1 HXCOMM Use DEFHEADING() to define headings in both help text and texi
2 HXCOMM Text between STEXI and ETEXI are copied to texi 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 texi and C
9 DEFHEADING(Standard options:)
14 DEF("help", 0, QEMU_OPTION_h,
15 "-h or -help display this help and exit\n", QEMU_ARCH_ALL)
22 DEF("version", 0, QEMU_OPTION_version,
23 "-version display version information and exit\n", QEMU_ARCH_ALL)
27 Display version information and exit
30 DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
31 "-machine [type=]name[,prop[=value][,...]]\n"
32 " selects emulated machine ('-machine help' for list)\n"
33 " property accel=accel1[:accel2[:...]] selects accelerator\n"
34 " supported accelerators are kvm, xen, hax, hvf, whpx or tcg (default: tcg)\n"
35 " kernel_irqchip=on|off|split controls accelerated irqchip support (default=off)\n"
36 " vmport=on|off|auto controls emulation of vmport (default: auto)\n"
37 " kvm_shadow_mem=size of KVM shadow MMU in bytes\n"
38 " dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
39 " mem-merge=on|off controls memory merge support (default: on)\n"
40 " igd-passthru=on|off controls IGD GFX passthrough support (default=off)\n"
41 " aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
42 " dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
43 " suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
44 " nvdimm=on|off controls NVDIMM support (default=off)\n"
45 " enforce-config-section=on|off enforce configuration section migration (default=off)\n"
46 " memory-encryption=@var{} memory encryption object to use (default=none)\n",
49 @item -machine [type=]@var{name}[,prop=@var{value}[,...]]
51 Select the emulated machine by @var{name}. Use @code{-machine help} to list
54 For architectures which aim to support live migration compatibility
55 across releases, each release will introduce a new versioned machine
56 type. For example, the 2.8.0 release introduced machine types
57 ``pc-i440fx-2.8'' and ``pc-q35-2.8'' for the x86_64/i686 architectures.
59 To allow live migration of guests from QEMU version 2.8.0, to QEMU
60 version 2.9.0, the 2.9.0 version must support the ``pc-i440fx-2.8''
61 and ``pc-q35-2.8'' machines too. To allow users live migrating VMs
62 to skip multiple intermediate releases when upgrading, new releases
63 of QEMU will support machine types from many previous versions.
65 Supported machine properties are:
67 @item accel=@var{accels1}[:@var{accels2}[:...]]
68 This is used to enable an accelerator. Depending on the target architecture,
69 kvm, xen, hax, hvf, whpx or tcg can be available. By default, tcg is used. If there is
70 more than one accelerator specified, the next one is used if the previous one
72 @item kernel_irqchip=on|off
73 Controls in-kernel irqchip support for the chosen accelerator when available.
74 @item gfx_passthru=on|off
75 Enables IGD GFX passthrough support for the chosen machine when available.
76 @item vmport=on|off|auto
77 Enables emulation of VMWare IO port, for vmmouse etc. auto says to select the
78 value based on accel. For accel=xen the default is off otherwise the default
80 @item kvm_shadow_mem=size
81 Defines the size of the KVM shadow MMU.
82 @item dump-guest-core=on|off
83 Include guest memory in a core dump. The default is on.
84 @item mem-merge=on|off
85 Enables or disables memory merge support. This feature, when supported by
86 the host, de-duplicates identical memory pages among VMs instances
88 @item aes-key-wrap=on|off
89 Enables or disables AES key wrapping support on s390-ccw hosts. This feature
90 controls whether AES wrapping keys will be created to allow
91 execution of AES cryptographic functions. The default is on.
92 @item dea-key-wrap=on|off
93 Enables or disables DEA key wrapping support on s390-ccw hosts. This feature
94 controls whether DEA wrapping keys will be created to allow
95 execution of DEA cryptographic functions. The default is on.
97 Enables or disables NVDIMM support. The default is off.
98 @item enforce-config-section=on|off
99 If @option{enforce-config-section} is set to @var{on}, force migration
100 code to send configuration section even if the machine-type sets the
101 @option{migration.send-configuration} property to @var{off}.
102 NOTE: this parameter is deprecated. Please use @option{-global}
103 @option{migration.send-configuration}=@var{on|off} instead.
104 @item memory-encryption=@var{}
105 Memory encryption object to use. The default is none.
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)
115 @item -cpu @var{model}
117 Select CPU model (@code{-cpu help} for list and additional feature selection)
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 " tb-size=n (TCG translation block cache size)\n"
124 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
126 @item -accel @var{name}[,prop=@var{value}[,...]]
128 This is used to enable an accelerator. Depending on the target architecture,
129 kvm, xen, hax, hvf, whpx or tcg can be available. By default, tcg is used. If there is
130 more than one accelerator specified, the next one is used if the previous one
133 @item tb-size=@var{n}
134 Controls the size (in MiB) of the TCG translation block cache.
135 @item thread=single|multi
136 Controls number of TCG threads. When the TCG is multi-threaded there will be one
137 thread per vCPU therefor taking advantage of additional host cores. The default
138 is to enable multi-threading where both the back-end and front-ends support it and
139 no incompatible TCG features have been enabled (e.g. icount/replay).
143 DEF("smp", HAS_ARG, QEMU_OPTION_smp,
144 "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n"
145 " set the number of CPUs to 'n' [default=1]\n"
146 " maxcpus= maximum number of total cpus, including\n"
147 " offline CPUs for hotplug, etc\n"
148 " cores= number of CPU cores on one socket (for PC, it's on one die)\n"
149 " threads= number of threads on one CPU core\n"
150 " dies= number of CPU dies on one socket (for PC only)\n"
151 " sockets= number of discrete sockets in the system\n",
154 @item -smp [cpus=]@var{n}[,cores=@var{cores}][,threads=@var{threads}][,dies=dies][,sockets=@var{sockets}][,maxcpus=@var{maxcpus}]
156 Simulate an SMP system with @var{n} CPUs. On the PC target, up to 255
157 CPUs are supported. On Sparc32 target, Linux limits the number of usable CPUs
159 For the PC target, the number of @var{cores} per die, the number of @var{threads}
160 per cores, the number of @var{dies} per packages and the total number of
161 @var{sockets} can be specified. Missing values will be computed.
162 If any on the three values is given, the total number of CPUs @var{n} can be omitted.
163 @var{maxcpus} specifies the maximum number of hotpluggable CPUs.
166 DEF("numa", HAS_ARG, QEMU_OPTION_numa,
167 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node]\n"
168 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node]\n"
169 "-numa dist,src=source,dst=destination,val=distance\n"
170 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n",
173 @item -numa node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
174 @itemx -numa node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}]
175 @itemx -numa dist,src=@var{source},dst=@var{destination},val=@var{distance}
176 @itemx -numa cpu,node-id=@var{node}[,socket-id=@var{x}][,core-id=@var{y}][,thread-id=@var{z}]
178 Define a NUMA node and assign RAM and VCPUs to it.
179 Set the NUMA distance from a source node to a destination node.
181 Legacy VCPU assignment uses @samp{cpus} option where
182 @var{firstcpu} and @var{lastcpu} are CPU indexes. Each
183 @samp{cpus} option represent a contiguous range of CPU indexes
184 (or a single VCPU if @var{lastcpu} is omitted). A non-contiguous
185 set of VCPUs can be represented by providing multiple @samp{cpus}
186 options. If @samp{cpus} is omitted on all nodes, VCPUs are automatically
189 For example, the following option assigns VCPUs 0, 1, 2 and 5 to
192 -numa node,cpus=0-2,cpus=5
195 @samp{cpu} option is a new alternative to @samp{cpus} option
196 which uses @samp{socket-id|core-id|thread-id} properties to assign
197 CPU objects to a @var{node} using topology layout properties of CPU.
198 The set of properties is machine specific, and depends on used
199 machine type/@samp{smp} options. It could be queried with
200 @samp{hotpluggable-cpus} monitor command.
201 @samp{node-id} property specifies @var{node} to which CPU object
202 will be assigned, it's required for @var{node} to be declared
203 with @samp{node} option before it's used with @samp{cpu} option.
208 -smp 1,sockets=2,maxcpus=2 \
209 -numa node,nodeid=0 -numa node,nodeid=1 \
210 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
213 @samp{mem} assigns a given RAM amount to a node. @samp{memdev}
214 assigns RAM from a given memory backend device to a node. If
215 @samp{mem} and @samp{memdev} are omitted in all nodes, RAM is
216 split equally between them.
218 @samp{mem} and @samp{memdev} are mutually exclusive. Furthermore,
219 if one node uses @samp{memdev}, all of them have to use it.
221 @var{source} and @var{destination} are NUMA node IDs.
222 @var{distance} is the NUMA distance from @var{source} to @var{destination}.
223 The distance from a node to itself is always 10. If any pair of nodes is
224 given a distance, then all pairs must be given distances. Although, when
225 distances are only given in one direction for each pair of nodes, then
226 the distances in the opposite directions are assumed to be the same. If,
227 however, an asymmetrical pair of distances is given for even one node
228 pair, then all node pairs must be provided distance values for both
229 directions, even when they are symmetrical. When a node is unreachable
230 from another node, set the pair's distance to 255.
232 Note that the -@option{numa} option doesn't allocate any of the
233 specified resources, it just assigns existing resources to NUMA
234 nodes. This means that one still has to use the @option{-m},
235 @option{-smp} options to allocate RAM and VCPUs respectively.
239 DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
240 "-add-fd fd=fd,set=set[,opaque=opaque]\n"
241 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
243 @item -add-fd fd=@var{fd},set=@var{set}[,opaque=@var{opaque}]
246 Add a file descriptor to an fd set. Valid options are:
250 This option defines the file descriptor of which a duplicate is added to fd set.
251 The file descriptor cannot be stdin, stdout, or stderr.
253 This option defines the ID of the fd set to add the file descriptor to.
254 @item opaque=@var{opaque}
255 This option defines a free-form string that can be used to describe @var{fd}.
258 You can open an image using pre-opened file descriptors from an fd set:
260 @value{qemu_system} \
261 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
262 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
263 -drive file=/dev/fdset/2,index=0,media=disk
267 DEF("set", HAS_ARG, QEMU_OPTION_set,
268 "-set group.id.arg=value\n"
269 " set <arg> parameter for item <id> of type <group>\n"
270 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
272 @item -set @var{group}.@var{id}.@var{arg}=@var{value}
274 Set parameter @var{arg} for item @var{id} of type @var{group}
277 DEF("global", HAS_ARG, QEMU_OPTION_global,
278 "-global driver.property=value\n"
279 "-global driver=driver,property=property,value=value\n"
280 " set a global default for a driver property\n",
283 @item -global @var{driver}.@var{prop}=@var{value}
284 @itemx -global driver=@var{driver},property=@var{property},value=@var{value}
286 Set default value of @var{driver}'s property @var{prop} to @var{value}, e.g.:
289 @value{qemu_system_x86} -global ide-hd.physical_block_size=4096 disk-image.img
292 In particular, you can use this to set driver properties for devices which are
293 created automatically by the machine model. To create a device which is not
294 created automatically and set properties on it, use -@option{device}.
296 -global @var{driver}.@var{prop}=@var{value} is shorthand for -global
297 driver=@var{driver},property=@var{prop},value=@var{value}. The
298 longhand syntax works even when @var{driver} contains a dot.
301 DEF("boot", HAS_ARG, QEMU_OPTION_boot,
302 "-boot [order=drives][,once=drives][,menu=on|off]\n"
303 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
304 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
305 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
306 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n"
307 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
310 @item -boot [order=@var{drives}][,once=@var{drives}][,menu=on|off][,splash=@var{sp_name}][,splash-time=@var{sp_time}][,reboot-timeout=@var{rb_timeout}][,strict=on|off]
312 Specify boot order @var{drives} as a string of drive letters. Valid
313 drive letters depend on the target architecture. The x86 PC uses: a, b
314 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p (Etherboot
315 from network adapter 1-4), hard disk boot is the default. To apply a
316 particular boot order only on the first startup, specify it via
317 @option{once}. Note that the @option{order} or @option{once} parameter
318 should not be used together with the @option{bootindex} property of
319 devices, since the firmware implementations normally do not support both
322 Interactive boot menus/prompts can be enabled via @option{menu=on} as far
323 as firmware/BIOS supports them. The default is non-interactive boot.
325 A splash picture could be passed to bios, enabling user to show it as logo,
326 when option splash=@var{sp_name} is given and menu=on, If firmware/BIOS
327 supports them. Currently Seabios for X86 system support it.
328 limitation: The splash file could be a jpeg file or a BMP file in 24 BPP
329 format(true color). The resolution should be supported by the SVGA mode, so
330 the recommended is 320x240, 640x480, 800x640.
332 A timeout could be passed to bios, guest will pause for @var{rb_timeout} ms
333 when boot failed, then reboot. If @option{reboot-timeout} is not set,
334 guest will not reboot by default. Currently Seabios for X86
337 Do strict boot via @option{strict=on} as far as firmware/BIOS
338 supports it. This only effects when boot priority is changed by
339 bootindex options. The default is non-strict boot.
342 # try to boot from network first, then from hard disk
343 @value{qemu_system_x86} -boot order=nc
344 # boot from CD-ROM first, switch back to default order after reboot
345 @value{qemu_system_x86} -boot once=d
346 # boot with a splash picture for 5 seconds.
347 @value{qemu_system_x86} -boot menu=on,splash=/root/boot.bmp,splash-time=5000
350 Note: The legacy format '-boot @var{drives}' is still supported but its
351 use is discouraged as it may be removed from future versions.
354 DEF("m", HAS_ARG, QEMU_OPTION_m,
355 "-m [size=]megs[,slots=n,maxmem=size]\n"
356 " configure guest RAM\n"
357 " size: initial amount of guest memory\n"
358 " slots: number of hotplug slots (default: none)\n"
359 " maxmem: maximum amount of guest memory (default: none)\n"
360 "NOTE: Some architectures might enforce a specific granularity\n",
363 @item -m [size=]@var{megs}[,slots=n,maxmem=size]
365 Sets guest startup RAM size to @var{megs} megabytes. Default is 128 MiB.
366 Optionally, a suffix of ``M'' or ``G'' can be used to signify a value in
367 megabytes or gigabytes respectively. Optional pair @var{slots}, @var{maxmem}
368 could be used to set amount of hotpluggable memory slots and maximum amount of
369 memory. Note that @var{maxmem} must be aligned to the page size.
371 For example, the following command-line sets the guest startup RAM size to
372 1GB, creates 3 slots to hotplug additional memory and sets the maximum
373 memory the guest can reach to 4GB:
376 @value{qemu_system} -m 1G,slots=3,maxmem=4G
379 If @var{slots} and @var{maxmem} are not specified, memory hotplug won't
380 be enabled and the guest startup RAM will never increase.
383 DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
384 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
386 @item -mem-path @var{path}
388 Allocate guest RAM from a temporarily created file in @var{path}.
391 DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
392 "-mem-prealloc preallocate guest memory (use with -mem-path)\n",
396 @findex -mem-prealloc
397 Preallocate memory when using -mem-path.
400 DEF("k", HAS_ARG, QEMU_OPTION_k,
401 "-k language use keyboard layout (for example 'fr' for French)\n",
404 @item -k @var{language}
406 Use keyboard layout @var{language} (for example @code{fr} for
407 French). This option is only needed where it is not easy to get raw PC
408 keycodes (e.g. on Macs, with some X11 servers or with a VNC or curses
409 display). You don't normally need to use it on PC/Linux or PC/Windows
412 The available layouts are:
414 ar de-ch es fo fr-ca hu ja mk no pt-br sv
415 da en-gb et fr fr-ch is lt nl pl ru th
416 de en-us fi fr-be hr it lv nl-be pt sl tr
419 The default is @code{en-us}.
423 HXCOMM Deprecated by -audiodev
424 DEF("audio-help", 0, QEMU_OPTION_audio_help,
425 "-audio-help show -audiodev equivalent of the currently specified audio settings\n",
430 Will show the -audiodev equivalent of the currently specified
431 (deprecated) environment variables.
434 DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
435 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
436 " specifies the audio backend to use\n"
437 " id= identifier of the backend\n"
438 " timer-period= timer period in microseconds\n"
439 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
440 " in|out.fixed-settings= use fixed settings for host audio\n"
441 " in|out.frequency= frequency to use with fixed settings\n"
442 " in|out.channels= number of channels to use with fixed settings\n"
443 " in|out.format= sample format to use with fixed settings\n"
444 " valid values: s8, s16, s32, u8, u16, u32\n"
445 " in|out.voices= number of voices to use\n"
446 " in|out.buffer-length= length of buffer in microseconds\n"
447 "-audiodev none,id=id,[,prop[=value][,...]]\n"
448 " dummy driver that discards all output\n"
449 #ifdef CONFIG_AUDIO_ALSA
450 "-audiodev alsa,id=id[,prop[=value][,...]]\n"
451 " in|out.dev= name of the audio device to use\n"
452 " in|out.period-length= length of period in microseconds\n"
453 " in|out.try-poll= attempt to use poll mode\n"
454 " threshold= threshold (in microseconds) when playback starts\n"
456 #ifdef CONFIG_AUDIO_COREAUDIO
457 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
458 " in|out.buffer-count= number of buffers\n"
460 #ifdef CONFIG_AUDIO_DSOUND
461 "-audiodev dsound,id=id[,prop[=value][,...]]\n"
462 " latency= add extra latency to playback in microseconds\n"
464 #ifdef CONFIG_AUDIO_OSS
465 "-audiodev oss,id=id[,prop[=value][,...]]\n"
466 " in|out.dev= path of the audio device to use\n"
467 " in|out.buffer-count= number of buffers\n"
468 " in|out.try-poll= attempt to use poll mode\n"
469 " try-mmap= try using memory mapped access\n"
470 " exclusive= open device in exclusive mode\n"
471 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
473 #ifdef CONFIG_AUDIO_PA
474 "-audiodev pa,id=id[,prop[=value][,...]]\n"
475 " server= PulseAudio server address\n"
476 " in|out.name= source/sink device name\n"
477 " in|out.latency= desired latency in microseconds\n"
479 #ifdef CONFIG_AUDIO_SDL
480 "-audiodev sdl,id=id[,prop[=value][,...]]\n"
483 "-audiodev spice,id=id[,prop[=value][,...]]\n"
485 "-audiodev wav,id=id[,prop[=value][,...]]\n"
486 " path= path of wav file to record\n",
489 @item -audiodev [driver=]@var{driver},id=@var{id}[,@var{prop}[=@var{value}][,...]]
491 Adds a new audio backend @var{driver} identified by @var{id}. There are
492 global and driver specific properties. Some values can be set
493 differently for input and output, they're marked with @code{in|out.}.
494 You can set the input's property with @code{in.@var{prop}} and the
495 output's property with @code{out.@var{prop}}. For example:
497 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
498 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
501 NOTE: parameter validation is known to be incomplete, in many cases
502 specifying an invalid option causes QEMU to print an error message and
503 continue emulation without sound.
505 Valid global options are:
508 @item id=@var{identifier}
509 Identifies the audio backend.
511 @item timer-period=@var{period}
512 Sets the timer @var{period} used by the audio subsystem in microseconds.
513 Default is 10000 (10 ms).
515 @item in|out.mixing-engine=on|off
516 Use QEMU's mixing engine to mix all streams inside QEMU and convert
517 audio formats when not supported by the backend. When off,
518 @var{fixed-settings} must be off too. Note that disabling this option
519 means that the selected backend must support multiple streams and the
520 audio formats used by the virtual cards, otherwise you'll get no sound.
521 It's not recommended to disable this option unless you want to use 5.1
522 or 7.1 audio, as mixing engine only supports mono and stereo audio.
525 @item in|out.fixed-settings=on|off
526 Use fixed settings for host audio. When off, it will change based on
527 how the guest opens the sound card. In this case you must not specify
528 @var{frequency}, @var{channels} or @var{format}. Default is on.
530 @item in|out.frequency=@var{frequency}
531 Specify the @var{frequency} to use when using @var{fixed-settings}.
534 @item in|out.channels=@var{channels}
535 Specify the number of @var{channels} to use when using
536 @var{fixed-settings}. Default is 2 (stereo).
538 @item in|out.format=@var{format}
539 Specify the sample @var{format} to use when using @var{fixed-settings}.
540 Valid values are: @code{s8}, @code{s16}, @code{s32}, @code{u8},
541 @code{u16}, @code{u32}. Default is @code{s16}.
543 @item in|out.voices=@var{voices}
544 Specify the number of @var{voices} to use. Default is 1.
546 @item in|out.buffer-length=@var{usecs}
547 Sets the size of the buffer in microseconds.
551 @item -audiodev none,id=@var{id}[,@var{prop}[=@var{value}][,...]]
