``
4210 Write device configuration to file. The file can be either filename
4211 to save command line and device configuration into file or dash
4212 ``-``) character to print the output to stdout. This can be later
4213 used as input file for ``-readconfig`` option.
4216 DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4218 " do not load default user-provided config files at startup\n",
4222 The ``-no-user-config`` option makes QEMU not load any of the
4223 user-provided config files on sysconfdir.
4226 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4227 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4228 " specify tracing options\n",
4231 ``-trace [[enable=]pattern][,events=file][,file=file]``
4232 .. include:: ../qemu-option-trace.rst.inc
4235 DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4236 "-plugin [file=]<file>[,arg=<string>]\n"
4240 ``-plugin file=file[,arg=string]``
4244 Load the given plugin from a shared library file.
4247 Argument string passed to the plugin. (Can be given multiple
4252 DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4253 DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4256 DEF("enable-fips", 0, QEMU_OPTION_enablefips,
4257 "-enable-fips enable FIPS 140-2 compliance\n",
4262 Enable FIPS 140-2 compliance mode.
4265 HXCOMM Deprecated by -accel tcg
4266 DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386)
4268 DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4269 "-msg timestamp[=on|off]\n"
4270 " control error message format\n"
4271 " timestamp=on enables timestamps (default: off)\n",
4274 ``-msg timestamp[=on|off]``
4275 Control error message format.
4277 ``timestamp=on|off``
4278 Prefix messages with a timestamp. Default is off.
4281 DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
4282 "-dump-vmstate <file>\n"
4283 " Output vmstate information in JSON format to file.\n"
4284 " Use the scripts/vmstate-static-checker.py file to\n"
4285 " check for possible regressions in migration code\n"
4286 " by comparing two such vmstate dumps.\n",
4289 ``-dump-vmstate file``
4290 Dump json-encoded vmstate information for current machine type to
4294 DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
4295 "-enable-sync-profile\n"
4296 " enable synchronization profiling\n",
4299 ``-enable-sync-profile``
4300 Enable synchronization profiling.
4305 DEFHEADING(Generic object creation:)
4307 DEF("object", HAS_ARG, QEMU_OPTION_object,
4308 "-object TYPENAME[,PROP1=VALUE1,...]\n"
4309 " create a new object of type TYPENAME setting properties\n"
4310 " in the order they are specified. Note that the 'id'\n"
4311 " property must be set. These objects are placed in the\n"
4312 " '/objects' path.\n",
4315 ``-object typename[,prop1=value1,...]``
4316 Create a new object of type typename setting properties in the order
4317 they are specified. Note that the 'id' property must be set. These
4318 objects are placed in the '/objects' path.
4320 ``-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``
4321 Creates a memory file backend object, which can be used to back
4322 the guest RAM with huge pages.
4324 The ``id`` parameter is a unique ID that will be used to
4325 reference this memory region when configuring the ``-numa``
4328 The ``size`` option provides the size of the memory region, and
4329 accepts common suffixes, eg ``500M``.
4331 The ``mem-path`` provides the path to either a shared memory or
4332 huge page filesystem mount.
4334 The ``share`` boolean option determines whether the memory
4335 region is marked as private to QEMU, or shared. The latter
4336 allows a co-operating external process to access the QEMU memory
4339 The ``share`` is also required for pvrdma devices due to
4340 limitations in the RDMA API provided by Linux.
4342 Setting share=on might affect the ability to configure NUMA
4343 bindings for the memory backend under some circumstances, see
4344 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
4345 source tree for additional details.
4347 Setting the ``discard-data`` boolean option to on indicates that
4348 file contents can be destroyed when QEMU exits, to avoid
4349 unnecessarily flushing data to the backing file. Note that
4350 ``discard-data`` is only an optimization, and QEMU might not
4351 discard file contents if it aborts unexpectedly or is terminated
4354 The ``merge`` boolean option enables memory merge, also known as
4355 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
4356 the pages for memory deduplication.
4358 Setting the ``dump`` boolean option to off excludes the memory
4359 from core dumps. This feature is also known as MADV\_DONTDUMP.
