1HXCOMM Use DEFHEADING() to define headings in both help text and rST. 2HXCOMM Text between SRST and ERST is copied to the rST version and 3HXCOMM discarded from C version. 4HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to 5HXCOMM construct option structures, enums and help message for specified 6HXCOMM architectures. 7HXCOMM HXCOMM can be used for comments, discarded from both rST and C. 8 9DEFHEADING(Standard options:) 10 11DEF("help", 0, QEMU_OPTION_h, 12 "-h or -help display this help and exit\n", QEMU_ARCH_ALL) 13SRST 14``-h`` 15 Display help and exit 16ERST 17 18DEF("version", 0, QEMU_OPTION_version, 19 "-version display version information and exit\n", QEMU_ARCH_ALL) 20SRST 21``-version`` 22 Display version information and exit 23ERST 24 25DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ 26 "-machine [type=]name[,prop[=value][,...]]\n" 27 " selects emulated machine ('-machine help' for list)\n" 28 " property accel=accel1[:accel2[:...]] selects accelerator\n" 29 " supported accelerators are kvm, xen, hax, hvf, whpx or tcg (default: tcg)\n" 30 " vmport=on|off|auto controls emulation of vmport (default: auto)\n" 31 " dump-guest-core=on|off include guest memory in a core dump (default=on)\n" 32 " mem-merge=on|off controls memory merge support (default: on)\n" 33 " aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n" 34 " dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n" 35 " suppress-vmdesc=on|off disables self-describing migration (default=off)\n" 36 " nvdimm=on|off controls NVDIMM support (default=off)\n" 37 " enforce-config-section=on|off enforce configuration section migration (default=off)\n" 38 " memory-encryption=@var{} memory encryption object to use (default=none)\n" 39 " hmat=on|off controls ACPI HMAT support (default=off)\n", 40 QEMU_ARCH_ALL) 41SRST 42``-machine [type=]name[,prop=value[,...]]`` 43 Select the emulated machine by name. Use ``-machine help`` to list 44 available machines. 45 46 For architectures which aim to support live migration compatibility 47 across releases, each release will introduce a new versioned machine 48 type. For example, the 2.8.0 release introduced machine types 49 "pc-i440fx-2.8" and "pc-q35-2.8" for the x86\_64/i686 architectures. 50 51 To allow live migration of guests from QEMU version 2.8.0, to QEMU 52 version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8" 53 and "pc-q35-2.8" machines too. To allow users live migrating VMs to 54 skip multiple intermediate releases when upgrading, new releases of 55 QEMU will support machine types from many previous versions. 56 57 Supported machine properties are: 58 59 ``accel=accels1[:accels2[:...]]`` 60 This is used to enable an accelerator. Depending on the target 61 architecture, kvm, xen, hax, hvf, whpx or tcg can be available. 62 By default, tcg is used. If there is more than one accelerator 63 specified, the next one is used if the previous one fails to 64 initialize. 65 66 ``vmport=on|off|auto`` 67 Enables emulation of VMWare IO port, for vmmouse etc. auto says 68 to select the value based on accel. For accel=xen the default is 69 off otherwise the default is on. 70 71 ``dump-guest-core=on|off`` 72 Include guest memory in a core dump. The default is on. 73 74 ``mem-merge=on|off`` 75 Enables or disables memory merge support. This feature, when 76 supported by the host, de-duplicates identical memory pages 77 among VMs instances (enabled by default). 78 79 ``aes-key-wrap=on|off`` 80 Enables or disables AES key wrapping support on s390-ccw hosts. 81 This feature controls whether AES wrapping keys will be created 82 to allow execution of AES cryptographic functions. The default 83 is on. 84 85 ``dea-key-wrap=on|off`` 86 Enables or disables DEA key wrapping support on s390-ccw hosts. 87 This feature controls whether DEA wrapping keys will be created 88 to allow execution of DEA cryptographic functions. The default 89 is on. 90 91 ``nvdimm=on|off`` 92 Enables or disables NVDIMM support. The default is off. 93 94 ``enforce-config-section=on|off`` 95 If ``enforce-config-section`` is set to on, force migration code 96 to send configuration section even if the machine-type sets the 97 ``migration.send-configuration`` property to off. NOTE: this 98 parameter is deprecated. Please use ``-global`` 99 ``migration.send-configuration``\ =on\|off instead. 100 101 ``memory-encryption=`` 102 Memory encryption object to use. The default is none. 103 104 ``hmat=on|off`` 105 Enables or disables ACPI Heterogeneous Memory Attribute Table 106 (HMAT) support. The default is off. 107ERST 108 109HXCOMM Deprecated by -machine 110DEF("M", HAS_ARG, QEMU_OPTION_M, "", QEMU_ARCH_ALL) 111 112DEF("cpu", HAS_ARG, QEMU_OPTION_cpu, 113 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL) 114SRST 115``-cpu model`` 116 Select CPU model (``-cpu help`` for list and additional feature 117 selection) 118ERST 119 120DEF("accel", HAS_ARG, QEMU_OPTION_accel, 121 "-accel [accel=]accelerator[,prop[=value][,...]]\n" 122 " select accelerator (kvm, xen, hax, hvf, whpx or tcg; use 'help' for a list)\n" 123 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n" 124 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n" 125 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n" 126 " tb-size=n (TCG translation block cache size)\n" 127 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL) 128SRST 129``-accel name[,prop=value[,...]]`` 130 This is used to enable an accelerator. Depending on the target 131 architecture, kvm, xen, hax, hvf, whpx or tcg can be available. By 132 default, tcg is used. If there is more than one accelerator 133 specified, the next one is used if the previous one fails to 134 initialize. 135 136 ``igd-passthru=on|off`` 137 When Xen is in use, this option controls whether Intel 138 integrated graphics devices can be passed through to the guest 139 (default=off) 140 141 ``kernel-irqchip=on|off|split`` 142 Controls KVM in-kernel irqchip support. The default is full 143 acceleration of the interrupt controllers. On x86, split irqchip 144 reduces the kernel attack surface, at a performance cost for 145 non-MSI interrupts. Disabling the in-kernel irqchip completely 146 is not recommended except for debugging purposes. 147 148 ``kvm-shadow-mem=size`` 149 Defines the size of the KVM shadow MMU. 150 151 ``tb-size=n`` 152 Controls the size (in MiB) of the TCG translation block cache. 153 154 ``thread=single|multi`` 155 Controls number of TCG threads. When the TCG is multi-threaded 156 there will be one thread per vCPU therefor taking advantage of 157 additional host cores. The default is to enable multi-threading 158 where both the back-end and front-ends support it and no 159 incompatible TCG features have been enabled (e.g. 160 icount/replay). 161ERST 162 163DEF("smp", HAS_ARG, QEMU_OPTION_smp, 164 "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n" 165 " set the number of CPUs to 'n' [default=1]\n" 166 " maxcpus= maximum number of total cpus, including\n" 167 " offline CPUs for hotplug, etc\n" 168 " cores= number of CPU cores on one socket (for PC, it's on one die)\n" 169 " threads= number of threads on one CPU core\n" 170 " dies= number of CPU dies on one socket (for PC only)\n" 171 " sockets= number of discrete sockets in the system\n", 172 QEMU_ARCH_ALL) 173SRST 174``-smp [cpus=]n[,cores=cores][,threads=threads][,dies=dies][,sockets=sockets][,maxcpus=maxcpus]`` 175 Simulate an SMP system with n CPUs. On the PC target, up to 255 CPUs 176 are supported. On Sparc32 target, Linux limits the number of usable 177 CPUs to 4. For the PC target, the number of cores per die, the 178 number of threads per cores, the number of dies per packages and the 179 total number of sockets can be specified. Missing values will be 180 computed. If any on the three values is given, the total number of 181 CPUs n can be omitted. maxcpus specifies the maximum number of 182 hotpluggable CPUs. 183ERST 184 185DEF("numa", HAS_ARG, QEMU_OPTION_numa, 186 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 187 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 188 "-numa dist,src=source,dst=destination,val=distance\n" 189 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n" 190 "-numa hmat-lb,initiator=node,target=node,hierarchy=memory|first-level|second-level|third-level,data-type=access-latency|read-latency|write-latency[,latency=lat][,bandwidth=bw]\n" 191 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n", 192 QEMU_ARCH_ALL) 193SRST 194``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 195 \ 196``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 197 \ 198``-numa dist,src=source,dst=destination,val=distance`` 199 \ 200``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]`` 201 \ 202``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]`` 203 \ 204``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]`` 205 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA 206 distance from a source node to a destination node. Set the ACPI 207 Heterogeneous Memory Attributes for the given nodes. 208 209 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and 210 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a 211 contiguous range of CPU indexes (or a single VCPU if lastcpu is 212 omitted). A non-contiguous set of VCPUs can be represented by 213 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is 214 omitted on all nodes, VCPUs are automatically split between them. 215 216 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a 217 NUMA node: 218 219 :: 220 221 -numa node,cpus=0-2,cpus=5 222 223 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option 224 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to 225 assign CPU objects to a node using topology layout properties of 226 CPU. The set of properties is machine specific, and depends on used 227 machine type/'\ ``smp``\ ' options. It could be queried with 228 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ ' 229 property specifies node to which CPU object will be assigned, it's 230 required for node to be declared with '\ ``node``\ ' option before 231 it's used with '\ ``cpu``\ ' option. 232 233 For example: 234 235 :: 236 237 -M pc \ 238 -smp 1,sockets=2,maxcpus=2 \ 239 -numa node,nodeid=0 -numa node,nodeid=1 \ 240 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1 241 242 '\ ``mem``\ ' assigns a given RAM amount to a node. '\ ``memdev``\ ' 243 assigns RAM from a given memory backend device to a node. If 244 '\ ``mem``\ ' and '\ ``memdev``\ ' are omitted in all nodes, RAM is 245 split equally between them. 246 247 '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive. 248 Furthermore, if one node uses '\ ``memdev``\ ', all of them have to 249 use it. 250 251 '\ ``initiator``\ ' is an additional option that points to an 252 initiator NUMA node that has best performance (the lowest latency or 253 largest bandwidth) to this NUMA node. Note that this option can be 254 set only when the machine property 'hmat' is set to 'on'. 255 256 Following example creates a machine with 2 NUMA nodes, node 0 has 257 CPU. node 1 has only memory, and its initiator is node 0. Note that 258 because node 0 has CPU, by default the initiator of node 0 is itself 259 and must be itself. 260 261 :: 262 263 -machine hmat=on \ 264 -m 2G,slots=2,maxmem=4G \ 265 -object memory-backend-ram,size=1G,id=m0 \ 266 -object memory-backend-ram,size=1G,id=m1 \ 267 -numa node,nodeid=0,memdev=m0 \ 268 -numa node,nodeid=1,memdev=m1,initiator=0 \ 269 -smp 2,sockets=2,maxcpus=2 \ 270 -numa cpu,node-id=0,socket-id=0 \ 271 -numa cpu,node-id=0,socket-id=1 272 273 source and destination are NUMA node IDs. distance is the NUMA 274 distance from source to destination. The distance from a node to 275 itself is always 10. If any pair of nodes is given a distance, then 276 all pairs must be given distances. Although, when distances are only 277 given in one direction for each pair of nodes, then the distances in 278 the opposite directions are assumed to be the same. If, however, an 279 asymmetrical pair of distances is given for even one node pair, then 280 all node pairs must be provided distance values for both directions, 281 even when they are symmetrical. When a node is unreachable from 282 another node, set the pair's distance to 255. 283 284 Note that the -``numa`` option doesn't allocate any of the specified 285 resources, it just assigns existing resources to NUMA nodes. This 286 means that one still has to use the ``-m``, ``-smp`` options to 287 allocate RAM and VCPUs respectively. 288 289 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth 290 Information between initiator and target NUMA nodes in ACPI 291 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can 292 create memory requests, usually it has one or more processors. 293 Target NUMA node contains addressable memory. 294 295 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is 296 the memory hierarchy of the target NUMA node: if hierarchy is 297 'memory', the structure represents the memory performance; if 298 hierarchy is 'first-level\|second-level\|third-level', this 299 structure represents aggregated performance of memory side caches 300 for each domain. type of 'data-type' is type of data represented by 301 this structure instance: if 'hierarchy' is 'memory', 'data-type' is 302 'access\|read\|write' latency or 'access\|read\|write' bandwidth of 303 the target memory; if 'hierarchy' is 304 'first-level\|second-level\|third-level', 'data-type' is 305 'access\|read\|write' hit latency or 'access\|read\|write' hit 306 bandwidth of the target memory side cache. 307 308 lat is latency value in nanoseconds. bw is bandwidth value, the 309 possible value and units are NUM[M\|G\|T], mean that the bandwidth 310 value are NUM byte per second (or MB/s, GB/s or TB/s depending on 311 used suffix). Note that if latency or bandwidth value is 0, means 312 the corresponding latency or bandwidth information is not provided. 313 314 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory 315 belongs. size is the size of memory side cache in bytes. level is 316 the cache level described in this structure, note that the cache 317 level 0 should not be used with '\ ``hmat-cache``\ ' option. 318 associativity is the cache associativity, the possible value is 319 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy 320 is the write policy. line is the cache Line size in bytes. 321 322 For example, the following options describe 2 NUMA nodes. Node 0 has 323 2 cpus and a ram, node 1 has only a ram. The processors in node 0 324 access memory in node 0 with access-latency 5 nanoseconds, 325 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access 326 memory in NUMA node 1 with access-latency 10 nanoseconds, 327 access-bandwidth is 100 MB/s. And for memory side cache information, 328 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB, 329 policy is write-back, the cache Line size is 8 bytes: 330 331 :: 332 333 -machine hmat=on \ 334 -m 2G \ 335 -object memory-backend-ram,size=1G,id=m0 \ 336 -object memory-backend-ram,size=1G,id=m1 \ 337 -smp 2 \ 338 -numa node,nodeid=0,memdev=m0 \ 339 -numa node,nodeid=1,memdev=m1,initiator=0 \ 340 -numa cpu,node-id=0,socket-id=0 \ 341 -numa cpu,node-id=0,socket-id=1 \ 342 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \ 343 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \ 344 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \ 345 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \ 346 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \ 347 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8 348ERST 349 350DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd, 351 "-add-fd fd=fd,set=set[,opaque=opaque]\n" 352 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL) 353SRST 354``-add-fd fd=fd,set=set[,opaque=opaque]`` 355 Add a file descriptor to an fd set. Valid options are: 356 357 ``fd=fd`` 358 This option defines the file descriptor of which a duplicate is 359 added to fd set. The file descriptor cannot be stdin, stdout, or 360 stderr. 361 362 ``set=set`` 363 This option defines the ID of the fd set to add the file 364 descriptor to. 365 366 ``opaque=opaque`` 367 This option defines a free-form string that can be used to 368 describe fd. 369 370 You can open an image using pre-opened file descriptors from an fd 371 set: 372 373 .. parsed-literal:: 374 375 |qemu_system| \ 376 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \ 377 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \ 378 -drive file=/dev/fdset/2,index=0,media=disk 379ERST 380 381DEF("set", HAS_ARG, QEMU_OPTION_set, 382 "-set group.id.arg=value\n" 383 " set <arg> parameter for item <id> of type <group>\n" 384 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL) 385SRST 386``-set group.id.arg=value`` 387 Set parameter arg for item id of type group 388ERST 389 390DEF("global", HAS_ARG, QEMU_OPTION_global, 391 "-global driver.property=value\n" 392 "-global driver=driver,property=property,value=value\n" 393 " set a global default for a driver property\n", 394 QEMU_ARCH_ALL) 395SRST 396``-global driver.prop=value`` 397 \ 398``-global driver=driver,property=property,value=value`` 399 Set default value of driver's property prop to value, e.g.: 400 401 .. parsed-literal:: 402 403 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img 404 405 In particular, you can use this to set driver properties for devices 406 which are created automatically by the machine model. To create a 407 device which is not created automatically and set properties on it, 408 use -``device``. 409 410 -global driver.prop=value is shorthand for -global 411 driver=driver,property=prop,value=value. The longhand syntax works 412 even when driver contains a dot. 413ERST 414 415DEF("boot", HAS_ARG, QEMU_OPTION_boot, 416 "-boot [order=drives][,once=drives][,menu=on|off]\n" 417 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n" 418 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n" 419 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n" 420 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n" 421 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n", 422 QEMU_ARCH_ALL) 423SRST 424``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]`` 425 Specify boot order drives as a string of drive letters. Valid drive 426 letters depend on the target architecture. The x86 PC uses: a, b 427 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p 428 (Etherboot from network adapter 1-4), hard disk boot is the default. 429 To apply a particular boot order only on the first startup, specify 430 it via ``once``. Note that the ``order`` or ``once`` parameter 431 should not be used together with the ``bootindex`` property of 432 devices, since the firmware implementations normally do not support 433 both at the same time. 434 435 Interactive boot menus/prompts can be enabled via ``menu=on`` as far 436 as firmware/BIOS supports them. The default is non-interactive boot. 437 438 A splash picture could be passed to bios, enabling user to show it 439 as logo, when option splash=sp\_name is given and menu=on, If 440 firmware/BIOS supports them. Currently Seabios for X86 system 441 support it. limitation: The splash file could be a jpeg file or a 442 BMP file in 24 BPP format(true color). The resolution should be 443 supported by the SVGA mode, so the recommended is 320x240, 640x480, 444 800x640. 445 446 A timeout could be passed to bios, guest will pause for rb\_timeout 447 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will 448 not reboot, qemu passes '-1' to bios by default. Currently Seabios 449 for X86 system support it. 450 451 Do strict boot via ``strict=on`` as far as firmware/BIOS supports 452 it. This only effects when boot priority is changed by bootindex 453 options. The default is non-strict boot. 454 455 .. parsed-literal:: 456 457 # try to boot from network first, then from hard disk 458 |qemu_system_x86| -boot order=nc 459 # boot from CD-ROM first, switch back to default order after reboot 460 |qemu_system_x86| -boot once=d 461 # boot with a splash picture for 5 seconds. 462 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000 463 464 Note: The legacy format '-boot drives' is still supported but its 465 use is discouraged as it may be removed from future versions. 466ERST 467 468DEF("m", HAS_ARG, QEMU_OPTION_m, 469 "-m [size=]megs[,slots=n,maxmem=size]\n" 470 " configure guest RAM\n" 471 " size: initial amount of guest memory\n" 472 " slots: number of hotplug slots (default: none)\n" 473 " maxmem: maximum amount of guest memory (default: none)\n" 474 "NOTE: Some architectures might enforce a specific granularity\n", 475 QEMU_ARCH_ALL) 476SRST 477``-m [size=]megs[,slots=n,maxmem=size]`` 478 Sets guest startup RAM size to megs megabytes. Default is 128 MiB. 479 Optionally, a suffix of "M" or "G" can be used to signify a value in 480 megabytes or gigabytes respectively. Optional pair slots, maxmem 481 could be used to set amount of hotpluggable memory slots and maximum 482 amount of memory. Note that maxmem must be aligned to the page size. 483 484 For example, the following command-line sets the guest startup RAM 485 size to 1GB, creates 3 slots to hotplug additional memory and sets 486 the maximum memory the guest can reach to 4GB: 487 488 .. parsed-literal:: 489 490 |qemu_system| -m 1G,slots=3,maxmem=4G 491 492 If slots and maxmem are not specified, memory hotplug won't be 493 enabled and the guest startup RAM will never increase. 494ERST 495 496DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath, 497 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL) 498SRST 499``-mem-path path`` 500 Allocate guest RAM from a temporarily created file in path. 501ERST 502 503DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc, 504 "-mem-prealloc preallocate guest memory (use with -mem-path)\n", 505 QEMU_ARCH_ALL) 506SRST 507``-mem-prealloc`` 508 Preallocate memory when using -mem-path. 509ERST 510 511DEF("k", HAS_ARG, QEMU_OPTION_k, 512 "-k language use keyboard layout (for example 'fr' for French)\n", 513 QEMU_ARCH_ALL) 514SRST 515``-k language`` 516 Use keyboard layout language (for example ``fr`` for French). This 517 option is only needed where it is not easy to get raw PC keycodes 518 (e.g. on Macs, with some X11 servers or with a VNC or curses 519 display). You don't normally need to use it on PC/Linux or 520 PC/Windows hosts. 521 522 The available layouts are: 523 524 :: 525 526 ar de-ch es fo fr-ca hu ja mk no pt-br sv 527 da en-gb et fr fr-ch is lt nl pl ru th 528 de en-us fi fr-be hr it lv nl-be pt sl tr 529 530 The default is ``en-us``. 531ERST 532 533 534HXCOMM Deprecated by -audiodev 535DEF("audio-help", 0, QEMU_OPTION_audio_help, 536 "-audio-help show -audiodev equivalent of the currently specified audio settings\n", 537 QEMU_ARCH_ALL) 538SRST 539``-audio-help`` 540 Will show the -audiodev equivalent of the currently specified 541 (deprecated) environment variables. 542ERST 543 544DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev, 545 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n" 546 " specifies the audio backend to use\n" 547 " id= identifier of the backend\n" 548 " timer-period= timer period in microseconds\n" 549 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n" 550 " in|out.fixed-settings= use fixed settings for host audio\n" 551 " in|out.frequency= frequency to use with fixed settings\n" 552 " in|out.channels= number of channels to use with fixed settings\n" 553 " in|out.format= sample format to use with fixed settings\n" 554 " valid values: s8, s16, s32, u8, u16, u32, f32\n" 555 " in|out.voices= number of voices to use\n" 556 " in|out.buffer-length= length of buffer in microseconds\n" 557 "-audiodev none,id=id,[,prop[=value][,...]]\n" 558 " dummy driver that discards all output\n" 559#ifdef CONFIG_AUDIO_ALSA 560 "-audiodev alsa,id=id[,prop[=value][,...]]\n" 561 " in|out.dev= name of the audio device to use\n" 562 " in|out.period-length= length of period in microseconds\n" 563 " in|out.try-poll= attempt to use poll mode\n" 564 " threshold= threshold (in microseconds) when playback starts\n" 565#endif 566#ifdef CONFIG_AUDIO_COREAUDIO 567 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n" 568 " in|out.buffer-count= number of buffers\n" 569#endif 570#ifdef CONFIG_AUDIO_DSOUND 571 "-audiodev dsound,id=id[,prop[=value][,...]]\n" 572 " latency= add extra latency to playback in microseconds\n" 573#endif 574#ifdef CONFIG_AUDIO_OSS 575 "-audiodev oss,id=id[,prop[=value][,...]]\n" 576 " in|out.dev= path of the audio device to use\n" 577 " in|out.buffer-count= number of buffers\n" 578 " in|out.try-poll= attempt to use poll mode\n" 579 " try-mmap= try using memory mapped access\n" 580 " exclusive= open device in exclusive mode\n" 581 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n" 582#endif 583#ifdef CONFIG_AUDIO_PA 584 "-audiodev pa,id=id[,prop[=value][,...]]\n" 585 " server= PulseAudio server address\n" 586 " in|out.name= source/sink device name\n" 587 " in|out.latency= desired latency in microseconds\n" 588#endif 589#ifdef CONFIG_AUDIO_SDL 590 "-audiodev sdl,id=id[,prop[=value][,...]]