552 Creates a dummy backend that discards all outputs. This backend has no
553 backend specific properties.
555 @item -audiodev alsa,id=@var{id}[,@var{prop}[=@var{value}][,...]]
556 Creates backend using the ALSA. This backend is only available on
559 ALSA specific options are:
563 @item in|out.dev=@var{device}
564 Specify the ALSA @var{device} to use for input and/or output. Default
567 @item in|out.period-length=@var{usecs}
568 Sets the period length in microseconds.
570 @item in|out.try-poll=on|off
571 Attempt to use poll mode with the device. Default is on.
573 @item threshold=@var{threshold}
574 Threshold (in microseconds) when playback starts. Default is 0.
578 @item -audiodev coreaudio,id=@var{id}[,@var{prop}[=@var{value}][,...]]
579 Creates a backend using Apple's Core Audio. This backend is only
580 available on Mac OS and only supports playback.
582 Core Audio specific options are:
586 @item in|out.buffer-count=@var{count}
587 Sets the @var{count} of the buffers.
591 @item -audiodev dsound,id=@var{id}[,@var{prop}[=@var{value}][,...]]
592 Creates a backend using Microsoft's DirectSound. This backend is only
593 available on Windows and only supports playback.
595 DirectSound specific options are:
599 @item latency=@var{usecs}
600 Add extra @var{usecs} microseconds latency to playback. Default is
605 @item -audiodev oss,id=@var{id}[,@var{prop}[=@var{value}][,...]]
606 Creates a backend using OSS. This backend is available on most
609 OSS specific options are:
613 @item in|out.dev=@var{device}
614 Specify the file name of the OSS @var{device} to use. Default is
617 @item in|out.buffer-count=@var{count}
618 Sets the @var{count} of the buffers.
620 @item in|out.try-poll=on|of
621 Attempt to use poll mode with the device. Default is on.
623 @item try-mmap=on|off
624 Try using memory mapped device access. Default is off.
626 @item exclusive=on|off
627 Open the device in exclusive mode (vmix won't work in this case).
630 @item dsp-policy=@var{policy}
631 Sets the timing policy (between 0 and 10, where smaller number means
632 smaller latency but higher CPU usage). Use -1 to use buffer sizes
633 specified by @code{buffer} and @code{buffer-count}. This option is
634 ignored if you do not have OSS 4. Default is 5.
638 @item -audiodev pa,id=@var{id}[,@var{prop}[=@var{value}][,...]]
639 Creates a backend using PulseAudio. This backend is available on most
642 PulseAudio specific options are:
646 @item server=@var{server}
647 Sets the PulseAudio @var{server} to connect to.
649 @item in|out.name=@var{sink}
650 Use the specified source/sink for recording/playback.
652 @item in|out.latency=@var{usecs}
653 Desired latency in microseconds. The PulseAudio server will try to honor this
654 value but actual latencies may be lower or higher.
658 @item -audiodev sdl,id=@var{id}[,@var{prop}[=@var{value}][,...]]
659 Creates a backend using SDL. This backend is available on most systems,
660 but you should use your platform's native backend if possible. This
661 backend has no backend specific properties.
663 @item -audiodev spice,id=@var{id}[,@var{prop}[=@var{value}][,...]]
664 Creates a backend that sends audio through SPICE. This backend requires
665 @code{-spice} and automatically selected in that case, so usually you
666 can ignore this option. This backend has no backend specific
669 @item -audiodev wav,id=@var{id}[,@var{prop}[=@var{value}][,...]]
670 Creates a backend that writes audio to a WAV file.
672 Backend specific options are:
676 @item path=@var{path}
677 Write recorded audio into the specified file. Default is
683 DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
684 "-soundhw c1,... enable audio support\n"
685 " and only specified sound cards (comma separated list)\n"
686 " use '-soundhw help' to get the list of supported cards\n"
687 " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
689 @item -soundhw @var{card1}[,@var{card2},...] or -soundhw all
691 Enable audio and selected sound hardware. Use 'help' to print all
692 available sound hardware. For example:
695 @value{qemu_system_x86} -soundhw sb16,adlib disk.img
696 @value{qemu_system_x86} -soundhw es1370 disk.img
697 @value{qemu_system_x86} -soundhw ac97 disk.img
698 @value{qemu_system_x86} -soundhw hda disk.img
699 @value{qemu_system_x86} -soundhw all disk.img
700 @value{qemu_system_x86} -soundhw help
703 Note that Linux's i810_audio OSS kernel (for AC97) module might
704 require manually specifying clocking.
707 modprobe i810_audio clocking=48000
711 DEF("device", HAS_ARG, QEMU_OPTION_device,
712 "-device driver[,prop[=value][,...]]\n"
713 " add device (based on driver)\n"
714 " prop=value,... sets driver properties\n"
715 " use '-device help' to print all possible drivers\n"
716 " use '-device driver,help' to print all possible properties\n",
719 @item -device @var{driver}[,@var{prop}[=@var{value}][,...]]
721 Add device @var{driver}. @var{prop}=@var{value} sets driver
722 properties. Valid properties depend on the driver. To get help on
723 possible drivers and properties, use @code{-device help} and
724 @code{-device @var{driver},help}.
727 @item -device ipmi-bmc-sim,id=@var{id}[,slave_addr=@var{val}][,sdrfile=@var{file}][,furareasize=@var{val}][,furdatafile=@var{file}][,guid=@var{uuid}]
729 Add an IPMI BMC. This is a simulation of a hardware management
730 interface processor that normally sits on a system. It provides
731 a watchdog and the ability to reset and power control the system.
732 You need to connect this to an IPMI interface to make it useful
734 The IPMI slave address to use for the BMC. The default is 0x20.
735 This address is the BMC's address on the I2C network of management
736 controllers. If you don't know what this means, it is safe to ignore
741 The BMC id for interfaces to use this device.
742 @item slave_addr=@var{val}
743 Define slave address to use for the BMC. The default is 0x20.
744 @item sdrfile=@var{file}
745 file containing raw Sensor Data Records (SDR) data. The default is none.
746 @item fruareasize=@var{val}
747 size of a Field Replaceable Unit (FRU) area. The default is 1024.
748 @item frudatafile=@var{file}
749 file containing raw Field Replaceable Unit (FRU) inventory data. The default is none.
750 @item guid=@var{uuid}
751 value for the GUID for the BMC, in standard UUID format. If this is set,
752 get "Get GUID" command to the BMC will return it. Otherwise "Get GUID"
753 will return an error.
756 @item -device ipmi-bmc-extern,id=@var{id},chardev=@var{id}[,slave_addr=@var{val}]
758 Add a connection to an external IPMI BMC simulator. Instead of
759 locally emulating the BMC like the above item, instead connect
760 to an external entity that provides the IPMI services.
762 A connection is made to an external BMC simulator. If you do this, it
763 is strongly recommended that you use the "reconnect=" chardev option
764 to reconnect to the simulator if the connection is lost. Note that if
765 this is not used carefully, it can be a security issue, as the
766 interface has the ability to send resets, NMIs, and power off the VM.
767 It's best if QEMU makes a connection to an external simulator running
768 on a secure port on localhost, so neither the simulator nor QEMU is
769 exposed to any outside network.
771 See the "lanserv/README.vm" file in the OpenIPMI library for more
772 details on the external interface.
774 @item -device isa-ipmi-kcs,bmc=@var{id}[,ioport=@var{val}][,irq=@var{val}]
776 Add a KCS IPMI interafce on the ISA bus. This also adds a
777 corresponding ACPI and SMBIOS entries, if appropriate.
781 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
782 @item ioport=@var{val}
783 Define the I/O address of the interface. The default is 0xca0 for KCS.
785 Define the interrupt to use. The default is 5. To disable interrupts,
789 @item -device isa-ipmi-bt,bmc=@var{id}[,ioport=@var{val}][,irq=@var{val}]
791 Like the KCS interface, but defines a BT interface. The default port is
792 0xe4 and the default interrupt is 5.
796 DEF("name", HAS_ARG, QEMU_OPTION_name,
797 "-name string1[,process=string2][,debug-threads=on|off]\n"
798 " set the name of the guest\n"
799 " string1 sets the window title and string2 the process name\n"
800 " When debug-threads is enabled, individual threads are given a separate name\n"
801 " NOTE: The thread names are for debugging and not a stable API.\n",
804 @item -name @var{name}
806 Sets the @var{name} of the guest.
807 This name will be displayed in the SDL window caption.
808 The @var{name} will also be used for the VNC server.
809 Also optionally set the top visible process name in Linux.
810 Naming of individual threads can also be enabled on Linux to aid debugging.
813 DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
814 "-uuid %08x-%04x-%04x-%04x-%012x\n"
815 " specify machine UUID\n", QEMU_ARCH_ALL)
817 @item -uuid @var{uuid}
827 DEFHEADING(Block device options:)
832 DEF("fda", HAS_ARG, QEMU_OPTION_fda,
833 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
834 DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
836 @item -fda @var{file}
837 @itemx -fdb @var{file}
840 Use @var{file} as floppy disk 0/1 image (@pxref{disk_images}).
843 DEF("hda", HAS_ARG, QEMU_OPTION_hda,
844 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL)
845 DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
846 DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
847 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL)
848 DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
850 @item -hda @var{file}
851 @itemx -hdb @var{file}
852 @itemx -hdc @var{file}
853 @itemx -hdd @var{file}
858 Use @var{file} as hard disk 0, 1, 2 or 3 image (@pxref{disk_images}).
861 DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
862 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n",
865 @item -cdrom @var{file}
867 Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
868 @option{-cdrom} at the same time). You can use the host CD-ROM by
869 using @file{/dev/cdrom} as filename (@pxref{host_drives}).
872 DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
873 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
874 " [,cache.direct=on|off][,cache.no-flush=on|off]\n"
875 " [,read-only=on|off][,auto-read-only=on|off]\n"
876 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
877 " [,driver specific parameters...]\n"
878 " configure a block backend\n", QEMU_ARCH_ALL)
880 @item -blockdev @var{option}[,@var{option}[,@var{option}[,...]]]
883 Define a new block driver node. Some of the options apply to all block drivers,
884 other options are only accepted for a specific block driver. See below for a
885 list of generic options and options for the most common block drivers.
887 Options that expect a reference to another node (e.g. @code{file}) can be
888 given in two ways. Either you specify the node name of an already existing node
889 (file=@var{node-name}), or you define a new node inline, adding options
890 for the referenced node after a dot (file.filename=@var{path},file.aio=native).
892 A block driver node created with @option{-blockdev} can be used for a guest
893 device by specifying its node name for the @code{drive} property in a
894 @option{-device} argument that defines a block device.
897 @item Valid options for any block driver node:
901 Specifies the block driver to use for the given node.
903 This defines the name of the block driver node by which it will be referenced
904 later. The name must be unique, i.e. it must not match the name of a different
905 block driver node, or (if you use @option{-drive} as well) the ID of a drive.
907 If no node name is specified, it is automatically generated. The generated node
908 name is not intended to be predictable and changes between QEMU invocations.
909 For the top level, an explicit node name must be specified.
911 Open the node read-only. Guest write attempts will fail.
913 Note that some block drivers support only read-only access, either generally or
914 in certain configurations. In this case, the default value
915 @option{read-only=off} does not work and the option must be specified
918 If @option{auto-read-only=on} is set, QEMU may fall back to read-only usage
919 even when @option{read-only=off} is requested, or even switch between modes as
920 needed, e.g. depending on whether the image file is writable or whether a
921 writing user is attached to the node.
923 Override the image locking system of QEMU by forcing the node to utilize
924 weaker shared access for permissions where it would normally request exclusive
925 access. When there is the potential for multiple instances to have the same
926 file open (whether this invocation of QEMU is the first or the second
927 instance), both instances must permit shared access for the second instance to
928 succeed at opening the file.
930 Enabling @option{force-share=on} requires @option{read-only=on}.
932 The host page cache can be avoided with @option{cache.direct=on}. This will
933 attempt to do disk IO directly to the guest's memory. QEMU may still perform an
934 internal copy of the data.
936 In case you don't care about data integrity over host failures, you can use
937 @option{cache.no-flush=on}. This option tells QEMU that it never needs to write
938 any data to the disk but can instead keep things in cache. If anything goes
939 wrong, like your host losing power, the disk storage getting disconnected
940 accidentally, etc. your image will most probably be rendered unusable.
941 @item discard=@var{discard}
942 @var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and controls
943 whether @code{discard} (also known as @code{trim} or @code{unmap}) requests are
944 ignored or passed to the filesystem. Some machine types may not support
946 @item detect-zeroes=@var{detect-zeroes}
947 @var{detect-zeroes} is "off", "on" or "unmap" and enables the automatic
948 conversion of plain zero writes by the OS to driver specific optimized
949 zero write commands. You may even choose "unmap" if @var{discard} is set
950 to "unmap" to allow a zero write to be converted to an @code{unmap} operation.
953 @item Driver-specific options for @code{file}
955 This is the protocol-level block driver for accessing regular files.
959 The path to the image file in the local filesystem
961 Specifies the AIO backend (threads/native, default: threads)
963 Specifies whether the image file is protected with Linux OFD / POSIX locks. The
964 default is to use the Linux Open File Descriptor API if available, otherwise no
965 lock is applied. (auto/on/off, default: auto)
969 -blockdev driver=file,node-name=disk,filename=disk.img
972 @item Driver-specific options for @code{raw}
974 This is the image format block driver for raw images. It is usually
975 stacked on top of a protocol level block driver such as @code{file}.
979 Reference to or definition of the data source block driver node
980 (e.g. a @code{file} driver node)
984 -blockdev driver=file,node-name=disk_file,filename=disk.img
985 -blockdev driver=raw,node-name=disk,file=disk_file
989 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
992 @item Driver-specific options for @code{qcow2}
994 This is the image format block driver for qcow2 images. It is usually
995 stacked on top of a protocol level block driver such as @code{file}.
999 Reference to or definition of the data source block driver node
1000 (e.g. a @code{file} driver node)
1003 Reference to or definition of the backing file block device (default is taken
1004 from the image file). It is allowed to pass @code{null} here in order to disable
1005 the default backing file.
1007 @item lazy-refcounts
1008 Whether to enable the lazy refcounts feature (on/off; default is taken from the
1012 The maximum total size of the L2 table and refcount block caches in bytes
1013 (default: the sum of l2-cache-size and refcount-cache-size)
1016 The maximum size of the L2 table cache in bytes
1017 (default: if cache-size is not specified - 32M on Linux platforms, and 8M on
1018 non-Linux platforms; otherwise, as large as possible within the cache-size,
1019 while permitting the requested or the minimal refcount cache size)
1021 @item refcount-cache-size
1022 The maximum size of the refcount block cache in bytes
1023 (default: 4 times the cluster size; or if cache-size is specified, the part of
1024 it which is not used for the L2 cache)
1026 @item cache-clean-interval
1027 Clean unused entries in the L2 and refcount caches. The interval is in seconds.
1028 The default value is 600 on supporting platforms, and 0 on other platforms.
1029 Setting it to 0 disables this feature.
1031 @item pass-discard-request
1032 Whether discard requests to the qcow2 device should be forwarded to the data
1033 source (on/off; default: on if discard=unmap is specified, off otherwise)
1035 @item pass-discard-snapshot
1036 Whether discard requests for the data source should be issued when a snapshot
1037 operation (e.g. deleting a snapshot) frees clusters in the qcow2 file (on/off;
1040 @item pass-discard-other
1041 Whether discard requests for the data source should be issued on other
1042 occasions where a cluster gets freed (on/off; default: off)
1045 Which overlap checks to perform for writes to the image
1046 (none/constant/cached/all; default: cached). For details or finer
1047 granularity control refer to the QAPI documentation of @code{blockdev-add}.
1052 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1053 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1057 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1060 @item Driver-specific options for other drivers
1061 Please refer to the QAPI documentation of the @code{blockdev-add} QMP command.
1067 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1068 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1069 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1070 " [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1071 " [,werror=ignore|stop|report|enospc][,id=name][,aio=threads|native]\n"
1072 " [,readonly=on|off][,copy-on-read=on|off]\n"
1073 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1074 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1075 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1076 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1077 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1078 " [[,iops_size=is]]\n"
1080 " use 'file' as a drive image\n", QEMU_ARCH_ALL)
1082 @item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
1085 Define a new drive. This includes creating a block driver node (the backend) as
1086 well as a guest device, and is mostly a shortcut for defining the corresponding
1087 @option{-blockdev} and @option{-device} options.
1089 @option{-drive} accepts all options that are accepted by @option{-blockdev}. In
1090 addition, it knows the following options:
1093 @item file=@var{file}
1094 This option defines which disk image (@pxref{disk_images}) to use with
1095 this drive. If the filename contains comma, you must double it
1096 (for instance, "file=my,,file" to use file "my,file").
1098 Special files such as iSCSI devices can be specified using protocol
1099 specific URLs. See the section for "Device URL Syntax" for more information.
1100 @item if=@var{interface}
1101 This option defines on which type on interface the drive is connected.
1102 Available types are: ide, scsi, sd, mtd, floppy, pflash, virtio, none.
1103 @item bus=@var{bus},unit=@var{unit}
1104 These options define where is connected the drive by defining the bus number and
1106 @item index=@var{index}
1107 This option defines where is connected the drive by using an index in the list
1108 of available connectors of a given interface type.
1109 @item media=@var{media}
1110 This option defines the type of the media: disk or cdrom.
1111 @item snapshot=@var{snapshot}
1112 @var{snapshot} is "on" or "off" and controls snapshot mode for the given drive
1113 (see @option{-snapshot}).
1114 @item cache=@var{cache}
1115 @var{cache} is "none", "writeback", "unsafe", "directsync" or "writethrough"
1116 and controls how the host cache is used to access block data. This is a
1117 shortcut that sets the @option{cache.direct} and @option{cache.no-flush}
1118 options (as in @option{-blockdev}), and additionally @option{cache.writeback},
1119 which provides a default for the @option{write-cache} option of block guest
1120 devices (as in @option{-device}). The modes correspond to the following
1123 @c Our texi2pod.pl script doesn't support @multitable, so fall back to using
1124 @c plain ASCII art (well, UTF-8 art really). This looks okay both in the manpage
1125 @c and the HTML output.
1127 @ │ cache.writeback cache.direct cache.no-flush
1128 ─────────────┼─────────────────────────────────────────────────
1129 writeback │ on off off
1131 writethrough │ off off off
1132 directsync │ off on off
1133 unsafe │ on off on
1136 The default mode is @option{cache=writeback}.
1139 @var{aio} is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO.
1140 @item format=@var{format}
1141 Specify which disk @var{format} will be used rather than detecting
1142 the format. Can be used to specify format=raw to avoid interpreting
1143 an untrusted format header.
1144 @item werror=@var{action},rerror=@var{action}
1145 Specify which @var{action} to take on write and read errors. Valid actions are:
1146 "ignore" (ignore the error and try to continue), "stop" (pause QEMU),
1147 "report" (report the error to the guest), "enospc" (pause QEMU only if the
1148 host disk is full; report the error to the guest otherwise).
1149 The default setting is @option{werror=enospc} and @option{rerror=report}.
1150 @item copy-on-read=@var{copy-on-read}
1151 @var{copy-on-read} is "on" or "off" and enables whether to copy read backing
1152 file sectors into the image file.
1153 @item bps=@var{b},bps_rd=@var{r},bps_wr=@var{w}
1154 Specify bandwidth throttling limits in bytes per second, either for all request
1155 types or for reads or writes only. Small values can lead to timeouts or hangs
1156 inside the guest. A safe minimum for disks is 2 MB/s.
1157 @item bps_max=@var{bm},bps_rd_max=@var{rm},bps_wr_max=@var{wm}
1158 Specify bursts in bytes per second, either for all request types or for reads
1159 or writes only. Bursts allow the guest I/O to spike above the limit
1161 @item iops=@var{i},iops_rd=@var{r},iops_wr=@var{w}
1162 Specify request rate limits in requests per second, either for all request
1163 types or for reads or writes only.
1164 @item iops_max=@var{bm},iops_rd_max=@var{rm},iops_wr_max=@var{wm}
1165 Specify bursts in requests per second, either for all request types or for reads
1166 or writes only. Bursts allow the guest I/O to spike above the limit
1168 @item iops_size=@var{is}
1169 Let every @var{is} bytes of a request count as a new request for iops
1170 throttling purposes. Use this option to prevent guests from circumventing iops
1171 limits by sending fewer but larger requests.
1173 Join a throttling quota group with given name @var{g}. All drives that are
1174 members of the same group are accounted for together. Use this option to
1175 prevent guests from circumventing throttling limits by using many small disks
1176 instead of a single larger disk.