4361 The ``prealloc`` boolean option enables memory preallocation.
4363 The ``host-nodes`` option binds the memory range to a list of
4366 The ``policy`` option sets the NUMA policy to one of the
4373 prefer the given host node list for allocation
4376 restrict memory allocation to the given host node list
4379 interleave memory allocations across the given host node
4382 The ``align`` option specifies the base address alignment when
4383 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
4384 ``2M``. Some backend store specified by ``mem-path`` requires an
4385 alignment different than the default one used by QEMU, eg the
4386 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
4387 such cases, users can specify the required alignment via this
4390 The ``pmem`` option specifies whether the backing file specified
4391 by ``mem-path`` is in host persistent memory that can be
4392 accessed using the SNIA NVM programming model (e.g. Intel
4393 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary
4394 operations to guarantee the persistence of its own writes to
4395 ``mem-path`` (e.g. in vNVDIMM label emulation and live
4396 migration). Also, we will map the backend-file with MAP\_SYNC
4397 flag, which ensures the file metadata is in sync for
4398 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
4399 requires support from both the host kernel (since Linux kernel
4400 4.15) and the filesystem of ``mem-path`` mounted with DAX
4403 ``-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``
4404 Creates a memory backend object, which can be used to back the
4405 guest RAM. Memory backend objects offer more control than the
4406 ``-m`` option that is traditionally used to define guest RAM.
4407 Please refer to ``memory-backend-file`` for a description of the
4410 ``-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``
4411 Creates an anonymous memory file backend object, which allows
4412 QEMU to share the memory with an external process (e.g. when
4413 using vhost-user). The memory is allocated with memfd and
4414 optional sealing. (Linux only)
4416 The ``seal`` option creates a sealed-file, that will block
4417 further resizing the memory ('on' by default).
4419 The ``hugetlb`` option specify the file to be created resides in
4420 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
4421 with the ``hugetlb`` option, the ``hugetlbsize`` option specify
4422 the hugetlb page size on systems that support multiple hugetlb
4423 page sizes (it must be a power of 2 value supported by the
4426 In some versions of Linux, the ``hugetlb`` option is
4427 incompatible with the ``seal`` option (requires at least Linux
4430 Please refer to ``memory-backend-file`` for a description of the
4433 The ``share`` boolean option is on by default with memfd.
4435 ``-object rng-builtin,id=id``
4436 Creates a random number generator backend which obtains entropy
4437 from QEMU builtin functions. The ``id`` parameter is a unique ID
4438 that will be used to reference this entropy backend from the
4439 ``virtio-rng`` device. By default, the ``virtio-rng`` device
4440 uses this RNG backend.
4442 ``-object rng-random,id=id,filename=/dev/random``
4443 Creates a random number generator backend which obtains entropy
4444 from a device on the host. The ``id`` parameter is a unique ID
4445 that will be used to reference this entropy backend from the
4446 ``virtio-rng`` device. The ``filename`` parameter specifies
4447 which file to obtain entropy from and if omitted defaults to
4450 ``-object rng-egd,id=id,chardev=chardevid``
4451 Creates a random number generator backend which obtains entropy
4452 from an external daemon running on the host. The ``id``
4453 parameter is a unique ID that will be used to reference this
4454 entropy backend from the ``virtio-rng`` device. The ``chardev``
4455 parameter is the unique ID of a character device backend that
4456 provides the connection to the RNG daemon.
4458 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
4459 Creates a TLS anonymous credentials object, which can be used to
4460 provide TLS support on network backends. The ``id`` parameter is
4461 a unique ID which network backends will use to access the
4462 credentials. The ``endpoint`` is either ``server`` or ``client``
4463 depending on whether the QEMU network backend that uses the
4464 credentials will be acting as a client or as a server. If
4465 ``verify-peer`` is enabled (the default) then once the handshake
4466 is completed, the peer credentials will be verified, though this
4467 is a no-op for anonymous credentials.
4469 The dir parameter tells QEMU where to find the credential files.
4470 For server endpoints, this directory may contain a file
4471 dh-params.pem providing diffie-hellman parameters to use for the
4472 TLS server. If the file is missing, QEMU will generate a set of
4473 DH parameters at startup. This is a computationally expensive
4474 operation that consumes random pool entropy, so it is
4475 recommended that a persistent set of parameters be generated
4478 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
4479 Creates a TLS Pre-Shared Keys (PSK) credentials object, which
4480 can be used to provide TLS support on network backends. The
4481 ``id`` parameter is a unique ID which network backends will use
4482 to access the credentials. The ``endpoint`` is either ``server``
4483 or ``client`` depending on whether the QEMU network backend that
4484 uses the credentials will be acting as a client or as a server.