\n" 591#endif 592#ifdef CONFIG_SPICE 593 "-audiodev spice,id=id[,prop[=value][,...]]\n" 594#endif 595 "-audiodev wav,id=id[,prop[=value][,...]]\n" 596 " path= path of wav file to record\n", 597 QEMU_ARCH_ALL) 598SRST 599``-audiodev [driver=]driver,id=id[,prop[=value][,...]]`` 600 Adds a new audio backend driver identified by id. There are global 601 and driver specific properties. Some values can be set differently 602 for input and output, they're marked with ``in|out.``. You can set 603 the input's property with ``in.prop`` and the output's property with 604 ``out.prop``. For example: 605 606 :: 607 608 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000 609 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified 610 611 NOTE: parameter validation is known to be incomplete, in many cases 612 specifying an invalid option causes QEMU to print an error message 613 and continue emulation without sound. 614 615 Valid global options are: 616 617 ``id=identifier`` 618 Identifies the audio backend. 619 620 ``timer-period=period`` 621 Sets the timer period used by the audio subsystem in 622 microseconds. Default is 10000 (10 ms). 623 624 ``in|out.mixing-engine=on|off`` 625 Use QEMU's mixing engine to mix all streams inside QEMU and 626 convert audio formats when not supported by the backend. When 627 off, fixed-settings must be off too. Note that disabling this 628 option means that the selected backend must support multiple 629 streams and the audio formats used by the virtual cards, 630 otherwise you'll get no sound. It's not recommended to disable 631 this option unless you want to use 5.1 or 7.1 audio, as mixing 632 engine only supports mono and stereo audio. Default is on. 633 634 ``in|out.fixed-settings=on|off`` 635 Use fixed settings for host audio. When off, it will change 636 based on how the guest opens the sound card. In this case you 637 must not specify frequency, channels or format. Default is on. 638 639 ``in|out.frequency=frequency`` 640 Specify the frequency to use when using fixed-settings. Default 641 is 44100Hz. 642 643 ``in|out.channels=channels`` 644 Specify the number of channels to use when using fixed-settings. 645 Default is 2 (stereo). 646 647 ``in|out.format=format`` 648 Specify the sample format to use when using fixed-settings. 649 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``, 650 ``u32``, ``f32``. Default is ``s16``. 651 652 ``in|out.voices=voices`` 653 Specify the number of voices to use. Default is 1. 654 655 ``in|out.buffer-length=usecs`` 656 Sets the size of the buffer in microseconds. 657 658``-audiodev none,id=id[,prop[=value][,...]]`` 659 Creates a dummy backend that discards all outputs. This backend has 660 no backend specific properties. 661 662``-audiodev alsa,id=id[,prop[=value][,...]]`` 663 Creates backend using the ALSA. This backend is only available on 664 Linux. 665 666 ALSA specific options are: 667 668 ``in|out.dev=device`` 669 Specify the ALSA device to use for input and/or output. Default 670 is ``default``. 671 672 ``in|out.period-length=usecs`` 673 Sets the period length in microseconds. 674 675 ``in|out.try-poll=on|off`` 676 Attempt to use poll mode with the device. Default is on. 677 678 ``threshold=threshold`` 679 Threshold (in microseconds) when playback starts. Default is 0. 680 681``-audiodev coreaudio,id=id[,prop[=value][,...]]`` 682 Creates a backend using Apple's Core Audio. This backend is only 683 available on Mac OS and only supports playback. 684 685 Core Audio specific options are: 686 687 ``in|out.buffer-count=count`` 688 Sets the count of the buffers. 689 690``-audiodev dsound,id=id[,prop[=value][,...]]`` 691 Creates a backend using Microsoft's DirectSound. This backend is 692 only available on Windows and only supports playback. 693 694 DirectSound specific options are: 695 696 ``latency=usecs`` 697 Add extra usecs microseconds latency to playback. Default is 698 10000 (10 ms). 699 700``-audiodev oss,id=id[,prop[=value][,...]]`` 701 Creates a backend using OSS. This backend is available on most 702 Unix-like systems. 703 704 OSS specific options are: 705 706 ``in|out.dev=device`` 707 Specify the file name of the OSS device to use. Default is 708 ``/dev/dsp``. 709 710 ``in|out.buffer-count=count`` 711 Sets the count of the buffers. 712 713 ``in|out.try-poll=on|of`` 714 Attempt to use poll mode with the device. Default is on. 715 716 ``try-mmap=on|off`` 717 Try using memory mapped device access. Default is off. 718 719 ``exclusive=on|off`` 720 Open the device in exclusive mode (vmix won't work in this 721 case). Default is off. 722 723 ``dsp-policy=policy`` 724 Sets the timing policy (between 0 and 10, where smaller number 725 means smaller latency but higher CPU usage). Use -1 to use 726 buffer sizes specified by ``buffer`` and ``buffer-count``. This 727 option is ignored if you do not have OSS 4. Default is 5. 728 729``-audiodev pa,id=id[,prop[=value][,...]]`` 730 Creates a backend using PulseAudio. This backend is available on 731 most systems. 732 733 PulseAudio specific options are: 734 735 ``server=server`` 736 Sets the PulseAudio server to connect to. 737 738 ``in|out.name=sink`` 739 Use the specified source/sink for recording/playback. 740 741 ``in|out.latency=usecs`` 742 Desired latency in microseconds. The PulseAudio server will try 743 to honor this value but actual latencies may be lower or higher. 744 745``-audiodev sdl,id=id[,prop[=value][,...]]`` 746 Creates a backend using SDL. This backend is available on most 747 systems, but you should use your platform's native backend if 748 possible. This backend has no backend specific properties. 749 750``-audiodev spice,id=id[,prop[=value][,...]]`` 751 Creates a backend that sends audio through SPICE. This backend 752 requires ``-spice`` and automatically selected in that case, so 753 usually you can ignore this option. This backend has no backend 754 specific properties. 755 756``-audiodev wav,id=id[,prop[=value][,...]]`` 757 Creates a backend that writes audio to a WAV file. 758 759 Backend specific options are: 760 761 ``path=path`` 762 Write recorded audio into the specified file. Default is 763 ``qemu.wav``. 764ERST 765 766DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw, 767 "-soundhw c1,... enable audio support\n" 768 " and only specified sound cards (comma separated list)\n" 769 " use '-soundhw help' to get the list of supported cards\n" 770 " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL) 771SRST 772``-soundhw card1[,card2,...] or -soundhw all`` 773 Enable audio and selected sound hardware. Use 'help' to print all 774 available sound hardware. For example: 775 776 .. parsed-literal:: 777 778 |qemu_system_x86| -soundhw sb16,adlib disk.img 779 |qemu_system_x86| -soundhw es1370 disk.img 780 |qemu_system_x86| -soundhw ac97 disk.img 781 |qemu_system_x86| -soundhw hda disk.img 782 |qemu_system_x86| -soundhw all disk.img 783 |qemu_system_x86| -soundhw help 784 785 Note that Linux's i810\_audio OSS kernel (for AC97) module might 786 require manually specifying clocking. 787 788 :: 789 790 modprobe i810_audio clocking=48000 791ERST 792 793DEF("device", HAS_ARG, QEMU_OPTION_device, 794 "-device driver[,prop[=value][,...]]\n" 795 " add device (based on driver)\n" 796 " prop=value,... sets driver properties\n" 797 " use '-device help' to print all possible drivers\n" 798 " use '-device driver,help' to print all possible properties\n", 799 QEMU_ARCH_ALL) 800SRST 801``-device driver[,prop[=value][,...]]`` 802 Add device driver. prop=value sets driver properties. Valid 803 properties depend on the driver. To get help on possible drivers and 804 properties, use ``-device help`` and ``-device driver,help``. 805 806 Some drivers are: 807 808``-device ipmi-bmc-sim,id=id[,slave_addr=val][,sdrfile=file][,furareasize=val][,furdatafile=file][,guid=uuid]`` 809 Add an IPMI BMC. This is a simulation of a hardware management 810 interface processor that normally sits on a system. It provides a 811 watchdog and the ability to reset and power control the system. You 812 need to connect this to an IPMI interface to make it useful 813 814 The IPMI slave address to use for the BMC. The default is 0x20. This 815 address is the BMC's address on the I2C network of management 816 controllers. If you don't know what this means, it is safe to ignore 817 it. 818 819 ``id=id`` 820 The BMC id for interfaces to use this device. 821 822 ``slave_addr=val`` 823 Define slave address to use for the BMC. The default is 0x20. 824 825 ``sdrfile=file`` 826 file containing raw Sensor Data Records (SDR) data. The default 827 is none. 828 829 ``fruareasize=val`` 830 size of a Field Replaceable Unit (FRU) area. The default is 831 1024. 832 833 ``frudatafile=file`` 834 file containing raw Field Replaceable Unit (FRU) inventory data. 835 The default is none. 836 837 ``guid=uuid`` 838 value for the GUID for the BMC, in standard UUID format. If this 839 is set, get "Get GUID" command to the BMC will return it. 840 Otherwise "Get GUID" will return an error. 841 842``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]`` 843 Add a connection to an external IPMI BMC simulator. Instead of 844 locally emulating the BMC like the above item, instead connect to an 845 external entity that provides the IPMI services. 846 847 A connection is made to an external BMC simulator. If you do this, 848 it is strongly recommended that you use the "reconnect=" chardev 849 option to reconnect to the simulator if the connection is lost. Note 850 that if this is not used carefully, it can be a security issue, as 851 the interface has the ability to send resets, NMIs, and power off 852 the VM. It's best if QEMU makes a connection to an external 853 simulator running on a secure port on localhost, so neither the 854 simulator nor QEMU is exposed to any outside network. 855 856 See the "lanserv/README.vm" file in the OpenIPMI library for more 857 details on the external interface. 858 859``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]`` 860 Add a KCS IPMI interafce on the ISA bus. This also adds a 861 corresponding ACPI and SMBIOS entries, if appropriate. 862 863 ``bmc=id`` 864 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern 865 above. 866 867 ``ioport=val`` 868 Define the I/O address of the interface. The default is 0xca0 869 for KCS. 870 871 ``irq=val`` 872 Define the interrupt to use. The default is 5. To disable 873 interrupts, set this to 0. 874 875``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]`` 876 Like the KCS interface, but defines a BT interface. The default port 877 is 0xe4 and the default interrupt is 5. 878ERST 879 880DEF("name", HAS_ARG, QEMU_OPTION_name, 881 "-name string1[,process=string2][,debug-threads=on|off]\n" 882 " set the name of the guest\n" 883 " string1 sets the window title and string2 the process name\n" 884 " When debug-threads is enabled, individual threads are given a separate name\n" 885 " NOTE: The thread names are for debugging and not a stable API.\n", 886 QEMU_ARCH_ALL) 887SRST 888``-name name`` 889 Sets the name of the guest. This name will be displayed in the SDL 890 window caption. The name will also be used for the VNC server. Also 891 optionally set the top visible process name in Linux. Naming of 892 individual threads can also be enabled on Linux to aid debugging. 893ERST 894 895DEF("uuid", HAS_ARG, QEMU_OPTION_uuid, 896 "-uuid %08x-%04x-%04x-%04x-%012x\n" 897 " specify machine UUID\n", QEMU_ARCH_ALL) 898SRST 899``-uuid uuid`` 900 Set system UUID. 901ERST 902 903DEFHEADING() 904 905DEFHEADING(Block device options:) 906 907DEF("fda", HAS_ARG, QEMU_OPTION_fda, 908 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL) 909DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL) 910SRST 911``-fda file`` 912 \ 913``-fdb file`` 914 Use file as floppy disk 0/1 image (see 915 :ref:`disk_005fimages`). 916ERST 917 918DEF("hda", HAS_ARG, QEMU_OPTION_hda, 919 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL) 920DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL) 921DEF("hdc", HAS_ARG, QEMU_OPTION_hdc, 922 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL) 923DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL) 924SRST 925``-hda file`` 926 \ 927``-hdb file`` 928 \ 929``-hdc file`` 930 \ 931``-hdd file`` 932 Use file as hard disk 0, 1, 2 or 3 image (see 933 :ref:`disk_005fimages`). 934ERST 935 936DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom, 937 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n", 938 QEMU_ARCH_ALL) 939SRST 940``-cdrom file`` 941 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at 942 the same time). You can use the host CD-ROM by using ``/dev/cdrom`` 943 as filename. 944ERST 945 946DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev, 947 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n" 948 " [,cache.direct=on|off][,cache.no-flush=on|off]\n" 949 " [,read-only=on|off][,auto-read-only=on|off]\n" 950 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n" 951 " [,driver specific parameters...]\n" 952 " configure a block backend\n", QEMU_ARCH_ALL) 953SRST 954``-blockdev option[,option[,option[,...]]]`` 955 Define a new block driver node. Some of the options apply to all 956 block drivers, other options are only accepted for a specific block 957 driver. See below for a list of generic options and options for the 958 most common block drivers. 959 960 Options that expect a reference to another node (e.g. ``file``) can 961 be given in two ways. Either you specify the node name of an already 962 existing node (file=node-name), or you define a new node inline, 963 adding options for the referenced node after a dot 964 (file.filename=path,file.aio=native). 965 966 A block driver node created with ``-blockdev`` can be used for a 967 guest device by specifying its node name for the ``drive`` property 968 in a ``-device`` argument that defines a block device. 969 970 ``Valid options for any block driver node:`` 971 ``driver`` 972 Specifies the block driver to use for the given node. 973 974 ``node-name`` 975 This defines the name of the block driver node by which it 976 will be referenced later. The name must be unique, i.e. it 977 must not match the name of a different block driver node, or 978 (if you use ``-drive`` as well) the ID of a drive. 979 980 If no node name is specified, it is automatically generated. 981 The generated node name is not intended to be predictable 982 and changes between QEMU invocations. For the top level, an 983 explicit node name must be specified. 984 985 ``read-only`` 986 Open the node read-only. Guest write attempts will fail. 987 988 Note that some block drivers support only read-only access, 989 either generally or in certain configurations. In this case, 990 the default value ``read-only=off`` does not work and the 991 option must be specified explicitly. 992 993 ``auto-read-only`` 994 If ``auto-read-only=on`` is set, QEMU may fall back to 995 read-only usage even when ``read-only=off`` is requested, or 996 even switch between modes as needed, e.g. depending on 997 whether the image file is writable or whether a writing user 998 is attached to the node. 999 1000 ``force-share`` 1001 Override the image locking system of QEMU by forcing the 1002 node to utilize weaker shared access for permissions where 1003 it would normally request exclusive access. When there is 1004 the potential for multiple instances to have the same file 1005 open (whether this invocation of QEMU is the first or the 1006 second instance), both instances must permit shared access 1007 for the second instance to succeed at opening the file. 1008 1009 Enabling ``force-share=on`` requires ``read-only=on``. 1010 1011 ``cache.direct`` 1012 The host page cache can be avoided with ``cache.direct=on``. 1013 This will attempt to do disk IO directly to the guest's 1014 memory. QEMU may still perform an internal copy of the data. 1015 1016 ``cache.no-flush`` 1017 In case you don't care about data integrity over host 1018 failures, you can use ``cache.no-flush=on``. This option 1019 tells QEMU that it never needs to write any data to the disk 1020 but can instead keep things in cache. If anything goes 1021 wrong, like your host losing power, the disk storage getting 1022 disconnected accidentally, etc. your image will most 1023 probably be rendered unusable. 1024 1025 ``discard=discard`` 1026 discard is one of "ignore" (or "off") or "unmap" (or "on") 1027 and controls whether ``discard`` (also known as ``trim`` or 1028 ``unmap``) requests are ignored or passed to the filesystem. 1029 Some machine types may not support discard requests. 1030 1031 ``detect-zeroes=detect-zeroes`` 1032 detect-zeroes is "off", "on" or "unmap" and enables the 1033 automatic conversion of plain zero writes by the OS to 1034 driver specific optimized zero write commands. You may even 1035 choose "unmap" if discard is set to "unmap" to allow a zero 1036 write to be converted to an ``unmap`` operation. 1037 1038 ``Driver-specific options for file`` 1039 This is the protocol-level block driver for accessing regular 1040 files. 1041 1042 ``filename`` 1043 The path to the image file in the local filesystem 1044 1045 ``aio`` 1046 Specifies the AIO backend (threads/native, default: threads) 1047 1048 ``locking`` 1049 Specifies whether the image file is protected with Linux OFD 1050 / POSIX locks. The default is to use the Linux Open File 1051 Descriptor API if available, otherwise no lock is applied. 1052 (auto/on/off, default: auto) 1053 1054 Example: 1055 1056 :: 1057 1058 -blockdev driver=file,node-name=disk,filename=disk.img 1059 1060 ``Driver-specific options for raw`` 1061 This is the image format block driver for raw images. It is 1062 usually stacked on top of a protocol level block driver such as 1063 ``file``. 1064 1065 ``file`` 1066 Reference to or definition of the data source block driver 1067 node (e.g. a ``file`` driver node) 1068 1069 Example 1: 1070 1071 :: 1072 1073 -blockdev driver=file,node-name=disk_file,filename=disk.img 1074 -blockdev driver=raw,node-name=disk,file=disk_file 1075 1076 Example 2: 1077 1078 :: 1079 1080 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img 1081 1082 ``Driver-specific options for qcow2`` 1083 This is the image format block driver for qcow2 images. It is 1084 usually stacked on top of a protocol level block driver such as 1085 ``file``. 1086 1087 ``file`` 1088 Reference to or definition of the data source block driver 1089 node (e.g. a ``file`` driver node) 1090 1091 ``backing`` 1092 Reference to or definition of the backing file block device 1093 (default is taken from the image file). It is allowed to 1094 pass ``null`` here in order to disable the default backing 1095 file. 1096 1097 ``lazy-refcounts`` 1098 Whether to enable the lazy refcounts feature (on/off; 1099 default is taken from the image file) 1100 1101 ``cache-size`` 1102 The maximum total size of the L2 table and refcount block 1103 caches in bytes (default: the sum of l2-cache-size and 1104 refcount-cache-size) 1105 1106 ``l2-cache-size`` 1107 The maximum size of the L2 table cache in bytes (default: if 1108 cache-size is not specified - 32M on Linux platforms, and 8M 1109 on non-Linux platforms; otherwise, as large as possible 1110 within the cache-size, while permitting the requested or the 1111 minimal refcount cache size) 1112 1113 ``refcount-cache-size`` 1114 The maximum size of the refcount block cache in bytes 1115 (default: 4 times the cluster size; or if cache-size is 1116 specified, the part of it which is not used for the L2 1117 cache) 1118 1119 ``cache-clean-interval`` 1120 Clean unused entries in the L2 and refcount caches. The 1121 interval is in seconds. The default value is 600 on 1122 supporting platforms, and 0 on other platforms. Setting it 1123 to 0 disables this feature. 1124 1125 ``pass-discard-request`` 1126 Whether discard requests to the qcow2 device should be 1127 forwarded to the data source (on/off; default: on if 1128 discard=unmap is specified, off otherwise) 1129 1130 ``pass-discard-snapshot`` 1131 Whether discard requests for the data source should be 1132 issued when a snapshot operation (e.g. deleting a snapshot) 1133 frees clusters in the qcow2 file (on/off; default: on) 1134 1135 ``pass-discard-other`` 1136 Whether discard requests for the data source should be 1137 issued on other occasions where a cluster gets freed 1138 (on/off; default: off) 1139 1140 ``overlap-check`` 1141 Which overlap checks to perform for writes to the image 1142 (none/constant/cached/all; default: cached). For details or 1143 finer granularity control refer to the QAPI documentation of 1144 ``blockdev-add``. 1145 1146 Example 1: 1147 1148 :: 1149 1150 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2 1151 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216 1152 1153 Example 2: 1154 1155 :: 1156 1157 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2 1158 1159 ``Driver-specific options for other drivers`` 1160 Please refer to the QAPI documentation of the ``blockdev-add`` 1161 QMP command. 1162ERST 1163 1164DEF("drive", HAS_ARG, QEMU_OPTION_drive, 1165 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" 1166 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" 1167 " [,snapshot=on|off][,rerror=ignore|stop|report]\n" 1168 " [,werror=ignore|stop|report|enospc][,id=name][,aio=threads|native]\n" 1169 " [,readonly=on|off][,copy-on-read=on|off]\n" 1170 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n" 1171 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n" 1172 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n" 1173 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n" 1174 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n" 1175 " [[,iops_size=is]]\n" 1176 " [[,group=g]]\n" 1177 " use 'file' as a drive image\n", QEMU_ARCH_ALL) 1178SRST 1179``-drive option[,option[,option[,...]]]`` 1180 Define a new drive. This includes creating a block driver node (the 1181 backend) as well as a guest device, and is mostly a shortcut for 1182 defining the corresponding ``-blockdev`` and ``-device`` options. 1183 1184 ``-drive`` accepts all options that are accepted by ``-blockdev``. 1185 In addition, it knows the following options: 1186 1187 ``file=file`` 1188 This option defines which disk image (see 1189 :ref:`disk_005fimages`) to use with this drive. If 1190 the filename contains comma, you must double it (for instance, 1191 "file=my,,file" to use file "my,file"). 1192 1193 Special files such as iSCSI devices can be specified using 1194 protocol specific URLs. See the section for "Device URL Syntax" 1195 for more information. 1196 1197 ``if=interface`` 1198 This option defines on which type on interface the drive is 1199 connected. Available types are: ide, scsi, sd, mtd, floppy, 1200 pflash, virtio, none. 1201 1202 ``bus=bus,unit=unit`` 1203 These options define where is connected the drive by defining 1204 the bus number and the unit id. 1205 1206 ``index=index`` 1207 This option defines where is connected the drive by using an 1208 index in the list of available connectors of a given interface 1209 type. 1210 1211 ``media=media`` 1212 This option defines the type of the media: disk or cdrom. 1213 1214 ``snapshot=snapshot`` 1215 snapshot is "on" or "off" and controls snapshot mode for the 1216 given drive (see ``-snapshot``). 1217 1218 ``cache=cache`` 1219 cache is "none", "writeback", "unsafe", "directsync" or 1220 "writethrough" and controls how the host cache is used to access 1221 block data. This is a shortcut that sets the ``cache.direct`` 1222 and ``cache.no-flush`` options (as in ``-blockdev``), and 1223 additionally ``cache.writeback``, which provides a default for 1224 the ``write-cache`` option of block guest devices (as in 1225 ``-device``). The modes correspond to the following settings: 1226 1227 ============= =============== ============ ============== 1228 \ cache.writeback cache.direct cache.no-flush 1229 ============= =============== ============ ============== 1230 writeback on off off 1231 none on on off 1232 writethrough off off off 1233 directsync off on off 1234 unsafe on off on 1235 ============= =============== ============ ============== 1236 1237 The default mode is ``cache=writeback``. 1238 1239 ``aio=aio`` 1240 aio is "threads", or "native" and selects between pthread based 1241 disk I/O and native Linux AIO. 1242 1243 ``format=format`` 1244 Specify which disk format will be used rather than detecting the 1245 format. Can be used to specify format=raw to avoid interpreting 1246 an untrusted format header. 1247 1248 ``werror=action,rerror=action`` 1249 Specify which action to take on write and read errors. Valid 1250 actions are: "ignore" (ignore the error and try to continue), 1251 "stop" (pause QEMU), "report" (report the error to the guest), 1252 "enospc" (pause QEMU only if the host disk is full; report the 1253 error to the guest otherwise). The default setting is 1254 ``werror=enospc`` and ``rerror=report``. 