1179 By default, the @option{cache.writeback=on} mode is used. It will report data
1180 writes as completed as soon as the data is present in the host page cache.
1181 This is safe as long as your guest OS makes sure to correctly flush disk caches
1182 where needed. If your guest OS does not handle volatile disk write caches
1183 correctly and your host crashes or loses power, then the guest may experience
1186 For such guests, you should consider using @option{cache.writeback=off}. This
1187 means that the host page cache will be used to read and write data, but write
1188 notification will be sent to the guest only after QEMU has made sure to flush
1189 each write to the disk. Be aware that this has a major impact on performance.
1191 When using the @option{-snapshot} option, unsafe caching is always used.
1193 Copy-on-read avoids accessing the same backing file sectors repeatedly and is
1194 useful when the backing file is over a slow network. By default copy-on-read
1197 Instead of @option{-cdrom} you can use:
1199 @value{qemu_system} -drive file=file,index=2,media=cdrom
1202 Instead of @option{-hda}, @option{-hdb}, @option{-hdc}, @option{-hdd}, you can
1205 @value{qemu_system} -drive file=file,index=0,media=disk
1206 @value{qemu_system} -drive file=file,index=1,media=disk
1207 @value{qemu_system} -drive file=file,index=2,media=disk
1208 @value{qemu_system} -drive file=file,index=3,media=disk
1211 You can open an image using pre-opened file descriptors from an fd set:
1213 @value{qemu_system} \
1214 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
1215 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
1216 -drive file=/dev/fdset/2,index=0,media=disk
1219 You can connect a CDROM to the slave of ide0:
1221 @value{qemu_system_x86} -drive file=file,if=ide,index=1,media=cdrom
1224 If you don't specify the "file=" argument, you define an empty drive:
1226 @value{qemu_system_x86} -drive if=ide,index=1,media=cdrom
1229 Instead of @option{-fda}, @option{-fdb}, you can use:
1231 @value{qemu_system_x86} -drive file=file,index=0,if=floppy
1232 @value{qemu_system_x86} -drive file=file,index=1,if=floppy
1235 By default, @var{interface} is "ide" and @var{index} is automatically
1238 @value{qemu_system_x86} -drive file=a -drive file=b"
1240 is interpreted like:
1242 @value{qemu_system_x86} -hda a -hdb b
1246 DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1247 "-mtdblock file use 'file' as on-board Flash memory image\n",
1250 @item -mtdblock @var{file}
1252 Use @var{file} as on-board Flash memory image.
1255 DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1256 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1258 @item -sd @var{file}
1260 Use @var{file} as SecureDigital card image.
1263 DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
1264 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
1266 @item -pflash @var{file}
1268 Use @var{file} as a parallel flash image.
1271 DEF("snapshot", 0, QEMU_OPTION_snapshot,
1272 "-snapshot write to temporary files instead of disk image files\n",
1277 Write to temporary files instead of disk image files. In this case,
1278 the raw disk image you use is not written back. You can however force
1279 the write back by pressing @key{C-a s} (@pxref{disk_images}).
1282 DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1283 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1284 " [,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode]\n"
1285 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1286 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1287 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1288 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1289 " [[,throttling.iops-size=is]]\n"
1290 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly]\n"
1291 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly]\n"
1292 "-fsdev synth,id=id\n",
1297 @item -fsdev local,id=@var{id},path=@var{path},security_model=@var{security_model} [,writeout=@var{writeout}][,readonly][,fmode=@var{fmode}][,dmode=@var{dmode}] [,throttling.@var{option}=@var{value}[,throttling.@var{option}=@var{value}[,...]]]
1298 @itemx -fsdev proxy,id=@var{id},socket=@var{socket}[,writeout=@var{writeout}][,readonly]
1299 @itemx -fsdev proxy,id=@var{id},sock_fd=@var{sock_fd}[,writeout=@var{writeout}][,readonly]
1300 @itemx -fsdev synth,id=@var{id}[,readonly]
1302 Define a new file system device. Valid options are:
1305 Accesses to the filesystem are done by QEMU.
1307 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1309 Synthetic filesystem, only used by QTests.
1311 Specifies identifier for this device.
1312 @item path=@var{path}
1313 Specifies the export path for the file system device. Files under
1314 this path will be available to the 9p client on the guest.
1315 @item security_model=@var{security_model}
1316 Specifies the security model to be used for this export path.
1317 Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none".
1318 In "passthrough" security model, files are stored using the same
1319 credentials as they are created on the guest. This requires QEMU
1320 to run as root. In "mapped-xattr" security model, some of the file
1321 attributes like uid, gid, mode bits and link target are stored as
1322 file attributes. For "mapped-file" these attributes are stored in the
1323 hidden .virtfs_metadata directory. Directories exported by this security model cannot
1324 interact with other unix tools. "none" security model is same as
1325 passthrough except the sever won't report failures if it fails to
1326 set file attributes like ownership. Security model is mandatory
1327 only for local fsdriver. Other fsdrivers (like proxy) don't take
1328 security model as a parameter.
1329 @item writeout=@var{writeout}
1330 This is an optional argument. The only supported value is "immediate".
1331 This means that host page cache will be used to read and write data but
1332 write notification will be sent to the guest only when the data has been
1333 reported as written by the storage subsystem.
1335 Enables exporting 9p share as a readonly mount for guests. By default
1336 read-write access is given.
1337 @item socket=@var{socket}
1338 Enables proxy filesystem driver to use passed socket file for communicating
1339 with virtfs-proxy-helper(1).
1340 @item sock_fd=@var{sock_fd}
1341 Enables proxy filesystem driver to use passed socket descriptor for
1342 communicating with virtfs-proxy-helper(1). Usually a helper like libvirt
1343 will create socketpair and pass one of the fds as sock_fd.
1344 @item fmode=@var{fmode}
1345 Specifies the default mode for newly created files on the host. Works only
1346 with security models "mapped-xattr" and "mapped-file".
1347 @item dmode=@var{dmode}
1348 Specifies the default mode for newly created directories on the host. Works
1349 only with security models "mapped-xattr" and "mapped-file".
1350 @item throttling.bps-total=@var{b},throttling.bps-read=@var{r},throttling.bps-write=@var{w}
1351 Specify bandwidth throttling limits in bytes per second, either for all request
1352 types or for reads or writes only.
1353 @item throttling.bps-total-max=@var{bm},bps-read-max=@var{rm},bps-write-max=@var{wm}
1354 Specify bursts in bytes per second, either for all request types or for reads
1355 or writes only. Bursts allow the guest I/O to spike above the limit
1357 @item throttling.iops-total=@var{i},throttling.iops-read=@var{r}, throttling.iops-write=@var{w}
1358 Specify request rate limits in requests per second, either for all request
1359 types or for reads or writes only.
1360 @item throttling.iops-total-max=@var{im},throttling.iops-read-max=@var{irm}, throttling.iops-write-max=@var{iwm}
1361 Specify bursts in requests per second, either for all request types or for reads
1362 or writes only. Bursts allow the guest I/O to spike above the limit temporarily.
1363 @item throttling.iops-size=@var{is}
1364 Let every @var{is} bytes of a request count as a new request for iops
1365 throttling purposes.
1368 -fsdev option is used along with -device driver "virtio-9p-...".
1369 @item -device virtio-9p-@var{type},fsdev=@var{id},mount_tag=@var{mount_tag}
1370 Options for virtio-9p-... driver are:
1373 Specifies the variant to be used. Supported values are "pci", "ccw" or "device",
1374 depending on the machine type.
1375 @item fsdev=@var{id}
1376 Specifies the id value specified along with -fsdev option.
1377 @item mount_tag=@var{mount_tag}
1378 Specifies the tag name to be used by the guest to mount this export point.
1383 DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1384 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1385 " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1386 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly]\n"
1387 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly]\n"
1388 "-virtfs synth,mount_tag=tag[,id=id][,readonly]\n",
1393 @item -virtfs local,path=@var{path},mount_tag=@var{mount_tag} ,security_model=@var{security_model}[,writeout=@var{writeout}][,readonly] [,fmode=@var{fmode}][,dmode=@var{dmode}][,multidevs=@var{multidevs}]
1394 @itemx -virtfs proxy,socket=@var{socket},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly]
1395 @itemx -virtfs proxy,sock_fd=@var{sock_fd},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly]
1396 @itemx -virtfs synth,mount_tag=@var{mount_tag}
1399 Define a new filesystem device and expose it to the guest using a virtio-9p-device. The general form of a Virtual File system pass-through options are:
1402 Accesses to the filesystem are done by QEMU.
1404 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1406 Synthetic filesystem, only used by QTests.
1408 Specifies identifier for the filesystem device
1409 @item path=@var{path}
1410 Specifies the export path for the file system device. Files under
1411 this path will be available to the 9p client on the guest.
1412 @item security_model=@var{security_model}
1413 Specifies the security model to be used for this export path.
1414 Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none".
1415 In "passthrough" security model, files are stored using the same
1416 credentials as they are created on the guest. This requires QEMU
1417 to run as root. In "mapped-xattr" security model, some of the file
1418 attributes like uid, gid, mode bits and link target are stored as
1419 file attributes. For "mapped-file" these attributes are stored in the
1420 hidden .virtfs_metadata directory. Directories exported by this security model cannot
1421 interact with other unix tools. "none" security model is same as
1422 passthrough except the sever won't report failures if it fails to
1423 set file attributes like ownership. Security model is mandatory only
1424 for local fsdriver. Other fsdrivers (like proxy) don't take security
1425 model as a parameter.
1426 @item writeout=@var{writeout}
1427 This is an optional argument. The only supported value is "immediate".
1428 This means that host page cache will be used to read and write data but
1429 write notification will be sent to the guest only when the data has been
1430 reported as written by the storage subsystem.
1432 Enables exporting 9p share as a readonly mount for guests. By default
1433 read-write access is given.
1434 @item socket=@var{socket}
1435 Enables proxy filesystem driver to use passed socket file for
1436 communicating with virtfs-proxy-helper(1). Usually a helper like libvirt
1437 will create socketpair and pass one of the fds as sock_fd.
1439 Enables proxy filesystem driver to use passed 'sock_fd' as the socket
1440 descriptor for interfacing with virtfs-proxy-helper(1).
1441 @item fmode=@var{fmode}
1442 Specifies the default mode for newly created files on the host. Works only
1443 with security models "mapped-xattr" and "mapped-file".
1444 @item dmode=@var{dmode}
1445 Specifies the default mode for newly created directories on the host. Works
1446 only with security models "mapped-xattr" and "mapped-file".
1447 @item mount_tag=@var{mount_tag}
1448 Specifies the tag name to be used by the guest to mount this export point.
1449 @item multidevs=@var{multidevs}
1450 Specifies how to deal with multiple devices being shared with a 9p export.
1451 Supported behaviours are either "remap", "forbid" or "warn". The latter is
1452 the default behaviour on which virtfs 9p expects only one device to be
1453 shared with the same export, and if more than one device is shared and
1454 accessed via the same 9p export then only a warning message is logged
1455 (once) by qemu on host side. In order to avoid file ID collisions on guest
1456 you should either create a separate virtfs export for each device to be
1457 shared with guests (recommended way) or you might use "remap" instead which
1458 allows you to share multiple devices with only one export instead, which is
1459 achieved by remapping the original inode numbers from host to guest in a
1460 way that would prevent such collisions. Remapping inodes in such use cases
1461 is required because the original device IDs from host are never passed and
1462 exposed on guest. Instead all files of an export shared with virtfs always
1463 share the same device id on guest. So two files with identical inode
1464 numbers but from actually different devices on host would otherwise cause a
1465 file ID collision and hence potential misbehaviours on guest. "forbid" on
1466 the other hand assumes like "warn" that only one device is shared by the
1467 same export, however it will not only log a warning message but also
1468 deny access to additional devices on guest. Note though that "forbid" does
1469 currently not block all possible file access operations (e.g. readdir()
1470 would still return entries from other devices).
1474 DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
1475 "-iscsi [user=user][,password=password]\n"
1476 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
1477 " [,initiator-name=initiator-iqn][,id=target-iqn]\n"
1478 " [,timeout=timeout]\n"
1479 " iSCSI session parameters\n", QEMU_ARCH_ALL)
1484 Configure iSCSI session parameters.
1492 DEFHEADING(USB options:)
1497 DEF("usb", 0, QEMU_OPTION_usb,
1498 "-usb enable on-board USB host controller (if not enabled by default)\n",
1503 Enable USB emulation on machine types with an on-board USB host controller (if
1504 not enabled by default). Note that on-board USB host controllers may not
1505 support USB 3.0. In this case @option{-device qemu-xhci} can be used instead
1506 on machines with PCI.
1509 DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
1510 "-usbdevice name add the host or guest USB device 'name'\n",
1514 @item -usbdevice @var{devname}
1516 Add the USB device @var{devname}. Note that this option is deprecated,
1517 please use @code{-device usb-...} instead. @xref{usb_devices}.
1522 Virtual Mouse. This will override the PS/2 mouse emulation when activated.
1525 Pointer device that uses absolute coordinates (like a touchscreen). This
1526 means QEMU is able to report the mouse position without having to grab the
1527 mouse. Also overrides the PS/2 mouse emulation when activated.
1530 Braille device. This will use BrlAPI to display the braille output on a real
1541 DEFHEADING(Display options:)
1546 DEF("display", HAS_ARG, QEMU_OPTION_display,
1547 #if defined(CONFIG_SPICE)
1548 "-display spice-app[,gl=on|off]\n"
1550 #if defined(CONFIG_SDL)
1551 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off]\n"
1552 " [,window_close=on|off][,gl=on|core|es|off]\n"
1554 #if defined(CONFIG_GTK)
1555 "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
1557 #if defined(CONFIG_VNC)
1558 "-display vnc=<display>[,<optargs>]\n"
1560 #if defined(CONFIG_CURSES)
1561 "-display curses[,charset=<encoding>]\n"
1563 #if defined(CONFIG_OPENGL)
1564 "-display egl-headless[,rendernode=<file>]\n"
1567 " select display backend type\n"
1568 " The default display is equivalent to\n "
1569 #if defined(CONFIG_GTK)
1570 "\"-display gtk\"\n"
1571 #elif defined(CONFIG_SDL)
1572 "\"-display sdl\"\n"
1573 #elif defined(CONFIG_COCOA)
1574 "\"-display cocoa\"\n"
1575 #elif defined(CONFIG_VNC)
1576 "\"-vnc localhost:0,to=99,id=default\"\n"
1578 "\"-display none\"\n"
1582 @item -display @var{type}
1584 Select type of display to use. This option is a replacement for the
1585 old style -sdl/-curses/... options. Valid values for @var{type} are
1588 Display video output via SDL (usually in a separate graphics
1589 window; see the SDL documentation for other possibilities).
1591 Display video output via curses. For graphics device models which
1592 support a text mode, QEMU can display this output using a
1593 curses/ncurses interface. Nothing is displayed when the graphics
1594 device is in graphical mode or if the graphics device does not support
1595 a text mode. Generally only the VGA device models support text mode.
1596 The font charset used by the guest can be specified with the
1597 @code{charset} option, for example @code{charset=CP850} for IBM CP850
1598 encoding. The default is @code{CP437}.
1600 Do not display video output. The guest will still see an emulated
1601 graphics card, but its output will not be displayed to the QEMU
1602 user. This option differs from the -nographic option in that it
1603 only affects what is done with video output; -nographic also changes
1604 the destination of the serial and parallel port data.
1606 Display video output in a GTK window. This interface provides drop-down
1607 menus and other UI elements to configure and control the VM during
1610 Start a VNC server on display <arg>
1612 Offload all OpenGL operations to a local DRI device. For any graphical display,
1613 this display needs to be paired with either VNC or SPICE displays.
1615 Start QEMU as a Spice server and launch the default Spice client
1616 application. The Spice server will redirect the serial consoles and
1617 QEMU monitors. (Since 4.0)
1621 DEF("nographic", 0, QEMU_OPTION_nographic,
1622 "-nographic disable graphical output and redirect serial I/Os to console\n",
1627 Normally, if QEMU is compiled with graphical window support, it displays
1628 output such as guest graphics, guest console, and the QEMU monitor in a
1629 window. With this option, you can totally disable graphical output so
1630 that QEMU is a simple command line application. The emulated serial port
1631 is redirected on the console and muxed with the monitor (unless
1632 redirected elsewhere explicitly). Therefore, you can still use QEMU to
1633 debug a Linux kernel with a serial console. Use @key{C-a h} for help on
1634 switching between the console and monitor.
1637 DEF("curses", 0, QEMU_OPTION_curses,
1638 "-curses shorthand for -display curses\n",
1643 Normally, if QEMU is compiled with graphical window support, it displays
1644 output such as guest graphics, guest console, and the QEMU monitor in a
1645 window. With this option, QEMU can display the VGA output when in text
1646 mode using a curses/ncurses interface. Nothing is displayed in graphical
1650 DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
1651 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
1656 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that this also
1657 affects the special keys (for fullscreen, monitor-mode switching, etc).
1660 DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
1661 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
1666 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this also
1667 affects the special keys (for fullscreen, monitor-mode switching, etc).
1670 DEF("no-quit", 0, QEMU_OPTION_no_quit,
1671 "-no-quit disable SDL window close capability\n", QEMU_ARCH_ALL)
1675 Disable SDL window close capability.
1678 DEF("sdl", 0, QEMU_OPTION_sdl,
1679 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL)
1686 DEF("spice", HAS_ARG, QEMU_OPTION_spice,
1687 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
1688 " [,x509-key-file=<file>][,x509-key-password=<file>]\n"
1689 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
1690 " [,x509-dh-key-file=<file>][,addr=addr][,ipv4|ipv6|unix]\n"
1691 " [,tls-ciphers=<list>]\n"
1692 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
1693 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
1694 " [,sasl][,password=<secret>][,disable-ticketing]\n"
1695 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
1696 " [,jpeg-wan-compression=[auto|never|always]]\n"
1697 " [,zlib-glz-wan-compression=[auto|never|always]]\n"
1698 " [,streaming-video=[off|all|filter]][,disable-copy-paste]\n"
1699 " [,disable-agent-file-xfer][,agent-mouse=[on|off]]\n"
1700 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
1701 " [,gl=[on|off]][,rendernode=<file>]\n"
1703 " at least one of {port, tls-port} is mandatory\n",
1706 @item -spice @var{option}[,@var{option}[,...]]
1708 Enable the spice remote desktop protocol. Valid options are
1713 Set the TCP port spice is listening on for plaintext channels.
1716 Set the IP address spice is listening on. Default is any address.
1721 Force using the specified IP version.
1723 @item password=<secret>
1724 Set the password you need to authenticate.
1727 Require that the client use SASL to authenticate with the spice.
1728 The exact choice of authentication method used is controlled from the
1729 system / user's SASL configuration file for the 'qemu' service. This
1730 is typically found in /etc/sasl2/qemu.conf. If running QEMU as an
1731 unprivileged user, an environment variable SASL_CONF_PATH can be used
1732 to make it search alternate locations for the service config.
1733 While some SASL auth methods can also provide data encryption (eg GSSAPI),
1734 it is recommended that SASL always be combined with the 'tls' and
1735 'x509' settings to enable use of SSL and server certificates. This
1736 ensures a data encryption preventing compromise of authentication
1739 @item disable-ticketing
1740 Allow client connects without authentication.
1742 @item disable-copy-paste
1743 Disable copy paste between the client and the guest.
1745 @item disable-agent-file-xfer
1746 Disable spice-vdagent based file-xfer between the client and the guest.
1749 Set the TCP port spice is listening on for encrypted channels.
1751 @item x509-dir=<dir>
1752 Set the x509 file directory. Expects same filenames as -vnc $display,x509=$dir
1754 @item x509-key-file=<file>
1755 @itemx x509-key-password=<file>
1756 @itemx x509-cert-file=<file>
1757 @itemx x509-cacert-file=<file>
1758 @itemx x509-dh-key-file=<file>
1759 The x509 file names can also be configured individually.
1761 @item tls-ciphers=<list>
1762 Specify which ciphers to use.
1764 @item tls-channel=[main|display|cursor|inputs|record|playback]
1765 @itemx plaintext-channel=[main|display|cursor|inputs|record|playback]
1766 Force specific channel to be used with or without TLS encryption. The
1767 options can be specified multiple times to configure multiple
1768 channels. The special name "default" can be used to set the default
1769 mode. For channels which are not explicitly forced into one mode the
1770 spice client is allowed to pick tls/plaintext as he pleases.
