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 " vmport=on|off|auto controls emulation of vmport (default: auto)\n"
36 " dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
37 " mem-merge=on|off controls memory merge support (default: on)\n"
38 " aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n"
39 " dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n"
40 " suppress-vmdesc=on|off disables self-describing migration (default=off)\n"
41 " nvdimm=on|off controls NVDIMM support (default=off)\n"
42 " enforce-config-section=on|off enforce configuration section migration (default=off)\n"
43 " memory-encryption=@var{} memory encryption object to use (default=none)\n"
44 " hmat=on|off controls ACPI HMAT support (default=off)\n",
47 @item -machine [type=]@var{name}[,prop=@var{value}[,...]]
49 Select the emulated machine by @var{name}. Use @code{-machine help} to list
52 For architectures which aim to support live migration compatibility
53 across releases, each release will introduce a new versioned machine
54 type. For example, the 2.8.0 release introduced machine types
55 ``pc-i440fx-2.8'' and ``pc-q35-2.8'' for the x86_64/i686 architectures.
57 To allow live migration of guests from QEMU version 2.8.0, to QEMU
58 version 2.9.0, the 2.9.0 version must support the ``pc-i440fx-2.8''
59 and ``pc-q35-2.8'' machines too. To allow users live migrating VMs
60 to skip multiple intermediate releases when upgrading, new releases
61 of QEMU will support machine types from many previous versions.
63 Supported machine properties are:
65 @item accel=@var{accels1}[:@var{accels2}[:...]]
66 This is used to enable an accelerator. Depending on the target architecture,
67 kvm, xen, hax, hvf, whpx or tcg can be available. By default, tcg is used. If there is
68 more than one accelerator specified, the next one is used if the previous one
70 @item vmport=on|off|auto
71 Enables emulation of VMWare IO port, for vmmouse etc. auto says to select the
72 value based on accel. For accel=xen the default is off otherwise the default
74 @item dump-guest-core=on|off
75 Include guest memory in a core dump. The default is on.
76 @item mem-merge=on|off
77 Enables or disables memory merge support. This feature, when supported by
78 the host, de-duplicates identical memory pages among VMs instances
80 @item aes-key-wrap=on|off
81 Enables or disables AES key wrapping support on s390-ccw hosts. This feature
82 controls whether AES wrapping keys will be created to allow
83 execution of AES cryptographic functions. The default is on.
84 @item dea-key-wrap=on|off
85 Enables or disables DEA key wrapping support on s390-ccw hosts. This feature
86 controls whether DEA wrapping keys will be created to allow
87 execution of DEA cryptographic functions. The default is on.
89 Enables or disables NVDIMM support. The default is off.
90 @item enforce-config-section=on|off
91 If @option{enforce-config-section} is set to @var{on}, force migration
92 code to send configuration section even if the machine-type sets the
93 @option{migration.send-configuration} property to @var{off}.
94 NOTE: this parameter is deprecated. Please use @option{-global}
95 @option{migration.send-configuration}=@var{on|off} instead.
96 @item memory-encryption=@var{}
97 Memory encryption object to use. The default is none.
99 Enables or disables ACPI Heterogeneous Memory Attribute Table (HMAT) support.
104 HXCOMM Deprecated by -machine
105 DEF("M", HAS_ARG, QEMU_OPTION_M, "", QEMU_ARCH_ALL)
107 DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
108 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL)
110 @item -cpu @var{model}
112 Select CPU model (@code{-cpu help} for list and additional feature selection)
115 DEF("accel", HAS_ARG, QEMU_OPTION_accel,
116 "-accel [accel=]accelerator[,prop[=value][,...]]\n"
117 " select accelerator (kvm, xen, hax, hvf, whpx or tcg; use 'help' for a list)\n"
118 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
119 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
120 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
121 " tb-size=n (TCG translation block cache size)\n"
122 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
124 @item -accel @var{name}[,prop=@var{value}[,...]]
126 This is used to enable an accelerator. Depending on the target architecture,
127 kvm, xen, hax, hvf, whpx or tcg can be available. By default, tcg is used. If there is
128 more than one accelerator specified, the next one is used if the previous one
131 @item igd-passthru=on|off
132 When Xen is in use, this option controls whether Intel integrated graphics
133 devices can be passed through to the guest (default=off)
134 @item kernel-irqchip=on|off|split
135 Controls KVM in-kernel irqchip support. The default is full acceleration of the
136 interrupt controllers. On x86, split irqchip reduces the kernel attack
137 surface, at a performance cost for non-MSI interrupts. Disabling the in-kernel
138 irqchip completely is not recommended except for debugging purposes.
139 @item kvm-shadow-mem=size
140 Defines the size of the KVM shadow MMU.
141 @item tb-size=@var{n}
142 Controls the size (in MiB) of the TCG translation block cache.
143 @item thread=single|multi
144 Controls number of TCG threads. When the TCG is multi-threaded there will be one
145 thread per vCPU therefor taking advantage of additional host cores. The default
146 is to enable multi-threading where both the back-end and front-ends support it and
147 no incompatible TCG features have been enabled (e.g. icount/replay).
151 DEF("smp", HAS_ARG, QEMU_OPTION_smp,
152 "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n"
153 " set the number of CPUs to 'n' [default=1]\n"
154 " maxcpus= maximum number of total cpus, including\n"
155 " offline CPUs for hotplug, etc\n"
156 " cores= number of CPU cores on one socket (for PC, it's on one die)\n"
157 " threads= number of threads on one CPU core\n"
158 " dies= number of CPU dies on one socket (for PC only)\n"
159 " sockets= number of discrete sockets in the system\n",
162 @item -smp [cpus=]@var{n}[,cores=@var{cores}][,threads=@var{threads}][,dies=dies][,sockets=@var{sockets}][,maxcpus=@var{maxcpus}]
164 Simulate an SMP system with @var{n} CPUs. On the PC target, up to 255
165 CPUs are supported. On Sparc32 target, Linux limits the number of usable CPUs
167 For the PC target, the number of @var{cores} per die, the number of @var{threads}
168 per cores, the number of @var{dies} per packages and the total number of
169 @var{sockets} can be specified. Missing values will be computed.
170 If any on the three values is given, the total number of CPUs @var{n} can be omitted.
171 @var{maxcpus} specifies the maximum number of hotpluggable CPUs.
174 DEF("numa", HAS_ARG, QEMU_OPTION_numa,
175 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
176 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
177 "-numa dist,src=source,dst=destination,val=distance\n"
178 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n",
181 @item -numa node[,mem=@var{size}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
182 @itemx -numa node[,memdev=@var{id}][,cpus=@var{firstcpu}[-@var{lastcpu}]][,nodeid=@var{node}][,initiator=@var{initiator}]
183 @itemx -numa dist,src=@var{source},dst=@var{destination},val=@var{distance}
184 @itemx -numa cpu,node-id=@var{node}[,socket-id=@var{x}][,core-id=@var{y}][,thread-id=@var{z}]
186 Define a NUMA node and assign RAM and VCPUs to it.
187 Set the NUMA distance from a source node to a destination node.
189 Legacy VCPU assignment uses @samp{cpus} option where
190 @var{firstcpu} and @var{lastcpu} are CPU indexes. Each
191 @samp{cpus} option represent a contiguous range of CPU indexes
192 (or a single VCPU if @var{lastcpu} is omitted). A non-contiguous
193 set of VCPUs can be represented by providing multiple @samp{cpus}
194 options. If @samp{cpus} is omitted on all nodes, VCPUs are automatically
197 For example, the following option assigns VCPUs 0, 1, 2 and 5 to
200 -numa node,cpus=0-2,cpus=5
203 @samp{cpu} option is a new alternative to @samp{cpus} option
204 which uses @samp{socket-id|core-id|thread-id} properties to assign
205 CPU objects to a @var{node} using topology layout properties of CPU.
206 The set of properties is machine specific, and depends on used
207 machine type/@samp{smp} options. It could be queried with
208 @samp{hotpluggable-cpus} monitor command.
209 @samp{node-id} property specifies @var{node} to which CPU object
210 will be assigned, it's required for @var{node} to be declared
211 with @samp{node} option before it's used with @samp{cpu} option.
216 -smp 1,sockets=2,maxcpus=2 \
217 -numa node,nodeid=0 -numa node,nodeid=1 \
218 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1
221 @samp{mem} assigns a given RAM amount to a node. @samp{memdev}
222 assigns RAM from a given memory backend device to a node. If
223 @samp{mem} and @samp{memdev} are omitted in all nodes, RAM is
224 split equally between them.
226 @samp{mem} and @samp{memdev} are mutually exclusive. Furthermore,
227 if one node uses @samp{memdev}, all of them have to use it.
229 @samp{initiator} is an additional option that points to an @var{initiator}
230 NUMA node that has best performance (the lowest latency or largest bandwidth)
231 to this NUMA @var{node}. Note that this option can be set only when
232 the machine property 'hmat' is set to 'on'.
234 Following example creates a machine with 2 NUMA nodes, node 0 has CPU.
235 node 1 has only memory, and its initiator is node 0. Note that because
236 node 0 has CPU, by default the initiator of node 0 is itself and must be
240 -m 2G,slots=2,maxmem=4G \
241 -object memory-backend-ram,size=1G,id=m0 \
242 -object memory-backend-ram,size=1G,id=m1 \
243 -numa node,nodeid=0,memdev=m0 \
244 -numa node,nodeid=1,memdev=m1,initiator=0 \
245 -smp 2,sockets=2,maxcpus=2 \
246 -numa cpu,node-id=0,socket-id=0 \
247 -numa cpu,node-id=0,socket-id=1
250 @var{source} and @var{destination} are NUMA node IDs.
251 @var{distance} is the NUMA distance from @var{source} to @var{destination}.
252 The distance from a node to itself is always 10. If any pair of nodes is
253 given a distance, then all pairs must be given distances. Although, when
254 distances are only given in one direction for each pair of nodes, then
255 the distances in the opposite directions are assumed to be the same. If,
256 however, an asymmetrical pair of distances is given for even one node
257 pair, then all node pairs must be provided distance values for both
258 directions, even when they are symmetrical. When a node is unreachable
259 from another node, set the pair's distance to 255.
261 Note that the -@option{numa} option doesn't allocate any of the
262 specified resources, it just assigns existing resources to NUMA
263 nodes. This means that one still has to use the @option{-m},
264 @option{-smp} options to allocate RAM and VCPUs respectively.
268 DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
269 "-add-fd fd=fd,set=set[,opaque=opaque]\n"
270 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
272 @item -add-fd fd=@var{fd},set=@var{set}[,opaque=@var{opaque}]
275 Add a file descriptor to an fd set. Valid options are:
279 This option defines the file descriptor of which a duplicate is added to fd set.
280 The file descriptor cannot be stdin, stdout, or stderr.
282 This option defines the ID of the fd set to add the file descriptor to.
283 @item opaque=@var{opaque}
284 This option defines a free-form string that can be used to describe @var{fd}.
287 You can open an image using pre-opened file descriptors from an fd set:
289 @value{qemu_system} \
290 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
291 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
292 -drive file=/dev/fdset/2,index=0,media=disk
296 DEF("set", HAS_ARG, QEMU_OPTION_set,
297 "-set group.id.arg=value\n"
298 " set <arg> parameter for item <id> of type <group>\n"
299 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL)
301 @item -set @var{group}.@var{id}.@var{arg}=@var{value}
303 Set parameter @var{arg} for item @var{id} of type @var{group}
306 DEF("global", HAS_ARG, QEMU_OPTION_global,
307 "-global driver.property=value\n"
308 "-global driver=driver,property=property,value=value\n"
309 " set a global default for a driver property\n",
312 @item -global @var{driver}.@var{prop}=@var{value}
313 @itemx -global driver=@var{driver},property=@var{property},value=@var{value}
315 Set default value of @var{driver}'s property @var{prop} to @var{value}, e.g.:
318 @value{qemu_system_x86} -global ide-hd.physical_block_size=4096 disk-image.img
321 In particular, you can use this to set driver properties for devices which are
322 created automatically by the machine model. To create a device which is not
323 created automatically and set properties on it, use -@option{device}.
325 -global @var{driver}.@var{prop}=@var{value} is shorthand for -global
326 driver=@var{driver},property=@var{prop},value=@var{value}. The
327 longhand syntax works even when @var{driver} contains a dot.
330 DEF("boot", HAS_ARG, QEMU_OPTION_boot,
331 "-boot [order=drives][,once=drives][,menu=on|off]\n"
332 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
333 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
334 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
335 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n"
336 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
339 @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]
341 Specify boot order @var{drives} as a string of drive letters. Valid
342 drive letters depend on the target architecture. The x86 PC uses: a, b
343 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p (Etherboot
344 from network adapter 1-4), hard disk boot is the default. To apply a
345 particular boot order only on the first startup, specify it via
346 @option{once}. Note that the @option{order} or @option{once} parameter
347 should not be used together with the @option{bootindex} property of
348 devices, since the firmware implementations normally do not support both
351 Interactive boot menus/prompts can be enabled via @option{menu=on} as far
352 as firmware/BIOS supports them. The default is non-interactive boot.
354 A splash picture could be passed to bios, enabling user to show it as logo,
355 when option splash=@var{sp_name} is given and menu=on, If firmware/BIOS
356 supports them. Currently Seabios for X86 system support it.
357 limitation: The splash file could be a jpeg file or a BMP file in 24 BPP
358 format(true color). The resolution should be supported by the SVGA mode, so
359 the recommended is 320x240, 640x480, 800x640.
361 A timeout could be passed to bios, guest will pause for @var{rb_timeout} ms
362 when boot failed, then reboot. If @var{rb_timeout} is '-1', guest will not
363 reboot, qemu passes '-1' to bios by default. Currently Seabios for X86
366 Do strict boot via @option{strict=on} as far as firmware/BIOS
367 supports it. This only effects when boot priority is changed by
368 bootindex options. The default is non-strict boot.
371 # try to boot from network first, then from hard disk
372 @value{qemu_system_x86} -boot order=nc
373 # boot from CD-ROM first, switch back to default order after reboot
374 @value{qemu_system_x86} -boot once=d
375 # boot with a splash picture for 5 seconds.
376 @value{qemu_system_x86} -boot menu=on,splash=/root/boot.bmp,splash-time=5000
379 Note: The legacy format '-boot @var{drives}' is still supported but its
380 use is discouraged as it may be removed from future versions.
383 DEF("m", HAS_ARG, QEMU_OPTION_m,
384 "-m [size=]megs[,slots=n,maxmem=size]\n"
385 " configure guest RAM\n"
386 " size: initial amount of guest memory\n"
387 " slots: number of hotplug slots (default: none)\n"
388 " maxmem: maximum amount of guest memory (default: none)\n"
389 "NOTE: Some architectures might enforce a specific granularity\n",
392 @item -m [size=]@var{megs}[,slots=n,maxmem=size]
394 Sets guest startup RAM size to @var{megs} megabytes. Default is 128 MiB.
395 Optionally, a suffix of ``M'' or ``G'' can be used to signify a value in
396 megabytes or gigabytes respectively. Optional pair @var{slots}, @var{maxmem}
397 could be used to set amount of hotpluggable memory slots and maximum amount of
398 memory. Note that @var{maxmem} must be aligned to the page size.
400 For example, the following command-line sets the guest startup RAM size to
401 1GB, creates 3 slots to hotplug additional memory and sets the maximum
402 memory the guest can reach to 4GB:
405 @value{qemu_system} -m 1G,slots=3,maxmem=4G
408 If @var{slots} and @var{maxmem} are not specified, memory hotplug won't
409 be enabled and the guest startup RAM will never increase.
412 DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath,
413 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL)
415 @item -mem-path @var{path}
417 Allocate guest RAM from a temporarily created file in @var{path}.
420 DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc,
421 "-mem-prealloc preallocate guest memory (use with -mem-path)\n",
425 @findex -mem-prealloc
426 Preallocate memory when using -mem-path.
429 DEF("k", HAS_ARG, QEMU_OPTION_k,
430 "-k language use keyboard layout (for example 'fr' for French)\n",
433 @item -k @var{language}
435 Use keyboard layout @var{language} (for example @code{fr} for
436 French). This option is only needed where it is not easy to get raw PC
437 keycodes (e.g. on Macs, with some X11 servers or with a VNC or curses
438 display). You don't normally need to use it on PC/Linux or PC/Windows
441 The available layouts are:
443 ar de-ch es fo fr-ca hu ja mk no pt-br sv
444 da en-gb et fr fr-ch is lt nl pl ru th
445 de en-us fi fr-be hr it lv nl-be pt sl tr
448 The default is @code{en-us}.
452 HXCOMM Deprecated by -audiodev
453 DEF("audio-help", 0, QEMU_OPTION_audio_help,
454 "-audio-help show -audiodev equivalent of the currently specified audio settings\n",
459 Will show the -audiodev equivalent of the currently specified
460 (deprecated) environment variables.
463 DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
464 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
465 " specifies the audio backend to use\n"
466 " id= identifier of the backend\n"
467 " timer-period= timer period in microseconds\n"
468 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
469 " in|out.fixed-settings= use fixed settings for host audio\n"
470 " in|out.frequency= frequency to use with fixed settings\n"
471 " in|out.channels= number of channels to use with fixed settings\n"
472 " in|out.format= sample format to use with fixed settings\n"
473 " valid values: s8, s16, s32, u8, u16, u32\n"
474 " in|out.voices= number of voices to use\n"
475 " in|out.buffer-length= length of buffer in microseconds\n"
476 "-audiodev none,id=id,[,prop[=value][,...]]\n"
477 " dummy driver that discards all output\n"
478 #ifdef CONFIG_AUDIO_ALSA
479 "-audiodev alsa,id=id[,prop[=value][,...]]\n"
480 " in|out.dev= name of the audio device to use\n"
481 " in|out.period-length= length of period in microseconds\n"
482 " in|out.try-poll= attempt to use poll mode\n"
483 " threshold= threshold (in microseconds) when playback starts\n"
485 #ifdef CONFIG_AUDIO_COREAUDIO
486 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n"
487 " in|out.buffer-count= number of buffers\n"
489 #ifdef CONFIG_AUDIO_DSOUND
490 "-audiodev dsound,id=id[,prop[=value][,...]]\n"
491 " latency= add extra latency to playback in microseconds\n"
493 #ifdef CONFIG_AUDIO_OSS
494 "-audiodev oss,id=id[,prop[=value][,...]]\n"
495 " in|out.dev= path of the audio device to use\n"
496 " in|out.buffer-count= number of buffers\n"
497 " in|out.try-poll= attempt to use poll mode\n"
498 " try-mmap= try using memory mapped access\n"
499 " exclusive= open device in exclusive mode\n"
500 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n"
502 #ifdef CONFIG_AUDIO_PA
503 "-audiodev pa,id=id[,prop[=value][,...]]\n"
504 " server= PulseAudio server address\n"
505 " in|out.name= source/sink device name\n"
506 " in|out.latency= desired latency in microseconds\n"
508 #ifdef CONFIG_AUDIO_SDL
509 "-audiodev sdl,id=id[,prop[=value][,...]]\n"
512 "-audiodev spice,id=id[,prop[=value][,...]]\n"
514 "-audiodev wav,id=id[,prop[=value][,...]]\n"
515 " path= path of wav file to record\n",
518 @item -audiodev [driver=]@var{driver},id=@var{id}[,@var{prop}[=@var{value}][,...]]
520 Adds a new audio backend @var{driver} identified by @var{id}. There are
521 global and driver specific properties. Some values can be set
522 differently for input and output, they're marked with @code{in|out.}.
523 You can set the input's property with @code{in.@var{prop}} and the
524 output's property with @code{out.@var{prop}}. For example:
526 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
527 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
530 NOTE: parameter validation is known to be incomplete, in many cases
531 specifying an invalid option causes QEMU to print an error message and
532 continue emulation without sound.
534 Valid global options are:
537 @item id=@var{identifier}
538 Identifies the audio backend.
540 @item timer-period=@var{period}
541 Sets the timer @var{period} used by the audio subsystem in microseconds.
542 Default is 10000 (10 ms).
544 @item in|out.mixing-engine=on|off
545 Use QEMU's mixing engine to mix all streams inside QEMU and convert
546 audio formats when not supported by the backend. When off,
547 @var{fixed-settings} must be off too. Note that disabling this option
548 means that the selected backend must support multiple streams and the
549 audio formats used by the virtual cards, otherwise you'll get no sound.
550 It's not recommended to disable this option unless you want to use 5.1
551 or 7.1 audio, as mixing engine only supports mono and stereo audio.