1255 1256 ``copy-on-read=copy-on-read`` 1257 copy-on-read is "on" or "off" and enables whether to copy read 1258 backing file sectors into the image file. 1259 1260 ``bps=b,bps_rd=r,bps_wr=w`` 1261 Specify bandwidth throttling limits in bytes per second, either 1262 for all request types or for reads or writes only. Small values 1263 can lead to timeouts or hangs inside the guest. A safe minimum 1264 for disks is 2 MB/s. 1265 1266 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm`` 1267 Specify bursts in bytes per second, either for all request types 1268 or for reads or writes only. Bursts allow the guest I/O to spike 1269 above the limit temporarily. 1270 1271 ``iops=i,iops_rd=r,iops_wr=w`` 1272 Specify request rate limits in requests per second, either for 1273 all request types or for reads or writes only. 1274 1275 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm`` 1276 Specify bursts in requests per second, either for all request 1277 types or for reads or writes only. Bursts allow the guest I/O to 1278 spike above the limit temporarily. 1279 1280 ``iops_size=is`` 1281 Let every is bytes of a request count as a new request for iops 1282 throttling purposes. Use this option to prevent guests from 1283 circumventing iops limits by sending fewer but larger requests. 1284 1285 ``group=g`` 1286 Join a throttling quota group with given name g. All drives that 1287 are members of the same group are accounted for together. Use 1288 this option to prevent guests from circumventing throttling 1289 limits by using many small disks instead of a single larger 1290 disk. 1291 1292 By default, the ``cache.writeback=on`` mode is used. It will report 1293 data writes as completed as soon as the data is present in the host 1294 page cache. This is safe as long as your guest OS makes sure to 1295 correctly flush disk caches where needed. If your guest OS does not 1296 handle volatile disk write caches correctly and your host crashes or 1297 loses power, then the guest may experience data corruption. 1298 1299 For such guests, you should consider using ``cache.writeback=off``. 1300 This means that the host page cache will be used to read and write 1301 data, but write notification will be sent to the guest only after 1302 QEMU has made sure to flush each write to the disk. Be aware that 1303 this has a major impact on performance. 1304 1305 When using the ``-snapshot`` option, unsafe caching is always used. 1306 1307 Copy-on-read avoids accessing the same backing file sectors 1308 repeatedly and is useful when the backing file is over a slow 1309 network. By default copy-on-read is off. 1310 1311 Instead of ``-cdrom`` you can use: 1312 1313 .. parsed-literal:: 1314 1315 |qemu_system| -drive file=file,index=2,media=cdrom 1316 1317 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use: 1318 1319 .. parsed-literal:: 1320 1321 |qemu_system| -drive file=file,index=0,media=disk 1322 |qemu_system| -drive file=file,index=1,media=disk 1323 |qemu_system| -drive file=file,index=2,media=disk 1324 |qemu_system| -drive file=file,index=3,media=disk 1325 1326 You can open an image using pre-opened file descriptors from an fd 1327 set: 1328 1329 .. parsed-literal:: 1330 1331 |qemu_system| \ 1332 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \ 1333 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \ 1334 -drive file=/dev/fdset/2,index=0,media=disk 1335 1336 You can connect a CDROM to the slave of ide0: 1337 1338 .. parsed-literal:: 1339 1340 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom 1341 1342 If you don't specify the "file=" argument, you define an empty 1343 drive: 1344 1345 .. parsed-literal:: 1346 1347 |qemu_system_x86| -drive if=ide,index=1,media=cdrom 1348 1349 Instead of ``-fda``, ``-fdb``, you can use: 1350 1351 .. parsed-literal:: 1352 1353 |qemu_system_x86| -drive file=file,index=0,if=floppy 1354 |qemu_system_x86| -drive file=file,index=1,if=floppy 1355 1356 By default, interface is "ide" and index is automatically 1357 incremented: 1358 1359 .. parsed-literal:: 1360 1361 |qemu_system_x86| -drive file=a -drive file=b" 1362 1363 is interpreted like: 1364 1365 .. parsed-literal:: 1366 1367 |qemu_system_x86| -hda a -hdb b 1368ERST 1369 1370DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock, 1371 "-mtdblock file use 'file' as on-board Flash memory image\n", 1372 QEMU_ARCH_ALL) 1373SRST 1374``-mtdblock file`` 1375 Use file as on-board Flash memory image. 1376ERST 1377 1378DEF("sd", HAS_ARG, QEMU_OPTION_sd, 1379 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL) 1380SRST 1381``-sd file`` 1382 Use file as SecureDigital card image. 1383ERST 1384 1385DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, 1386 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) 1387SRST 1388``-pflash file`` 1389 Use file as a parallel flash image. 1390ERST 1391 1392DEF("snapshot", 0, QEMU_OPTION_snapshot, 1393 "-snapshot write to temporary files instead of disk image files\n", 1394 QEMU_ARCH_ALL) 1395SRST 1396``-snapshot`` 1397 Write to temporary files instead of disk image files. In this case, 1398 the raw disk image you use is not written back. You can however 1399 force the write back by pressing C-a s (see 1400 :ref:`disk_005fimages`). 1401ERST 1402 1403DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev, 1404 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1405 " [,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode]\n" 1406 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n" 1407 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n" 1408 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n" 1409 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n" 1410 " [[,throttling.iops-size=is]]\n" 1411 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly]\n" 1412 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly]\n" 1413 "-fsdev synth,id=id\n", 1414 QEMU_ARCH_ALL) 1415 1416SRST 1417``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]`` 1418 \ 1419``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly]`` 1420 \ 1421``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly]`` 1422 \ 1423``-fsdev synth,id=id[,readonly]`` 1424 Define a new file system device. Valid options are: 1425 1426 ``local`` 1427 Accesses to the filesystem are done by QEMU. 1428 1429 ``proxy`` 1430 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1431 1432 ``synth`` 1433 Synthetic filesystem, only used by QTests. 1434 1435 ``id=id`` 1436 Specifies identifier for this device. 1437 1438 ``path=path`` 1439 Specifies the export path for the file system device. Files 1440 under this path will be available to the 9p client on the guest. 1441 1442 ``security_model=security_model`` 1443 Specifies the security model to be used for this export path. 1444 Supported security models are "passthrough", "mapped-xattr", 1445 "mapped-file" and "none". In "passthrough" security model, files 1446 are stored using the same credentials as they are created on the 1447 guest. This requires QEMU to run as root. In "mapped-xattr" 1448 security model, some of the file attributes like uid, gid, mode 1449 bits and link target are stored as file attributes. For 1450 "mapped-file" these attributes are stored in the hidden 1451 .virtfs\_metadata directory. Directories exported by this 1452 security model cannot interact with other unix tools. "none" 1453 security model is same as passthrough except the sever won't 1454 report failures if it fails to set file attributes like 1455 ownership. Security model is mandatory only for local fsdriver. 1456 Other fsdrivers (like proxy) don't take security model as a 1457 parameter. 1458 1459 ``writeout=writeout`` 1460 This is an optional argument. The only supported value is 1461 "immediate". This means that host page cache will be used to 1462 read and write data but write notification will be sent to the 1463 guest only when the data has been reported as written by the 1464 storage subsystem. 1465 1466 ``readonly`` 1467 Enables exporting 9p share as a readonly mount for guests. By 1468 default read-write access is given. 1469 1470 ``socket=socket`` 1471 Enables proxy filesystem driver to use passed socket file for 1472 communicating with virtfs-proxy-helper(1). 1473 1474 ``sock_fd=sock_fd`` 1475 Enables proxy filesystem driver to use passed socket descriptor 1476 for communicating with virtfs-proxy-helper(1). Usually a helper 1477 like libvirt will create socketpair and pass one of the fds as 1478 sock\_fd. 1479 1480 ``fmode=fmode`` 1481 Specifies the default mode for newly created files on the host. 1482 Works only with security models "mapped-xattr" and 1483 "mapped-file". 1484 1485 ``dmode=dmode`` 1486 Specifies the default mode for newly created directories on the 1487 host. Works only with security models "mapped-xattr" and 1488 "mapped-file". 1489 1490 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w`` 1491 Specify bandwidth throttling limits in bytes per second, either 1492 for all request types or for reads or writes only. 1493 1494 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm`` 1495 Specify bursts in bytes per second, either for all request types 1496 or for reads or writes only. Bursts allow the guest I/O to spike 1497 above the limit temporarily. 1498 1499 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w`` 1500 Specify request rate limits in requests per second, either for 1501 all request types or for reads or writes only. 1502 1503 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm`` 1504 Specify bursts in requests per second, either for all request 1505 types or for reads or writes only. Bursts allow the guest I/O to 1506 spike above the limit temporarily. 1507 1508 ``throttling.iops-size=is`` 1509 Let every is bytes of a request count as a new request for iops 1510 throttling purposes. 1511 1512 -fsdev option is used along with -device driver "virtio-9p-...". 1513 1514``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag`` 1515 Options for virtio-9p-... driver are: 1516 1517 ``type`` 1518 Specifies the variant to be used. Supported values are "pci", 1519 "ccw" or "device", depending on the machine type. 1520 1521 ``fsdev=id`` 1522 Specifies the id value specified along with -fsdev option. 1523 1524 ``mount_tag=mount_tag`` 1525 Specifies the tag name to be used by the guest to mount this 1526 export point. 1527ERST 1528 1529DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, 1530 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1531 " [,id=id][,writeout=immediate][,readonly][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n" 1532 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly]\n" 1533 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly]\n" 1534 "-virtfs synth,mount_tag=tag[,id=id][,readonly]\n", 1535 QEMU_ARCH_ALL) 1536 1537SRST 1538``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]`` 1539 \ 1540``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly]`` 1541 \ 1542``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly]`` 1543 \ 1544``-virtfs synth,mount_tag=mount_tag`` 1545 Define a new filesystem device and expose it to the guest using a 1546 virtio-9p-device. The general form of a Virtual File system 1547 pass-through options are: 1548 1549 ``local`` 1550 Accesses to the filesystem are done by QEMU. 1551 1552 ``proxy`` 1553 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1554 1555 ``synth`` 1556 Synthetic filesystem, only used by QTests. 1557 1558 ``id=id`` 1559 Specifies identifier for the filesystem device 1560 1561 ``path=path`` 1562 Specifies the export path for the file system device. Files 1563 under this path will be available to the 9p client on the guest. 1564 1565 ``security_model=security_model`` 1566 Specifies the security model to be used for this export path. 1567 Supported security models are "passthrough", "mapped-xattr", 1568 "mapped-file" and "none". In "passthrough" security model, files 1569 are stored using the same credentials as they are created on the 1570 guest. This requires QEMU to run as root. In "mapped-xattr" 1571 security model, some of the file attributes like uid, gid, mode 1572 bits and link target are stored as file attributes. For 1573 "mapped-file" these attributes are stored in the hidden 1574 .virtfs\_metadata directory. Directories exported by this 1575 security model cannot interact with other unix tools. "none" 1576 security model is same as passthrough except the sever won't 1577 report failures if it fails to set file attributes like 1578 ownership. Security model is mandatory only for local fsdriver. 1579 Other fsdrivers (like proxy) don't take security model as a 1580 parameter. 1581 1582 ``writeout=writeout`` 1583 This is an optional argument. The only supported value is 1584 "immediate". This means that host page cache will be used to 1585 read and write data but write notification will be sent to the 1586 guest only when the data has been reported as written by the 1587 storage subsystem. 1588 1589 ``readonly`` 1590 Enables exporting 9p share as a readonly mount for guests. By 1591 default read-write access is given. 1592 1593 ``socket=socket`` 1594 Enables proxy filesystem driver to use passed socket file for 1595 communicating with virtfs-proxy-helper(1). Usually a helper like 1596 libvirt will create socketpair and pass one of the fds as 1597 sock\_fd. 1598 1599 ``sock_fd`` 1600 Enables proxy filesystem driver to use passed 'sock\_fd' as the 1601 socket descriptor for interfacing with virtfs-proxy-helper(1). 1602 1603 ``fmode=fmode`` 1604 Specifies the default mode for newly created files on the host. 1605 Works only with security models "mapped-xattr" and 1606 "mapped-file". 1607 1608 ``dmode=dmode`` 1609 Specifies the default mode for newly created directories on the 1610 host. Works only with security models "mapped-xattr" and 1611 "mapped-file". 1612 1613 ``mount_tag=mount_tag`` 1614 Specifies the tag name to be used by the guest to mount this 1615 export point. 1616 1617 ``multidevs=multidevs`` 1618 Specifies how to deal with multiple devices being shared with a 1619 9p export. Supported behaviours are either "remap", "forbid" or 1620 "warn". The latter is the default behaviour on which virtfs 9p 1621 expects only one device to be shared with the same export, and 1622 if more than one device is shared and accessed via the same 9p 1623 export then only a warning message is logged (once) by qemu on 1624 host side. In order to avoid file ID collisions on guest you 1625 should either create a separate virtfs export for each device to 1626 be shared with guests (recommended way) or you might use "remap" 1627 instead which allows you to share multiple devices with only one 1628 export instead, which is achieved by remapping the original 1629 inode numbers from host to guest in a way that would prevent 1630 such collisions. Remapping inodes in such use cases is required 1631 because the original device IDs from host are never passed and 1632 exposed on guest. Instead all files of an export shared with 1633 virtfs always share the same device id on guest. So two files 1634 with identical inode numbers but from actually different devices 1635 on host would otherwise cause a file ID collision and hence 1636 potential misbehaviours on guest. "forbid" on the other hand 1637 assumes like "warn" that only one device is shared by the same 1638 export, however it will not only log a warning message but also 1639 deny access to additional devices on guest. Note though that 1640 "forbid" does currently not block all possible file access 1641 operations (e.g. readdir() would still return entries from other 1642 devices). 1643ERST 1644 1645DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi, 1646 "-iscsi [user=user][,password=password]\n" 1647 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n" 1648 " [,initiator-name=initiator-iqn][,id=target-iqn]\n" 1649 " [,timeout=timeout]\n" 1650 " iSCSI session parameters\n", QEMU_ARCH_ALL) 1651 1652SRST 1653``-iscsi`` 1654 Configure iSCSI session parameters. 1655ERST 1656 1657DEFHEADING() 1658 1659DEFHEADING(USB options:) 1660 1661DEF("usb", 0, QEMU_OPTION_usb, 1662 "-usb enable on-board USB host controller (if not enabled by default)\n", 1663 QEMU_ARCH_ALL) 1664SRST 1665``-usb`` 1666 Enable USB emulation on machine types with an on-board USB host 1667 controller (if not enabled by default). Note that on-board USB host 1668 controllers may not support USB 3.0. In this case 1669 ``-device qemu-xhci`` can be used instead on machines with PCI. 1670ERST 1671 1672DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice, 1673 "-usbdevice name add the host or guest USB device 'name'\n", 1674 QEMU_ARCH_ALL) 1675SRST 1676``-usbdevice devname`` 1677 Add the USB device devname. Note that this option is deprecated, 1678 please use ``-device usb-...`` instead. See 1679 :ref:`usb_005fdevices`. 1680 1681 ``mouse`` 1682 Virtual Mouse. This will override the PS/2 mouse emulation when 1683 activated. 1684 1685 ``tablet`` 1686 Pointer device that uses absolute coordinates (like a 1687 touchscreen). This means QEMU is able to report the mouse 1688 position without having to grab the mouse. Also overrides the 1689 PS/2 mouse emulation when activated. 1690 1691 ``braille`` 1692 Braille device. This will use BrlAPI to display the braille 1693 output on a real or fake device. 1694ERST 1695 1696DEFHEADING() 1697 1698DEFHEADING(Display options:) 1699 1700DEF("display", HAS_ARG, QEMU_OPTION_display, 1701#if defined(CONFIG_SPICE) 1702 "-display spice-app[,gl=on|off]\n" 1703#endif 1704#if defined(CONFIG_SDL) 1705 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off]\n" 1706 " [,window_close=on|off][,gl=on|core|es|off]\n" 1707#endif 1708#if defined(CONFIG_GTK) 1709 "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n" 1710#endif 1711#if defined(CONFIG_VNC) 1712 "-display vnc=<display>[,<optargs>]\n" 1713#endif 1714#if defined(CONFIG_CURSES) 1715 "-display curses[,charset=<encoding>]\n" 1716#endif 1717#if defined(CONFIG_OPENGL) 1718 "-display egl-headless[,rendernode=<file>]\n" 1719#endif 1720 "-display none\n" 1721 " select display backend type\n" 1722 " The default display is equivalent to\n " 1723#if defined(CONFIG_GTK) 1724 "\"-display gtk\"\n" 1725#elif defined(CONFIG_SDL) 1726 "\"-display sdl\"\n" 1727#elif defined(CONFIG_COCOA) 1728 "\"-display cocoa\"\n" 1729#elif defined(CONFIG_VNC) 1730 "\"-vnc localhost:0,to=99,id=default\"\n" 1731#else 1732 "\"-display none\"\n" 1733#endif 1734 , QEMU_ARCH_ALL) 1735SRST 1736``-display type`` 1737 Select type of display to use. This option is a replacement for the 1738 old style -sdl/-curses/... options. Use ``-display help`` to list 1739 the available display types. Valid values for type are 1740 1741 ``sdl`` 1742 Display video output via SDL (usually in a separate graphics 1743 window; see the SDL documentation for other possibilities). 1744 1745 ``curses`` 1746 Display video output via curses. For graphics device models 1747 which support a text mode, QEMU can display this output using a 1748 curses/ncurses interface. Nothing is displayed when the graphics 1749 device is in graphical mode or if the graphics device does not 1750 support a text mode. Generally only the VGA device models 1751 support text mode. The font charset used by the guest can be 1752 specified with the ``charset`` option, for example 1753 ``charset=CP850`` for IBM CP850 encoding. The default is 1754 ``CP437``. 1755 1756 ``none`` 1757 Do not display video output. The guest will still see an 1758 emulated graphics card, but its output will not be displayed to 1759 the QEMU user. This option differs from the -nographic option in 1760 that it only affects what is done with video output; -nographic 1761 also changes the destination of the serial and parallel port 1762 data. 1763 1764 ``gtk`` 1765 Display video output in a GTK window. This interface provides 1766 drop-down menus and other UI elements to configure and control 1767 the VM during runtime. 1768 1769 ``vnc`` 1770 Start a VNC server on display <arg> 1771 1772 ``egl-headless`` 1773 Offload all OpenGL operations to a local DRI device. For any 1774 graphical display, this display needs to be paired with either 1775 VNC or SPICE displays. 1776 1777 ``spice-app`` 1778 Start QEMU as a Spice server and launch the default Spice client 1779 application. The Spice server will redirect the serial consoles 1780 and QEMU monitors. (Since 4.0) 1781ERST 1782 1783DEF("nographic", 0, QEMU_OPTION_nographic, 1784 "-nographic disable graphical output and redirect serial I/Os to console\n", 1785 QEMU_ARCH_ALL) 1786SRST 1787``-nographic`` 1788 Normally, if QEMU is compiled with graphical window support, it 1789 displays output such as guest graphics, guest console, and the QEMU 1790 monitor in a window. With this option, you can totally disable 1791 graphical output so that QEMU is a simple command line application. 1792 The emulated serial port is redirected on the console and muxed with 1793 the monitor (unless redirected elsewhere explicitly). Therefore, you 1794 can still use QEMU to debug a Linux kernel with a serial console. 1795 Use C-a h for help on switching between the console and monitor. 1796ERST 1797 1798DEF("curses", 0, QEMU_OPTION_curses, 1799 "-curses shorthand for -display curses\n", 1800 QEMU_ARCH_ALL) 1801SRST 1802``-curses`` 1803 Normally, if QEMU is compiled with graphical window support, it 1804 displays output such as guest graphics, guest console, and the QEMU 1805 monitor in a window. With this option, QEMU can display the VGA 1806 output when in text mode using a curses/ncurses interface. Nothing 1807 is displayed in graphical mode. 1808ERST 1809 1810DEF("alt-grab", 0, QEMU_OPTION_alt_grab, 1811 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n", 1812 QEMU_ARCH_ALL) 1813SRST 1814``-alt-grab`` 1815 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that 1816 this also affects the special keys (for fullscreen, monitor-mode 1817 switching, etc). 1818ERST 1819 1820DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab, 1821 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n", 1822 QEMU_ARCH_ALL) 1823SRST 1824``-ctrl-grab`` 1825 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this 1826 also affects the special keys (for fullscreen, monitor-mode 1827 switching, etc). 1828ERST 1829 1830DEF("no-quit", 0, QEMU_OPTION_no_quit, 1831 "-no-quit disable SDL window close capability\n", QEMU_ARCH_ALL) 1832SRST 1833``-no-quit`` 1834 Disable SDL window close capability. 1835ERST 1836 1837DEF("sdl", 0, QEMU_OPTION_sdl, 1838 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL) 1839SRST 1840``-sdl`` 1841 Enable SDL. 1842ERST 1843 1844DEF("spice", HAS_ARG, QEMU_OPTION_spice, 1845 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n" 1846 " [,x509-key-file=<file>][,x509-key-password=<file>]\n" 1847 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n" 1848 " [,x509-dh-key-file=<file>][,addr=addr][,ipv4|ipv6|unix]\n" 1849 " [,tls-ciphers=<list>]\n" 1850 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n" 1851 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n" 1852 " [,sasl][,password=<secret>][,disable-ticketing]\n" 1853 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n" 1854 " [,jpeg-wan-compression=[auto|never|always]]\n" 1855 " [,zlib-glz-wan-compression=[auto|never|always]]\n" 1856 " [,streaming-video=[off|all|filter]][,disable-copy-paste]\n" 1857 " [,disable-agent-file-xfer][,agent-mouse=[on|off]]\n" 1858 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n" 1859 " [,gl=[on|off]][,rendernode=<file>]\n" 1860 " enable spice\n" 1861 " at least one of {port, tls-port} is mandatory\n", 1862 QEMU_ARCH_ALL) 1863SRST 1864``-spice option[,option[,...]]`` 1865 Enable the spice remote desktop protocol. Valid options are 1866 1867 ``port=<nr>`` 1868 Set the TCP port spice is listening on for plaintext channels. 1869 1870 ``addr=<addr>`` 1871 Set the IP address spice is listening on. Default is any 1872 address. 1873 1874 ``ipv4``; \ ``ipv6``; \ ``unix`` 1875 Force using the specified IP version. 1876 1877 ``password=<secret>`` 1878 Set the password you need to authenticate. 1879 1880 ``sasl`` 1881 Require that the client use SASL to authenticate with the spice. 1882 The exact choice of authentication method used is controlled 1883 from the system / user's SASL configuration file for the 'qemu' 1884 service. This is typically found in /etc/sasl2/qemu.conf. If 1885 running QEMU as an unprivileged user, an environment variable 1886 SASL\_CONF\_PATH can be used to make it search alternate 1887 locations for the service config. While some SASL auth methods 1888 can also provide data encryption (eg GSSAPI), it is recommended 1889 that SASL always be combined with the 'tls' and 'x509' settings 1890 to enable use of SSL and server certificates. This ensures a 1891 data encryption preventing compromise of authentication 1892 credentials. 1893 1894 ``disable-ticketing`` 1895 Allow client connects without authentication. 1896 1897 ``disable-copy-paste`` 1898 Disable copy paste between the client and the guest. 1899 1900 ``disable-agent-file-xfer`` 1901 Disable spice-vdagent based file-xfer between the client and the 1902 guest. 1903 1904 ``tls-port=<nr>`` 1905 Set the TCP port spice is listening on for encrypted channels. 