1772 @item image-compression=[auto_glz|auto_lz|quic|glz|lz|off]
1773 Configure image compression (lossless).
1774 Default is auto_glz.
1776 @item jpeg-wan-compression=[auto|never|always]
1777 @itemx zlib-glz-wan-compression=[auto|never|always]
1778 Configure wan image compression (lossy for slow links).
1781 @item streaming-video=[off|all|filter]
1782 Configure video stream detection. Default is off.
1784 @item agent-mouse=[on|off]
1785 Enable/disable passing mouse events via vdagent. Default is on.
1787 @item playback-compression=[on|off]
1788 Enable/disable audio stream compression (using celt 0.5.1). Default is on.
1790 @item seamless-migration=[on|off]
1791 Enable/disable spice seamless migration. Default is off.
1794 Enable/disable OpenGL context. Default is off.
1796 @item rendernode=<file>
1797 DRM render node for OpenGL rendering. If not specified, it will pick
1798 the first available. (Since 2.9)
1803 DEF("portrait", 0, QEMU_OPTION_portrait,
1804 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n",
1809 Rotate graphical output 90 deg left (only PXA LCD).
1812 DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
1813 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n",
1816 @item -rotate @var{deg}
1818 Rotate graphical output some deg left (only PXA LCD).
1821 DEF("vga", HAS_ARG, QEMU_OPTION_vga,
1822 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
1823 " select video card type\n", QEMU_ARCH_ALL)
1825 @item -vga @var{type}
1827 Select type of VGA card to emulate. Valid values for @var{type} are
1830 Cirrus Logic GD5446 Video card. All Windows versions starting from
1831 Windows 95 should recognize and use this graphic card. For optimal
1832 performances, use 16 bit color depth in the guest and the host OS.
1833 (This card was the default before QEMU 2.2)
1835 Standard VGA card with Bochs VBE extensions. If your guest OS
1836 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if you want
1837 to use high resolution modes (>= 1280x1024x16) then you should use
1838 this option. (This card is the default since QEMU 2.2)
1840 VMWare SVGA-II compatible adapter. Use it if you have sufficiently
1841 recent XFree86/XOrg server or Windows guest with a driver for this
1844 QXL paravirtual graphic card. It is VGA compatible (including VESA
1845 2.0 VBE support). Works best with qxl guest drivers installed though.
1846 Recommended choice when using the spice protocol.
1848 (sun4m only) Sun TCX framebuffer. This is the default framebuffer for
1849 sun4m machines and offers both 8-bit and 24-bit colour depths at a
1850 fixed resolution of 1024x768.
1852 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit framebuffer
1853 for sun4m machines available in both 1024x768 (OpenBIOS) and 1152x900 (OBP)
1854 resolutions aimed at people wishing to run older Solaris versions.
1862 DEF("full-screen", 0, QEMU_OPTION_full_screen,
1863 "-full-screen start in full screen\n", QEMU_ARCH_ALL)
1866 @findex -full-screen
1867 Start in full screen.
1870 DEF("g", 1, QEMU_OPTION_g ,
1871 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n",
1872 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K)
1874 @item -g @var{width}x@var{height}[x@var{depth}]
1876 Set the initial graphical resolution and depth (PPC, SPARC only).
1879 DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
1880 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
1882 @item -vnc @var{display}[,@var{option}[,@var{option}[,...]]]
1884 Normally, if QEMU is compiled with graphical window support, it displays
1885 output such as guest graphics, guest console, and the QEMU monitor in a
1886 window. With this option, you can have QEMU listen on VNC display
1887 @var{display} and redirect the VGA display over the VNC session. It is
1888 very useful to enable the usb tablet device when using this option
1889 (option @option{-device usb-tablet}). When using the VNC display, you
1890 must use the @option{-k} parameter to set the keyboard layout if you are
1891 not using en-us. Valid syntax for the @var{display} is
1897 With this option, QEMU will try next available VNC @var{display}s, until the
1898 number @var{L}, if the origianlly defined "-vnc @var{display}" is not
1899 available, e.g. port 5900+@var{display} is already used by another
1900 application. By default, to=0.
1902 @item @var{host}:@var{d}
1904 TCP connections will only be allowed from @var{host} on display @var{d}.
1905 By convention the TCP port is 5900+@var{d}. Optionally, @var{host} can
1906 be omitted in which case the server will accept connections from any host.
1908 @item unix:@var{path}
1910 Connections will be allowed over UNIX domain sockets where @var{path} is the
1911 location of a unix socket to listen for connections on.
1915 VNC is initialized but not started. The monitor @code{change} command
1916 can be used to later start the VNC server.
1920 Following the @var{display} value there may be one or more @var{option} flags
1921 separated by commas. Valid options are
1927 Connect to a listening VNC client via a ``reverse'' connection. The
1928 client is specified by the @var{display}. For reverse network
1929 connections (@var{host}:@var{d},@code{reverse}), the @var{d} argument
1930 is a TCP port number, not a display number.
1934 Opens an additional TCP listening port dedicated to VNC Websocket connections.
1935 If a bare @var{websocket} option is given, the Websocket port is
1936 5700+@var{display}. An alternative port can be specified with the
1937 syntax @code{websocket}=@var{port}.
1939 If @var{host} is specified connections will only be allowed from this host.
1940 It is possible to control the websocket listen address independently, using
1941 the syntax @code{websocket}=@var{host}:@var{port}.
1943 If no TLS credentials are provided, the websocket connection runs in
1944 unencrypted mode. If TLS credentials are provided, the websocket connection
1945 requires encrypted client connections.
1949 Require that password based authentication is used for client connections.
1951 The password must be set separately using the @code{set_password} command in
1952 the @ref{pcsys_monitor}. The syntax to change your password is:
1953 @code{set_password <protocol> <password>} where <protocol> could be either
1956 If you would like to change <protocol> password expiration, you should use
1957 @code{expire_password <protocol> <expiration-time>} where expiration time could
1958 be one of the following options: now, never, +seconds or UNIX time of
1959 expiration, e.g. +60 to make password expire in 60 seconds, or 1335196800
1960 to make password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for this
1963 You can also use keywords "now" or "never" for the expiration time to
1964 allow <protocol> password to expire immediately or never expire.
1966 @item tls-creds=@var{ID}
1968 Provides the ID of a set of TLS credentials to use to secure the
1969 VNC server. They will apply to both the normal VNC server socket
1970 and the websocket socket (if enabled). Setting TLS credentials
1971 will cause the VNC server socket to enable the VeNCrypt auth
1972 mechanism. The credentials should have been previously created
1973 using the @option{-object tls-creds} argument.
1975 @item tls-authz=@var{ID}
1977 Provides the ID of the QAuthZ authorization object against which
1978 the client's x509 distinguished name will validated. This object is
1979 only resolved at time of use, so can be deleted and recreated on the
1980 fly while the VNC server is active. If missing, it will default
1985 Require that the client use SASL to authenticate with the VNC server.
1986 The exact choice of authentication method used is controlled from the
1987 system / user's SASL configuration file for the 'qemu' service. This
1988 is typically found in /etc/sasl2/qemu.conf. If running QEMU as an
1989 unprivileged user, an environment variable SASL_CONF_PATH can be used
1990 to make it search alternate locations for the service config.
1991 While some SASL auth methods can also provide data encryption (eg GSSAPI),
1992 it is recommended that SASL always be combined with the 'tls' and
1993 'x509' settings to enable use of SSL and server certificates. This
1994 ensures a data encryption preventing compromise of authentication
1995 credentials. See the @ref{vnc_security} section for details on using
1996 SASL authentication.
1998 @item sasl-authz=@var{ID}
2000 Provides the ID of the QAuthZ authorization object against which
2001 the client's SASL username will validated. This object is
2002 only resolved at time of use, so can be deleted and recreated on the
2003 fly while the VNC server is active. If missing, it will default
2008 Legacy method for enabling authorization of clients against the
2009 x509 distinguished name and SASL username. It results in the creation
2010 of two @code{authz-list} objects with IDs of @code{vnc.username} and
2011 @code{vnc.x509dname}. The rules for these objects must be configured
2012 with the HMP ACL commands.
2014 This option is deprecated and should no longer be used. The new
2015 @option{sasl-authz} and @option{tls-authz} options are a
2020 Enable lossy compression methods (gradient, JPEG, ...). If this
2021 option is set, VNC client may receive lossy framebuffer updates
2022 depending on its encoding settings. Enabling this option can save
2023 a lot of bandwidth at the expense of quality.
2027 Disable adaptive encodings. Adaptive encodings are enabled by default.
2028 An adaptive encoding will try to detect frequently updated screen regions,
2029 and send updates in these regions using a lossy encoding (like JPEG).
2030 This can be really helpful to save bandwidth when playing videos. Disabling
2031 adaptive encodings restores the original static behavior of encodings
2034 @item share=[allow-exclusive|force-shared|ignore]
2036 Set display sharing policy. 'allow-exclusive' allows clients to ask
2037 for exclusive access. As suggested by the rfb spec this is
2038 implemented by dropping other connections. Connecting multiple
2039 clients in parallel requires all clients asking for a shared session
2040 (vncviewer: -shared switch). This is the default. 'force-shared'
2041 disables exclusive client access. Useful for shared desktop sessions,
2042 where you don't want someone forgetting specify -shared disconnect
2043 everybody else. 'ignore' completely ignores the shared flag and
2044 allows everybody connect unconditionally. Doesn't conform to the rfb
2045 spec but is traditional QEMU behavior.
2049 Set keyboard delay, for key down and key up events, in milliseconds.
2050 Default is 10. Keyboards are low-bandwidth devices, so this slowdown
2051 can help the device and guest to keep up and not lose events in case
2052 events are arriving in bulk. Possible causes for the latter are flaky
2053 network connections, or scripts for automated testing.
2055 @item audiodev=@var{audiodev}
2057 Use the specified @var{audiodev} when the VNC client requests audio
2058 transmission. When not using an -audiodev argument, this option must
2059 be omitted, otherwise is must be present and specify a valid audiodev.
2067 ARCHHEADING(, QEMU_ARCH_I386)
2069 ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2074 DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2075 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n",
2080 Use it when installing Windows 2000 to avoid a disk full bug. After
2081 Windows 2000 is installed, you no longer need this option (this option
2082 slows down the IDE transfers).
2085 DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2086 "-no-fd-bootchk disable boot signature checking for floppy disks\n",
2089 @item -no-fd-bootchk
2090 @findex -no-fd-bootchk
2091 Disable boot signature checking for floppy disks in BIOS. May
2092 be needed to boot from old floppy disks.
2095 DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
2096 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2100 Disable ACPI (Advanced Configuration and Power Interface) support. Use
2101 it if your guest OS complains about ACPI problems (PC target machine
2105 DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
2106 "-no-hpet disable HPET\n", QEMU_ARCH_I386)
2110 Disable HPET support.
2113 DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2114 "-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"
2115 " ACPI table description\n", QEMU_ARCH_I386)
2117 @item -acpitable [sig=@var{str}][,rev=@var{n}][,oem_id=@var{str}][,oem_table_id=@var{str}][,oem_rev=@var{n}] [,asl_compiler_id=@var{str}][,asl_compiler_rev=@var{n}][,data=@var{file1}[:@var{file2}]...]
2119 Add ACPI table with specified header fields and context from specified files.
2120 For file=, take whole ACPI table from the specified files, including all
2121 ACPI headers (possible overridden by other options).
2122 For data=, only data
2123 portion of the table is used, all header information is specified in the
2125 If a SLIC table is supplied to QEMU, then the SLIC's oem_id and oem_table_id
2126 fields will override the same in the RSDT and the FADT (a.k.a. FACP), in order
2127 to ensure the field matches required by the Microsoft SLIC spec and the ACPI
2131 DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2132 "-smbios file=binary\n"
2133 " load SMBIOS entry from binary file\n"
2134 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2136 " specify SMBIOS type 0 fields\n"
2137 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2138 " [,uuid=uuid][,sku=str][,family=str]\n"
2139 " specify SMBIOS type 1 fields\n"
2140 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2141 " [,asset=str][,location=str]\n"
2142 " specify SMBIOS type 2 fields\n"
2143 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2145 " specify SMBIOS type 3 fields\n"
2146 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2147 " [,asset=str][,part=str]\n"
2148 " specify SMBIOS type 4 fields\n"
2149 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2150 " [,asset=str][,part=str][,speed=%d]\n"
2151 " specify SMBIOS type 17 fields\n",
2152 QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2154 @item -smbios file=@var{binary}
2156 Load SMBIOS entry from binary file.
2158 @item -smbios type=0[,vendor=@var{str}][,version=@var{str}][,date=@var{str}][,release=@var{%d.%d}][,uefi=on|off]
2159 Specify SMBIOS type 0 fields
2161 @item -smbios type=1[,manufacturer=@var{str}][,product=@var{str}][,version=@var{str}][,serial=@var{str}][,uuid=@var{uuid}][,sku=@var{str}][,family=@var{str}]
2162 Specify SMBIOS type 1 fields
2164 @item -smbios type=2[,manufacturer=@var{str}][,product=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,location=@var{str}]
2165 Specify SMBIOS type 2 fields
2167 @item -smbios type=3[,manufacturer=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,sku=@var{str}]
2168 Specify SMBIOS type 3 fields
2170 @item -smbios type=4[,sock_pfx=@var{str}][,manufacturer=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,part=@var{str}]
2171 Specify SMBIOS type 4 fields
2173 @item -smbios type=17[,loc_pfx=@var{str}][,bank=@var{str}][,manufacturer=@var{str}][,serial=@var{str}][,asset=@var{str}][,part=@var{str}][,speed=@var{%d}]
2174 Specify SMBIOS type 17 fields
2182 DEFHEADING(Network options:)
2187 DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2189 "-netdev user,id=str[,ipv4[=on|off]][,net=addr[/mask]][,host=addr]\n"
2190 " [,ipv6[=on|off]][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2191 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2192 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2193 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2195 "[,smb=dir[,smbserver=addr]]\n"
2197 " configure a user mode network backend with ID 'str',\n"
2198 " its DHCP server and optional services\n"
2201 "-netdev tap,id=str,ifname=name\n"
2202 " configure a host TAP network backend with ID 'str'\n"
2204 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2205 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2206 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2208 " configure a host TAP network backend with ID 'str'\n"
2209 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2210 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2211 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2212 " to deconfigure it\n"
2213 " use '[down]script=no' to disable script execution\n"
2214 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2216 " use 'fd=h' to connect to an already opened TAP interface\n"
2217 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2218 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2219 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2220 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2221 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2222 " use vhost=on to enable experimental in kernel accelerator\n"
2223 " (only has effect for virtio guests which use MSIX)\n"
2224 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2225 " use 'vhostfd=h' to connect to an already opened vhost net device\n"
2226 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2227 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2228 " use 'poll-us=n' to speciy the maximum number of microseconds that could be\n"
2229 " spent on busy polling for vhost net\n"
2230 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2231 " configure a host TAP network backend with ID 'str' that is\n"
2232 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2233 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2236 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2237 " [,rxsession=rxsession],txsession=txsession[,ipv6=on/off][,udp=on/off]\n"
2238 " [,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie]\n"
2239 " [,rxcookie=rxcookie][,offset=offset]\n"
2240 " configure a network backend with ID 'str' connected to\n"
2241 " an Ethernet over L2TPv3 pseudowire.\n"
2242 " Linux kernel 3.3+ as well as most routers can talk\n"
2243 " L2TPv3. This transport allows connecting a VM to a VM,\n"
2244 " VM to a router and even VM to Host. It is a nearly-universal\n"
2245 " standard (RFC3391). Note - this implementation uses static\n"
2246 " pre-configured tunnels (same as the Linux kernel).\n"
2247 " use 'src=' to specify source address\n"
2248 " use 'dst=' to specify destination address\n"
2249 " use 'udp=on' to specify udp encapsulation\n"
2250 " use 'srcport=' to specify source udp port\n"
2251 " use 'dstport=' to specify destination udp port\n"
2252 " use 'ipv6=on' to force v6\n"
2253 " L2TPv3 uses cookies to prevent misconfiguration as\n"
2254 " well as a weak security measure\n"
2255 " use 'rxcookie=0x012345678' to specify a rxcookie\n"
2256 " use 'txcookie=0x012345678' to specify a txcookie\n"
2257 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2258 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2259 " use 'pincounter=on' to work around broken counter handling in peer\n"
2260 " use 'offset=X' to add an extra offset between header and data\n"
2262 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2263 " configure a network backend to connect to another network\n"
2264 " using a socket connection\n"
2265 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2266 " configure a network backend to connect to a multicast maddr and port\n"
2267 " use 'localaddr=addr' to specify the host address to send packets from\n"
2268 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2269 " configure a network backend to connect to another network\n"
2270 " using an UDP tunnel\n"
2272 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2273 " configure a network backend to connect to port 'n' of a vde switch\n"
2274 " running on host and listening for incoming connections on 'socketpath'.\n"
2275 " Use group 'groupname' and mode 'octalmode' to change default\n"
2276 " ownership and permissions for communication port.\n"
2278 #ifdef CONFIG_NETMAP
2279 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2280 " attach to the existing netmap-enabled network interface 'name', or to a\n"
2281 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2282 " netmap device, defaults to '/dev/netmap')\n"
2285 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2286 " configure a vhost-user network, backed by a chardev 'dev'\n"
2288 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2289 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2290 DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2301 #ifdef CONFIG_NETMAP
2307 "socket][,option][,...][mac=macaddr]\n"
2308 " initialize an on-board / default host NIC (using MAC address\n"
2309 " macaddr) and connect it to the given host network backend\n"
2310 "-nic none use it alone to have zero network devices (the default is to\n"
2311 " provided a 'user' network connection)\n",
2313 DEF("net", HAS_ARG, QEMU_OPTION_net,
2314 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2315 " configure or create an on-board (or machine default) NIC and\n"
2316 " connect it to hub 0 (please use -nic unless you need a hub)\n"
2326 #ifdef CONFIG_NETMAP
2329 "socket][,option][,option][,...]\n"
2330 " old way to initialize a host network interface\n"
2331 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
2333 @item -nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]
2335 This option is a shortcut for configuring both the on-board (default) guest
2336 NIC hardware and the host network backend in one go. The host backend options
2337 are the same as with the corresponding @option{-netdev} options below.
2338 The guest NIC model can be set with @option{model=@var{modelname}}.
2339 Use @option{model=help} to list the available device types.
2340 The hardware MAC address can be set with @option{mac=@var{macaddr}}.
2342 The following two example do exactly the same, to show how @option{-nic} can
2343 be used to shorten the command line length (note that the e1000 is the default
2344 on i386, so the @option{model=e1000} parameter could even be omitted here, too):
2346 @value{qemu_system} -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
2347 @value{qemu_system} -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
2351 Indicate that no network devices should be configured. It is used to override
2352 the default configuration (default NIC with ``user'' host network backend)
2353 which is activated if no other networking options are provided.
2355 @item -netdev user,id=@var{id}[,@var{option}][,@var{option}][,...]
2357 Configure user mode host network backend which requires no administrator
2358 privilege to run. Valid options are:
2362 Assign symbolic name for use in monitor commands.
2364 @item ipv4=on|off and ipv6=on|off
2365 Specify that either IPv4 or IPv6 must be enabled. If neither is specified
2366 both protocols are enabled.
2368 @item net=@var{addr}[/@var{mask}]
2369 Set IP network address the guest will see. Optionally specify the netmask,
2370 either in the form a.b.c.d or as number of valid top-most bits. Default is
2373 @item host=@var{addr}
2374 Specify the guest-visible address of the host. Default is the 2nd IP in the
2375 guest network, i.e. x.x.x.2.
2377 @item ipv6-net=@var{addr}[/@var{int}]
2378 Set IPv6 network address the guest will see (default is fec0::/64). The
2379 network prefix is given in the usual hexadecimal IPv6 address
2380 notation. The prefix size is optional, and is given as the number of
2381 valid top-most bits (default is 64).
2383 @item ipv6-host=@var{addr}
2384 Specify the guest-visible IPv6 address of the host. Default is the 2nd IPv6 in
2385 the guest network, i.e. xxxx::2.
2387 @item restrict=on|off
2388 If this option is enabled, the guest will be isolated, i.e. it will not be
2389 able to contact the host and no guest IP packets will be routed over the host
2390 to the outside. This option does not affect any explicitly set forwarding rules.
2392 @item hostname=@var{name}
2393 Specifies the client hostname reported by the built-in DHCP server.
2395 @item dhcpstart=@var{addr}
2396 Specify the first of the 16 IPs the built-in DHCP server can assign. Default
2397 is the 15th to 31st IP in the guest network, i.e. x.x.x.15 to x.x.x.31.
