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, nvmm, whpx or tcg (default: tcg)\n" 30 " vmport=on|off|auto controls emulation of vmport (default: auto)\n" 31 " dump-guest-core=on|off include guest memory in a core dump (default=on)\n" 32 " mem-merge=on|off controls memory merge support (default: on)\n" 33 " aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n" 34 " dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n" 35 " suppress-vmdesc=on|off disables self-describing migration (default=off)\n" 36 " nvdimm=on|off controls NVDIMM support (default=off)\n" 37 " memory-encryption=@var{} memory encryption object to use (default=none)\n" 38 " hmat=on|off controls ACPI HMAT support (default=off)\n" 39 " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n", 40 QEMU_ARCH_ALL) 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, nvmm, 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 ``memory-encryption=`` 95 Memory encryption object to use. The default is none. 96 97 ``hmat=on|off`` 98 Enables or disables ACPI Heterogeneous Memory Attribute Table 99 (HMAT) support. The default is off. 100 101 ``memory-backend='id'`` 102 An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options. 103 Allows to use a memory backend as main RAM. 104 105 For example: 106 :: 107 108 -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on 109 -machine memory-backend=pc.ram 110 -m 512M 111 112 Migration compatibility note: 113 114 * as backend id one shall use value of 'default-ram-id', advertised by 115 machine type (available via ``query-machines`` QMP command), if migration 116 to/from old QEMU (<5.0) is expected. 117 * for machine types 4.0 and older, user shall 118 use ``x-use-canonical-path-for-ramblock-id=off`` backend option 119 if migration to/from old QEMU (<5.0) is expected. 120 121 For example: 122 :: 123 124 -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off 125 -machine memory-backend=pc.ram 126 -m 512M 127ERST 128 129DEF("M", HAS_ARG, QEMU_OPTION_M, 130 " sgx-epc.0.memdev=memid\n", 131 QEMU_ARCH_ALL) 132 133SRST 134``sgx-epc.0.memdev=@var{memid}`` 135 Define an SGX EPC section. 136ERST 137 138DEF("cpu", HAS_ARG, QEMU_OPTION_cpu, 139 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL) 140SRST 141``-cpu model`` 142 Select CPU model (``-cpu help`` for list and additional feature 143 selection) 144ERST 145 146DEF("accel", HAS_ARG, QEMU_OPTION_accel, 147 "-accel [accel=]accelerator[,prop[=value][,...]]\n" 148 " select accelerator (kvm, xen, hax, hvf, nvmm, whpx or tcg; use 'help' for a list)\n" 149 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n" 150 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n" 151 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n" 152 " split-wx=on|off (enable TCG split w^x mapping)\n" 153 " tb-size=n (TCG translation block cache size)\n" 154 " dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n" 155 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL) 156SRST 157``-accel name[,prop=value[,...]]`` 158 This is used to enable an accelerator. Depending on the target 159 architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available. By 160 default, tcg is used. If there is more than one accelerator 161 specified, the next one is used if the previous one fails to 162 initialize. 163 164 ``igd-passthru=on|off`` 165 When Xen is in use, this option controls whether Intel 166 integrated graphics devices can be passed through to the guest 167 (default=off) 168 169 ``kernel-irqchip=on|off|split`` 170 Controls KVM in-kernel irqchip support. The default is full 171 acceleration of the interrupt controllers. On x86, split irqchip 172 reduces the kernel attack surface, at a performance cost for 173 non-MSI interrupts. Disabling the in-kernel irqchip completely 174 is not recommended except for debugging purposes. 175 176 ``kvm-shadow-mem=size`` 177 Defines the size of the KVM shadow MMU. 178 179 ``split-wx=on|off`` 180 Controls the use of split w^x mapping for the TCG code generation 181 buffer. Some operating systems require this to be enabled, and in 182 such a case this will default on. On other operating systems, this 183 will default off, but one may enable this for testing or debugging. 184 185 ``tb-size=n`` 186 Controls the size (in MiB) of the TCG translation block cache. 187 188 ``thread=single|multi`` 189 Controls number of TCG threads. When the TCG is multi-threaded 190 there will be one thread per vCPU therefore taking advantage of 191 additional host cores. The default is to enable multi-threading 192 where both the back-end and front-ends support it and no 193 incompatible TCG features have been enabled (e.g. 194 icount/replay). 195 196 ``dirty-ring-size=n`` 197 When the KVM accelerator is used, it controls the size of the per-vCPU 198 dirty page ring buffer (number of entries for each vCPU). It should 199 be a value that is power of two, and it should be 1024 or bigger (but 200 still less than the maximum value that the kernel supports). 4096 201 could be a good initial value if you have no idea which is the best. 202 Set this value to 0 to disable the feature. By default, this feature 203 is disabled (dirty-ring-size=0). When enabled, KVM will instead 204 record dirty pages in a bitmap. 205 206ERST 207 208DEF("smp", HAS_ARG, QEMU_OPTION_smp, 209 "-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,cores=cores][,threads=threads]\n" 210 " set the number of CPUs to 'n' [default=1]\n" 211 " maxcpus= maximum number of total CPUs, including\n" 212 " offline CPUs for hotplug, etc\n" 213 " sockets= number of discrete sockets in the system\n" 214 " dies= number of CPU dies on one socket (for PC only)\n" 215 " cores= number of CPU cores on one socket (for PC, it's on one die)\n" 216 " threads= number of threads on one CPU core\n", 217 QEMU_ARCH_ALL) 218SRST 219``-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,cores=cores][,threads=threads]`` 220 Simulate a SMP system with '\ ``n``\ ' CPUs initially present on 221 the machine type board. On boards supporting CPU hotplug, the optional 222 '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be 223 added at runtime. When both parameters are omitted, the maximum number 224 of CPUs will be calculated from the provided topology members and the 225 initial CPU count will match the maximum number. When only one of them 226 is given then the omitted one will be set to its counterpart's value. 227 Both parameters may be specified, but the maximum number of CPUs must 228 be equal to or greater than the initial CPU count. Both parameters are 229 subject to an upper limit that is determined by the specific machine 230 type chosen. 231 232 To control reporting of CPU topology information, the number of sockets, 233 dies per socket, cores per die, and threads per core can be specified. 234 The sum `` sockets * cores * dies * threads `` must be equal to the 235 maximum CPU count. CPU targets may only support a subset of the topology 236 parameters. Where a CPU target does not support use of a particular 237 topology parameter, its value should be assumed to be 1 for the purpose 238 of computing the CPU maximum count. 239 240 Either the initial CPU count, or at least one of the topology parameters 241 must be specified. The specified parameters must be greater than zero, 242 explicit configuration like "cpus=0" is not allowed. Values for any 243 omitted parameters will be computed from those which are given. 244 Historically preference was given to the coarsest topology parameters 245 when computing missing values (ie sockets preferred over cores, which 246 were preferred over threads), however, this behaviour is considered 247 liable to change. Prior to 6.2 the preference was sockets over cores 248 over threads. Since 6.2 the preference is cores over sockets over threads. 249ERST 250 251DEF("numa", HAS_ARG, QEMU_OPTION_numa, 252 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 253 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 254 "-numa dist,src=source,dst=destination,val=distance\n" 255 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n" 256 "-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" 257 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n", 258 QEMU_ARCH_ALL) 259SRST 260``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 261 \ 262``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 263 \ 264``-numa dist,src=source,dst=destination,val=distance`` 265 \ 266``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]`` 267 \ 268``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]`` 269 \ 270``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]`` 271 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA 272 distance from a source node to a destination node. Set the ACPI 273 Heterogeneous Memory Attributes for the given nodes. 274 275 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and 276 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a 277 contiguous range of CPU indexes (or a single VCPU if lastcpu is 278 omitted). A non-contiguous set of VCPUs can be represented by 279 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is 280 omitted on all nodes, VCPUs are automatically split between them. 281 282 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a 283 NUMA node: 284 285 :: 286 287 -numa node,cpus=0-2,cpus=5 288 289 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option 290 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to 291 assign CPU objects to a node using topology layout properties of 292 CPU. The set of properties is machine specific, and depends on used 293 machine type/'\ ``smp``\ ' options. It could be queried with 294 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ ' 295 property specifies node to which CPU object will be assigned, it's 296 required for node to be declared with '\ ``node``\ ' option before 297 it's used with '\ ``cpu``\ ' option. 298 299 For example: 300 301 :: 302 303 -M pc \ 304 -smp 1,sockets=2,maxcpus=2 \ 305 -numa node,nodeid=0 -numa node,nodeid=1 \ 306 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1 307 308 Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported 309 for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from 310 a given memory backend device to a node. If '\ ``mem``\ ' and 311 '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them. 312 313 314 '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive. 315 Furthermore, if one node uses '\ ``memdev``\ ', all of them have to 316 use it. 317 318 '\ ``initiator``\ ' is an additional option that points to an 319 initiator NUMA node that has best performance (the lowest latency or 320 largest bandwidth) to this NUMA node. Note that this option can be 321 set only when the machine property 'hmat' is set to 'on'. 322 323 Following example creates a machine with 2 NUMA nodes, node 0 has 324 CPU. node 1 has only memory, and its initiator is node 0. Note that 325 because node 0 has CPU, by default the initiator of node 0 is itself 326 and must be itself. 327 328 :: 329 330 -machine hmat=on \ 331 -m 2G,slots=2,maxmem=4G \ 332 -object memory-backend-ram,size=1G,id=m0 \ 333 -object memory-backend-ram,size=1G,id=m1 \ 334 -numa node,nodeid=0,memdev=m0 \ 335 -numa node,nodeid=1,memdev=m1,initiator=0 \ 336 -smp 2,sockets=2,maxcpus=2 \ 337 -numa cpu,node-id=0,socket-id=0 \ 338 -numa cpu,node-id=0,socket-id=1 339 340 source and destination are NUMA node IDs. distance is the NUMA 341 distance from source to destination. The distance from a node to 342 itself is always 10. If any pair of nodes is given a distance, then 343 all pairs must be given distances. Although, when distances are only 344 given in one direction for each pair of nodes, then the distances in 345 the opposite directions are assumed to be the same. If, however, an 346 asymmetrical pair of distances is given for even one node pair, then 347 all node pairs must be provided distance values for both directions, 348 even when they are symmetrical. When a node is unreachable from 349 another node, set the pair's distance to 255. 350 351 Note that the -``numa`` option doesn't allocate any of the specified 352 resources, it just assigns existing resources to NUMA nodes. This 353 means that one still has to use the ``-m``, ``-smp`` options to 354 allocate RAM and VCPUs respectively. 355 356 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth 357 Information between initiator and target NUMA nodes in ACPI 358 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can 359 create memory requests, usually it has one or more processors. 360 Target NUMA node contains addressable memory. 361 362 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is 363 the memory hierarchy of the target NUMA node: if hierarchy is 364 'memory', the structure represents the memory performance; if 365 hierarchy is 'first-level\|second-level\|third-level', this 366 structure represents aggregated performance of memory side caches 367 for each domain. type of 'data-type' is type of data represented by 368 this structure instance: if 'hierarchy' is 'memory', 'data-type' is 369 'access\|read\|write' latency or 'access\|read\|write' bandwidth of 370 the target memory; if 'hierarchy' is 371 'first-level\|second-level\|third-level', 'data-type' is 372 'access\|read\|write' hit latency or 'access\|read\|write' hit 373 bandwidth of the target memory side cache. 374 375 lat is latency value in nanoseconds. bw is bandwidth value, the 376 possible value and units are NUM[M\|G\|T], mean that the bandwidth 377 value are NUM byte per second (or MB/s, GB/s or TB/s depending on 378 used suffix). Note that if latency or bandwidth value is 0, means 379 the corresponding latency or bandwidth information is not provided. 380 381 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory 382 belongs. size is the size of memory side cache in bytes. level is 383 the cache level described in this structure, note that the cache 384 level 0 should not be used with '\ ``hmat-cache``\ ' option. 385 associativity is the cache associativity, the possible value is 386 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy 387 is the write policy. line is the cache Line size in bytes. 388 389 For example, the following options describe 2 NUMA nodes. Node 0 has 390 2 cpus and a ram, node 1 has only a ram. The processors in node 0 391 access memory in node 0 with access-latency 5 nanoseconds, 392 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access 393 memory in NUMA node 1 with access-latency 10 nanoseconds, 394 access-bandwidth is 100 MB/s. And for memory side cache information, 395 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB, 396 policy is write-back, the cache Line size is 8 bytes: 397 398 :: 399 400 -machine hmat=on \ 401 -m 2G \ 402 -object memory-backend-ram,size=1G,id=m0 \ 403 -object memory-backend-ram,size=1G,id=m1 \ 404 -smp 2,sockets=2,maxcpus=2 \ 405 -numa node,nodeid=0,memdev=m0 \ 406 -numa node,nodeid=1,memdev=m1,initiator=0 \ 407 -numa cpu,node-id=0,socket-id=0 \ 408 -numa cpu,node-id=0,socket-id=1 \ 409 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \ 410 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \ 411 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \ 412 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \ 413 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \ 414 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8 415ERST 416 417DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd, 418 "-add-fd fd=fd,set=set[,opaque=opaque]\n" 419 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL) 420SRST 421``-add-fd fd=fd,set=set[,opaque=opaque]`` 422 Add a file descriptor to an fd set. Valid options are: 423 424 ``fd=fd`` 425 This option defines the file descriptor of which a duplicate is 426 added to fd set. The file descriptor cannot be stdin, stdout, or 427 stderr. 428 429 ``set=set`` 430 This option defines the ID of the fd set to add the file 431 descriptor to. 432 433 ``opaque=opaque`` 434 This option defines a free-form string that can be used to 435 describe fd. 436 437 You can open an image using pre-opened file descriptors from an fd 438 set: 439 440 .. parsed-literal:: 441 442 |qemu_system| \\ 443 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 444 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 445 -drive file=/dev/fdset/2,index=0,media=disk 446ERST 447 448DEF("set", HAS_ARG, QEMU_OPTION_set, 449 "-set group.id.arg=value\n" 450 " set <arg> parameter for item <id> of type <group>\n" 451 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL) 452SRST 453``-set group.id.arg=value`` 454 Set parameter arg for item id of type group 455ERST 456 457DEF("global", HAS_ARG, QEMU_OPTION_global, 458 "-global driver.property=value\n" 459 "-global driver=driver,property=property,value=value\n" 460 " set a global default for a driver property\n", 461 QEMU_ARCH_ALL) 462SRST 463``-global driver.prop=value`` 464 \ 465``-global driver=driver,property=property,value=value`` 466 Set default value of driver's property prop to value, e.g.: 467 468 .. parsed-literal:: 469 470 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img 471 472 In particular, you can use this to set driver properties for devices 473 which are created automatically by the machine model. To create a 474 device which is not created automatically and set properties on it, 475 use -``device``. 476 477 -global driver.prop=value is shorthand for -global 478 driver=driver,property=prop,value=value. The longhand syntax works 479 even when driver contains a dot. 480ERST 481 482DEF("boot", HAS_ARG, QEMU_OPTION_boot, 483 "-boot [order=drives][,once=drives][,menu=on|off]\n" 484 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n" 485 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n" 486 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n" 487 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n" 488 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n", 489 QEMU_ARCH_ALL) 490SRST 491``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]`` 492 Specify boot order drives as a string of drive letters. Valid drive 493 letters depend on the target architecture. The x86 PC uses: a, b 494 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p 495 (Etherboot from network adapter 1-4), hard disk boot is the default. 496 To apply a particular boot order only on the first startup, specify 497 it via ``once``. Note that the ``order`` or ``once`` parameter 498 should not be used together with the ``bootindex`` property of 499 devices, since the firmware implementations normally do not support 500 both at the same time. 501 502 Interactive boot menus/prompts can be enabled via ``menu=on`` as far 503 as firmware/BIOS supports them. The default is non-interactive boot. 504 505 A splash picture could be passed to bios, enabling user to show it 506 as logo, when option splash=sp\_name is given and menu=on, If 507 firmware/BIOS supports them. Currently Seabios for X86 system 508 support it. limitation: The splash file could be a jpeg file or a 509 BMP file in 24 BPP format(true color). The resolution should be 510 supported by the SVGA mode, so the recommended is 320x240, 640x480, 511 800x640. 512 513 A timeout could be passed to bios, guest will pause for rb\_timeout 514 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will 515 not reboot, qemu passes '-1' to bios by default. Currently Seabios 516 for X86 system support it. 517 518 Do strict boot via ``strict=on`` as far as firmware/BIOS supports 519 it. This only effects when boot priority is changed by bootindex 520 options. The default is non-strict boot. 521 522 .. parsed-literal:: 523 524 # try to boot from network first, then from hard disk 525 |qemu_system_x86| -boot order=nc 526 # boot from CD-ROM first, switch back to default order after reboot 527 |qemu_system_x86| -boot once=d 528 # boot with a splash picture for 5 seconds. 529 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000 530 531 Note: The legacy format '-boot drives' is still supported but its 532 use is discouraged as it may be removed from future versions. 533ERST 534 535DEF("m", HAS_ARG, QEMU_OPTION_m, 536 "-m [size=]megs[,slots=n,maxmem=size]\n" 537 " configure guest RAM\n" 538 " size: initial amount of guest memory\n" 539 " slots: number of hotplug slots (default: none)\n" 540 " maxmem: maximum amount of guest memory (default: none)\n" 541 "NOTE: Some architectures might enforce a specific granularity\n", 542 QEMU_ARCH_ALL) 543SRST 544``-m [size=]megs[,slots=n,maxmem=size]`` 545 Sets guest startup RAM size to megs megabytes. Default is 128 MiB. 546 Optionally, a suffix of "M" or "G" can be used to signify a value in 547 megabytes or gigabytes respectively. Optional pair slots, maxmem 548 could be used to set amount of hotpluggable memory slots and maximum 549 amount of memory. Note that maxmem must be aligned to the page size. 550 551 For example, the following command-line sets the guest startup RAM 552 size to 1GB, creates 3 slots to hotplug additional memory and sets 553 the maximum memory the guest can reach to 4GB: 554 555 .. parsed-literal:: 556 557 |qemu_system| -m 1G,slots=3,maxmem=4G 558 559 If slots and maxmem are not specified, memory hotplug won't be 560 enabled and the guest startup RAM will never increase. 561ERST 562 563DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath, 564 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL) 565SRST 566``-mem-path path`` 567 Allocate guest RAM from a temporarily created file in path. 568ERST 569 570DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc, 571 "-mem-prealloc preallocate guest memory (use with -mem-path)\n", 572 QEMU_ARCH_ALL) 573SRST 574``-mem-prealloc`` 575 Preallocate memory when using -mem-path. 576ERST 577 578DEF("k", HAS_ARG, QEMU_OPTION_k, 579 "-k language use keyboard layout (for example 'fr' for French)\n", 580 QEMU_ARCH_ALL) 581SRST 582``-k language`` 583 Use keyboard layout language (for example ``fr`` for French). This 584 option is only needed where it is not easy to get raw PC keycodes 585 (e.g. on Macs, with some X11 servers or with a VNC or curses 586 display). You don't normally need to use it on PC/Linux or 587 PC/Windows hosts. 588 589 The available layouts are: 590 591 :: 592 593 ar de-ch es fo fr-ca hu ja mk no pt-br sv 594 da en-gb et fr fr-ch is lt nl pl ru th 595 de en-us fi fr-be hr it lv nl-be pt sl tr 596 597 The default is ``en-us``. 598ERST 599 600 601HXCOMM Deprecated by -audiodev 602DEF("audio-help", 0, QEMU_OPTION_audio_help, 603 "-audio-help show -audiodev equivalent of the currently specified audio settings\n", 604 QEMU_ARCH_ALL) 605SRST 606``-audio-help`` 607 Will show the -audiodev equivalent of the currently specified 608 (deprecated) environment variables. 609ERST 610 611DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev, 612 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n" 613 " specifies the audio backend to use\n" 614 " id= identifier of the backend\n" 615 " timer-period= timer period in microseconds\n" 616 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n" 617 " in|out.fixed-settings= use fixed settings for host audio\n" 618 " in|out.frequency= frequency to use with fixed settings\n" 619 " in|out.channels= number of channels to use with fixed settings\n" 620 " in|out.format= sample format to use with fixed settings\n" 621 " valid values: s8, s16, s32, u8, u16, u32, f32\n" 622 " in|out.voices= number of voices to use\n" 623 " in|out.buffer-length= length of buffer in microseconds\n" 624 "-audiodev none,id=id,[,prop[=value][,...]]