554 @item in|out.fixed-settings=on|off
555 Use fixed settings for host audio. When off, it will change based on
556 how the guest opens the sound card. In this case you must not specify
557 @var{frequency}, @var{channels} or @var{format}. Default is on.
559 @item in|out.frequency=@var{frequency}
560 Specify the @var{frequency} to use when using @var{fixed-settings}.
563 @item in|out.channels=@var{channels}
564 Specify the number of @var{channels} to use when using
565 @var{fixed-settings}. Default is 2 (stereo).
567 @item in|out.format=@var{format}
568 Specify the sample @var{format} to use when using @var{fixed-settings}.
569 Valid values are: @code{s8}, @code{s16}, @code{s32}, @code{u8},
570 @code{u16}, @code{u32}. Default is @code{s16}.
572 @item in|out.voices=@var{voices}
573 Specify the number of @var{voices} to use. Default is 1.
575 @item in|out.buffer-length=@var{usecs}
576 Sets the size of the buffer in microseconds.
580 @item -audiodev none,id=@var{id}[,@var{prop}[=@var{value}][,...]]
581 Creates a dummy backend that discards all outputs. This backend has no
582 backend specific properties.
584 @item -audiodev alsa,id=@var{id}[,@var{prop}[=@var{value}][,...]]
585 Creates backend using the ALSA. This backend is only available on
588 ALSA specific options are:
592 @item in|out.dev=@var{device}
593 Specify the ALSA @var{device} to use for input and/or output. Default
596 @item in|out.period-length=@var{usecs}
597 Sets the period length in microseconds.
599 @item in|out.try-poll=on|off
600 Attempt to use poll mode with the device. Default is on.
602 @item threshold=@var{threshold}
603 Threshold (in microseconds) when playback starts. Default is 0.
607 @item -audiodev coreaudio,id=@var{id}[,@var{prop}[=@var{value}][,...]]
608 Creates a backend using Apple's Core Audio. This backend is only
609 available on Mac OS and only supports playback.
611 Core Audio specific options are:
615 @item in|out.buffer-count=@var{count}
616 Sets the @var{count} of the buffers.
620 @item -audiodev dsound,id=@var{id}[,@var{prop}[=@var{value}][,...]]
621 Creates a backend using Microsoft's DirectSound. This backend is only
622 available on Windows and only supports playback.
624 DirectSound specific options are:
628 @item latency=@var{usecs}
629 Add extra @var{usecs} microseconds latency to playback. Default is
634 @item -audiodev oss,id=@var{id}[,@var{prop}[=@var{value}][,...]]
635 Creates a backend using OSS. This backend is available on most
638 OSS specific options are:
642 @item in|out.dev=@var{device}
643 Specify the file name of the OSS @var{device} to use. Default is
646 @item in|out.buffer-count=@var{count}
647 Sets the @var{count} of the buffers.
649 @item in|out.try-poll=on|of
650 Attempt to use poll mode with the device. Default is on.
652 @item try-mmap=on|off
653 Try using memory mapped device access. Default is off.
655 @item exclusive=on|off
656 Open the device in exclusive mode (vmix won't work in this case).
659 @item dsp-policy=@var{policy}
660 Sets the timing policy (between 0 and 10, where smaller number means
661 smaller latency but higher CPU usage). Use -1 to use buffer sizes
662 specified by @code{buffer} and @code{buffer-count}. This option is
663 ignored if you do not have OSS 4. Default is 5.
667 @item -audiodev pa,id=@var{id}[,@var{prop}[=@var{value}][,...]]
668 Creates a backend using PulseAudio. This backend is available on most
671 PulseAudio specific options are:
675 @item server=@var{server}
676 Sets the PulseAudio @var{server} to connect to.
678 @item in|out.name=@var{sink}
679 Use the specified source/sink for recording/playback.
681 @item in|out.latency=@var{usecs}
682 Desired latency in microseconds. The PulseAudio server will try to honor this
683 value but actual latencies may be lower or higher.
687 @item -audiodev sdl,id=@var{id}[,@var{prop}[=@var{value}][,...]]
688 Creates a backend using SDL. This backend is available on most systems,
689 but you should use your platform's native backend if possible. This
690 backend has no backend specific properties.
692 @item -audiodev spice,id=@var{id}[,@var{prop}[=@var{value}][,...]]
693 Creates a backend that sends audio through SPICE. This backend requires
694 @code{-spice} and automatically selected in that case, so usually you
695 can ignore this option. This backend has no backend specific
698 @item -audiodev wav,id=@var{id}[,@var{prop}[=@var{value}][,...]]
699 Creates a backend that writes audio to a WAV file.
701 Backend specific options are:
705 @item path=@var{path}
706 Write recorded audio into the specified file. Default is
712 DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
713 "-soundhw c1,... enable audio support\n"
714 " and only specified sound cards (comma separated list)\n"
715 " use '-soundhw help' to get the list of supported cards\n"
716 " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
718 @item -soundhw @var{card1}[,@var{card2},...] or -soundhw all
720 Enable audio and selected sound hardware. Use 'help' to print all
721 available sound hardware. For example:
724 @value{qemu_system_x86} -soundhw sb16,adlib disk.img
725 @value{qemu_system_x86} -soundhw es1370 disk.img
726 @value{qemu_system_x86} -soundhw ac97 disk.img
727 @value{qemu_system_x86} -soundhw hda disk.img
728 @value{qemu_system_x86} -soundhw all disk.img
729 @value{qemu_system_x86} -soundhw help
732 Note that Linux's i810_audio OSS kernel (for AC97) module might
733 require manually specifying clocking.
736 modprobe i810_audio clocking=48000
740 DEF("device", HAS_ARG, QEMU_OPTION_device,
741 "-device driver[,prop[=value][,...]]\n"
742 " add device (based on driver)\n"
743 " prop=value,... sets driver properties\n"
744 " use '-device help' to print all possible drivers\n"
745 " use '-device driver,help' to print all possible properties\n",
748 @item -device @var{driver}[,@var{prop}[=@var{value}][,...]]
750 Add device @var{driver}. @var{prop}=@var{value} sets driver
751 properties. Valid properties depend on the driver. To get help on
752 possible drivers and properties, use @code{-device help} and
753 @code{-device @var{driver},help}.
756 @item -device ipmi-bmc-sim,id=@var{id}[,slave_addr=@var{val}][,sdrfile=@var{file}][,furareasize=@var{val}][,furdatafile=@var{file}][,guid=@var{uuid}]
758 Add an IPMI BMC. This is a simulation of a hardware management
759 interface processor that normally sits on a system. It provides
760 a watchdog and the ability to reset and power control the system.
761 You need to connect this to an IPMI interface to make it useful
763 The IPMI slave address to use for the BMC. The default is 0x20.
764 This address is the BMC's address on the I2C network of management
765 controllers. If you don't know what this means, it is safe to ignore
770 The BMC id for interfaces to use this device.
771 @item slave_addr=@var{val}
772 Define slave address to use for the BMC. The default is 0x20.
773 @item sdrfile=@var{file}
774 file containing raw Sensor Data Records (SDR) data. The default is none.
775 @item fruareasize=@var{val}
776 size of a Field Replaceable Unit (FRU) area. The default is 1024.
777 @item frudatafile=@var{file}
778 file containing raw Field Replaceable Unit (FRU) inventory data. The default is none.
779 @item guid=@var{uuid}
780 value for the GUID for the BMC, in standard UUID format. If this is set,
781 get "Get GUID" command to the BMC will return it. Otherwise "Get GUID"
782 will return an error.
785 @item -device ipmi-bmc-extern,id=@var{id},chardev=@var{id}[,slave_addr=@var{val}]
787 Add a connection to an external IPMI BMC simulator. Instead of
788 locally emulating the BMC like the above item, instead connect
789 to an external entity that provides the IPMI services.
791 A connection is made to an external BMC simulator. If you do this, it
792 is strongly recommended that you use the "reconnect=" chardev option
793 to reconnect to the simulator if the connection is lost. Note that if
794 this is not used carefully, it can be a security issue, as the
795 interface has the ability to send resets, NMIs, and power off the VM.
796 It's best if QEMU makes a connection to an external simulator running
797 on a secure port on localhost, so neither the simulator nor QEMU is
798 exposed to any outside network.
800 See the "lanserv/README.vm" file in the OpenIPMI library for more
801 details on the external interface.
803 @item -device isa-ipmi-kcs,bmc=@var{id}[,ioport=@var{val}][,irq=@var{val}]
805 Add a KCS IPMI interafce on the ISA bus. This also adds a
806 corresponding ACPI and SMBIOS entries, if appropriate.
810 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
811 @item ioport=@var{val}
812 Define the I/O address of the interface. The default is 0xca0 for KCS.
814 Define the interrupt to use. The default is 5. To disable interrupts,
818 @item -device isa-ipmi-bt,bmc=@var{id}[,ioport=@var{val}][,irq=@var{val}]
820 Like the KCS interface, but defines a BT interface. The default port is
821 0xe4 and the default interrupt is 5.
825 DEF("name", HAS_ARG, QEMU_OPTION_name,
826 "-name string1[,process=string2][,debug-threads=on|off]\n"
827 " set the name of the guest\n"
828 " string1 sets the window title and string2 the process name\n"
829 " When debug-threads is enabled, individual threads are given a separate name\n"
830 " NOTE: The thread names are for debugging and not a stable API.\n",
833 @item -name @var{name}
835 Sets the @var{name} of the guest.
836 This name will be displayed in the SDL window caption.
837 The @var{name} will also be used for the VNC server.
838 Also optionally set the top visible process name in Linux.
839 Naming of individual threads can also be enabled on Linux to aid debugging.
842 DEF("uuid", HAS_ARG, QEMU_OPTION_uuid,
843 "-uuid %08x-%04x-%04x-%04x-%012x\n"
844 " specify machine UUID\n", QEMU_ARCH_ALL)
846 @item -uuid @var{uuid}
856 DEFHEADING(Block device options:)
861 DEF("fda", HAS_ARG, QEMU_OPTION_fda,
862 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
863 DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
865 @item -fda @var{file}
866 @itemx -fdb @var{file}
869 Use @var{file} as floppy disk 0/1 image (@pxref{disk_images}).
872 DEF("hda", HAS_ARG, QEMU_OPTION_hda,
873 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL)
874 DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
875 DEF("hdc", HAS_ARG, QEMU_OPTION_hdc,
876 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL)
877 DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
879 @item -hda @var{file}
880 @itemx -hdb @var{file}
881 @itemx -hdc @var{file}
882 @itemx -hdd @var{file}
887 Use @var{file} as hard disk 0, 1, 2 or 3 image (@pxref{disk_images}).
890 DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom,
891 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n",
894 @item -cdrom @var{file}
896 Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and
897 @option{-cdrom} at the same time). You can use the host CD-ROM by
898 using @file{/dev/cdrom} as filename (@pxref{host_drives}).
901 DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev,
902 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n"
903 " [,cache.direct=on|off][,cache.no-flush=on|off]\n"
904 " [,read-only=on|off][,auto-read-only=on|off]\n"
905 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n"
906 " [,driver specific parameters...]\n"
907 " configure a block backend\n", QEMU_ARCH_ALL)
909 @item -blockdev @var{option}[,@var{option}[,@var{option}[,...]]]
912 Define a new block driver node. Some of the options apply to all block drivers,
913 other options are only accepted for a specific block driver. See below for a
914 list of generic options and options for the most common block drivers.
916 Options that expect a reference to another node (e.g. @code{file}) can be
917 given in two ways. Either you specify the node name of an already existing node
918 (file=@var{node-name}), or you define a new node inline, adding options
919 for the referenced node after a dot (file.filename=@var{path},file.aio=native).
921 A block driver node created with @option{-blockdev} can be used for a guest
922 device by specifying its node name for the @code{drive} property in a
923 @option{-device} argument that defines a block device.
926 @item Valid options for any block driver node:
930 Specifies the block driver to use for the given node.
932 This defines the name of the block driver node by which it will be referenced
933 later. The name must be unique, i.e. it must not match the name of a different
934 block driver node, or (if you use @option{-drive} as well) the ID of a drive.
936 If no node name is specified, it is automatically generated. The generated node
937 name is not intended to be predictable and changes between QEMU invocations.
938 For the top level, an explicit node name must be specified.
940 Open the node read-only. Guest write attempts will fail.
942 Note that some block drivers support only read-only access, either generally or
943 in certain configurations. In this case, the default value
944 @option{read-only=off} does not work and the option must be specified
947 If @option{auto-read-only=on} is set, QEMU may fall back to read-only usage
948 even when @option{read-only=off} is requested, or even switch between modes as
949 needed, e.g. depending on whether the image file is writable or whether a
950 writing user is attached to the node.
952 Override the image locking system of QEMU by forcing the node to utilize
953 weaker shared access for permissions where it would normally request exclusive
954 access. When there is the potential for multiple instances to have the same
955 file open (whether this invocation of QEMU is the first or the second
956 instance), both instances must permit shared access for the second instance to
957 succeed at opening the file.
959 Enabling @option{force-share=on} requires @option{read-only=on}.
961 The host page cache can be avoided with @option{cache.direct=on}. This will
962 attempt to do disk IO directly to the guest's memory. QEMU may still perform an
963 internal copy of the data.
965 In case you don't care about data integrity over host failures, you can use
966 @option{cache.no-flush=on}. This option tells QEMU that it never needs to write
967 any data to the disk but can instead keep things in cache. If anything goes
968 wrong, like your host losing power, the disk storage getting disconnected
969 accidentally, etc. your image will most probably be rendered unusable.
970 @item discard=@var{discard}
971 @var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and controls
972 whether @code{discard} (also known as @code{trim} or @code{unmap}) requests are
973 ignored or passed to the filesystem. Some machine types may not support
975 @item detect-zeroes=@var{detect-zeroes}
976 @var{detect-zeroes} is "off", "on" or "unmap" and enables the automatic
977 conversion of plain zero writes by the OS to driver specific optimized
978 zero write commands. You may even choose "unmap" if @var{discard} is set
979 to "unmap" to allow a zero write to be converted to an @code{unmap} operation.
982 @item Driver-specific options for @code{file}
984 This is the protocol-level block driver for accessing regular files.
988 The path to the image file in the local filesystem
990 Specifies the AIO backend (threads/native, default: threads)
992 Specifies whether the image file is protected with Linux OFD / POSIX locks. The
993 default is to use the Linux Open File Descriptor API if available, otherwise no
994 lock is applied. (auto/on/off, default: auto)
998 -blockdev driver=file,node-name=disk,filename=disk.img
1001 @item Driver-specific options for @code{raw}
1003 This is the image format block driver for raw images. It is usually
1004 stacked on top of a protocol level block driver such as @code{file}.
1008 Reference to or definition of the data source block driver node
1009 (e.g. a @code{file} driver node)
1013 -blockdev driver=file,node-name=disk_file,filename=disk.img
1014 -blockdev driver=raw,node-name=disk,file=disk_file
1018 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1021 @item Driver-specific options for @code{qcow2}
1023 This is the image format block driver for qcow2 images. It is usually
1024 stacked on top of a protocol level block driver such as @code{file}.
1028 Reference to or definition of the data source block driver node
1029 (e.g. a @code{file} driver node)
1032 Reference to or definition of the backing file block device (default is taken
1033 from the image file). It is allowed to pass @code{null} here in order to disable
1034 the default backing file.
1036 @item lazy-refcounts
1037 Whether to enable the lazy refcounts feature (on/off; default is taken from the
1041 The maximum total size of the L2 table and refcount block caches in bytes
1042 (default: the sum of l2-cache-size and refcount-cache-size)
1045 The maximum size of the L2 table cache in bytes
1046 (default: if cache-size is not specified - 32M on Linux platforms, and 8M on
1047 non-Linux platforms; otherwise, as large as possible within the cache-size,
1048 while permitting the requested or the minimal refcount cache size)
1050 @item refcount-cache-size
1051 The maximum size of the refcount block cache in bytes
1052 (default: 4 times the cluster size; or if cache-size is specified, the part of
1053 it which is not used for the L2 cache)
1055 @item cache-clean-interval
1056 Clean unused entries in the L2 and refcount caches. The interval is in seconds.
1057 The default value is 600 on supporting platforms, and 0 on other platforms.
1058 Setting it to 0 disables this feature.
1060 @item pass-discard-request
1061 Whether discard requests to the qcow2 device should be forwarded to the data
1062 source (on/off; default: on if discard=unmap is specified, off otherwise)
1064 @item pass-discard-snapshot
1065 Whether discard requests for the data source should be issued when a snapshot
1066 operation (e.g. deleting a snapshot) frees clusters in the qcow2 file (on/off;
1069 @item pass-discard-other
1070 Whether discard requests for the data source should be issued on other
1071 occasions where a cluster gets freed (on/off; default: off)
1074 Which overlap checks to perform for writes to the image
1075 (none/constant/cached/all; default: cached). For details or finer
1076 granularity control refer to the QAPI documentation of @code{blockdev-add}.
1081 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1082 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1086 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1089 @item Driver-specific options for other drivers
1090 Please refer to the QAPI documentation of the @code{blockdev-add} QMP command.
1096 DEF("drive", HAS_ARG, QEMU_OPTION_drive,
1097 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
1098 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
1099 " [,snapshot=on|off][,rerror=ignore|stop|report]\n"
1100 " [,werror=ignore|stop|report|enospc][,id=name][,aio=threads|native]\n"
1101 " [,readonly=on|off][,copy-on-read=on|off]\n"
1102 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
1103 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
1104 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n"
1105 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n"
1106 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n"
1107 " [[,iops_size=is]]\n"
1109 " use 'file' as a drive image\n", QEMU_ARCH_ALL)
1111 @item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
1114 Define a new drive. This includes creating a block driver node (the backend) as
1115 well as a guest device, and is mostly a shortcut for defining the corresponding
1116 @option{-blockdev} and @option{-device} options.
1118 @option{-drive} accepts all options that are accepted by @option{-blockdev}. In
1119 addition, it knows the following options:
1122 @item file=@var{file}
1123 This option defines which disk image (@pxref{disk_images}) to use with
1124 this drive. If the filename contains comma, you must double it
1125 (for instance, "file=my,,file" to use file "my,file").
1127 Special files such as iSCSI devices can be specified using protocol
1128 specific URLs. See the section for "Device URL Syntax" for more information.
1129 @item if=@var{interface}
1130 This option defines on which type on interface the drive is connected.
1131 Available types are: ide, scsi, sd, mtd, floppy, pflash, virtio, none.
1132 @item bus=@var{bus},unit=@var{unit}
1133 These options define where is connected the drive by defining the bus number and
1135 @item index=@var{index}
1136 This option defines where is connected the drive by using an index in the list
1137 of available connectors of a given interface type.
1138 @item media=@var{media}
1139 This option defines the type of the media: disk or cdrom.
1140 @item snapshot=@var{snapshot}
1141 @var{snapshot} is "on" or "off" and controls snapshot mode for the given drive
1142 (see @option{-snapshot}).
1143 @item cache=@var{cache}
1144 @var{cache} is "none", "writeback", "unsafe", "directsync" or "writethrough"
1145 and controls how the host cache is used to access block data. This is a
1146 shortcut that sets the @option{cache.direct} and @option{cache.no-flush}
1147 options (as in @option{-blockdev}), and additionally @option{cache.writeback},
1148 which provides a default for the @option{write-cache} option of block guest
1149 devices (as in @option{-device}). The modes correspond to the following
1152 @c Our texi2pod.pl script doesn't support @multitable, so fall back to using
1153 @c plain ASCII art (well, UTF-8 art really). This looks okay both in the manpage
1154 @c and the HTML output.
1156 @ │ cache.writeback cache.direct cache.no-flush
1157 ─────────────┼─────────────────────────────────────────────────
1158 writeback │ on off off
1160 writethrough │ off off off
1161 directsync │ off on off
1162 unsafe │ on off on
1165 The default mode is @option{cache=writeback}.
1168 @var{aio} is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO.
1169 @item format=@var{format}
1170 Specify which disk @var{format} will be used rather than detecting
1171 the format. Can be used to specify format=raw to avoid interpreting
1172 an untrusted format header.
1173 @item werror=@var{action},rerror=@var{action}
1174 Specify which @var{action} to take on write and read errors. Valid actions are:
1175 "ignore" (ignore the error and try to continue), "stop" (pause QEMU),
1176 "report" (report the error to the guest), "enospc" (pause QEMU only if the
1177 host disk is full; report the error to the guest otherwise).
1178 The default setting is @option{werror=enospc} and @option{rerror=report}.
1179 @item copy-on-read=@var{copy-on-read}
1180 @var{copy-on-read} is "on" or "off" and enables whether to copy read backing
1181 file sectors into the image file.