2399 @item dns=@var{addr}
2400 Specify the guest-visible address of the virtual nameserver. The address must
2401 be different from the host address. Default is the 3rd IP in the guest network,
2404 @item ipv6-dns=@var{addr}
2405 Specify the guest-visible address of the IPv6 virtual nameserver. The address
2406 must be different from the host address. Default is the 3rd IP in the guest
2407 network, i.e. xxxx::3.
2409 @item dnssearch=@var{domain}
2410 Provides an entry for the domain-search list sent by the built-in
2411 DHCP server. More than one domain suffix can be transmitted by specifying
2412 this option multiple times. If supported, this will cause the guest to
2413 automatically try to append the given domain suffix(es) in case a domain name
2414 can not be resolved.
2418 @value{qemu_system} -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
2421 @item domainname=@var{domain}
2422 Specifies the client domain name reported by the built-in DHCP server.
2424 @item tftp=@var{dir}
2425 When using the user mode network stack, activate a built-in TFTP
2426 server. The files in @var{dir} will be exposed as the root of a TFTP server.
2427 The TFTP client on the guest must be configured in binary mode (use the command
2428 @code{bin} of the Unix TFTP client).
2430 @item tftp-server-name=@var{name}
2431 In BOOTP reply, broadcast @var{name} as the "TFTP server name" (RFC2132 option
2432 66). This can be used to advise the guest to load boot files or configurations
2433 from a different server than the host address.
2435 @item bootfile=@var{file}
2436 When using the user mode network stack, broadcast @var{file} as the BOOTP
2437 filename. In conjunction with @option{tftp}, this can be used to network boot
2438 a guest from a local directory.
2440 Example (using pxelinux):
2442 @value{qemu_system} -hda linux.img -boot n -device e1000,netdev=n1 \
2443 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
2446 @item smb=@var{dir}[,smbserver=@var{addr}]
2447 When using the user mode network stack, activate a built-in SMB
2448 server so that Windows OSes can access to the host files in @file{@var{dir}}
2449 transparently. The IP address of the SMB server can be set to @var{addr}. By
2450 default the 4th IP in the guest network is used, i.e. x.x.x.4.
2452 In the guest Windows OS, the line:
2456 must be added in the file @file{C:\WINDOWS\LMHOSTS} (for windows 9x/Me)
2457 or @file{C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS} (Windows NT/2000).
2459 Then @file{@var{dir}} can be accessed in @file{\\smbserver\qemu}.
2461 Note that a SAMBA server must be installed on the host OS.
2463 @item hostfwd=[tcp|udp]:[@var{hostaddr}]:@var{hostport}-[@var{guestaddr}]:@var{guestport}
2464 Redirect incoming TCP or UDP connections to the host port @var{hostport} to
2465 the guest IP address @var{guestaddr} on guest port @var{guestport}. If
2466 @var{guestaddr} is not specified, its value is x.x.x.15 (default first address
2467 given by the built-in DHCP server). By specifying @var{hostaddr}, the rule can
2468 be bound to a specific host interface. If no connection type is set, TCP is
2469 used. This option can be given multiple times.
2471 For example, to redirect host X11 connection from screen 1 to guest
2472 screen 0, use the following:
2476 @value{qemu_system} -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
2477 # this host xterm should open in the guest X11 server
2481 To redirect telnet connections from host port 5555 to telnet port on
2482 the guest, use the following:
2486 @value{qemu_system} -nic user,hostfwd=tcp::5555-:23
2487 telnet localhost 5555
2490 Then when you use on the host @code{telnet localhost 5555}, you
2491 connect to the guest telnet server.
2493 @item guestfwd=[tcp]:@var{server}:@var{port}-@var{dev}
2494 @itemx guestfwd=[tcp]:@var{server}:@var{port}-@var{cmd:command}
2495 Forward guest TCP connections to the IP address @var{server} on port @var{port}
2496 to the character device @var{dev} or to a program executed by @var{cmd:command}
2497 which gets spawned for each connection. This option can be given multiple times.
2499 You can either use a chardev directly and have that one used throughout QEMU's
2500 lifetime, like in the following example:
2503 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
2504 # the guest accesses it
2505 @value{qemu_system} -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
2508 Or you can execute a command on every TCP connection established by the guest,
2509 so that QEMU behaves similar to an inetd process for that virtual server:
2512 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
2513 # and connect the TCP stream to its stdin/stdout
2514 @value{qemu_system} -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
2519 @item -netdev tap,id=@var{id}[,fd=@var{h}][,ifname=@var{name}][,script=@var{file}][,downscript=@var{dfile}][,br=@var{bridge}][,helper=@var{helper}]
2520 Configure a host TAP network backend with ID @var{id}.
2522 Use the network script @var{file} to configure it and the network script
2523 @var{dfile} to deconfigure it. If @var{name} is not provided, the OS
2524 automatically provides one. The default network configure script is
2525 @file{/etc/qemu-ifup} and the default network deconfigure script is
2526 @file{/etc/qemu-ifdown}. Use @option{script=no} or @option{downscript=no}
2527 to disable script execution.
2529 If running QEMU as an unprivileged user, use the network helper
2530 @var{helper} to configure the TAP interface and attach it to the bridge.
2531 The default network helper executable is @file{/path/to/qemu-bridge-helper}
2532 and the default bridge device is @file{br0}.
2534 @option{fd}=@var{h} can be used to specify the handle of an already
2535 opened host TAP interface.
2540 #launch a QEMU instance with the default network script
2541 @value{qemu_system} linux.img -nic tap
2545 #launch a QEMU instance with two NICs, each one connected
2547 @value{qemu_system} linux.img \
2548 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \
2549 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
2553 #launch a QEMU instance with the default network helper to
2554 #connect a TAP device to bridge br0
2555 @value{qemu_system} linux.img -device virtio-net-pci,netdev=n1 \
2556 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
2559 @item -netdev bridge,id=@var{id}[,br=@var{bridge}][,helper=@var{helper}]
2560 Connect a host TAP network interface to a host bridge device.
2562 Use the network helper @var{helper} to configure the TAP interface and
2563 attach it to the bridge. The default network helper executable is
2564 @file{/path/to/qemu-bridge-helper} and the default bridge
2565 device is @file{br0}.
2570 #launch a QEMU instance with the default network helper to
2571 #connect a TAP device to bridge br0
2572 @value{qemu_system} linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
2576 #launch a QEMU instance with the default network helper to
2577 #connect a TAP device to bridge qemubr0
2578 @value{qemu_system} linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
2581 @item -netdev socket,id=@var{id}[,fd=@var{h}][,listen=[@var{host}]:@var{port}][,connect=@var{host}:@var{port}]
2583 This host network backend can be used to connect the guest's network to
2584 another QEMU virtual machine using a TCP socket connection. If @option{listen}
2585 is specified, QEMU waits for incoming connections on @var{port}
2586 (@var{host} is optional). @option{connect} is used to connect to
2587 another QEMU instance using the @option{listen} option. @option{fd}=@var{h}
2588 specifies an already opened TCP socket.
2592 # launch a first QEMU instance
2593 @value{qemu_system} linux.img \
2594 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2595 -netdev socket,id=n1,listen=:1234
2596 # connect the network of this instance to the network of the first instance
2597 @value{qemu_system} linux.img \
2598 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
2599 -netdev socket,id=n2,connect=127.0.0.1:1234
2602 @item -netdev socket,id=@var{id}[,fd=@var{h}][,mcast=@var{maddr}:@var{port}[,localaddr=@var{addr}]]
2604 Configure a socket host network backend to share the guest's network traffic
2605 with another QEMU virtual machines using a UDP multicast socket, effectively
2606 making a bus for every QEMU with same multicast address @var{maddr} and @var{port}.
2610 Several QEMU can be running on different hosts and share same bus (assuming
2611 correct multicast setup for these hosts).
2613 mcast support is compatible with User Mode Linux (argument @option{eth@var{N}=mcast}), see
2614 @url{http://user-mode-linux.sf.net}.
2616 Use @option{fd=h} to specify an already opened UDP multicast socket.
2621 # launch one QEMU instance
2622 @value{qemu_system} linux.img \
2623 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2624 -netdev socket,id=n1,mcast=230.0.0.1:1234
2625 # launch another QEMU instance on same "bus"
2626 @value{qemu_system} linux.img \
2627 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
2628 -netdev socket,id=n2,mcast=230.0.0.1:1234
2629 # launch yet another QEMU instance on same "bus"
2630 @value{qemu_system} linux.img \
2631 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \
2632 -netdev socket,id=n3,mcast=230.0.0.1:1234
2635 Example (User Mode Linux compat.):
2637 # launch QEMU instance (note mcast address selected is UML's default)
2638 @value{qemu_system} linux.img \
2639 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2640 -netdev socket,id=n1,mcast=239.192.168.1:1102
2642 /path/to/linux ubd0=/path/to/root_fs eth0=mcast
2645 Example (send packets from host's 1.2.3.4):
2647 @value{qemu_system} linux.img \
2648 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2649 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
2652 @item -netdev l2tpv3,id=@var{id},src=@var{srcaddr},dst=@var{dstaddr}[,srcport=@var{srcport}][,dstport=@var{dstport}],txsession=@var{txsession}[,rxsession=@var{rxsession}][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=@var{txcookie}][,rxcookie=@var{rxcookie}][,offset=@var{offset}]
2653 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3391) is a
2654 popular protocol to transport Ethernet (and other Layer 2) data frames between
2655 two systems. It is present in routers, firewalls and the Linux kernel
2656 (from version 3.3 onwards).
2658 This transport allows a VM to communicate to another VM, router or firewall directly.
2661 @item src=@var{srcaddr}
2662 source address (mandatory)
2663 @item dst=@var{dstaddr}
2664 destination address (mandatory)
2666 select udp encapsulation (default is ip).
2667 @item srcport=@var{srcport}
2669 @item dstport=@var{dstport}
2670 destination udp port.
2672 force v6, otherwise defaults to v4.
2673 @item rxcookie=@var{rxcookie}
2674 @itemx txcookie=@var{txcookie}
2675 Cookies are a weak form of security in the l2tpv3 specification.
2676 Their function is mostly to prevent misconfiguration. By default they are 32
2679 Set cookie size to 64 bit instead of the default 32
2681 Force a 'cut-down' L2TPv3 with no counter as in
2682 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
2684 Work around broken counter handling in peer. This may also help on
2685 networks which have packet reorder.
2686 @item offset=@var{offset}
2687 Add an extra offset between header and data
2690 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to the bridge br-lan
2691 on the remote Linux host 1.2.3.4:
2693 # Setup tunnel on linux host using raw ip as encapsulation
2695 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \
2696 encap udp udp_sport 16384 udp_dport 16384
2697 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \
2698 0xFFFFFFFF peer_session_id 0xFFFFFFFF
2699 ifconfig vmtunnel0 mtu 1500
2700 ifconfig vmtunnel0 up
2701 brctl addif br-lan vmtunnel0
2705 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
2707 @value{qemu_system} linux.img -device e1000,netdev=n1 \
2708 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
2712 @item -netdev vde,id=@var{id}[,sock=@var{socketpath}][,port=@var{n}][,group=@var{groupname}][,mode=@var{octalmode}]
2713 Configure VDE backend to connect to PORT @var{n} of a vde switch running on host and
2714 listening for incoming connections on @var{socketpath}. Use GROUP @var{groupname}
2715 and MODE @var{octalmode} to change default ownership and permissions for
2716 communication port. This option is only available if QEMU has been compiled
2717 with vde support enabled.
2722 vde_switch -F -sock /tmp/myswitch
2723 # launch QEMU instance
2724 @value{qemu_system} linux.img -nic vde,sock=/tmp/myswitch
2727 @item -netdev vhost-user,chardev=@var{id}[,vhostforce=on|off][,queues=n]
2729 Establish a vhost-user netdev, backed by a chardev @var{id}. The chardev should
2730 be a unix domain socket backed one. The vhost-user uses a specifically defined
2731 protocol to pass vhost ioctl replacement messages to an application on the other
2732 end of the socket. On non-MSIX guests, the feature can be forced with
2733 @var{vhostforce}. Use 'queues=@var{n}' to specify the number of queues to
2734 be created for multiqueue vhost-user.
2738 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
2739 -numa node,memdev=mem \
2740 -chardev socket,id=chr0,path=/path/to/socket \
2741 -netdev type=vhost-user,id=net0,chardev=chr0 \
2742 -device virtio-net-pci,netdev=net0
2745 @item -netdev hubport,id=@var{id},hubid=@var{hubid}[,netdev=@var{nd}]
2747 Create a hub port on the emulated hub with ID @var{hubid}.
2749 The hubport netdev lets you connect a NIC to a QEMU emulated hub instead of a
2750 single netdev. Alternatively, you can also connect the hubport to another
2751 netdev with ID @var{nd} by using the @option{netdev=@var{nd}} option.
2753 @item -net nic[,netdev=@var{nd}][,macaddr=@var{mac}][,model=@var{type}] [,name=@var{name}][,addr=@var{addr}][,vectors=@var{v}]
2755 Legacy option to configure or create an on-board (or machine default) Network
2756 Interface Card(NIC) and connect it either to the emulated hub with ID 0 (i.e.
2757 the default hub), or to the netdev @var{nd}.
2758 The NIC is an e1000 by default on the PC target. Optionally, the MAC address
2759 can be changed to @var{mac}, the device address set to @var{addr} (PCI cards
2760 only), and a @var{name} can be assigned for use in monitor commands.
2761 Optionally, for PCI cards, you can specify the number @var{v} of MSI-X vectors
2762 that the card should have; this option currently only affects virtio cards; set
2763 @var{v} = 0 to disable MSI-X. If no @option{-net} option is specified, a single
2764 NIC is created. QEMU can emulate several different models of network card.
2765 Use @code{-net nic,model=help} for a list of available devices for your target.
2767 @item -net user|tap|bridge|socket|l2tpv3|vde[,...][,name=@var{name}]
2768 Configure a host network backend (with the options corresponding to the same
2769 @option{-netdev} option) and connect it to the emulated hub 0 (the default
2770 hub). Use @var{name} to specify the name of the hub port.
2778 DEFHEADING(Character device options:)
2780 DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
2782 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2783 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n"
2784 " [,server][,nowait][,telnet][,websocket][,reconnect=seconds][,mux=on|off]\n"
2785 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
2786 "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,websocket][,reconnect=seconds]\n"
2787 " [,mux=on|off][,logfile=PATH][,logappend=on|off] (unix)\n"
2788 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
2789 " [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n"
2790 " [,logfile=PATH][,logappend=on|off]\n"
2791 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2792 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
2793 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2794 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
2795 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2796 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2798 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2799 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2801 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2802 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
2804 #ifdef CONFIG_BRLAPI
2805 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2807 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
2808 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
2809 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2810 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2812 #if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
2813 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2814 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2816 #if defined(CONFIG_SPICE)
2817 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
2818 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
2825 The general form of a character device option is:
2827 @item -chardev @var{backend},id=@var{id}[,mux=on|off][,@var{options}]
2848 The specific backend will determine the applicable options.
2850 Use @code{-chardev help} to print all available chardev backend types.
2852 All devices must have an id, which can be any string up to 127 characters long.
2853 It is used to uniquely identify this device in other command line directives.
2855 A character device may be used in multiplexing mode by multiple front-ends.
2856 Specify @option{mux=on} to enable this mode.
2857 A multiplexer is a "1:N" device, and here the "1" end is your specified chardev
2858 backend, and the "N" end is the various parts of QEMU that can talk to a chardev.
2859 If you create a chardev with @option{id=myid} and @option{mux=on}, QEMU will
2860 create a multiplexer with your specified ID, and you can then configure multiple
2861 front ends to use that chardev ID for their input/output. Up to four different
2862 front ends can be connected to a single multiplexed chardev. (Without
2863 multiplexing enabled, a chardev can only be used by a single front end.)
2864 For instance you could use this to allow a single stdio chardev to be used by
2865 two serial ports and the QEMU monitor:
2868 -chardev stdio,mux=on,id=char0 \
2869 -mon chardev=char0,mode=readline \
2870 -serial chardev:char0 \
2871 -serial chardev:char0
2874 You can have more than one multiplexer in a system configuration; for instance
2875 you could have a TCP port multiplexed between UART 0 and UART 1, and stdio
2876 multiplexed between the QEMU monitor and a parallel port:
2879 -chardev stdio,mux=on,id=char0 \
2880 -mon chardev=char0,mode=readline \
2881 -parallel chardev:char0 \
2882 -chardev tcp,...,mux=on,id=char1 \
2883 -serial chardev:char1 \
2884 -serial chardev:char1
2887 When you're using a multiplexed character device, some escape sequences are
2888 interpreted in the input. @xref{mux_keys, Keys in the character backend
2891 Note that some other command line options may implicitly create multiplexed
2892 character backends; for instance @option{-serial mon:stdio} creates a
2893 multiplexed stdio backend connected to the serial port and the QEMU monitor,
2894 and @option{-nographic} also multiplexes the console and the monitor to
2897 There is currently no support for multiplexing in the other direction
2898 (where a single QEMU front end takes input and output from multiple chardevs).
2900 Every backend supports the @option{logfile} option, which supplies the path
2901 to a file to record all data transmitted via the backend. The @option{logappend}
2902 option controls whether the log file will be truncated or appended to when
2907 The available backends are:
2910 @item -chardev null,id=@var{id}
2911 A void device. This device will not emit any data, and will drop any data it
2912 receives. The null backend does not take any options.
2914 @item -chardev socket,id=@var{id}[,@var{TCP options} or @var{unix options}][,server][,nowait][,telnet][,websocket][,reconnect=@var{seconds}][,tls-creds=@var{id}][,tls-authz=@var{id}]
2916 Create a two-way stream socket, which can be either a TCP or a unix socket. A
2917 unix socket will be created if @option{path} is specified. Behaviour is
2918 undefined if TCP options are specified for a unix socket.
2920 @option{server} specifies that the socket shall be a listening socket.
2922 @option{nowait} specifies that QEMU should not block waiting for a client to
2923 connect to a listening socket.
2925 @option{telnet} specifies that traffic on the socket should interpret telnet
2928 @option{websocket} specifies that the socket uses WebSocket protocol for
2931 @option{reconnect} sets the timeout for reconnecting on non-server sockets when
2932 the remote end goes away. qemu will delay this many seconds and then attempt
2933 to reconnect. Zero disables reconnecting, and is the default.
2935 @option{tls-creds} requests enablement of the TLS protocol for encryption,
2936 and specifies the id of the TLS credentials to use for the handshake. The
2937 credentials must be previously created with the @option{-object tls-creds}
2940 @option{tls-auth} provides the ID of the QAuthZ authorization object against
2941 which the client's x509 distinguished name will be validated. This object is
2942 only resolved at time of use, so can be deleted and recreated on the fly
2943 while the chardev server is active. If missing, it will default to denying
2946 TCP and unix socket options are given below:
2950 @item TCP options: port=@var{port}[,host=@var{host}][,to=@var{to}][,ipv4][,ipv6][,nodelay]
2952 @option{host} for a listening socket specifies the local address to be bound.
2953 For a connecting socket species the remote host to connect to. @option{host} is
2954 optional for listening sockets. If not specified it defaults to @code{0.0.0.0}.
2956 @option{port} for a listening socket specifies the local port to be bound. For a
2957 connecting socket specifies the port on the remote host to connect to.
2958 @option{port} can be given as either a port number or a service name.
2959 @option{port} is required.
2961 @option{to} is only relevant to listening sockets. If it is specified, and
2962 @option{port} cannot be bound, QEMU will attempt to bind to subsequent ports up
2963 to and including @option{to} until it succeeds. @option{to} must be specified
2966 @option{ipv4} and @option{ipv6} specify that either IPv4 or IPv6 must be used.
2967 If neither is specified the socket may use either protocol.
2969 @option{nodelay} disables the Nagle algorithm.
2971 @item unix options: path=@var{path}
2973 @option{path} specifies the local path of the unix socket. @option{path} is
2978 @item -chardev udp,id=@var{id}[,host=@var{host}],port=@var{port}[,localaddr=@var{localaddr}][,localport=@var{localport}][,ipv4][,ipv6]
2980 Sends all traffic from the guest to a remote host over UDP.
2982 @option{host} specifies the remote host to connect to. If not specified it
2983 defaults to @code{localhost}.
2985 @option{port} specifies the port on the remote host to connect to. @option{port}
2988 @option{localaddr} specifies the local address to bind to. If not specified it
2989 defaults to @code{0.0.0.0}.
2991 @option{localport} specifies the local port to bind to. If not specified any
2992 available local port will be used.
2994 @option{ipv4} and @option{ipv6} specify that either IPv4 or IPv6 must be used.