1906 1907 ``x509-dir=<dir>`` 1908 Set the x509 file directory. Expects same filenames as -vnc 1909 $display,x509=$dir 1910 1911 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>`` 1912 The x509 file names can also be configured individually. 1913 1914 ``tls-ciphers=<list>`` 1915 Specify which ciphers to use. 1916 1917 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]`` 1918 Force specific channel to be used with or without TLS 1919 encryption. The options can be specified multiple times to 1920 configure multiple channels. The special name "default" can be 1921 used to set the default mode. For channels which are not 1922 explicitly forced into one mode the spice client is allowed to 1923 pick tls/plaintext as he pleases. 1924 1925 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]`` 1926 Configure image compression (lossless). Default is auto\_glz. 1927 1928 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]`` 1929 Configure wan image compression (lossy for slow links). Default 1930 is auto. 1931 1932 ``streaming-video=[off|all|filter]`` 1933 Configure video stream detection. Default is off. 1934 1935 ``agent-mouse=[on|off]`` 1936 Enable/disable passing mouse events via vdagent. Default is on. 1937 1938 ``playback-compression=[on|off]`` 1939 Enable/disable audio stream compression (using celt 0.5.1). 1940 Default is on. 1941 1942 ``seamless-migration=[on|off]`` 1943 Enable/disable spice seamless migration. Default is off. 1944 1945 ``gl=[on|off]`` 1946 Enable/disable OpenGL context. Default is off. 1947 1948 ``rendernode=<file>`` 1949 DRM render node for OpenGL rendering. If not specified, it will 1950 pick the first available. (Since 2.9) 1951ERST 1952 1953DEF("portrait", 0, QEMU_OPTION_portrait, 1954 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n", 1955 QEMU_ARCH_ALL) 1956SRST 1957``-portrait`` 1958 Rotate graphical output 90 deg left (only PXA LCD). 1959ERST 1960 1961DEF("rotate", HAS_ARG, QEMU_OPTION_rotate, 1962 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n", 1963 QEMU_ARCH_ALL) 1964SRST 1965``-rotate deg`` 1966 Rotate graphical output some deg left (only PXA LCD). 1967ERST 1968 1969DEF("vga", HAS_ARG, QEMU_OPTION_vga, 1970 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n" 1971 " select video card type\n", QEMU_ARCH_ALL) 1972SRST 1973``-vga type`` 1974 Select type of VGA card to emulate. Valid values for type are 1975 1976 ``cirrus`` 1977 Cirrus Logic GD5446 Video card. All Windows versions starting 1978 from Windows 95 should recognize and use this graphic card. For 1979 optimal performances, use 16 bit color depth in the guest and 1980 the host OS. (This card was the default before QEMU 2.2) 1981 1982 ``std`` 1983 Standard VGA card with Bochs VBE extensions. If your guest OS 1984 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if 1985 you want to use high resolution modes (>= 1280x1024x16) then you 1986 should use this option. (This card is the default since QEMU 1987 2.2) 1988 1989 ``vmware`` 1990 VMWare SVGA-II compatible adapter. Use it if you have 1991 sufficiently recent XFree86/XOrg server or Windows guest with a 1992 driver for this card. 1993 1994 ``qxl`` 1995 QXL paravirtual graphic card. It is VGA compatible (including 1996 VESA 2.0 VBE support). Works best with qxl guest drivers 1997 installed though. Recommended choice when using the spice 1998 protocol. 1999 2000 ``tcx`` 2001 (sun4m only) Sun TCX framebuffer. This is the default 2002 framebuffer for sun4m machines and offers both 8-bit and 24-bit 2003 colour depths at a fixed resolution of 1024x768. 2004 2005 ``cg3`` 2006 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit 2007 framebuffer for sun4m machines available in both 1024x768 2008 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people 2009 wishing to run older Solaris versions. 2010 2011 ``virtio`` 2012 Virtio VGA card. 2013 2014 ``none`` 2015 Disable VGA card. 2016ERST 2017 2018DEF("full-screen", 0, QEMU_OPTION_full_screen, 2019 "-full-screen start in full screen\n", QEMU_ARCH_ALL) 2020SRST 2021``-full-screen`` 2022 Start in full screen. 2023ERST 2024 2025DEF("g", HAS_ARG, QEMU_OPTION_g , 2026 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n", 2027 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K) 2028SRST 2029``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]`` 2030 Set the initial graphical resolution and depth (PPC, SPARC only). 2031 2032 For PPC the default is 800x600x32. 2033 2034 For SPARC with the TCX graphics device, the default is 1024x768x8 2035 with the option of 1024x768x24. For cgthree, the default is 2036 1024x768x8 with the option of 1152x900x8 for people who wish to use 2037 OBP. 2038ERST 2039 2040DEF("vnc", HAS_ARG, QEMU_OPTION_vnc , 2041 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL) 2042SRST 2043``-vnc display[,option[,option[,...]]]`` 2044 Normally, if QEMU is compiled with graphical window support, it 2045 displays output such as guest graphics, guest console, and the QEMU 2046 monitor in a window. With this option, you can have QEMU listen on 2047 VNC display display and redirect the VGA display over the VNC 2048 session. It is very useful to enable the usb tablet device when 2049 using this option (option ``-device usb-tablet``). When using the 2050 VNC display, you must use the ``-k`` parameter to set the keyboard 2051 layout if you are not using en-us. Valid syntax for the display is 2052 2053 ``to=L`` 2054 With this option, QEMU will try next available VNC displays, 2055 until the number L, if the origianlly defined "-vnc display" is 2056 not available, e.g. port 5900+display is already used by another 2057 application. By default, to=0. 2058 2059 ``host:d`` 2060 TCP connections will only be allowed from host on display d. By 2061 convention the TCP port is 5900+d. Optionally, host can be 2062 omitted in which case the server will accept connections from 2063 any host. 2064 2065 ``unix:path`` 2066 Connections will be allowed over UNIX domain sockets where path 2067 is the location of a unix socket to listen for connections on. 2068 2069 ``none`` 2070 VNC is initialized but not started. The monitor ``change`` 2071 command can be used to later start the VNC server. 2072 2073 Following the display value there may be one or more option flags 2074 separated by commas. Valid options are 2075 2076 ``reverse`` 2077 Connect to a listening VNC client via a "reverse" connection. 2078 The client is specified by the display. For reverse network 2079 connections (host:d,``reverse``), the d argument is a TCP port 2080 number, not a display number. 2081 2082 ``websocket`` 2083 Opens an additional TCP listening port dedicated to VNC 2084 Websocket connections. If a bare websocket option is given, the 2085 Websocket port is 5700+display. An alternative port can be 2086 specified with the syntax ``websocket``\ =port. 2087 2088 If host is specified connections will only be allowed from this 2089 host. It is possible to control the websocket listen address 2090 independently, using the syntax ``websocket``\ =host:port. 2091 2092 If no TLS credentials are provided, the websocket connection 2093 runs in unencrypted mode. If TLS credentials are provided, the 2094 websocket connection requires encrypted client connections. 2095 2096 ``password`` 2097 Require that password based authentication is used for client 2098 connections. 2099 2100 The password must be set separately using the ``set_password`` 2101 command in the :ref:`pcsys_005fmonitor`. The 2102 syntax to change your password is: 2103 ``set_password <protocol> <password>`` where <protocol> could be 2104 either "vnc" or "spice". 2105 2106 If you would like to change <protocol> password expiration, you 2107 should use ``expire_password <protocol> <expiration-time>`` 2108 where expiration time could be one of the following options: 2109 now, never, +seconds or UNIX time of expiration, e.g. +60 to 2110 make password expire in 60 seconds, or 1335196800 to make 2111 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for 2112 this date and time). 2113 2114 You can also use keywords "now" or "never" for the expiration 2115 time to allow <protocol> password to expire immediately or never 2116 expire. 2117 2118 ``tls-creds=ID`` 2119 Provides the ID of a set of TLS credentials to use to secure the 2120 VNC server. They will apply to both the normal VNC server socket 2121 and the websocket socket (if enabled). Setting TLS credentials 2122 will cause the VNC server socket to enable the VeNCrypt auth 2123 mechanism. The credentials should have been previously created 2124 using the ``-object tls-creds`` argument. 2125 2126 ``tls-authz=ID`` 2127 Provides the ID of the QAuthZ authorization object against which 2128 the client's x509 distinguished name will validated. This object 2129 is only resolved at time of use, so can be deleted and recreated 2130 on the fly while the VNC server is active. If missing, it will 2131 default to denying access. 2132 2133 ``sasl`` 2134 Require that the client use SASL to authenticate with the VNC 2135 server. The exact choice of authentication method used is 2136 controlled from the system / user's SASL configuration file for 2137 the 'qemu' service. This is typically found in 2138 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, 2139 an environment variable SASL\_CONF\_PATH can be used to make it 2140 search alternate locations for the service config. While some 2141 SASL auth methods can also provide data encryption (eg GSSAPI), 2142 it is recommended that SASL always be combined with the 'tls' 2143 and 'x509' settings to enable use of SSL and server 2144 certificates. This ensures a data encryption preventing 2145 compromise of authentication credentials. See the 2146 :ref:`vnc_005fsecurity` section for details on 2147 using SASL authentication. 2148 2149 ``sasl-authz=ID`` 2150 Provides the ID of the QAuthZ authorization object against which 2151 the client's SASL username will validated. This object is only 2152 resolved at time of use, so can be deleted and recreated on the 2153 fly while the VNC server is active. If missing, it will default 2154 to denying access. 2155 2156 ``acl`` 2157 Legacy method for enabling authorization of clients against the 2158 x509 distinguished name and SASL username. It results in the 2159 creation of two ``authz-list`` objects with IDs of 2160 ``vnc.username`` and ``vnc.x509dname``. The rules for these 2161 objects must be configured with the HMP ACL commands. 2162 2163 This option is deprecated and should no longer be used. The new 2164 ``sasl-authz`` and ``tls-authz`` options are a replacement. 2165 2166 ``lossy`` 2167 Enable lossy compression methods (gradient, JPEG, ...). If this 2168 option is set, VNC client may receive lossy framebuffer updates 2169 depending on its encoding settings. Enabling this option can 2170 save a lot of bandwidth at the expense of quality. 2171 2172 ``non-adaptive`` 2173 Disable adaptive encodings. Adaptive encodings are enabled by 2174 default. An adaptive encoding will try to detect frequently 2175 updated screen regions, and send updates in these regions using 2176 a lossy encoding (like JPEG). This can be really helpful to save 2177 bandwidth when playing videos. Disabling adaptive encodings 2178 restores the original static behavior of encodings like Tight. 2179 2180 ``share=[allow-exclusive|force-shared|ignore]`` 2181 Set display sharing policy. 'allow-exclusive' allows clients to 2182 ask for exclusive access. As suggested by the rfb spec this is 2183 implemented by dropping other connections. Connecting multiple 2184 clients in parallel requires all clients asking for a shared 2185 session (vncviewer: -shared switch). This is the default. 2186 'force-shared' disables exclusive client access. Useful for 2187 shared desktop sessions, where you don't want someone forgetting 2188 specify -shared disconnect everybody else. 'ignore' completely 2189 ignores the shared flag and allows everybody connect 2190 unconditionally. Doesn't conform to the rfb spec but is 2191 traditional QEMU behavior. 2192 2193 ``key-delay-ms`` 2194 Set keyboard delay, for key down and key up events, in 2195 milliseconds. Default is 10. Keyboards are low-bandwidth 2196 devices, so this slowdown can help the device and guest to keep 2197 up and not lose events in case events are arriving in bulk. 2198 Possible causes for the latter are flaky network connections, or 2199 scripts for automated testing. 2200 2201 ``audiodev=audiodev`` 2202 Use the specified audiodev when the VNC client requests audio 2203 transmission. When not using an -audiodev argument, this option 2204 must be omitted, otherwise is must be present and specify a 2205 valid audiodev. 2206ERST 2207 2208ARCHHEADING(, QEMU_ARCH_I386) 2209 2210ARCHHEADING(i386 target only:, QEMU_ARCH_I386) 2211 2212DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack, 2213 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n", 2214 QEMU_ARCH_I386) 2215SRST 2216``-win2k-hack`` 2217 Use it when installing Windows 2000 to avoid a disk full bug. After 2218 Windows 2000 is installed, you no longer need this option (this 2219 option slows down the IDE transfers). 2220ERST 2221 2222DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk, 2223 "-no-fd-bootchk disable boot signature checking for floppy disks\n", 2224 QEMU_ARCH_I386) 2225SRST 2226``-no-fd-bootchk`` 2227 Disable boot signature checking for floppy disks in BIOS. May be 2228 needed to boot from old floppy disks. 2229ERST 2230 2231DEF("no-acpi", 0, QEMU_OPTION_no_acpi, 2232 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2233SRST 2234``-no-acpi`` 2235 Disable ACPI (Advanced Configuration and Power Interface) support. 2236 Use it if your guest OS complains about ACPI problems (PC target 2237 machine only). 2238ERST 2239 2240DEF("no-hpet", 0, QEMU_OPTION_no_hpet, 2241 "-no-hpet disable HPET\n", QEMU_ARCH_I386) 2242SRST 2243``-no-hpet`` 2244 Disable HPET support. 2245ERST 2246 2247DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable, 2248 "-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n][,asl_compiler_id=str][,asl_compiler_rev=n][,{data|file}=file1[:file2]...]\n" 2249 " ACPI table description\n", QEMU_ARCH_I386) 2250SRST 2251``-acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n] [,asl_compiler_id=str][,asl_compiler_rev=n][,data=file1[:file2]...]`` 2252 Add ACPI table with specified header fields and context from 2253 specified files. For file=, take whole ACPI table from the specified 2254 files, including all ACPI headers (possible overridden by other 2255 options). For data=, only data portion of the table is used, all 2256 header information is specified in the command line. If a SLIC table 2257 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id 2258 fields will override the same in the RSDT and the FADT (a.k.a. 2259 FACP), in order to ensure the field matches required by the 2260 Microsoft SLIC spec and the ACPI spec. 2261ERST 2262 2263DEF("smbios", HAS_ARG, QEMU_OPTION_smbios, 2264 "-smbios file=binary\n" 2265 " load SMBIOS entry from binary file\n" 2266 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n" 2267 " [,uefi=on|off]\n" 2268 " specify SMBIOS type 0 fields\n" 2269 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2270 " [,uuid=uuid][,sku=str][,family=str]\n" 2271 " specify SMBIOS type 1 fields\n" 2272 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2273 " [,asset=str][,location=str]\n" 2274 " specify SMBIOS type 2 fields\n" 2275 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n" 2276 " [,sku=str]\n" 2277 " specify SMBIOS type 3 fields\n" 2278 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n" 2279 " [,asset=str][,part=str]\n" 2280 " specify SMBIOS type 4 fields\n" 2281 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n" 2282 " [,asset=str][,part=str][,speed=%d]\n" 2283 " specify SMBIOS type 17 fields\n", 2284 QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2285SRST 2286``-smbios file=binary`` 2287 Load SMBIOS entry from binary file. 2288 2289``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]`` 2290 Specify SMBIOS type 0 fields 2291 2292``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]`` 2293 Specify SMBIOS type 1 fields 2294 2295``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]`` 2296 Specify SMBIOS type 2 fields 2297 2298``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]`` 2299 Specify SMBIOS type 3 fields 2300 2301``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]`` 2302 Specify SMBIOS type 4 fields 2303 2304``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]`` 2305 Specify SMBIOS type 17 fields 2306ERST 2307 2308DEFHEADING() 2309 2310DEFHEADING(Network options:) 2311 2312DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, 2313#ifdef CONFIG_SLIRP 2314 "-netdev user,id=str[,ipv4[=on|off]][,net=addr[/mask]][,host=addr]\n" 2315 " [,ipv6[=on|off]][,ipv6-net=addr[/int]][,ipv6-host=addr]\n" 2316 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n" 2317 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n" 2318 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]" 2319#ifndef _WIN32 2320 "[,smb=dir[,smbserver=addr]]\n" 2321#endif 2322 " configure a user mode network backend with ID 'str',\n" 2323 " its DHCP server and optional services\n" 2324#endif 2325#ifdef _WIN32 2326 "-netdev tap,id=str,ifname=name\n" 2327 " configure a host TAP network backend with ID 'str'\n" 2328#else 2329 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n" 2330 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" 2331 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" 2332 " [,poll-us=n]\n" 2333 " configure a host TAP network backend with ID 'str'\n" 2334 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2335 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n" 2336 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n" 2337 " to deconfigure it\n" 2338 " use '[down]script=no' to disable script execution\n" 2339 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n" 2340 " configure it\n" 2341 " use 'fd=h' to connect to an already opened TAP interface\n" 2342 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n" 2343 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n" 2344 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n" 2345 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" 2346 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" 2347 " use vhost=on to enable experimental in kernel accelerator\n" 2348 " (only has effect for virtio guests which use MSIX)\n" 2349 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" 2350 " use 'vhostfd=h' to connect to an already opened vhost net device\n" 2351 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n" 2352 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n" 2353 " use 'poll-us=n' to speciy the maximum number of microseconds that could be\n" 2354 " spent on busy polling for vhost net\n" 2355 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n" 2356 " configure a host TAP network backend with ID 'str' that is\n" 2357 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2358 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n" 2359#endif 2360#ifdef __linux__ 2361 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n" 2362 " [,rxsession=rxsession],txsession=txsession[,ipv6=on/off][,udp=on/off]\n" 2363 " [,cookie64=on/off][,counter][,pincounter][,txcookie=txcookie]\n" 2364 " [,rxcookie=rxcookie][,offset=offset]\n" 2365 " configure a network backend with ID 'str' connected to\n" 2366 " an Ethernet over L2TPv3 pseudowire.\n" 2367 " Linux kernel 3.3+ as well as most routers can talk\n" 2368 " L2TPv3. This transport allows connecting a VM to a VM,\n" 2369 " VM to a router and even VM to Host. It is a nearly-universal\n" 2370 " standard (RFC3931). Note - this implementation uses static\n" 2371 " pre-configured tunnels (same as the Linux kernel).\n" 2372 " use 'src=' to specify source address\n" 2373 " use 'dst=' to specify destination address\n" 2374 " use 'udp=on' to specify udp encapsulation\n" 2375 " use 'srcport=' to specify source udp port\n" 2376 " use 'dstport=' to specify destination udp port\n" 2377 " use 'ipv6=on' to force v6\n" 2378 " L2TPv3 uses cookies to prevent misconfiguration as\n" 2379 " well as a weak security measure\n" 2380 " use 'rxcookie=0x012345678' to specify a rxcookie\n" 2381 " use 'txcookie=0x012345678' to specify a txcookie\n" 2382 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n" 2383 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n" 2384 " use 'pincounter=on' to work around broken counter handling in peer\n" 2385 " use 'offset=X' to add an extra offset between header and data\n" 2386#endif 2387 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n" 2388 " configure a network backend to connect to another network\n" 2389 " using a socket connection\n" 2390 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n" 2391 " configure a network backend to connect to a multicast maddr and port\n" 2392 " use 'localaddr=addr' to specify the host address to send packets from\n" 2393 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n" 2394 " configure a network backend to connect to another network\n" 2395 " using an UDP tunnel\n" 2396#ifdef CONFIG_VDE 2397 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n" 2398 " configure a network backend to connect to port 'n' of a vde switch\n" 2399 " running on host and listening for incoming connections on 'socketpath'.\n" 2400 " Use group 'groupname' and mode 'octalmode' to change default\n" 2401 " ownership and permissions for communication port.\n" 2402#endif 2403#ifdef CONFIG_NETMAP 2404 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n" 2405 " attach to the existing netmap-enabled network interface 'name', or to a\n" 2406 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n" 2407 " netmap device, defaults to '/dev/netmap')\n" 2408#endif 2409#ifdef CONFIG_POSIX 2410 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" 2411 " configure a vhost-user network, backed by a chardev 'dev'\n" 2412#endif 2413 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n" 2414 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL) 2415DEF("nic", HAS_ARG, QEMU_OPTION_nic, 2416 "-nic [tap|bridge|" 2417#ifdef CONFIG_SLIRP 2418 "user|" 2419#endif 2420#ifdef __linux__ 2421 "l2tpv3|" 2422#endif 2423#ifdef CONFIG_VDE 2424 "vde|" 2425#endif 2426#ifdef CONFIG_NETMAP 2427 "netmap|" 2428#endif 2429#ifdef CONFIG_POSIX 2430 "vhost-user|" 2431#endif 2432 "socket][,option][,...][mac=macaddr]\n" 2433 " initialize an on-board / default host NIC (using MAC address\n" 2434 " macaddr) and connect it to the given host network backend\n" 2435 "-nic none use it alone to have zero network devices (the default is to\n" 2436 " provided a 'user' network connection)\n", 2437 QEMU_ARCH_ALL) 2438DEF("net", HAS_ARG, QEMU_OPTION_net, 2439 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" 2440 " configure or create an on-board (or machine default) NIC and\n" 2441 " connect it to hub 0 (please use -nic unless you need a hub)\n" 2442 "-net [" 2443#ifdef CONFIG_SLIRP 2444 "user|" 2445#endif 2446 "tap|" 2447 "bridge|" 2448#ifdef CONFIG_VDE 2449 "vde|" 2450#endif 2451#ifdef CONFIG_NETMAP 2452 "netmap|" 2453#endif 2454 "socket][,option][,option][,...]\n" 2455 " old way to initialize a host network interface\n" 2456 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL) 2457SRST 2458``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]`` 2459 This option is a shortcut for configuring both the on-board 2460 (default) guest NIC hardware and the host network backend in one go. 2461 The host backend options are the same as with the corresponding 2462 ``-netdev`` options below. The guest NIC model can be set with 2463 ``model=modelname``. Use ``model=help`` to list the available device 2464 types. The hardware MAC address can be set with ``mac=macaddr``. 2465 2466 The following two example do exactly the same, to show how ``-nic`` 2467 can be used to shorten the command line length: 2468 2469 .. parsed-literal:: 2470 2471 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32 2472 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32 2473 2474``-nic none`` 2475 Indicate that no network devices should be configured. It is used to 2476 override the default configuration (default NIC with "user" host 2477 network backend) which is activated if no other networking options 2478 are provided. 2479 2480``-netdev user,id=id[,option][,option][,...]`` 2481 Configure user mode host network backend which requires no 2482 administrator privilege to run. Valid options are: 2483 2484 ``id=id`` 2485 Assign symbolic name for use in monitor commands. 2486 2487 ``ipv4=on|off and ipv6=on|off`` 2488 Specify that either IPv4 or IPv6 must be enabled. If neither is 2489 specified both protocols are enabled. 2490 2491 ``net=addr[/mask]`` 2492 Set IP network address the guest will see. Optionally specify 2493 the netmask, either in the form a.b.c.d or as number of valid 2494 top-most bits. Default is 10.0.2.0/24. 