1182 @item bps=@var{b},bps_rd=@var{r},bps_wr=@var{w}
1183 Specify bandwidth throttling limits in bytes per second, either for all request
1184 types or for reads or writes only. Small values can lead to timeouts or hangs
1185 inside the guest. A safe minimum for disks is 2 MB/s.
1186 @item bps_max=@var{bm},bps_rd_max=@var{rm},bps_wr_max=@var{wm}
1187 Specify bursts in bytes per second, either for all request types or for reads
1188 or writes only. Bursts allow the guest I/O to spike above the limit
1190 @item iops=@var{i},iops_rd=@var{r},iops_wr=@var{w}
1191 Specify request rate limits in requests per second, either for all request
1192 types or for reads or writes only.
1193 @item iops_max=@var{bm},iops_rd_max=@var{rm},iops_wr_max=@var{wm}
1194 Specify bursts in requests per second, either for all request types or for reads
1195 or writes only. Bursts allow the guest I/O to spike above the limit
1197 @item iops_size=@var{is}
1198 Let every @var{is} bytes of a request count as a new request for iops
1199 throttling purposes. Use this option to prevent guests from circumventing iops
1200 limits by sending fewer but larger requests.
1202 Join a throttling quota group with given name @var{g}. All drives that are
1203 members of the same group are accounted for together. Use this option to
1204 prevent guests from circumventing throttling limits by using many small disks
1205 instead of a single larger disk.
1208 By default, the @option{cache.writeback=on} mode is used. It will report data
1209 writes as completed as soon as the data is present in the host page cache.
1210 This is safe as long as your guest OS makes sure to correctly flush disk caches
1211 where needed. If your guest OS does not handle volatile disk write caches
1212 correctly and your host crashes or loses power, then the guest may experience
1215 For such guests, you should consider using @option{cache.writeback=off}. This
1216 means that the host page cache will be used to read and write data, but write
1217 notification will be sent to the guest only after QEMU has made sure to flush
1218 each write to the disk. Be aware that this has a major impact on performance.
1220 When using the @option{-snapshot} option, unsafe caching is always used.
1222 Copy-on-read avoids accessing the same backing file sectors repeatedly and is
1223 useful when the backing file is over a slow network. By default copy-on-read
1226 Instead of @option{-cdrom} you can use:
1228 @value{qemu_system} -drive file=file,index=2,media=cdrom
1231 Instead of @option{-hda}, @option{-hdb}, @option{-hdc}, @option{-hdd}, you can
1234 @value{qemu_system} -drive file=file,index=0,media=disk
1235 @value{qemu_system} -drive file=file,index=1,media=disk
1236 @value{qemu_system} -drive file=file,index=2,media=disk
1237 @value{qemu_system} -drive file=file,index=3,media=disk
1240 You can open an image using pre-opened file descriptors from an fd set:
1242 @value{qemu_system} \
1243 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \
1244 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \
1245 -drive file=/dev/fdset/2,index=0,media=disk
1248 You can connect a CDROM to the slave of ide0:
1250 @value{qemu_system_x86} -drive file=file,if=ide,index=1,media=cdrom
1253 If you don't specify the "file=" argument, you define an empty drive:
1255 @value{qemu_system_x86} -drive if=ide,index=1,media=cdrom
1258 Instead of @option{-fda}, @option{-fdb}, you can use:
1260 @value{qemu_system_x86} -drive file=file,index=0,if=floppy
1261 @value{qemu_system_x86} -drive file=file,index=1,if=floppy
1264 By default, @var{interface} is "ide" and @var{index} is automatically
1267 @value{qemu_system_x86} -drive file=a -drive file=b"
1269 is interpreted like:
1271 @value{qemu_system_x86} -hda a -hdb b
1275 DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock,
1276 "-mtdblock file use 'file' as on-board Flash memory image\n",
1279 @item -mtdblock @var{file}
1281 Use @var{file} as on-board Flash memory image.
1284 DEF("sd", HAS_ARG, QEMU_OPTION_sd,
1285 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL)
1287 @item -sd @var{file}
1289 Use @var{file} as SecureDigital card image.
1292 DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
1293 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
1295 @item -pflash @var{file}
1297 Use @var{file} as a parallel flash image.
1300 DEF("snapshot", 0, QEMU_OPTION_snapshot,
1301 "-snapshot write to temporary files instead of disk image files\n",
1306 Write to temporary files instead of disk image files. In this case,
1307 the raw disk image you use is not written back. You can however force
1308 the write back by pressing @key{C-a s} (@pxref{disk_images}).
1311 DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
1312 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1313 " [,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode]\n"
1314 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1315 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1316 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1317 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1318 " [[,throttling.iops-size=is]]\n"
1319 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly]\n"
1320 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly]\n"
1321 "-fsdev synth,id=id\n",
1326 @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}[,...]]]
1327 @itemx -fsdev proxy,id=@var{id},socket=@var{socket}[,writeout=@var{writeout}][,readonly]
1328 @itemx -fsdev proxy,id=@var{id},sock_fd=@var{sock_fd}[,writeout=@var{writeout}][,readonly]
1329 @itemx -fsdev synth,id=@var{id}[,readonly]
1331 Define a new file system device. Valid options are:
1334 Accesses to the filesystem are done by QEMU.
1336 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1338 Synthetic filesystem, only used by QTests.
1340 Specifies identifier for this device.
1341 @item path=@var{path}
1342 Specifies the export path for the file system device. Files under
1343 this path will be available to the 9p client on the guest.
1344 @item security_model=@var{security_model}
1345 Specifies the security model to be used for this export path.
1346 Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none".
1347 In "passthrough" security model, files are stored using the same
1348 credentials as they are created on the guest. This requires QEMU
1349 to run as root. In "mapped-xattr" security model, some of the file
1350 attributes like uid, gid, mode bits and link target are stored as
1351 file attributes. For "mapped-file" these attributes are stored in the
1352 hidden .virtfs_metadata directory. Directories exported by this security model cannot
1353 interact with other unix tools. "none" security model is same as
1354 passthrough except the sever won't report failures if it fails to
1355 set file attributes like ownership. Security model is mandatory
1356 only for local fsdriver. Other fsdrivers (like proxy) don't take
1357 security model as a parameter.
1358 @item writeout=@var{writeout}
1359 This is an optional argument. The only supported value is "immediate".
1360 This means that host page cache will be used to read and write data but
1361 write notification will be sent to the guest only when the data has been
1362 reported as written by the storage subsystem.
1364 Enables exporting 9p share as a readonly mount for guests. By default
1365 read-write access is given.
1366 @item socket=@var{socket}
1367 Enables proxy filesystem driver to use passed socket file for communicating
1368 with virtfs-proxy-helper(1).
1369 @item sock_fd=@var{sock_fd}
1370 Enables proxy filesystem driver to use passed socket descriptor for
1371 communicating with virtfs-proxy-helper(1). Usually a helper like libvirt
1372 will create socketpair and pass one of the fds as sock_fd.
1373 @item fmode=@var{fmode}
1374 Specifies the default mode for newly created files on the host. Works only
1375 with security models "mapped-xattr" and "mapped-file".
1376 @item dmode=@var{dmode}
1377 Specifies the default mode for newly created directories on the host. Works
1378 only with security models "mapped-xattr" and "mapped-file".
1379 @item throttling.bps-total=@var{b},throttling.bps-read=@var{r},throttling.bps-write=@var{w}
1380 Specify bandwidth throttling limits in bytes per second, either for all request
1381 types or for reads or writes only.
1382 @item throttling.bps-total-max=@var{bm},bps-read-max=@var{rm},bps-write-max=@var{wm}
1383 Specify bursts in bytes per second, either for all request types or for reads
1384 or writes only. Bursts allow the guest I/O to spike above the limit
1386 @item throttling.iops-total=@var{i},throttling.iops-read=@var{r}, throttling.iops-write=@var{w}
1387 Specify request rate limits in requests per second, either for all request
1388 types or for reads or writes only.
1389 @item throttling.iops-total-max=@var{im},throttling.iops-read-max=@var{irm}, throttling.iops-write-max=@var{iwm}
1390 Specify bursts in requests per second, either for all request types or for reads
1391 or writes only. Bursts allow the guest I/O to spike above the limit temporarily.
1392 @item throttling.iops-size=@var{is}
1393 Let every @var{is} bytes of a request count as a new request for iops
1394 throttling purposes.
1397 -fsdev option is used along with -device driver "virtio-9p-...".
1398 @item -device virtio-9p-@var{type},fsdev=@var{id},mount_tag=@var{mount_tag}
1399 Options for virtio-9p-... driver are:
1402 Specifies the variant to be used. Supported values are "pci", "ccw" or "device",
1403 depending on the machine type.
1404 @item fsdev=@var{id}
1405 Specifies the id value specified along with -fsdev option.
1406 @item mount_tag=@var{mount_tag}
1407 Specifies the tag name to be used by the guest to mount this export point.
1412 DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
1413 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1414 " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1415 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly]\n"
1416 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly]\n"
1417 "-virtfs synth,mount_tag=tag[,id=id][,readonly]\n",
1422 @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}]
1423 @itemx -virtfs proxy,socket=@var{socket},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly]
1424 @itemx -virtfs proxy,sock_fd=@var{sock_fd},mount_tag=@var{mount_tag} [,writeout=@var{writeout}][,readonly]
1425 @itemx -virtfs synth,mount_tag=@var{mount_tag}
1428 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:
1431 Accesses to the filesystem are done by QEMU.
1433 Accesses to the filesystem are done by virtfs-proxy-helper(1).
1435 Synthetic filesystem, only used by QTests.
1437 Specifies identifier for the filesystem device
1438 @item path=@var{path}
1439 Specifies the export path for the file system device. Files under
1440 this path will be available to the 9p client on the guest.
1441 @item security_model=@var{security_model}
1442 Specifies the security model to be used for this export path.
1443 Supported security models are "passthrough", "mapped-xattr", "mapped-file" and "none".
1444 In "passthrough" security model, files are stored using the same
1445 credentials as they are created on the guest. This requires QEMU
1446 to run as root. In "mapped-xattr" security model, some of the file
1447 attributes like uid, gid, mode bits and link target are stored as
1448 file attributes. For "mapped-file" these attributes are stored in the
1449 hidden .virtfs_metadata directory. Directories exported by this security model cannot
1450 interact with other unix tools. "none" security model is same as
1451 passthrough except the sever won't report failures if it fails to
1452 set file attributes like ownership. Security model is mandatory only
1453 for local fsdriver. Other fsdrivers (like proxy) don't take security
1454 model as a parameter.
1455 @item writeout=@var{writeout}
1456 This is an optional argument. The only supported value is "immediate".
1457 This means that host page cache will be used to read and write data but
1458 write notification will be sent to the guest only when the data has been
1459 reported as written by the storage subsystem.
1461 Enables exporting 9p share as a readonly mount for guests. By default
1462 read-write access is given.
1463 @item socket=@var{socket}
1464 Enables proxy filesystem driver to use passed socket file for
1465 communicating with virtfs-proxy-helper(1). Usually a helper like libvirt
1466 will create socketpair and pass one of the fds as sock_fd.
1468 Enables proxy filesystem driver to use passed 'sock_fd' as the socket
1469 descriptor for interfacing with virtfs-proxy-helper(1).
1470 @item fmode=@var{fmode}
1471 Specifies the default mode for newly created files on the host. Works only
1472 with security models "mapped-xattr" and "mapped-file".
1473 @item dmode=@var{dmode}
1474 Specifies the default mode for newly created directories on the host. Works
1475 only with security models "mapped-xattr" and "mapped-file".
1476 @item mount_tag=@var{mount_tag}
1477 Specifies the tag name to be used by the guest to mount this export point.
1478 @item multidevs=@var{multidevs}
1479 Specifies how to deal with multiple devices being shared with a 9p export.
1480 Supported behaviours are either "remap", "forbid" or "warn". The latter is
1481 the default behaviour on which virtfs 9p expects only one device to be
1482 shared with the same export, and if more than one device is shared and
1483 accessed via the same 9p export then only a warning message is logged
1484 (once) by qemu on host side. In order to avoid file ID collisions on guest
1485 you should either create a separate virtfs export for each device to be
1486 shared with guests (recommended way) or you might use "remap" instead which
1487 allows you to share multiple devices with only one export instead, which is
1488 achieved by remapping the original inode numbers from host to guest in a
1489 way that would prevent such collisions. Remapping inodes in such use cases
1490 is required because the original device IDs from host are never passed and
1491 exposed on guest. Instead all files of an export shared with virtfs always
1492 share the same device id on guest. So two files with identical inode
1493 numbers but from actually different devices on host would otherwise cause a
1494 file ID collision and hence potential misbehaviours on guest. "forbid" on
1495 the other hand assumes like "warn" that only one device is shared by the
1496 same export, however it will not only log a warning message but also
1497 deny access to additional devices on guest. Note though that "forbid" does
1498 currently not block all possible file access operations (e.g. readdir()
1499 would still return entries from other devices).
1503 DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
1504 "-iscsi [user=user][,password=password]\n"
1505 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
1506 " [,initiator-name=initiator-iqn][,id=target-iqn]\n"
1507 " [,timeout=timeout]\n"
1508 " iSCSI session parameters\n", QEMU_ARCH_ALL)
1513 Configure iSCSI session parameters.
1521 DEFHEADING(USB options:)
1526 DEF("usb", 0, QEMU_OPTION_usb,
1527 "-usb enable on-board USB host controller (if not enabled by default)\n",
1532 Enable USB emulation on machine types with an on-board USB host controller (if
1533 not enabled by default). Note that on-board USB host controllers may not
1534 support USB 3.0. In this case @option{-device qemu-xhci} can be used instead
1535 on machines with PCI.
1538 DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice,
1539 "-usbdevice name add the host or guest USB device 'name'\n",
1543 @item -usbdevice @var{devname}
1545 Add the USB device @var{devname}. Note that this option is deprecated,
1546 please use @code{-device usb-...} instead. @xref{usb_devices}.
1551 Virtual Mouse. This will override the PS/2 mouse emulation when activated.
1554 Pointer device that uses absolute coordinates (like a touchscreen). This
1555 means QEMU is able to report the mouse position without having to grab the
1556 mouse. Also overrides the PS/2 mouse emulation when activated.
1559 Braille device. This will use BrlAPI to display the braille output on a real
1570 DEFHEADING(Display options:)
1575 DEF("display", HAS_ARG, QEMU_OPTION_display,
1576 #if defined(CONFIG_SPICE)
1577 "-display spice-app[,gl=on|off]\n"
1579 #if defined(CONFIG_SDL)
1580 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off]\n"
1581 " [,window_close=on|off][,gl=on|core|es|off]\n"
1583 #if defined(CONFIG_GTK)
1584 "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
1586 #if defined(CONFIG_VNC)
1587 "-display vnc=<display>[,<optargs>]\n"
1589 #if defined(CONFIG_CURSES)
1590 "-display curses[,charset=<encoding>]\n"
1592 #if defined(CONFIG_OPENGL)
1593 "-display egl-headless[,rendernode=<file>]\n"
1596 " select display backend type\n"
1597 " The default display is equivalent to\n "
1598 #if defined(CONFIG_GTK)
1599 "\"-display gtk\"\n"
1600 #elif defined(CONFIG_SDL)
1601 "\"-display sdl\"\n"
1602 #elif defined(CONFIG_COCOA)
1603 "\"-display cocoa\"\n"
1604 #elif defined(CONFIG_VNC)
1605 "\"-vnc localhost:0,to=99,id=default\"\n"
1607 "\"-display none\"\n"
1611 @item -display @var{type}
1613 Select type of display to use. This option is a replacement for the
1614 old style -sdl/-curses/... options. Valid values for @var{type} are
1617 Display video output via SDL (usually in a separate graphics
1618 window; see the SDL documentation for other possibilities).
1620 Display video output via curses. For graphics device models which
1621 support a text mode, QEMU can display this output using a
1622 curses/ncurses interface. Nothing is displayed when the graphics
1623 device is in graphical mode or if the graphics device does not support
1624 a text mode. Generally only the VGA device models support text mode.
1625 The font charset used by the guest can be specified with the
1626 @code{charset} option, for example @code{charset=CP850} for IBM CP850
1627 encoding. The default is @code{CP437}.
1629 Do not display video output. The guest will still see an emulated
1630 graphics card, but its output will not be displayed to the QEMU
1631 user. This option differs from the -nographic option in that it
1632 only affects what is done with video output; -nographic also changes
1633 the destination of the serial and parallel port data.
1635 Display video output in a GTK window. This interface provides drop-down
1636 menus and other UI elements to configure and control the VM during
1639 Start a VNC server on display <arg>
1641 Offload all OpenGL operations to a local DRI device. For any graphical display,
1642 this display needs to be paired with either VNC or SPICE displays.
1644 Start QEMU as a Spice server and launch the default Spice client
1645 application. The Spice server will redirect the serial consoles and
1646 QEMU monitors. (Since 4.0)
1650 DEF("nographic", 0, QEMU_OPTION_nographic,
1651 "-nographic disable graphical output and redirect serial I/Os to console\n",
1656 Normally, if QEMU is compiled with graphical window support, it displays
1657 output such as guest graphics, guest console, and the QEMU monitor in a
1658 window. With this option, you can totally disable graphical output so
1659 that QEMU is a simple command line application. The emulated serial port
1660 is redirected on the console and muxed with the monitor (unless
1661 redirected elsewhere explicitly). Therefore, you can still use QEMU to
1662 debug a Linux kernel with a serial console. Use @key{C-a h} for help on
1663 switching between the console and monitor.
1666 DEF("curses", 0, QEMU_OPTION_curses,
1667 "-curses shorthand for -display curses\n",
1672 Normally, if QEMU is compiled with graphical window support, it displays
1673 output such as guest graphics, guest console, and the QEMU monitor in a
1674 window. With this option, QEMU can display the VGA output when in text
1675 mode using a curses/ncurses interface. Nothing is displayed in graphical
1679 DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
1680 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
1685 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that this also
1686 affects the special keys (for fullscreen, monitor-mode switching, etc).
1689 DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
1690 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
1695 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this also
1696 affects the special keys (for fullscreen, monitor-mode switching, etc).
1699 DEF("no-quit", 0, QEMU_OPTION_no_quit,
1700 "-no-quit disable SDL window close capability\n", QEMU_ARCH_ALL)
1704 Disable SDL window close capability.
1707 DEF("sdl", 0, QEMU_OPTION_sdl,
1708 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL)
1715 DEF("spice", HAS_ARG, QEMU_OPTION_spice,
1716 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
1717 " [,x509-key-file=<file>][,x509-key-password=<file>]\n"
1718 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
1719 " [,x509-dh-key-file=<file>][,addr=addr][,ipv4|ipv6|unix]\n"
1720 " [,tls-ciphers=<list>]\n"
1721 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
1722 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
1723 " [,sasl][,password=<secret>][,disable-ticketing]\n"
1724 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
1725 " [,jpeg-wan-compression=[auto|never|always]]\n"
1726 " [,zlib-glz-wan-compression=[auto|never|always]]\n"
1727 " [,streaming-video=[off|all|filter]][,disable-copy-paste]\n"
1728 " [,disable-agent-file-xfer][,agent-mouse=[on|off]]\n"
1729 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
1730 " [,gl=[on|off]][,rendernode=<file>]\n"
1732 " at least one of {port, tls-port} is mandatory\n",
1735 @item -spice @var{option}[,@var{option}[,...]]
1737 Enable the spice remote desktop protocol. Valid options are
1742 Set the TCP port spice is listening on for plaintext channels.
1745 Set the IP address spice is listening on. Default is any address.
1750 Force using the specified IP version.
1752 @item password=<secret>
1753 Set the password you need to authenticate.
1756 Require that the client use SASL to authenticate with the spice.
1757 The exact choice of authentication method used is controlled from the
1758 system / user's SASL configuration file for the 'qemu' service. This
1759 is typically found in /etc/sasl2/qemu.conf. If running QEMU as an
1760 unprivileged user, an environment variable SASL_CONF_PATH can be used
1761 to make it search alternate locations for the service config.