\n" 625 " dummy driver that discards all output\n" 626#ifdef CONFIG_AUDIO_ALSA 627 "-audiodev alsa,id=id[,prop[=value][,...]]\n" 628 " in|out.dev= name of the audio device to use\n" 629 " in|out.period-length= length of period in microseconds\n" 630 " in|out.try-poll= attempt to use poll mode\n" 631 " threshold= threshold (in microseconds) when playback starts\n" 632#endif 633#ifdef CONFIG_AUDIO_COREAUDIO 634 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n" 635 " in|out.buffer-count= number of buffers\n" 636#endif 637#ifdef CONFIG_AUDIO_DSOUND 638 "-audiodev dsound,id=id[,prop[=value][,...]]\n" 639 " latency= add extra latency to playback in microseconds\n" 640#endif 641#ifdef CONFIG_AUDIO_OSS 642 "-audiodev oss,id=id[,prop[=value][,...]]\n" 643 " in|out.dev= path of the audio device to use\n" 644 " in|out.buffer-count= number of buffers\n" 645 " in|out.try-poll= attempt to use poll mode\n" 646 " try-mmap= try using memory mapped access\n" 647 " exclusive= open device in exclusive mode\n" 648 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n" 649#endif 650#ifdef CONFIG_AUDIO_PA 651 "-audiodev pa,id=id[,prop[=value][,...]]\n" 652 " server= PulseAudio server address\n" 653 " in|out.name= source/sink device name\n" 654 " in|out.latency= desired latency in microseconds\n" 655#endif 656#ifdef CONFIG_AUDIO_SDL 657 "-audiodev sdl,id=id[,prop[=value][,...]]\n" 658 " in|out.buffer-count= number of buffers\n" 659#endif 660#ifdef CONFIG_SPICE 661 "-audiodev spice,id=id[,prop[=value][,...]]\n" 662#endif 663 "-audiodev wav,id=id[,prop[=value][,...]]\n" 664 " path= path of wav file to record\n", 665 QEMU_ARCH_ALL) 666SRST 667``-audiodev [driver=]driver,id=id[,prop[=value][,...]]`` 668 Adds a new audio backend driver identified by id. There are global 669 and driver specific properties. Some values can be set differently 670 for input and output, they're marked with ``in|out.``. You can set 671 the input's property with ``in.prop`` and the output's property with 672 ``out.prop``. For example: 673 674 :: 675 676 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000 677 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified 678 679 NOTE: parameter validation is known to be incomplete, in many cases 680 specifying an invalid option causes QEMU to print an error message 681 and continue emulation without sound. 682 683 Valid global options are: 684 685 ``id=identifier`` 686 Identifies the audio backend. 687 688 ``timer-period=period`` 689 Sets the timer period used by the audio subsystem in 690 microseconds. Default is 10000 (10 ms). 691 692 ``in|out.mixing-engine=on|off`` 693 Use QEMU's mixing engine to mix all streams inside QEMU and 694 convert audio formats when not supported by the backend. When 695 off, fixed-settings must be off too. Note that disabling this 696 option means that the selected backend must support multiple 697 streams and the audio formats used by the virtual cards, 698 otherwise you'll get no sound. It's not recommended to disable 699 this option unless you want to use 5.1 or 7.1 audio, as mixing 700 engine only supports mono and stereo audio. Default is on. 701 702 ``in|out.fixed-settings=on|off`` 703 Use fixed settings for host audio. When off, it will change 704 based on how the guest opens the sound card. In this case you 705 must not specify frequency, channels or format. Default is on. 706 707 ``in|out.frequency=frequency`` 708 Specify the frequency to use when using fixed-settings. Default 709 is 44100Hz. 710 711 ``in|out.channels=channels`` 712 Specify the number of channels to use when using fixed-settings. 713 Default is 2 (stereo). 714 715 ``in|out.format=format`` 716 Specify the sample format to use when using fixed-settings. 717 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``, 718 ``u32``, ``f32``. Default is ``s16``. 719 720 ``in|out.voices=voices`` 721 Specify the number of voices to use. Default is 1. 722 723 ``in|out.buffer-length=usecs`` 724 Sets the size of the buffer in microseconds. 725 726``-audiodev none,id=id[,prop[=value][,...]]`` 727 Creates a dummy backend that discards all outputs. This backend has 728 no backend specific properties. 729 730``-audiodev alsa,id=id[,prop[=value][,...]]`` 731 Creates backend using the ALSA. This backend is only available on 732 Linux. 733 734 ALSA specific options are: 735 736 ``in|out.dev=device`` 737 Specify the ALSA device to use for input and/or output. Default 738 is ``default``. 739 740 ``in|out.period-length=usecs`` 741 Sets the period length in microseconds. 742 743 ``in|out.try-poll=on|off`` 744 Attempt to use poll mode with the device. Default is on. 745 746 ``threshold=threshold`` 747 Threshold (in microseconds) when playback starts. Default is 0. 748 749``-audiodev coreaudio,id=id[,prop[=value][,...]]`` 750 Creates a backend using Apple's Core Audio. This backend is only 751 available on Mac OS and only supports playback. 752 753 Core Audio specific options are: 754 755 ``in|out.buffer-count=count`` 756 Sets the count of the buffers. 757 758``-audiodev dsound,id=id[,prop[=value][,...]]`` 759 Creates a backend using Microsoft's DirectSound. This backend is 760 only available on Windows and only supports playback. 761 762 DirectSound specific options are: 763 764 ``latency=usecs`` 765 Add extra usecs microseconds latency to playback. Default is 766 10000 (10 ms). 767 768``-audiodev oss,id=id[,prop[=value][,...]]`` 769 Creates a backend using OSS. This backend is available on most 770 Unix-like systems. 771 772 OSS specific options are: 773 774 ``in|out.dev=device`` 775 Specify the file name of the OSS device to use. Default is 776 ``/dev/dsp``. 777 778 ``in|out.buffer-count=count`` 779 Sets the count of the buffers. 780 781 ``in|out.try-poll=on|of`` 782 Attempt to use poll mode with the device. Default is on. 783 784 ``try-mmap=on|off`` 785 Try using memory mapped device access. Default is off. 786 787 ``exclusive=on|off`` 788 Open the device in exclusive mode (vmix won't work in this 789 case). Default is off. 790 791 ``dsp-policy=policy`` 792 Sets the timing policy (between 0 and 10, where smaller number 793 means smaller latency but higher CPU usage). Use -1 to use 794 buffer sizes specified by ``buffer`` and ``buffer-count``. This 795 option is ignored if you do not have OSS 4. Default is 5. 796 797``-audiodev pa,id=id[,prop[=value][,...]]`` 798 Creates a backend using PulseAudio. This backend is available on 799 most systems. 800 801 PulseAudio specific options are: 802 803 ``server=server`` 804 Sets the PulseAudio server to connect to. 805 806 ``in|out.name=sink`` 807 Use the specified source/sink for recording/playback. 808 809 ``in|out.latency=usecs`` 810 Desired latency in microseconds. The PulseAudio server will try 811 to honor this value but actual latencies may be lower or higher. 812 813``-audiodev sdl,id=id[,prop[=value][,...]]`` 814 Creates a backend using SDL. This backend is available on most 815 systems, but you should use your platform's native backend if 816 possible. 817 818 SDL specific options are: 819 820 ``in|out.buffer-count=count`` 821 Sets the count of the buffers. 822 823``-audiodev spice,id=id[,prop[=value][,...]]`` 824 Creates a backend that sends audio through SPICE. This backend 825 requires ``-spice`` and automatically selected in that case, so 826 usually you can ignore this option. This backend has no backend 827 specific properties. 828 829``-audiodev wav,id=id[,prop[=value][,...]]`` 830 Creates a backend that writes audio to a WAV file. 831 832 Backend specific options are: 833 834 ``path=path`` 835 Write recorded audio into the specified file. Default is 836 ``qemu.wav``. 837ERST 838 839DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw, 840 "-soundhw c1,... enable audio support\n" 841 " and only specified sound cards (comma separated list)\n" 842 " use '-soundhw help' to get the list of supported cards\n" 843 " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL) 844SRST 845``-soundhw card1[,card2,...] or -soundhw all`` 846 Enable audio and selected sound hardware. Use 'help' to print all 847 available sound hardware. For example: 848 849 .. parsed-literal:: 850 851 |qemu_system_x86| -soundhw sb16,adlib disk.img 852 |qemu_system_x86| -soundhw es1370 disk.img 853 |qemu_system_x86| -soundhw ac97 disk.img 854 |qemu_system_x86| -soundhw hda disk.img 855 |qemu_system_x86| -soundhw all disk.img 856 |qemu_system_x86| -soundhw help 857 858 Note that Linux's i810\_audio OSS kernel (for AC97) module might 859 require manually specifying clocking. 860 861 :: 862 863 modprobe i810_audio clocking=48000 864ERST 865 866DEF("device", HAS_ARG, QEMU_OPTION_device, 867 "-device driver[,prop[=value][,...]]\n" 868 " add device (based on driver)\n" 869 " prop=value,... sets driver properties\n" 870 " use '-device help' to print all possible drivers\n" 871 " use '-device driver,help' to print all possible properties\n", 872 QEMU_ARCH_ALL) 873SRST 874``-device driver[,prop[=value][,...]]`` 875 Add device driver. prop=value sets driver properties. Valid 876 properties depend on the driver. To get help on possible drivers and 877 properties, use ``-device help`` and ``-device driver,help``. 878 879 Some drivers are: 880 881``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]`` 882 Add an IPMI BMC. This is a simulation of a hardware management 883 interface processor that normally sits on a system. It provides a 884 watchdog and the ability to reset and power control the system. You 885 need to connect this to an IPMI interface to make it useful 886 887 The IPMI slave address to use for the BMC. The default is 0x20. This 888 address is the BMC's address on the I2C network of management 889 controllers. If you don't know what this means, it is safe to ignore 890 it. 891 892 ``id=id`` 893 The BMC id for interfaces to use this device. 894 895 ``slave_addr=val`` 896 Define slave address to use for the BMC. The default is 0x20. 897 898 ``sdrfile=file`` 899 file containing raw Sensor Data Records (SDR) data. The default 900 is none. 901 902 ``fruareasize=val`` 903 size of a Field Replaceable Unit (FRU) area. The default is 904 1024. 905 906 ``frudatafile=file`` 907 file containing raw Field Replaceable Unit (FRU) inventory data. 908 The default is none. 909 910 ``guid=uuid`` 911 value for the GUID for the BMC, in standard UUID format. If this 912 is set, get "Get GUID" command to the BMC will return it. 913 Otherwise "Get GUID" will return an error. 914 915``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]`` 916 Add a connection to an external IPMI BMC simulator. Instead of 917 locally emulating the BMC like the above item, instead connect to an 918 external entity that provides the IPMI services. 919 920 A connection is made to an external BMC simulator. If you do this, 921 it is strongly recommended that you use the "reconnect=" chardev 922 option to reconnect to the simulator if the connection is lost. Note 923 that if this is not used carefully, it can be a security issue, as 924 the interface has the ability to send resets, NMIs, and power off 925 the VM. It's best if QEMU makes a connection to an external 926 simulator running on a secure port on localhost, so neither the 927 simulator nor QEMU is exposed to any outside network. 928 929 See the "lanserv/README.vm" file in the OpenIPMI library for more 930 details on the external interface. 931 932``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]`` 933 Add a KCS IPMI interafce on the ISA bus. This also adds a 934 corresponding ACPI and SMBIOS entries, if appropriate. 935 936 ``bmc=id`` 937 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern 938 above. 939 940 ``ioport=val`` 941 Define the I/O address of the interface. The default is 0xca0 942 for KCS. 943 944 ``irq=val`` 945 Define the interrupt to use. The default is 5. To disable 946 interrupts, set this to 0. 947 948``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]`` 949 Like the KCS interface, but defines a BT interface. The default port 950 is 0xe4 and the default interrupt is 5. 951 952``-device pci-ipmi-kcs,bmc=id`` 953 Add a KCS IPMI interafce on the PCI bus. 954 955 ``bmc=id`` 956 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above. 957 958``-device pci-ipmi-bt,bmc=id`` 959 Like the KCS interface, but defines a BT interface on the PCI bus. 960 961``-device intel-iommu[,option=...]`` 962 This is only supported by ``-machine q35``, which will enable Intel VT-d 963 emulation within the guest. It supports below options: 964 965 ``intremap=on|off`` (default: auto) 966 This enables interrupt remapping feature. It's required to enable 967 complete x2apic. Currently it only supports kvm kernel-irqchip modes 968 ``off`` or ``split``, while full kernel-irqchip is not yet supported. 969 The default value is "auto", which will be decided by the mode of 970 kernel-irqchip. 971 972 ``caching-mode=on|off`` (default: off) 973 This enables caching mode for the VT-d emulated device. When 974 caching-mode is enabled, each guest DMA buffer mapping will generate an 975 IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in 976 a synchronous way. It is required for ``-device vfio-pci`` to work 977 with the VT-d device, because host assigned devices requires to setup 978 the DMA mapping on the host before guest DMA starts. 979 980 ``device-iotlb=on|off`` (default: off) 981 This enables device-iotlb capability for the emulated VT-d device. So 982 far virtio/vhost should be the only real user for this parameter, 983 paired with ats=on configured for the device. 984 985 ``aw-bits=39|48`` (default: 39) 986 This decides the address width of IOVA address space. The address 987 space has 39 bits width for 3-level IOMMU page tables, and 48 bits for 988 4-level IOMMU page tables. 989 990 Please also refer to the wiki page for general scenarios of VT-d 991 emulation in QEMU: https://wiki.qemu.org/Features/VT-d. 992 993ERST 994 995DEF("name", HAS_ARG, QEMU_OPTION_name, 996 "-name string1[,process=string2][,debug-threads=on|off]\n" 997 " set the name of the guest\n" 998 " string1 sets the window title and string2 the process name\n" 999 " When debug-threads is enabled, individual threads are given a separate name\n" 1000 " NOTE: The thread names are for debugging and not a stable API.\n", 1001 QEMU_ARCH_ALL) 1002SRST 1003``-name name`` 1004 Sets the name of the guest. This name will be displayed in the SDL 1005 window caption. The name will also be used for the VNC server. Also 1006 optionally set the top visible process name in Linux. Naming of 1007 individual threads can also be enabled on Linux to aid debugging. 1008ERST 1009 1010DEF("uuid", HAS_ARG, QEMU_OPTION_uuid, 1011 "-uuid %08x-%04x-%04x-%04x-%012x\n" 1012 " specify machine UUID\n", QEMU_ARCH_ALL) 1013SRST 1014``-uuid uuid`` 1015 Set system UUID. 1016ERST 1017 1018DEFHEADING() 1019 1020DEFHEADING(Block device options:) 1021 1022DEF("fda", HAS_ARG, QEMU_OPTION_fda, 1023 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL) 1024DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL) 1025SRST 1026``-fda file`` 1027 \ 1028``-fdb file`` 1029 Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in 1030 the System Emulation Users Guide). 1031ERST 1032 1033DEF("hda", HAS_ARG, QEMU_OPTION_hda, 1034 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL) 1035DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL) 1036DEF("hdc", HAS_ARG, QEMU_OPTION_hdc, 1037 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL) 1038DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL) 1039SRST 1040``-hda file`` 1041 \ 1042``-hdb file`` 1043 \ 1044``-hdc file`` 1045 \ 1046``-hdd file`` 1047 Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images` 1048 chapter in the System Emulation Users Guide). 1049ERST 1050 1051DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom, 1052 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n", 1053 QEMU_ARCH_ALL) 1054SRST 1055``-cdrom file`` 1056 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at 1057 the same time). You can use the host CD-ROM by using ``/dev/cdrom`` 1058 as filename. 1059ERST 1060 1061DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev, 1062 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n" 1063 " [,cache.direct=on|off][,cache.no-flush=on|off]\n" 1064 " [,read-only=on|off][,auto-read-only=on|off]\n" 1065 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n" 1066 " [,driver specific parameters...]\n" 1067 " configure a block backend\n", QEMU_ARCH_ALL) 1068SRST 1069``-blockdev option[,option[,option[,...]]]`` 1070 Define a new block driver node. Some of the options apply to all 1071 block drivers, other options are only accepted for a specific block 1072 driver. See below for a list of generic options and options for the 1073 most common block drivers. 1074 1075 Options that expect a reference to another node (e.g. ``file``) can 1076 be given in two ways. Either you specify the node name of an already 1077 existing node (file=node-name), or you define a new node inline, 1078 adding options for the referenced node after a dot 1079 (file.filename=path,file.aio=native). 1080 1081 A block driver node created with ``-blockdev`` can be used for a 1082 guest device by specifying its node name for the ``drive`` property 1083 in a ``-device`` argument that defines a block device. 1084 1085 ``Valid options for any block driver node:`` 1086 ``driver`` 1087 Specifies the block driver to use for the given node. 1088 1089 ``node-name`` 1090 This defines the name of the block driver node by which it 1091 will be referenced later. The name must be unique, i.e. it 1092 must not match the name of a different block driver node, or 1093 (if you use ``-drive`` as well) the ID of a drive. 1094 1095 If no node name is specified, it is automatically generated. 1096 The generated node name is not intended to be predictable 1097 and changes between QEMU invocations. For the top level, an 1098 explicit node name must be specified. 1099 1100 ``read-only`` 1101 Open the node read-only. Guest write attempts will fail. 1102 1103 Note that some block drivers support only read-only access, 1104 either generally or in certain configurations. In this case, 1105 the default value ``read-only=off`` does not work and the 1106 option must be specified explicitly. 1107 1108 ``auto-read-only`` 1109 If ``auto-read-only=on`` is set, QEMU may fall back to 1110 read-only usage even when ``read-only=off`` is requested, or 1111 even switch between modes as needed, e.g. depending on 1112 whether the image file is writable or whether a writing user 1113 is attached to the node. 1114 1115 ``force-share`` 1116 Override the image locking system of QEMU by forcing the 1117 node to utilize weaker shared access for permissions where 1118 it would normally request exclusive access. When there is 1119 the potential for multiple instances to have the same file 1120 open (whether this invocation of QEMU is the first or the 1121 second instance), both instances must permit shared access 1122 for the second instance to succeed at opening the file. 1123 1124 Enabling ``force-share=on`` requires ``read-only=on``. 1125 1126 ``cache.direct`` 1127 The host page cache can be avoided with ``cache.direct=on``. 1128 This will attempt to do disk IO directly to the guest's 1129 memory. QEMU may still perform an internal copy of the data. 1130 1131 ``cache.no-flush`` 1132 In case you don't care about data integrity over host 1133 failures, you can use ``cache.no-flush=on``. This option 1134 tells QEMU that it never needs to write any data to the disk 1135 but can instead keep things in cache. If anything goes 1136 wrong, like your host losing power, the disk storage getting 1137 disconnected accidentally, etc. your image will most 1138 probably be rendered unusable. 1139 1140 ``discard=discard`` 1141 discard is one of "ignore" (or "off") or "unmap" (or "on") 1142 and controls whether ``discard`` (also known as ``trim`` or 1143 ``unmap``) requests are ignored or passed to the filesystem. 1144 Some machine types may not support discard requests. 1145 1146 ``detect-zeroes=detect-zeroes`` 1147 detect-zeroes is "off", "on" or "unmap" and enables the 1148 automatic conversion of plain zero writes by the OS to 1149 driver specific optimized zero write commands. You may even 1150 choose "unmap" if discard is set to "unmap" to allow a zero 1151 write to be converted to an ``unmap`` operation. 1152 1153 ``Driver-specific options for file`` 1154 This is the protocol-level block driver for accessing regular 1155 files. 1156 1157 ``filename`` 1158 The path to the image file in the local filesystem 1159 1160 ``aio`` 1161 Specifies the AIO backend (threads/native/io_uring, 1162 default: threads) 1163 1164 ``locking`` 1165 Specifies whether the image file is protected with Linux OFD 1166 / POSIX locks. The default is to use the Linux Open File 1167 Descriptor API if available, otherwise no lock is applied. 1168 (auto/on/off, default: auto) 1169 1170 Example: 1171 1172 :: 1173 1174 -blockdev driver=file,node-name=disk,filename=disk.img 1175 1176 ``Driver-specific options for raw`` 1177 This is the image format block driver for raw images. It is 1178 usually stacked on top of a protocol level block driver such as 1179 ``file``. 1180 1181 ``file`` 1182 Reference to or definition of the data source block driver 1183 node (e.g. a ``file`` driver node) 1184 1185 Example 1: 1186 1187 :: 1188 1189 -blockdev driver=file,node-name=disk_file,filename=disk.img 1190 -blockdev driver=raw,node-name=disk,file=disk_file 1191 1192 Example 2: 1193 1194 :: 1195 1196 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img 1197 1198 ``Driver-specific options for qcow2`` 1199 This is the image format block driver for qcow2 images. It is 1200 usually stacked on top of a protocol level block driver such as 1201 ``file``. 1202 1203 ``file`` 1204 Reference to or definition of the data source block driver 1205 node (e.g. a ``file`` driver node) 1206 1207 ``backing`` 1208 Reference to or definition of the backing file block device 1209 (default is taken from the image file). It is allowed to 1210 pass ``null`` here in order to disable the default backing 1211 file. 1212 1213 ``lazy-refcounts`` 1214 Whether to enable the lazy refcounts feature (on/off; 1215 default is taken from the image file) 1216 1217 ``cache-size`` 1218 The maximum total size of the L2 table and refcount block 1219 caches in bytes (default: the sum of l2-cache-size and 1220 refcount-cache-size) 1221 1222 ``l2-cache-size`` 1223 The maximum size of the L2 table cache in bytes (default: if 1224 cache-size is not specified - 32M on Linux platforms, and 8M 1225 on non-Linux platforms; otherwise, as large as possible 1226 within the cache-size, while permitting the requested or the 1227 minimal refcount cache size) 1228 1229 ``refcount-cache-size`` 1230 The maximum size of the refcount block cache in bytes 1231 (default: 4 times the cluster size; or if cache-size is 1232 specified, the part of it which is not used for the L2 1233 cache) 1234 1235 ``cache-clean-interval`` 1236 Clean unused entries in the L2 and refcount caches. The 1237 interval is in seconds. The default value is 600 on 1238 supporting platforms, and 0 on other platforms. Setting it 1239 to 0 disables this feature. 