2995 If neither is specified the device may use either protocol.
2997 @item -chardev msmouse,id=@var{id}
2999 Forward QEMU's emulated msmouse events to the guest. @option{msmouse} does not
3002 @item -chardev vc,id=@var{id}[[,width=@var{width}][,height=@var{height}]][[,cols=@var{cols}][,rows=@var{rows}]]
3004 Connect to a QEMU text console. @option{vc} may optionally be given a specific
3007 @option{width} and @option{height} specify the width and height respectively of
3008 the console, in pixels.
3010 @option{cols} and @option{rows} specify that the console be sized to fit a text
3011 console with the given dimensions.
3013 @item -chardev ringbuf,id=@var{id}[,size=@var{size}]
3015 Create a ring buffer with fixed size @option{size}.
3016 @var{size} must be a power of two and defaults to @code{64K}.
3018 @item -chardev file,id=@var{id},path=@var{path}
3020 Log all traffic received from the guest to a file.
3022 @option{path} specifies the path of the file to be opened. This file will be
3023 created if it does not already exist, and overwritten if it does. @option{path}
3026 @item -chardev pipe,id=@var{id},path=@var{path}
3028 Create a two-way connection to the guest. The behaviour differs slightly between
3029 Windows hosts and other hosts:
3031 On Windows, a single duplex pipe will be created at
3032 @file{\\.pipe\@option{path}}.
3034 On other hosts, 2 pipes will be created called @file{@option{path}.in} and
3035 @file{@option{path}.out}. Data written to @file{@option{path}.in} will be
3036 received by the guest. Data written by the guest can be read from
3037 @file{@option{path}.out}. QEMU will not create these fifos, and requires them to
3040 @option{path} forms part of the pipe path as described above. @option{path} is
3043 @item -chardev console,id=@var{id}
3045 Send traffic from the guest to QEMU's standard output. @option{console} does not
3048 @option{console} is only available on Windows hosts.
3050 @item -chardev serial,id=@var{id},path=@option{path}
3052 Send traffic from the guest to a serial device on the host.
3054 On Unix hosts serial will actually accept any tty device,
3055 not only serial lines.
3057 @option{path} specifies the name of the serial device to open.
3059 @item -chardev pty,id=@var{id}
3061 Create a new pseudo-terminal on the host and connect to it. @option{pty} does
3062 not take any options.
3064 @option{pty} is not available on Windows hosts.
3066 @item -chardev stdio,id=@var{id}[,signal=on|off]
3067 Connect to standard input and standard output of the QEMU process.
3069 @option{signal} controls if signals are enabled on the terminal, that includes
3070 exiting QEMU with the key sequence @key{Control-c}. This option is enabled by
3071 default, use @option{signal=off} to disable it.
3073 @item -chardev braille,id=@var{id}
3075 Connect to a local BrlAPI server. @option{braille} does not take any options.
3077 @item -chardev tty,id=@var{id},path=@var{path}
3079 @option{tty} is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD and
3080 DragonFlyBSD hosts. It is an alias for @option{serial}.
3082 @option{path} specifies the path to the tty. @option{path} is required.
3084 @item -chardev parallel,id=@var{id},path=@var{path}
3085 @itemx -chardev parport,id=@var{id},path=@var{path}
3087 @option{parallel} is only available on Linux, FreeBSD and DragonFlyBSD hosts.
3089 Connect to a local parallel port.
3091 @option{path} specifies the path to the parallel port device. @option{path} is
3094 @item -chardev spicevmc,id=@var{id},debug=@var{debug},name=@var{name}
3096 @option{spicevmc} is only available when spice support is built in.
3098 @option{debug} debug level for spicevmc
3100 @option{name} name of spice channel to connect to
3102 Connect to a spice virtual machine channel, such as vdiport.
3104 @item -chardev spiceport,id=@var{id},debug=@var{debug},name=@var{name}
3106 @option{spiceport} is only available when spice support is built in.
3108 @option{debug} debug level for spicevmc
3110 @option{name} name of spice port to connect to
3112 Connect to a spice port, allowing a Spice client to handle the traffic
3113 identified by a name (preferably a fqdn).
3122 DEFHEADING(TPM device options:)
3124 DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3125 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3126 " use path to provide path to a character device; default is /dev/tpm0\n"
3127 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
3128 " not provided it will be searched for in /sys/class/misc/tpm?/device\n"
3129 "-tpmdev emulator,id=id,chardev=dev\n"
3130 " configure the TPM device using chardev backend\n",
3134 The general form of a TPM device option is:
3137 @item -tpmdev @var{backend},id=@var{id}[,@var{options}]
3140 The specific backend type will determine the applicable options.
3141 The @code{-tpmdev} option creates the TPM backend and requires a
3142 @code{-device} option that specifies the TPM frontend interface model.
3144 Use @code{-tpmdev help} to print all available TPM backend types.
3148 The available backends are:
3152 @item -tpmdev passthrough,id=@var{id},path=@var{path},cancel-path=@var{cancel-path}
3154 (Linux-host only) Enable access to the host's TPM using the passthrough
3157 @option{path} specifies the path to the host's TPM device, i.e., on
3158 a Linux host this would be @code{/dev/tpm0}.
3159 @option{path} is optional and by default @code{/dev/tpm0} is used.
3161 @option{cancel-path} specifies the path to the host TPM device's sysfs
3162 entry allowing for cancellation of an ongoing TPM command.
3163 @option{cancel-path} is optional and by default QEMU will search for the
3166 Some notes about using the host's TPM with the passthrough driver:
3168 The TPM device accessed by the passthrough driver must not be
3169 used by any other application on the host.
3171 Since the host's firmware (BIOS/UEFI) has already initialized the TPM,
3172 the VM's firmware (BIOS/UEFI) will not be able to initialize the
3173 TPM again and may therefore not show a TPM-specific menu that would
3174 otherwise allow the user to configure the TPM, e.g., allow the user to
3175 enable/disable or activate/deactivate the TPM.
3176 Further, if TPM ownership is released from within a VM then the host's TPM
3177 will get disabled and deactivated. To enable and activate the
3178 TPM again afterwards, the host has to be rebooted and the user is
3179 required to enter the firmware's menu to enable and activate the TPM.
3180 If the TPM is left disabled and/or deactivated most TPM commands will fail.
3182 To create a passthrough TPM use the following two options:
3184 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3186 Note that the @code{-tpmdev} id is @code{tpm0} and is referenced by
3187 @code{tpmdev=tpm0} in the device option.
3189 @item -tpmdev emulator,id=@var{id},chardev=@var{dev}
3191 (Linux-host only) Enable access to a TPM emulator using Unix domain socket based
3194 @option{chardev} specifies the unique ID of a character device backend that provides connection to the software TPM server.
3196 To create a TPM emulator backend device with chardev socket backend:
3199 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3212 DEFHEADING(Linux/Multiboot boot specific:)
3215 When using these options, you can use a given Linux or Multiboot
3216 kernel without installing it in the disk image. It can be useful
3217 for easier testing of various kernels.
3222 DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
3223 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
3225 @item -kernel @var{bzImage}
3227 Use @var{bzImage} as kernel image. The kernel can be either a Linux kernel
3228 or in multiboot format.
3231 DEF("append", HAS_ARG, QEMU_OPTION_append, \
3232 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
3234 @item -append @var{cmdline}
3236 Use @var{cmdline} as kernel command line
3239 DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
3240 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
3242 @item -initrd @var{file}
3244 Use @var{file} as initial ram disk.
3246 @item -initrd "@var{file1} arg=foo,@var{file2}"
3248 This syntax is only available with multiboot.
3250 Use @var{file1} and @var{file2} as modules and pass arg=foo as parameter to the
3254 DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
3255 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL)
3257 @item -dtb @var{file}
3259 Use @var{file} as a device tree binary (dtb) image and pass it to the kernel
3268 DEFHEADING(Debug/Expert options:)
3273 DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
3274 "-fw_cfg [name=]<name>,file=<file>\n"
3275 " add named fw_cfg entry with contents from file\n"
3276 "-fw_cfg [name=]<name>,string=<str>\n"
3277 " add named fw_cfg entry with contents from string\n",
3281 @item -fw_cfg [name=]@var{name},file=@var{file}
3283 Add named fw_cfg entry with contents from file @var{file}.
3285 @item -fw_cfg [name=]@var{name},string=@var{str}
3286 Add named fw_cfg entry with contents from string @var{str}.
3288 The terminating NUL character of the contents of @var{str} will not be
3289 included as part of the fw_cfg item data. To insert contents with
3290 embedded NUL characters, you have to use the @var{file} parameter.
3292 The fw_cfg entries are passed by QEMU through to the guest.
3296 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
3298 creates an fw_cfg entry named opt/com.mycompany/blob with contents
3303 DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
3304 "-serial dev redirect the serial port to char device 'dev'\n",
3307 @item -serial @var{dev}
3309 Redirect the virtual serial port to host character device
3310 @var{dev}. The default device is @code{vc} in graphical mode and
3311 @code{stdio} in non graphical mode.
3313 This option can be used several times to simulate up to 4 serial
3316 Use @code{-serial none} to disable all serial ports.
3318 Available character devices are:
3320 @item vc[:@var{W}x@var{H}]
3321 Virtual console. Optionally, a width and height can be given in pixel with
3325 It is also possible to specify width or height in characters:
3330 [Linux only] Pseudo TTY (a new PTY is automatically allocated)
3332 No device is allocated.
3335 @item chardev:@var{id}
3336 Use a named character device defined with the @code{-chardev} option.
3338 [Linux only] Use host tty, e.g. @file{/dev/ttyS0}. The host serial port
3339 parameters are set according to the emulated ones.
3340 @item /dev/parport@var{N}
3341 [Linux only, parallel port only] Use host parallel port
3342 @var{N}. Currently SPP and EPP parallel port features can be used.
3343 @item file:@var{filename}
3344 Write output to @var{filename}. No character can be read.
3346 [Unix only] standard input/output
3347 @item pipe:@var{filename}
3348 name pipe @var{filename}
3350 [Windows only] Use host serial port @var{n}
3351 @item udp:[@var{remote_host}]:@var{remote_port}[@@[@var{src_ip}]:@var{src_port}]
3352 This implements UDP Net Console.
3353 When @var{remote_host} or @var{src_ip} are not specified
3354 they default to @code{0.0.0.0}.
3355 When not using a specified @var{src_port} a random port is automatically chosen.
3357 If you just want a simple readonly console you can use @code{netcat} or
3358 @code{nc}, by starting QEMU with: @code{-serial udp::4555} and nc as:
3359 @code{nc -u -l -p 4555}. Any time QEMU writes something to that port it
3360 will appear in the netconsole session.
3362 If you plan to send characters back via netconsole or you want to stop
3363 and start QEMU a lot of times, you should have QEMU use the same
3364 source port each time by using something like @code{-serial
3365 udp::4555@@:4556} to QEMU. Another approach is to use a patched
3366 version of netcat which can listen to a TCP port and send and receive
3367 characters via udp. If you have a patched version of netcat which
3368 activates telnet remote echo and single char transfer, then you can
3369 use the following options to set up a netcat redirector to allow
3370 telnet on port 5555 to access the QEMU port.
3373 -serial udp::4555@@:4556
3374 @item netcat options:
3375 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
3376 @item telnet options:
3380 @item tcp:[@var{host}]:@var{port}[,@var{server}][,nowait][,nodelay][,reconnect=@var{seconds}]
3381 The TCP Net Console has two modes of operation. It can send the serial
3382 I/O to a location or wait for a connection from a location. By default
3383 the TCP Net Console is sent to @var{host} at the @var{port}. If you use
3384 the @var{server} option QEMU will wait for a client socket application
3385 to connect to the port before continuing, unless the @code{nowait}
3386 option was specified. The @code{nodelay} option disables the Nagle buffering
3387 algorithm. The @code{reconnect} option only applies if @var{noserver} is
3388 set, if the connection goes down it will attempt to reconnect at the
3389 given interval. If @var{host} is omitted, 0.0.0.0 is assumed. Only
3390 one TCP connection at a time is accepted. You can use @code{telnet} to
3391 connect to the corresponding character device.
3393 @item Example to send tcp console to 192.168.0.2 port 4444
3394 -serial tcp:192.168.0.2:4444
3395 @item Example to listen and wait on port 4444 for connection
3396 -serial tcp::4444,server
3397 @item Example to not wait and listen on ip 192.168.0.100 port 4444
3398 -serial tcp:192.168.0.100:4444,server,nowait
3401 @item telnet:@var{host}:@var{port}[,server][,nowait][,nodelay]
3402 The telnet protocol is used instead of raw tcp sockets. The options
3403 work the same as if you had specified @code{-serial tcp}. The
3404 difference is that the port acts like a telnet server or client using
3405 telnet option negotiation. This will also allow you to send the
3406 MAGIC_SYSRQ sequence if you use a telnet that supports sending the break
3407 sequence. Typically in unix telnet you do it with Control-] and then
3408 type "send break" followed by pressing the enter key.
3410 @item websocket:@var{host}:@var{port},server[,nowait][,nodelay]
3411 The WebSocket protocol is used instead of raw tcp socket. The port acts as
3412 a WebSocket server. Client mode is not supported.
3414 @item unix:@var{path}[,server][,nowait][,reconnect=@var{seconds}]
3415 A unix domain socket is used instead of a tcp socket. The option works the
3416 same as if you had specified @code{-serial tcp} except the unix domain socket
3417 @var{path} is used for connections.
3419 @item mon:@var{dev_string}
3420 This is a special option to allow the monitor to be multiplexed onto
3421 another serial port. The monitor is accessed with key sequence of
3422 @key{Control-a} and then pressing @key{c}.
3423 @var{dev_string} should be any one of the serial devices specified
3424 above. An example to multiplex the monitor onto a telnet server
3425 listening on port 4444 would be:
3427 @item -serial mon:telnet::4444,server,nowait
3429 When the monitor is multiplexed to stdio in this way, Ctrl+C will not terminate
3430 QEMU any more but will be passed to the guest instead.
3433 Braille device. This will use BrlAPI to display the braille output on a real
3437 Three button serial mouse. Configure the guest to use Microsoft protocol.
3441 DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
3442 "-parallel dev redirect the parallel port to char device 'dev'\n",
3445 @item -parallel @var{dev}
3447 Redirect the virtual parallel port to host device @var{dev} (same
3448 devices as the serial port). On Linux hosts, @file{/dev/parportN} can
3449 be used to use hardware devices connected on the corresponding host
3452 This option can be used several times to simulate up to 3 parallel
3455 Use @code{-parallel none} to disable all parallel ports.
3458 DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
3459 "-monitor dev redirect the monitor to char device 'dev'\n",
3462 @item -monitor @var{dev}
3464 Redirect the monitor to host device @var{dev} (same devices as the
3466 The default device is @code{vc} in graphical mode and @code{stdio} in
3468 Use @code{-monitor none} to disable the default monitor.
3470 DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
3471 "-qmp dev like -monitor but opens in 'control' mode\n",
3474 @item -qmp @var{dev}
3476 Like -monitor but opens in 'control' mode.
3478 DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
3479 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
3482 @item -qmp-pretty @var{dev}
3484 Like -qmp but uses pretty JSON formatting.
3487 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
3488 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
3490 @item -mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]
3492 Setup monitor on chardev @var{name}. @code{pretty} turns on JSON pretty printing
3493 easing human reading and debugging.
3496 DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
3497 "-debugcon dev redirect the debug console to char device 'dev'\n",
3500 @item -debugcon @var{dev}
3502 Redirect the debug console to host device @var{dev} (same devices as the
3503 serial port). The debug console is an I/O port which is typically port
3504 0xe9; writing to that I/O port sends output to this device.
3505 The default device is @code{vc} in graphical mode and @code{stdio} in
3509 DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
3510 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL)
3512 @item -pidfile @var{file}
3514 Store the QEMU process PID in @var{file}. It is useful if you launch QEMU
3518 DEF("singlestep", 0, QEMU_OPTION_singlestep, \
3519 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL)
3523 Run the emulation in single step mode.
3526 DEF("preconfig", 0, QEMU_OPTION_preconfig, \
3527 "--preconfig pause QEMU before machine is initialized (experimental)\n",
3532 Pause QEMU for interactive configuration before the machine is created,
3533 which allows querying and configuring properties that will affect
3534 machine initialization. Use QMP command 'x-exit-preconfig' to exit
3535 the preconfig state and move to the next state (i.e. run guest if -S
3536 isn't used or pause the second time if -S is used). This option is
3540 DEF("S", 0, QEMU_OPTION_S, \
3541 "-S freeze CPU at startup (use 'c' to start execution)\n",
3546 Do not start CPU at startup (you must type 'c' in the monitor).
3549 DEF("realtime", HAS_ARG, QEMU_OPTION_realtime,
3550 "-realtime [mlock=on|off]\n"
3551 " run qemu with realtime features\n"
3552 " mlock=on|off controls mlock support (default: on)\n",
3555 @item -realtime mlock=on|off
3557 Run qemu with realtime features.
3558 mlocking qemu and guest memory can be enabled via @option{mlock=on}
3559 (enabled by default).
3562 DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
3563 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
3564 " run qemu with overcommit hints\n"
3565 " mem-lock=on|off controls memory lock support (default: off)\n"
3566 " cpu-pm=on|off controls cpu power management (default: off)\n",
3569 @item -overcommit mem-lock=on|off
3570 @item -overcommit cpu-pm=on|off
3572 Run qemu with hints about host resource overcommit. The default is
3573 to assume that host overcommits all resources.
3575 Locking qemu and guest memory can be enabled via @option{mem-lock=on} (disabled
3576 by default). This works when host memory is not overcommitted and reduces the
3577 worst-case latency for guest. This is equivalent to @option{realtime}.
3579 Guest ability to manage power state of host cpus (increasing latency for other
3580 processes on the same host cpu, but decreasing latency for guest) can be
3581 enabled via @option{cpu-pm=on} (disabled by default). This works best when
3582 host CPU is not overcommitted. When used, host estimates of CPU cycle and power
3583 utilization will be incorrect, not taking into account guest idle time.
3586 DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
3587 "-gdb dev wait for gdb connection on 'dev'\n", QEMU_ARCH_ALL)
3589 @item -gdb @var{dev}
3591 Wait for gdb connection on device @var{dev} (@pxref{gdb_usage}). Typical
3592 connections will likely be TCP-based, but also UDP, pseudo TTY, or even
3593 stdio are reasonable use case. The latter is allowing to start QEMU from
3594 within gdb and establish the connection via a pipe:
3596 (gdb) target remote | exec @value{qemu_system} -gdb stdio ...
3600 DEF("s", 0, QEMU_OPTION_s, \
3601 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
3606 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
3607 (@pxref{gdb_usage}).
3610 DEF("d", HAS_ARG, QEMU_OPTION_d, \
3611 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n",
3614 @item -d @var{item1}[,...]
3616 Enable logging of specified items. Use '-d help' for a list of log items.
3619 DEF("D", HAS_ARG, QEMU_OPTION_D, \
3620 "-D logfile output log to logfile (default stderr)\n",
3623 @item -D @var{logfile}
3625 Output log in @var{logfile} instead of to stderr
3628 DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
3629 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
3632 @item -dfilter @var{range1}[,...]
3634 Filter debug output to that relevant to a range of target addresses. The filter
3635 spec can be either @var{start}+@var{size}, @var{start}-@var{size} or
3636 @var{start}..@var{end} where @var{start} @var{end} and @var{size} are the
3637 addresses and sizes required. For example:
3639 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
3641 Will dump output for any code in the 0x1000 sized block starting at 0x8000 and
3642 the 0x200 sized block starting at 0xffffffc000080000 and another 0x1000 sized
3643 block starting at 0xffffffc00005f000.
3646 DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
3647 "-seed number seed the pseudo-random number generator\n",
3650 @item -seed @var{number}
3652 Force the guest to use a deterministic pseudo-random number generator, seeded
3653 with @var{number}. This does not affect crypto routines within the host.
3656 DEF("L", HAS_ARG, QEMU_OPTION_L, \
3657 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n",
3662 Set the directory for the BIOS, VGA BIOS and keymaps.
3664 To list all the data directories, use @code{-L help}.
3667 DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
3668 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL)
3670 @item -bios @var{file}
3672 Set the filename for the BIOS.
3675 DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
3676 "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ALL)
3680 Enable KVM full virtualization support. This option is only available
3681 if KVM support is enabled when compiling.
3684 DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
3685 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL)
3686 DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
3687 "-xen-attach attach to existing xen domain\n"
3688 " libxl will use this when starting QEMU\n",
3690 DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
3691 "-xen-domid-restrict restrict set of available xen operations\n"
3692 " to specified domain id. (Does not affect\n"
3693 " xenpv machine type).\n",
3696 @item -xen-domid @var{id}
3698 Specify xen guest domain @var{id} (XEN only).
3701 Attach to existing xen domain.
3702 libxl will use this when starting QEMU (XEN only).