2495 2496 ``host=addr`` 2497 Specify the guest-visible address of the host. Default is the 2498 2nd IP in the guest network, i.e. x.x.x.2. 2499 2500 ``ipv6-net=addr[/int]`` 2501 Set IPv6 network address the guest will see (default is 2502 fec0::/64). The network prefix is given in the usual hexadecimal 2503 IPv6 address notation. The prefix size is optional, and is given 2504 as the number of valid top-most bits (default is 64). 2505 2506 ``ipv6-host=addr`` 2507 Specify the guest-visible IPv6 address of the host. Default is 2508 the 2nd IPv6 in the guest network, i.e. xxxx::2. 2509 2510 ``restrict=on|off`` 2511 If this option is enabled, the guest will be isolated, i.e. it 2512 will not be able to contact the host and no guest IP packets 2513 will be routed over the host to the outside. This option does 2514 not affect any explicitly set forwarding rules. 2515 2516 ``hostname=name`` 2517 Specifies the client hostname reported by the built-in DHCP 2518 server. 2519 2520 ``dhcpstart=addr`` 2521 Specify the first of the 16 IPs the built-in DHCP server can 2522 assign. Default is the 15th to 31st IP in the guest network, 2523 i.e. x.x.x.15 to x.x.x.31. 2524 2525 ``dns=addr`` 2526 Specify the guest-visible address of the virtual nameserver. The 2527 address must be different from the host address. Default is the 2528 3rd IP in the guest network, i.e. x.x.x.3. 2529 2530 ``ipv6-dns=addr`` 2531 Specify the guest-visible address of the IPv6 virtual 2532 nameserver. The address must be different from the host address. 2533 Default is the 3rd IP in the guest network, i.e. xxxx::3. 2534 2535 ``dnssearch=domain`` 2536 Provides an entry for the domain-search list sent by the 2537 built-in DHCP server. More than one domain suffix can be 2538 transmitted by specifying this option multiple times. If 2539 supported, this will cause the guest to automatically try to 2540 append the given domain suffix(es) in case a domain name can not 2541 be resolved. 2542 2543 Example: 2544 2545 .. parsed-literal:: 2546 2547 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org 2548 2549 ``domainname=domain`` 2550 Specifies the client domain name reported by the built-in DHCP 2551 server. 2552 2553 ``tftp=dir`` 2554 When using the user mode network stack, activate a built-in TFTP 2555 server. The files in dir will be exposed as the root of a TFTP 2556 server. The TFTP client on the guest must be configured in 2557 binary mode (use the command ``bin`` of the Unix TFTP client). 2558 2559 ``tftp-server-name=name`` 2560 In BOOTP reply, broadcast name as the "TFTP server name" 2561 (RFC2132 option 66). This can be used to advise the guest to 2562 load boot files or configurations from a different server than 2563 the host address. 2564 2565 ``bootfile=file`` 2566 When using the user mode network stack, broadcast file as the 2567 BOOTP filename. In conjunction with ``tftp``, this can be used 2568 to network boot a guest from a local directory. 2569 2570 Example (using pxelinux): 2571 2572 .. parsed-literal:: 2573 2574 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \ 2575 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0 2576 2577 ``smb=dir[,smbserver=addr]`` 2578 When using the user mode network stack, activate a built-in SMB 2579 server so that Windows OSes can access to the host files in 2580 ``dir`` transparently. The IP address of the SMB server can be 2581 set to addr. By default the 4th IP in the guest network is used, 2582 i.e. x.x.x.4. 2583 2584 In the guest Windows OS, the line: 2585 2586 :: 2587 2588 10.0.2.4 smbserver 2589 2590 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows 2591 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows 2592 NT/2000). 2593 2594 Then ``dir`` can be accessed in ``\\smbserver\qemu``. 2595 2596 Note that a SAMBA server must be installed on the host OS. 2597 2598 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport`` 2599 Redirect incoming TCP or UDP connections to the host port 2600 hostport to the guest IP address guestaddr on guest port 2601 guestport. If guestaddr is not specified, its value is x.x.x.15 2602 (default first address given by the built-in DHCP server). By 2603 specifying hostaddr, the rule can be bound to a specific host 2604 interface. If no connection type is set, TCP is used. This 2605 option can be given multiple times. 2606 2607 For example, to redirect host X11 connection from screen 1 to 2608 guest screen 0, use the following: 2609 2610 .. parsed-literal:: 2611 2612 # on the host 2613 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000 2614 # this host xterm should open in the guest X11 server 2615 xterm -display :1 2616 2617 To redirect telnet connections from host port 5555 to telnet 2618 port on the guest, use the following: 2619 2620 .. parsed-literal:: 2621 2622 # on the host 2623 |qemu_system| -nic user,hostfwd=tcp::5555-:23 2624 telnet localhost 5555 2625 2626 Then when you use on the host ``telnet localhost 5555``, you 2627 connect to the guest telnet server. 2628 2629 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command`` 2630 Forward guest TCP connections to the IP address server on port 2631 port to the character device dev or to a program executed by 2632 cmd:command which gets spawned for each connection. This option 2633 can be given multiple times. 2634 2635 You can either use a chardev directly and have that one used 2636 throughout QEMU's lifetime, like in the following example: 2637 2638 .. parsed-literal:: 2639 2640 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever 2641 # the guest accesses it 2642 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 2643 2644 Or you can execute a command on every TCP connection established 2645 by the guest, so that QEMU behaves similar to an inetd process 2646 for that virtual server: 2647 2648 .. parsed-literal:: 2649 2650 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234 2651 # and connect the TCP stream to its stdin/stdout 2652 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321' 2653 2654``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]`` 2655 Configure a host TAP network backend with ID id. 2656 2657 Use the network script file to configure it and the network script 2658 dfile to deconfigure it. If name is not provided, the OS 2659 automatically provides one. The default network configure script is 2660 ``/etc/qemu-ifup`` and the default network deconfigure script is 2661 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to 2662 disable script execution. 2663 2664 If running QEMU as an unprivileged user, use the network helper 2665 helper to configure the TAP interface and attach it to the bridge. 2666 The default network helper executable is 2667 ``/path/to/qemu-bridge-helper`` and the default bridge device is 2668 ``br0``. 2669 2670 ``fd``\ =h can be used to specify the handle of an already opened 2671 host TAP interface. 2672 2673 Examples: 2674 2675 .. parsed-literal:: 2676 2677 #launch a QEMU instance with the default network script 2678 |qemu_system| linux.img -nic tap 2679 2680 .. parsed-literal:: 2681 2682 #launch a QEMU instance with two NICs, each one connected 2683 #to a TAP device 2684 |qemu_system| linux.img \ 2685 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \ 2686 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1 2687 2688 .. parsed-literal:: 2689 2690 #launch a QEMU instance with the default network helper to 2691 #connect a TAP device to bridge br0 2692 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \ 2693 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper" 2694 2695``-netdev bridge,id=id[,br=bridge][,helper=helper]`` 2696 Connect a host TAP network interface to a host bridge device. 2697 2698 Use the network helper helper to configure the TAP interface and 2699 attach it to the bridge. The default network helper executable is 2700 ``/path/to/qemu-bridge-helper`` and the default bridge device is 2701 ``br0``. 2702 2703 Examples: 2704 2705 .. parsed-literal:: 2706 2707 #launch a QEMU instance with the default network helper to 2708 #connect a TAP device to bridge br0 2709 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1 2710 2711 .. parsed-literal:: 2712 2713 #launch a QEMU instance with the default network helper to 2714 #connect a TAP device to bridge qemubr0 2715 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1 2716 2717``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]`` 2718 This host network backend can be used to connect the guest's network 2719 to another QEMU virtual machine using a TCP socket connection. If 2720 ``listen`` is specified, QEMU waits for incoming connections on port 2721 (host is optional). ``connect`` is used to connect to another QEMU 2722 instance using the ``listen`` option. ``fd``\ =h specifies an 2723 already opened TCP socket. 2724 2725 Example: 2726 2727 .. parsed-literal:: 2728 2729 # launch a first QEMU instance 2730 |qemu_system| linux.img \ 2731 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \ 2732 -netdev socket,id=n1,listen=:1234 2733 # connect the network of this instance to the network of the first instance 2734 |qemu_system| linux.img \ 2735 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \ 2736 -netdev socket,id=n2,connect=127.0.0.1:1234 2737 2738``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]`` 2739 Configure a socket host network backend to share the guest's network 2740 traffic with another QEMU virtual machines using a UDP multicast 2741 socket, effectively making a bus for every QEMU with same multicast 2742 address maddr and port. NOTES: 2743 2744 1. Several QEMU can be running on different hosts and share same bus 2745 (assuming correct multicast setup for these hosts). 2746 2747 2. mcast support is compatible with User Mode Linux (argument 2748 ``ethN=mcast``), see http://user-mode-linux.sf.net. 2749 2750 3. Use ``fd=h`` to specify an already opened UDP multicast socket. 2751 2752 Example: 2753 2754 .. parsed-literal:: 2755 2756 # launch one QEMU instance 2757 |qemu_system| linux.img \ 2758 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \ 2759 -netdev socket,id=n1,mcast=230.0.0.1:1234 2760 # launch another QEMU instance on same "bus" 2761 |qemu_system| linux.img \ 2762 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \ 2763 -netdev socket,id=n2,mcast=230.0.0.1:1234 2764 # launch yet another QEMU instance on same "bus" 2765 |qemu_system| linux.img \ 2766 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \ 2767 -netdev socket,id=n3,mcast=230.0.0.1:1234 2768 2769 Example (User Mode Linux compat.): 2770 2771 .. parsed-literal:: 2772 2773 # launch QEMU instance (note mcast address selected is UML's default) 2774 |qemu_system| linux.img \ 2775 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \ 2776 -netdev socket,id=n1,mcast=239.192.168.1:1102 2777 # launch UML 2778 /path/to/linux ubd0=/path/to/root_fs eth0=mcast 2779 2780 Example (send packets from host's 1.2.3.4): 2781 2782 .. parsed-literal:: 2783 2784 |qemu_system| linux.img \ 2785 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \ 2786 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4 2787 2788``-netdev l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6][,udp][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]`` 2789 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931) 2790 is a popular protocol to transport Ethernet (and other Layer 2) data 2791 frames between two systems. It is present in routers, firewalls and 2792 the Linux kernel (from version 3.3 onwards). 2793 2794 This transport allows a VM to communicate to another VM, router or 2795 firewall directly. 2796 2797 ``src=srcaddr`` 2798 source address (mandatory) 2799 2800 ``dst=dstaddr`` 2801 destination address (mandatory) 2802 2803 ``udp`` 2804 select udp encapsulation (default is ip). 2805 2806 ``srcport=srcport`` 2807 source udp port. 2808 2809 ``dstport=dstport`` 2810 destination udp port. 2811 2812 ``ipv6`` 2813 force v6, otherwise defaults to v4. 2814 2815 ``rxcookie=rxcookie``; \ ``txcookie=txcookie`` 2816 Cookies are a weak form of security in the l2tpv3 specification. 2817 Their function is mostly to prevent misconfiguration. By default 2818 they are 32 bit. 2819 2820 ``cookie64`` 2821 Set cookie size to 64 bit instead of the default 32 2822 2823 ``counter=off`` 2824 Force a 'cut-down' L2TPv3 with no counter as in 2825 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00 2826 2827 ``pincounter=on`` 2828 Work around broken counter handling in peer. This may also help 2829 on networks which have packet reorder. 2830 2831 ``offset=offset`` 2832 Add an extra offset between header and data 2833 2834 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to 2835 the bridge br-lan on the remote Linux host 1.2.3.4: 2836 2837 .. parsed-literal:: 2838 2839 # Setup tunnel on linux host using raw ip as encapsulation 2840 # on 1.2.3.4 2841 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \ 2842 encap udp udp_sport 16384 udp_dport 16384 2843 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \ 2844 0xFFFFFFFF peer_session_id 0xFFFFFFFF 2845 ifconfig vmtunnel0 mtu 1500 2846 ifconfig vmtunnel0 up 2847 brctl addif br-lan vmtunnel0 2848 2849 2850 # on 4.3.2.1 2851 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter 2852 2853 |qemu_system| linux.img -device e1000,netdev=n1 \ 2854 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter 2855 2856``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]`` 2857 Configure VDE backend to connect to PORT n of a vde switch running 2858 on host and listening for incoming connections on socketpath. Use 2859 GROUP groupname and MODE octalmode to change default ownership and 2860 permissions for communication port. This option is only available if 2861 QEMU has been compiled with vde support enabled. 2862 2863 Example: 2864 2865 .. parsed-literal:: 2866 2867 # launch vde switch 2868 vde_switch -F -sock /tmp/myswitch 2869 # launch QEMU instance 2870 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch 2871 2872``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]`` 2873 Establish a vhost-user netdev, backed by a chardev id. The chardev 2874 should be a unix domain socket backed one. The vhost-user uses a 2875 specifically defined protocol to pass vhost ioctl replacement 2876 messages to an application on the other end of the socket. On 2877 non-MSIX guests, the feature can be forced with vhostforce. Use 2878 'queues=n' to specify the number of queues to be created for 2879 multiqueue vhost-user. 2880 2881 Example: 2882 2883 :: 2884 2885 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \ 2886 -numa node,memdev=mem \ 2887 -chardev socket,id=chr0,path=/path/to/socket \ 2888 -netdev type=vhost-user,id=net0,chardev=chr0 \ 2889 -device virtio-net-pci,netdev=net0 2890 2891``-netdev hubport,id=id,hubid=hubid[,netdev=nd]`` 2892 Create a hub port on the emulated hub with ID hubid. 2893 2894 The hubport netdev lets you connect a NIC to a QEMU emulated hub 2895 instead of a single netdev. Alternatively, you can also connect the 2896 hubport to another netdev with ID nd by using the ``netdev=nd`` 2897 option. 2898 2899``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]`` 2900 Legacy option to configure or create an on-board (or machine 2901 default) Network Interface Card(NIC) and connect it either to the 2902 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd. 2903 If model is omitted, then the default NIC model associated with the 2904 machine type is used. Note that the default NIC model may change in 2905 future QEMU releases, so it is highly recommended to always specify 2906 a model. Optionally, the MAC address can be changed to mac, the 2907 device address set to addr (PCI cards only), and a name can be 2908 assigned for use in monitor commands. Optionally, for PCI cards, you 2909 can specify the number v of MSI-X vectors that the card should have; 2910 this option currently only affects virtio cards; set v = 0 to 2911 disable MSI-X. If no ``-net`` option is specified, a single NIC is 2912 created. QEMU can emulate several different models of network card. 2913 Use ``-net nic,model=help`` for a list of available devices for your 2914 target. 2915 2916``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]`` 2917 Configure a host network backend (with the options corresponding to 2918 the same ``-netdev`` option) and connect it to the emulated hub 0 2919 (the default hub). Use name to specify the name of the hub port. 2920ERST 2921 2922DEFHEADING() 2923 2924DEFHEADING(Character device options:) 2925 2926DEF("chardev", HAS_ARG, QEMU_OPTION_chardev, 2927 "-chardev help\n" 2928 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2929 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4][,ipv6][,nodelay][,reconnect=seconds]\n" 2930 " [,server][,nowait][,telnet][,websocket][,reconnect=seconds][,mux=on|off]\n" 2931 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n" 2932 "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,websocket][,reconnect=seconds]\n" 2933 " [,mux=on|off][,logfile=PATH][,logappend=on|off] (unix)\n" 2934 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n" 2935 " [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n" 2936 " [,logfile=PATH][,logappend=on|off]\n" 2937 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2938 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n" 2939 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2940 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n" 2941 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2942 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2943#ifdef _WIN32 2944 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2945 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2946#else 2947 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2948 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n" 2949#endif 2950#ifdef CONFIG_BRLAPI 2951 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2952#endif 2953#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ 2954 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) 2955 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2956 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2957#endif 2958#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__) 2959 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2960 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 2961#endif 2962#if defined(CONFIG_SPICE) 2963 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 2964 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 2965#endif 2966 , QEMU_ARCH_ALL 2967) 2968 2969SRST 2970The general form of a character device option is: 2971 2972``-chardev backend,id=id[,mux=on|off][,options]`` 2973 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, 2974 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``, 2975 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``, 2976 ``spicevmc``, ``spiceport``. The specific backend will determine the 2977 applicable options. 2978 2979 Use ``-chardev help`` to print all available chardev backend types. 2980 2981 All devices must have an id, which can be any string up to 127 2982 characters long. It is used to uniquely identify this device in 2983 other command line directives. 2984 2985 A character device may be used in multiplexing mode by multiple 2986 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is 2987 a "1:N" device, and here the "1" end is your specified chardev 2988 backend, and the "N" end is the various parts of QEMU that can talk 2989 to a chardev. If you create a chardev with ``id=myid`` and 2990 ``mux=on``, QEMU will create a multiplexer with your specified ID, 2991 and you can then configure multiple front ends to use that chardev 2992 ID for their input/output. Up to four different front ends can be 2993 connected to a single multiplexed chardev. (Without multiplexing 2994 enabled, a chardev can only be used by a single front end.) For 2995 instance you could use this to allow a single stdio chardev to be 2996 used by two serial ports and the QEMU monitor: 2997 2998 :: 2999 3000 -chardev stdio,mux=on,id=char0 \ 3001 -mon chardev=char0,mode=readline \ 3002 -serial chardev:char0 \ 3003 -serial chardev:char0 3004 3005 You can have more than one multiplexer in a system configuration; 3006 for instance you could have a TCP port multiplexed between UART 0 3007 and UART 1, and stdio multiplexed between the QEMU monitor and a 3008 parallel port: 3009 3010 :: 3011 3012 -chardev stdio,mux=on,id=char0 \ 3013 -mon chardev=char0,mode=readline \ 3014 -parallel chardev:char0 \ 3015 -chardev tcp,...,mux=on,id=char1 \ 3016 -serial chardev:char1 \ 3017 -serial chardev:char1 3018 3019 When you're using a multiplexed character device, some escape 3020 sequences are interpreted in the input. See :ref:`mux_005fkeys`. 3021 3022 Note that some other command line options may implicitly create 3023 multiplexed character backends; for instance ``-serial mon:stdio`` 3024 creates a multiplexed stdio backend connected to the serial port and 3025 the QEMU monitor, and ``-nographic`` also multiplexes the console 3026 and the monitor to stdio. 3027 3028 There is currently no support for multiplexing in the other 3029 direction (where a single QEMU front end takes input and output from 3030 multiple chardevs). 3031 3032 Every backend supports the ``logfile`` option, which supplies the 3033 path to a file to record all data transmitted via the backend. The 3034 ``logappend`` option controls whether the log file will be truncated 3035 or appended to when opened. 3036 3037The available backends are: 3038 3039``-chardev null,id=id`` 3040 A void device. This device will not emit any data, and will drop any 3041 data it receives. The null backend does not take any options. 3042 3043``-chardev socket,id=id[,TCP options or unix options][,server][,nowait][,telnet][,websocket][,reconnect=seconds][,tls-creds=id][,tls-authz=id]`` 3044 Create a two-way stream socket, which can be either a TCP or a unix 3045 socket. A unix socket will be created if ``path`` is specified. 3046 Behaviour is undefined if TCP options are specified for a unix 3047 socket. 3048 3049 ``server`` specifies that the socket shall be a listening socket. 3050 3051 ``nowait`` specifies that QEMU should not block waiting for a client 3052 to connect to a listening socket. 3053 3054 ``telnet`` specifies that traffic on the socket should interpret 3055 telnet escape sequences. 3056 3057 ``websocket`` specifies that the socket uses WebSocket protocol for 3058 communication. 3059 3060 ``reconnect`` sets the timeout for reconnecting on non-server 3061 sockets when the remote end goes away. qemu will delay this many 3062 seconds and then attempt to reconnect. Zero disables reconnecting, 3063 and is the default. 3064 3065 ``tls-creds`` requests enablement of the TLS protocol for 3066 encryption, and specifies the id of the TLS credentials to use for 3067 the handshake. The credentials must be previously created with the 3068 ``-object tls-creds`` argument. 3069 3070 ``tls-auth`` provides the ID of the QAuthZ authorization object 3071 against which the client's x509 distinguished name will be 3072 validated. This object is only resolved at time of use, so can be 3073 deleted and recreated on the fly while the chardev server is active. 3074 If missing, it will default to denying access. 3075 3076 TCP and unix socket options are given below: 3077 3078 ``TCP options: port=port[,host=host][,to=to][,ipv4][,ipv6][,nodelay]`` 3079 ``host`` for a listening socket specifies the local address to 3080 be bound. For a connecting socket species the remote host to 3081 connect to. ``host`` is optional for listening sockets. If not 3082 specified it defaults to ``0.0.0.0``. 3083 3084 ``port`` for a listening socket specifies the local port to be 3085 bound. For a connecting socket specifies the port on the remote 3086 host to connect to. ``port`` can be given as either a port 3087 number or a service name. ``port`` is required. 3088 3089 ``to`` is only relevant to listening sockets. If it is 3090 specified, and ``port`` cannot be bound, QEMU will attempt to 3091 bind to subsequent ports up to and including ``to`` until it 3092 succeeds. ``to`` must be specified as a port number. 3093 3094 ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be 3095 used. If neither is specified the socket may use either 3096 protocol. 3097 3098 ``nodelay`` disables the Nagle algorithm. 3099 3100 ``unix options: path=path`` 3101 ``path`` specifies the local path of the unix socket. ``path`` 3102 is required. 3103 3104``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4][,ipv6]`` 3105 Sends all traffic from the guest to a remote host over UDP. 3106 3107 ``host`` specifies the remote host to connect to. If not specified 3108 it defaults to ``localhost``. 3109 3110 ``port`` specifies the port on the remote host to connect to. 3111 ``port`` is required. 3112 3113 ``localaddr`` specifies the local address to bind to. If not 3114 specified it defaults to ``0.0.0.0``. 