1240 1241 ``pass-discard-request`` 1242 Whether discard requests to the qcow2 device should be 1243 forwarded to the data source (on/off; default: on if 1244 discard=unmap is specified, off otherwise) 1245 1246 ``pass-discard-snapshot`` 1247 Whether discard requests for the data source should be 1248 issued when a snapshot operation (e.g. deleting a snapshot) 1249 frees clusters in the qcow2 file (on/off; default: on) 1250 1251 ``pass-discard-other`` 1252 Whether discard requests for the data source should be 1253 issued on other occasions where a cluster gets freed 1254 (on/off; default: off) 1255 1256 ``overlap-check`` 1257 Which overlap checks to perform for writes to the image 1258 (none/constant/cached/all; default: cached). For details or 1259 finer granularity control refer to the QAPI documentation of 1260 ``blockdev-add``. 1261 1262 Example 1: 1263 1264 :: 1265 1266 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2 1267 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216 1268 1269 Example 2: 1270 1271 :: 1272 1273 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2 1274 1275 ``Driver-specific options for other drivers`` 1276 Please refer to the QAPI documentation of the ``blockdev-add`` 1277 QMP command. 1278ERST 1279 1280DEF("drive", HAS_ARG, QEMU_OPTION_drive, 1281 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" 1282 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" 1283 " [,snapshot=on|off][,rerror=ignore|stop|report]\n" 1284 " [,werror=ignore|stop|report|enospc][,id=name]\n" 1285 " [,aio=threads|native|io_uring]\n" 1286 " [,readonly=on|off][,copy-on-read=on|off]\n" 1287 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n" 1288 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n" 1289 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n" 1290 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n" 1291 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n" 1292 " [[,iops_size=is]]\n" 1293 " [[,group=g]]\n" 1294 " use 'file' as a drive image\n", QEMU_ARCH_ALL) 1295SRST 1296``-drive option[,option[,option[,...]]]`` 1297 Define a new drive. This includes creating a block driver node (the 1298 backend) as well as a guest device, and is mostly a shortcut for 1299 defining the corresponding ``-blockdev`` and ``-device`` options. 1300 1301 ``-drive`` accepts all options that are accepted by ``-blockdev``. 1302 In addition, it knows the following options: 1303 1304 ``file=file`` 1305 This option defines which disk image (see the :ref:`disk images` 1306 chapter in the System Emulation Users Guide) to use with this drive. 1307 If the filename contains comma, you must double it (for instance, 1308 "file=my,,file" to use file "my,file"). 1309 1310 Special files such as iSCSI devices can be specified using 1311 protocol specific URLs. See the section for "Device URL Syntax" 1312 for more information. 1313 1314 ``if=interface`` 1315 This option defines on which type on interface the drive is 1316 connected. Available types are: ide, scsi, sd, mtd, floppy, 1317 pflash, virtio, none. 1318 1319 ``bus=bus,unit=unit`` 1320 These options define where is connected the drive by defining 1321 the bus number and the unit id. 1322 1323 ``index=index`` 1324 This option defines where is connected the drive by using an 1325 index in the list of available connectors of a given interface 1326 type. 1327 1328 ``media=media`` 1329 This option defines the type of the media: disk or cdrom. 1330 1331 ``snapshot=snapshot`` 1332 snapshot is "on" or "off" and controls snapshot mode for the 1333 given drive (see ``-snapshot``). 1334 1335 ``cache=cache`` 1336 cache is "none", "writeback", "unsafe", "directsync" or 1337 "writethrough" and controls how the host cache is used to access 1338 block data. This is a shortcut that sets the ``cache.direct`` 1339 and ``cache.no-flush`` options (as in ``-blockdev``), and 1340 additionally ``cache.writeback``, which provides a default for 1341 the ``write-cache`` option of block guest devices (as in 1342 ``-device``). The modes correspond to the following settings: 1343 1344 ============= =============== ============ ============== 1345 \ cache.writeback cache.direct cache.no-flush 1346 ============= =============== ============ ============== 1347 writeback on off off 1348 none on on off 1349 writethrough off off off 1350 directsync off on off 1351 unsafe on off on 1352 ============= =============== ============ ============== 1353 1354 The default mode is ``cache=writeback``. 1355 1356 ``aio=aio`` 1357 aio is "threads", "native", or "io_uring" and selects between pthread 1358 based disk I/O, native Linux AIO, or Linux io_uring API. 1359 1360 ``format=format`` 1361 Specify which disk format will be used rather than detecting the 1362 format. Can be used to specify format=raw to avoid interpreting 1363 an untrusted format header. 1364 1365 ``werror=action,rerror=action`` 1366 Specify which action to take on write and read errors. Valid 1367 actions are: "ignore" (ignore the error and try to continue), 1368 "stop" (pause QEMU), "report" (report the error to the guest), 1369 "enospc" (pause QEMU only if the host disk is full; report the 1370 error to the guest otherwise). The default setting is 1371 ``werror=enospc`` and ``rerror=report``. 1372 1373 ``copy-on-read=copy-on-read`` 1374 copy-on-read is "on" or "off" and enables whether to copy read 1375 backing file sectors into the image file. 1376 1377 ``bps=b,bps_rd=r,bps_wr=w`` 1378 Specify bandwidth throttling limits in bytes per second, either 1379 for all request types or for reads or writes only. Small values 1380 can lead to timeouts or hangs inside the guest. A safe minimum 1381 for disks is 2 MB/s. 1382 1383 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm`` 1384 Specify bursts in bytes per second, either for all request types 1385 or for reads or writes only. Bursts allow the guest I/O to spike 1386 above the limit temporarily. 1387 1388 ``iops=i,iops_rd=r,iops_wr=w`` 1389 Specify request rate limits in requests per second, either for 1390 all request types or for reads or writes only. 1391 1392 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm`` 1393 Specify bursts in requests per second, either for all request 1394 types or for reads or writes only. Bursts allow the guest I/O to 1395 spike above the limit temporarily. 1396 1397 ``iops_size=is`` 1398 Let every is bytes of a request count as a new request for iops 1399 throttling purposes. Use this option to prevent guests from 1400 circumventing iops limits by sending fewer but larger requests. 1401 1402 ``group=g`` 1403 Join a throttling quota group with given name g. All drives that 1404 are members of the same group are accounted for together. Use 1405 this option to prevent guests from circumventing throttling 1406 limits by using many small disks instead of a single larger 1407 disk. 1408 1409 By default, the ``cache.writeback=on`` mode is used. It will report 1410 data writes as completed as soon as the data is present in the host 1411 page cache. This is safe as long as your guest OS makes sure to 1412 correctly flush disk caches where needed. If your guest OS does not 1413 handle volatile disk write caches correctly and your host crashes or 1414 loses power, then the guest may experience data corruption. 1415 1416 For such guests, you should consider using ``cache.writeback=off``. 1417 This means that the host page cache will be used to read and write 1418 data, but write notification will be sent to the guest only after 1419 QEMU has made sure to flush each write to the disk. Be aware that 1420 this has a major impact on performance. 1421 1422 When using the ``-snapshot`` option, unsafe caching is always used. 1423 1424 Copy-on-read avoids accessing the same backing file sectors 1425 repeatedly and is useful when the backing file is over a slow 1426 network. By default copy-on-read is off. 1427 1428 Instead of ``-cdrom`` you can use: 1429 1430 .. parsed-literal:: 1431 1432 |qemu_system| -drive file=file,index=2,media=cdrom 1433 1434 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use: 1435 1436 .. parsed-literal:: 1437 1438 |qemu_system| -drive file=file,index=0,media=disk 1439 |qemu_system| -drive file=file,index=1,media=disk 1440 |qemu_system| -drive file=file,index=2,media=disk 1441 |qemu_system| -drive file=file,index=3,media=disk 1442 1443 You can open an image using pre-opened file descriptors from an fd 1444 set: 1445 1446 .. parsed-literal:: 1447 1448 |qemu_system| \\ 1449 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 1450 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 1451 -drive file=/dev/fdset/2,index=0,media=disk 1452 1453 You can connect a CDROM to the slave of ide0: 1454 1455 .. parsed-literal:: 1456 1457 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom 1458 1459 If you don't specify the "file=" argument, you define an empty 1460 drive: 1461 1462 .. parsed-literal:: 1463 1464 |qemu_system_x86| -drive if=ide,index=1,media=cdrom 1465 1466 Instead of ``-fda``, ``-fdb``, you can use: 1467 1468 .. parsed-literal:: 1469 1470 |qemu_system_x86| -drive file=file,index=0,if=floppy 1471 |qemu_system_x86| -drive file=file,index=1,if=floppy 1472 1473 By default, interface is "ide" and index is automatically 1474 incremented: 1475 1476 .. parsed-literal:: 1477 1478 |qemu_system_x86| -drive file=a -drive file=b" 1479 1480 is interpreted like: 1481 1482 .. parsed-literal:: 1483 1484 |qemu_system_x86| -hda a -hdb b 1485ERST 1486 1487DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock, 1488 "-mtdblock file use 'file' as on-board Flash memory image\n", 1489 QEMU_ARCH_ALL) 1490SRST 1491``-mtdblock file`` 1492 Use file as on-board Flash memory image. 1493ERST 1494 1495DEF("sd", HAS_ARG, QEMU_OPTION_sd, 1496 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL) 1497SRST 1498``-sd file`` 1499 Use file as SecureDigital card image. 1500ERST 1501 1502DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, 1503 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) 1504SRST 1505``-pflash file`` 1506 Use file as a parallel flash image. 1507ERST 1508 1509DEF("snapshot", 0, QEMU_OPTION_snapshot, 1510 "-snapshot write to temporary files instead of disk image files\n", 1511 QEMU_ARCH_ALL) 1512SRST 1513``-snapshot`` 1514 Write to temporary files instead of disk image files. In this case, 1515 the raw disk image you use is not written back. You can however 1516 force the write back by pressing C-a s (see the :ref:`disk images` 1517 chapter in the System Emulation Users Guide). 1518ERST 1519 1520DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev, 1521 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1522 " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n" 1523 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n" 1524 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n" 1525 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n" 1526 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n" 1527 " [[,throttling.iops-size=is]]\n" 1528 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n" 1529 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n" 1530 "-fsdev synth,id=id\n", 1531 QEMU_ARCH_ALL) 1532 1533SRST 1534``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]`` 1535 \ 1536``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]`` 1537 \ 1538``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]`` 1539 \ 1540``-fsdev synth,id=id[,readonly=on]`` 1541 Define a new file system device. Valid options are: 1542 1543 ``local`` 1544 Accesses to the filesystem are done by QEMU. 1545 1546 ``proxy`` 1547 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1548 1549 ``synth`` 1550 Synthetic filesystem, only used by QTests. 1551 1552 ``id=id`` 1553 Specifies identifier for this device. 1554 1555 ``path=path`` 1556 Specifies the export path for the file system device. Files 1557 under this path will be available to the 9p client on the guest. 1558 1559 ``security_model=security_model`` 1560 Specifies the security model to be used for this export path. 1561 Supported security models are "passthrough", "mapped-xattr", 1562 "mapped-file" and "none". In "passthrough" security model, files 1563 are stored using the same credentials as they are created on the 1564 guest. This requires QEMU to run as root. In "mapped-xattr" 1565 security model, some of the file attributes like uid, gid, mode 1566 bits and link target are stored as file attributes. For 1567 "mapped-file" these attributes are stored in the hidden 1568 .virtfs\_metadata directory. Directories exported by this 1569 security model cannot interact with other unix tools. "none" 1570 security model is same as passthrough except the sever won't 1571 report failures if it fails to set file attributes like 1572 ownership. Security model is mandatory only for local fsdriver. 1573 Other fsdrivers (like proxy) don't take security model as a 1574 parameter. 1575 1576 ``writeout=writeout`` 1577 This is an optional argument. The only supported value is 1578 "immediate". This means that host page cache will be used to 1579 read and write data but write notification will be sent to the 1580 guest only when the data has been reported as written by the 1581 storage subsystem. 1582 1583 ``readonly=on`` 1584 Enables exporting 9p share as a readonly mount for guests. By 1585 default read-write access is given. 1586 1587 ``socket=socket`` 1588 Enables proxy filesystem driver to use passed socket file for 1589 communicating with virtfs-proxy-helper(1). 1590 1591 ``sock_fd=sock_fd`` 1592 Enables proxy filesystem driver to use passed socket descriptor 1593 for communicating with virtfs-proxy-helper(1). Usually a helper 1594 like libvirt will create socketpair and pass one of the fds as 1595 sock\_fd. 1596 1597 ``fmode=fmode`` 1598 Specifies the default mode for newly created files on the host. 1599 Works only with security models "mapped-xattr" and 1600 "mapped-file". 1601 1602 ``dmode=dmode`` 1603 Specifies the default mode for newly created directories on the 1604 host. Works only with security models "mapped-xattr" and 1605 "mapped-file". 1606 1607 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w`` 1608 Specify bandwidth throttling limits in bytes per second, either 1609 for all request types or for reads or writes only. 1610 1611 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm`` 1612 Specify bursts in bytes per second, either for all request types 1613 or for reads or writes only. Bursts allow the guest I/O to spike 1614 above the limit temporarily. 1615 1616 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w`` 1617 Specify request rate limits in requests per second, either for 1618 all request types or for reads or writes only. 1619 1620 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm`` 1621 Specify bursts in requests per second, either for all request 1622 types or for reads or writes only. Bursts allow the guest I/O to 1623 spike above the limit temporarily. 1624 1625 ``throttling.iops-size=is`` 1626 Let every is bytes of a request count as a new request for iops 1627 throttling purposes. 1628 1629 -fsdev option is used along with -device driver "virtio-9p-...". 1630 1631``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag`` 1632 Options for virtio-9p-... driver are: 1633 1634 ``type`` 1635 Specifies the variant to be used. Supported values are "pci", 1636 "ccw" or "device", depending on the machine type. 1637 1638 ``fsdev=id`` 1639 Specifies the id value specified along with -fsdev option. 1640 1641 ``mount_tag=mount_tag`` 1642 Specifies the tag name to be used by the guest to mount this 1643 export point. 1644ERST 1645 1646DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, 1647 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1648 " [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n" 1649 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n" 1650 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n" 1651 "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n", 1652 QEMU_ARCH_ALL) 1653 1654SRST 1655``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]`` 1656 \ 1657``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1658 \ 1659``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1660 \ 1661``-virtfs synth,mount_tag=mount_tag`` 1662 Define a new virtual filesystem device and expose it to the guest using 1663 a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain 1664 directory on host is made directly accessible by guest as a pass-through 1665 file system by using the 9P network protocol for communication between 1666 host and guests, if desired even accessible, shared by several guests 1667 simultaniously. 1668 1669 Note that ``-virtfs`` is actually just a convenience shortcut for its 1670 generalized form ``-fsdev -device virtio-9p-pci``. 1671 1672 The general form of pass-through file system options are: 1673 1674 ``local`` 1675 Accesses to the filesystem are done by QEMU. 1676 1677 ``proxy`` 1678 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1679 1680 ``synth`` 1681 Synthetic filesystem, only used by QTests. 1682 1683 ``id=id`` 1684 Specifies identifier for the filesystem device 1685 1686 ``path=path`` 1687 Specifies the export path for the file system device. Files 1688 under this path will be available to the 9p client on the guest. 1689 1690 ``security_model=security_model`` 1691 Specifies the security model to be used for this export path. 1692 Supported security models are "passthrough", "mapped-xattr", 1693 "mapped-file" and "none". In "passthrough" security model, files 1694 are stored using the same credentials as they are created on the 1695 guest. This requires QEMU to run as root. In "mapped-xattr" 1696 security model, some of the file attributes like uid, gid, mode 1697 bits and link target are stored as file attributes. For 1698 "mapped-file" these attributes are stored in the hidden 1699 .virtfs\_metadata directory. Directories exported by this 1700 security model cannot interact with other unix tools. "none" 1701 security model is same as passthrough except the sever won't 1702 report failures if it fails to set file attributes like 1703 ownership. Security model is mandatory only for local fsdriver. 1704 Other fsdrivers (like proxy) don't take security model as a 1705 parameter. 1706 1707 ``writeout=writeout`` 1708 This is an optional argument. The only supported value is 1709 "immediate". This means that host page cache will be used to 1710 read and write data but write notification will be sent to the 1711 guest only when the data has been reported as written by the 1712 storage subsystem. 1713 1714 ``readonly=on`` 1715 Enables exporting 9p share as a readonly mount for guests. By 1716 default read-write access is given. 1717 1718 ``socket=socket`` 1719 Enables proxy filesystem driver to use passed socket file for 1720 communicating with virtfs-proxy-helper(1). Usually a helper like 1721 libvirt will create socketpair and pass one of the fds as 1722 sock\_fd. 1723 1724 ``sock_fd`` 1725 Enables proxy filesystem driver to use passed 'sock\_fd' as the 1726 socket descriptor for interfacing with virtfs-proxy-helper(1). 1727 1728 ``fmode=fmode`` 1729 Specifies the default mode for newly created files on the host. 1730 Works only with security models "mapped-xattr" and 1731 "mapped-file". 1732 1733 ``dmode=dmode`` 1734 Specifies the default mode for newly created directories on the 1735 host. Works only with security models "mapped-xattr" and 1736 "mapped-file". 1737 1738 ``mount_tag=mount_tag`` 1739 Specifies the tag name to be used by the guest to mount this 1740 export point. 1741 1742 ``multidevs=multidevs`` 1743 Specifies how to deal with multiple devices being shared with a 1744 9p export. Supported behaviours are either "remap", "forbid" or 1745 "warn". The latter is the default behaviour on which virtfs 9p 1746 expects only one device to be shared with the same export, and 1747 if more than one device is shared and accessed via the same 9p 1748 export then only a warning message is logged (once) by qemu on 1749 host side. In order to avoid file ID collisions on guest you 1750 should either create a separate virtfs export for each device to 1751 be shared with guests (recommended way) or you might use "remap" 1752 instead which allows you to share multiple devices with only one 1753 export instead, which is achieved by remapping the original 1754 inode numbers from host to guest in a way that would prevent 1755 such collisions. Remapping inodes in such use cases is required 1756 because the original device IDs from host are never passed and 1757 exposed on guest. Instead all files of an export shared with 1758 virtfs always share the same device id on guest. So two files 1759 with identical inode numbers but from actually different devices 1760 on host would otherwise cause a file ID collision and hence 1761 potential misbehaviours on guest. "forbid" on the other hand 1762 assumes like "warn" that only one device is shared by the same 1763 export, however it will not only log a warning message but also 1764 deny access to additional devices on guest. Note though that 1765 "forbid" does currently not block all possible file access 1766 operations (e.g. readdir() would still return entries from other 1767 devices). 1768ERST 1769 1770DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi, 1771 "-iscsi [user=user][,password=password]\n" 1772 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n" 1773 " [,initiator-name=initiator-iqn][,id=target-iqn]\n" 1774 " [,timeout=timeout]\n" 1775 " iSCSI session parameters\n", QEMU_ARCH_ALL) 1776 1777SRST 1778``-iscsi`` 1779 Configure iSCSI session parameters. 1780ERST 1781 1782DEFHEADING() 1783 1784DEFHEADING(USB convenience options:) 1785 1786DEF("usb", 0, QEMU_OPTION_usb, 1787 "-usb enable on-board USB host controller (if not enabled by default)\n", 1788 QEMU_ARCH_ALL) 1789SRST 1790``-usb`` 1791 Enable USB emulation on machine types with an on-board USB host 1792 controller (if not enabled by default). Note that on-board USB host 1793 controllers may not support USB 3.0. In this case 1794 ``-device qemu-xhci`` can be used instead on machines with PCI. 1795ERST 1796 1797DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice, 1798 "-usbdevice name add the host or guest USB device 'name'\n", 1799 QEMU_ARCH_ALL) 1800SRST 1801``-usbdevice devname`` 1802 Add the USB device devname, and enable an on-board USB controller 1803 if possible and necessary (just like it can be done via 1804 ``-machine usb=on``). Note that this option is mainly intended for 1805 the user's convenience only. More fine-grained control can be 1806 achieved by selecting a USB host controller (if necessary) and the 1807 desired USB device via the ``-device`` option instead. For example, 1808 instead of using ``-usbdevice mouse`` it is possible to use 1809 ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse 1810 to a USB 3.0 controller instead (at least on machines that support 1811 PCI and do not have an USB controller enabled by default yet). 