1762 While some SASL auth methods can also provide data encryption (eg GSSAPI),
1763 it is recommended that SASL always be combined with the 'tls' and
1764 'x509' settings to enable use of SSL and server certificates. This
1765 ensures a data encryption preventing compromise of authentication
1768 @item disable-ticketing
1769 Allow client connects without authentication.
1771 @item disable-copy-paste
1772 Disable copy paste between the client and the guest.
1774 @item disable-agent-file-xfer
1775 Disable spice-vdagent based file-xfer between the client and the guest.
1778 Set the TCP port spice is listening on for encrypted channels.
1780 @item x509-dir=<dir>
1781 Set the x509 file directory. Expects same filenames as -vnc $display,x509=$dir
1783 @item x509-key-file=<file>
1784 @itemx x509-key-password=<file>
1785 @itemx x509-cert-file=<file>
1786 @itemx x509-cacert-file=<file>
1787 @itemx x509-dh-key-file=<file>
1788 The x509 file names can also be configured individually.
1790 @item tls-ciphers=<list>
1791 Specify which ciphers to use.
1793 @item tls-channel=[main|display|cursor|inputs|record|playback]
1794 @itemx plaintext-channel=[main|display|cursor|inputs|record|playback]
1795 Force specific channel to be used with or without TLS encryption. The
1796 options can be specified multiple times to configure multiple
1797 channels. The special name "default" can be used to set the default
1798 mode. For channels which are not explicitly forced into one mode the
1799 spice client is allowed to pick tls/plaintext as he pleases.
1801 @item image-compression=[auto_glz|auto_lz|quic|glz|lz|off]
1802 Configure image compression (lossless).
1803 Default is auto_glz.
1805 @item jpeg-wan-compression=[auto|never|always]
1806 @itemx zlib-glz-wan-compression=[auto|never|always]
1807 Configure wan image compression (lossy for slow links).
1810 @item streaming-video=[off|all|filter]
1811 Configure video stream detection. Default is off.
1813 @item agent-mouse=[on|off]
1814 Enable/disable passing mouse events via vdagent. Default is on.
1816 @item playback-compression=[on|off]
1817 Enable/disable audio stream compression (using celt 0.5.1). Default is on.
1819 @item seamless-migration=[on|off]
1820 Enable/disable spice seamless migration. Default is off.
1823 Enable/disable OpenGL context. Default is off.
1825 @item rendernode=<file>
1826 DRM render node for OpenGL rendering. If not specified, it will pick
1827 the first available. (Since 2.9)
1832 DEF("portrait", 0, QEMU_OPTION_portrait,
1833 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n",
1838 Rotate graphical output 90 deg left (only PXA LCD).
1841 DEF("rotate", HAS_ARG, QEMU_OPTION_rotate,
1842 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n",
1845 @item -rotate @var{deg}
1847 Rotate graphical output some deg left (only PXA LCD).
1850 DEF("vga", HAS_ARG, QEMU_OPTION_vga,
1851 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
1852 " select video card type\n", QEMU_ARCH_ALL)
1854 @item -vga @var{type}
1856 Select type of VGA card to emulate. Valid values for @var{type} are
1859 Cirrus Logic GD5446 Video card. All Windows versions starting from
1860 Windows 95 should recognize and use this graphic card. For optimal
1861 performances, use 16 bit color depth in the guest and the host OS.
1862 (This card was the default before QEMU 2.2)
1864 Standard VGA card with Bochs VBE extensions. If your guest OS
1865 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if you want
1866 to use high resolution modes (>= 1280x1024x16) then you should use
1867 this option. (This card is the default since QEMU 2.2)
1869 VMWare SVGA-II compatible adapter. Use it if you have sufficiently
1870 recent XFree86/XOrg server or Windows guest with a driver for this
1873 QXL paravirtual graphic card. It is VGA compatible (including VESA
1874 2.0 VBE support). Works best with qxl guest drivers installed though.
1875 Recommended choice when using the spice protocol.
1877 (sun4m only) Sun TCX framebuffer. This is the default framebuffer for
1878 sun4m machines and offers both 8-bit and 24-bit colour depths at a
1879 fixed resolution of 1024x768.
1881 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit framebuffer
1882 for sun4m machines available in both 1024x768 (OpenBIOS) and 1152x900 (OBP)
1883 resolutions aimed at people wishing to run older Solaris versions.
1891 DEF("full-screen", 0, QEMU_OPTION_full_screen,
1892 "-full-screen start in full screen\n", QEMU_ARCH_ALL)
1895 @findex -full-screen
1896 Start in full screen.
1899 DEF("g", 1, QEMU_OPTION_g ,
1900 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n",
1901 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K)
1903 @item -g @var{width}x@var{height}[x@var{depth}]
1905 Set the initial graphical resolution and depth (PPC, SPARC only).
1908 DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
1909 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
1911 @item -vnc @var{display}[,@var{option}[,@var{option}[,...]]]
1913 Normally, if QEMU is compiled with graphical window support, it displays
1914 output such as guest graphics, guest console, and the QEMU monitor in a
1915 window. With this option, you can have QEMU listen on VNC display
1916 @var{display} and redirect the VGA display over the VNC session. It is
1917 very useful to enable the usb tablet device when using this option
1918 (option @option{-device usb-tablet}). When using the VNC display, you
1919 must use the @option{-k} parameter to set the keyboard layout if you are
1920 not using en-us. Valid syntax for the @var{display} is
1926 With this option, QEMU will try next available VNC @var{display}s, until the
1927 number @var{L}, if the origianlly defined "-vnc @var{display}" is not
1928 available, e.g. port 5900+@var{display} is already used by another
1929 application. By default, to=0.
1931 @item @var{host}:@var{d}
1933 TCP connections will only be allowed from @var{host} on display @var{d}.
1934 By convention the TCP port is 5900+@var{d}. Optionally, @var{host} can
1935 be omitted in which case the server will accept connections from any host.
1937 @item unix:@var{path}
1939 Connections will be allowed over UNIX domain sockets where @var{path} is the
1940 location of a unix socket to listen for connections on.
1944 VNC is initialized but not started. The monitor @code{change} command
1945 can be used to later start the VNC server.
1949 Following the @var{display} value there may be one or more @var{option} flags
1950 separated by commas. Valid options are
1956 Connect to a listening VNC client via a ``reverse'' connection. The
1957 client is specified by the @var{display}. For reverse network
1958 connections (@var{host}:@var{d},@code{reverse}), the @var{d} argument
1959 is a TCP port number, not a display number.
1963 Opens an additional TCP listening port dedicated to VNC Websocket connections.
1964 If a bare @var{websocket} option is given, the Websocket port is
1965 5700+@var{display}. An alternative port can be specified with the
1966 syntax @code{websocket}=@var{port}.
1968 If @var{host} is specified connections will only be allowed from this host.
1969 It is possible to control the websocket listen address independently, using
1970 the syntax @code{websocket}=@var{host}:@var{port}.
1972 If no TLS credentials are provided, the websocket connection runs in
1973 unencrypted mode. If TLS credentials are provided, the websocket connection
1974 requires encrypted client connections.
1978 Require that password based authentication is used for client connections.
1980 The password must be set separately using the @code{set_password} command in
1981 the @ref{pcsys_monitor}. The syntax to change your password is:
1982 @code{set_password <protocol> <password>} where <protocol> could be either
1985 If you would like to change <protocol> password expiration, you should use
1986 @code{expire_password <protocol> <expiration-time>} where expiration time could
1987 be one of the following options: now, never, +seconds or UNIX time of
1988 expiration, e.g. +60 to make password expire in 60 seconds, or 1335196800
1989 to make password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for this
1992 You can also use keywords "now" or "never" for the expiration time to
1993 allow <protocol> password to expire immediately or never expire.
1995 @item tls-creds=@var{ID}
1997 Provides the ID of a set of TLS credentials to use to secure the
1998 VNC server. They will apply to both the normal VNC server socket
1999 and the websocket socket (if enabled). Setting TLS credentials
2000 will cause the VNC server socket to enable the VeNCrypt auth
2001 mechanism. The credentials should have been previously created
2002 using the @option{-object tls-creds} argument.
2004 @item tls-authz=@var{ID}
2006 Provides the ID of the QAuthZ authorization object against which
2007 the client's x509 distinguished name will validated. This object is
2008 only resolved at time of use, so can be deleted and recreated on the
2009 fly while the VNC server is active. If missing, it will default
2014 Require that the client use SASL to authenticate with the VNC server.
2015 The exact choice of authentication method used is controlled from the
2016 system / user's SASL configuration file for the 'qemu' service. This
2017 is typically found in /etc/sasl2/qemu.conf. If running QEMU as an
2018 unprivileged user, an environment variable SASL_CONF_PATH can be used
2019 to make it search alternate locations for the service config.
2020 While some SASL auth methods can also provide data encryption (eg GSSAPI),
2021 it is recommended that SASL always be combined with the 'tls' and
2022 'x509' settings to enable use of SSL and server certificates. This
2023 ensures a data encryption preventing compromise of authentication
2024 credentials. See the @ref{vnc_security} section for details on using
2025 SASL authentication.
2027 @item sasl-authz=@var{ID}
2029 Provides the ID of the QAuthZ authorization object against which
2030 the client's SASL username will validated. This object is
2031 only resolved at time of use, so can be deleted and recreated on the
2032 fly while the VNC server is active. If missing, it will default
2037 Legacy method for enabling authorization of clients against the
2038 x509 distinguished name and SASL username. It results in the creation
2039 of two @code{authz-list} objects with IDs of @code{vnc.username} and
2040 @code{vnc.x509dname}. The rules for these objects must be configured
2041 with the HMP ACL commands.
2043 This option is deprecated and should no longer be used. The new
2044 @option{sasl-authz} and @option{tls-authz} options are a
2049 Enable lossy compression methods (gradient, JPEG, ...). If this
2050 option is set, VNC client may receive lossy framebuffer updates
2051 depending on its encoding settings. Enabling this option can save
2052 a lot of bandwidth at the expense of quality.
2056 Disable adaptive encodings. Adaptive encodings are enabled by default.
2057 An adaptive encoding will try to detect frequently updated screen regions,
2058 and send updates in these regions using a lossy encoding (like JPEG).
2059 This can be really helpful to save bandwidth when playing videos. Disabling
2060 adaptive encodings restores the original static behavior of encodings
2063 @item share=[allow-exclusive|force-shared|ignore]
2065 Set display sharing policy. 'allow-exclusive' allows clients to ask
2066 for exclusive access. As suggested by the rfb spec this is
2067 implemented by dropping other connections. Connecting multiple
2068 clients in parallel requires all clients asking for a shared session
2069 (vncviewer: -shared switch). This is the default. 'force-shared'
2070 disables exclusive client access. Useful for shared desktop sessions,
2071 where you don't want someone forgetting specify -shared disconnect
2072 everybody else. 'ignore' completely ignores the shared flag and
2073 allows everybody connect unconditionally. Doesn't conform to the rfb
2074 spec but is traditional QEMU behavior.
2078 Set keyboard delay, for key down and key up events, in milliseconds.
2079 Default is 10. Keyboards are low-bandwidth devices, so this slowdown
2080 can help the device and guest to keep up and not lose events in case
2081 events are arriving in bulk. Possible causes for the latter are flaky
2082 network connections, or scripts for automated testing.
2084 @item audiodev=@var{audiodev}
2086 Use the specified @var{audiodev} when the VNC client requests audio
2087 transmission. When not using an -audiodev argument, this option must
2088 be omitted, otherwise is must be present and specify a valid audiodev.
2096 ARCHHEADING(, QEMU_ARCH_I386)
2098 ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2103 DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2104 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n",
2109 Use it when installing Windows 2000 to avoid a disk full bug. After
2110 Windows 2000 is installed, you no longer need this option (this option
2111 slows down the IDE transfers).
2114 DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2115 "-no-fd-bootchk disable boot signature checking for floppy disks\n",
2118 @item -no-fd-bootchk
2119 @findex -no-fd-bootchk
2120 Disable boot signature checking for floppy disks in BIOS. May
2121 be needed to boot from old floppy disks.
2124 DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
2125 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2129 Disable ACPI (Advanced Configuration and Power Interface) support. Use
2130 it if your guest OS complains about ACPI problems (PC target machine
2134 DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
2135 "-no-hpet disable HPET\n", QEMU_ARCH_I386)
2139 Disable HPET support.
2142 DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2143 "-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"
2144 " ACPI table description\n", QEMU_ARCH_I386)
2146 @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}]...]
2148 Add ACPI table with specified header fields and context from specified files.
2149 For file=, take whole ACPI table from the specified files, including all
2150 ACPI headers (possible overridden by other options).
2151 For data=, only data
2152 portion of the table is used, all header information is specified in the
2154 If a SLIC table is supplied to QEMU, then the SLIC's oem_id and oem_table_id
2155 fields will override the same in the RSDT and the FADT (a.k.a. FACP), in order
2156 to ensure the field matches required by the Microsoft SLIC spec and the ACPI
2160 DEF("smbios", HAS_ARG, QEMU_OPTION_smbios,
2161 "-smbios file=binary\n"
2162 " load SMBIOS entry from binary file\n"
2163 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2165 " specify SMBIOS type 0 fields\n"
2166 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2167 " [,uuid=uuid][,sku=str][,family=str]\n"
2168 " specify SMBIOS type 1 fields\n"
2169 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2170 " [,asset=str][,location=str]\n"
2171 " specify SMBIOS type 2 fields\n"
2172 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2174 " specify SMBIOS type 3 fields\n"
2175 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2176 " [,asset=str][,part=str]\n"
2177 " specify SMBIOS type 4 fields\n"
2178 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2179 " [,asset=str][,part=str][,speed=%d]\n"
2180 " specify SMBIOS type 17 fields\n",
2181 QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2183 @item -smbios file=@var{binary}
2185 Load SMBIOS entry from binary file.
2187 @item -smbios type=0[,vendor=@var{str}][,version=@var{str}][,date=@var{str}][,release=@var{%d.%d}][,uefi=on|off]
2188 Specify SMBIOS type 0 fields
2190 @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}]
2191 Specify SMBIOS type 1 fields
2193 @item -smbios type=2[,manufacturer=@var{str}][,product=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,location=@var{str}]
2194 Specify SMBIOS type 2 fields
2196 @item -smbios type=3[,manufacturer=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,sku=@var{str}]
2197 Specify SMBIOS type 3 fields
2199 @item -smbios type=4[,sock_pfx=@var{str}][,manufacturer=@var{str}][,version=@var{str}][,serial=@var{str}][,asset=@var{str}][,part=@var{str}]
2200 Specify SMBIOS type 4 fields
2202 @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}]
2203 Specify SMBIOS type 17 fields
2211 DEFHEADING(Network options:)
2216 DEF("netdev", HAS_ARG, QEMU_OPTION_netdev,
2218 "-netdev user,id=str[,ipv4[=on|off]][,net=addr[/mask]][,host=addr]\n"
2219 " [,ipv6[=on|off]][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2220 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2221 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2222 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2224 "[,smb=dir[,smbserver=addr]]\n"
2226 " configure a user mode network backend with ID 'str',\n"
2227 " its DHCP server and optional services\n"
2230 "-netdev tap,id=str,ifname=name\n"
2231 " configure a host TAP network backend with ID 'str'\n"
2233 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2234 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2235 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2237 " configure a host TAP network backend with ID 'str'\n"
2238 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2239 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n"
2240 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n"
2241 " to deconfigure it\n"
2242 " use '[down]script=no' to disable script execution\n"
2243 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n"
2245 " use 'fd=h' to connect to an already opened TAP interface\n"
2246 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2247 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2248 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2249 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2250 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2251 " use vhost=on to enable experimental in kernel accelerator\n"
2252 " (only has effect for virtio guests which use MSIX)\n"
2253 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2254 " use 'vhostfd=h' to connect to an already opened vhost net device\n"
2255 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2256 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2257 " use 'poll-us=n' to speciy the maximum number of microseconds that could be\n"
2258 " spent on busy polling for vhost net\n"
2259 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2260 " configure a host TAP network backend with ID 'str' that is\n"
2261 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n"
2262 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n"
2265 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2266 " [,rxsession=rxsession],txsession=txsession[,ipv6=on/off][,udp=on/off]\n"
2267 " [,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie]\n"
2268 " [,rxcookie=rxcookie][,offset=offset]\n"
2269 " configure a network backend with ID 'str' connected to\n"
2270 " an Ethernet over L2TPv3 pseudowire.\n"
2271 " Linux kernel 3.3+ as well as most routers can talk\n"
2272 " L2TPv3. This transport allows connecting a VM to a VM,\n"
2273 " VM to a router and even VM to Host. It is a nearly-universal\n"
2274 " standard (RFC3391). Note - this implementation uses static\n"
2275 " pre-configured tunnels (same as the Linux kernel).\n"
2276 " use 'src=' to specify source address\n"
2277 " use 'dst=' to specify destination address\n"
2278 " use 'udp=on' to specify udp encapsulation\n"
2279 " use 'srcport=' to specify source udp port\n"
2280 " use 'dstport=' to specify destination udp port\n"
2281 " use 'ipv6=on' to force v6\n"
2282 " L2TPv3 uses cookies to prevent misconfiguration as\n"
2283 " well as a weak security measure\n"
2284 " use 'rxcookie=0x012345678' to specify a rxcookie\n"
2285 " use 'txcookie=0x012345678' to specify a txcookie\n"
2286 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2287 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2288 " use 'pincounter=on' to work around broken counter handling in peer\n"
2289 " use 'offset=X' to add an extra offset between header and data\n"
2291 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2292 " configure a network backend to connect to another network\n"
2293 " using a socket connection\n"
2294 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2295 " configure a network backend to connect to a multicast maddr and port\n"
2296 " use 'localaddr=addr' to specify the host address to send packets from\n"
2297 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2298 " configure a network backend to connect to another network\n"
2299 " using an UDP tunnel\n"
2301 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2302 " configure a network backend to connect to port 'n' of a vde switch\n"
2303 " running on host and listening for incoming connections on 'socketpath'.\n"
2304 " Use group 'groupname' and mode 'octalmode' to change default\n"
2305 " ownership and permissions for communication port.\n"
2307 #ifdef CONFIG_NETMAP
2308 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2309 " attach to the existing netmap-enabled network interface 'name', or to a\n"
2310 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2311 " netmap device, defaults to '/dev/netmap')\n"
2314 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2315 " configure a vhost-user network, backed by a chardev 'dev'\n"
2317 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2318 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
2319 DEF("nic", HAS_ARG, QEMU_OPTION_nic,
2330 #ifdef CONFIG_NETMAP
2336 "socket][,option][,...][mac=macaddr]\n"
2337 " initialize an on-board / default host NIC (using MAC address\n"
2338 " macaddr) and connect it to the given host network backend\n"
2339 "-nic none use it alone to have zero network devices (the default is to\n"
2340 " provided a 'user' network connection)\n",
2342 DEF("net", HAS_ARG, QEMU_OPTION_net,
2343 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2344 " configure or create an on-board (or machine default) NIC and\n"
2345 " connect it to hub 0 (please use -nic unless you need a hub)\n"
2355 #ifdef CONFIG_NETMAP
2358 "socket][,option][,option][,...]\n"
2359 " old way to initialize a host network interface\n"
2360 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL)
2362 @item -nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]
2364 This option is a shortcut for configuring both the on-board (default) guest
2365 NIC hardware and the host network backend in one go. The host backend options
2366 are the same as with the corresponding @option{-netdev} options below.
2367 The guest NIC model can be set with @option{model=@var{modelname}}.
2368 Use @option{model=help} to list the available device types.
2369 The hardware MAC address can be set with @option{mac=@var{macaddr}}.
2371 The following two example do exactly the same, to show how @option{-nic} can
2372 be used to shorten the command line length (note that the e1000 is the default
2373 on i386, so the @option{model=e1000} parameter could even be omitted here, too):
2375 @value{qemu_system} -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32
2376 @value{qemu_system} -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32
2380 Indicate that no network devices should be configured. It is used to override
2381 the default configuration (default NIC with ``user'' host network backend)
2382 which is activated if no other networking options are provided.
2384 @item -netdev user,id=@var{id}[,@var{option}][,@var{option}][,...]
2386 Configure user mode host network backend which requires no administrator
2387 privilege to run. Valid options are:
2391 Assign symbolic name for use in monitor commands.
2393 @item ipv4=on|off and ipv6=on|off
2394 Specify that either IPv4 or IPv6 must be enabled. If neither is specified
2395 both protocols are enabled.
2397 @item net=@var{addr}[/@var{mask}]
2398 Set IP network address the guest will see. Optionally specify the netmask,
2399 either in the form a.b.c.d or as number of valid top-most bits. Default is
2402 @item host=@var{addr}
2403 Specify the guest-visible address of the host. Default is the 2nd IP in the
2404 guest network, i.e. x.x.x.2.
2406 @item ipv6-net=@var{addr}[/@var{int}]
2407 Set IPv6 network address the guest will see (default is fec0::/64). The
2408 network prefix is given in the usual hexadecimal IPv6 address
2409 notation. The prefix size is optional, and is given as the number of
2410 valid top-most bits (default is 64).
2412 @item ipv6-host=@var{addr}
2413 Specify the guest-visible IPv6 address of the host. Default is the 2nd IPv6 in
2414 the guest network, i.e. xxxx::2.