4485 For clients only, ``username`` is the username which will be
4486 sent to the server. If omitted it defaults to "qemu".
4488 The dir parameter tells QEMU where to find the keys file. It is
4489 called "dir/keys.psk" and contains "username:key" pairs. This
4490 file can most easily be created using the GnuTLS ``psktool``
4493 For server endpoints, dir may also contain a file dh-params.pem
4494 providing diffie-hellman parameters to use for the TLS server.
4495 If the file is missing, QEMU will generate a set of DH
4496 parameters at startup. This is a computationally expensive
4497 operation that consumes random pool entropy, so it is
4498 recommended that a persistent set of parameters be generated up
4501 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
4502 Creates a TLS anonymous credentials object, which can be used to
4503 provide TLS support on network backends. The ``id`` parameter is
4504 a unique ID which network backends will use to access the
4505 credentials. The ``endpoint`` is either ``server`` or ``client``
4506 depending on whether the QEMU network backend that uses the
4507 credentials will be acting as a client or as a server. If
4508 ``verify-peer`` is enabled (the default) then once the handshake
4509 is completed, the peer credentials will be verified. With x509
4510 certificates, this implies that the clients must be provided
4511 with valid client certificates too.
4513 The dir parameter tells QEMU where to find the credential files.
4514 For server endpoints, this directory may contain a file
4515 dh-params.pem providing diffie-hellman parameters to use for the
4516 TLS server. If the file is missing, QEMU will generate a set of
4517 DH parameters at startup. This is a computationally expensive
4518 operation that consumes random pool entropy, so it is
4519 recommended that a persistent set of parameters be generated
4522 For x509 certificate credentials the directory will contain
4523 further files providing the x509 certificates. The certificates
4524 must be stored in PEM format, in filenames ca-cert.pem,
4525 ca-crl.pem (optional), server-cert.pem (only servers),
4526 server-key.pem (only servers), client-cert.pem (only clients),
4527 and client-key.pem (only clients).
4529 For the server-key.pem and client-key.pem files which contain
4530 sensitive private keys, it is possible to use an encrypted
4531 version by providing the passwordid parameter. This provides the
4532 ID of a previously created ``secret`` object containing the
4533 password for decryption.
4535 The priority parameter allows to override the global default
4536 priority used by gnutls. This can be useful if the system
4537 administrator needs to use a weaker set of crypto priorities for
4538 QEMU without potentially forcing the weakness onto all
4539 applications. Or conversely if one wants wants a stronger
4540 default for QEMU than for all other applications, they can do
4541 this through this parameter. Its format is a gnutls priority
4542 string as described at
4543 https://gnutls.org/manual/html_node/Priority-Strings.html.
4545 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
4546 Interval t can't be 0, this filter batches the packet delivery:
4547 all packets arriving in a given interval on netdev netdevid are
4548 delayed until the end of the interval. Interval is in
4549 microseconds. ``status`` is optional that indicate whether the
4550 netfilter is on (enabled) or off (disabled), the default status
4551 for netfilter will be 'on'.
4553 queue all\|rx\|tx is an option that can be applied to any
4556 ``all``: the filter is attached both to the receive and the
4557 transmit queue of the netdev (default).
4559 ``rx``: the filter is attached to the receive queue of the
4560 netdev, where it will receive packets sent to the netdev.
4562 ``tx``: the filter is attached to the transmit queue of the
4563 netdev, where it will receive packets sent by the netdev.
4565 position head\|tail\|id=<id> is an option to specify where the
4566 filter should be inserted in the filter list. It can be applied
4569 ``head``: the filter is inserted at the head of the filter list,
4570 before any existing filters.
4572 ``tail``: the filter is inserted at the tail of the filter list,
4573 behind any existing filters (default).
4575 ``id=<id>``: the filter is inserted before or behind the filter
4576 specified by <id>, see the insert option below.
4578 insert behind\|before is an option to specify where to insert
4579 the new filter relative to the one specified with
4580 position=id=<id>. It can be applied to any netfilter.
4582 ``before``: insert before the specified filter.
4584 ``behind``: insert behind the specified filter (default).