1812 For more details, see the chapter about 1813 :ref:`Connecting USB devices` in the System Emulation Users Guide. 1814 Possible devices for devname are: 1815 1816 ``braille`` 1817 Braille device. This will use BrlAPI to display the braille 1818 output on a real or fake device (i.e. it also creates a 1819 corresponding ``braille`` chardev automatically beside the 1820 ``usb-braille`` USB device). 1821 1822 ``keyboard`` 1823 Standard USB keyboard. Will override the PS/2 keyboard (if present). 1824 1825 ``mouse`` 1826 Virtual Mouse. This will override the PS/2 mouse emulation when 1827 activated. 1828 1829 ``tablet`` 1830 Pointer device that uses absolute coordinates (like a 1831 touchscreen). This means QEMU is able to report the mouse 1832 position without having to grab the mouse. Also overrides the 1833 PS/2 mouse emulation when activated. 1834 1835 ``wacom-tablet`` 1836 Wacom PenPartner USB tablet. 1837 1838 1839ERST 1840 1841DEFHEADING() 1842 1843DEFHEADING(Display options:) 1844 1845DEF("display", HAS_ARG, QEMU_OPTION_display, 1846#if defined(CONFIG_SPICE) 1847 "-display spice-app[,gl=on|off]\n" 1848#endif 1849#if defined(CONFIG_SDL) 1850 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off][,gl=on|core|es|off]\n" 1851 " [,grab-mod=<mod>][,show-cursor=on|off][,window-close=on|off]\n" 1852#endif 1853#if defined(CONFIG_GTK) 1854 "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n" 1855 " [,show-cursor=on|off][,window-close=on|off]\n" 1856#endif 1857#if defined(CONFIG_VNC) 1858 "-display vnc=<display>[,<optargs>]\n" 1859#endif 1860#if defined(CONFIG_CURSES) 1861 "-display curses[,charset=<encoding>]\n" 1862#endif 1863#if defined(CONFIG_OPENGL) 1864 "-display egl-headless[,rendernode=<file>]\n" 1865#endif 1866 "-display none\n" 1867 " select display backend type\n" 1868 " The default display is equivalent to\n " 1869#if defined(CONFIG_GTK) 1870 "\"-display gtk\"\n" 1871#elif defined(CONFIG_SDL) 1872 "\"-display sdl\"\n" 1873#elif defined(CONFIG_COCOA) 1874 "\"-display cocoa\"\n" 1875#elif defined(CONFIG_VNC) 1876 "\"-vnc localhost:0,to=99,id=default\"\n" 1877#else 1878 "\"-display none\"\n" 1879#endif 1880 , QEMU_ARCH_ALL) 1881SRST 1882``-display type`` 1883 Select type of display to use. This option is a replacement for the 1884 old style -sdl/-curses/... options. Use ``-display help`` to list 1885 the available display types. Valid values for type are 1886 1887 ``spice-app[,gl=on|off]`` 1888 Start QEMU as a Spice server and launch the default Spice client 1889 application. The Spice server will redirect the serial consoles 1890 and QEMU monitors. (Since 4.0) 1891 1892 ``sdl`` 1893 Display video output via SDL (usually in a separate graphics 1894 window; see the SDL documentation for other possibilities). 1895 Valid parameters are: 1896 1897 ``grab-mod=<mods>`` : Used to select the modifier keys for toggling 1898 the mouse grabbing in conjunction with the "g" key. `<mods>` can be 1899 either `lshift-lctrl-lalt` or `rctrl`. 1900 1901 ``alt_grab=on|off`` : Use Control+Alt+Shift-g to toggle mouse grabbing. 1902 This parameter is deprecated - use ``grab-mod`` instead. 1903 1904 ``ctrl_grab=on|off`` : Use Right-Control-g to toggle mouse grabbing. 1905 This parameter is deprecated - use ``grab-mod`` instead. 1906 1907 ``gl=on|off|core|es`` : Use OpenGL for displaying 1908 1909 ``show-cursor=on|off`` : Force showing the mouse cursor 1910 1911 ``window-close=on|off`` : Allow to quit qemu with window close button 1912 1913 ``gtk`` 1914 Display video output in a GTK window. This interface provides 1915 drop-down menus and other UI elements to configure and control 1916 the VM during runtime. Valid parameters are: 1917 1918 ``full-screen=on|off`` : Start in fullscreen mode 1919 1920 ``gl=on|off`` : Use OpenGL for displaying 1921 1922 ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover 1923 1924 ``show-cursor=on|off`` : Force showing the mouse cursor 1925 1926 ``window-close=on|off`` : Allow to quit qemu with window close button 1927 1928 ``curses[,charset=<encoding>]`` 1929 Display video output via curses. For graphics device models 1930 which support a text mode, QEMU can display this output using a 1931 curses/ncurses interface. Nothing is displayed when the graphics 1932 device is in graphical mode or if the graphics device does not 1933 support a text mode. Generally only the VGA device models 1934 support text mode. The font charset used by the guest can be 1935 specified with the ``charset`` option, for example 1936 ``charset=CP850`` for IBM CP850 encoding. The default is 1937 ``CP437``. 1938 1939 ``egl-headless[,rendernode=<file>]`` 1940 Offload all OpenGL operations to a local DRI device. For any 1941 graphical display, this display needs to be paired with either 1942 VNC or SPICE displays. 1943 1944 ``vnc=<display>`` 1945 Start a VNC server on display <display> 1946 1947 ``none`` 1948 Do not display video output. The guest will still see an 1949 emulated graphics card, but its output will not be displayed to 1950 the QEMU user. This option differs from the -nographic option in 1951 that it only affects what is done with video output; -nographic 1952 also changes the destination of the serial and parallel port 1953 data. 1954ERST 1955 1956DEF("nographic", 0, QEMU_OPTION_nographic, 1957 "-nographic disable graphical output and redirect serial I/Os to console\n", 1958 QEMU_ARCH_ALL) 1959SRST 1960``-nographic`` 1961 Normally, if QEMU is compiled with graphical window support, it 1962 displays output such as guest graphics, guest console, and the QEMU 1963 monitor in a window. With this option, you can totally disable 1964 graphical output so that QEMU is a simple command line application. 1965 The emulated serial port is redirected on the console and muxed with 1966 the monitor (unless redirected elsewhere explicitly). Therefore, you 1967 can still use QEMU to debug a Linux kernel with a serial console. 1968 Use C-a h for help on switching between the console and monitor. 1969ERST 1970 1971DEF("curses", 0, QEMU_OPTION_curses, 1972 "-curses shorthand for -display curses\n", 1973 QEMU_ARCH_ALL) 1974SRST 1975``-curses`` 1976 Normally, if QEMU is compiled with graphical window support, it 1977 displays output such as guest graphics, guest console, and the QEMU 1978 monitor in a window. With this option, QEMU can display the VGA 1979 output when in text mode using a curses/ncurses interface. Nothing 1980 is displayed in graphical mode. 1981ERST 1982 1983DEF("alt-grab", 0, QEMU_OPTION_alt_grab, 1984 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n", 1985 QEMU_ARCH_ALL) 1986SRST 1987``-alt-grab`` 1988 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that 1989 this also affects the special keys (for fullscreen, monitor-mode 1990 switching, etc). This option is deprecated - please use 1991 ``-display sdl,grab-mod=lshift-lctrl-lalt`` instead. 1992ERST 1993 1994DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab, 1995 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n", 1996 QEMU_ARCH_ALL) 1997SRST 1998``-ctrl-grab`` 1999 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this 2000 also affects the special keys (for fullscreen, monitor-mode 2001 switching, etc). This option is deprecated - please use 2002 ``-display sdl,grab-mod=rctrl`` instead. 2003ERST 2004 2005DEF("no-quit", 0, QEMU_OPTION_no_quit, 2006 "-no-quit disable SDL/GTK window close capability (deprecated)\n", QEMU_ARCH_ALL) 2007SRST 2008``-no-quit`` 2009 Disable window close capability (SDL and GTK only). This option is 2010 deprecated, please use ``-display ...,window-close=off`` instead. 2011ERST 2012 2013DEF("sdl", 0, QEMU_OPTION_sdl, 2014 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL) 2015SRST 2016``-sdl`` 2017 Enable SDL. 2018ERST 2019 2020DEF("spice", HAS_ARG, QEMU_OPTION_spice, 2021 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n" 2022 " [,x509-key-file=<file>][,x509-key-password=<file>]\n" 2023 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n" 2024 " [,x509-dh-key-file=<file>][,addr=addr]\n" 2025 " [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n" 2026 " [,tls-ciphers=<list>]\n" 2027 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n" 2028 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n" 2029 " [,sasl=on|off][,disable-ticketing=on|off]\n" 2030 " [,password=<string>][,password-secret=<secret-id>]\n" 2031 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n" 2032 " [,jpeg-wan-compression=[auto|never|always]]\n" 2033 " [,zlib-glz-wan-compression=[auto|never|always]]\n" 2034 " [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n" 2035 " [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n" 2036 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n" 2037 " [,gl=[on|off]][,rendernode=<file>]\n" 2038 " enable spice\n" 2039 " at least one of {port, tls-port} is mandatory\n", 2040 QEMU_ARCH_ALL) 2041SRST 2042``-spice option[,option[,...]]`` 2043 Enable the spice remote desktop protocol. Valid options are 2044 2045 ``port=<nr>`` 2046 Set the TCP port spice is listening on for plaintext channels. 2047 2048 ``addr=<addr>`` 2049 Set the IP address spice is listening on. Default is any 2050 address. 2051 2052 ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off`` 2053 Force using the specified IP version. 2054 2055 ``password=<string>`` 2056 Set the password you need to authenticate. 2057 2058 This option is deprecated and insecure because it leaves the 2059 password visible in the process listing. Use ``password-secret`` 2060 instead. 2061 2062 ``password-secret=<secret-id>`` 2063 Set the ID of the ``secret`` object containing the password 2064 you need to authenticate. 2065 2066 ``sasl=on|off`` 2067 Require that the client use SASL to authenticate with the spice. 2068 The exact choice of authentication method used is controlled 2069 from the system / user's SASL configuration file for the 'qemu' 2070 service. This is typically found in /etc/sasl2/qemu.conf. If 2071 running QEMU as an unprivileged user, an environment variable 2072 SASL\_CONF\_PATH can be used to make it search alternate 2073 locations for the service config. While some SASL auth methods 2074 can also provide data encryption (eg GSSAPI), it is recommended 2075 that SASL always be combined with the 'tls' and 'x509' settings 2076 to enable use of SSL and server certificates. This ensures a 2077 data encryption preventing compromise of authentication 2078 credentials. 2079 2080 ``disable-ticketing=on|off`` 2081 Allow client connects without authentication. 2082 2083 ``disable-copy-paste=on|off`` 2084 Disable copy paste between the client and the guest. 2085 2086 ``disable-agent-file-xfer=on|off`` 2087 Disable spice-vdagent based file-xfer between the client and the 2088 guest. 2089 2090 ``tls-port=<nr>`` 2091 Set the TCP port spice is listening on for encrypted channels. 2092 2093 ``x509-dir=<dir>`` 2094 Set the x509 file directory. Expects same filenames as -vnc 2095 $display,x509=$dir 2096 2097 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>`` 2098 The x509 file names can also be configured individually. 2099 2100 ``tls-ciphers=<list>`` 2101 Specify which ciphers to use. 2102 2103 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]`` 2104 Force specific channel to be used with or without TLS 2105 encryption. The options can be specified multiple times to 2106 configure multiple channels. The special name "default" can be 2107 used to set the default mode. For channels which are not 2108 explicitly forced into one mode the spice client is allowed to 2109 pick tls/plaintext as he pleases. 2110 2111 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]`` 2112 Configure image compression (lossless). Default is auto\_glz. 2113 2114 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]`` 2115 Configure wan image compression (lossy for slow links). Default 2116 is auto. 2117 2118 ``streaming-video=[off|all|filter]`` 2119 Configure video stream detection. Default is off. 2120 2121 ``agent-mouse=[on|off]`` 2122 Enable/disable passing mouse events via vdagent. Default is on. 2123 2124 ``playback-compression=[on|off]`` 2125 Enable/disable audio stream compression (using celt 0.5.1). 2126 Default is on. 2127 2128 ``seamless-migration=[on|off]`` 2129 Enable/disable spice seamless migration. Default is off. 2130 2131 ``gl=[on|off]`` 2132 Enable/disable OpenGL context. Default is off. 2133 2134 ``rendernode=<file>`` 2135 DRM render node for OpenGL rendering. If not specified, it will 2136 pick the first available. (Since 2.9) 2137ERST 2138 2139DEF("portrait", 0, QEMU_OPTION_portrait, 2140 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n", 2141 QEMU_ARCH_ALL) 2142SRST 2143``-portrait`` 2144 Rotate graphical output 90 deg left (only PXA LCD). 2145ERST 2146 2147DEF("rotate", HAS_ARG, QEMU_OPTION_rotate, 2148 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n", 2149 QEMU_ARCH_ALL) 2150SRST 2151``-rotate deg`` 2152 Rotate graphical output some deg left (only PXA LCD). 2153ERST 2154 2155DEF("vga", HAS_ARG, QEMU_OPTION_vga, 2156 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n" 2157 " select video card type\n", QEMU_ARCH_ALL) 2158SRST 2159``-vga type`` 2160 Select type of VGA card to emulate. Valid values for type are 2161 2162 ``cirrus`` 2163 Cirrus Logic GD5446 Video card. All Windows versions starting 2164 from Windows 95 should recognize and use this graphic card. For 2165 optimal performances, use 16 bit color depth in the guest and 2166 the host OS. (This card was the default before QEMU 2.2) 2167 2168 ``std`` 2169 Standard VGA card with Bochs VBE extensions. If your guest OS 2170 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if 2171 you want to use high resolution modes (>= 1280x1024x16) then you 2172 should use this option. (This card is the default since QEMU 2173 2.2) 2174 2175 ``vmware`` 2176 VMWare SVGA-II compatible adapter. Use it if you have 2177 sufficiently recent XFree86/XOrg server or Windows guest with a 2178 driver for this card. 2179 2180 ``qxl`` 2181 QXL paravirtual graphic card. It is VGA compatible (including 2182 VESA 2.0 VBE support). Works best with qxl guest drivers 2183 installed though. Recommended choice when using the spice 2184 protocol. 2185 2186 ``tcx`` 2187 (sun4m only) Sun TCX framebuffer. This is the default 2188 framebuffer for sun4m machines and offers both 8-bit and 24-bit 2189 colour depths at a fixed resolution of 1024x768. 2190 2191 ``cg3`` 2192 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit 2193 framebuffer for sun4m machines available in both 1024x768 2194 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people 2195 wishing to run older Solaris versions. 2196 2197 ``virtio`` 2198 Virtio VGA card. 2199 2200 ``none`` 2201 Disable VGA card. 2202ERST 2203 2204DEF("full-screen", 0, QEMU_OPTION_full_screen, 2205 "-full-screen start in full screen\n", QEMU_ARCH_ALL) 2206SRST 2207``-full-screen`` 2208 Start in full screen. 2209ERST 2210 2211DEF("g", HAS_ARG, QEMU_OPTION_g , 2212 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n", 2213 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K) 2214SRST 2215``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]`` 2216 Set the initial graphical resolution and depth (PPC, SPARC only). 2217 2218 For PPC the default is 800x600x32. 2219 2220 For SPARC with the TCX graphics device, the default is 1024x768x8 2221 with the option of 1024x768x24. For cgthree, the default is 2222 1024x768x8 with the option of 1152x900x8 for people who wish to use 2223 OBP. 2224ERST 2225 2226DEF("vnc", HAS_ARG, QEMU_OPTION_vnc , 2227 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL) 2228SRST 2229``-vnc display[,option[,option[,...]]]`` 2230 Normally, if QEMU is compiled with graphical window support, it 2231 displays output such as guest graphics, guest console, and the QEMU 2232 monitor in a window. With this option, you can have QEMU listen on 2233 VNC display display and redirect the VGA display over the VNC 2234 session. It is very useful to enable the usb tablet device when 2235 using this option (option ``-device usb-tablet``). When using the 2236 VNC display, you must use the ``-k`` parameter to set the keyboard 2237 layout if you are not using en-us. Valid syntax for the display is 2238 2239 ``to=L`` 2240 With this option, QEMU will try next available VNC displays, 2241 until the number L, if the origianlly defined "-vnc display" is 2242 not available, e.g. port 5900+display is already used by another 2243 application. By default, to=0. 2244 2245 ``host:d`` 2246 TCP connections will only be allowed from host on display d. By 2247 convention the TCP port is 5900+d. Optionally, host can be 2248 omitted in which case the server will accept connections from 2249 any host. 2250 2251 ``unix:path`` 2252 Connections will be allowed over UNIX domain sockets where path 2253 is the location of a unix socket to listen for connections on. 2254 2255 ``none`` 2256 VNC is initialized but not started. The monitor ``change`` 2257 command can be used to later start the VNC server. 2258 2259 Following the display value there may be one or more option flags 2260 separated by commas. Valid options are 2261 2262 ``reverse=on|off`` 2263 Connect to a listening VNC client via a "reverse" connection. 2264 The client is specified by the display. For reverse network 2265 connections (host:d,``reverse``), the d argument is a TCP port 2266 number, not a display number. 2267 2268 ``websocket=on|off`` 2269 Opens an additional TCP listening port dedicated to VNC 2270 Websocket connections. If a bare websocket option is given, the 2271 Websocket port is 5700+display. An alternative port can be 2272 specified with the syntax ``websocket``\ =port. 2273 2274 If host is specified connections will only be allowed from this 2275 host. It is possible to control the websocket listen address 2276 independently, using the syntax ``websocket``\ =host:port. 2277 2278 If no TLS credentials are provided, the websocket connection 2279 runs in unencrypted mode. If TLS credentials are provided, the 2280 websocket connection requires encrypted client connections. 2281 2282 ``password=on|off`` 2283 Require that password based authentication is used for client 2284 connections. 2285 2286 The password must be set separately using the ``set_password`` 2287 command in the :ref:`QEMU monitor`. The 2288 syntax to change your password is: 2289 ``set_password <protocol> <password>`` where <protocol> could be 2290 either "vnc" or "spice". 2291 2292 If you would like to change <protocol> password expiration, you 2293 should use ``expire_password <protocol> <expiration-time>`` 2294 where expiration time could be one of the following options: 2295 now, never, +seconds or UNIX time of expiration, e.g. +60 to 2296 make password expire in 60 seconds, or 1335196800 to make 2297 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for 2298 this date and time). 2299 2300 You can also use keywords "now" or "never" for the expiration 2301 time to allow <protocol> password to expire immediately or never 2302 expire. 2303 2304 ``password-secret=<secret-id>`` 2305 Require that password based authentication is used for client 2306 connections, using the password provided by the ``secret`` 2307 object identified by ``secret-id``. 2308 2309 ``tls-creds=ID`` 2310 Provides the ID of a set of TLS credentials to use to secure the 2311 VNC server. They will apply to both the normal VNC server socket 2312 and the websocket socket (if enabled). Setting TLS credentials 2313 will cause the VNC server socket to enable the VeNCrypt auth 2314 mechanism. The credentials should have been previously created 2315 using the ``-object tls-creds`` argument. 2316 2317 ``tls-authz=ID`` 2318 Provides the ID of the QAuthZ authorization object against which 2319 the client's x509 distinguished name will validated. This object 2320 is only resolved at time of use, so can be deleted and recreated 2321 on the fly while the VNC server is active. If missing, it will 2322 default to denying access. 2323 2324 ``sasl=on|off`` 2325 Require that the client use SASL to authenticate with the VNC 2326 server. The exact choice of authentication method used is 2327 controlled from the system / user's SASL configuration file for 2328 the 'qemu' service. This is typically found in 2329 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, 2330 an environment variable SASL\_CONF\_PATH can be used to make it 2331 search alternate locations for the service config. While some 2332 SASL auth methods can also provide data encryption (eg GSSAPI), 2333 it is recommended that SASL always be combined with the 'tls' 2334 and 'x509' settings to enable use of SSL and server 2335 certificates. This ensures a data encryption preventing 2336 compromise of authentication credentials. See the 2337 :ref:`VNC security` section in the System Emulation Users Guide 2338 for details on using SASL authentication. 2339 2340 ``sasl-authz=ID`` 2341 Provides the ID of the QAuthZ authorization object against which 2342 the client's SASL username will validated. This object is only 2343 resolved at time of use, so can be deleted and recreated on the 2344 fly while the VNC server is active. If missing, it will default 2345 to denying access. 2346 2347 ``acl=on|off`` 2348 Legacy method for enabling authorization of clients against the 2349 x509 distinguished name and SASL username. It results in the 2350 creation of two ``authz-list`` objects with IDs of 2351 ``vnc.username`` and ``vnc.x509dname``. The rules for these 2352 objects must be configured with the HMP ACL commands. 2353 2354 This option is deprecated and should no longer be used. The new 2355 ``sasl-authz`` and ``tls-authz`` options are a replacement. 2356 2357 ``lossy=on|off`` 2358 Enable lossy compression methods (gradient, JPEG, ...). If this 2359 option is set, VNC client may receive lossy framebuffer updates 2360 depending on its encoding settings. Enabling this option can 2361 save a lot of bandwidth at the expense of quality. 2362 2363 ``non-adaptive=on|off`` 2364 Disable adaptive encodings. Adaptive encodings are enabled by 2365 default. An adaptive encoding will try to detect frequently 2366 updated screen regions, and send updates in these regions using 2367 a lossy encoding (like JPEG). This can be really helpful to save 2368 bandwidth when playing videos. Disabling adaptive encodings 2369 restores the original static behavior of encodings like Tight. 2370 2371 ``share=[allow-exclusive|force-shared|ignore]`` 2372 Set display sharing policy. 'allow-exclusive' allows clients to 2373 ask for exclusive access. As suggested by the rfb spec this is 2374 implemented by dropping other connections. Connecting multiple 2375 clients in parallel requires all clients asking for a shared 2376 session (vncviewer: -shared switch). This is the default. 2377 'force-shared' disables exclusive client access. Useful for 2378 shared desktop sessions, where you don't want someone forgetting 2379 specify -shared disconnect everybody else. 'ignore' completely 2380 ignores the shared flag and allows everybody connect 2381 unconditionally. Doesn't conform to the rfb spec but is 2382 traditional QEMU behavior. 2383 2384 ``key-delay-ms`` 2385 Set keyboard delay, for key down and key up events, in 2386 milliseconds. Default is 10. Keyboards are low-bandwidth 2387 devices, so this slowdown can help the device and guest to keep 2388 up and not lose events in case events are arriving in bulk. 2389 Possible causes for the latter are flaky network connections, or 2390 scripts for automated testing. 