3115 3116 ``localport`` specifies the local port to bind to. If not specified 3117 any available local port will be used. 3118 3119 ``ipv4`` and ``ipv6`` specify that either IPv4 or IPv6 must be used. 3120 If neither is specified the device may use either protocol. 3121 3122``-chardev msmouse,id=id`` 3123 Forward QEMU's emulated msmouse events to the guest. ``msmouse`` 3124 does not take any options. 3125 3126``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]`` 3127 Connect to a QEMU text console. ``vc`` may optionally be given a 3128 specific size. 3129 3130 ``width`` and ``height`` specify the width and height respectively 3131 of the console, in pixels. 3132 3133 ``cols`` and ``rows`` specify that the console be sized to fit a 3134 text console with the given dimensions. 3135 3136``-chardev ringbuf,id=id[,size=size]`` 3137 Create a ring buffer with fixed size ``size``. size must be a power 3138 of two and defaults to ``64K``. 3139 3140``-chardev file,id=id,path=path`` 3141 Log all traffic received from the guest to a file. 3142 3143 ``path`` specifies the path of the file to be opened. This file will 3144 be created if it does not already exist, and overwritten if it does. 3145 ``path`` is required. 3146 3147``-chardev pipe,id=id,path=path`` 3148 Create a two-way connection to the guest. The behaviour differs 3149 slightly between Windows hosts and other hosts: 3150 3151 On Windows, a single duplex pipe will be created at 3152 ``\\.pipe\path``. 3153 3154 On other hosts, 2 pipes will be created called ``path.in`` and 3155 ``path.out``. Data written to ``path.in`` will be received by the 3156 guest. Data written by the guest can be read from ``path.out``. QEMU 3157 will not create these fifos, and requires them to be present. 3158 3159 ``path`` forms part of the pipe path as described above. ``path`` is 3160 required. 3161 3162``-chardev console,id=id`` 3163 Send traffic from the guest to QEMU's standard output. ``console`` 3164 does not take any options. 3165 3166 ``console`` is only available on Windows hosts. 3167 3168``-chardev serial,id=id,path=path`` 3169 Send traffic from the guest to a serial device on the host. 3170 3171 On Unix hosts serial will actually accept any tty device, not only 3172 serial lines. 3173 3174 ``path`` specifies the name of the serial device to open. 3175 3176``-chardev pty,id=id`` 3177 Create a new pseudo-terminal on the host and connect to it. ``pty`` 3178 does not take any options. 3179 3180 ``pty`` is not available on Windows hosts. 3181 3182``-chardev stdio,id=id[,signal=on|off]`` 3183 Connect to standard input and standard output of the QEMU process. 3184 3185 ``signal`` controls if signals are enabled on the terminal, that 3186 includes exiting QEMU with the key sequence Control-c. This option 3187 is enabled by default, use ``signal=off`` to disable it. 3188 3189``-chardev braille,id=id`` 3190 Connect to a local BrlAPI server. ``braille`` does not take any 3191 options. 3192 3193``-chardev tty,id=id,path=path`` 3194 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD 3195 and DragonFlyBSD hosts. It is an alias for ``serial``. 3196 3197 ``path`` specifies the path to the tty. ``path`` is required. 3198 3199``-chardev parallel,id=id,path=path`` 3200 \ 3201``-chardev parport,id=id,path=path`` 3202 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD 3203 hosts. 3204 3205 Connect to a local parallel port. 3206 3207 ``path`` specifies the path to the parallel port device. ``path`` is 3208 required. 3209 3210``-chardev spicevmc,id=id,debug=debug,name=name`` 3211 ``spicevmc`` is only available when spice support is built in. 3212 3213 ``debug`` debug level for spicevmc 3214 3215 ``name`` name of spice channel to connect to 3216 3217 Connect to a spice virtual machine channel, such as vdiport. 3218 3219``-chardev spiceport,id=id,debug=debug,name=name`` 3220 ``spiceport`` is only available when spice support is built in. 3221 3222 ``debug`` debug level for spicevmc 3223 3224 ``name`` name of spice port to connect to 3225 3226 Connect to a spice port, allowing a Spice client to handle the 3227 traffic identified by a name (preferably a fqdn). 3228ERST 3229 3230DEFHEADING() 3231 3232#ifdef CONFIG_TPM 3233DEFHEADING(TPM device options:) 3234 3235DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \ 3236 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n" 3237 " use path to provide path to a character device; default is /dev/tpm0\n" 3238 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n" 3239 " not provided it will be searched for in /sys/class/misc/tpm?/device\n" 3240 "-tpmdev emulator,id=id,chardev=dev\n" 3241 " configure the TPM device using chardev backend\n", 3242 QEMU_ARCH_ALL) 3243SRST 3244The general form of a TPM device option is: 3245 3246``-tpmdev backend,id=id[,options]`` 3247 The specific backend type will determine the applicable options. The 3248 ``-tpmdev`` option creates the TPM backend and requires a 3249 ``-device`` option that specifies the TPM frontend interface model. 3250 3251 Use ``-tpmdev help`` to print all available TPM backend types. 3252 3253The available backends are: 3254 3255``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path`` 3256 (Linux-host only) Enable access to the host's TPM using the 3257 passthrough driver. 3258 3259 ``path`` specifies the path to the host's TPM device, i.e., on a 3260 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by 3261 default ``/dev/tpm0`` is used. 3262 3263 ``cancel-path`` specifies the path to the host TPM device's sysfs 3264 entry allowing for cancellation of an ongoing TPM command. 3265 ``cancel-path`` is optional and by default QEMU will search for the 3266 sysfs entry to use. 3267 3268 Some notes about using the host's TPM with the passthrough driver: 3269 3270 The TPM device accessed by the passthrough driver must not be used 3271 by any other application on the host. 3272 3273 Since the host's firmware (BIOS/UEFI) has already initialized the 3274 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize 3275 the TPM again and may therefore not show a TPM-specific menu that 3276 would otherwise allow the user to configure the TPM, e.g., allow the 3277 user to enable/disable or activate/deactivate the TPM. Further, if 3278 TPM ownership is released from within a VM then the host's TPM will 3279 get disabled and deactivated. To enable and activate the TPM again 3280 afterwards, the host has to be rebooted and the user is required to 3281 enter the firmware's menu to enable and activate the TPM. If the TPM 3282 is left disabled and/or deactivated most TPM commands will fail. 3283 3284 To create a passthrough TPM use the following two options: 3285 3286 :: 3287 3288 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0 3289 3290 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by 3291 ``tpmdev=tpm0`` in the device option. 3292 3293``-tpmdev emulator,id=id,chardev=dev`` 3294 (Linux-host only) Enable access to a TPM emulator using Unix domain 3295 socket based chardev backend. 3296 3297 ``chardev`` specifies the unique ID of a character device backend 3298 that provides connection to the software TPM server. 3299 3300 To create a TPM emulator backend device with chardev socket backend: 3301 3302 :: 3303 3304 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0 3305ERST 3306 3307DEFHEADING() 3308 3309#endif 3310 3311DEFHEADING(Linux/Multiboot boot specific:) 3312SRST 3313When using these options, you can use a given Linux or Multiboot kernel 3314without installing it in the disk image. It can be useful for easier 3315testing of various kernels. 3316 3317 3318ERST 3319 3320DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \ 3321 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL) 3322SRST 3323``-kernel bzImage`` 3324 Use bzImage as kernel image. The kernel can be either a Linux kernel 3325 or in multiboot format. 3326ERST 3327 3328DEF("append", HAS_ARG, QEMU_OPTION_append, \ 3329 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL) 3330SRST 3331``-append cmdline`` 3332 Use cmdline as kernel command line 3333ERST 3334 3335DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \ 3336 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL) 3337SRST 3338``-initrd file`` 3339 Use file as initial ram disk. 3340 3341``-initrd "file1 arg=foo,file2"`` 3342 This syntax is only available with multiboot. 3343 3344 Use file1 and file2 as modules and pass arg=foo as parameter to the 3345 first module. 3346ERST 3347 3348DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \ 3349 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL) 3350SRST 3351``-dtb file`` 3352 Use file as a device tree binary (dtb) image and pass it to the 3353 kernel on boot. 3354ERST 3355 3356DEFHEADING() 3357 3358DEFHEADING(Debug/Expert options:) 3359 3360DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg, 3361 "-fw_cfg [name=]<name>,file=<file>\n" 3362 " add named fw_cfg entry with contents from file\n" 3363 "-fw_cfg [name=]<name>,string=<str>\n" 3364 " add named fw_cfg entry with contents from string\n", 3365 QEMU_ARCH_ALL) 3366SRST 3367``-fw_cfg [name=]name,file=file`` 3368 Add named fw\_cfg entry with contents from file file. 3369 3370``-fw_cfg [name=]name,string=str`` 3371 Add named fw\_cfg entry with contents from string str. 3372 3373 The terminating NUL character of the contents of str will not be 3374 included as part of the fw\_cfg item data. To insert contents with 3375 embedded NUL characters, you have to use the file parameter. 3376 3377 The fw\_cfg entries are passed by QEMU through to the guest. 3378 3379 Example: 3380 3381 :: 3382 3383 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin 3384 3385 creates an fw\_cfg entry named opt/com.mycompany/blob with contents 3386 from ./my\_blob.bin. 3387ERST 3388 3389DEF("serial", HAS_ARG, QEMU_OPTION_serial, \ 3390 "-serial dev redirect the serial port to char device 'dev'\n", 3391 QEMU_ARCH_ALL) 3392SRST 3393``-serial dev`` 3394 Redirect the virtual serial port to host character device dev. The 3395 default device is ``vc`` in graphical mode and ``stdio`` in non 3396 graphical mode. 3397 3398 This option can be used several times to simulate up to 4 serial 3399 ports. 3400 3401 Use ``-serial none`` to disable all serial ports. 3402 3403 Available character devices are: 3404 3405 ``vc[:WxH]`` 3406 Virtual console. Optionally, a width and height can be given in 3407 pixel with 3408 3409 :: 3410 3411 vc:800x600 3412 3413 It is also possible to specify width or height in characters: 3414 3415 :: 3416 3417 vc:80Cx24C 3418 3419 ``pty`` 3420 [Linux only] Pseudo TTY (a new PTY is automatically allocated) 3421 3422 ``none`` 3423 No device is allocated. 3424 3425 ``null`` 3426 void device 3427 3428 ``chardev:id`` 3429 Use a named character device defined with the ``-chardev`` 3430 option. 3431 3432 ``/dev/XXX`` 3433 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial 3434 port parameters are set according to the emulated ones. 3435 3436 ``/dev/parportN`` 3437 [Linux only, parallel port only] Use host parallel port N. 3438 Currently SPP and EPP parallel port features can be used. 3439 3440 ``file:filename`` 3441 Write output to filename. No character can be read. 3442 3443 ``stdio`` 3444 [Unix only] standard input/output 3445 3446 ``pipe:filename`` 3447 name pipe filename 3448 3449 ``COMn`` 3450 [Windows only] Use host serial port n 3451 3452 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]`` 3453 This implements UDP Net Console. When remote\_host or src\_ip 3454 are not specified they default to ``0.0.0.0``. When not using a 3455 specified src\_port a random port is automatically chosen. 3456 3457 If you just want a simple readonly console you can use 3458 ``netcat`` or ``nc``, by starting QEMU with: 3459 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time 3460 QEMU writes something to that port it will appear in the 3461 netconsole session. 3462 3463 If you plan to send characters back via netconsole or you want 3464 to stop and start QEMU a lot of times, you should have QEMU use 3465 the same source port each time by using something like ``-serial 3466 udp::4555@:4556`` to QEMU. Another approach is to use a patched 3467 version of netcat which can listen to a TCP port and send and 3468 receive characters via udp. If you have a patched version of 3469 netcat which activates telnet remote echo and single char 3470 transfer, then you can use the following options to set up a 3471 netcat redirector to allow telnet on port 5555 to access the 3472 QEMU port. 3473 3474 ``QEMU Options:`` 3475 -serial udp::4555@:4556 3476 3477 ``netcat options:`` 3478 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T 3479 3480 ``telnet options:`` 3481 localhost 5555 3482 3483 ``tcp:[host]:port[,server][,nowait][,nodelay][,reconnect=seconds]`` 3484 The TCP Net Console has two modes of operation. It can send the 3485 serial I/O to a location or wait for a connection from a 3486 location. By default the TCP Net Console is sent to host at the 3487 port. If you use the server option QEMU will wait for a client 3488 socket application to connect to the port before continuing, 3489 unless the ``nowait`` option was specified. The ``nodelay`` 3490 option disables the Nagle buffering algorithm. The ``reconnect`` 3491 option only applies if noserver is set, if the connection goes 3492 down it will attempt to reconnect at the given interval. If host 3493 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a 3494 time is accepted. You can use ``telnet`` to connect to the 3495 corresponding character device. 3496 3497 ``Example to send tcp console to 192.168.0.2 port 4444`` 3498 -serial tcp:192.168.0.2:4444 3499 3500 ``Example to listen and wait on port 4444 for connection`` 3501 -serial tcp::4444,server 3502 3503 ``Example to not wait and listen on ip 192.168.0.100 port 4444`` 3504 -serial tcp:192.168.0.100:4444,server,nowait 3505 3506 ``telnet:host:port[,server][,nowait][,nodelay]`` 3507 The telnet protocol is used instead of raw tcp sockets. The 3508 options work the same as if you had specified ``-serial tcp``. 3509 The difference is that the port acts like a telnet server or 3510 client using telnet option negotiation. This will also allow you 3511 to send the MAGIC\_SYSRQ sequence if you use a telnet that 3512 supports sending the break sequence. Typically in unix telnet 3513 you do it with Control-] and then type "send break" followed by 3514 pressing the enter key. 3515 3516 ``websocket:host:port,server[,nowait][,nodelay]`` 3517 The WebSocket protocol is used instead of raw tcp socket. The 3518 port acts as a WebSocket server. Client mode is not supported. 3519 3520 ``unix:path[,server][,nowait][,reconnect=seconds]`` 3521 A unix domain socket is used instead of a tcp socket. The option 3522 works the same as if you had specified ``-serial tcp`` except 3523 the unix domain socket path is used for connections. 3524 3525 ``mon:dev_string`` 3526 This is a special option to allow the monitor to be multiplexed 3527 onto another serial port. The monitor is accessed with key 3528 sequence of Control-a and then pressing c. dev\_string should be 3529 any one of the serial devices specified above. An example to 3530 multiplex the monitor onto a telnet server listening on port 3531 4444 would be: 3532 3533 ``-serial mon:telnet::4444,server,nowait`` 3534 3535 When the monitor is multiplexed to stdio in this way, Ctrl+C 3536 will not terminate QEMU any more but will be passed to the guest 3537 instead. 3538 3539 ``braille`` 3540 Braille device. This will use BrlAPI to display the braille 3541 output on a real or fake device. 3542 3543 ``msmouse`` 3544 Three button serial mouse. Configure the guest to use Microsoft 3545 protocol. 3546ERST 3547 3548DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \ 3549 "-parallel dev redirect the parallel port to char device 'dev'\n", 3550 QEMU_ARCH_ALL) 3551SRST 3552``-parallel dev`` 3553 Redirect the virtual parallel port to host device dev (same devices 3554 as the serial port). On Linux hosts, ``/dev/parportN`` can be used 3555 to use hardware devices connected on the corresponding host parallel 3556 port. 3557 3558 This option can be used several times to simulate up to 3 parallel 3559 ports. 3560 3561 Use ``-parallel none`` to disable all parallel ports. 3562ERST 3563 3564DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \ 3565 "-monitor dev redirect the monitor to char device 'dev'\n", 3566 QEMU_ARCH_ALL) 3567SRST 3568``-monitor dev`` 3569 Redirect the monitor to host device dev (same devices as the serial 3570 port). The default device is ``vc`` in graphical mode and ``stdio`` 3571 in non graphical mode. Use ``-monitor none`` to disable the default 3572 monitor. 3573ERST 3574DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \ 3575 "-qmp dev like -monitor but opens in 'control' mode\n", 3576 QEMU_ARCH_ALL) 3577SRST 3578``-qmp dev`` 3579 Like -monitor but opens in 'control' mode. 3580ERST 3581DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \ 3582 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n", 3583 QEMU_ARCH_ALL) 3584SRST 3585``-qmp-pretty dev`` 3586 Like -qmp but uses pretty JSON formatting. 3587ERST 3588 3589DEF("mon", HAS_ARG, QEMU_OPTION_mon, \ 3590 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL) 3591SRST 3592``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]`` 3593 Setup monitor on chardev name. ``pretty`` turns on JSON pretty 3594 printing easing human reading and debugging. 3595ERST 3596 3597DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \ 3598 "-debugcon dev redirect the debug console to char device 'dev'\n", 3599 QEMU_ARCH_ALL) 3600SRST 3601``-debugcon dev`` 3602 Redirect the debug console to host device dev (same devices as the 3603 serial port). The debug console is an I/O port which is typically 3604 port 0xe9; writing to that I/O port sends output to this device. The 3605 default device is ``vc`` in graphical mode and ``stdio`` in non 3606 graphical mode. 3607ERST 3608 3609DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \ 3610 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL) 3611SRST 3612``-pidfile file`` 3613 Store the QEMU process PID in file. It is useful if you launch QEMU 3614 from a script. 3615ERST 3616 3617DEF("singlestep", 0, QEMU_OPTION_singlestep, \ 3618 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL) 3619SRST 3620``-singlestep`` 3621 Run the emulation in single step mode. 3622ERST 3623 3624DEF("preconfig", 0, QEMU_OPTION_preconfig, \ 3625 "--preconfig pause QEMU before machine is initialized (experimental)\n", 3626 QEMU_ARCH_ALL) 3627SRST 3628``--preconfig`` 3629 Pause QEMU for interactive configuration before the machine is 3630 created, which allows querying and configuring properties that will 3631 affect machine initialization. Use QMP command 'x-exit-preconfig' to 3632 exit the preconfig state and move to the next state (i.e. run guest 3633 if -S isn't used or pause the second time if -S is used). This 3634 option is experimental. 3635ERST 3636 3637DEF("S", 0, QEMU_OPTION_S, \ 3638 "-S freeze CPU at startup (use 'c' to start execution)\n", 3639 QEMU_ARCH_ALL) 3640SRST 3641``-S`` 3642 Do not start CPU at startup (you must type 'c' in the monitor). 3643ERST 3644 3645DEF("realtime", HAS_ARG, QEMU_OPTION_realtime, 3646 "-realtime [mlock=on|off]\n" 3647 " run qemu with realtime features\n" 3648 " mlock=on|off controls mlock support (default: on)\n", 3649 QEMU_ARCH_ALL) 3650SRST 3651``-realtime mlock=on|off`` 3652 Run qemu with realtime features. mlocking qemu and guest memory can 3653 be enabled via ``mlock=on`` (enabled by default). 3654ERST 3655 3656DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit, 3657 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n" 3658 " run qemu with overcommit hints\n" 3659 " mem-lock=on|off controls memory lock support (default: off)\n" 3660 " cpu-pm=on|off controls cpu power management (default: off)\n", 3661 QEMU_ARCH_ALL) 3662SRST 3663``-overcommit mem-lock=on|off`` 3664 \ 3665``-overcommit cpu-pm=on|off`` 3666 Run qemu with hints about host resource overcommit. The default is 3667 to assume that host overcommits all resources. 3668 3669 Locking qemu and guest memory can be enabled via ``mem-lock=on`` 3670 (disabled by default). This works when host memory is not 3671 overcommitted and reduces the worst-case latency for guest. This is 3672 equivalent to ``realtime``. 3673 3674 Guest ability to manage power state of host cpus (increasing latency 3675 for other processes on the same host cpu, but decreasing latency for 3676 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This 3677 works best when host CPU is not overcommitted. When used, host 3678 estimates of CPU cycle and power utilization will be incorrect, not 3679 taking into account guest idle time. 3680ERST 3681 3682DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \ 3683 "-gdb dev wait for gdb connection on 'dev'\n", QEMU_ARCH_ALL) 3684SRST 3685``-gdb dev`` 3686 Wait for gdb connection on device dev (see 3687 :ref:`gdb_005fusage`). Typical connections will likely be 3688 TCP-based, but also UDP, pseudo TTY, or even stdio are reasonable 3689 use case. The latter is allowing to start QEMU from within gdb and 3690 establish the connection via a pipe: 3691 3692 .. parsed-literal:: 3693 3694 (gdb) target remote | exec |qemu_system| -gdb stdio ... 3695ERST 3696 3697DEF("s", 0, QEMU_OPTION_s, \ 3698 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n", 3699 QEMU_ARCH_ALL) 3700SRST 3701``-s`` 3702 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234 3703 (see :ref:`gdb_005fusage`). 3704ERST 3705 3706DEF("d", HAS_ARG, QEMU_OPTION_d, \ 3707 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n", 3708 QEMU_ARCH_ALL) 3709SRST 3710``-d item1[,...]`` 3711 Enable logging of specified items. Use '-d help' for a list of log 3712 items. 3713ERST 3714 3715DEF("D", HAS_ARG, QEMU_OPTION_D, \ 3716 "-D logfile output log to logfile (default stderr)\n", 3717 QEMU_ARCH_ALL) 3718SRST 3719``-D logfile`` 3720 Output log in logfile instead of to stderr 3721ERST 3722 3723DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \ 3724 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n", 3725 QEMU_ARCH_ALL) 3726SRST 3727``-dfilter range1[,...]`` 3728 Filter debug output to that relevant to a range of target addresses. 3729 The filter spec can be either start+size, start-size or start..end 3730 where start end and size are the addresses and sizes required. For 3731 example: 3732 3733 :: 3734 3735 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000 3736 3737 Will dump output for any code in the 0x1000 sized block starting at 3738 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and 3739 another 0x1000 sized block starting at 0xffffffc00005f000. 3740ERST 3741 3742DEF("seed", HAS_ARG, QEMU_OPTION_seed, \ 3743 "-seed number seed the pseudo-random number generator\n", 3744 QEMU_ARCH_ALL) 3745SRST 3746``-seed number`` 3747 Force the guest to use a deterministic pseudo-random number 3748 generator, seeded with number. This does not affect crypto routines 3749 within the host. 3750ERST 3751 3752DEF("L", HAS_ARG, QEMU_OPTION_L, \ 3753 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n", 3754 QEMU_ARCH_ALL) 3755SRST 3756``-L path`` 3757 Set the directory for the BIOS, VGA BIOS and keymaps. 3758 3759 To list all the data directories, use ``-L help``. 3760ERST 3761 3762DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ 3763 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) 3764SRST 3765``-bios file`` 3766 Set the filename for the BIOS. 3767ERST 3768 3769DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ 3770 "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ALL) 3771SRST 3772``-enable-kvm`` 3773 Enable KVM full virtualization support. This option is only 3774 available if KVM support is enabled when compiling. 3775ERST 3776 3777DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid, 3778 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL) 3779DEF("xen-attach", 0, QEMU_OPTION_xen_attach, 3780 "-xen-attach attach to existing xen domain\n" 3781 " libxl will use this when starting QEMU\n", 3782 QEMU_ARCH_ALL) 3783DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict, 3784 "-xen-domid-restrict restrict set of available xen operations\n" 3785 " to specified domain id. (Does not affect\n" 3786 " xenpv machine type).\n", 3787 QEMU_ARCH_ALL) 3788SRST 3789``-xen-domid id`` 3790 Specify xen guest domain id (XEN only). 3791 3792``-xen-attach`` 3793 Attach to existing xen domain. libxl will use this when starting 3794 QEMU (XEN only). Restrict set of available xen operations to 3795 specified domain id (XEN only). 3796ERST 3797 3798DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \ 3799 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL) 3800SRST 3801``-no-reboot`` 3802 Exit instead of rebooting. 3803ERST 3804 3805DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \ 3806 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL) 3807SRST 3808``-no-shutdown`` 3809 Don't exit QEMU on guest shutdown, but instead only stop the 3810 emulation. This allows for instance switching to monitor to commit 3811 changes to the disk image. 