4586 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4587 filter-mirror on netdev netdevid,mirror net packet to
4588 chardevchardevid, if it has the vnet\_hdr\_support flag,
4589 filter-mirror will mirror packet with vnet\_hdr\_len.
4591 ``-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]``
4592 filter-redirector on netdev netdevid,redirect filter's net
4593 packet to chardev chardevid,and redirect indev's packet to
4594 filter.if it has the vnet\_hdr\_support flag, filter-redirector
4595 will redirect packet with vnet\_hdr\_len. Create a
4596 filter-redirector we need to differ outdev id from indev id, id
4597 can not be the same. we can just use indev or outdev, but at
4598 least one of indev or outdev need to be specified.
4600 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]``
4601 Filter-rewriter is a part of COLO project.It will rewrite tcp
4602 packet to secondary from primary to keep secondary tcp
4603 connection,and rewrite tcp packet to primary from secondary make
4604 tcp packet can be handled by client.if it has the
4605 vnet\_hdr\_support flag, we can parse packet with vnet header.
4607 usage: colo secondary: -object
4608 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object
4609 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object
4610 filter-rewriter,id=rew0,netdev=hn0,queue=all
4612 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]``
4613 Dump the network traffic on netdev dev to the file specified by
4614 filename. At most len bytes (64k by default) per packet are
4615 stored. The file format is libpcap, so it can be analyzed with
4616 tools such as tcpdump or Wireshark.
4618 ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id]``
4619 Colo-compare gets packet from primary\_inchardevid and
4620 secondary\_inchardevid, than compare primary packet with
4621 secondary packet. If the packets are same, we will output
4622 primary packet to outdevchardevid, else we will notify
4623 colo-frame do checkpoint and send primary packet to
4624 outdevchardevid. In order to improve efficiency, we need to put
4625 the task of comparison in another thread. If it has the
4626 vnet\_hdr\_support flag, colo compare will send/recv packet with
4627 vnet\_hdr\_len. If you want to use Xen COLO, will need the
4628 notify\_dev to notify Xen colo-frame to do checkpoint.
4630 we must use it with the help of filter-mirror and
4638 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4639 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4640 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4641 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4642 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4643 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4644 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4645 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4646 -object iothread,id=iothread1
4647 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4648 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4649 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4650 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
4653 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4654 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4655 -chardev socket,id=red0,host=3.3.3.3,port=9003
4656 -chardev socket,id=red1,host=3.3.3.3,port=9004
4657 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4658 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4664 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4665 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4666 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4667 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4668 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4669 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4670 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4671 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4672 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait
4673 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4674 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4675 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4676 -object iothread,id=iothread1
4677 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1
4680 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4681 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4682 -chardev socket,id=red0,host=3.3.3.3,port=9003
4683 -chardev socket,id=red1,host=3.3.3.3,port=9004
4684 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4685 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4687 If you want to know the detail of above command line, you can
4688 read the colo-compare git log.
4690 ``-object cryptodev-backend-builtin,id=id[,queues=queues]``
4691 Creates a cryptodev backend which executes crypto opreation from
4692 the QEMU cipher APIS. The id parameter is a unique ID that will
4693 be used to reference this cryptodev backend from the
4694 ``virtio-crypto`` device. The queues parameter is optional,
4695 which specify the queue number of cryptodev backend, the default
4702 -object cryptodev-backend-builtin,id=cryptodev0 \
4703 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
4706 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]``
4707 Creates a vhost-user cryptodev backend, backed by a chardev
4708 chardevid. The id parameter is a unique ID that will be used to
4709 reference this cryptodev backend from the ``virtio-crypto``
4710 device. The chardev should be a unix domain socket backed one.
4711 The vhost-user uses a specifically defined protocol to pass
4712 vhost ioctl replacement messages to an application on the other
4713 end of the socket. The queues parameter is optional, which
4714 specify the queue number of cryptodev backend for multiqueue
4715 vhost-user, the default of queues is 1.
4721 -chardev socket,id=chardev0,path=/path/to/socket \
4722 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \
4723 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
4726 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]``
4728 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]``
4729 Defines a secret to store a password, encryption key, or some
4730 other sensitive data. The sensitive data can either be passed
4731 directly via the data parameter, or indirectly via the file
4732 parameter. Using the data parameter is insecure unless the
4733 sensitive data is encrypted.