2391 2392 ``audiodev=audiodev`` 2393 Use the specified audiodev when the VNC client requests audio 2394 transmission. When not using an -audiodev argument, this option 2395 must be omitted, otherwise is must be present and specify a 2396 valid audiodev. 2397 2398 ``power-control=on|off`` 2399 Permit the remote client to issue shutdown, reboot or reset power 2400 control requests. 2401ERST 2402 2403ARCHHEADING(, QEMU_ARCH_I386) 2404 2405ARCHHEADING(i386 target only:, QEMU_ARCH_I386) 2406 2407DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack, 2408 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n", 2409 QEMU_ARCH_I386) 2410SRST 2411``-win2k-hack`` 2412 Use it when installing Windows 2000 to avoid a disk full bug. After 2413 Windows 2000 is installed, you no longer need this option (this 2414 option slows down the IDE transfers). 2415ERST 2416 2417DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk, 2418 "-no-fd-bootchk disable boot signature checking for floppy disks\n", 2419 QEMU_ARCH_I386) 2420SRST 2421``-no-fd-bootchk`` 2422 Disable boot signature checking for floppy disks in BIOS. May be 2423 needed to boot from old floppy disks. 2424ERST 2425 2426DEF("no-acpi", 0, QEMU_OPTION_no_acpi, 2427 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2428SRST 2429``-no-acpi`` 2430 Disable ACPI (Advanced Configuration and Power Interface) support. 2431 Use it if your guest OS complains about ACPI problems (PC target 2432 machine only). 2433ERST 2434 2435DEF("no-hpet", 0, QEMU_OPTION_no_hpet, 2436 "-no-hpet disable HPET\n", QEMU_ARCH_I386) 2437SRST 2438``-no-hpet`` 2439 Disable HPET support. 2440ERST 2441 2442DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable, 2443 "-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" 2444 " ACPI table description\n", QEMU_ARCH_I386) 2445SRST 2446``-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]...]`` 2447 Add ACPI table with specified header fields and context from 2448 specified files. For file=, take whole ACPI table from the specified 2449 files, including all ACPI headers (possible overridden by other 2450 options). For data=, only data portion of the table is used, all 2451 header information is specified in the command line. If a SLIC table 2452 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id 2453 fields will override the same in the RSDT and the FADT (a.k.a. 2454 FACP), in order to ensure the field matches required by the 2455 Microsoft SLIC spec and the ACPI spec. 2456ERST 2457 2458DEF("smbios", HAS_ARG, QEMU_OPTION_smbios, 2459 "-smbios file=binary\n" 2460 " load SMBIOS entry from binary file\n" 2461 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n" 2462 " [,uefi=on|off]\n" 2463 " specify SMBIOS type 0 fields\n" 2464 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2465 " [,uuid=uuid][,sku=str][,family=str]\n" 2466 " specify SMBIOS type 1 fields\n" 2467 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2468 " [,asset=str][,location=str]\n" 2469 " specify SMBIOS type 2 fields\n" 2470 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n" 2471 " [,sku=str]\n" 2472 " specify SMBIOS type 3 fields\n" 2473 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n" 2474 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n" 2475 " specify SMBIOS type 4 fields\n" 2476 "-smbios type=11[,value=str][,path=filename]\n" 2477 " specify SMBIOS type 11 fields\n" 2478 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n" 2479 " [,asset=str][,part=str][,speed=%d]\n" 2480 " specify SMBIOS type 17 fields\n" 2481 "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n" 2482 " specify SMBIOS type 41 fields\n", 2483 QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2484SRST 2485``-smbios file=binary`` 2486 Load SMBIOS entry from binary file. 2487 2488``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]`` 2489 Specify SMBIOS type 0 fields 2490 2491``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]`` 2492 Specify SMBIOS type 1 fields 2493 2494``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]`` 2495 Specify SMBIOS type 2 fields 2496 2497``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]`` 2498 Specify SMBIOS type 3 fields 2499 2500``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str]`` 2501 Specify SMBIOS type 4 fields 2502 2503``-smbios type=11[,value=str][,path=filename]`` 2504 Specify SMBIOS type 11 fields 2505 2506 This argument can be repeated multiple times, and values are added in the order they are parsed. 2507 Applications intending to use OEM strings data are encouraged to use their application name as 2508 a prefix for the value string. This facilitates passing information for multiple applications 2509 concurrently. 2510 2511 The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax 2512 loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes. 2513 2514 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to 2515 the SMBIOS table in the order in which they appear. 2516 2517 Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535 2518 bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the 2519 guest. Instead it should be used as a indicator to inform the guest where to locate the real 2520 data set, for example, by specifying the serial ID of a block device. 2521 2522 An example passing three strings is 2523 2524 .. parsed-literal:: 2525 2526 -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\ 2527 value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\ 2528 path=/some/file/with/oemstringsdata.txt 2529 2530 In the guest OS this is visible with the ``dmidecode`` command 2531 2532 .. parsed-literal:: 2533 2534 $ dmidecode -t 11 2535 Handle 0x0E00, DMI type 11, 5 bytes 2536 OEM Strings 2537 String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/ 2538 String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os 2539 String 3: myapp:some extra data 2540 2541 2542``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]`` 2543 Specify SMBIOS type 17 fields 2544 2545``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]`` 2546 Specify SMBIOS type 41 fields 2547 2548 This argument can be repeated multiple times. Its main use is to allow network interfaces be created 2549 as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface 2550 position on the PCI bus. 2551 2552 Here is an example of use: 2553 2554 .. parsed-literal:: 2555 2556 -netdev user,id=internet \\ 2557 -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\ 2558 -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev 2559 2560 In the guest OS, the device should then appear as ``eno1``: 2561 2562 ..parsed-literal:: 2563 2564 $ ip -brief l 2565 lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP> 2566 eno1 UP 50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP> 2567 2568 Currently, the PCI device has to be attached to the root bus. 2569 2570ERST 2571 2572DEFHEADING() 2573 2574DEFHEADING(Network options:) 2575 2576DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, 2577#ifdef CONFIG_SLIRP 2578 "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n" 2579 " [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n" 2580 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n" 2581 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n" 2582 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]" 2583#ifndef _WIN32 2584 "[,smb=dir[,smbserver=addr]]\n" 2585#endif 2586 " configure a user mode network backend with ID 'str',\n" 2587 " its DHCP server and optional services\n" 2588#endif 2589#ifdef _WIN32 2590 "-netdev tap,id=str,ifname=name\n" 2591 " configure a host TAP network backend with ID 'str'\n" 2592#else 2593 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n" 2594 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" 2595 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" 2596 " [,poll-us=n]\n" 2597 " configure a host TAP network backend with ID 'str'\n" 2598 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2599 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n" 2600 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n" 2601 " to deconfigure it\n" 2602 " use '[down]script=no' to disable script execution\n" 2603 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n" 2604 " configure it\n" 2605 " use 'fd=h' to connect to an already opened TAP interface\n" 2606 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n" 2607 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n" 2608 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n" 2609 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" 2610 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" 2611 " use vhost=on to enable experimental in kernel accelerator\n" 2612 " (only has effect for virtio guests which use MSIX)\n" 2613 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" 2614 " use 'vhostfd=h' to connect to an already opened vhost net device\n" 2615 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n" 2616 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n" 2617 " use 'poll-us=n' to specify the maximum number of microseconds that could be\n" 2618 " spent on busy polling for vhost net\n" 2619 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n" 2620 " configure a host TAP network backend with ID 'str' that is\n" 2621 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2622 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n" 2623#endif 2624#ifdef __linux__ 2625 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n" 2626 " [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n" 2627 " [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n" 2628 " [,rxcookie=rxcookie][,offset=offset]\n" 2629 " configure a network backend with ID 'str' connected to\n" 2630 " an Ethernet over L2TPv3 pseudowire.\n" 2631 " Linux kernel 3.3+ as well as most routers can talk\n" 2632 " L2TPv3. This transport allows connecting a VM to a VM,\n" 2633 " VM to a router and even VM to Host. It is a nearly-universal\n" 2634 " standard (RFC3931). Note - this implementation uses static\n" 2635 " pre-configured tunnels (same as the Linux kernel).\n" 2636 " use 'src=' to specify source address\n" 2637 " use 'dst=' to specify destination address\n" 2638 " use 'udp=on' to specify udp encapsulation\n" 2639 " use 'srcport=' to specify source udp port\n" 2640 " use 'dstport=' to specify destination udp port\n" 2641 " use 'ipv6=on' to force v6\n" 2642 " L2TPv3 uses cookies to prevent misconfiguration as\n" 2643 " well as a weak security measure\n" 2644 " use 'rxcookie=0x012345678' to specify a rxcookie\n" 2645 " use 'txcookie=0x012345678' to specify a txcookie\n" 2646 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n" 2647 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n" 2648 " use 'pincounter=on' to work around broken counter handling in peer\n" 2649 " use 'offset=X' to add an extra offset between header and data\n" 2650#endif 2651 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n" 2652 " configure a network backend to connect to another network\n" 2653 " using a socket connection\n" 2654 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n" 2655 " configure a network backend to connect to a multicast maddr and port\n" 2656 " use 'localaddr=addr' to specify the host address to send packets from\n" 2657 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n" 2658 " configure a network backend to connect to another network\n" 2659 " using an UDP tunnel\n" 2660#ifdef CONFIG_VDE 2661 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n" 2662 " configure a network backend to connect to port 'n' of a vde switch\n" 2663 " running on host and listening for incoming connections on 'socketpath'.\n" 2664 " Use group 'groupname' and mode 'octalmode' to change default\n" 2665 " ownership and permissions for communication port.\n" 2666#endif 2667#ifdef CONFIG_NETMAP 2668 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n" 2669 " attach to the existing netmap-enabled network interface 'name', or to a\n" 2670 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n" 2671 " netmap device, defaults to '/dev/netmap')\n" 2672#endif 2673#ifdef CONFIG_POSIX 2674 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" 2675 " configure a vhost-user network, backed by a chardev 'dev'\n" 2676#endif 2677#ifdef __linux__ 2678 "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n" 2679 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n" 2680#endif 2681 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n" 2682 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL) 2683DEF("nic", HAS_ARG, QEMU_OPTION_nic, 2684 "-nic [tap|bridge|" 2685#ifdef CONFIG_SLIRP 2686 "user|" 2687#endif 2688#ifdef __linux__ 2689 "l2tpv3|" 2690#endif 2691#ifdef CONFIG_VDE 2692 "vde|" 2693#endif 2694#ifdef CONFIG_NETMAP 2695 "netmap|" 2696#endif 2697#ifdef CONFIG_POSIX 2698 "vhost-user|" 2699#endif 2700 "socket][,option][,...][mac=macaddr]\n" 2701 " initialize an on-board / default host NIC (using MAC address\n" 2702 " macaddr) and connect it to the given host network backend\n" 2703 "-nic none use it alone to have zero network devices (the default is to\n" 2704 " provided a 'user' network connection)\n", 2705 QEMU_ARCH_ALL) 2706DEF("net", HAS_ARG, QEMU_OPTION_net, 2707 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" 2708 " configure or create an on-board (or machine default) NIC and\n" 2709 " connect it to hub 0 (please use -nic unless you need a hub)\n" 2710 "-net [" 2711#ifdef CONFIG_SLIRP 2712 "user|" 2713#endif 2714 "tap|" 2715 "bridge|" 2716#ifdef CONFIG_VDE 2717 "vde|" 2718#endif 2719#ifdef CONFIG_NETMAP 2720 "netmap|" 2721#endif 2722 "socket][,option][,option][,...]\n" 2723 " old way to initialize a host network interface\n" 2724 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL) 2725SRST 2726``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]`` 2727 This option is a shortcut for configuring both the on-board 2728 (default) guest NIC hardware and the host network backend in one go. 2729 The host backend options are the same as with the corresponding 2730 ``-netdev`` options below. The guest NIC model can be set with 2731 ``model=modelname``. Use ``model=help`` to list the available device 2732 types. The hardware MAC address can be set with ``mac=macaddr``. 2733 2734 The following two example do exactly the same, to show how ``-nic`` 2735 can be used to shorten the command line length: 2736 2737 .. parsed-literal:: 2738 2739 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32 2740 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32 2741 2742``-nic none`` 2743 Indicate that no network devices should be configured. It is used to 2744 override the default configuration (default NIC with "user" host 2745 network backend) which is activated if no other networking options 2746 are provided. 2747 2748``-netdev user,id=id[,option][,option][,...]`` 2749 Configure user mode host network backend which requires no 2750 administrator privilege to run. Valid options are: 2751 2752 ``id=id`` 2753 Assign symbolic name for use in monitor commands. 2754 2755 ``ipv4=on|off and ipv6=on|off`` 2756 Specify that either IPv4 or IPv6 must be enabled. If neither is 2757 specified both protocols are enabled. 2758 2759 ``net=addr[/mask]`` 2760 Set IP network address the guest will see. Optionally specify 2761 the netmask, either in the form a.b.c.d or as number of valid 2762 top-most bits. Default is 10.0.2.0/24. 2763 2764 ``host=addr`` 2765 Specify the guest-visible address of the host. Default is the 2766 2nd IP in the guest network, i.e. x.x.x.2. 2767 2768 ``ipv6-net=addr[/int]`` 2769 Set IPv6 network address the guest will see (default is 2770 fec0::/64). The network prefix is given in the usual hexadecimal 2771 IPv6 address notation. The prefix size is optional, and is given 2772 as the number of valid top-most bits (default is 64). 2773 2774 ``ipv6-host=addr`` 2775 Specify the guest-visible IPv6 address of the host. Default is 2776 the 2nd IPv6 in the guest network, i.e. xxxx::2. 2777 2778 ``restrict=on|off`` 2779 If this option is enabled, the guest will be isolated, i.e. it 2780 will not be able to contact the host and no guest IP packets 2781 will be routed over the host to the outside. This option does 2782 not affect any explicitly set forwarding rules. 2783 2784 ``hostname=name`` 2785 Specifies the client hostname reported by the built-in DHCP 2786 server. 2787 2788 ``dhcpstart=addr`` 2789 Specify the first of the 16 IPs the built-in DHCP server can 2790 assign. Default is the 15th to 31st IP in the guest network, 2791 i.e. x.x.x.15 to x.x.x.31. 2792 2793 ``dns=addr`` 2794 Specify the guest-visible address of the virtual nameserver. The 2795 address must be different from the host address. Default is the 2796 3rd IP in the guest network, i.e. x.x.x.3. 2797 2798 ``ipv6-dns=addr`` 2799 Specify the guest-visible address of the IPv6 virtual 2800 nameserver. The address must be different from the host address. 2801 Default is the 3rd IP in the guest network, i.e. xxxx::3. 2802 2803 ``dnssearch=domain`` 2804 Provides an entry for the domain-search list sent by the 2805 built-in DHCP server. More than one domain suffix can be 2806 transmitted by specifying this option multiple times. If 2807 supported, this will cause the guest to automatically try to 2808 append the given domain suffix(es) in case a domain name can not 2809 be resolved. 2810 2811 Example: 2812 2813 .. parsed-literal:: 2814 2815 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org 2816 2817 ``domainname=domain`` 2818 Specifies the client domain name reported by the built-in DHCP 2819 server. 2820 2821 ``tftp=dir`` 2822 When using the user mode network stack, activate a built-in TFTP 2823 server. The files in dir will be exposed as the root of a TFTP 2824 server. The TFTP client on the guest must be configured in 2825 binary mode (use the command ``bin`` of the Unix TFTP client). 2826 2827 ``tftp-server-name=name`` 2828 In BOOTP reply, broadcast name as the "TFTP server name" 2829 (RFC2132 option 66). This can be used to advise the guest to 2830 load boot files or configurations from a different server than 2831 the host address. 2832 2833 ``bootfile=file`` 2834 When using the user mode network stack, broadcast file as the 2835 BOOTP filename. In conjunction with ``tftp``, this can be used 2836 to network boot a guest from a local directory. 2837 2838 Example (using pxelinux): 2839 2840 .. parsed-literal:: 2841 2842 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\ 2843 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0 2844 2845 ``smb=dir[,smbserver=addr]`` 2846 When using the user mode network stack, activate a built-in SMB 2847 server so that Windows OSes can access to the host files in 2848 ``dir`` transparently. The IP address of the SMB server can be 2849 set to addr. By default the 4th IP in the guest network is used, 2850 i.e. x.x.x.4. 2851 2852 In the guest Windows OS, the line: 2853 2854 :: 2855 2856 10.0.2.4 smbserver 2857 2858 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows 2859 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows 2860 NT/2000). 2861 2862 Then ``dir`` can be accessed in ``\\smbserver\qemu``. 2863 2864 Note that a SAMBA server must be installed on the host OS. 2865 2866 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport`` 2867 Redirect incoming TCP or UDP connections to the host port 2868 hostport to the guest IP address guestaddr on guest port 2869 guestport. If guestaddr is not specified, its value is x.x.x.15 2870 (default first address given by the built-in DHCP server). By 2871 specifying hostaddr, the rule can be bound to a specific host 2872 interface. If no connection type is set, TCP is used. This 2873 option can be given multiple times. 2874 2875 For example, to redirect host X11 connection from screen 1 to 2876 guest screen 0, use the following: 2877 2878 .. parsed-literal:: 2879 2880 # on the host 2881 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000 2882 # this host xterm should open in the guest X11 server 2883 xterm -display :1 2884 2885 To redirect telnet connections from host port 5555 to telnet 2886 port on the guest, use the following: 2887 2888 .. parsed-literal:: 2889 2890 # on the host 2891 |qemu_system| -nic user,hostfwd=tcp::5555-:23 2892 telnet localhost 5555 2893 2894 Then when you use on the host ``telnet localhost 5555``, you 2895 connect to the guest telnet server. 2896 2897 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command`` 2898 Forward guest TCP connections to the IP address server on port 2899 port to the character device dev or to a program executed by 2900 cmd:command which gets spawned for each connection. This option 2901 can be given multiple times. 2902 2903 You can either use a chardev directly and have that one used 2904 throughout QEMU's lifetime, like in the following example: 2905 2906 .. parsed-literal:: 2907 2908 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever 2909 # the guest accesses it 2910 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 2911 2912 Or you can execute a command on every TCP connection established 2913 by the guest, so that QEMU behaves similar to an inetd process 2914 for that virtual server: 2915 2916 .. parsed-literal:: 2917 2918 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234 2919 # and connect the TCP stream to its stdin/stdout 2920 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321' 2921 2922``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]`` 2923 Configure a host TAP network backend with ID id. 2924 2925 Use the network script file to configure it and the network script 2926 dfile to deconfigure it. If name is not provided, the OS 2927 automatically provides one. The default network configure script is 2928 ``/etc/qemu-ifup`` and the default network deconfigure script is 2929 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to 2930 disable script execution. 2931 2932 If running QEMU as an unprivileged user, use the network helper 2933 to configure the TAP interface and attach it to the bridge. 2934 The default network helper executable is 2935 ``/path/to/qemu-bridge-helper`` and the default bridge device is 2936 ``br0``. 2937 2938 ``fd``\ =h can be used to specify the handle of an already opened 2939 host TAP interface. 2940 2941 Examples: 2942 2943 .. parsed-literal:: 2944 2945 #launch a QEMU instance with the default network script 2946 |qemu_system| linux.img -nic tap 2947 2948 .. parsed-literal:: 2949 2950 #launch a QEMU instance with two NICs, each one connected 2951 #to a TAP device 2952 |qemu_system| linux.img \\ 2953 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\ 2954 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1 2955 2956 .. parsed-literal:: 2957 2958 #launch a QEMU instance with the default network helper to 2959 #connect a TAP device to bridge br0 2960 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\ 2961 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper" 2962 2963``-netdev bridge,id=id[,br=bridge][,helper=helper]`` 2964 Connect a host TAP network interface to a host bridge device. 