2416 @item restrict=on|off
2417 If this option is enabled, the guest will be isolated, i.e. it will not be
2418 able to contact the host and no guest IP packets will be routed over the host
2419 to the outside. This option does not affect any explicitly set forwarding rules.
2421 @item hostname=@var{name}
2422 Specifies the client hostname reported by the built-in DHCP server.
2424 @item dhcpstart=@var{addr}
2425 Specify the first of the 16 IPs the built-in DHCP server can assign. Default
2426 is the 15th to 31st IP in the guest network, i.e. x.x.x.15 to x.x.x.31.
2428 @item dns=@var{addr}
2429 Specify the guest-visible address of the virtual nameserver. The address must
2430 be different from the host address. Default is the 3rd IP in the guest network,
2433 @item ipv6-dns=@var{addr}
2434 Specify the guest-visible address of the IPv6 virtual nameserver. The address
2435 must be different from the host address. Default is the 3rd IP in the guest
2436 network, i.e. xxxx::3.
2438 @item dnssearch=@var{domain}
2439 Provides an entry for the domain-search list sent by the built-in
2440 DHCP server. More than one domain suffix can be transmitted by specifying
2441 this option multiple times. If supported, this will cause the guest to
2442 automatically try to append the given domain suffix(es) in case a domain name
2443 can not be resolved.
2447 @value{qemu_system} -nic user,dnssearch=mgmt.example.org,dnssearch=example.org
2450 @item domainname=@var{domain}
2451 Specifies the client domain name reported by the built-in DHCP server.
2453 @item tftp=@var{dir}
2454 When using the user mode network stack, activate a built-in TFTP
2455 server. The files in @var{dir} will be exposed as the root of a TFTP server.
2456 The TFTP client on the guest must be configured in binary mode (use the command
2457 @code{bin} of the Unix TFTP client).
2459 @item tftp-server-name=@var{name}
2460 In BOOTP reply, broadcast @var{name} as the "TFTP server name" (RFC2132 option
2461 66). This can be used to advise the guest to load boot files or configurations
2462 from a different server than the host address.
2464 @item bootfile=@var{file}
2465 When using the user mode network stack, broadcast @var{file} as the BOOTP
2466 filename. In conjunction with @option{tftp}, this can be used to network boot
2467 a guest from a local directory.
2469 Example (using pxelinux):
2471 @value{qemu_system} -hda linux.img -boot n -device e1000,netdev=n1 \
2472 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0
2475 @item smb=@var{dir}[,smbserver=@var{addr}]
2476 When using the user mode network stack, activate a built-in SMB
2477 server so that Windows OSes can access to the host files in @file{@var{dir}}
2478 transparently. The IP address of the SMB server can be set to @var{addr}. By
2479 default the 4th IP in the guest network is used, i.e. x.x.x.4.
2481 In the guest Windows OS, the line:
2485 must be added in the file @file{C:\WINDOWS\LMHOSTS} (for windows 9x/Me)
2486 or @file{C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS} (Windows NT/2000).
2488 Then @file{@var{dir}} can be accessed in @file{\\smbserver\qemu}.
2490 Note that a SAMBA server must be installed on the host OS.
2492 @item hostfwd=[tcp|udp]:[@var{hostaddr}]:@var{hostport}-[@var{guestaddr}]:@var{guestport}
2493 Redirect incoming TCP or UDP connections to the host port @var{hostport} to
2494 the guest IP address @var{guestaddr} on guest port @var{guestport}. If
2495 @var{guestaddr} is not specified, its value is x.x.x.15 (default first address
2496 given by the built-in DHCP server). By specifying @var{hostaddr}, the rule can
2497 be bound to a specific host interface. If no connection type is set, TCP is
2498 used. This option can be given multiple times.
2500 For example, to redirect host X11 connection from screen 1 to guest
2501 screen 0, use the following:
2505 @value{qemu_system} -nic user,hostfwd=tcp:127.0.0.1:6001-:6000
2506 # this host xterm should open in the guest X11 server
2510 To redirect telnet connections from host port 5555 to telnet port on
2511 the guest, use the following:
2515 @value{qemu_system} -nic user,hostfwd=tcp::5555-:23
2516 telnet localhost 5555
2519 Then when you use on the host @code{telnet localhost 5555}, you
2520 connect to the guest telnet server.
2522 @item guestfwd=[tcp]:@var{server}:@var{port}-@var{dev}
2523 @itemx guestfwd=[tcp]:@var{server}:@var{port}-@var{cmd:command}
2524 Forward guest TCP connections to the IP address @var{server} on port @var{port}
2525 to the character device @var{dev} or to a program executed by @var{cmd:command}
2526 which gets spawned for each connection. This option can be given multiple times.
2528 You can either use a chardev directly and have that one used throughout QEMU's
2529 lifetime, like in the following example:
2532 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
2533 # the guest accesses it
2534 @value{qemu_system} -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
2537 Or you can execute a command on every TCP connection established by the guest,
2538 so that QEMU behaves similar to an inetd process for that virtual server:
2541 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
2542 # and connect the TCP stream to its stdin/stdout
2543 @value{qemu_system} -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321'
2548 @item -netdev tap,id=@var{id}[,fd=@var{h}][,ifname=@var{name}][,script=@var{file}][,downscript=@var{dfile}][,br=@var{bridge}][,helper=@var{helper}]
2549 Configure a host TAP network backend with ID @var{id}.
2551 Use the network script @var{file} to configure it and the network script
2552 @var{dfile} to deconfigure it. If @var{name} is not provided, the OS
2553 automatically provides one. The default network configure script is
2554 @file{/etc/qemu-ifup} and the default network deconfigure script is
2555 @file{/etc/qemu-ifdown}. Use @option{script=no} or @option{downscript=no}
2556 to disable script execution.
2558 If running QEMU as an unprivileged user, use the network helper
2559 @var{helper} to configure the TAP interface and attach it to the bridge.
2560 The default network helper executable is @file{/path/to/qemu-bridge-helper}
2561 and the default bridge device is @file{br0}.
2563 @option{fd}=@var{h} can be used to specify the handle of an already
2564 opened host TAP interface.
2569 #launch a QEMU instance with the default network script
2570 @value{qemu_system} linux.img -nic tap
2574 #launch a QEMU instance with two NICs, each one connected
2576 @value{qemu_system} linux.img \
2577 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \
2578 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
2582 #launch a QEMU instance with the default network helper to
2583 #connect a TAP device to bridge br0
2584 @value{qemu_system} linux.img -device virtio-net-pci,netdev=n1 \
2585 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
2588 @item -netdev bridge,id=@var{id}[,br=@var{bridge}][,helper=@var{helper}]
2589 Connect a host TAP network interface to a host bridge device.
2591 Use the network helper @var{helper} to configure the TAP interface and
2592 attach it to the bridge. The default network helper executable is
2593 @file{/path/to/qemu-bridge-helper} and the default bridge
2594 device is @file{br0}.
2599 #launch a QEMU instance with the default network helper to
2600 #connect a TAP device to bridge br0
2601 @value{qemu_system} linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
2605 #launch a QEMU instance with the default network helper to
2606 #connect a TAP device to bridge qemubr0
2607 @value{qemu_system} linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
2610 @item -netdev socket,id=@var{id}[,fd=@var{h}][,listen=[@var{host}]:@var{port}][,connect=@var{host}:@var{port}]
2612 This host network backend can be used to connect the guest's network to
2613 another QEMU virtual machine using a TCP socket connection. If @option{listen}
2614 is specified, QEMU waits for incoming connections on @var{port}
2615 (@var{host} is optional). @option{connect} is used to connect to
2616 another QEMU instance using the @option{listen} option. @option{fd}=@var{h}
2617 specifies an already opened TCP socket.
2621 # launch a first 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,listen=:1234
2625 # connect the network of this instance to the network of the first instance
2626 @value{qemu_system} linux.img \
2627 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
2628 -netdev socket,id=n2,connect=127.0.0.1:1234
2631 @item -netdev socket,id=@var{id}[,fd=@var{h}][,mcast=@var{maddr}:@var{port}[,localaddr=@var{addr}]]
2633 Configure a socket host network backend to share the guest's network traffic
2634 with another QEMU virtual machines using a UDP multicast socket, effectively
2635 making a bus for every QEMU with same multicast address @var{maddr} and @var{port}.
2639 Several QEMU can be running on different hosts and share same bus (assuming
2640 correct multicast setup for these hosts).
2642 mcast support is compatible with User Mode Linux (argument @option{eth@var{N}=mcast}), see
2643 @url{http://user-mode-linux.sf.net}.
2645 Use @option{fd=h} to specify an already opened UDP multicast socket.
2650 # launch one QEMU instance
2651 @value{qemu_system} linux.img \
2652 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2653 -netdev socket,id=n1,mcast=230.0.0.1:1234
2654 # launch another QEMU instance on same "bus"
2655 @value{qemu_system} linux.img \
2656 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \
2657 -netdev socket,id=n2,mcast=230.0.0.1:1234
2658 # launch yet another QEMU instance on same "bus"
2659 @value{qemu_system} linux.img \
2660 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \
2661 -netdev socket,id=n3,mcast=230.0.0.1:1234
2664 Example (User Mode Linux compat.):
2666 # launch QEMU instance (note mcast address selected is UML's default)
2667 @value{qemu_system} linux.img \
2668 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2669 -netdev socket,id=n1,mcast=239.192.168.1:1102
2671 /path/to/linux ubd0=/path/to/root_fs eth0=mcast
2674 Example (send packets from host's 1.2.3.4):
2676 @value{qemu_system} linux.img \
2677 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \
2678 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
2681 @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}]
2682 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3391) is a
2683 popular protocol to transport Ethernet (and other Layer 2) data frames between
2684 two systems. It is present in routers, firewalls and the Linux kernel
2685 (from version 3.3 onwards).
2687 This transport allows a VM to communicate to another VM, router or firewall directly.
2690 @item src=@var{srcaddr}
2691 source address (mandatory)
2692 @item dst=@var{dstaddr}
2693 destination address (mandatory)
2695 select udp encapsulation (default is ip).
2696 @item srcport=@var{srcport}
2698 @item dstport=@var{dstport}
2699 destination udp port.
2701 force v6, otherwise defaults to v4.
2702 @item rxcookie=@var{rxcookie}
2703 @itemx txcookie=@var{txcookie}
2704 Cookies are a weak form of security in the l2tpv3 specification.
2705 Their function is mostly to prevent misconfiguration. By default they are 32
2708 Set cookie size to 64 bit instead of the default 32
2710 Force a 'cut-down' L2TPv3 with no counter as in
2711 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
2713 Work around broken counter handling in peer. This may also help on
2714 networks which have packet reorder.
2715 @item offset=@var{offset}
2716 Add an extra offset between header and data
2719 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to the bridge br-lan
2720 on the remote Linux host 1.2.3.4:
2722 # Setup tunnel on linux host using raw ip as encapsulation
2724 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \
2725 encap udp udp_sport 16384 udp_dport 16384
2726 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \
2727 0xFFFFFFFF peer_session_id 0xFFFFFFFF
2728 ifconfig vmtunnel0 mtu 1500
2729 ifconfig vmtunnel0 up
2730 brctl addif br-lan vmtunnel0
2734 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
2736 @value{qemu_system} linux.img -device e1000,netdev=n1 \
2737 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
2741 @item -netdev vde,id=@var{id}[,sock=@var{socketpath}][,port=@var{n}][,group=@var{groupname}][,mode=@var{octalmode}]
2742 Configure VDE backend to connect to PORT @var{n} of a vde switch running on host and
2743 listening for incoming connections on @var{socketpath}. Use GROUP @var{groupname}
2744 and MODE @var{octalmode} to change default ownership and permissions for
2745 communication port. This option is only available if QEMU has been compiled
2746 with vde support enabled.
2751 vde_switch -F -sock /tmp/myswitch
2752 # launch QEMU instance
2753 @value{qemu_system} linux.img -nic vde,sock=/tmp/myswitch
2756 @item -netdev vhost-user,chardev=@var{id}[,vhostforce=on|off][,queues=n]
2758 Establish a vhost-user netdev, backed by a chardev @var{id}. The chardev should
2759 be a unix domain socket backed one. The vhost-user uses a specifically defined
2760 protocol to pass vhost ioctl replacement messages to an application on the other
2761 end of the socket. On non-MSIX guests, the feature can be forced with
2762 @var{vhostforce}. Use 'queues=@var{n}' to specify the number of queues to
2763 be created for multiqueue vhost-user.
2767 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
2768 -numa node,memdev=mem \
2769 -chardev socket,id=chr0,path=/path/to/socket \
2770 -netdev type=vhost-user,id=net0,chardev=chr0 \
2771 -device virtio-net-pci,netdev=net0
2774 @item -netdev hubport,id=@var{id},hubid=@var{hubid}[,netdev=@var{nd}]
2776 Create a hub port on the emulated hub with ID @var{hubid}.
2778 The hubport netdev lets you connect a NIC to a QEMU emulated hub instead of a
2779 single netdev. Alternatively, you can also connect the hubport to another
2780 netdev with ID @var{nd} by using the @option{netdev=@var{nd}} option.
2782 @item -net nic[,netdev=@var{nd}][,macaddr=@var{mac}][,model=@var{type}] [,name=@var{name}][,addr=@var{addr}][,vectors=@var{v}]
2784 Legacy option to configure or create an on-board (or machine default) Network
2785 Interface Card(NIC) and connect it either to the emulated hub with ID 0 (i.e.
2786 the default hub), or to the netdev @var{nd}.
2787 The NIC is an e1000 by default on the PC target. Optionally, the MAC address
2788 can be changed to @var{mac}, the device address set to @var{addr} (PCI cards
2789 only), and a @var{name} can be assigned for use in monitor commands.
2790 Optionally, for PCI cards, you can specify the number @var{v} of MSI-X vectors
2791 that the card should have; this option currently only affects virtio cards; set
2792 @var{v} = 0 to disable MSI-X. If no @option{-net} option is specified, a single
2793 NIC is created. QEMU can emulate several different models of network card.
2794 Use @code{-net nic,model=help} for a list of available devices for your target.
2796 @item -net user|tap|bridge|socket|l2tpv3|vde[,...][,name=@var{name}]
2797 Configure a host network backend (with the options corresponding to the same
2798 @option{-netdev} option) and connect it to the emulated hub 0 (the default
2799 hub). Use @var{name} to specify the name of the hub port.
2807 DEFHEADING(Character device options:)
2809 DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
2811 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2812 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n"
2813 " [,server][,nowait][,telnet][,websocket][,reconnect=seconds][,mux=on|off]\n"
2814 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
2815 "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,websocket][,reconnect=seconds]\n"
2816 " [,mux=on|off][,logfile=PATH][,logappend=on|off] (unix)\n"
2817 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
2818 " [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n"
2819 " [,logfile=PATH][,logappend=on|off]\n"
2820 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2821 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
2822 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2823 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
2824 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2825 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2827 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2828 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2830 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2831 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
2833 #ifdef CONFIG_BRLAPI
2834 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2836 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
2837 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
2838 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2839 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2841 #if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
2842 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2843 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
2845 #if defined(CONFIG_SPICE)
2846 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
2847 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
2854 The general form of a character device option is:
2856 @item -chardev @var{backend},id=@var{id}[,mux=on|off][,@var{options}]
2877 The specific backend will determine the applicable options.
2879 Use @code{-chardev help} to print all available chardev backend types.
2881 All devices must have an id, which can be any string up to 127 characters long.
2882 It is used to uniquely identify this device in other command line directives.
2884 A character device may be used in multiplexing mode by multiple front-ends.
2885 Specify @option{mux=on} to enable this mode.
2886 A multiplexer is a "1:N" device, and here the "1" end is your specified chardev
2887 backend, and the "N" end is the various parts of QEMU that can talk to a chardev.
2888 If you create a chardev with @option{id=myid} and @option{mux=on}, QEMU will
2889 create a multiplexer with your specified ID, and you can then configure multiple
2890 front ends to use that chardev ID for their input/output. Up to four different
2891 front ends can be connected to a single multiplexed chardev. (Without
2892 multiplexing enabled, a chardev can only be used by a single front end.)
2893 For instance you could use this to allow a single stdio chardev to be used by
2894 two serial ports and the QEMU monitor:
2897 -chardev stdio,mux=on,id=char0 \
2898 -mon chardev=char0,mode=readline \
2899 -serial chardev:char0 \
2900 -serial chardev:char0
2903 You can have more than one multiplexer in a system configuration; for instance
2904 you could have a TCP port multiplexed between UART 0 and UART 1, and stdio
2905 multiplexed between the QEMU monitor and a parallel port:
2908 -chardev stdio,mux=on,id=char0 \
2909 -mon chardev=char0,mode=readline \
2910 -parallel chardev:char0 \
2911 -chardev tcp,...,mux=on,id=char1 \
2912 -serial chardev:char1 \
2913 -serial chardev:char1
2916 When you're using a multiplexed character device, some escape sequences are
2917 interpreted in the input. @xref{mux_keys, Keys in the character backend
2920 Note that some other command line options may implicitly create multiplexed
2921 character backends; for instance @option{-serial mon:stdio} creates a
2922 multiplexed stdio backend connected to the serial port and the QEMU monitor,
2923 and @option{-nographic} also multiplexes the console and the monitor to
2926 There is currently no support for multiplexing in the other direction
2927 (where a single QEMU front end takes input and output from multiple chardevs).
2929 Every backend supports the @option{logfile} option, which supplies the path
2930 to a file to record all data transmitted via the backend. The @option{logappend}
2931 option controls whether the log file will be truncated or appended to when
2936 The available backends are:
2939 @item -chardev null,id=@var{id}
2940 A void device. This device will not emit any data, and will drop any data it
2941 receives. The null backend does not take any options.
2943 @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}]
2945 Create a two-way stream socket, which can be either a TCP or a unix socket. A
2946 unix socket will be created if @option{path} is specified. Behaviour is
2947 undefined if TCP options are specified for a unix socket.
2949 @option{server} specifies that the socket shall be a listening socket.
2951 @option{nowait} specifies that QEMU should not block waiting for a client to
2952 connect to a listening socket.
2954 @option{telnet} specifies that traffic on the socket should interpret telnet
2957 @option{websocket} specifies that the socket uses WebSocket protocol for
2960 @option{reconnect} sets the timeout for reconnecting on non-server sockets when
2961 the remote end goes away. qemu will delay this many seconds and then attempt
2962 to reconnect. Zero disables reconnecting, and is the default.
2964 @option{tls-creds} requests enablement of the TLS protocol for encryption,
2965 and specifies the id of the TLS credentials to use for the handshake. The
2966 credentials must be previously created with the @option{-object tls-creds}
2969 @option{tls-auth} provides the ID of the QAuthZ authorization object against
2970 which the client's x509 distinguished name will be validated. This object is
2971 only resolved at time of use, so can be deleted and recreated on the fly
2972 while the chardev server is active. If missing, it will default to denying
2975 TCP and unix socket options are given below:
2979 @item TCP options: port=@var{port}[,host=@var{host}][,to=@var{to}][,ipv4][,ipv6][,nodelay]
2981 @option{host} for a listening socket specifies the local address to be bound.
2982 For a connecting socket species the remote host to connect to. @option{host} is
2983 optional for listening sockets. If not specified it defaults to @code{0.0.0.0}.
2985 @option{port} for a listening socket specifies the local port to be bound. For a
2986 connecting socket specifies the port on the remote host to connect to.
2987 @option{port} can be given as either a port number or a service name.
2988 @option{port} is required.
2990 @option{to} is only relevant to listening sockets. If it is specified, and
2991 @option{port} cannot be bound, QEMU will attempt to bind to subsequent ports up
2992 to and including @option{to} until it succeeds. @option{to} must be specified
2995 @option{ipv4} and @option{ipv6} specify that either IPv4 or IPv6 must be used.
2996 If neither is specified the socket may use either protocol.
2998 @option{nodelay} disables the Nagle algorithm.
3000 @item unix options: path=@var{path}
3002 @option{path} specifies the local path of the unix socket. @option{path} is
3007 @item -chardev udp,id=@var{id}[,host=@var{host}],port=@var{port}[,localaddr=@var{localaddr}][,localport=@var{localport}][,ipv4][,ipv6]
3009 Sends all traffic from the guest to a remote host over UDP.
3011 @option{host} specifies the remote host to connect to. If not specified it
3012 defaults to @code{localhost}.
3014 @option{port} specifies the port on the remote host to connect to. @option{port}
3017 @option{localaddr} specifies the local address to bind to. If not specified it
3018 defaults to @code{0.0.0.0}.