3812ERST 3813 3814DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \ 3815 "-loadvm [tag|id]\n" \ 3816 " start right away with a saved state (loadvm in monitor)\n", 3817 QEMU_ARCH_ALL) 3818SRST 3819``-loadvm file`` 3820 Start right away with a saved state (``loadvm`` in monitor) 3821ERST 3822 3823#ifndef _WIN32 3824DEF("daemonize", 0, QEMU_OPTION_daemonize, \ 3825 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL) 3826#endif 3827SRST 3828``-daemonize`` 3829 Daemonize the QEMU process after initialization. QEMU will not 3830 detach from standard IO until it is ready to receive connections on 3831 any of its devices. This option is a useful way for external 3832 programs to launch QEMU without having to cope with initialization 3833 race conditions. 3834ERST 3835 3836DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \ 3837 "-option-rom rom load a file, rom, into the option ROM space\n", 3838 QEMU_ARCH_ALL) 3839SRST 3840``-option-rom file`` 3841 Load the contents of file as an option ROM. This option is useful to 3842 load things like EtherBoot. 3843ERST 3844 3845DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \ 3846 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \ 3847 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n", 3848 QEMU_ARCH_ALL) 3849 3850SRST 3851``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]`` 3852 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at 3853 the current UTC or local time, respectively. ``localtime`` is 3854 required for correct date in MS-DOS or Windows. To start at a 3855 specific point in time, provide datetime in the format 3856 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC. 3857 3858 By default the RTC is driven by the host system time. This allows 3859 using of the RTC as accurate reference clock inside the guest, 3860 specifically if the host time is smoothly following an accurate 3861 external reference clock, e.g. via NTP. If you want to isolate the 3862 guest time from the host, you can set ``clock`` to ``rt`` instead, 3863 which provides a host monotonic clock if host support it. To even 3864 prevent the RTC from progressing during suspension, you can set 3865 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is 3866 recommended especially in icount mode in order to preserve 3867 determinism; however, note that in icount mode the speed of the 3868 virtual clock is variable and can in general differ from the host 3869 clock. 3870 3871 Enable ``driftfix`` (i386 targets only) if you experience time drift 3872 problems, specifically with Windows' ACPI HAL. This option will try 3873 to figure out how many timer interrupts were not processed by the 3874 Windows guest and will re-inject them. 3875ERST 3876 3877DEF("icount", HAS_ARG, QEMU_OPTION_icount, \ 3878 "-icount [shift=N|auto][,align=on|off][,sleep=on|off,rr=record|replay,rrfile=<filename>,rrsnapshot=<snapshot>]\n" \ 3879 " enable virtual instruction counter with 2^N clock ticks per\n" \ 3880 " instruction, enable aligning the host and virtual clocks\n" \ 3881 " or disable real time cpu sleeping\n", QEMU_ARCH_ALL) 3882SRST 3883``-icount [shift=N|auto][,rr=record|replay,rrfile=filename,rrsnapshot=snapshot]`` 3884 Enable virtual instruction counter. The virtual cpu will execute one 3885 instruction every 2^N ns of virtual time. If ``auto`` is specified 3886 then the virtual cpu speed will be automatically adjusted to keep 3887 virtual time within a few seconds of real time. 3888 3889 When the virtual cpu is sleeping, the virtual time will advance at 3890 default speed unless ``sleep=on|off`` is specified. With 3891 ``sleep=on|off``, the virtual time will jump to the next timer 3892 deadline instantly whenever the virtual cpu goes to sleep mode and 3893 will not advance if no timer is enabled. This behavior give 3894 deterministic execution times from the guest point of view. 3895 3896 Note that while this option can give deterministic behavior, it does 3897 not provide cycle accurate emulation. Modern CPUs contain 3898 superscalar out of order cores with complex cache hierarchies. The 3899 number of instructions executed often has little or no correlation 3900 with actual performance. 3901 3902 ``align=on`` will activate the delay algorithm which will try to 3903 synchronise the host clock and the virtual clock. The goal is to 3904 have a guest running at the real frequency imposed by the shift 3905 option. Whenever the guest clock is behind the host clock and if 3906 ``align=on`` is specified then we print a message to the user to 3907 inform about the delay. Currently this option does not work when 3908 ``shift`` is ``auto``. Note: The sync algorithm will work for those 3909 shift values for which the guest clock runs ahead of the host clock. 3910 Typically this happens when the shift value is high (how high 3911 depends on the host machine). 3912 3913 When ``rr`` option is specified deterministic record/replay is 3914 enabled. Replay log is written into filename file in record mode and 3915 read from this file in replay mode. 3916 3917 Option rrsnapshot is used to create new vm snapshot named snapshot 3918 at the start of execution recording. In replay mode this option is 3919 used to load the initial VM state. 3920ERST 3921 3922DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \ 3923 "-watchdog model\n" \ 3924 " enable virtual hardware watchdog [default=none]\n", 3925 QEMU_ARCH_ALL) 3926SRST 3927``-watchdog model`` 3928 Create a virtual hardware watchdog device. Once enabled (by a guest 3929 action), the watchdog must be periodically polled by an agent inside 3930 the guest or else the guest will be restarted. Choose a model for 3931 which your guest has drivers. 3932 3933 The model is the model of hardware watchdog to emulate. Use 3934 ``-watchdog help`` to list available hardware models. Only one 3935 watchdog can be enabled for a guest. 3936 3937 The following models may be available: 3938 3939 ``ib700`` 3940 iBASE 700 is a very simple ISA watchdog with a single timer. 3941 3942 ``i6300esb`` 3943 Intel 6300ESB I/O controller hub is a much more featureful 3944 PCI-based dual-timer watchdog. 3945 3946 ``diag288`` 3947 A virtual watchdog for s390x backed by the diagnose 288 3948 hypercall (currently KVM only). 3949ERST 3950 3951DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \ 3952 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \ 3953 " action when watchdog fires [default=reset]\n", 3954 QEMU_ARCH_ALL) 3955SRST 3956``-watchdog-action action`` 3957 The action controls what QEMU will do when the watchdog timer 3958 expires. The default is ``reset`` (forcefully reset the guest). 3959 Other possible actions are: ``shutdown`` (attempt to gracefully 3960 shutdown the guest), ``poweroff`` (forcefully poweroff the guest), 3961 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the 3962 guest), ``debug`` (print a debug message and continue), or ``none`` 3963 (do nothing). 3964 3965 Note that the ``shutdown`` action requires that the guest responds 3966 to ACPI signals, which it may not be able to do in the sort of 3967 situations where the watchdog would have expired, and thus 3968 ``-watchdog-action shutdown`` is not recommended for production use. 3969 3970 Examples: 3971 3972 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700`` 3973 3974ERST 3975 3976DEF("echr", HAS_ARG, QEMU_OPTION_echr, \ 3977 "-echr chr set terminal escape character instead of ctrl-a\n", 3978 QEMU_ARCH_ALL) 3979SRST 3980``-echr numeric_ascii_value`` 3981 Change the escape character used for switching to the monitor when 3982 using monitor and serial sharing. The default is ``0x01`` when using 3983 the ``-nographic`` option. ``0x01`` is equal to pressing 3984 ``Control-a``. You can select a different character from the ascii 3985 control keys where 1 through 26 map to Control-a through Control-z. 3986 For instance you could use the either of the following to change the 3987 escape character to Control-t. 3988 3989 ``-echr 0x14``; \ ``-echr 20`` 3990 3991ERST 3992 3993DEF("show-cursor", 0, QEMU_OPTION_show_cursor, \ 3994 "-show-cursor show cursor\n", QEMU_ARCH_ALL) 3995SRST 3996``-show-cursor`` 3997 Show cursor. 3998ERST 3999 4000DEF("tb-size", HAS_ARG, QEMU_OPTION_tb_size, \ 4001 "-tb-size n set TB size\n", QEMU_ARCH_ALL) 4002SRST 4003``-tb-size n`` 4004 Set TCG translation block cache size. Deprecated, use 4005 '\ ``-accel tcg,tb-size=n``\ ' instead. 4006ERST 4007 4008DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \ 4009 "-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]\n" \ 4010 "-incoming rdma:host:port[,ipv4][,ipv6]\n" \ 4011 "-incoming unix:socketpath\n" \ 4012 " prepare for incoming migration, listen on\n" \ 4013 " specified protocol and socket address\n" \ 4014 "-incoming fd:fd\n" \ 4015 "-incoming exec:cmdline\n" \ 4016 " accept incoming migration on given file descriptor\n" \ 4017 " or from given external command\n" \ 4018 "-incoming defer\n" \ 4019 " wait for the URI to be specified via migrate_incoming\n", 4020 QEMU_ARCH_ALL) 4021SRST 4022``-incoming tcp:[host]:port[,to=maxport][,ipv4][,ipv6]`` 4023 \ 4024``-incoming rdma:host:port[,ipv4][,ipv6]`` 4025 Prepare for incoming migration, listen on a given tcp port. 4026 4027``-incoming unix:socketpath`` 4028 Prepare for incoming migration, listen on a given unix socket. 4029 4030``-incoming fd:fd`` 4031 Accept incoming migration from a given filedescriptor. 4032 4033``-incoming exec:cmdline`` 4034 Accept incoming migration as an output from specified external 4035 command. 4036 4037``-incoming defer`` 4038 Wait for the URI to be specified via migrate\_incoming. The monitor 4039 can be used to change settings (such as migration parameters) prior 4040 to issuing the migrate\_incoming to allow the migration to begin. 4041ERST 4042 4043DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \ 4044 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL) 4045SRST 4046``-only-migratable`` 4047 Only allow migratable devices. Devices will not be allowed to enter 4048 an unmigratable state. 4049ERST 4050 4051DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \ 4052 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL) 4053SRST 4054``-nodefaults`` 4055 Don't create default devices. Normally, QEMU sets the default 4056 devices like serial port, parallel port, virtual console, monitor 4057 device, VGA adapter, floppy and CD-ROM drive and others. The 4058 ``-nodefaults`` option will disable all those default devices. 4059ERST 4060 4061#ifndef _WIN32 4062DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \ 4063 "-chroot dir chroot to dir just before starting the VM\n", 4064 QEMU_ARCH_ALL) 4065#endif 4066SRST 4067``-chroot dir`` 4068 Immediately before starting guest execution, chroot to the specified 4069 directory. Especially useful in combination with -runas. 4070ERST 4071 4072#ifndef _WIN32 4073DEF("runas", HAS_ARG, QEMU_OPTION_runas, \ 4074 "-runas user change to user id user just before starting the VM\n" \ 4075 " user can be numeric uid:gid instead\n", 4076 QEMU_ARCH_ALL) 4077#endif 4078SRST 4079``-runas user`` 4080 Immediately before starting guest execution, drop root privileges, 4081 switching to the specified user. 4082ERST 4083 4084DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env, 4085 "-prom-env variable=value\n" 4086 " set OpenBIOS nvram variables\n", 4087 QEMU_ARCH_PPC | QEMU_ARCH_SPARC) 4088SRST 4089``-prom-env variable=value`` 4090 Set OpenBIOS nvram variable to given value (PPC, SPARC only). 4091 4092 :: 4093 4094 qemu-system-sparc -prom-env 'auto-boot?=false' \ 4095 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single' 4096 4097 :: 4098 4099 qemu-system-ppc -prom-env 'auto-boot?=false' \ 4100 -prom-env 'boot-device=hd:2,\yaboot' \ 4101 -prom-env 'boot-args=conf=hd:2,\yaboot.conf' 4102ERST 4103DEF("semihosting", 0, QEMU_OPTION_semihosting, 4104 "-semihosting semihosting mode\n", 4105 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 | 4106 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2) 4107SRST 4108``-semihosting`` 4109 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II only). 4110 4111 Note that this allows guest direct access to the host filesystem, so 4112 should only be used with a trusted guest OS. 4113 4114 See the -semihosting-config option documentation for further 4115 information about the facilities this enables. 4116ERST 4117DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, 4118 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \ 4119 " semihosting configuration\n", 4120QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 | 4121QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2) 4122SRST 4123``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]`` 4124 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II 4125 only). 4126 4127 Note that this allows guest direct access to the host filesystem, so 4128 should only be used with a trusted guest OS. 4129 4130 On Arm this implements the standard semihosting API, version 2.0. 4131 4132 On M68K this implements the "ColdFire GDB" interface used by 4133 libgloss. 4134 4135 Xtensa semihosting provides basic file IO calls, such as 4136 open/read/write/seek/select. Tensilica baremetal libc for ISS and 4137 linux platform "sim" use this interface. 4138 4139 ``target=native|gdb|auto`` 4140 Defines where the semihosting calls will be addressed, to QEMU 4141 (``native``) or to GDB (``gdb``). The default is ``auto``, which 4142 means ``gdb`` during debug sessions and ``native`` otherwise. 4143 4144 ``chardev=str1`` 4145 Send the output to a chardev backend output for native or auto 4146 output when not in gdb 4147 4148 ``arg=str1,arg=str2,...`` 4149 Allows the user to pass input arguments, and can be used 4150 multiple times to build up a list. The old-style 4151 ``-kernel``/``-append`` method of passing a command line is 4152 still supported for backward compatibility. If both the 4153 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are 4154 specified, the former is passed to semihosting as it always 4155 takes precedence. 4156ERST 4157DEF("old-param", 0, QEMU_OPTION_old_param, 4158 "-old-param old param mode\n", QEMU_ARCH_ARM) 4159SRST 4160``-old-param`` 4161 Old param mode (ARM only). 4162ERST 4163 4164DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ 4165 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ 4166 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \ 4167 " Enable seccomp mode 2 system call filter (default 'off').\n" \ 4168 " use 'obsolete' to allow obsolete system calls that are provided\n" \ 4169 " by the kernel, but typically no longer used by modern\n" \ 4170 " C library implementations.\n" \ 4171 " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \ 4172 " its privileges by blacklisting all set*uid|gid system calls.\n" \ 4173 " The value 'children' will deny set*uid|gid system calls for\n" \ 4174 " main QEMU process but will allow forks and execves to run unprivileged\n" \ 4175 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \ 4176 " blacklisting *fork and execve\n" \ 4177 " use 'resourcecontrol' to disable process affinity and schedular priority\n", 4178 QEMU_ARCH_ALL) 4179SRST 4180``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]`` 4181 Enable Seccomp mode 2 system call filter. 'on' will enable syscall 4182 filtering and 'off' will disable it. The default is 'off'. 4183 4184 ``obsolete=string`` 4185 Enable Obsolete system calls 4186 4187 ``elevateprivileges=string`` 4188 Disable set\*uid\|gid system calls 4189 4190 ``spawn=string`` 4191 Disable \*fork and execve 4192 4193 ``resourcecontrol=string`` 4194 Disable process affinity and schedular priority 4195ERST 4196 4197DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig, 4198 "-readconfig <file>\n", QEMU_ARCH_ALL) 4199SRST 4200``-readconfig file`` 4201 Read device configuration from file. This approach is useful when 4202 you want to spawn QEMU process with many command line options but 4203 you don't want to exceed the command line character limit. 4204ERST 4205DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig, 4206 "-writeconfig <file>\n" 4207 " read/write config file\n", QEMU_ARCH_ALL) 4208SRST 4209``-writeconfig file`` 4210 Write device configuration to file. The file can be either filename 4211 to save command line and device configuration into file or dash 4212 ``-``) character to print the output to stdout. This can be later 4213 used as input file for ``-readconfig`` option. 4214ERST 4215 4216DEF("no-user-config", 0, QEMU_OPTION_nouserconfig, 4217 "-no-user-config\n" 4218 " do not load default user-provided config files at startup\n", 4219 QEMU_ARCH_ALL) 4220SRST 4221``-no-user-config`` 4222 The ``-no-user-config`` option makes QEMU not load any of the 4223 user-provided config files on sysconfdir. 4224ERST 4225 4226DEF("trace", HAS_ARG, QEMU_OPTION_trace, 4227 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n" 4228 " specify tracing options\n", 4229 QEMU_ARCH_ALL) 4230SRST 4231``-trace [[enable=]pattern][,events=file][,file=file]`` 4232 .. include:: ../qemu-option-trace.rst.inc 4233 4234ERST 4235DEF("plugin", HAS_ARG, QEMU_OPTION_plugin, 4236 "-plugin [file=]<file>[,arg=<string>]\n" 4237 " load a plugin\n", 4238 QEMU_ARCH_ALL) 4239SRST 4240``-plugin file=file[,arg=string]`` 4241 Load a plugin. 4242 4243 ``file=file`` 4244 Load the given plugin from a shared library file. 4245 4246 ``arg=string`` 4247 Argument string passed to the plugin. (Can be given multiple 4248 times.) 4249ERST 4250 4251HXCOMM Internal use 4252DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL) 4253DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL) 4254 4255#ifdef __linux__ 4256DEF("enable-fips", 0, QEMU_OPTION_enablefips, 4257 "-enable-fips enable FIPS 140-2 compliance\n", 4258 QEMU_ARCH_ALL) 4259#endif 4260SRST 4261``-enable-fips`` 4262 Enable FIPS 140-2 compliance mode. 4263ERST 4264 4265HXCOMM Deprecated by -accel tcg 4266DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386) 4267 4268DEF("msg", HAS_ARG, QEMU_OPTION_msg, 4269 "-msg timestamp[=on|off]\n" 4270 " control error message format\n" 4271 " timestamp=on enables timestamps (default: off)\n", 4272 QEMU_ARCH_ALL) 4273SRST 4274``-msg timestamp[=on|off]`` 4275 Control error message format. 4276 4277 ``timestamp=on|off`` 4278 Prefix messages with a timestamp. Default is off. 4279ERST 4280 4281DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate, 4282 "-dump-vmstate <file>\n" 4283 " Output vmstate information in JSON format to file.\n" 4284 " Use the scripts/vmstate-static-checker.py file to\n" 4285 " check for possible regressions in migration code\n" 4286 " by comparing two such vmstate dumps.\n", 4287 QEMU_ARCH_ALL) 4288SRST 4289``-dump-vmstate file`` 4290 Dump json-encoded vmstate information for current machine type to 4291 file in file 4292ERST 4293 4294DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile, 4295 "-enable-sync-profile\n" 4296 " enable synchronization profiling\n", 4297 QEMU_ARCH_ALL) 4298SRST 4299``-enable-sync-profile`` 4300 Enable synchronization profiling. 4301ERST 4302 4303DEFHEADING() 4304 4305DEFHEADING(Generic object creation:) 4306 4307DEF("object", HAS_ARG, QEMU_OPTION_object, 4308 "-object TYPENAME[,PROP1=VALUE1,...]\n" 4309 " create a new object of type TYPENAME setting properties\n" 4310 " in the order they are specified. Note that the 'id'\n" 4311 " property must be set. These objects are placed in the\n" 4312 " '/objects' path.\n", 4313 QEMU_ARCH_ALL) 4314SRST 4315``-object typename[,prop1=value1,...]`` 4316 Create a new object of type typename setting properties in the order 4317 they are specified. Note that the 'id' property must be set. These 4318 objects are placed in the '/objects' path. 4319 4320 ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align`` 4321 Creates a memory file backend object, which can be used to back 4322 the guest RAM with huge pages. 4323 4324 The ``id`` parameter is a unique ID that will be used to 4325 reference this memory region when configuring the ``-numa`` 4326 argument. 4327 4328 The ``size`` option provides the size of the memory region, and 4329 accepts common suffixes, eg ``500M``. 4330 4331 The ``mem-path`` provides the path to either a shared memory or 4332 huge page filesystem mount. 4333 4334 The ``share`` boolean option determines whether the memory 4335 region is marked as private to QEMU, or shared. The latter 4336 allows a co-operating external process to access the QEMU memory 4337 region. 4338 4339 The ``share`` is also required for pvrdma devices due to 4340 limitations in the RDMA API provided by Linux. 4341 4342 Setting share=on might affect the ability to configure NUMA 4343 bindings for the memory backend under some circumstances, see 4344 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel 4345 source tree for additional details. 4346 4347 Setting the ``discard-data`` boolean option to on indicates that 4348 file contents can be destroyed when QEMU exits, to avoid 4349 unnecessarily flushing data to the backing file. Note that 4350 ``discard-data`` is only an optimization, and QEMU might not 4351 discard file contents if it aborts unexpectedly or is terminated 4352 using SIGKILL. 4353 4354 The ``merge`` boolean option enables memory merge, also known as 4355 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider 4356 the pages for memory deduplication. 4357 4358 Setting the ``dump`` boolean option to off excludes the memory 4359 from core dumps. This feature is also known as MADV\_DONTDUMP. 4360 4361 The ``prealloc`` boolean option enables memory preallocation. 4362 4363 The ``host-nodes`` option binds the memory range to a list of 4364 NUMA host nodes. 4365 4366 The ``policy`` option sets the NUMA policy to one of the 4367 following values: 4368 4369 ``default`` 4370 default host policy 4371 4372 ``preferred`` 4373 prefer the given host node list for allocation 4374 4375 ``bind`` 4376 restrict memory allocation to the given host node list 4377 4378 ``interleave`` 4379 interleave memory allocations across the given host node 4380 list 4381 4382 The ``align`` option specifies the base address alignment when 4383 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg 4384 ``2M``. Some backend store specified by ``mem-path`` requires an 4385 alignment different than the default one used by QEMU, eg the 4386 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In 4387 such cases, users can specify the required alignment via this 4388 option. 4389 4390 The ``pmem`` option specifies whether the backing file specified 4391 by ``mem-path`` is in host persistent memory that can be 4392 accessed using the SNIA NVM programming model (e.g. Intel 4393 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary 4394 operations to guarantee the persistence of its own writes to 4395 ``mem-path`` (e.g. in vNVDIMM label emulation and live 4396 migration). Also, we will map the backend-file with MAP\_SYNC 4397 flag, which ensures the file metadata is in sync for 4398 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC 4399 requires support from both the host kernel (since Linux kernel 4400 4.15) and the filesystem of ``mem-path`` mounted with DAX 4401 option. 4402 4403 ``-object memory-backend-ram,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave`` 4404 Creates a memory backend object, which can be used to back the 4405 guest RAM. Memory backend objects offer more control than the 4406 ``-m`` option that is traditionally used to define guest RAM. 4407 Please refer to ``memory-backend-file`` for a description of the 4408 options. 4409 4410 ``-object memory-backend-memfd,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave,seal=on|off,hugetlb=on|off,hugetlbsize=size`` 4411 Creates an anonymous memory file backend object, which allows 4412 QEMU to share the memory with an external process (e.g. when 4413 using vhost-user). The memory is allocated with memfd and 4414 optional sealing. (Linux only) 4415 4416 The ``seal`` option creates a sealed-file, that will block 4417 further resizing the memory ('on' by default). 4418 4419 The ``hugetlb`` option specify the file to be created resides in 4420 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction 4421 with the ``hugetlb`` option, the ``hugetlbsize`` option specify 4422 the hugetlb page size on systems that support multiple hugetlb 4423 page sizes (it must be a power of 2 value supported by the 4424 system). 4425 4426 In some versions of Linux, the ``hugetlb`` option is 4427 incompatible with the ``seal`` option (requires at least Linux 4428 4.16). 4429 4430 Please refer to ``memory-backend-file`` for a description of the 4431 other options. 4432 4433 The ``share`` boolean option is on by default with memfd. 4434 4435 ``-object rng-builtin,id=id`` 4436 Creates a random number generator backend which obtains entropy 4437 from QEMU builtin functions. The ``id`` parameter is a unique ID 4438 that will be used to reference this entropy backend from the 4439 ``virtio-rng`` device. By default, the ``virtio-rng`` device 4440 uses this RNG backend. 