2965 2966 Use the network helper helper to configure the TAP interface and 2967 attach it to the bridge. The default network helper executable is 2968 ``/path/to/qemu-bridge-helper`` and the default bridge device is 2969 ``br0``. 2970 2971 Examples: 2972 2973 .. parsed-literal:: 2974 2975 #launch a QEMU instance with the default network helper to 2976 #connect a TAP device to bridge br0 2977 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1 2978 2979 .. parsed-literal:: 2980 2981 #launch a QEMU instance with the default network helper to 2982 #connect a TAP device to bridge qemubr0 2983 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1 2984 2985``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]`` 2986 This host network backend can be used to connect the guest's network 2987 to another QEMU virtual machine using a TCP socket connection. If 2988 ``listen`` is specified, QEMU waits for incoming connections on port 2989 (host is optional). ``connect`` is used to connect to another QEMU 2990 instance using the ``listen`` option. ``fd``\ =h specifies an 2991 already opened TCP socket. 2992 2993 Example: 2994 2995 .. parsed-literal:: 2996 2997 # launch a first QEMU instance 2998 |qemu_system| linux.img \\ 2999 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3000 -netdev socket,id=n1,listen=:1234 3001 # connect the network of this instance to the network of the first instance 3002 |qemu_system| linux.img \\ 3003 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3004 -netdev socket,id=n2,connect=127.0.0.1:1234 3005 3006``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]`` 3007 Configure a socket host network backend to share the guest's network 3008 traffic with another QEMU virtual machines using a UDP multicast 3009 socket, effectively making a bus for every QEMU with same multicast 3010 address maddr and port. NOTES: 3011 3012 1. Several QEMU can be running on different hosts and share same bus 3013 (assuming correct multicast setup for these hosts). 3014 3015 2. mcast support is compatible with User Mode Linux (argument 3016 ``ethN=mcast``), see http://user-mode-linux.sf.net. 3017 3018 3. Use ``fd=h`` to specify an already opened UDP multicast socket. 3019 3020 Example: 3021 3022 .. parsed-literal:: 3023 3024 # launch one QEMU instance 3025 |qemu_system| linux.img \\ 3026 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3027 -netdev socket,id=n1,mcast=230.0.0.1:1234 3028 # launch another QEMU instance on same "bus" 3029 |qemu_system| linux.img \\ 3030 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3031 -netdev socket,id=n2,mcast=230.0.0.1:1234 3032 # launch yet another QEMU instance on same "bus" 3033 |qemu_system| linux.img \\ 3034 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\ 3035 -netdev socket,id=n3,mcast=230.0.0.1:1234 3036 3037 Example (User Mode Linux compat.): 3038 3039 .. parsed-literal:: 3040 3041 # launch QEMU instance (note mcast address selected is UML's default) 3042 |qemu_system| linux.img \\ 3043 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3044 -netdev socket,id=n1,mcast=239.192.168.1:1102 3045 # launch UML 3046 /path/to/linux ubd0=/path/to/root_fs eth0=mcast 3047 3048 Example (send packets from host's 1.2.3.4): 3049 3050 .. parsed-literal:: 3051 3052 |qemu_system| linux.img \\ 3053 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3054 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4 3055 3056``-netdev l2tpv3,id=id,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport],txsession=txsession[,rxsession=rxsession][,ipv6=on|off][,udp=on|off][,cookie64][,counter][,pincounter][,txcookie=txcookie][,rxcookie=rxcookie][,offset=offset]`` 3057 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931) 3058 is a popular protocol to transport Ethernet (and other Layer 2) data 3059 frames between two systems. It is present in routers, firewalls and 3060 the Linux kernel (from version 3.3 onwards). 3061 3062 This transport allows a VM to communicate to another VM, router or 3063 firewall directly. 3064 3065 ``src=srcaddr`` 3066 source address (mandatory) 3067 3068 ``dst=dstaddr`` 3069 destination address (mandatory) 3070 3071 ``udp`` 3072 select udp encapsulation (default is ip). 3073 3074 ``srcport=srcport`` 3075 source udp port. 3076 3077 ``dstport=dstport`` 3078 destination udp port. 3079 3080 ``ipv6`` 3081 force v6, otherwise defaults to v4. 3082 3083 ``rxcookie=rxcookie``; \ ``txcookie=txcookie`` 3084 Cookies are a weak form of security in the l2tpv3 specification. 3085 Their function is mostly to prevent misconfiguration. By default 3086 they are 32 bit. 3087 3088 ``cookie64`` 3089 Set cookie size to 64 bit instead of the default 32 3090 3091 ``counter=off`` 3092 Force a 'cut-down' L2TPv3 with no counter as in 3093 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00 3094 3095 ``pincounter=on`` 3096 Work around broken counter handling in peer. This may also help 3097 on networks which have packet reorder. 3098 3099 ``offset=offset`` 3100 Add an extra offset between header and data 3101 3102 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to 3103 the bridge br-lan on the remote Linux host 1.2.3.4: 3104 3105 .. parsed-literal:: 3106 3107 # Setup tunnel on linux host using raw ip as encapsulation 3108 # on 1.2.3.4 3109 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\ 3110 encap udp udp_sport 16384 udp_dport 16384 3111 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\ 3112 0xFFFFFFFF peer_session_id 0xFFFFFFFF 3113 ifconfig vmtunnel0 mtu 1500 3114 ifconfig vmtunnel0 up 3115 brctl addif br-lan vmtunnel0 3116 3117 3118 # on 4.3.2.1 3119 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter 3120 3121 |qemu_system| linux.img -device e1000,netdev=n1 \\ 3122 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter 3123 3124``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]`` 3125 Configure VDE backend to connect to PORT n of a vde switch running 3126 on host and listening for incoming connections on socketpath. Use 3127 GROUP groupname and MODE octalmode to change default ownership and 3128 permissions for communication port. This option is only available if 3129 QEMU has been compiled with vde support enabled. 3130 3131 Example: 3132 3133 .. parsed-literal:: 3134 3135 # launch vde switch 3136 vde_switch -F -sock /tmp/myswitch 3137 # launch QEMU instance 3138 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch 3139 3140``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]`` 3141 Establish a vhost-user netdev, backed by a chardev id. The chardev 3142 should be a unix domain socket backed one. The vhost-user uses a 3143 specifically defined protocol to pass vhost ioctl replacement 3144 messages to an application on the other end of the socket. On 3145 non-MSIX guests, the feature can be forced with vhostforce. Use 3146 'queues=n' to specify the number of queues to be created for 3147 multiqueue vhost-user. 3148 3149 Example: 3150 3151 :: 3152 3153 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \ 3154 -numa node,memdev=mem \ 3155 -chardev socket,id=chr0,path=/path/to/socket \ 3156 -netdev type=vhost-user,id=net0,chardev=chr0 \ 3157 -device virtio-net-pci,netdev=net0 3158 3159``-netdev vhost-vdpa,vhostdev=/path/to/dev`` 3160 Establish a vhost-vdpa netdev. 3161 3162 vDPA device is a device that uses a datapath which complies with 3163 the virtio specifications with a vendor specific control path. 3164 vDPA devices can be both physically located on the hardware or 3165 emulated by software. 3166 3167``-netdev hubport,id=id,hubid=hubid[,netdev=nd]`` 3168 Create a hub port on the emulated hub with ID hubid. 3169 3170 The hubport netdev lets you connect a NIC to a QEMU emulated hub 3171 instead of a single netdev. Alternatively, you can also connect the 3172 hubport to another netdev with ID nd by using the ``netdev=nd`` 3173 option. 3174 3175``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]`` 3176 Legacy option to configure or create an on-board (or machine 3177 default) Network Interface Card(NIC) and connect it either to the 3178 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd. 3179 If model is omitted, then the default NIC model associated with the 3180 machine type is used. Note that the default NIC model may change in 3181 future QEMU releases, so it is highly recommended to always specify 3182 a model. Optionally, the MAC address can be changed to mac, the 3183 device address set to addr (PCI cards only), and a name can be 3184 assigned for use in monitor commands. Optionally, for PCI cards, you 3185 can specify the number v of MSI-X vectors that the card should have; 3186 this option currently only affects virtio cards; set v = 0 to 3187 disable MSI-X. If no ``-net`` option is specified, a single NIC is 3188 created. QEMU can emulate several different models of network card. 3189 Use ``-net nic,model=help`` for a list of available devices for your 3190 target. 3191 3192``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]`` 3193 Configure a host network backend (with the options corresponding to 3194 the same ``-netdev`` option) and connect it to the emulated hub 0 3195 (the default hub). Use name to specify the name of the hub port. 3196ERST 3197 3198DEFHEADING() 3199 3200DEFHEADING(Character device options:) 3201 3202DEF("chardev", HAS_ARG, QEMU_OPTION_chardev, 3203 "-chardev help\n" 3204 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3205 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n" 3206 " [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n" 3207 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n" 3208 "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n" 3209 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n" 3210 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n" 3211 " [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n" 3212 " [,logfile=PATH][,logappend=on|off]\n" 3213 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3214 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n" 3215 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3216 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n" 3217 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3218 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3219#ifdef _WIN32 3220 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3221 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3222#else 3223 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3224 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n" 3225#endif 3226#ifdef CONFIG_BRLAPI 3227 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3228#endif 3229#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ 3230 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) 3231 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3232 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3233#endif 3234#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__) 3235 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3236 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3237#endif 3238#if defined(CONFIG_SPICE) 3239 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3240 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3241#endif 3242 , QEMU_ARCH_ALL 3243) 3244 3245SRST 3246The general form of a character device option is: 3247 3248``-chardev backend,id=id[,mux=on|off][,options]`` 3249 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, 3250 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``, 3251 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``, 3252 ``spicevmc``, ``spiceport``. The specific backend will determine the 3253 applicable options. 3254 3255 Use ``-chardev help`` to print all available chardev backend types. 3256 3257 All devices must have an id, which can be any string up to 127 3258 characters long. It is used to uniquely identify this device in 3259 other command line directives. 3260 3261 A character device may be used in multiplexing mode by multiple 3262 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is 3263 a "1:N" device, and here the "1" end is your specified chardev 3264 backend, and the "N" end is the various parts of QEMU that can talk 3265 to a chardev. If you create a chardev with ``id=myid`` and 3266 ``mux=on``, QEMU will create a multiplexer with your specified ID, 3267 and you can then configure multiple front ends to use that chardev 3268 ID for their input/output. Up to four different front ends can be 3269 connected to a single multiplexed chardev. (Without multiplexing 3270 enabled, a chardev can only be used by a single front end.) For 3271 instance you could use this to allow a single stdio chardev to be 3272 used by two serial ports and the QEMU monitor: 3273 3274 :: 3275 3276 -chardev stdio,mux=on,id=char0 \ 3277 -mon chardev=char0,mode=readline \ 3278 -serial chardev:char0 \ 3279 -serial chardev:char0 3280 3281 You can have more than one multiplexer in a system configuration; 3282 for instance you could have a TCP port multiplexed between UART 0 3283 and UART 1, and stdio multiplexed between the QEMU monitor and a 3284 parallel port: 3285 3286 :: 3287 3288 -chardev stdio,mux=on,id=char0 \ 3289 -mon chardev=char0,mode=readline \ 3290 -parallel chardev:char0 \ 3291 -chardev tcp,...,mux=on,id=char1 \ 3292 -serial chardev:char1 \ 3293 -serial chardev:char1 3294 3295 When you're using a multiplexed character device, some escape 3296 sequences are interpreted in the input. See the chapter about 3297 :ref:`keys in the character backend multiplexer` in the 3298 System Emulation Users Guide for more details. 3299 3300 Note that some other command line options may implicitly create 3301 multiplexed character backends; for instance ``-serial mon:stdio`` 3302 creates a multiplexed stdio backend connected to the serial port and 3303 the QEMU monitor, and ``-nographic`` also multiplexes the console 3304 and the monitor to stdio. 3305 3306 There is currently no support for multiplexing in the other 3307 direction (where a single QEMU front end takes input and output from 3308 multiple chardevs). 3309 3310 Every backend supports the ``logfile`` option, which supplies the 3311 path to a file to record all data transmitted via the backend. The 3312 ``logappend`` option controls whether the log file will be truncated 3313 or appended to when opened. 3314 3315The available backends are: 3316 3317``-chardev null,id=id`` 3318 A void device. This device will not emit any data, and will drop any 3319 data it receives. The null backend does not take any options. 3320 3321``-chardev socket,id=id[,TCP options or unix options][,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,tls-creds=id][,tls-authz=id]`` 3322 Create a two-way stream socket, which can be either a TCP or a unix 3323 socket. A unix socket will be created if ``path`` is specified. 3324 Behaviour is undefined if TCP options are specified for a unix 3325 socket. 3326 3327 ``server=on|off`` specifies that the socket shall be a listening socket. 3328 3329 ``wait=on|off`` specifies that QEMU should not block waiting for a client 3330 to connect to a listening socket. 3331 3332 ``telnet=on|off`` specifies that traffic on the socket should interpret 3333 telnet escape sequences. 3334 3335 ``websocket=on|off`` specifies that the socket uses WebSocket protocol for 3336 communication. 3337 3338 ``reconnect`` sets the timeout for reconnecting on non-server 3339 sockets when the remote end goes away. qemu will delay this many 3340 seconds and then attempt to reconnect. Zero disables reconnecting, 3341 and is the default. 3342 3343 ``tls-creds`` requests enablement of the TLS protocol for 3344 encryption, and specifies the id of the TLS credentials to use for 3345 the handshake. The credentials must be previously created with the 3346 ``-object tls-creds`` argument. 3347 3348 ``tls-auth`` provides the ID of the QAuthZ authorization object 3349 against which the client's x509 distinguished name will be 3350 validated. This object is only resolved at time of use, so can be 3351 deleted and recreated on the fly while the chardev server is active. 3352 If missing, it will default to denying access. 3353 3354 TCP and unix socket options are given below: 3355 3356 ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]`` 3357 ``host`` for a listening socket specifies the local address to 3358 be bound. For a connecting socket species the remote host to 3359 connect to. ``host`` is optional for listening sockets. If not 3360 specified it defaults to ``0.0.0.0``. 3361 3362 ``port`` for a listening socket specifies the local port to be 3363 bound. For a connecting socket specifies the port on the remote 3364 host to connect to. ``port`` can be given as either a port 3365 number or a service name. ``port`` is required. 3366 3367 ``to`` is only relevant to listening sockets. If it is 3368 specified, and ``port`` cannot be bound, QEMU will attempt to 3369 bind to subsequent ports up to and including ``to`` until it 3370 succeeds. ``to`` must be specified as a port number. 3371 3372 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 3373 or IPv6 must be used. If neither is specified the socket may 3374 use either protocol. 3375 3376 ``nodelay=on|off`` disables the Nagle algorithm. 3377 3378 ``unix options: path=path[,abstract=on|off][,tight=on|off]`` 3379 ``path`` specifies the local path of the unix socket. ``path`` 3380 is required. 3381 ``abstract=on|off`` specifies the use of the abstract socket namespace, 3382 rather than the filesystem. Optional, defaults to false. 3383 ``tight=on|off`` sets the socket length of abstract sockets to their minimum, 3384 rather than the full sun_path length. Optional, defaults to true. 3385 3386``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]`` 3387 Sends all traffic from the guest to a remote host over UDP. 3388 3389 ``host`` specifies the remote host to connect to. If not specified 3390 it defaults to ``localhost``. 3391 3392 ``port`` specifies the port on the remote host to connect to. 3393 ``port`` is required. 3394 3395 ``localaddr`` specifies the local address to bind to. If not 3396 specified it defaults to ``0.0.0.0``. 3397 3398 ``localport`` specifies the local port to bind to. If not specified 3399 any available local port will be used. 3400 3401 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used. 3402 If neither is specified the device may use either protocol. 3403 3404``-chardev msmouse,id=id`` 3405 Forward QEMU's emulated msmouse events to the guest. ``msmouse`` 3406 does not take any options. 3407 3408``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]`` 3409 Connect to a QEMU text console. ``vc`` may optionally be given a 3410 specific size. 3411 3412 ``width`` and ``height`` specify the width and height respectively 3413 of the console, in pixels. 3414 3415 ``cols`` and ``rows`` specify that the console be sized to fit a 3416 text console with the given dimensions. 3417 3418``-chardev ringbuf,id=id[,size=size]`` 3419 Create a ring buffer with fixed size ``size``. size must be a power 3420 of two and defaults to ``64K``. 3421 3422``-chardev file,id=id,path=path`` 3423 Log all traffic received from the guest to a file. 3424 3425 ``path`` specifies the path of the file to be opened. This file will 3426 be created if it does not already exist, and overwritten if it does. 3427 ``path`` is required. 3428 3429``-chardev pipe,id=id,path=path`` 3430 Create a two-way connection to the guest. The behaviour differs 3431 slightly between Windows hosts and other hosts: 3432 3433 On Windows, a single duplex pipe will be created at 3434 ``\\.pipe\path``. 3435 3436 On other hosts, 2 pipes will be created called ``path.in`` and 3437 ``path.out``. Data written to ``path.in`` will be received by the 3438 guest. Data written by the guest can be read from ``path.out``. QEMU 3439 will not create these fifos, and requires them to be present. 3440 3441 ``path`` forms part of the pipe path as described above. ``path`` is 3442 required. 3443 3444``-chardev console,id=id`` 3445 Send traffic from the guest to QEMU's standard output. ``console`` 3446 does not take any options. 3447 3448 ``console`` is only available on Windows hosts. 3449 3450``-chardev serial,id=id,path=path`` 3451 Send traffic from the guest to a serial device on the host. 3452 3453 On Unix hosts serial will actually accept any tty device, not only 3454 serial lines. 3455 3456 ``path`` specifies the name of the serial device to open. 3457 3458``-chardev pty,id=id`` 3459 Create a new pseudo-terminal on the host and connect to it. ``pty`` 3460 does not take any options. 3461 3462 ``pty`` is not available on Windows hosts. 3463 3464``-chardev stdio,id=id[,signal=on|off]`` 3465 Connect to standard input and standard output of the QEMU process. 3466 3467 ``signal`` controls if signals are enabled on the terminal, that 3468 includes exiting QEMU with the key sequence Control-c. This option 3469 is enabled by default, use ``signal=off`` to disable it. 3470 3471``-chardev braille,id=id`` 3472 Connect to a local BrlAPI server. ``braille`` does not take any 3473 options. 3474 3475``-chardev tty,id=id,path=path`` 3476 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD 3477 and DragonFlyBSD hosts. It is an alias for ``serial``. 3478 3479 ``path`` specifies the path to the tty. ``path`` is required. 3480 3481``-chardev parallel,id=id,path=path`` 3482 \ 3483``-chardev parport,id=id,path=path`` 3484 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD 3485 hosts. 3486 3487 Connect to a local parallel port. 3488 3489 ``path`` specifies the path to the parallel port device. ``path`` is 3490 required. 3491 3492``-chardev spicevmc,id=id,debug=debug,name=name`` 3493 ``spicevmc`` is only available when spice support is built in. 3494 3495 ``debug`` debug level for spicevmc 3496 3497 ``name`` name of spice channel to connect to 3498 3499 Connect to a spice virtual machine channel, such as vdiport. 3500 3501``-chardev spiceport,id=id,debug=debug,name=name`` 3502 ``spiceport`` is only available when spice support is built in. 3503 3504 ``debug`` debug level for spicevmc 3505 3506 ``name`` name of spice port to connect to 3507 3508 Connect to a spice port, allowing a Spice client to handle the 3509 traffic identified by a name (preferably a fqdn). 3510ERST 3511 3512DEFHEADING() 3513 3514#ifdef CONFIG_TPM 3515DEFHEADING(TPM device options:) 3516 3517DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \ 3518 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n" 3519 " use path to provide path to a character device; default is /dev/tpm0\n" 3520 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n" 3521 " not provided it will be searched for in /sys/class/misc/tpm?/device\n" 3522 "-tpmdev emulator,id=id,chardev=dev\n" 3523 " configure the TPM device using chardev backend\n", 3524 QEMU_ARCH_ALL) 3525SRST 3526The general form of a TPM device option is: 3527 3528``-tpmdev backend,id=id[,options]`` 3529 The specific backend type will determine the applicable options. The 3530 ``-tpmdev`` option creates the TPM backend and requires a 3531 ``-device`` option that specifies the TPM frontend interface model. 3532 3533 Use ``-tpmdev help`` to print all available TPM backend types. 3534 3535The available backends are: 3536 3537``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path`` 3538 (Linux-host only) Enable access to the host's TPM using the 3539 passthrough driver. 