3703 @findex -xen-domid-restrict
3704 Restrict set of available xen operations to specified domain id (XEN only).
3707 DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
3708 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL)
3712 Exit instead of rebooting.
3715 DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
3716 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL)
3719 @findex -no-shutdown
3720 Don't exit QEMU on guest shutdown, but instead only stop the emulation.
3721 This allows for instance switching to monitor to commit changes to the
3725 DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
3726 "-loadvm [tag|id]\n" \
3727 " start right away with a saved state (loadvm in monitor)\n",
3730 @item -loadvm @var{file}
3732 Start right away with a saved state (@code{loadvm} in monitor)
3736 DEF("daemonize", 0, QEMU_OPTION_daemonize, \
3737 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
3742 Daemonize the QEMU process after initialization. QEMU will not detach from
3743 standard IO until it is ready to receive connections on any of its devices.
3744 This option is a useful way for external programs to launch QEMU without having
3745 to cope with initialization race conditions.
3748 DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
3749 "-option-rom rom load a file, rom, into the option ROM space\n",
3752 @item -option-rom @var{file}
3754 Load the contents of @var{file} as an option ROM.
3755 This option is useful to load things like EtherBoot.
3758 DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
3759 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
3760 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
3765 @item -rtc [base=utc|localtime|@var{datetime}][,clock=host|rt|vm][,driftfix=none|slew]
3767 Specify @option{base} as @code{utc} or @code{localtime} to let the RTC start at the current
3768 UTC or local time, respectively. @code{localtime} is required for correct date in
3769 MS-DOS or Windows. To start at a specific point in time, provide @var{datetime} in the
3770 format @code{2006-06-17T16:01:21} or @code{2006-06-17}. The default base is UTC.
3772 By default the RTC is driven by the host system time. This allows using of the
3773 RTC as accurate reference clock inside the guest, specifically if the host
3774 time is smoothly following an accurate external reference clock, e.g. via NTP.
3775 If you want to isolate the guest time from the host, you can set @option{clock}
3776 to @code{rt} instead, which provides a host monotonic clock if host support it.
3777 To even prevent the RTC from progressing during suspension, you can set @option{clock}
3778 to @code{vm} (virtual clock). @samp{clock=vm} is recommended especially in
3779 icount mode in order to preserve determinism; however, note that in icount mode
3780 the speed of the virtual clock is variable and can in general differ from the
3783 Enable @option{driftfix} (i386 targets only) if you experience time drift problems,
3784 specifically with Windows' ACPI HAL. This option will try to figure out how
3785 many timer interrupts were not processed by the Windows guest and will
3789 DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
3790 "-icount [shift=N|auto][,align=on|off][,sleep=on|off,rr=record|replay,rrfile=<filename>,rrsnapshot=<snapshot>]\n" \
3791 " enable virtual instruction counter with 2^N clock ticks per\n" \
3792 " instruction, enable aligning the host and virtual clocks\n" \
3793 " or disable real time cpu sleeping\n", QEMU_ARCH_ALL)
3795 @item -icount [shift=@var{N}|auto][,rr=record|replay,rrfile=@var{filename},rrsnapshot=@var{snapshot}]
3797 Enable virtual instruction counter. The virtual cpu will execute one
3798 instruction every 2^@var{N} ns of virtual time. If @code{auto} is specified
3799 then the virtual cpu speed will be automatically adjusted to keep virtual
3800 time within a few seconds of real time.
3802 When the virtual cpu is sleeping, the virtual time will advance at default
3803 speed unless @option{sleep=on|off} is specified.
3804 With @option{sleep=on|off}, the virtual time will jump to the next timer deadline
3805 instantly whenever the virtual cpu goes to sleep mode and will not advance
3806 if no timer is enabled. This behavior give deterministic execution times from
3807 the guest point of view.
3809 Note that while this option can give deterministic behavior, it does not
3810 provide cycle accurate emulation. Modern CPUs contain superscalar out of
3811 order cores with complex cache hierarchies. The number of instructions
3812 executed often has little or no correlation with actual performance.
3814 @option{align=on} will activate the delay algorithm which will try
3815 to synchronise the host clock and the virtual clock. The goal is to
3816 have a guest running at the real frequency imposed by the shift option.
3817 Whenever the guest clock is behind the host clock and if
3818 @option{align=on} is specified then we print a message to the user
3819 to inform about the delay.
3820 Currently this option does not work when @option{shift} is @code{auto}.
3821 Note: The sync algorithm will work for those shift values for which
3822 the guest clock runs ahead of the host clock. Typically this happens
3823 when the shift value is high (how high depends on the host machine).
3825 When @option{rr} option is specified deterministic record/replay is enabled.
3826 Replay log is written into @var{filename} file in record mode and
3827 read from this file in replay mode.
3829 Option rrsnapshot is used to create new vm snapshot named @var{snapshot}
3830 at the start of execution recording. In replay mode this option is used
3831 to load the initial VM state.
3834 DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
3835 "-watchdog model\n" \
3836 " enable virtual hardware watchdog [default=none]\n",
3839 @item -watchdog @var{model}
3841 Create a virtual hardware watchdog device. Once enabled (by a guest
3842 action), the watchdog must be periodically polled by an agent inside
3843 the guest or else the guest will be restarted. Choose a model for
3844 which your guest has drivers.
3846 The @var{model} is the model of hardware watchdog to emulate. Use
3847 @code{-watchdog help} to list available hardware models. Only one
3848 watchdog can be enabled for a guest.
3850 The following models may be available:
3853 iBASE 700 is a very simple ISA watchdog with a single timer.
3855 Intel 6300ESB I/O controller hub is a much more featureful PCI-based
3856 dual-timer watchdog.
3858 A virtual watchdog for s390x backed by the diagnose 288 hypercall
3859 (currently KVM only).
3863 DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
3864 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
3865 " action when watchdog fires [default=reset]\n",
3868 @item -watchdog-action @var{action}
3869 @findex -watchdog-action
3871 The @var{action} controls what QEMU will do when the watchdog timer
3874 @code{reset} (forcefully reset the guest).
3875 Other possible actions are:
3876 @code{shutdown} (attempt to gracefully shutdown the guest),
3877 @code{poweroff} (forcefully poweroff the guest),
3878 @code{inject-nmi} (inject a NMI into the guest),
3879 @code{pause} (pause the guest),
3880 @code{debug} (print a debug message and continue), or
3881 @code{none} (do nothing).
3883 Note that the @code{shutdown} action requires that the guest responds
3884 to ACPI signals, which it may not be able to do in the sort of
3885 situations where the watchdog would have expired, and thus
3886 @code{-watchdog-action shutdown} is not recommended for production use.
3891 @item -watchdog i6300esb -watchdog-action pause
3892 @itemx -watchdog ib700
3896 DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
3897 "-echr chr set terminal escape character instead of ctrl-a\n",
3901 @item -echr @var{numeric_ascii_value}
3903 Change the escape character used for switching to the monitor when using
3904 monitor and serial sharing. The default is @code{0x01} when using the
3905 @code{-nographic} option. @code{0x01} is equal to pressing
3906 @code{Control-a}. You can select a different character from the ascii
3907 control keys where 1 through 26 map to Control-a through Control-z. For
3908 instance you could use the either of the following to change the escape
3909 character to Control-t.
3916 DEF("show-cursor", 0, QEMU_OPTION_show_cursor, \
3917 "-show-cursor show cursor\n", QEMU_ARCH_ALL)
3920 @findex -show-cursor
3924 DEF("tb-size", HAS_ARG, QEMU_OPTION_tb_size, \
3925 "-tb-size n set TB size\n", QEMU_ARCH_ALL)
3927 @item -tb-size @var{n}
3929 Set TCG translation block cache size. Deprecated, use @samp{-accel tcg,tb-size=@var{n}}
3933 DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
3934 "-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]\n" \
3935 "-incoming rdma:host:port[,ipv4][,ipv6]\n" \
3936 "-incoming unix:socketpath\n" \
3937 " prepare for incoming migration, listen on\n" \
3938 " specified protocol and socket address\n" \
3939 "-incoming fd:fd\n" \
3940 "-incoming exec:cmdline\n" \
3941 " accept incoming migration on given file descriptor\n" \
3942 " or from given external command\n" \
3943 "-incoming defer\n" \
3944 " wait for the URI to be specified via migrate_incoming\n",
3947 @item -incoming tcp:[@var{host}]:@var{port}[,to=@var{maxport}][,ipv4][,ipv6]
3948 @itemx -incoming rdma:@var{host}:@var{port}[,ipv4][,ipv6]
3950 Prepare for incoming migration, listen on a given tcp port.
3952 @item -incoming unix:@var{socketpath}
3953 Prepare for incoming migration, listen on a given unix socket.
3955 @item -incoming fd:@var{fd}
3956 Accept incoming migration from a given filedescriptor.
3958 @item -incoming exec:@var{cmdline}
3959 Accept incoming migration as an output from specified external command.
3961 @item -incoming defer
3962 Wait for the URI to be specified via migrate_incoming. The monitor can
3963 be used to change settings (such as migration parameters) prior to issuing
3964 the migrate_incoming to allow the migration to begin.
3967 DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
3968 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL)
3970 @item -only-migratable
3971 @findex -only-migratable
3972 Only allow migratable devices. Devices will not be allowed to enter an
3976 DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
3977 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL)
3981 Don't create default devices. Normally, QEMU sets the default devices like serial
3982 port, parallel port, virtual console, monitor device, VGA adapter, floppy and
3983 CD-ROM drive and others. The @code{-nodefaults} option will disable all those
3988 DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
3989 "-chroot dir chroot to dir just before starting the VM\n",
3993 @item -chroot @var{dir}
3995 Immediately before starting guest execution, chroot to the specified
3996 directory. Especially useful in combination with -runas.
4000 DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
4001 "-runas user change to user id user just before starting the VM\n" \
4002 " user can be numeric uid:gid instead\n",
4006 @item -runas @var{user}
4008 Immediately before starting guest execution, drop root privileges, switching
4009 to the specified user.
4012 DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
4013 "-prom-env variable=value\n"
4014 " set OpenBIOS nvram variables\n",
4015 QEMU_ARCH_PPC | QEMU_ARCH_SPARC)
4017 @item -prom-env @var{variable}=@var{value}
4019 Set OpenBIOS nvram @var{variable} to given @var{value} (PPC, SPARC only).
4021 DEF("semihosting", 0, QEMU_OPTION_semihosting,
4022 "-semihosting semihosting mode\n",
4023 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4024 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
4027 @findex -semihosting
4028 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only).
4030 DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
4031 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
4032 " semihosting configuration\n",
4033 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4034 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
4036 @item -semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]
4037 @findex -semihosting-config
4038 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II only).
4040 @item target=@code{native|gdb|auto}
4041 Defines where the semihosting calls will be addressed, to QEMU (@code{native})
4042 or to GDB (@code{gdb}). The default is @code{auto}, which means @code{gdb}
4043 during debug sessions and @code{native} otherwise.
4044 @item chardev=@var{str1}
4045 Send the output to a chardev backend output for native or auto output when not in gdb
4046 @item arg=@var{str1},arg=@var{str2},...
4047 Allows the user to pass input arguments, and can be used multiple times to build
4048 up a list. The old-style @code{-kernel}/@code{-append} method of passing a
4049 command line is still supported for backward compatibility. If both the
4050 @code{--semihosting-config arg} and the @code{-kernel}/@code{-append} are
4051 specified, the former is passed to semihosting as it always takes precedence.
4054 DEF("old-param", 0, QEMU_OPTION_old_param,
4055 "-old-param old param mode\n", QEMU_ARCH_ARM)
4058 @findex -old-param (ARM)
4059 Old param mode (ARM only).
4062 DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
4063 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4064 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4065 " Enable seccomp mode 2 system call filter (default 'off').\n" \
4066 " use 'obsolete' to allow obsolete system calls that are provided\n" \
4067 " by the kernel, but typically no longer used by modern\n" \
4068 " C library implementations.\n" \
4069 " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
4070 " its privileges by blacklisting all set*uid|gid system calls.\n" \
4071 " The value 'children' will deny set*uid|gid system calls for\n" \
4072 " main QEMU process but will allow forks and execves to run unprivileged\n" \
4073 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4074 " blacklisting *fork and execve\n" \
4075 " use 'resourcecontrol' to disable process affinity and schedular priority\n",
4078 @item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}][,resourcecontrol=@var{string}]
4080 Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
4081 disable it. The default is 'off'.
4083 @item obsolete=@var{string}
4084 Enable Obsolete system calls
4085 @item elevateprivileges=@var{string}
4086 Disable set*uid|gid system calls
4087 @item spawn=@var{string}
4088 Disable *fork and execve
4089 @item resourcecontrol=@var{string}
4090 Disable process affinity and schedular priority
4094 DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
4095 "-readconfig <file>\n", QEMU_ARCH_ALL)
4097 @item -readconfig @var{file}
4099 Read device configuration from @var{file}. This approach is useful when you want to spawn
4100 QEMU process with many command line options but you don't want to exceed the command line
4103 DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
4104 "-writeconfig <file>\n"
4105 " read/write config file\n", QEMU_ARCH_ALL)
4107 @item -writeconfig @var{file}
4108 @findex -writeconfig
4109 Write device configuration to @var{file}. The @var{file} can be either filename to save
4110 command line and device configuration into file or dash @code{-}) character to print the
4111 output to stdout. This can be later used as input file for @code{-readconfig} option.
4114 DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4116 " do not load default user-provided config files at startup\n",
4119 @item -no-user-config
4120 @findex -no-user-config
4121 The @code{-no-user-config} option makes QEMU not load any of the user-provided
4122 config files on @var{sysconfdir}.
4125 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4126 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4127 " specify tracing options\n",
4130 HXCOMM This line is not accurate, as some sub-options are backend-specific but
4131 HXCOMM HX does not support conditional compilation of text.
4132 @item -trace [[enable=]@var{pattern}][,events=@var{file}][,file=@var{file}]
4134 @include qemu-option-trace.texi
4136 DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4137 "-plugin [file=]<file>[,arg=<string>]\n"
4141 @item -plugin file=@var{file}[,arg=@var{string}]
4147 @item file=@var{file}
4148 Load the given plugin from a shared library file.
4149 @item arg=@var{string}
4150 Argument string passed to the plugin. (Can be given multiple times.)
4155 DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4156 DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4159 DEF("enable-fips", 0, QEMU_OPTION_enablefips,
4160 "-enable-fips enable FIPS 140-2 compliance\n",
4165 @findex -enable-fips
4166 Enable FIPS 140-2 compliance mode.
4169 HXCOMM Deprecated by -accel tcg
4170 DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386)
4172 DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4173 "-msg timestamp[=on|off]\n"
4174 " change the format of messages\n"
4175 " on|off controls leading timestamps (default:on)\n",
4178 @item -msg timestamp[=on|off]
4180 prepend a timestamp to each log message.(default:on)
4183 DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
4184 "-dump-vmstate <file>\n"
4185 " Output vmstate information in JSON format to file.\n"
4186 " Use the scripts/vmstate-static-checker.py file to\n"
4187 " check for possible regressions in migration code\n"
4188 " by comparing two such vmstate dumps.\n",
4191 @item -dump-vmstate @var{file}
4192 @findex -dump-vmstate
4193 Dump json-encoded vmstate information for current machine type to file
4197 DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
4198 "-enable-sync-profile\n"
4199 " enable synchronization profiling\n",
4202 @item -enable-sync-profile
4203 @findex -enable-sync-profile
4204 Enable synchronization profiling.
4212 DEFHEADING(Generic object creation:)
4217 DEF("object", HAS_ARG, QEMU_OPTION_object,
4218 "-object TYPENAME[,PROP1=VALUE1,...]\n"
4219 " create a new object of type TYPENAME setting properties\n"
4220 " in the order they are specified. Note that the 'id'\n"
4221 " property must be set. These objects are placed in the\n"
4222 " '/objects' path.\n",
4225 @item -object @var{typename}[,@var{prop1}=@var{value1},...]
4227 Create a new object of type @var{typename} setting properties
4228 in the order they are specified. Note that the 'id'
4229 property must be set. These objects are placed in the
4234 @item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off},discard-data=@var{on|off},merge=@var{on|off},dump=@var{on|off},prealloc=@var{on|off},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},align=@var{align}
4236 Creates a memory file backend object, which can be used to back
4237 the guest RAM with huge pages.
4239 The @option{id} parameter is a unique ID that will be used to reference this
4240 memory region when configuring the @option{-numa} argument.
4242 The @option{size} option provides the size of the memory region, and accepts
4243 common suffixes, eg @option{500M}.
4245 The @option{mem-path} provides the path to either a shared memory or huge page
4248 The @option{share} boolean option determines whether the memory
4249 region is marked as private to QEMU, or shared. The latter allows
4250 a co-operating external process to access the QEMU memory region.
4252 The @option{share} is also required for pvrdma devices due to
4253 limitations in the RDMA API provided by Linux.
4255 Setting share=on might affect the ability to configure NUMA
4256 bindings for the memory backend under some circumstances, see
4257 Documentation/vm/numa_memory_policy.txt on the Linux kernel
4258 source tree for additional details.
4260 Setting the @option{discard-data} boolean option to @var{on}
4261 indicates that file contents can be destroyed when QEMU exits,
4262 to avoid unnecessarily flushing data to the backing file. Note
4263 that @option{discard-data} is only an optimization, and QEMU
4264 might not discard file contents if it aborts unexpectedly or is
4265 terminated using SIGKILL.
4267 The @option{merge} boolean option enables memory merge, also known as
4268 MADV_MERGEABLE, so that Kernel Samepage Merging will consider the pages for
4269 memory deduplication.
4271 Setting the @option{dump} boolean option to @var{off} excludes the memory from
4272 core dumps. This feature is also known as MADV_DONTDUMP.
4274 The @option{prealloc} boolean option enables memory preallocation.
4276 The @option{host-nodes} option binds the memory range to a list of NUMA host
4279 The @option{policy} option sets the NUMA policy to one of the following values:
4285 @item @var{preferred}
4286 prefer the given host node list for allocation
4289 restrict memory allocation to the given host node list
4291 @item @var{interleave}
4292 interleave memory allocations across the given host node list
4295 The @option{align} option specifies the base address alignment when
4296 QEMU mmap(2) @option{mem-path}, and accepts common suffixes, eg
4297 @option{2M}. Some backend store specified by @option{mem-path}
4298 requires an alignment different than the default one used by QEMU, eg
4299 the device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
4300 such cases, users can specify the required alignment via this option.
4302 The @option{pmem} option specifies whether the backing file specified
4303 by @option{mem-path} is in host persistent memory that can be accessed
4304 using the SNIA NVM programming model (e.g. Intel NVDIMM).
4305 If @option{pmem} is set to 'on', QEMU will take necessary operations to
4306 guarantee the persistence of its own writes to @option{mem-path}
4307 (e.g. in vNVDIMM label emulation and live migration).
4308 Also, we will map the backend-file with MAP_SYNC flag, which ensures the
4309 file metadata is in sync for @option{mem-path} in case of host crash
4310 or a power failure. MAP_SYNC requires support from both the host kernel
4311 (since Linux kernel 4.15) and the filesystem of @option{mem-path} mounted
4314 @item -object memory-backend-ram,id=@var{id},merge=@var{on|off},dump=@var{on|off},share=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave}
4316 Creates a memory backend object, which can be used to back the guest RAM.
4317 Memory backend objects offer more control than the @option{-m} option that is
4318 traditionally used to define guest RAM. Please refer to
4319 @option{memory-backend-file} for a description of the options.
4321 @item -object memory-backend-memfd,id=@var{id},merge=@var{on|off},dump=@var{on|off},share=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},seal=@var{on|off},hugetlb=@var{on|off},hugetlbsize=@var{size}
4323 Creates an anonymous memory file backend object, which allows QEMU to
4324 share the memory with an external process (e.g. when using
4325 vhost-user). The memory is allocated with memfd and optional
4326 sealing. (Linux only)
4328 The @option{seal} option creates a sealed-file, that will block
4329 further resizing the memory ('on' by default).
4331 The @option{hugetlb} option specify the file to be created resides in
4332 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction with
4333 the @option{hugetlb} option, the @option{hugetlbsize} option specify
4334 the hugetlb page size on systems that support multiple hugetlb page
4335 sizes (it must be a power of 2 value supported by the system).
4337 In some versions of Linux, the @option{hugetlb} option is incompatible
4338 with the @option{seal} option (requires at least Linux 4.16).