3020 @option{localport} specifies the local port to bind to. If not specified any
3021 available local port will be used.
3023 @option{ipv4} and @option{ipv6} specify that either IPv4 or IPv6 must be used.
3024 If neither is specified the device may use either protocol.
3026 @item -chardev msmouse,id=@var{id}
3028 Forward QEMU's emulated msmouse events to the guest. @option{msmouse} does not
3031 @item -chardev vc,id=@var{id}[[,width=@var{width}][,height=@var{height}]][[,cols=@var{cols}][,rows=@var{rows}]]
3033 Connect to a QEMU text console. @option{vc} may optionally be given a specific
3036 @option{width} and @option{height} specify the width and height respectively of
3037 the console, in pixels.
3039 @option{cols} and @option{rows} specify that the console be sized to fit a text
3040 console with the given dimensions.
3042 @item -chardev ringbuf,id=@var{id}[,size=@var{size}]
3044 Create a ring buffer with fixed size @option{size}.
3045 @var{size} must be a power of two and defaults to @code{64K}.
3047 @item -chardev file,id=@var{id},path=@var{path}
3049 Log all traffic received from the guest to a file.
3051 @option{path} specifies the path of the file to be opened. This file will be
3052 created if it does not already exist, and overwritten if it does. @option{path}
3055 @item -chardev pipe,id=@var{id},path=@var{path}
3057 Create a two-way connection to the guest. The behaviour differs slightly between
3058 Windows hosts and other hosts:
3060 On Windows, a single duplex pipe will be created at
3061 @file{\\.pipe\@option{path}}.
3063 On other hosts, 2 pipes will be created called @file{@option{path}.in} and
3064 @file{@option{path}.out}. Data written to @file{@option{path}.in} will be
3065 received by the guest. Data written by the guest can be read from
3066 @file{@option{path}.out}. QEMU will not create these fifos, and requires them to
3069 @option{path} forms part of the pipe path as described above. @option{path} is
3072 @item -chardev console,id=@var{id}
3074 Send traffic from the guest to QEMU's standard output. @option{console} does not
3077 @option{console} is only available on Windows hosts.
3079 @item -chardev serial,id=@var{id},path=@option{path}
3081 Send traffic from the guest to a serial device on the host.
3083 On Unix hosts serial will actually accept any tty device,
3084 not only serial lines.
3086 @option{path} specifies the name of the serial device to open.
3088 @item -chardev pty,id=@var{id}
3090 Create a new pseudo-terminal on the host and connect to it. @option{pty} does
3091 not take any options.
3093 @option{pty} is not available on Windows hosts.
3095 @item -chardev stdio,id=@var{id}[,signal=on|off]
3096 Connect to standard input and standard output of the QEMU process.
3098 @option{signal} controls if signals are enabled on the terminal, that includes
3099 exiting QEMU with the key sequence @key{Control-c}. This option is enabled by
3100 default, use @option{signal=off} to disable it.
3102 @item -chardev braille,id=@var{id}
3104 Connect to a local BrlAPI server. @option{braille} does not take any options.
3106 @item -chardev tty,id=@var{id},path=@var{path}
3108 @option{tty} is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD and
3109 DragonFlyBSD hosts. It is an alias for @option{serial}.
3111 @option{path} specifies the path to the tty. @option{path} is required.
3113 @item -chardev parallel,id=@var{id},path=@var{path}
3114 @itemx -chardev parport,id=@var{id},path=@var{path}
3116 @option{parallel} is only available on Linux, FreeBSD and DragonFlyBSD hosts.
3118 Connect to a local parallel port.
3120 @option{path} specifies the path to the parallel port device. @option{path} is
3123 @item -chardev spicevmc,id=@var{id},debug=@var{debug},name=@var{name}
3125 @option{spicevmc} is only available when spice support is built in.
3127 @option{debug} debug level for spicevmc
3129 @option{name} name of spice channel to connect to
3131 Connect to a spice virtual machine channel, such as vdiport.
3133 @item -chardev spiceport,id=@var{id},debug=@var{debug},name=@var{name}
3135 @option{spiceport} is only available when spice support is built in.
3137 @option{debug} debug level for spicevmc
3139 @option{name} name of spice port to connect to
3141 Connect to a spice port, allowing a Spice client to handle the traffic
3142 identified by a name (preferably a fqdn).
3151 DEFHEADING(TPM device options:)
3153 DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3154 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3155 " use path to provide path to a character device; default is /dev/tpm0\n"
3156 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n"
3157 " not provided it will be searched for in /sys/class/misc/tpm?/device\n"
3158 "-tpmdev emulator,id=id,chardev=dev\n"
3159 " configure the TPM device using chardev backend\n",
3163 The general form of a TPM device option is:
3166 @item -tpmdev @var{backend},id=@var{id}[,@var{options}]
3169 The specific backend type will determine the applicable options.
3170 The @code{-tpmdev} option creates the TPM backend and requires a
3171 @code{-device} option that specifies the TPM frontend interface model.
3173 Use @code{-tpmdev help} to print all available TPM backend types.
3177 The available backends are:
3181 @item -tpmdev passthrough,id=@var{id},path=@var{path},cancel-path=@var{cancel-path}
3183 (Linux-host only) Enable access to the host's TPM using the passthrough
3186 @option{path} specifies the path to the host's TPM device, i.e., on
3187 a Linux host this would be @code{/dev/tpm0}.
3188 @option{path} is optional and by default @code{/dev/tpm0} is used.
3190 @option{cancel-path} specifies the path to the host TPM device's sysfs
3191 entry allowing for cancellation of an ongoing TPM command.
3192 @option{cancel-path} is optional and by default QEMU will search for the
3195 Some notes about using the host's TPM with the passthrough driver:
3197 The TPM device accessed by the passthrough driver must not be
3198 used by any other application on the host.
3200 Since the host's firmware (BIOS/UEFI) has already initialized the TPM,
3201 the VM's firmware (BIOS/UEFI) will not be able to initialize the
3202 TPM again and may therefore not show a TPM-specific menu that would
3203 otherwise allow the user to configure the TPM, e.g., allow the user to
3204 enable/disable or activate/deactivate the TPM.
3205 Further, if TPM ownership is released from within a VM then the host's TPM
3206 will get disabled and deactivated. To enable and activate the
3207 TPM again afterwards, the host has to be rebooted and the user is
3208 required to enter the firmware's menu to enable and activate the TPM.
3209 If the TPM is left disabled and/or deactivated most TPM commands will fail.
3211 To create a passthrough TPM use the following two options:
3213 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3215 Note that the @code{-tpmdev} id is @code{tpm0} and is referenced by
3216 @code{tpmdev=tpm0} in the device option.
3218 @item -tpmdev emulator,id=@var{id},chardev=@var{dev}
3220 (Linux-host only) Enable access to a TPM emulator using Unix domain socket based
3223 @option{chardev} specifies the unique ID of a character device backend that provides connection to the software TPM server.
3225 To create a TPM emulator backend device with chardev socket backend:
3228 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3241 DEFHEADING(Linux/Multiboot boot specific:)
3244 When using these options, you can use a given Linux or Multiboot
3245 kernel without installing it in the disk image. It can be useful
3246 for easier testing of various kernels.
3251 DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \
3252 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL)
3254 @item -kernel @var{bzImage}
3256 Use @var{bzImage} as kernel image. The kernel can be either a Linux kernel
3257 or in multiboot format.
3260 DEF("append", HAS_ARG, QEMU_OPTION_append, \
3261 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL)
3263 @item -append @var{cmdline}
3265 Use @var{cmdline} as kernel command line
3268 DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
3269 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
3271 @item -initrd @var{file}
3273 Use @var{file} as initial ram disk.
3275 @item -initrd "@var{file1} arg=foo,@var{file2}"
3277 This syntax is only available with multiboot.
3279 Use @var{file1} and @var{file2} as modules and pass arg=foo as parameter to the
3283 DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
3284 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL)
3286 @item -dtb @var{file}
3288 Use @var{file} as a device tree binary (dtb) image and pass it to the kernel
3297 DEFHEADING(Debug/Expert options:)
3302 DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg,
3303 "-fw_cfg [name=]<name>,file=<file>\n"
3304 " add named fw_cfg entry with contents from file\n"
3305 "-fw_cfg [name=]<name>,string=<str>\n"
3306 " add named fw_cfg entry with contents from string\n",
3310 @item -fw_cfg [name=]@var{name},file=@var{file}
3312 Add named fw_cfg entry with contents from file @var{file}.
3314 @item -fw_cfg [name=]@var{name},string=@var{str}
3315 Add named fw_cfg entry with contents from string @var{str}.
3317 The terminating NUL character of the contents of @var{str} will not be
3318 included as part of the fw_cfg item data. To insert contents with
3319 embedded NUL characters, you have to use the @var{file} parameter.
3321 The fw_cfg entries are passed by QEMU through to the guest.
3325 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
3327 creates an fw_cfg entry named opt/com.mycompany/blob with contents
3332 DEF("serial", HAS_ARG, QEMU_OPTION_serial, \
3333 "-serial dev redirect the serial port to char device 'dev'\n",
3336 @item -serial @var{dev}
3338 Redirect the virtual serial port to host character device
3339 @var{dev}. The default device is @code{vc} in graphical mode and
3340 @code{stdio} in non graphical mode.
3342 This option can be used several times to simulate up to 4 serial
3345 Use @code{-serial none} to disable all serial ports.
3347 Available character devices are:
3349 @item vc[:@var{W}x@var{H}]
3350 Virtual console. Optionally, a width and height can be given in pixel with
3354 It is also possible to specify width or height in characters:
3359 [Linux only] Pseudo TTY (a new PTY is automatically allocated)
3361 No device is allocated.
3364 @item chardev:@var{id}
3365 Use a named character device defined with the @code{-chardev} option.
3367 [Linux only] Use host tty, e.g. @file{/dev/ttyS0}. The host serial port
3368 parameters are set according to the emulated ones.
3369 @item /dev/parport@var{N}
3370 [Linux only, parallel port only] Use host parallel port
3371 @var{N}. Currently SPP and EPP parallel port features can be used.
3372 @item file:@var{filename}
3373 Write output to @var{filename}. No character can be read.
3375 [Unix only] standard input/output
3376 @item pipe:@var{filename}
3377 name pipe @var{filename}
3379 [Windows only] Use host serial port @var{n}
3380 @item udp:[@var{remote_host}]:@var{remote_port}[@@[@var{src_ip}]:@var{src_port}]
3381 This implements UDP Net Console.
3382 When @var{remote_host} or @var{src_ip} are not specified
3383 they default to @code{0.0.0.0}.
3384 When not using a specified @var{src_port} a random port is automatically chosen.
3386 If you just want a simple readonly console you can use @code{netcat} or
3387 @code{nc}, by starting QEMU with: @code{-serial udp::4555} and nc as:
3388 @code{nc -u -l -p 4555}. Any time QEMU writes something to that port it
3389 will appear in the netconsole session.
3391 If you plan to send characters back via netconsole or you want to stop
3392 and start QEMU a lot of times, you should have QEMU use the same
3393 source port each time by using something like @code{-serial
3394 udp::4555@@:4556} to QEMU. Another approach is to use a patched
3395 version of netcat which can listen to a TCP port and send and receive
3396 characters via udp. If you have a patched version of netcat which
3397 activates telnet remote echo and single char transfer, then you can
3398 use the following options to set up a netcat redirector to allow
3399 telnet on port 5555 to access the QEMU port.
3402 -serial udp::4555@@:4556
3403 @item netcat options:
3404 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
3405 @item telnet options:
3409 @item tcp:[@var{host}]:@var{port}[,@var{server}][,nowait][,nodelay][,reconnect=@var{seconds}]
3410 The TCP Net Console has two modes of operation. It can send the serial
3411 I/O to a location or wait for a connection from a location. By default
3412 the TCP Net Console is sent to @var{host} at the @var{port}. If you use
3413 the @var{server} option QEMU will wait for a client socket application
3414 to connect to the port before continuing, unless the @code{nowait}
3415 option was specified. The @code{nodelay} option disables the Nagle buffering
3416 algorithm. The @code{reconnect} option only applies if @var{noserver} is
3417 set, if the connection goes down it will attempt to reconnect at the
3418 given interval. If @var{host} is omitted, 0.0.0.0 is assumed. Only
3419 one TCP connection at a time is accepted. You can use @code{telnet} to
3420 connect to the corresponding character device.
3422 @item Example to send tcp console to 192.168.0.2 port 4444
3423 -serial tcp:192.168.0.2:4444
3424 @item Example to listen and wait on port 4444 for connection
3425 -serial tcp::4444,server
3426 @item Example to not wait and listen on ip 192.168.0.100 port 4444
3427 -serial tcp:192.168.0.100:4444,server,nowait
3430 @item telnet:@var{host}:@var{port}[,server][,nowait][,nodelay]
3431 The telnet protocol is used instead of raw tcp sockets. The options
3432 work the same as if you had specified @code{-serial tcp}. The
3433 difference is that the port acts like a telnet server or client using
3434 telnet option negotiation. This will also allow you to send the
3435 MAGIC_SYSRQ sequence if you use a telnet that supports sending the break
3436 sequence. Typically in unix telnet you do it with Control-] and then
3437 type "send break" followed by pressing the enter key.
3439 @item websocket:@var{host}:@var{port},server[,nowait][,nodelay]
3440 The WebSocket protocol is used instead of raw tcp socket. The port acts as
3441 a WebSocket server. Client mode is not supported.
3443 @item unix:@var{path}[,server][,nowait][,reconnect=@var{seconds}]
3444 A unix domain socket is used instead of a tcp socket. The option works the
3445 same as if you had specified @code{-serial tcp} except the unix domain socket
3446 @var{path} is used for connections.
3448 @item mon:@var{dev_string}
3449 This is a special option to allow the monitor to be multiplexed onto
3450 another serial port. The monitor is accessed with key sequence of
3451 @key{Control-a} and then pressing @key{c}.
3452 @var{dev_string} should be any one of the serial devices specified
3453 above. An example to multiplex the monitor onto a telnet server
3454 listening on port 4444 would be:
3456 @item -serial mon:telnet::4444,server,nowait
3458 When the monitor is multiplexed to stdio in this way, Ctrl+C will not terminate
3459 QEMU any more but will be passed to the guest instead.
3462 Braille device. This will use BrlAPI to display the braille output on a real
3466 Three button serial mouse. Configure the guest to use Microsoft protocol.
3470 DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \
3471 "-parallel dev redirect the parallel port to char device 'dev'\n",
3474 @item -parallel @var{dev}
3476 Redirect the virtual parallel port to host device @var{dev} (same
3477 devices as the serial port). On Linux hosts, @file{/dev/parportN} can
3478 be used to use hardware devices connected on the corresponding host
3481 This option can be used several times to simulate up to 3 parallel
3484 Use @code{-parallel none} to disable all parallel ports.
3487 DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \
3488 "-monitor dev redirect the monitor to char device 'dev'\n",
3491 @item -monitor @var{dev}
3493 Redirect the monitor to host device @var{dev} (same devices as the
3495 The default device is @code{vc} in graphical mode and @code{stdio} in
3497 Use @code{-monitor none} to disable the default monitor.
3499 DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \
3500 "-qmp dev like -monitor but opens in 'control' mode\n",
3503 @item -qmp @var{dev}
3505 Like -monitor but opens in 'control' mode.
3507 DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \
3508 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n",
3511 @item -qmp-pretty @var{dev}
3513 Like -qmp but uses pretty JSON formatting.
3516 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
3517 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL)
3519 @item -mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]
3521 Setup monitor on chardev @var{name}. @code{pretty} turns on JSON pretty printing
3522 easing human reading and debugging.
3525 DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \
3526 "-debugcon dev redirect the debug console to char device 'dev'\n",
3529 @item -debugcon @var{dev}
3531 Redirect the debug console to host device @var{dev} (same devices as the
3532 serial port). The debug console is an I/O port which is typically port
3533 0xe9; writing to that I/O port sends output to this device.
3534 The default device is @code{vc} in graphical mode and @code{stdio} in
3538 DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \
3539 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL)
3541 @item -pidfile @var{file}
3543 Store the QEMU process PID in @var{file}. It is useful if you launch QEMU
3547 DEF("singlestep", 0, QEMU_OPTION_singlestep, \
3548 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL)
3552 Run the emulation in single step mode.
3555 DEF("preconfig", 0, QEMU_OPTION_preconfig, \
3556 "--preconfig pause QEMU before machine is initialized (experimental)\n",
3561 Pause QEMU for interactive configuration before the machine is created,
3562 which allows querying and configuring properties that will affect
3563 machine initialization. Use QMP command 'x-exit-preconfig' to exit
3564 the preconfig state and move to the next state (i.e. run guest if -S
3565 isn't used or pause the second time if -S is used). This option is
3569 DEF("S", 0, QEMU_OPTION_S, \
3570 "-S freeze CPU at startup (use 'c' to start execution)\n",
3575 Do not start CPU at startup (you must type 'c' in the monitor).
3578 DEF("realtime", HAS_ARG, QEMU_OPTION_realtime,
3579 "-realtime [mlock=on|off]\n"
3580 " run qemu with realtime features\n"
3581 " mlock=on|off controls mlock support (default: on)\n",
3584 @item -realtime mlock=on|off
3586 Run qemu with realtime features.
3587 mlocking qemu and guest memory can be enabled via @option{mlock=on}
3588 (enabled by default).
3591 DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit,
3592 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n"
3593 " run qemu with overcommit hints\n"
3594 " mem-lock=on|off controls memory lock support (default: off)\n"
3595 " cpu-pm=on|off controls cpu power management (default: off)\n",
3598 @item -overcommit mem-lock=on|off
3599 @item -overcommit cpu-pm=on|off
3601 Run qemu with hints about host resource overcommit. The default is
3602 to assume that host overcommits all resources.
3604 Locking qemu and guest memory can be enabled via @option{mem-lock=on} (disabled
3605 by default). This works when host memory is not overcommitted and reduces the
3606 worst-case latency for guest. This is equivalent to @option{realtime}.
3608 Guest ability to manage power state of host cpus (increasing latency for other
3609 processes on the same host cpu, but decreasing latency for guest) can be
3610 enabled via @option{cpu-pm=on} (disabled by default). This works best when
3611 host CPU is not overcommitted. When used, host estimates of CPU cycle and power
3612 utilization will be incorrect, not taking into account guest idle time.
3615 DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \
3616 "-gdb dev wait for gdb connection on 'dev'\n", QEMU_ARCH_ALL)
3618 @item -gdb @var{dev}
3620 Wait for gdb connection on device @var{dev} (@pxref{gdb_usage}). Typical
3621 connections will likely be TCP-based, but also UDP, pseudo TTY, or even
3622 stdio are reasonable use case. The latter is allowing to start QEMU from
3623 within gdb and establish the connection via a pipe:
3625 (gdb) target remote | exec @value{qemu_system} -gdb stdio ...
3629 DEF("s", 0, QEMU_OPTION_s, \
3630 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n",
3635 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
3636 (@pxref{gdb_usage}).
3639 DEF("d", HAS_ARG, QEMU_OPTION_d, \
3640 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n",
3643 @item -d @var{item1}[,...]
3645 Enable logging of specified items. Use '-d help' for a list of log items.
3648 DEF("D", HAS_ARG, QEMU_OPTION_D, \
3649 "-D logfile output log to logfile (default stderr)\n",
3652 @item -D @var{logfile}
3654 Output log in @var{logfile} instead of to stderr
3657 DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
3658 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
3661 @item -dfilter @var{range1}[,...]
3663 Filter debug output to that relevant to a range of target addresses. The filter
3664 spec can be either @var{start}+@var{size}, @var{start}-@var{size} or
3665 @var{start}..@var{end} where @var{start} @var{end} and @var{size} are the
3666 addresses and sizes required. For example:
3668 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
3670 Will dump output for any code in the 0x1000 sized block starting at 0x8000 and
3671 the 0x200 sized block starting at 0xffffffc000080000 and another 0x1000 sized
3672 block starting at 0xffffffc00005f000.
3675 DEF("seed", HAS_ARG, QEMU_OPTION_seed, \
3676 "-seed number seed the pseudo-random number generator\n",
3679 @item -seed @var{number}
3681 Force the guest to use a deterministic pseudo-random number generator, seeded
3682 with @var{number}. This does not affect crypto routines within the host.
3685 DEF("L", HAS_ARG, QEMU_OPTION_L, \
3686 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n",
3691 Set the directory for the BIOS, VGA BIOS and keymaps.
3693 To list all the data directories, use @code{-L help}.
3696 DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
3697 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL)
3699 @item -bios @var{file}
3701 Set the filename for the BIOS.
3704 DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
3705 "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ALL)
3709 Enable KVM full virtualization support. This option is only available
3710 if KVM support is enabled when compiling.