3540 3541 ``path`` specifies the path to the host's TPM device, i.e., on a 3542 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by 3543 default ``/dev/tpm0`` is used. 3544 3545 ``cancel-path`` specifies the path to the host TPM device's sysfs 3546 entry allowing for cancellation of an ongoing TPM command. 3547 ``cancel-path`` is optional and by default QEMU will search for the 3548 sysfs entry to use. 3549 3550 Some notes about using the host's TPM with the passthrough driver: 3551 3552 The TPM device accessed by the passthrough driver must not be used 3553 by any other application on the host. 3554 3555 Since the host's firmware (BIOS/UEFI) has already initialized the 3556 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize 3557 the TPM again and may therefore not show a TPM-specific menu that 3558 would otherwise allow the user to configure the TPM, e.g., allow the 3559 user to enable/disable or activate/deactivate the TPM. Further, if 3560 TPM ownership is released from within a VM then the host's TPM will 3561 get disabled and deactivated. To enable and activate the TPM again 3562 afterwards, the host has to be rebooted and the user is required to 3563 enter the firmware's menu to enable and activate the TPM. If the TPM 3564 is left disabled and/or deactivated most TPM commands will fail. 3565 3566 To create a passthrough TPM use the following two options: 3567 3568 :: 3569 3570 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0 3571 3572 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by 3573 ``tpmdev=tpm0`` in the device option. 3574 3575``-tpmdev emulator,id=id,chardev=dev`` 3576 (Linux-host only) Enable access to a TPM emulator using Unix domain 3577 socket based chardev backend. 3578 3579 ``chardev`` specifies the unique ID of a character device backend 3580 that provides connection to the software TPM server. 3581 3582 To create a TPM emulator backend device with chardev socket backend: 3583 3584 :: 3585 3586 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0 3587ERST 3588 3589DEFHEADING() 3590 3591#endif 3592 3593DEFHEADING(Linux/Multiboot boot specific:) 3594SRST 3595When using these options, you can use a given Linux or Multiboot kernel 3596without installing it in the disk image. It can be useful for easier 3597testing of various kernels. 3598 3599 3600ERST 3601 3602DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \ 3603 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL) 3604SRST 3605``-kernel bzImage`` 3606 Use bzImage as kernel image. The kernel can be either a Linux kernel 3607 or in multiboot format. 3608ERST 3609 3610DEF("append", HAS_ARG, QEMU_OPTION_append, \ 3611 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL) 3612SRST 3613``-append cmdline`` 3614 Use cmdline as kernel command line 3615ERST 3616 3617DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \ 3618 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL) 3619SRST 3620``-initrd file`` 3621 Use file as initial ram disk. 3622 3623``-initrd "file1 arg=foo,file2"`` 3624 This syntax is only available with multiboot. 3625 3626 Use file1 and file2 as modules and pass arg=foo as parameter to the 3627 first module. 3628ERST 3629 3630DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \ 3631 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL) 3632SRST 3633``-dtb file`` 3634 Use file as a device tree binary (dtb) image and pass it to the 3635 kernel on boot. 3636ERST 3637 3638DEFHEADING() 3639 3640DEFHEADING(Debug/Expert options:) 3641 3642DEF("compat", HAS_ARG, QEMU_OPTION_compat, 3643 "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n" 3644 " Policy for handling deprecated management interfaces\n", 3645 QEMU_ARCH_ALL) 3646SRST 3647``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]`` 3648 Set policy for handling deprecated management interfaces (experimental): 3649 3650 ``deprecated-input=accept`` (default) 3651 Accept deprecated commands and arguments 3652 ``deprecated-input=reject`` 3653 Reject deprecated commands and arguments 3654 ``deprecated-input=crash`` 3655 Crash on deprecated commands and arguments 3656 ``deprecated-output=accept`` (default) 3657 Emit deprecated command results and events 3658 ``deprecated-output=hide`` 3659 Suppress deprecated command results and events 3660 3661 Limitation: covers only syntactic aspects of QMP. 3662ERST 3663 3664DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg, 3665 "-fw_cfg [name=]<name>,file=<file>\n" 3666 " add named fw_cfg entry with contents from file\n" 3667 "-fw_cfg [name=]<name>,string=<str>\n" 3668 " add named fw_cfg entry with contents from string\n", 3669 QEMU_ARCH_ALL) 3670SRST 3671``-fw_cfg [name=]name,file=file`` 3672 Add named fw\_cfg entry with contents from file file. 3673 3674``-fw_cfg [name=]name,string=str`` 3675 Add named fw\_cfg entry with contents from string str. 3676 3677 The terminating NUL character of the contents of str will not be 3678 included as part of the fw\_cfg item data. To insert contents with 3679 embedded NUL characters, you have to use the file parameter. 3680 3681 The fw\_cfg entries are passed by QEMU through to the guest. 3682 3683 Example: 3684 3685 :: 3686 3687 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin 3688 3689 creates an fw\_cfg entry named opt/com.mycompany/blob with contents 3690 from ./my\_blob.bin. 3691ERST 3692 3693DEF("serial", HAS_ARG, QEMU_OPTION_serial, \ 3694 "-serial dev redirect the serial port to char device 'dev'\n", 3695 QEMU_ARCH_ALL) 3696SRST 3697``-serial dev`` 3698 Redirect the virtual serial port to host character device dev. The 3699 default device is ``vc`` in graphical mode and ``stdio`` in non 3700 graphical mode. 3701 3702 This option can be used several times to simulate up to 4 serial 3703 ports. 3704 3705 Use ``-serial none`` to disable all serial ports. 3706 3707 Available character devices are: 3708 3709 ``vc[:WxH]`` 3710 Virtual console. Optionally, a width and height can be given in 3711 pixel with 3712 3713 :: 3714 3715 vc:800x600 3716 3717 It is also possible to specify width or height in characters: 3718 3719 :: 3720 3721 vc:80Cx24C 3722 3723 ``pty`` 3724 [Linux only] Pseudo TTY (a new PTY is automatically allocated) 3725 3726 ``none`` 3727 No device is allocated. 3728 3729 ``null`` 3730 void device 3731 3732 ``chardev:id`` 3733 Use a named character device defined with the ``-chardev`` 3734 option. 3735 3736 ``/dev/XXX`` 3737 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial 3738 port parameters are set according to the emulated ones. 3739 3740 ``/dev/parportN`` 3741 [Linux only, parallel port only] Use host parallel port N. 3742 Currently SPP and EPP parallel port features can be used. 3743 3744 ``file:filename`` 3745 Write output to filename. No character can be read. 3746 3747 ``stdio`` 3748 [Unix only] standard input/output 3749 3750 ``pipe:filename`` 3751 name pipe filename 3752 3753 ``COMn`` 3754 [Windows only] Use host serial port n 3755 3756 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]`` 3757 This implements UDP Net Console. When remote\_host or src\_ip 3758 are not specified they default to ``0.0.0.0``. When not using a 3759 specified src\_port a random port is automatically chosen. 3760 3761 If you just want a simple readonly console you can use 3762 ``netcat`` or ``nc``, by starting QEMU with: 3763 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time 3764 QEMU writes something to that port it will appear in the 3765 netconsole session. 3766 3767 If you plan to send characters back via netconsole or you want 3768 to stop and start QEMU a lot of times, you should have QEMU use 3769 the same source port each time by using something like ``-serial 3770 udp::4555@:4556`` to QEMU. Another approach is to use a patched 3771 version of netcat which can listen to a TCP port and send and 3772 receive characters via udp. If you have a patched version of 3773 netcat which activates telnet remote echo and single char 3774 transfer, then you can use the following options to set up a 3775 netcat redirector to allow telnet on port 5555 to access the 3776 QEMU port. 3777 3778 ``QEMU Options:`` 3779 -serial udp::4555@:4556 3780 3781 ``netcat options:`` 3782 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T 3783 3784 ``telnet options:`` 3785 localhost 5555 3786 3787 ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]`` 3788 The TCP Net Console has two modes of operation. It can send the 3789 serial I/O to a location or wait for a connection from a 3790 location. By default the TCP Net Console is sent to host at the 3791 port. If you use the ``server=on`` option QEMU will wait for a client 3792 socket application to connect to the port before continuing, 3793 unless the ``wait=on|off`` option was specified. The ``nodelay=on|off`` 3794 option disables the Nagle buffering algorithm. The ``reconnect=on`` 3795 option only applies if ``server=no`` is set, if the connection goes 3796 down it will attempt to reconnect at the given interval. If host 3797 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a 3798 time is accepted. You can use ``telnet=on`` to connect to the 3799 corresponding character device. 3800 3801 ``Example to send tcp console to 192.168.0.2 port 4444`` 3802 -serial tcp:192.168.0.2:4444 3803 3804 ``Example to listen and wait on port 4444 for connection`` 3805 -serial tcp::4444,server=on 3806 3807 ``Example to not wait and listen on ip 192.168.0.100 port 4444`` 3808 -serial tcp:192.168.0.100:4444,server=on,wait=off 3809 3810 ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]`` 3811 The telnet protocol is used instead of raw tcp sockets. The 3812 options work the same as if you had specified ``-serial tcp``. 3813 The difference is that the port acts like a telnet server or 3814 client using telnet option negotiation. This will also allow you 3815 to send the MAGIC\_SYSRQ sequence if you use a telnet that 3816 supports sending the break sequence. Typically in unix telnet 3817 you do it with Control-] and then type "send break" followed by 3818 pressing the enter key. 3819 3820 ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]`` 3821 The WebSocket protocol is used instead of raw tcp socket. The 3822 port acts as a WebSocket server. Client mode is not supported. 3823 3824 ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]`` 3825 A unix domain socket is used instead of a tcp socket. The option 3826 works the same as if you had specified ``-serial tcp`` except 3827 the unix domain socket path is used for connections. 3828 3829 ``mon:dev_string`` 3830 This is a special option to allow the monitor to be multiplexed 3831 onto another serial port. The monitor is accessed with key 3832 sequence of Control-a and then pressing c. dev\_string should be 3833 any one of the serial devices specified above. An example to 3834 multiplex the monitor onto a telnet server listening on port 3835 4444 would be: 3836 3837 ``-serial mon:telnet::4444,server=on,wait=off`` 3838 3839 When the monitor is multiplexed to stdio in this way, Ctrl+C 3840 will not terminate QEMU any more but will be passed to the guest 3841 instead. 3842 3843 ``braille`` 3844 Braille device. This will use BrlAPI to display the braille 3845 output on a real or fake device. 3846 3847 ``msmouse`` 3848 Three button serial mouse. Configure the guest to use Microsoft 3849 protocol. 3850ERST 3851 3852DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \ 3853 "-parallel dev redirect the parallel port to char device 'dev'\n", 3854 QEMU_ARCH_ALL) 3855SRST 3856``-parallel dev`` 3857 Redirect the virtual parallel port to host device dev (same devices 3858 as the serial port). On Linux hosts, ``/dev/parportN`` can be used 3859 to use hardware devices connected on the corresponding host parallel 3860 port. 3861 3862 This option can be used several times to simulate up to 3 parallel 3863 ports. 3864 3865 Use ``-parallel none`` to disable all parallel ports. 3866ERST 3867 3868DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \ 3869 "-monitor dev redirect the monitor to char device 'dev'\n", 3870 QEMU_ARCH_ALL) 3871SRST 3872``-monitor dev`` 3873 Redirect the monitor to host device dev (same devices as the serial 3874 port). The default device is ``vc`` in graphical mode and ``stdio`` 3875 in non graphical mode. Use ``-monitor none`` to disable the default 3876 monitor. 3877ERST 3878DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \ 3879 "-qmp dev like -monitor but opens in 'control' mode\n", 3880 QEMU_ARCH_ALL) 3881SRST 3882``-qmp dev`` 3883 Like -monitor but opens in 'control' mode. 3884ERST 3885DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \ 3886 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n", 3887 QEMU_ARCH_ALL) 3888SRST 3889``-qmp-pretty dev`` 3890 Like -qmp but uses pretty JSON formatting. 3891ERST 3892 3893DEF("mon", HAS_ARG, QEMU_OPTION_mon, \ 3894 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL) 3895SRST 3896``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]`` 3897 Setup monitor on chardev name. ``mode=control`` configures 3898 a QMP monitor (a JSON RPC-style protocol) and it is not the 3899 same as HMP, the human monitor that has a "(qemu)" prompt. 3900 ``pretty`` is only valid when ``mode=control``, 3901 turning on JSON pretty printing to ease 3902 human reading and debugging. 3903ERST 3904 3905DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \ 3906 "-debugcon dev redirect the debug console to char device 'dev'\n", 3907 QEMU_ARCH_ALL) 3908SRST 3909``-debugcon dev`` 3910 Redirect the debug console to host device dev (same devices as the 3911 serial port). The debug console is an I/O port which is typically 3912 port 0xe9; writing to that I/O port sends output to this device. The 3913 default device is ``vc`` in graphical mode and ``stdio`` in non 3914 graphical mode. 3915ERST 3916 3917DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \ 3918 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL) 3919SRST 3920``-pidfile file`` 3921 Store the QEMU process PID in file. It is useful if you launch QEMU 3922 from a script. 3923ERST 3924 3925DEF("singlestep", 0, QEMU_OPTION_singlestep, \ 3926 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL) 3927SRST 3928``-singlestep`` 3929 Run the emulation in single step mode. 3930ERST 3931 3932DEF("preconfig", 0, QEMU_OPTION_preconfig, \ 3933 "--preconfig pause QEMU before machine is initialized (experimental)\n", 3934 QEMU_ARCH_ALL) 3935SRST 3936``--preconfig`` 3937 Pause QEMU for interactive configuration before the machine is 3938 created, which allows querying and configuring properties that will 3939 affect machine initialization. Use QMP command 'x-exit-preconfig' to 3940 exit the preconfig state and move to the next state (i.e. run guest 3941 if -S isn't used or pause the second time if -S is used). This 3942 option is experimental. 3943ERST 3944 3945DEF("S", 0, QEMU_OPTION_S, \ 3946 "-S freeze CPU at startup (use 'c' to start execution)\n", 3947 QEMU_ARCH_ALL) 3948SRST 3949``-S`` 3950 Do not start CPU at startup (you must type 'c' in the monitor). 3951ERST 3952 3953DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit, 3954 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n" 3955 " run qemu with overcommit hints\n" 3956 " mem-lock=on|off controls memory lock support (default: off)\n" 3957 " cpu-pm=on|off controls cpu power management (default: off)\n", 3958 QEMU_ARCH_ALL) 3959SRST 3960``-overcommit mem-lock=on|off`` 3961 \ 3962``-overcommit cpu-pm=on|off`` 3963 Run qemu with hints about host resource overcommit. The default is 3964 to assume that host overcommits all resources. 3965 3966 Locking qemu and guest memory can be enabled via ``mem-lock=on`` 3967 (disabled by default). This works when host memory is not 3968 overcommitted and reduces the worst-case latency for guest. 3969 3970 Guest ability to manage power state of host cpus (increasing latency 3971 for other processes on the same host cpu, but decreasing latency for 3972 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This 3973 works best when host CPU is not overcommitted. When used, host 3974 estimates of CPU cycle and power utilization will be incorrect, not 3975 taking into account guest idle time. 3976ERST 3977 3978DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \ 3979 "-gdb dev accept gdb connection on 'dev'. (QEMU defaults to starting\n" 3980 " the guest without waiting for gdb to connect; use -S too\n" 3981 " if you want it to not start execution.)\n", 3982 QEMU_ARCH_ALL) 3983SRST 3984``-gdb dev`` 3985 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter 3986 in the System Emulation Users Guide). Note that this option does not pause QEMU 3987 execution -- if you want QEMU to not start the guest until you 3988 connect with gdb and issue a ``continue`` command, you will need to 3989 also pass the ``-S`` option to QEMU. 3990 3991 The most usual configuration is to listen on a local TCP socket:: 3992 3993 -gdb tcp::3117 3994 3995 but you can specify other backends; UDP, pseudo TTY, or even stdio 3996 are all reasonable use cases. For example, a stdio connection 3997 allows you to start QEMU from within gdb and establish the 3998 connection via a pipe: 3999 4000 .. parsed-literal:: 4001 4002 (gdb) target remote | exec |qemu_system| -gdb stdio ... 4003ERST 4004 4005DEF("s", 0, QEMU_OPTION_s, \ 4006 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n", 4007 QEMU_ARCH_ALL) 4008SRST 4009``-s`` 4010 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234 4011 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide). 4012ERST 4013 4014DEF("d", HAS_ARG, QEMU_OPTION_d, \ 4015 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n", 4016 QEMU_ARCH_ALL) 4017SRST 4018``-d item1[,...]`` 4019 Enable logging of specified items. Use '-d help' for a list of log 4020 items. 4021ERST 4022 4023DEF("D", HAS_ARG, QEMU_OPTION_D, \ 4024 "-D logfile output log to logfile (default stderr)\n", 4025 QEMU_ARCH_ALL) 4026SRST 4027``-D logfile`` 4028 Output log in logfile instead of to stderr 4029ERST 4030 4031DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \ 4032 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n", 4033 QEMU_ARCH_ALL) 4034SRST 4035``-dfilter range1[,...]`` 4036 Filter debug output to that relevant to a range of target addresses. 4037 The filter spec can be either start+size, start-size or start..end 4038 where start end and size are the addresses and sizes required. For 4039 example: 4040 4041 :: 4042 4043 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000 4044 4045 Will dump output for any code in the 0x1000 sized block starting at 4046 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and 4047 another 0x1000 sized block starting at 0xffffffc00005f000. 4048ERST 4049 4050DEF("seed", HAS_ARG, QEMU_OPTION_seed, \ 4051 "-seed number seed the pseudo-random number generator\n", 4052 QEMU_ARCH_ALL) 4053SRST 4054``-seed number`` 4055 Force the guest to use a deterministic pseudo-random number 4056 generator, seeded with number. This does not affect crypto routines 4057 within the host. 4058ERST 4059 4060DEF("L", HAS_ARG, QEMU_OPTION_L, \ 4061 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n", 4062 QEMU_ARCH_ALL) 4063SRST 4064``-L path`` 4065 Set the directory for the BIOS, VGA BIOS and keymaps. 4066 4067 To list all the data directories, use ``-L help``. 4068ERST 4069 4070DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ 4071 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) 4072SRST 4073``-bios file`` 4074 Set the filename for the BIOS. 4075ERST 4076 4077DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ 4078 "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ALL) 4079SRST 4080``-enable-kvm`` 4081 Enable KVM full virtualization support. This option is only 4082 available if KVM support is enabled when compiling. 4083ERST 4084 4085DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid, 4086 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL) 4087DEF("xen-attach", 0, QEMU_OPTION_xen_attach, 4088 "-xen-attach attach to existing xen domain\n" 4089 " libxl will use this when starting QEMU\n", 4090 QEMU_ARCH_ALL) 4091DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict, 4092 "-xen-domid-restrict restrict set of available xen operations\n" 4093 " to specified domain id. (Does not affect\n" 4094 " xenpv machine type).\n", 4095 QEMU_ARCH_ALL) 4096SRST 4097``-xen-domid id`` 4098 Specify xen guest domain id (XEN only). 4099 4100``-xen-attach`` 4101 Attach to existing xen domain. libxl will use this when starting 4102 QEMU (XEN only). Restrict set of available xen operations to 4103 specified domain id (XEN only). 4104ERST 4105 4106DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \ 4107 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL) 4108SRST 4109``-no-reboot`` 4110 Exit instead of rebooting. 4111ERST 4112 4113DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \ 4114 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL) 4115SRST 4116``-no-shutdown`` 4117 Don't exit QEMU on guest shutdown, but instead only stop the 4118 emulation. This allows for instance switching to monitor to commit 4119 changes to the disk image. 4120ERST 4121 4122DEF("action", HAS_ARG, QEMU_OPTION_action, 4123 "-action reboot=reset|shutdown\n" 4124 " action when guest reboots [default=reset]\n" 4125 "-action shutdown=poweroff|pause\n" 4126 " action when guest shuts down [default=poweroff]\n" 4127 "-action panic=pause|shutdown|none\n" 4128 " action when guest panics [default=shutdown]\n" 4129 "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" 4130 " action when watchdog fires [default=reset]\n", 4131 QEMU_ARCH_ALL) 4132SRST 4133``-action event=action`` 4134 The action parameter serves to modify QEMU's default behavior when 4135 certain guest events occur. It provides a generic method for specifying the 4136 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown`` 4137 parameters. 4138 4139 Examples: 4140 4141 ``-action panic=none`` 4142 ``-action reboot=shutdown,shutdown=pause`` 4143 ``-watchdog i6300esb -action watchdog=pause`` 4144 4145ERST 4146 4147DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \ 4148 "-loadvm [tag|id]\n" \ 4149 " start right away with a saved state (loadvm in monitor)\n", 4150 QEMU_ARCH_ALL) 4151SRST 4152``-loadvm file`` 4153 Start right away with a saved state (``loadvm`` in monitor) 4154ERST 4155 4156#ifndef _WIN32 4157DEF("daemonize", 0, QEMU_OPTION_daemonize, \ 4158 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL) 4159#endif 4160SRST 4161``-daemonize`` 4162 Daemonize the QEMU process after initialization. QEMU will not 4163 detach from standard IO until it is ready to receive connections on 4164 any of its devices. This option is a useful way for external 4165 programs to launch QEMU without having to cope with initialization 4166 race conditions. 4167ERST 4168 4169DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \ 4170 "-option-rom rom load a file, rom, into the option ROM space\n", 4171 QEMU_ARCH_ALL) 4172SRST 4173``-option-rom file`` 4174 Load the contents of file as an option ROM. This option is useful to 4175 load things like EtherBoot. 