4735 The sensitive data can be provided in raw format (the default),
4736 or base64. When encoded as JSON, the raw format only supports
4737 valid UTF-8 characters, so base64 is recommended for sending
4738 binary data. QEMU will convert from which ever format is
4739 provided to the format it needs internally. eg, an RBD password
4740 can be provided in raw format, even though it will be base64
4741 encoded when passed onto the RBD sever.
4743 For added protection, it is possible to encrypt the data
4744 associated with a secret using the AES-256-CBC cipher. Use of
4745 encryption is indicated by providing the keyid and iv
4746 parameters. The keyid parameter provides the ID of a previously
4747 defined secret that contains the AES-256 decryption key. This
4748 key should be 32-bytes long and be base64 encoded. The iv
4749 parameter provides the random initialization vector used for
4750 encryption of this particular secret and should be a base64
4751 encrypted string of the 16-byte IV.
4753 The simplest (insecure) usage is to provide the secret inline
4757 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw
4759 The simplest secure usage is to provide the secret via a file
4761 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object
4762 secret,id=sec0,file=mypasswd.txt,format=raw
4764 For greater security, AES-256-CBC should be used. To illustrate
4765 usage, consider the openssl command line tool which can encrypt
4766 the data. Note that when encrypting, the plaintext must be
4767 padded to the cipher block size (32 bytes) using the standard
4768 PKCS#5/6 compatible padding algorithm.
4770 First a master key needs to be created in base64 encoding:
4774 # openssl rand -base64 32 > key.b64
4775 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"')
4777 Each secret to be encrypted needs to have a random
4778 initialization vector generated. These do not need to be kept
4783 # openssl rand -base64 16 > iv.b64
4784 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"')
4786 The secret to be defined can now be encrypted, in this case
4787 we're telling openssl to base64 encode the result, but it could
4788 be left as raw bytes if desired.
4792 # SECRET=$(printf "letmein" |
4793 openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
4795 When launching QEMU, create a master secret pointing to
4796 ``key.b64`` and specify that to be used to decrypt the user
4797 password. Pass the contents of ``iv.b64`` to the second secret
4802 -object secret,id=secmaster0,format=base64,file=key.b64 \
4803 -object secret,id=sec0,keyid=secmaster0,format=base64,\
4804 data=$SECRET,iv=$(<iv.b64)
4806 ``-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]``
4807 Create a Secure Encrypted Virtualization (SEV) guest object,
4808 which can be used to provide the guest memory encryption support
4811 When memory encryption is enabled, one of the physical address
4812 bit (aka the C-bit) is utilized to mark if a memory page is
4813 protected. The ``cbitpos`` is used to provide the C-bit
4814 position. The C-bit position is Host family dependent hence user
4815 must provide this value. On EPYC, the value should be 47.
4817 When memory encryption is enabled, we loose certain bits in
4818 physical address space. The ``reduced-phys-bits`` is used to
4819 provide the number of bits we loose in physical address space.
4820 Similar to C-bit, the value is Host family dependent. On EPYC,
4821 the value should be 5.
4823 The ``sev-device`` provides the device file to use for
4824 communicating with the SEV firmware running inside AMD Secure
4825 Processor. The default device is '/dev/sev'. If hardware
4826 supports memory encryption then /dev/sev devices are created by
4829 The ``policy`` provides the guest policy to be enforced by the
4830 SEV firmware and restrict what configuration and operational
4831 commands can be performed on this guest by the hypervisor. The
4832 policy should be provided by the guest owner and is bound to the
4833 guest and cannot be changed throughout the lifetime of the
4834 guest. The default is 0.
4836 If guest ``policy`` allows sharing the key with another SEV
4837 guest then ``handle`` can be use to provide handle of the guest
4838 from which to share the key.
4840 The ``dh-cert-file`` and ``session-file`` provides the guest
4841 owner's Public Diffie-Hillman key defined in SEV spec. The PDH
4842 and session parameters are used for establishing a cryptographic
4843 session with the guest owner to negotiate keys used for
4844 attestation. The file must be encoded in base64.
4846 e.g to launch a SEV guest
4850 # |qemu_system_x86| \
4852 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \
4853 -machine ...,memory-encryption=sev0
4856 ``-object authz-simple,id=id,identity=string``
4857 Create an authorization object that will control access to
4860 The ``identity`` parameter is identifies the user and its format
4861 depends on the network service that authorization object is
4862 associated with. For authorizing based on TLS x509 certificates,
4863 the identity must be the x509 distinguished name. Note that care
4864 must be taken to escape any commas in the distinguished name.