4441 4442 ``-object rng-random,id=id,filename=/dev/random`` 4443 Creates a random number generator backend which obtains entropy 4444 from a device on the host. The ``id`` parameter is a unique ID 4445 that will be used to reference this entropy backend from the 4446 ``virtio-rng`` device. The ``filename`` parameter specifies 4447 which file to obtain entropy from and if omitted defaults to 4448 ``/dev/urandom``. 4449 4450 ``-object rng-egd,id=id,chardev=chardevid`` 4451 Creates a random number generator backend which obtains entropy 4452 from an external daemon running on the host. The ``id`` 4453 parameter is a unique ID that will be used to reference this 4454 entropy backend from the ``virtio-rng`` device. The ``chardev`` 4455 parameter is the unique ID of a character device backend that 4456 provides the connection to the RNG daemon. 4457 4458 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off`` 4459 Creates a TLS anonymous credentials object, which can be used to 4460 provide TLS support on network backends. The ``id`` parameter is 4461 a unique ID which network backends will use to access the 4462 credentials. The ``endpoint`` is either ``server`` or ``client`` 4463 depending on whether the QEMU network backend that uses the 4464 credentials will be acting as a client or as a server. If 4465 ``verify-peer`` is enabled (the default) then once the handshake 4466 is completed, the peer credentials will be verified, though this 4467 is a no-op for anonymous credentials. 4468 4469 The dir parameter tells QEMU where to find the credential files. 4470 For server endpoints, this directory may contain a file 4471 dh-params.pem providing diffie-hellman parameters to use for the 4472 TLS server. If the file is missing, QEMU will generate a set of 4473 DH parameters at startup. This is a computationally expensive 4474 operation that consumes random pool entropy, so it is 4475 recommended that a persistent set of parameters be generated 4476 upfront and saved. 4477 4478 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]`` 4479 Creates a TLS Pre-Shared Keys (PSK) credentials object, which 4480 can be used to provide TLS support on network backends. The 4481 ``id`` parameter is a unique ID which network backends will use 4482 to access the credentials. The ``endpoint`` is either ``server`` 4483 or ``client`` depending on whether the QEMU network backend that 4484 uses the credentials will be acting as a client or as a server. 4485 For clients only, ``username`` is the username which will be 4486 sent to the server. If omitted it defaults to "qemu". 4487 4488 The dir parameter tells QEMU where to find the keys file. It is 4489 called "dir/keys.psk" and contains "username:key" pairs. This 4490 file can most easily be created using the GnuTLS ``psktool`` 4491 program. 4492 4493 For server endpoints, dir may also contain a file dh-params.pem 4494 providing diffie-hellman parameters to use for the TLS server. 4495 If the file is missing, QEMU will generate a set of DH 4496 parameters at startup. This is a computationally expensive 4497 operation that consumes random pool entropy, so it is 4498 recommended that a persistent set of parameters be generated up 4499 front and saved. 4500 4501 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id`` 4502 Creates a TLS anonymous credentials object, which can be used to 4503 provide TLS support on network backends. The ``id`` parameter is 4504 a unique ID which network backends will use to access the 4505 credentials. The ``endpoint`` is either ``server`` or ``client`` 4506 depending on whether the QEMU network backend that uses the 4507 credentials will be acting as a client or as a server. If 4508 ``verify-peer`` is enabled (the default) then once the handshake 4509 is completed, the peer credentials will be verified. With x509 4510 certificates, this implies that the clients must be provided 4511 with valid client certificates too. 4512 4513 The dir parameter tells QEMU where to find the credential files. 4514 For server endpoints, this directory may contain a file 4515 dh-params.pem providing diffie-hellman parameters to use for the 4516 TLS server. If the file is missing, QEMU will generate a set of 4517 DH parameters at startup. This is a computationally expensive 4518 operation that consumes random pool entropy, so it is 4519 recommended that a persistent set of parameters be generated 4520 upfront and saved. 4521 4522 For x509 certificate credentials the directory will contain 4523 further files providing the x509 certificates. The certificates 4524 must be stored in PEM format, in filenames ca-cert.pem, 4525 ca-crl.pem (optional), server-cert.pem (only servers), 4526 server-key.pem (only servers), client-cert.pem (only clients), 4527 and client-key.pem (only clients). 4528 4529 For the server-key.pem and client-key.pem files which contain 4530 sensitive private keys, it is possible to use an encrypted 4531 version by providing the passwordid parameter. This provides the 4532 ID of a previously created ``secret`` object containing the 4533 password for decryption. 4534 4535 The priority parameter allows to override the global default 4536 priority used by gnutls. This can be useful if the system 4537 administrator needs to use a weaker set of crypto priorities for 4538 QEMU without potentially forcing the weakness onto all 4539 applications. Or conversely if one wants wants a stronger 4540 default for QEMU than for all other applications, they can do 4541 this through this parameter. Its format is a gnutls priority 4542 string as described at 4543 https://gnutls.org/manual/html_node/Priority-Strings.html. 4544 4545 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]`` 4546 Interval t can't be 0, this filter batches the packet delivery: 4547 all packets arriving in a given interval on netdev netdevid are 4548 delayed until the end of the interval. Interval is in 4549 microseconds. ``status`` is optional that indicate whether the 4550 netfilter is on (enabled) or off (disabled), the default status 4551 for netfilter will be 'on'. 4552 4553 queue all\|rx\|tx is an option that can be applied to any 4554 netfilter. 4555 4556 ``all``: the filter is attached both to the receive and the 4557 transmit queue of the netdev (default). 4558 4559 ``rx``: the filter is attached to the receive queue of the 4560 netdev, where it will receive packets sent to the netdev. 4561 4562 ``tx``: the filter is attached to the transmit queue of the 4563 netdev, where it will receive packets sent by the netdev. 4564 4565 position head\|tail\|id=<id> is an option to specify where the 4566 filter should be inserted in the filter list. It can be applied 4567 to any netfilter. 4568 4569 ``head``: the filter is inserted at the head of the filter list, 4570 before any existing filters. 4571 4572 ``tail``: the filter is inserted at the tail of the filter list, 4573 behind any existing filters (default). 4574 4575 ``id=<id>``: the filter is inserted before or behind the filter 4576 specified by <id>, see the insert option below. 4577 4578 insert behind\|before is an option to specify where to insert 4579 the new filter relative to the one specified with 4580 position=id=<id>. It can be applied to any netfilter. 4581 4582 ``before``: insert before the specified filter. 4583 4584 ``behind``: insert behind the specified filter (default). 4585 4586 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 4587 filter-mirror on netdev netdevid,mirror net packet to 4588 chardevchardevid, if it has the vnet\_hdr\_support flag, 4589 filter-mirror will mirror packet with vnet\_hdr\_len. 4590 4591 ``-object filter-redirector,id=id,netdev=netdevid,indev=chardevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 4592 filter-redirector on netdev netdevid,redirect filter's net 4593 packet to chardev chardevid,and redirect indev's packet to 4594 filter.if it has the vnet\_hdr\_support flag, filter-redirector 4595 will redirect packet with vnet\_hdr\_len. Create a 4596 filter-redirector we need to differ outdev id from indev id, id 4597 can not be the same. we can just use indev or outdev, but at 4598 least one of indev or outdev need to be specified. 4599 4600 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 4601 Filter-rewriter is a part of COLO project.It will rewrite tcp 4602 packet to secondary from primary to keep secondary tcp 4603 connection,and rewrite tcp packet to primary from secondary make 4604 tcp packet can be handled by client.if it has the 4605 vnet\_hdr\_support flag, we can parse packet with vnet header. 4606 4607 usage: colo secondary: -object 4608 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object 4609 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object 4610 filter-rewriter,id=rew0,netdev=hn0,queue=all 4611 4612 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]`` 4613 Dump the network traffic on netdev dev to the file specified by 4614 filename. At most len bytes (64k by default) per packet are 4615 stored. The file format is libpcap, so it can be analyzed with 4616 tools such as tcpdump or Wireshark. 4617 4618 ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id]`` 4619 Colo-compare gets packet from primary\_inchardevid and 4620 secondary\_inchardevid, than compare primary packet with 4621 secondary packet. If the packets are same, we will output 4622 primary packet to outdevchardevid, else we will notify 4623 colo-frame do checkpoint and send primary packet to 4624 outdevchardevid. In order to improve efficiency, we need to put 4625 the task of comparison in another thread. If it has the 4626 vnet\_hdr\_support flag, colo compare will send/recv packet with 4627 vnet\_hdr\_len. If you want to use Xen COLO, will need the 4628 notify\_dev to notify Xen colo-frame to do checkpoint. 4629 4630 we must use it with the help of filter-mirror and 4631 filter-redirector. 4632 4633 :: 4634 4635 KVM COLO 4636 4637 primary: 4638 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 4639 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 4640 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait 4641 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait 4642 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait 4643 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 4644 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait 4645 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 4646 -object iothread,id=iothread1 4647 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 4648 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 4649 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 4650 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1 4651 4652 secondary: 4653 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 4654 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 4655 -chardev socket,id=red0,host=3.3.3.3,port=9003 4656 -chardev socket,id=red1,host=3.3.3.3,port=9004 4657 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 4658 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 4659 4660 4661 Xen COLO 4662 4663 primary: 4664 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 4665 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 4666 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server,nowait 4667 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server,nowait 4668 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server,nowait 4669 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 4670 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server,nowait 4671 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 4672 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server,nowait 4673 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 4674 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 4675 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 4676 -object iothread,id=iothread1 4677 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1 4678 4679 secondary: 4680 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 4681 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 4682 -chardev socket,id=red0,host=3.3.3.3,port=9003 4683 -chardev socket,id=red1,host=3.3.3.3,port=9004 4684 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 4685 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 4686 4687 If you want to know the detail of above command line, you can 4688 read the colo-compare git log. 4689 4690 ``-object cryptodev-backend-builtin,id=id[,queues=queues]`` 4691 Creates a cryptodev backend which executes crypto opreation from 4692 the QEMU cipher APIS. The id parameter is a unique ID that will 4693 be used to reference this cryptodev backend from the 4694 ``virtio-crypto`` device. The queues parameter is optional, 4695 which specify the queue number of cryptodev backend, the default 4696 of queues is 1. 4697 4698 .. parsed-literal:: 4699 4700 # |qemu_system| \ 4701 [...] \ 4702 -object cryptodev-backend-builtin,id=cryptodev0 \ 4703 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \ 4704 [...] 4705 4706 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]`` 4707 Creates a vhost-user cryptodev backend, backed by a chardev 4708 chardevid. The id parameter is a unique ID that will be used to 4709 reference this cryptodev backend from the ``virtio-crypto`` 4710 device. The chardev should be a unix domain socket backed one. 4711 The vhost-user uses a specifically defined protocol to pass 4712 vhost ioctl replacement messages to an application on the other 4713 end of the socket. The queues parameter is optional, which 4714 specify the queue number of cryptodev backend for multiqueue 4715 vhost-user, the default of queues is 1. 4716 4717 .. parsed-literal:: 4718 4719 # |qemu_system| \ 4720 [...] \ 4721 -chardev socket,id=chardev0,path=/path/to/socket \ 4722 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \ 4723 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \ 4724 [...] 4725 4726 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]`` 4727 \ 4728 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]`` 4729 Defines a secret to store a password, encryption key, or some 4730 other sensitive data. The sensitive data can either be passed 4731 directly via the data parameter, or indirectly via the file 4732 parameter. Using the data parameter is insecure unless the 4733 sensitive data is encrypted. 4734 4735 The sensitive data can be provided in raw format (the default), 4736 or base64. When encoded as JSON, the raw format only supports 4737 valid UTF-8 characters, so base64 is recommended for sending 4738 binary data. QEMU will convert from which ever format is 4739 provided to the format it needs internally. eg, an RBD password 4740 can be provided in raw format, even though it will be base64 4741 encoded when passed onto the RBD sever. 4742 4743 For added protection, it is possible to encrypt the data 4744 associated with a secret using the AES-256-CBC cipher. Use of 4745 encryption is indicated by providing the keyid and iv 4746 parameters. The keyid parameter provides the ID of a previously 4747 defined secret that contains the AES-256 decryption key. This 4748 key should be 32-bytes long and be base64 encoded. The iv 4749 parameter provides the random initialization vector used for 4750 encryption of this particular secret and should be a base64 4751 encrypted string of the 16-byte IV. 4752 4753 The simplest (insecure) usage is to provide the secret inline 4754 4755 .. parsed-literal:: 4756 4757 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw 4758 4759 The simplest secure usage is to provide the secret via a file 4760 4761 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object 4762 secret,id=sec0,file=mypasswd.txt,format=raw 4763 4764 For greater security, AES-256-CBC should be used. To illustrate 4765 usage, consider the openssl command line tool which can encrypt 4766 the data. Note that when encrypting, the plaintext must be 4767 padded to the cipher block size (32 bytes) using the standard 4768 PKCS#5/6 compatible padding algorithm. 4769 4770 First a master key needs to be created in base64 encoding: 4771 4772 :: 4773 4774 # openssl rand -base64 32 > key.b64 4775 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"') 4776 4777 Each secret to be encrypted needs to have a random 4778 initialization vector generated. These do not need to be kept 4779 secret 4780 4781 :: 4782 4783 # openssl rand -base64 16 > iv.b64 4784 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"') 4785 4786 The secret to be defined can now be encrypted, in this case 4787 we're telling openssl to base64 encode the result, but it could 4788 be left as raw bytes if desired. 4789 4790 :: 4791 4792 # SECRET=$(printf "letmein" | 4793 openssl enc -aes-256-cbc -a -K $KEY -iv $IV) 4794 4795 When launching QEMU, create a master secret pointing to 4796 ``key.b64`` and specify that to be used to decrypt the user 4797 password. Pass the contents of ``iv.b64`` to the second secret 4798 4799 .. parsed-literal:: 4800 4801 # |qemu_system| \ 4802 -object secret,id=secmaster0,format=base64,file=key.b64 \ 4803 -object secret,id=sec0,keyid=secmaster0,format=base64,\ 4804 data=$SECRET,iv=$(<iv.b64) 4805 4806 ``-object sev-guest,id=id,cbitpos=cbitpos,reduced-phys-bits=val,[sev-device=string,policy=policy,handle=handle,dh-cert-file=file,session-file=file]`` 4807 Create a Secure Encrypted Virtualization (SEV) guest object, 4808 which can be used to provide the guest memory encryption support 4809 on AMD processors. 4810 4811 When memory encryption is enabled, one of the physical address 4812 bit (aka the C-bit) is utilized to mark if a memory page is 4813 protected. The ``cbitpos`` is used to provide the C-bit 4814 position. The C-bit position is Host family dependent hence user 4815 must provide this value. On EPYC, the value should be 47. 4816 4817 When memory encryption is enabled, we loose certain bits in 4818 physical address space. The ``reduced-phys-bits`` is used to 4819 provide the number of bits we loose in physical address space. 4820 Similar to C-bit, the value is Host family dependent. On EPYC, 4821 the value should be 5. 4822 4823 The ``sev-device`` provides the device file to use for 4824 communicating with the SEV firmware running inside AMD Secure 4825 Processor. The default device is '/dev/sev'. If hardware 4826 supports memory encryption then /dev/sev devices are created by 4827 CCP driver. 4828 4829 The ``policy`` provides the guest policy to be enforced by the 4830 SEV firmware and restrict what configuration and operational 4831 commands can be performed on this guest by the hypervisor. The 4832 policy should be provided by the guest owner and is bound to the 4833 guest and cannot be changed throughout the lifetime of the 4834 guest. The default is 0. 4835 4836 If guest ``policy`` allows sharing the key with another SEV 4837 guest then ``handle`` can be use to provide handle of the guest 4838 from which to share the key. 4839 4840 The ``dh-cert-file`` and ``session-file`` provides the guest 4841 owner's Public Diffie-Hillman key defined in SEV spec. The PDH 4842 and session parameters are used for establishing a cryptographic 4843 session with the guest owner to negotiate keys used for 4844 attestation. The file must be encoded in base64. 4845 4846 e.g to launch a SEV guest 4847 4848 .. parsed-literal:: 4849 4850 # |qemu_system_x86| \ 4851 ...... 4852 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \ 4853 -machine ...,memory-encryption=sev0 4854 ..... 4855 4856 ``-object authz-simple,id=id,identity=string`` 4857 Create an authorization object that will control access to 4858 network services. 4859 4860 The ``identity`` parameter is identifies the user and its format 4861 depends on the network service that authorization object is 4862 associated with. For authorizing based on TLS x509 certificates, 4863 the identity must be the x509 distinguished name. Note that care 4864 must be taken to escape any commas in the distinguished name. 4865 4866 An example authorization object to validate a x509 distinguished 4867 name would look like: 4868 4869 .. parsed-literal:: 4870 4871 # |qemu_system| \ 4872 ... 4873 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \ 4874 ... 4875 4876 Note the use of quotes due to the x509 distinguished name 4877 containing whitespace, and escaping of ','. 4878 4879 ``-object authz-listfile,id=id,filename=path,refresh=yes|no`` 4880 Create an authorization object that will control access to 4881 network services. 4882 4883 The ``filename`` parameter is the fully qualified path to a file 4884 containing the access control list rules in JSON format. 4885 4886 An example set of rules that match against SASL usernames might 4887 look like: 4888 4889 :: 4890 4891 { 4892 "rules": [ 4893 { "match": "fred", "policy": "allow", "format": "exact" }, 4894 { "match": "bob", "policy": "allow", "format": "exact" }, 4895 { "match": "danb", "policy": "deny", "format": "glob" }, 4896 { "match": "dan*", "policy": "allow", "format": "exact" }, 4897 ], 4898 "policy": "deny" 4899 } 4900 4901 When checking access the object will iterate over all the rules 4902 and the first rule to match will have its ``policy`` value 4903 returned as the result. If no rules match, then the default 4904 ``policy`` value is returned. 4905 4906 The rules can either be an exact string match, or they can use 4907 the simple UNIX glob pattern matching to allow wildcards to be 4908 used. 4909 4910 If ``refresh`` is set to true the file will be monitored and 4911 automatically reloaded whenever its content changes. 4912 4913 As with the ``authz-simple`` object, the format of the identity 4914 strings being matched depends on the network service, but is 4915 usually a TLS x509 distinguished name, or a SASL username. 4916 4917 An example authorization object to validate a SASL username 4918 would look like: 4919 4920 .. parsed-literal:: 4921 4922 # |qemu_system| \ 4923 ... 4924 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=yes 4925 ... 4926 4927 ``-object authz-pam,id=id,service=string`` 4928 Create an authorization object that will control access to 4929 network services. 4930 4931 The ``service`` parameter provides the name of a PAM service to 4932 use for authorization. It requires that a file 4933 ``/etc/pam.d/service`` exist to provide the configuration for 4934 the ``account`` subsystem. 4935 4936 An example authorization object to validate a TLS x509 4937 distinguished name would look like: 4938 4939 .. parsed-literal:: 4940 4941 # |qemu_system| \ 4942 ... 4943 -object authz-pam,id=auth0,service=qemu-vnc 4944 ... 4945 4946 There would then be a corresponding config file for PAM at 4947 ``/etc/pam.d/qemu-vnc`` that contains: 4948 4949 :: 4950 4951 account requisite pam_listfile.so item=user sense=allow \ 4952 file=/etc/qemu/vnc.allow 4953 4954 Finally the ``/etc/qemu/vnc.allow`` file would contain the list 4955 of x509 distingished names that are permitted access 4956 4957 :: 4958 4959 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB 4960 4961 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink`` 4962 Creates a dedicated event loop thread that devices can be 4963 assigned to. This is known as an IOThread. By default device 4964 emulation happens in vCPU threads or the main event loop thread. 4965 This can become a scalability bottleneck. IOThreads allow device 4966 emulation and I/O to run on other host CPUs. 4967 4968 The ``id`` parameter is a unique ID that will be used to 4969 reference this IOThread from ``-device ...,iothread=id``. 4970 Multiple devices can be assigned to an IOThread. Note that not 4971 all devices support an ``iothread`` parameter. 4972 4973 The ``query-iothreads`` QMP command lists IOThreads and reports 4974 their thread IDs so that the user can configure host CPU 4975 pinning/affinity. 4976 4977 IOThreads use an adaptive polling algorithm to reduce event loop 4978 latency. Instead of entering a blocking system call to monitor 4979 file descriptors and then pay the cost of being woken up when an 4980 event occurs, the polling algorithm spins waiting for events for 4981 a short time. The algorithm's default parameters are suitable 4982 for many cases but can be adjusted based on knowledge of the 4983 workload and/or host device latency. 4984 4985 The ``poll-max-ns`` parameter is the maximum number of 4986 nanoseconds to busy wait for events. Polling can be disabled by 4987 setting this value to 0. 4988 4989 The ``poll-grow`` parameter is the multiplier used to increase 4990 the polling time when the algorithm detects it is missing events 4991 due to not polling long enough. 4992 4993 The ``poll-shrink`` parameter is the divisor used to decrease 4994 the polling time when the algorithm detects it is spending too 4995 long polling without encountering events. 4996 4997 The polling parameters can be modified at run-time using the 4998 ``qom-set`` command (where ``iothread1`` is the IOThread's 4999 ``id``): 5000 5001 :: 5002 5003 (qemu) qom-set /objects/iothread1 poll-max-ns 100000 5004ERST 5005 5006 5007HXCOMM This is the last statement. Insert new options before this line! 5008