3713 DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid,
3714 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL)
3715 DEF("xen-attach", 0, QEMU_OPTION_xen_attach,
3716 "-xen-attach attach to existing xen domain\n"
3717 " libxl will use this when starting QEMU\n",
3719 DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict,
3720 "-xen-domid-restrict restrict set of available xen operations\n"
3721 " to specified domain id. (Does not affect\n"
3722 " xenpv machine type).\n",
3725 @item -xen-domid @var{id}
3727 Specify xen guest domain @var{id} (XEN only).
3730 Attach to existing xen domain.
3731 libxl will use this when starting QEMU (XEN only).
3732 @findex -xen-domid-restrict
3733 Restrict set of available xen operations to specified domain id (XEN only).
3736 DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \
3737 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL)
3741 Exit instead of rebooting.
3744 DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \
3745 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL)
3748 @findex -no-shutdown
3749 Don't exit QEMU on guest shutdown, but instead only stop the emulation.
3750 This allows for instance switching to monitor to commit changes to the
3754 DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \
3755 "-loadvm [tag|id]\n" \
3756 " start right away with a saved state (loadvm in monitor)\n",
3759 @item -loadvm @var{file}
3761 Start right away with a saved state (@code{loadvm} in monitor)
3765 DEF("daemonize", 0, QEMU_OPTION_daemonize, \
3766 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL)
3771 Daemonize the QEMU process after initialization. QEMU will not detach from
3772 standard IO until it is ready to receive connections on any of its devices.
3773 This option is a useful way for external programs to launch QEMU without having
3774 to cope with initialization race conditions.
3777 DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \
3778 "-option-rom rom load a file, rom, into the option ROM space\n",
3781 @item -option-rom @var{file}
3783 Load the contents of @var{file} as an option ROM.
3784 This option is useful to load things like EtherBoot.
3787 DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \
3788 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \
3789 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n",
3794 @item -rtc [base=utc|localtime|@var{datetime}][,clock=host|rt|vm][,driftfix=none|slew]
3796 Specify @option{base} as @code{utc} or @code{localtime} to let the RTC start at the current
3797 UTC or local time, respectively. @code{localtime} is required for correct date in
3798 MS-DOS or Windows. To start at a specific point in time, provide @var{datetime} in the
3799 format @code{2006-06-17T16:01:21} or @code{2006-06-17}. The default base is UTC.
3801 By default the RTC is driven by the host system time. This allows using of the
3802 RTC as accurate reference clock inside the guest, specifically if the host
3803 time is smoothly following an accurate external reference clock, e.g. via NTP.
3804 If you want to isolate the guest time from the host, you can set @option{clock}
3805 to @code{rt} instead, which provides a host monotonic clock if host support it.
3806 To even prevent the RTC from progressing during suspension, you can set @option{clock}
3807 to @code{vm} (virtual clock). @samp{clock=vm} is recommended especially in
3808 icount mode in order to preserve determinism; however, note that in icount mode
3809 the speed of the virtual clock is variable and can in general differ from the
3812 Enable @option{driftfix} (i386 targets only) if you experience time drift problems,
3813 specifically with Windows' ACPI HAL. This option will try to figure out how
3814 many timer interrupts were not processed by the Windows guest and will
3818 DEF("icount", HAS_ARG, QEMU_OPTION_icount, \
3819 "-icount [shift=N|auto][,align=on|off][,sleep=on|off,rr=record|replay,rrfile=<filename>,rrsnapshot=<snapshot>]\n" \
3820 " enable virtual instruction counter with 2^N clock ticks per\n" \
3821 " instruction, enable aligning the host and virtual clocks\n" \
3822 " or disable real time cpu sleeping\n", QEMU_ARCH_ALL)
3824 @item -icount [shift=@var{N}|auto][,rr=record|replay,rrfile=@var{filename},rrsnapshot=@var{snapshot}]
3826 Enable virtual instruction counter. The virtual cpu will execute one
3827 instruction every 2^@var{N} ns of virtual time. If @code{auto} is specified
3828 then the virtual cpu speed will be automatically adjusted to keep virtual
3829 time within a few seconds of real time.
3831 When the virtual cpu is sleeping, the virtual time will advance at default
3832 speed unless @option{sleep=on|off} is specified.
3833 With @option{sleep=on|off}, the virtual time will jump to the next timer deadline
3834 instantly whenever the virtual cpu goes to sleep mode and will not advance
3835 if no timer is enabled. This behavior give deterministic execution times from
3836 the guest point of view.
3838 Note that while this option can give deterministic behavior, it does not
3839 provide cycle accurate emulation. Modern CPUs contain superscalar out of
3840 order cores with complex cache hierarchies. The number of instructions
3841 executed often has little or no correlation with actual performance.
3843 @option{align=on} will activate the delay algorithm which will try
3844 to synchronise the host clock and the virtual clock. The goal is to
3845 have a guest running at the real frequency imposed by the shift option.
3846 Whenever the guest clock is behind the host clock and if
3847 @option{align=on} is specified then we print a message to the user
3848 to inform about the delay.
3849 Currently this option does not work when @option{shift} is @code{auto}.
3850 Note: The sync algorithm will work for those shift values for which
3851 the guest clock runs ahead of the host clock. Typically this happens
3852 when the shift value is high (how high depends on the host machine).
3854 When @option{rr} option is specified deterministic record/replay is enabled.
3855 Replay log is written into @var{filename} file in record mode and
3856 read from this file in replay mode.
3858 Option rrsnapshot is used to create new vm snapshot named @var{snapshot}
3859 at the start of execution recording. In replay mode this option is used
3860 to load the initial VM state.
3863 DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
3864 "-watchdog model\n" \
3865 " enable virtual hardware watchdog [default=none]\n",
3868 @item -watchdog @var{model}
3870 Create a virtual hardware watchdog device. Once enabled (by a guest
3871 action), the watchdog must be periodically polled by an agent inside
3872 the guest or else the guest will be restarted. Choose a model for
3873 which your guest has drivers.
3875 The @var{model} is the model of hardware watchdog to emulate. Use
3876 @code{-watchdog help} to list available hardware models. Only one
3877 watchdog can be enabled for a guest.
3879 The following models may be available:
3882 iBASE 700 is a very simple ISA watchdog with a single timer.
3884 Intel 6300ESB I/O controller hub is a much more featureful PCI-based
3885 dual-timer watchdog.
3887 A virtual watchdog for s390x backed by the diagnose 288 hypercall
3888 (currently KVM only).
3892 DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
3893 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
3894 " action when watchdog fires [default=reset]\n",
3897 @item -watchdog-action @var{action}
3898 @findex -watchdog-action
3900 The @var{action} controls what QEMU will do when the watchdog timer
3903 @code{reset} (forcefully reset the guest).
3904 Other possible actions are:
3905 @code{shutdown} (attempt to gracefully shutdown the guest),
3906 @code{poweroff} (forcefully poweroff the guest),
3907 @code{inject-nmi} (inject a NMI into the guest),
3908 @code{pause} (pause the guest),
3909 @code{debug} (print a debug message and continue), or
3910 @code{none} (do nothing).
3912 Note that the @code{shutdown} action requires that the guest responds
3913 to ACPI signals, which it may not be able to do in the sort of
3914 situations where the watchdog would have expired, and thus
3915 @code{-watchdog-action shutdown} is not recommended for production use.
3920 @item -watchdog i6300esb -watchdog-action pause
3921 @itemx -watchdog ib700
3925 DEF("echr", HAS_ARG, QEMU_OPTION_echr, \
3926 "-echr chr set terminal escape character instead of ctrl-a\n",
3930 @item -echr @var{numeric_ascii_value}
3932 Change the escape character used for switching to the monitor when using
3933 monitor and serial sharing. The default is @code{0x01} when using the
3934 @code{-nographic} option. @code{0x01} is equal to pressing
3935 @code{Control-a}. You can select a different character from the ascii
3936 control keys where 1 through 26 map to Control-a through Control-z. For
3937 instance you could use the either of the following to change the escape
3938 character to Control-t.
3945 DEF("show-cursor", 0, QEMU_OPTION_show_cursor, \
3946 "-show-cursor show cursor\n", QEMU_ARCH_ALL)
3949 @findex -show-cursor
3953 DEF("tb-size", HAS_ARG, QEMU_OPTION_tb_size, \
3954 "-tb-size n set TB size\n", QEMU_ARCH_ALL)
3956 @item -tb-size @var{n}
3958 Set TCG translation block cache size. Deprecated, use @samp{-accel tcg,tb-size=@var{n}}
3962 DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \
3963 "-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]\n" \
3964 "-incoming rdma:host:port[,ipv4][,ipv6]\n" \
3965 "-incoming unix:socketpath\n" \
3966 " prepare for incoming migration, listen on\n" \
3967 " specified protocol and socket address\n" \
3968 "-incoming fd:fd\n" \
3969 "-incoming exec:cmdline\n" \
3970 " accept incoming migration on given file descriptor\n" \
3971 " or from given external command\n" \
3972 "-incoming defer\n" \
3973 " wait for the URI to be specified via migrate_incoming\n",
3976 @item -incoming tcp:[@var{host}]:@var{port}[,to=@var{maxport}][,ipv4][,ipv6]
3977 @itemx -incoming rdma:@var{host}:@var{port}[,ipv4][,ipv6]
3979 Prepare for incoming migration, listen on a given tcp port.
3981 @item -incoming unix:@var{socketpath}
3982 Prepare for incoming migration, listen on a given unix socket.
3984 @item -incoming fd:@var{fd}
3985 Accept incoming migration from a given filedescriptor.
3987 @item -incoming exec:@var{cmdline}
3988 Accept incoming migration as an output from specified external command.
3990 @item -incoming defer
3991 Wait for the URI to be specified via migrate_incoming. The monitor can
3992 be used to change settings (such as migration parameters) prior to issuing
3993 the migrate_incoming to allow the migration to begin.
3996 DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \
3997 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL)
3999 @item -only-migratable
4000 @findex -only-migratable
4001 Only allow migratable devices. Devices will not be allowed to enter an
4005 DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
4006 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL)
4010 Don't create default devices. Normally, QEMU sets the default devices like serial
4011 port, parallel port, virtual console, monitor device, VGA adapter, floppy and
4012 CD-ROM drive and others. The @code{-nodefaults} option will disable all those
4017 DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
4018 "-chroot dir chroot to dir just before starting the VM\n",
4022 @item -chroot @var{dir}
4024 Immediately before starting guest execution, chroot to the specified
4025 directory. Especially useful in combination with -runas.
4029 DEF("runas", HAS_ARG, QEMU_OPTION_runas, \
4030 "-runas user change to user id user just before starting the VM\n" \
4031 " user can be numeric uid:gid instead\n",
4035 @item -runas @var{user}
4037 Immediately before starting guest execution, drop root privileges, switching
4038 to the specified user.
4041 DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env,
4042 "-prom-env variable=value\n"
4043 " set OpenBIOS nvram variables\n",
4044 QEMU_ARCH_PPC | QEMU_ARCH_SPARC)
4046 @item -prom-env @var{variable}=@var{value}
4048 Set OpenBIOS nvram @var{variable} to given @var{value} (PPC, SPARC only).
4050 DEF("semihosting", 0, QEMU_OPTION_semihosting,
4051 "-semihosting semihosting mode\n",
4052 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4053 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
4056 @findex -semihosting
4057 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only).
4059 DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
4060 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
4061 " semihosting configuration\n",
4062 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4063 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2)
4065 @item -semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]
4066 @findex -semihosting-config
4067 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II only).
4069 @item target=@code{native|gdb|auto}
4070 Defines where the semihosting calls will be addressed, to QEMU (@code{native})
4071 or to GDB (@code{gdb}). The default is @code{auto}, which means @code{gdb}
4072 during debug sessions and @code{native} otherwise.
4073 @item chardev=@var{str1}
4074 Send the output to a chardev backend output for native or auto output when not in gdb
4075 @item arg=@var{str1},arg=@var{str2},...
4076 Allows the user to pass input arguments, and can be used multiple times to build
4077 up a list. The old-style @code{-kernel}/@code{-append} method of passing a
4078 command line is still supported for backward compatibility. If both the
4079 @code{--semihosting-config arg} and the @code{-kernel}/@code{-append} are
4080 specified, the former is passed to semihosting as it always takes precedence.
4083 DEF("old-param", 0, QEMU_OPTION_old_param,
4084 "-old-param old param mode\n", QEMU_ARCH_ARM)
4087 @findex -old-param (ARM)
4088 Old param mode (ARM only).
4091 DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
4092 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4093 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4094 " Enable seccomp mode 2 system call filter (default 'off').\n" \
4095 " use 'obsolete' to allow obsolete system calls that are provided\n" \
4096 " by the kernel, but typically no longer used by modern\n" \
4097 " C library implementations.\n" \
4098 " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
4099 " its privileges by blacklisting all set*uid|gid system calls.\n" \
4100 " The value 'children' will deny set*uid|gid system calls for\n" \
4101 " main QEMU process but will allow forks and execves to run unprivileged\n" \
4102 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4103 " blacklisting *fork and execve\n" \
4104 " use 'resourcecontrol' to disable process affinity and schedular priority\n",
4107 @item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}][,resourcecontrol=@var{string}]
4109 Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
4110 disable it. The default is 'off'.
4112 @item obsolete=@var{string}
4113 Enable Obsolete system calls
4114 @item elevateprivileges=@var{string}
4115 Disable set*uid|gid system calls
4116 @item spawn=@var{string}
4117 Disable *fork and execve
4118 @item resourcecontrol=@var{string}
4119 Disable process affinity and schedular priority
4123 DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
4124 "-readconfig <file>\n", QEMU_ARCH_ALL)
4126 @item -readconfig @var{file}
4128 Read device configuration from @var{file}. This approach is useful when you want to spawn
4129 QEMU process with many command line options but you don't want to exceed the command line
4132 DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
4133 "-writeconfig <file>\n"
4134 " read/write config file\n", QEMU_ARCH_ALL)
4136 @item -writeconfig @var{file}
4137 @findex -writeconfig
4138 Write device configuration to @var{file}. The @var{file} can be either filename to save
4139 command line and device configuration into file or dash @code{-}) character to print the
4140 output to stdout. This can be later used as input file for @code{-readconfig} option.
4143 DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4145 " do not load default user-provided config files at startup\n",
4148 @item -no-user-config
4149 @findex -no-user-config
4150 The @code{-no-user-config} option makes QEMU not load any of the user-provided
4151 config files on @var{sysconfdir}.
4154 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4155 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4156 " specify tracing options\n",
4159 HXCOMM This line is not accurate, as some sub-options are backend-specific but
4160 HXCOMM HX does not support conditional compilation of text.
4161 @item -trace [[enable=]@var{pattern}][,events=@var{file}][,file=@var{file}]
4163 @include qemu-option-trace.texi
4165 DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4166 "-plugin [file=]<file>[,arg=<string>]\n"
4170 @item -plugin file=@var{file}[,arg=@var{string}]
4176 @item file=@var{file}
4177 Load the given plugin from a shared library file.
4178 @item arg=@var{string}
4179 Argument string passed to the plugin. (Can be given multiple times.)
4184 DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4185 DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4188 DEF("enable-fips", 0, QEMU_OPTION_enablefips,
4189 "-enable-fips enable FIPS 140-2 compliance\n",
4194 @findex -enable-fips
4195 Enable FIPS 140-2 compliance mode.
4198 HXCOMM Deprecated by -accel tcg
4199 DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386)
4201 DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4202 "-msg timestamp[=on|off]\n"
4203 " control error message format\n"
4204 " timestamp=on enables timestamps (default: off)\n",
4207 @item -msg timestamp[=on|off]
4209 Control error message format.
4211 @item timestamp=on|off
4212 Prefix messages with a timestamp. Default is off.
4216 DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
4217 "-dump-vmstate <file>\n"
4218 " Output vmstate information in JSON format to file.\n"
4219 " Use the scripts/vmstate-static-checker.py file to\n"
4220 " check for possible regressions in migration code\n"
4221 " by comparing two such vmstate dumps.\n",
4224 @item -dump-vmstate @var{file}
4225 @findex -dump-vmstate
4226 Dump json-encoded vmstate information for current machine type to file
4230 DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
4231 "-enable-sync-profile\n"
4232 " enable synchronization profiling\n",
4235 @item -enable-sync-profile
4236 @findex -enable-sync-profile
4237 Enable synchronization profiling.
4245 DEFHEADING(Generic object creation:)
4250 DEF("object", HAS_ARG, QEMU_OPTION_object,
4251 "-object TYPENAME[,PROP1=VALUE1,...]\n"
4252 " create a new object of type TYPENAME setting properties\n"
4253 " in the order they are specified. Note that the 'id'\n"
4254 " property must be set. These objects are placed in the\n"
4255 " '/objects' path.\n",
4258 @item -object @var{typename}[,@var{prop1}=@var{value1},...]
4260 Create a new object of type @var{typename} setting properties
4261 in the order they are specified. Note that the 'id'
4262 property must be set. These objects are placed in the
4267 @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}
4269 Creates a memory file backend object, which can be used to back
4270 the guest RAM with huge pages.
4272 The @option{id} parameter is a unique ID that will be used to reference this
4273 memory region when configuring the @option{-numa} argument.
4275 The @option{size} option provides the size of the memory region, and accepts
4276 common suffixes, eg @option{500M}.
4278 The @option{mem-path} provides the path to either a shared memory or huge page
4281 The @option{share} boolean option determines whether the memory
4282 region is marked as private to QEMU, or shared. The latter allows
4283 a co-operating external process to access the QEMU memory region.
4285 The @option{share} is also required for pvrdma devices due to
4286 limitations in the RDMA API provided by Linux.
4288 Setting share=on might affect the ability to configure NUMA
4289 bindings for the memory backend under some circumstances, see
4290 Documentation/vm/numa_memory_policy.txt on the Linux kernel
4291 source tree for additional details.
4293 Setting the @option{discard-data} boolean option to @var{on}
4294 indicates that file contents can be destroyed when QEMU exits,
4295 to avoid unnecessarily flushing data to the backing file. Note
4296 that @option{discard-data} is only an optimization, and QEMU
4297 might not discard file contents if it aborts unexpectedly or is
4298 terminated using SIGKILL.
4300 The @option{merge} boolean option enables memory merge, also known as
4301 MADV_MERGEABLE, so that Kernel Samepage Merging will consider the pages for
4302 memory deduplication.
4304 Setting the @option{dump} boolean option to @var{off} excludes the memory from
4305 core dumps. This feature is also known as MADV_DONTDUMP.
4307 The @option{prealloc} boolean option enables memory preallocation.
4309 The @option{host-nodes} option binds the memory range to a list of NUMA host
4312 The @option{policy} option sets the NUMA policy to one of the following values:
4318 @item @var{preferred}
4319 prefer the given host node list for allocation
4322 restrict memory allocation to the given host node list
4324 @item @var{interleave}
4325 interleave memory allocations across the given host node list
4328 The @option{align} option specifies the base address alignment when
4329 QEMU mmap(2) @option{mem-path}, and accepts common suffixes, eg
4330 @option{2M}. Some backend store specified by @option{mem-path}
4331 requires an alignment different than the default one used by QEMU, eg
4332 the device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
4333 such cases, users can specify the required alignment via this option.
4335 The @option{pmem} option specifies whether the backing file specified
4336 by @option{mem-path} is in host persistent memory that can be accessed
4337 using the SNIA NVM programming model (e.g. Intel NVDIMM).
4338 If @option{pmem} is set to 'on', QEMU will take necessary operations to
4339 guarantee the persistence of its own writes to @option{mem-path}
4340 (e.g. in vNVDIMM label emulation and live migration).
4341 Also, we will map the backend-file with MAP_SYNC flag, which ensures the
4342 file metadata is in sync for @option{mem-path} in case of host crash
4343 or a power failure. MAP_SYNC requires support from both the host kernel
4344 (since Linux kernel 4.15) and the filesystem of @option{mem-path} mounted
4347 @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}
4349 Creates a memory backend object, which can be used to back the guest RAM.
4350 Memory backend objects offer more control than the @option{-m} option that is
4351 traditionally used to define guest RAM. Please refer to
4352 @option{memory-backend-file} for a description of the options.
4354 @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}
4356 Creates an anonymous memory file backend object, which allows QEMU to
4357 share the memory with an external process (e.g. when using
4358 vhost-user). The memory is allocated with memfd and optional
4359 sealing. (Linux only)
4361 The @option{seal} option creates a sealed-file, that will block
4362 further resizing the memory ('on' by default).