4866 An example authorization object to validate a x509 distinguished
4867 name would look like:
4873 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \
4876 Note the use of quotes due to the x509 distinguished name
4877 containing whitespace, and escaping of ','.
4879 ``-object authz-listfile,id=id,filename=path,refresh=yes|no``
4880 Create an authorization object that will control access to
4883 The ``filename`` parameter is the fully qualified path to a file
4884 containing the access control list rules in JSON format.
4886 An example set of rules that match against SASL usernames might
4893 { "match": "fred", "policy": "allow", "format": "exact" },
4894 { "match": "bob", "policy": "allow", "format": "exact" },
4895 { "match": "danb", "policy": "deny", "format": "glob" },
4896 { "match": "dan*", "policy": "allow", "format": "exact" },
4901 When checking access the object will iterate over all the rules
4902 and the first rule to match will have its ``policy`` value
4903 returned as the result. If no rules match, then the default
4904 ``policy`` value is returned.
4906 The rules can either be an exact string match, or they can use
4907 the simple UNIX glob pattern matching to allow wildcards to be
4910 If ``refresh`` is set to true the file will be monitored and
4911 automatically reloaded whenever its content changes.
4913 As with the ``authz-simple`` object, the format of the identity
4914 strings being matched depends on the network service, but is
4915 usually a TLS x509 distinguished name, or a SASL username.
4917 An example authorization object to validate a SASL username
4924 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=yes
4927 ``-object authz-pam,id=id,service=string``
4928 Create an authorization object that will control access to
4931 The ``service`` parameter provides the name of a PAM service to
4932 use for authorization. It requires that a file
4933 ``/etc/pam.d/service`` exist to provide the configuration for
4934 the ``account`` subsystem.
4936 An example authorization object to validate a TLS x509
4937 distinguished name would look like:
4943 -object authz-pam,id=auth0,service=qemu-vnc
4946 There would then be a corresponding config file for PAM at
4947 ``/etc/pam.d/qemu-vnc`` that contains:
4951 account requisite pam_listfile.so item=user sense=allow \
4952 file=/etc/qemu/vnc.allow
4954 Finally the ``/etc/qemu/vnc.allow`` file would contain the list
4955 of x509 distingished names that are permitted access
4959 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
4961 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink``
4962 Creates a dedicated event loop thread that devices can be
4963 assigned to. This is known as an IOThread. By default device
4964 emulation happens in vCPU threads or the main event loop thread.
4965 This can become a scalability bottleneck. IOThreads allow device
4966 emulation and I/O to run on other host CPUs.
4968 The ``id`` parameter is a unique ID that will be used to
4969 reference this IOThread from ``-device ...,iothread=id``.
4970 Multiple devices can be assigned to an IOThread. Note that not
4971 all devices support an ``iothread`` parameter.
4973 The ``query-iothreads`` QMP command lists IOThreads and reports
4974 their thread IDs so that the user can configure host CPU
4977 IOThreads use an adaptive polling algorithm to reduce event loop
4978 latency. Instead of entering a blocking system call to monitor
4979 file descriptors and then pay the cost of being woken up when an
4980 event occurs, the polling algorithm spins waiting for events for
4981 a short time. The algorithm's default parameters are suitable
4982 for many cases but can be adjusted based on knowledge of the
4983 workload and/or host device latency.
4985 The ``poll-max-ns`` parameter is the maximum number of
4986 nanoseconds to busy wait for events. Polling can be disabled by
4987 setting this value to 0.
4989 The ``poll-grow`` parameter is the multiplier used to increase
4990 the polling time when the algorithm detects it is missing events
4991 due to not polling long enough.
4993 The ``poll-shrink`` parameter is the divisor used to decrease
4994 the polling time when the algorithm detects it is spending too
4995 long polling without encountering events.
4997 The polling parameters can be modified at run-time using the
4998 ``qom-set`` command (where ``iothread1`` is the IOThread's
5003 (qemu) qom-set /objects/iothread1 poll-max-ns 100000
5007 HXCOMM This is the last statement. Insert new options before this line!