4340 Please refer to @option{memory-backend-file} for a description of the
4343 The @option{share} boolean option is @var{on} by default with memfd.
4345 @item -object rng-builtin,id=@var{id}
4347 Creates a random number generator backend which obtains entropy from
4348 QEMU builtin functions. The @option{id} parameter is a unique ID that
4349 will be used to reference this entropy backend from the @option{virtio-rng}
4350 device. By default, the @option{virtio-rng} device uses this RNG backend.
4352 @item -object rng-random,id=@var{id},filename=@var{/dev/random}
4354 Creates a random number generator backend which obtains entropy from
4355 a device on the host. The @option{id} parameter is a unique ID that
4356 will be used to reference this entropy backend from the @option{virtio-rng}
4357 device. The @option{filename} parameter specifies which file to obtain
4358 entropy from and if omitted defaults to @option{/dev/urandom}.
4360 @item -object rng-egd,id=@var{id},chardev=@var{chardevid}
4362 Creates a random number generator backend which obtains entropy from
4363 an external daemon running on the host. The @option{id} parameter is
4364 a unique ID that will be used to reference this entropy backend from
4365 the @option{virtio-rng} device. The @option{chardev} parameter is
4366 the unique ID of a character device backend that provides the connection
4369 @item -object tls-creds-anon,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/cred/dir},verify-peer=@var{on|off}
4371 Creates a TLS anonymous credentials object, which can be used to provide
4372 TLS support on network backends. The @option{id} parameter is a unique
4373 ID which network backends will use to access the credentials. The
4374 @option{endpoint} is either @option{server} or @option{client} depending
4375 on whether the QEMU network backend that uses the credentials will be
4376 acting as a client or as a server. If @option{verify-peer} is enabled
4377 (the default) then once the handshake is completed, the peer credentials
4378 will be verified, though this is a no-op for anonymous credentials.
4380 The @var{dir} parameter tells QEMU where to find the credential
4381 files. For server endpoints, this directory may contain a file
4382 @var{dh-params.pem} providing diffie-hellman parameters to use
4383 for the TLS server. If the file is missing, QEMU will generate
4384 a set of DH parameters at startup. This is a computationally
4385 expensive operation that consumes random pool entropy, so it is
4386 recommended that a persistent set of parameters be generated
4389 @item -object tls-creds-psk,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/keys/dir}[,username=@var{username}]
4391 Creates a TLS Pre-Shared Keys (PSK) credentials object, which can be used to provide
4392 TLS support on network backends. The @option{id} parameter is a unique
4393 ID which network backends will use to access the credentials. The
4394 @option{endpoint} is either @option{server} or @option{client} depending
4395 on whether the QEMU network backend that uses the credentials will be
4396 acting as a client or as a server. For clients only, @option{username}
4397 is the username which will be sent to the server. If omitted
4398 it defaults to ``qemu''.
4400 The @var{dir} parameter tells QEMU where to find the keys file.
4401 It is called ``@var{dir}/keys.psk'' and contains ``username:key''
4402 pairs. This file can most easily be created using the GnuTLS
4403 @code{psktool} program.
4405 For server endpoints, @var{dir} may also contain a file
4406 @var{dh-params.pem} providing diffie-hellman parameters to use
4407 for the TLS server. If the file is missing, QEMU will generate
4408 a set of DH parameters at startup. This is a computationally
4409 expensive operation that consumes random pool entropy, so it is
4410 recommended that a persistent set of parameters be generated
4413 @item -object tls-creds-x509,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/cred/dir},priority=@var{priority},verify-peer=@var{on|off},passwordid=@var{id}
4415 Creates a TLS anonymous credentials object, which can be used to provide
4416 TLS support on network backends. The @option{id} parameter is a unique
4417 ID which network backends will use to access the credentials. The
4418 @option{endpoint} is either @option{server} or @option{client} depending
4419 on whether the QEMU network backend that uses the credentials will be
4420 acting as a client or as a server. If @option{verify-peer} is enabled
4421 (the default) then once the handshake is completed, the peer credentials
4422 will be verified. With x509 certificates, this implies that the clients
4423 must be provided with valid client certificates too.
4425 The @var{dir} parameter tells QEMU where to find the credential
4426 files. For server endpoints, this directory may contain a file
4427 @var{dh-params.pem} providing diffie-hellman parameters to use
4428 for the TLS server. If the file is missing, QEMU will generate
4429 a set of DH parameters at startup. This is a computationally
4430 expensive operation that consumes random pool entropy, so it is
4431 recommended that a persistent set of parameters be generated
4434 For x509 certificate credentials the directory will contain further files
4435 providing the x509 certificates. The certificates must be stored
4436 in PEM format, in filenames @var{ca-cert.pem}, @var{ca-crl.pem} (optional),
4437 @var{server-cert.pem} (only servers), @var{server-key.pem} (only servers),
4438 @var{client-cert.pem} (only clients), and @var{client-key.pem} (only clients).
4440 For the @var{server-key.pem} and @var{client-key.pem} files which
4441 contain sensitive private keys, it is possible to use an encrypted
4442 version by providing the @var{passwordid} parameter. This provides
4443 the ID of a previously created @code{secret} object containing the
4444 password for decryption.
4446 The @var{priority} parameter allows to override the global default
4447 priority used by gnutls. This can be useful if the system administrator
4448 needs to use a weaker set of crypto priorities for QEMU without
4449 potentially forcing the weakness onto all applications. Or conversely
4450 if one wants wants a stronger default for QEMU than for all other
4451 applications, they can do this through this parameter. Its format is
4452 a gnutls priority string as described at
4453 @url{https://gnutls.org/manual/html_node/Priority-Strings.html}.
4455 @item -object filter-buffer,id=@var{id},netdev=@var{netdevid},interval=@var{t}[,queue=@var{all|rx|tx}][,status=@var{on|off}]
4457 Interval @var{t} can't be 0, this filter batches the packet delivery: all
4458 packets arriving in a given interval on netdev @var{netdevid} are delayed
4459 until the end of the interval. Interval is in microseconds.
4460 @option{status} is optional that indicate whether the netfilter is
4461 on (enabled) or off (disabled), the default status for netfilter will be 'on'.
4463 queue @var{all|rx|tx} is an option that can be applied to any netfilter.
4465 @option{all}: the filter is attached both to the receive and the transmit
4466 queue of the netdev (default).
4468 @option{rx}: the filter is attached to the receive queue of the netdev,
4469 where it will receive packets sent to the netdev.
4471 @option{tx}: the filter is attached to the transmit queue of the netdev,
4472 where it will receive packets sent by the netdev.
4474 @item -object filter-mirror,id=@var{id},netdev=@var{netdevid},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support]
4476 filter-mirror on netdev @var{netdevid},mirror net packet to chardev@var{chardevid}, if it has the vnet_hdr_support flag, filter-mirror will mirror packet with vnet_hdr_len.
4478 @item -object filter-redirector,id=@var{id},netdev=@var{netdevid},indev=@var{chardevid},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support]
4480 filter-redirector on netdev @var{netdevid},redirect filter's net packet to chardev
4481 @var{chardevid},and redirect indev's packet to filter.if it has the vnet_hdr_support flag,
4482 filter-redirector will redirect packet with vnet_hdr_len.
4483 Create a filter-redirector we need to differ outdev id from indev id, id can not
4484 be the same. we can just use indev or outdev, but at least one of indev or outdev
4485 need to be specified.
4487 @item -object filter-rewriter,id=@var{id},netdev=@var{netdevid},queue=@var{all|rx|tx},[vnet_hdr_support]
4489 Filter-rewriter is a part of COLO project.It will rewrite tcp packet to
4490 secondary from primary to keep secondary tcp connection,and rewrite
4491 tcp packet to primary from secondary make tcp packet can be handled by
4492 client.if it has the vnet_hdr_support flag, we can parse packet with vnet header.
4496 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4497 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4498 -object filter-rewriter,id=rew0,netdev=hn0,queue=all
4500 @item -object filter-dump,id=@var{id},netdev=@var{dev}[,file=@var{filename}][,maxlen=@var{len}]
4502 Dump the network traffic on netdev @var{dev} to the file specified by
4503 @var{filename}. At most @var{len} bytes (64k by default) per packet are stored.
4504 The file format is libpcap, so it can be analyzed with tools such as tcpdump
4507 @item -object colo-compare,id=@var{id},primary_in=@var{chardevid},secondary_in=@var{chardevid},outdev=@var{chardevid},iothread=@var{id}[,vnet_hdr_support][,notify_dev=@var{id}]
4509 Colo-compare gets packet from primary_in@var{chardevid} and secondary_in@var{chardevid}, than compare primary packet with
4510 secondary packet. If the packets are same, we will output primary
4511 packet to outdev@var{chardevid}, else we will notify colo-frame
4512 do checkpoint and send primary packet to outdev@var{chardevid}.
4513 In order to improve efficiency, we need to put the task of comparison
4514 in another thread. If it has the vnet_hdr_support flag, colo compare
4515 will send/recv packet with vnet_hdr_len.
4516 If you want to use Xen COLO, will need the notify_dev to notify Xen
4517 colo-frame to do checkpoint.
4519 we must use it with the help of filter-mirror and filter-redirector.
4526 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4527 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4528 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4529 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4530 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4531 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4532 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4533 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4534 -object iothread,id=iothread1
4535 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4536 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4537 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4538 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
4541 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4542 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4543 -chardev socket,id=red0,host=3.3.3.3,port=9003
4544 -chardev socket,id=red1,host=3.3.3.3,port=9004
4545 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4546 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4552 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4553 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4554 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4555 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4556 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4557 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4558 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4559 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4560 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait
4561 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4562 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4563 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4564 -object iothread,id=iothread1
4565 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1
4568 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4569 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4570 -chardev socket,id=red0,host=3.3.3.3,port=9003
4571 -chardev socket,id=red1,host=3.3.3.3,port=9004
4572 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4573 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4577 If you want to know the detail of above command line, you can read
4578 the colo-compare git log.
4580 @item -object cryptodev-backend-builtin,id=@var{id}[,queues=@var{queues}]
4582 Creates a cryptodev backend which executes crypto opreation from
4583 the QEMU cipher APIS. The @var{id} parameter is
4584 a unique ID that will be used to reference this cryptodev backend from
4585 the @option{virtio-crypto} device. The @var{queues} parameter is optional,
4586 which specify the queue number of cryptodev backend, the default of
4591 # @value{qemu_system} \
4593 -object cryptodev-backend-builtin,id=cryptodev0 \
4594 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
4598 @item -object cryptodev-vhost-user,id=@var{id},chardev=@var{chardevid}[,queues=@var{queues}]
4600 Creates a vhost-user cryptodev backend, backed by a chardev @var{chardevid}.
4601 The @var{id} parameter is a unique ID that will be used to reference this
4602 cryptodev backend from the @option{virtio-crypto} device.
4603 The chardev should be a unix domain socket backed one. The vhost-user uses
4604 a specifically defined protocol to pass vhost ioctl replacement messages
4605 to an application on the other end of the socket.
4606 The @var{queues} parameter is optional, which specify the queue number
4607 of cryptodev backend for multiqueue vhost-user, the default of @var{queues} is 1.
4611 # @value{qemu_system} \
4613 -chardev socket,id=chardev0,path=/path/to/socket \
4614 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \
4615 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
4619 @item -object secret,id=@var{id},data=@var{string},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]
4620 @item -object secret,id=@var{id},file=@var{filename},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]
4622 Defines a secret to store a password, encryption key, or some other sensitive
4623 data. The sensitive data can either be passed directly via the @var{data}
4624 parameter, or indirectly via the @var{file} parameter. Using the @var{data}
4625 parameter is insecure unless the sensitive data is encrypted.
4627 The sensitive data can be provided in raw format (the default), or base64.
4628 When encoded as JSON, the raw format only supports valid UTF-8 characters,
4629 so base64 is recommended for sending binary data. QEMU will convert from
4630 which ever format is provided to the format it needs internally. eg, an
4631 RBD password can be provided in raw format, even though it will be base64
4632 encoded when passed onto the RBD sever.
4634 For added protection, it is possible to encrypt the data associated with
4635 a secret using the AES-256-CBC cipher. Use of encryption is indicated
4636 by providing the @var{keyid} and @var{iv} parameters. The @var{keyid}
4637 parameter provides the ID of a previously defined secret that contains
4638 the AES-256 decryption key. This key should be 32-bytes long and be
4639 base64 encoded. The @var{iv} parameter provides the random initialization
4640 vector used for encryption of this particular secret and should be a
4641 base64 encrypted string of the 16-byte IV.
4643 The simplest (insecure) usage is to provide the secret inline
4647 # @value{qemu_system} -object secret,id=sec0,data=letmein,format=raw
4651 The simplest secure usage is to provide the secret via a file
4653 # printf "letmein" > mypasswd.txt
4654 # @value{qemu_system} -object secret,id=sec0,file=mypasswd.txt,format=raw
4656 For greater security, AES-256-CBC should be used. To illustrate usage,
4657 consider the openssl command line tool which can encrypt the data. Note
4658 that when encrypting, the plaintext must be padded to the cipher block
4659 size (32 bytes) using the standard PKCS#5/6 compatible padding algorithm.
4661 First a master key needs to be created in base64 encoding:
4664 # openssl rand -base64 32 > key.b64
4665 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"')
4668 Each secret to be encrypted needs to have a random initialization vector
4669 generated. These do not need to be kept secret
4672 # openssl rand -base64 16 > iv.b64
4673 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"')
4676 The secret to be defined can now be encrypted, in this case we're
4677 telling openssl to base64 encode the result, but it could be left
4678 as raw bytes if desired.
4681 # SECRET=$(printf "letmein" |
4682 openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
4685 When launching QEMU, create a master secret pointing to @code{key.b64}
4686 and specify that to be used to decrypt the user password. Pass the
4687 contents of @code{iv.b64} to the second secret
4690 # @value{qemu_system} \
4691 -object secret,id=secmaster0,format=base64,file=key.b64 \
4692 -object secret,id=sec0,keyid=secmaster0,format=base64,\
4693 data=$SECRET,iv=$(<iv.b64)
4696 @item -object sev-guest,id=@var{id},cbitpos=@var{cbitpos},reduced-phys-bits=@var{val},[sev-device=@var{string},policy=@var{policy},handle=@var{handle},dh-cert-file=@var{file},session-file=@var{file}]
4698 Create a Secure Encrypted Virtualization (SEV) guest object, which can be used
4699 to provide the guest memory encryption support on AMD processors.
4701 When memory encryption is enabled, one of the physical address bit (aka the
4702 C-bit) is utilized to mark if a memory page is protected. The @option{cbitpos}
4703 is used to provide the C-bit position. The C-bit position is Host family dependent
4704 hence user must provide this value. On EPYC, the value should be 47.
4706 When memory encryption is enabled, we loose certain bits in physical address space.
4707 The @option{reduced-phys-bits} is used to provide the number of bits we loose in
4708 physical address space. Similar to C-bit, the value is Host family dependent.
4709 On EPYC, the value should be 5.
4711 The @option{sev-device} provides the device file to use for communicating with
4712 the SEV firmware running inside AMD Secure Processor. The default device is
4713 '/dev/sev'. If hardware supports memory encryption then /dev/sev devices are
4714 created by CCP driver.
4716 The @option{policy} provides the guest policy to be enforced by the SEV firmware
4717 and restrict what configuration and operational commands can be performed on this
4718 guest by the hypervisor. The policy should be provided by the guest owner and is
4719 bound to the guest and cannot be changed throughout the lifetime of the guest.
4722 If guest @option{policy} allows sharing the key with another SEV guest then
4723 @option{handle} can be use to provide handle of the guest from which to share
4726 The @option{dh-cert-file} and @option{session-file} provides the guest owner's
4727 Public Diffie-Hillman key defined in SEV spec. The PDH and session parameters
4728 are used for establishing a cryptographic session with the guest owner to
4729 negotiate keys used for attestation. The file must be encoded in base64.
4731 e.g to launch a SEV guest
4733 # @value{qemu_system_x86} \
4735 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \
4736 -machine ...,memory-encryption=sev0
4742 @item -object authz-simple,id=@var{id},identity=@var{string}
4744 Create an authorization object that will control access to network services.
4746 The @option{identity} parameter is identifies the user and its format
4747 depends on the network service that authorization object is associated
4748 with. For authorizing based on TLS x509 certificates, the identity must
4749 be the x509 distinguished name. Note that care must be taken to escape
4750 any commas in the distinguished name.
4752 An example authorization object to validate a x509 distinguished name
4755 # @value{qemu_system} \
4757 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \
4761 Note the use of quotes due to the x509 distinguished name containing
4762 whitespace, and escaping of ','.
4764 @item -object authz-listfile,id=@var{id},filename=@var{path},refresh=@var{yes|no}
4766 Create an authorization object that will control access to network services.
4768 The @option{filename} parameter is the fully qualified path to a file
4769 containing the access control list rules in JSON format.
4771 An example set of rules that match against SASL usernames might look
4777 @{ "match": "fred", "policy": "allow", "format": "exact" @},
4778 @{ "match": "bob", "policy": "allow", "format": "exact" @},
4779 @{ "match": "danb", "policy": "deny", "format": "glob" @},
4780 @{ "match": "dan*", "policy": "allow", "format": "exact" @},
4786 When checking access the object will iterate over all the rules and
4787 the first rule to match will have its @option{policy} value returned
4788 as the result. If no rules match, then the default @option{policy}
4791 The rules can either be an exact string match, or they can use the
4792 simple UNIX glob pattern matching to allow wildcards to be used.
4794 If @option{refresh} is set to true the file will be monitored
4795 and automatically reloaded whenever its content changes.
4797 As with the @code{authz-simple} object, the format of the identity
4798 strings being matched depends on the network service, but is usually
4799 a TLS x509 distinguished name, or a SASL username.
4801 An example authorization object to validate a SASL username
4804 # @value{qemu_system} \
4806 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=yes
4810 @item -object authz-pam,id=@var{id},service=@var{string}
4812 Create an authorization object that will control access to network services.
4814 The @option{service} parameter provides the name of a PAM service to use
4815 for authorization. It requires that a file @code{/etc/pam.d/@var{service}}
4816 exist to provide the configuration for the @code{account} subsystem.
4818 An example authorization object to validate a TLS x509 distinguished
4819 name would look like:
4822 # @value{qemu_system} \
4824 -object authz-pam,id=auth0,service=qemu-vnc
4828 There would then be a corresponding config file for PAM at
4829 @code{/etc/pam.d/qemu-vnc} that contains:
4832 account requisite pam_listfile.so item=user sense=allow \
4833 file=/etc/qemu/vnc.allow
4836 Finally the @code{/etc/qemu/vnc.allow} file would contain
4837 the list of x509 distingished names that are permitted
4841 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
4844 @item -object iothread,id=@var{id},poll-max-ns=@var{poll-max-ns},poll-grow=@var{poll-grow},poll-shrink=@var{poll-shrink}
4846 Creates a dedicated event loop thread that devices can be assigned to. This is
4847 known as an IOThread. By default device emulation happens in vCPU threads or
4848 the main event loop thread. This can become a scalability bottleneck.
4849 IOThreads allow device emulation and I/O to run on other host CPUs.
4851 The @option{id} parameter is a unique ID that will be used to reference this
4852 IOThread from @option{-device ...,iothread=@var{id}}. Multiple devices can be
4853 assigned to an IOThread. Note that not all devices support an
4854 @option{iothread} parameter.
4856 The @code{query-iothreads} QMP command lists IOThreads and reports their thread
4857 IDs so that the user can configure host CPU pinning/affinity.
4859 IOThreads use an adaptive polling algorithm to reduce event loop latency.
4860 Instead of entering a blocking system call to monitor file descriptors and then
4861 pay the cost of being woken up when an event occurs, the polling algorithm
4862 spins waiting for events for a short time. The algorithm's default parameters
4863 are suitable for many cases but can be adjusted based on knowledge of the
4864 workload and/or host device latency.
4866 The @option{poll-max-ns} parameter is the maximum number of nanoseconds to busy
4867 wait for events. Polling can be disabled by setting this value to 0.
4869 The @option{poll-grow} parameter is the multiplier used to increase the polling
4870 time when the algorithm detects it is missing events due to not polling long
4873 The @option{poll-shrink} parameter is the divisor used to decrease the polling
4874 time when the algorithm detects it is spending too long polling without
4875 encountering events.
4877 The polling parameters can be modified at run-time using the @code{qom-set} command (where @code{iothread1} is the IOThread's @code{id}):
4880 (qemu) qom-set /objects/iothread1 poll-max-ns 100000
4888 HXCOMM This is the last statement. Insert new options before this line!
projects / qemu.git / blob