4364 The @option{hugetlb} option specify the file to be created resides in
4365 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction with
4366 the @option{hugetlb} option, the @option{hugetlbsize} option specify
4367 the hugetlb page size on systems that support multiple hugetlb page
4368 sizes (it must be a power of 2 value supported by the system).
4370 In some versions of Linux, the @option{hugetlb} option is incompatible
4371 with the @option{seal} option (requires at least Linux 4.16).
4373 Please refer to @option{memory-backend-file} for a description of the
4376 The @option{share} boolean option is @var{on} by default with memfd.
4378 @item -object rng-builtin,id=@var{id}
4380 Creates a random number generator backend which obtains entropy from
4381 QEMU builtin functions. The @option{id} parameter is a unique ID that
4382 will be used to reference this entropy backend from the @option{virtio-rng}
4383 device. By default, the @option{virtio-rng} device uses this RNG backend.
4385 @item -object rng-random,id=@var{id},filename=@var{/dev/random}
4387 Creates a random number generator backend which obtains entropy from
4388 a device on the host. The @option{id} parameter is a unique ID that
4389 will be used to reference this entropy backend from the @option{virtio-rng}
4390 device. The @option{filename} parameter specifies which file to obtain
4391 entropy from and if omitted defaults to @option{/dev/urandom}.
4393 @item -object rng-egd,id=@var{id},chardev=@var{chardevid}
4395 Creates a random number generator backend which obtains entropy from
4396 an external daemon running on the host. The @option{id} parameter is
4397 a unique ID that will be used to reference this entropy backend from
4398 the @option{virtio-rng} device. The @option{chardev} parameter is
4399 the unique ID of a character device backend that provides the connection
4402 @item -object tls-creds-anon,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/cred/dir},verify-peer=@var{on|off}
4404 Creates a TLS anonymous credentials object, which can be used to provide
4405 TLS support on network backends. The @option{id} parameter is a unique
4406 ID which network backends will use to access the credentials. The
4407 @option{endpoint} is either @option{server} or @option{client} depending
4408 on whether the QEMU network backend that uses the credentials will be
4409 acting as a client or as a server. If @option{verify-peer} is enabled
4410 (the default) then once the handshake is completed, the peer credentials
4411 will be verified, though this is a no-op for anonymous credentials.
4413 The @var{dir} parameter tells QEMU where to find the credential
4414 files. For server endpoints, this directory may contain a file
4415 @var{dh-params.pem} providing diffie-hellman parameters to use
4416 for the TLS server. If the file is missing, QEMU will generate
4417 a set of DH parameters at startup. This is a computationally
4418 expensive operation that consumes random pool entropy, so it is
4419 recommended that a persistent set of parameters be generated
4422 @item -object tls-creds-psk,id=@var{id},endpoint=@var{endpoint},dir=@var{/path/to/keys/dir}[,username=@var{username}]
4424 Creates a TLS Pre-Shared Keys (PSK) credentials object, which can be used to provide
4425 TLS support on network backends. The @option{id} parameter is a unique
4426 ID which network backends will use to access the credentials. The
4427 @option{endpoint} is either @option{server} or @option{client} depending
4428 on whether the QEMU network backend that uses the credentials will be
4429 acting as a client or as a server. For clients only, @option{username}
4430 is the username which will be sent to the server. If omitted
4431 it defaults to ``qemu''.
4433 The @var{dir} parameter tells QEMU where to find the keys file.
4434 It is called ``@var{dir}/keys.psk'' and contains ``username:key''
4435 pairs. This file can most easily be created using the GnuTLS
4436 @code{psktool} program.
4438 For server endpoints, @var{dir} may also contain a file
4439 @var{dh-params.pem} providing diffie-hellman parameters to use
4440 for the TLS server. If the file is missing, QEMU will generate
4441 a set of DH parameters at startup. This is a computationally
4442 expensive operation that consumes random pool entropy, so it is
4443 recommended that a persistent set of parameters be generated
4446 @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}
4448 Creates a TLS anonymous credentials object, which can be used to provide
4449 TLS support on network backends. The @option{id} parameter is a unique
4450 ID which network backends will use to access the credentials. The
4451 @option{endpoint} is either @option{server} or @option{client} depending
4452 on whether the QEMU network backend that uses the credentials will be
4453 acting as a client or as a server. If @option{verify-peer} is enabled
4454 (the default) then once the handshake is completed, the peer credentials
4455 will be verified. With x509 certificates, this implies that the clients
4456 must be provided with valid client certificates too.
4458 The @var{dir} parameter tells QEMU where to find the credential
4459 files. For server endpoints, this directory may contain a file
4460 @var{dh-params.pem} providing diffie-hellman parameters to use
4461 for the TLS server. If the file is missing, QEMU will generate
4462 a set of DH parameters at startup. This is a computationally
4463 expensive operation that consumes random pool entropy, so it is
4464 recommended that a persistent set of parameters be generated
4467 For x509 certificate credentials the directory will contain further files
4468 providing the x509 certificates. The certificates must be stored
4469 in PEM format, in filenames @var{ca-cert.pem}, @var{ca-crl.pem} (optional),
4470 @var{server-cert.pem} (only servers), @var{server-key.pem} (only servers),
4471 @var{client-cert.pem} (only clients), and @var{client-key.pem} (only clients).
4473 For the @var{server-key.pem} and @var{client-key.pem} files which
4474 contain sensitive private keys, it is possible to use an encrypted
4475 version by providing the @var{passwordid} parameter. This provides
4476 the ID of a previously created @code{secret} object containing the
4477 password for decryption.
4479 The @var{priority} parameter allows to override the global default
4480 priority used by gnutls. This can be useful if the system administrator
4481 needs to use a weaker set of crypto priorities for QEMU without
4482 potentially forcing the weakness onto all applications. Or conversely
4483 if one wants wants a stronger default for QEMU than for all other
4484 applications, they can do this through this parameter. Its format is
4485 a gnutls priority string as described at
4486 @url{https://gnutls.org/manual/html_node/Priority-Strings.html}.
4488 @item -object filter-buffer,id=@var{id},netdev=@var{netdevid},interval=@var{t}[,queue=@var{all|rx|tx}][,status=@var{on|off}]
4490 Interval @var{t} can't be 0, this filter batches the packet delivery: all
4491 packets arriving in a given interval on netdev @var{netdevid} are delayed
4492 until the end of the interval. Interval is in microseconds.
4493 @option{status} is optional that indicate whether the netfilter is
4494 on (enabled) or off (disabled), the default status for netfilter will be 'on'.
4496 queue @var{all|rx|tx} is an option that can be applied to any netfilter.
4498 @option{all}: the filter is attached both to the receive and the transmit
4499 queue of the netdev (default).
4501 @option{rx}: the filter is attached to the receive queue of the netdev,
4502 where it will receive packets sent to the netdev.
4504 @option{tx}: the filter is attached to the transmit queue of the netdev,
4505 where it will receive packets sent by the netdev.
4507 @item -object filter-mirror,id=@var{id},netdev=@var{netdevid},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support]
4509 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.
4511 @item -object filter-redirector,id=@var{id},netdev=@var{netdevid},indev=@var{chardevid},outdev=@var{chardevid},queue=@var{all|rx|tx}[,vnet_hdr_support]
4513 filter-redirector on netdev @var{netdevid},redirect filter's net packet to chardev
4514 @var{chardevid},and redirect indev's packet to filter.if it has the vnet_hdr_support flag,
4515 filter-redirector will redirect packet with vnet_hdr_len.
4516 Create a filter-redirector we need to differ outdev id from indev id, id can not
4517 be the same. we can just use indev or outdev, but at least one of indev or outdev
4518 need to be specified.
4520 @item -object filter-rewriter,id=@var{id},netdev=@var{netdevid},queue=@var{all|rx|tx},[vnet_hdr_support]
4522 Filter-rewriter is a part of COLO project.It will rewrite tcp packet to
4523 secondary from primary to keep secondary tcp connection,and rewrite
4524 tcp packet to primary from secondary make tcp packet can be handled by
4525 client.if it has the vnet_hdr_support flag, we can parse packet with vnet header.
4529 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4530 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4531 -object filter-rewriter,id=rew0,netdev=hn0,queue=all
4533 @item -object filter-dump,id=@var{id},netdev=@var{dev}[,file=@var{filename}][,maxlen=@var{len}]
4535 Dump the network traffic on netdev @var{dev} to the file specified by
4536 @var{filename}. At most @var{len} bytes (64k by default) per packet are stored.
4537 The file format is libpcap, so it can be analyzed with tools such as tcpdump
4540 @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}]
4542 Colo-compare gets packet from primary_in@var{chardevid} and secondary_in@var{chardevid}, than compare primary packet with
4543 secondary packet. If the packets are same, we will output primary
4544 packet to outdev@var{chardevid}, else we will notify colo-frame
4545 do checkpoint and send primary packet to outdev@var{chardevid}.
4546 In order to improve efficiency, we need to put the task of comparison
4547 in another thread. If it has the vnet_hdr_support flag, colo compare
4548 will send/recv packet with vnet_hdr_len.
4549 If you want to use Xen COLO, will need the notify_dev to notify Xen
4550 colo-frame to do checkpoint.
4552 we must use it with the help of filter-mirror and filter-redirector.
4559 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4560 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4561 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4562 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4563 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4564 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4565 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4566 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4567 -object iothread,id=iothread1
4568 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4569 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4570 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4571 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1
4574 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4575 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4576 -chardev socket,id=red0,host=3.3.3.3,port=9003
4577 -chardev socket,id=red1,host=3.3.3.3,port=9004
4578 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4579 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4585 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown
4586 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66
4587 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait
4588 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait
4589 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait
4590 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001
4591 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait
4592 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005
4593 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait
4594 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0
4595 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out
4596 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0
4597 -object iothread,id=iothread1
4598 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1
4601 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown
4602 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66
4603 -chardev socket,id=red0,host=3.3.3.3,port=9003
4604 -chardev socket,id=red1,host=3.3.3.3,port=9004
4605 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0
4606 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1
4610 If you want to know the detail of above command line, you can read
4611 the colo-compare git log.
4613 @item -object cryptodev-backend-builtin,id=@var{id}[,queues=@var{queues}]
4615 Creates a cryptodev backend which executes crypto opreation from
4616 the QEMU cipher APIS. The @var{id} parameter is
4617 a unique ID that will be used to reference this cryptodev backend from
4618 the @option{virtio-crypto} device. The @var{queues} parameter is optional,
4619 which specify the queue number of cryptodev backend, the default of
4624 # @value{qemu_system} \
4626 -object cryptodev-backend-builtin,id=cryptodev0 \
4627 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
4631 @item -object cryptodev-vhost-user,id=@var{id},chardev=@var{chardevid}[,queues=@var{queues}]
4633 Creates a vhost-user cryptodev backend, backed by a chardev @var{chardevid}.
4634 The @var{id} parameter is a unique ID that will be used to reference this
4635 cryptodev backend from the @option{virtio-crypto} device.
4636 The chardev should be a unix domain socket backed one. The vhost-user uses
4637 a specifically defined protocol to pass vhost ioctl replacement messages
4638 to an application on the other end of the socket.
4639 The @var{queues} parameter is optional, which specify the queue number
4640 of cryptodev backend for multiqueue vhost-user, the default of @var{queues} is 1.
4644 # @value{qemu_system} \
4646 -chardev socket,id=chardev0,path=/path/to/socket \
4647 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \
4648 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \
4652 @item -object secret,id=@var{id},data=@var{string},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]
4653 @item -object secret,id=@var{id},file=@var{filename},format=@var{raw|base64}[,keyid=@var{secretid},iv=@var{string}]
4655 Defines a secret to store a password, encryption key, or some other sensitive
4656 data. The sensitive data can either be passed directly via the @var{data}
4657 parameter, or indirectly via the @var{file} parameter. Using the @var{data}
4658 parameter is insecure unless the sensitive data is encrypted.
4660 The sensitive data can be provided in raw format (the default), or base64.
4661 When encoded as JSON, the raw format only supports valid UTF-8 characters,
4662 so base64 is recommended for sending binary data. QEMU will convert from
4663 which ever format is provided to the format it needs internally. eg, an
4664 RBD password can be provided in raw format, even though it will be base64
4665 encoded when passed onto the RBD sever.
4667 For added protection, it is possible to encrypt the data associated with
4668 a secret using the AES-256-CBC cipher. Use of encryption is indicated
4669 by providing the @var{keyid} and @var{iv} parameters. The @var{keyid}
4670 parameter provides the ID of a previously defined secret that contains
4671 the AES-256 decryption key. This key should be 32-bytes long and be
4672 base64 encoded. The @var{iv} parameter provides the random initialization
4673 vector used for encryption of this particular secret and should be a
4674 base64 encrypted string of the 16-byte IV.
4676 The simplest (insecure) usage is to provide the secret inline
4680 # @value{qemu_system} -object secret,id=sec0,data=letmein,format=raw
4684 The simplest secure usage is to provide the secret via a file
4686 # printf "letmein" > mypasswd.txt
4687 # @value{qemu_system} -object secret,id=sec0,file=mypasswd.txt,format=raw
4689 For greater security, AES-256-CBC should be used. To illustrate usage,
4690 consider the openssl command line tool which can encrypt the data. Note
4691 that when encrypting, the plaintext must be padded to the cipher block
4692 size (32 bytes) using the standard PKCS#5/6 compatible padding algorithm.
4694 First a master key needs to be created in base64 encoding:
4697 # openssl rand -base64 32 > key.b64
4698 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"')
4701 Each secret to be encrypted needs to have a random initialization vector
4702 generated. These do not need to be kept secret
4705 # openssl rand -base64 16 > iv.b64
4706 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"')
4709 The secret to be defined can now be encrypted, in this case we're
4710 telling openssl to base64 encode the result, but it could be left
4711 as raw bytes if desired.
4714 # SECRET=$(printf "letmein" |
4715 openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
4718 When launching QEMU, create a master secret pointing to @code{key.b64}
4719 and specify that to be used to decrypt the user password. Pass the
4720 contents of @code{iv.b64} to the second secret
4723 # @value{qemu_system} \
4724 -object secret,id=secmaster0,format=base64,file=key.b64 \
4725 -object secret,id=sec0,keyid=secmaster0,format=base64,\
4726 data=$SECRET,iv=$(<iv.b64)
4729 @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}]
4731 Create a Secure Encrypted Virtualization (SEV) guest object, which can be used
4732 to provide the guest memory encryption support on AMD processors.
4734 When memory encryption is enabled, one of the physical address bit (aka the
4735 C-bit) is utilized to mark if a memory page is protected. The @option{cbitpos}
4736 is used to provide the C-bit position. The C-bit position is Host family dependent
4737 hence user must provide this value. On EPYC, the value should be 47.
4739 When memory encryption is enabled, we loose certain bits in physical address space.
4740 The @option{reduced-phys-bits} is used to provide the number of bits we loose in
4741 physical address space. Similar to C-bit, the value is Host family dependent.
4742 On EPYC, the value should be 5.
4744 The @option{sev-device} provides the device file to use for communicating with
4745 the SEV firmware running inside AMD Secure Processor. The default device is
4746 '/dev/sev'. If hardware supports memory encryption then /dev/sev devices are
4747 created by CCP driver.
4749 The @option{policy} provides the guest policy to be enforced by the SEV firmware
4750 and restrict what configuration and operational commands can be performed on this
4751 guest by the hypervisor. The policy should be provided by the guest owner and is
4752 bound to the guest and cannot be changed throughout the lifetime of the guest.
4755 If guest @option{policy} allows sharing the key with another SEV guest then
4756 @option{handle} can be use to provide handle of the guest from which to share
4759 The @option{dh-cert-file} and @option{session-file} provides the guest owner's
4760 Public Diffie-Hillman key defined in SEV spec. The PDH and session parameters
4761 are used for establishing a cryptographic session with the guest owner to
4762 negotiate keys used for attestation. The file must be encoded in base64.
4764 e.g to launch a SEV guest
4766 # @value{qemu_system_x86} \
4768 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \
4769 -machine ...,memory-encryption=sev0
4775 @item -object authz-simple,id=@var{id},identity=@var{string}
4777 Create an authorization object that will control access to network services.
4779 The @option{identity} parameter is identifies the user and its format
4780 depends on the network service that authorization object is associated
4781 with. For authorizing based on TLS x509 certificates, the identity must
4782 be the x509 distinguished name. Note that care must be taken to escape
4783 any commas in the distinguished name.
4785 An example authorization object to validate a x509 distinguished name
4788 # @value{qemu_system} \
4790 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \
4794 Note the use of quotes due to the x509 distinguished name containing
4795 whitespace, and escaping of ','.
4797 @item -object authz-listfile,id=@var{id},filename=@var{path},refresh=@var{yes|no}
4799 Create an authorization object that will control access to network services.
4801 The @option{filename} parameter is the fully qualified path to a file
4802 containing the access control list rules in JSON format.
4804 An example set of rules that match against SASL usernames might look
4810 @{ "match": "fred", "policy": "allow", "format": "exact" @},
4811 @{ "match": "bob", "policy": "allow", "format": "exact" @},
4812 @{ "match": "danb", "policy": "deny", "format": "glob" @},
4813 @{ "match": "dan*", "policy": "allow", "format": "exact" @},
4819 When checking access the object will iterate over all the rules and
4820 the first rule to match will have its @option{policy} value returned
4821 as the result. If no rules match, then the default @option{policy}
4824 The rules can either be an exact string match, or they can use the
4825 simple UNIX glob pattern matching to allow wildcards to be used.
4827 If @option{refresh} is set to true the file will be monitored
4828 and automatically reloaded whenever its content changes.
4830 As with the @code{authz-simple} object, the format of the identity
4831 strings being matched depends on the network service, but is usually
4832 a TLS x509 distinguished name, or a SASL username.
4834 An example authorization object to validate a SASL username
4837 # @value{qemu_system} \
4839 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=yes
4843 @item -object authz-pam,id=@var{id},service=@var{string}
4845 Create an authorization object that will control access to network services.
4847 The @option{service} parameter provides the name of a PAM service to use
4848 for authorization. It requires that a file @code{/etc/pam.d/@var{service}}
4849 exist to provide the configuration for the @code{account} subsystem.
4851 An example authorization object to validate a TLS x509 distinguished
4852 name would look like:
4855 # @value{qemu_system} \
4857 -object authz-pam,id=auth0,service=qemu-vnc
4861 There would then be a corresponding config file for PAM at
4862 @code{/etc/pam.d/qemu-vnc} that contains:
4865 account requisite pam_listfile.so item=user sense=allow \
4866 file=/etc/qemu/vnc.allow
4869 Finally the @code{/etc/qemu/vnc.allow} file would contain
4870 the list of x509 distingished names that are permitted
4874 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB
4877 @item -object iothread,id=@var{id},poll-max-ns=@var{poll-max-ns},poll-grow=@var{poll-grow},poll-shrink=@var{poll-shrink}
4879 Creates a dedicated event loop thread that devices can be assigned to. This is
4880 known as an IOThread. By default device emulation happens in vCPU threads or
4881 the main event loop thread. This can become a scalability bottleneck.
4882 IOThreads allow device emulation and I/O to run on other host CPUs.
4884 The @option{id} parameter is a unique ID that will be used to reference this
4885 IOThread from @option{-device ...,iothread=@var{id}}. Multiple devices can be
4886 assigned to an IOThread. Note that not all devices support an
4887 @option{iothread} parameter.
4889 The @code{query-iothreads} QMP command lists IOThreads and reports their thread
4890 IDs so that the user can configure host CPU pinning/affinity.
4892 IOThreads use an adaptive polling algorithm to reduce event loop latency.
4893 Instead of entering a blocking system call to monitor file descriptors and then
4894 pay the cost of being woken up when an event occurs, the polling algorithm
4895 spins waiting for events for a short time. The algorithm's default parameters
4896 are suitable for many cases but can be adjusted based on knowledge of the
4897 workload and/or host device latency.
4899 The @option{poll-max-ns} parameter is the maximum number of nanoseconds to busy
4900 wait for events. Polling can be disabled by setting this value to 0.
4902 The @option{poll-grow} parameter is the multiplier used to increase the polling
4903 time when the algorithm detects it is missing events due to not polling long
4906 The @option{poll-shrink} parameter is the divisor used to decrease the polling
4907 time when the algorithm detects it is spending too long polling without
4908 encountering events.
4910 The polling parameters can be modified at run-time using the @code{qom-set} command (where @code{iothread1} is the IOThread's @code{id}):
4913 (qemu) qom-set /objects/iothread1 poll-max-ns 100000
4921 HXCOMM This is the last statement. Insert new options before this line!