4176ERST 4177 4178DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \ 4179 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \ 4180 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n", 4181 QEMU_ARCH_ALL) 4182 4183SRST 4184``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]`` 4185 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at 4186 the current UTC or local time, respectively. ``localtime`` is 4187 required for correct date in MS-DOS or Windows. To start at a 4188 specific point in time, provide datetime in the format 4189 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC. 4190 4191 By default the RTC is driven by the host system time. This allows 4192 using of the RTC as accurate reference clock inside the guest, 4193 specifically if the host time is smoothly following an accurate 4194 external reference clock, e.g. via NTP. If you want to isolate the 4195 guest time from the host, you can set ``clock`` to ``rt`` instead, 4196 which provides a host monotonic clock if host support it. To even 4197 prevent the RTC from progressing during suspension, you can set 4198 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is 4199 recommended especially in icount mode in order to preserve 4200 determinism; however, note that in icount mode the speed of the 4201 virtual clock is variable and can in general differ from the host 4202 clock. 4203 4204 Enable ``driftfix`` (i386 targets only) if you experience time drift 4205 problems, specifically with Windows' ACPI HAL. This option will try 4206 to figure out how many timer interrupts were not processed by the 4207 Windows guest and will re-inject them. 4208ERST 4209 4210DEF("icount", HAS_ARG, QEMU_OPTION_icount, \ 4211 "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \ 4212 " enable virtual instruction counter with 2^N clock ticks per\n" \ 4213 " instruction, enable aligning the host and virtual clocks\n" \ 4214 " or disable real time cpu sleeping, and optionally enable\n" \ 4215 " record-and-replay mode\n", QEMU_ARCH_ALL) 4216SRST 4217``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]`` 4218 Enable virtual instruction counter. The virtual cpu will execute one 4219 instruction every 2^N ns of virtual time. If ``auto`` is specified 4220 then the virtual cpu speed will be automatically adjusted to keep 4221 virtual time within a few seconds of real time. 4222 4223 Note that while this option can give deterministic behavior, it does 4224 not provide cycle accurate emulation. Modern CPUs contain 4225 superscalar out of order cores with complex cache hierarchies. The 4226 number of instructions executed often has little or no correlation 4227 with actual performance. 4228 4229 When the virtual cpu is sleeping, the virtual time will advance at 4230 default speed unless ``sleep=on`` is specified. With 4231 ``sleep=on``, the virtual time will jump to the next timer 4232 deadline instantly whenever the virtual cpu goes to sleep mode and 4233 will not advance if no timer is enabled. This behavior gives 4234 deterministic execution times from the guest point of view. 4235 The default if icount is enabled is ``sleep=off``. 4236 ``sleep=on`` cannot be used together with either ``shift=auto`` 4237 or ``align=on``. 4238 4239 ``align=on`` will activate the delay algorithm which will try to 4240 synchronise the host clock and the virtual clock. The goal is to 4241 have a guest running at the real frequency imposed by the shift 4242 option. Whenever the guest clock is behind the host clock and if 4243 ``align=on`` is specified then we print a message to the user to 4244 inform about the delay. Currently this option does not work when 4245 ``shift`` is ``auto``. Note: The sync algorithm will work for those 4246 shift values for which the guest clock runs ahead of the host clock. 4247 Typically this happens when the shift value is high (how high 4248 depends on the host machine). The default if icount is enabled 4249 is ``align=off``. 4250 4251 When the ``rr`` option is specified deterministic record/replay is 4252 enabled. The ``rrfile=`` option must also be provided to 4253 specify the path to the replay log. In record mode data is written 4254 to this file, and in replay mode it is read back. 4255 If the ``rrsnapshot`` option is given then it specifies a VM snapshot 4256 name. In record mode, a new VM snapshot with the given name is created 4257 at the start of execution recording. In replay mode this option 4258 specifies the snapshot name used to load the initial VM state. 4259ERST 4260 4261DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \ 4262 "-watchdog model\n" \ 4263 " enable virtual hardware watchdog [default=none]\n", 4264 QEMU_ARCH_ALL) 4265SRST 4266``-watchdog model`` 4267 Create a virtual hardware watchdog device. Once enabled (by a guest 4268 action), the watchdog must be periodically polled by an agent inside 4269 the guest or else the guest will be restarted. Choose a model for 4270 which your guest has drivers. 4271 4272 The model is the model of hardware watchdog to emulate. Use 4273 ``-watchdog help`` to list available hardware models. Only one 4274 watchdog can be enabled for a guest. 4275 4276 The following models may be available: 4277 4278 ``ib700`` 4279 iBASE 700 is a very simple ISA watchdog with a single timer. 4280 4281 ``i6300esb`` 4282 Intel 6300ESB I/O controller hub is a much more featureful 4283 PCI-based dual-timer watchdog. 4284 4285 ``diag288`` 4286 A virtual watchdog for s390x backed by the diagnose 288 4287 hypercall (currently KVM only). 4288ERST 4289 4290DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \ 4291 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \ 4292 " action when watchdog fires [default=reset]\n", 4293 QEMU_ARCH_ALL) 4294SRST 4295``-watchdog-action action`` 4296 The action controls what QEMU will do when the watchdog timer 4297 expires. The default is ``reset`` (forcefully reset the guest). 4298 Other possible actions are: ``shutdown`` (attempt to gracefully 4299 shutdown the guest), ``poweroff`` (forcefully poweroff the guest), 4300 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the 4301 guest), ``debug`` (print a debug message and continue), or ``none`` 4302 (do nothing). 4303 4304 Note that the ``shutdown`` action requires that the guest responds 4305 to ACPI signals, which it may not be able to do in the sort of 4306 situations where the watchdog would have expired, and thus 4307 ``-watchdog-action shutdown`` is not recommended for production use. 4308 4309 Examples: 4310 4311 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700`` 4312 4313ERST 4314 4315DEF("echr", HAS_ARG, QEMU_OPTION_echr, \ 4316 "-echr chr set terminal escape character instead of ctrl-a\n", 4317 QEMU_ARCH_ALL) 4318SRST 4319``-echr numeric_ascii_value`` 4320 Change the escape character used for switching to the monitor when 4321 using monitor and serial sharing. The default is ``0x01`` when using 4322 the ``-nographic`` option. ``0x01`` is equal to pressing 4323 ``Control-a``. You can select a different character from the ascii 4324 control keys where 1 through 26 map to Control-a through Control-z. 4325 For instance you could use the either of the following to change the 4326 escape character to Control-t. 4327 4328 ``-echr 0x14``; \ ``-echr 20`` 4329 4330ERST 4331 4332DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \ 4333 "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \ 4334 "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \ 4335 "-incoming unix:socketpath\n" \ 4336 " prepare for incoming migration, listen on\n" \ 4337 " specified protocol and socket address\n" \ 4338 "-incoming fd:fd\n" \ 4339 "-incoming exec:cmdline\n" \ 4340 " accept incoming migration on given file descriptor\n" \ 4341 " or from given external command\n" \ 4342 "-incoming defer\n" \ 4343 " wait for the URI to be specified via migrate_incoming\n", 4344 QEMU_ARCH_ALL) 4345SRST 4346``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]`` 4347 \ 4348``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]`` 4349 Prepare for incoming migration, listen on a given tcp port. 4350 4351``-incoming unix:socketpath`` 4352 Prepare for incoming migration, listen on a given unix socket. 4353 4354``-incoming fd:fd`` 4355 Accept incoming migration from a given filedescriptor. 4356 4357``-incoming exec:cmdline`` 4358 Accept incoming migration as an output from specified external 4359 command. 4360 4361``-incoming defer`` 4362 Wait for the URI to be specified via migrate\_incoming. The monitor 4363 can be used to change settings (such as migration parameters) prior 4364 to issuing the migrate\_incoming to allow the migration to begin. 4365ERST 4366 4367DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \ 4368 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL) 4369SRST 4370``-only-migratable`` 4371 Only allow migratable devices. Devices will not be allowed to enter 4372 an unmigratable state. 4373ERST 4374 4375DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \ 4376 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL) 4377SRST 4378``-nodefaults`` 4379 Don't create default devices. Normally, QEMU sets the default 4380 devices like serial port, parallel port, virtual console, monitor 4381 device, VGA adapter, floppy and CD-ROM drive and others. The 4382 ``-nodefaults`` option will disable all those default devices. 4383ERST 4384 4385#ifndef _WIN32 4386DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \ 4387 "-chroot dir chroot to dir just before starting the VM\n", 4388 QEMU_ARCH_ALL) 4389#endif 4390SRST 4391``-chroot dir`` 4392 Immediately before starting guest execution, chroot to the specified 4393 directory. Especially useful in combination with -runas. 4394ERST 4395 4396#ifndef _WIN32 4397DEF("runas", HAS_ARG, QEMU_OPTION_runas, \ 4398 "-runas user change to user id user just before starting the VM\n" \ 4399 " user can be numeric uid:gid instead\n", 4400 QEMU_ARCH_ALL) 4401#endif 4402SRST 4403``-runas user`` 4404 Immediately before starting guest execution, drop root privileges, 4405 switching to the specified user. 4406ERST 4407 4408DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env, 4409 "-prom-env variable=value\n" 4410 " set OpenBIOS nvram variables\n", 4411 QEMU_ARCH_PPC | QEMU_ARCH_SPARC) 4412SRST 4413``-prom-env variable=value`` 4414 Set OpenBIOS nvram variable to given value (PPC, SPARC only). 4415 4416 :: 4417 4418 qemu-system-sparc -prom-env 'auto-boot?=false' \ 4419 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single' 4420 4421 :: 4422 4423 qemu-system-ppc -prom-env 'auto-boot?=false' \ 4424 -prom-env 'boot-device=hd:2,\yaboot' \ 4425 -prom-env 'boot-args=conf=hd:2,\yaboot.conf' 4426ERST 4427DEF("semihosting", 0, QEMU_OPTION_semihosting, 4428 "-semihosting semihosting mode\n", 4429 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4430 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4431SRST 4432``-semihosting`` 4433 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only). 4434 4435 Note that this allows guest direct access to the host filesystem, so 4436 should only be used with a trusted guest OS. 4437 4438 See the -semihosting-config option documentation for further 4439 information about the facilities this enables. 4440ERST 4441DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, 4442 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \ 4443 " semihosting configuration\n", 4444QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4445QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4446SRST 4447``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]`` 4448 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V 4449 only). 4450 4451 Note that this allows guest direct access to the host filesystem, so 4452 should only be used with a trusted guest OS. 4453 4454 On Arm this implements the standard semihosting API, version 2.0. 4455 4456 On M68K this implements the "ColdFire GDB" interface used by 4457 libgloss. 4458 4459 Xtensa semihosting provides basic file IO calls, such as 4460 open/read/write/seek/select. Tensilica baremetal libc for ISS and 4461 linux platform "sim" use this interface. 4462 4463 On RISC-V this implements the standard semihosting API, version 0.2. 4464 4465 ``target=native|gdb|auto`` 4466 Defines where the semihosting calls will be addressed, to QEMU 4467 (``native``) or to GDB (``gdb``). The default is ``auto``, which 4468 means ``gdb`` during debug sessions and ``native`` otherwise. 4469 4470 ``chardev=str1`` 4471 Send the output to a chardev backend output for native or auto 4472 output when not in gdb 4473 4474 ``arg=str1,arg=str2,...`` 4475 Allows the user to pass input arguments, and can be used 4476 multiple times to build up a list. The old-style 4477 ``-kernel``/``-append`` method of passing a command line is 4478 still supported for backward compatibility. If both the 4479 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are 4480 specified, the former is passed to semihosting as it always 4481 takes precedence. 4482ERST 4483DEF("old-param", 0, QEMU_OPTION_old_param, 4484 "-old-param old param mode\n", QEMU_ARCH_ARM) 4485SRST 4486``-old-param`` 4487 Old param mode (ARM only). 4488ERST 4489 4490DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ 4491 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ 4492 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \ 4493 " Enable seccomp mode 2 system call filter (default 'off').\n" \ 4494 " use 'obsolete' to allow obsolete system calls that are provided\n" \ 4495 " by the kernel, but typically no longer used by modern\n" \ 4496 " C library implementations.\n" \ 4497 " use 'elevateprivileges' to allow or deny the QEMU process ability\n" \ 4498 " to elevate privileges using set*uid|gid system calls.\n" \ 4499 " The value 'children' will deny set*uid|gid system calls for\n" \ 4500 " main QEMU process but will allow forks and execves to run unprivileged\n" \ 4501 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \ 4502 " blocking *fork and execve\n" \ 4503 " use 'resourcecontrol' to disable process affinity and schedular priority\n", 4504 QEMU_ARCH_ALL) 4505SRST 4506``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]`` 4507 Enable Seccomp mode 2 system call filter. 'on' will enable syscall 4508 filtering and 'off' will disable it. The default is 'off'. 4509 4510 ``obsolete=string`` 4511 Enable Obsolete system calls 4512 4513 ``elevateprivileges=string`` 4514 Disable set\*uid\|gid system calls 4515 4516 ``spawn=string`` 4517 Disable \*fork and execve 4518 4519 ``resourcecontrol=string`` 4520 Disable process affinity and schedular priority 4521ERST 4522 4523DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig, 4524 "-readconfig <file>\n", QEMU_ARCH_ALL) 4525SRST 4526``-readconfig file`` 4527 Read device configuration from file. This approach is useful when 4528 you want to spawn QEMU process with many command line options but 4529 you don't want to exceed the command line character limit. 4530ERST 4531DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig, 4532 "-writeconfig <file>\n" 4533 " read/write config file (deprecated)\n", QEMU_ARCH_ALL) 4534SRST 4535ERST 4536 4537DEF("no-user-config", 0, QEMU_OPTION_nouserconfig, 4538 "-no-user-config\n" 4539 " do not load default user-provided config files at startup\n", 4540 QEMU_ARCH_ALL) 4541SRST 4542``-no-user-config`` 4543 The ``-no-user-config`` option makes QEMU not load any of the 4544 user-provided config files on sysconfdir. 4545ERST 4546 4547DEF("trace", HAS_ARG, QEMU_OPTION_trace, 4548 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n" 4549 " specify tracing options\n", 4550 QEMU_ARCH_ALL) 4551SRST 4552``-trace [[enable=]pattern][,events=file][,file=file]`` 4553 .. include:: ../qemu-option-trace.rst.inc 4554 4555ERST 4556DEF("plugin", HAS_ARG, QEMU_OPTION_plugin, 4557 "-plugin [file=]<file>[,<argname>=<argvalue>]\n" 4558 " load a plugin\n", 4559 QEMU_ARCH_ALL) 4560SRST 4561``-plugin file=file[,argname=argvalue]`` 4562 Load a plugin. 4563 4564 ``file=file`` 4565 Load the given plugin from a shared library file. 4566 4567 ``argname=argvalue`` 4568 Argument passed to the plugin. (Can be given multiple times.) 4569ERST 4570 4571HXCOMM Internal use 4572DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL) 4573DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL) 4574 4575#ifdef __linux__ 4576DEF("enable-fips", 0, QEMU_OPTION_enablefips, 4577 "-enable-fips enable FIPS 140-2 compliance\n", 4578 QEMU_ARCH_ALL) 4579#endif 4580SRST 4581``-enable-fips`` 4582 Enable FIPS 140-2 compliance mode. 4583ERST 4584 4585DEF("msg", HAS_ARG, QEMU_OPTION_msg, 4586 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n" 4587 " control error message format\n" 4588 " timestamp=on enables timestamps (default: off)\n" 4589 " guest-name=on enables guest name prefix but only if\n" 4590 " -name guest option is set (default: off)\n", 4591 QEMU_ARCH_ALL) 4592SRST 4593``-msg [timestamp[=on|off]][,guest-name[=on|off]]`` 4594 Control error message format. 4595 4596 ``timestamp=on|off`` 4597 Prefix messages with a timestamp. Default is off. 4598 4599 ``guest-name=on|off`` 4600 Prefix messages with guest name but only if -name guest option is set 4601 otherwise the option is ignored. Default is off. 4602ERST 4603 4604DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate, 4605 "-dump-vmstate <file>\n" 4606 " Output vmstate information in JSON format to file.\n" 4607 " Use the scripts/vmstate-static-checker.py file to\n" 4608 " check for possible regressions in migration code\n" 4609 " by comparing two such vmstate dumps.\n", 4610 QEMU_ARCH_ALL) 4611SRST 4612``-dump-vmstate file`` 4613 Dump json-encoded vmstate information for current machine type to 4614 file in file 4615ERST 4616 4617DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile, 4618 "-enable-sync-profile\n" 4619 " enable synchronization profiling\n", 4620 QEMU_ARCH_ALL) 4621SRST 4622``-enable-sync-profile`` 4623 Enable synchronization profiling. 4624ERST 4625 4626DEFHEADING() 4627 4628DEFHEADING(Generic object creation:) 4629 4630DEF("object", HAS_ARG, QEMU_OPTION_object, 4631 "-object TYPENAME[,PROP1=VALUE1,...]\n" 4632 " create a new object of type TYPENAME setting properties\n" 4633 " in the order they are specified. Note that the 'id'\n" 4634 " property must be set. These objects are placed in the\n" 4635 " '/objects' path.\n", 4636 QEMU_ARCH_ALL) 4637SRST 4638``-object typename[,prop1=value1,...]`` 4639 Create a new object of type typename setting properties in the order 4640 they are specified. Note that the 'id' property must be set. These 4641 objects are placed in the '/objects' path. 4642 4643 ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,readonly=on|off`` 4644 Creates a memory file backend object, which can be used to back 4645 the guest RAM with huge pages. 4646 4647 The ``id`` parameter is a unique ID that will be used to 4648 reference this memory region in other parameters, e.g. ``-numa``, 4649 ``-device nvdimm``, etc. 4650 4651 The ``size`` option provides the size of the memory region, and 4652 accepts common suffixes, e.g. ``500M``. 4653 4654 The ``mem-path`` provides the path to either a shared memory or 4655 huge page filesystem mount. 4656 4657 The ``share`` boolean option determines whether the memory 4658 region is marked as private to QEMU, or shared. The latter 4659 allows a co-operating external process to access the QEMU memory 4660 region. 4661 4662 The ``share`` is also required for pvrdma devices due to 4663 limitations in the RDMA API provided by Linux. 4664 4665 Setting share=on might affect the ability to configure NUMA 4666 bindings for the memory backend under some circumstances, see 4667 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel 4668 source tree for additional details. 4669 4670 Setting the ``discard-data`` boolean option to on indicates that 4671 file contents can be destroyed when QEMU exits, to avoid 4672 unnecessarily flushing data to the backing file. Note that 4673 ``discard-data`` is only an optimization, and QEMU might not 4674 discard file contents if it aborts unexpectedly or is terminated 4675 using SIGKILL. 4676 4677 The ``merge`` boolean option enables memory merge, also known as 4678 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider 4679 the pages for memory deduplication. 4680 4681 Setting the ``dump`` boolean option to off excludes the memory 4682 from core dumps. This feature is also known as MADV\_DONTDUMP. 4683 4684 The ``prealloc`` boolean option enables memory preallocation. 4685 4686 The ``host-nodes`` option binds the memory range to a list of 4687 NUMA host nodes. 4688 4689 The ``policy`` option sets the NUMA policy to one of the 4690 following values: 4691 4692 ``default`` 4693 default host policy 4694 4695 ``preferred`` 4696 prefer the given host node list for allocation 4697 4698 ``bind`` 4699 restrict memory allocation to the given host node list 4700 4701 ``interleave`` 4702 interleave memory allocations across the given host node 4703 list 4704 4705 The ``align`` option specifies the base address alignment when 4706 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg 4707 ``2M``. Some backend store specified by ``mem-path`` requires an 4708 alignment different than the default one used by QEMU, eg the 4709 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In 4710 such cases, users can specify the required alignment via this 4711 option. 4712 4713 The ``pmem`` option specifies whether the backing file specified 4714 by ``mem-path`` is in host persistent memory that can be 4715 accessed using the SNIA NVM programming model (e.g. Intel 4716 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary 4717 operations to guarantee the persistence of its own writes to 4718 ``mem-path`` (e.g. in vNVDIMM label emulation and live 4719 migration). Also, we will map the backend-file with MAP\_SYNC 4720 flag, which ensures the file metadata is in sync for 4721 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC 4722 requires support from both the host kernel (since Linux kernel 4723 4.15) and the filesystem of ``mem-path`` mounted with DAX 4724 option. 4725 4726 The ``readonly`` option specifies whether the backing file is opened 4727 read-only or read-write (default). 4728 4729 ``-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`` 4730 Creates a memory backend object, which can be used to back the 4731 guest RAM. Memory backend objects offer more control than the 4732 ``-m`` option that is traditionally used to define guest RAM. 4733 Please refer to ``memory-backend-file`` for a description of the 4734 options. 4735 4736 ``-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`` 4737 Creates an anonymous memory file backend object, which allows 4738 QEMU to share the memory with an external process (e.g. when 4739 using vhost-user). The memory is allocated with memfd and 4740 optional sealing. (Linux only) 4741 4742 The ``seal`` option creates a sealed-file, that will block 4743 further resizing the memory ('on' by default). 4744 4745 The ``hugetlb`` option specify the file to be created resides in 4746 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction 4747 with the ``hugetlb`` option, the ``hugetlbsize`` option specify 4748 the hugetlb page size on systems that support multiple hugetlb 4749 page sizes (it must be a power of 2 value supported by the 4750 system). 4751 4752 In some versions of Linux, the ``hugetlb`` option is 4753 incompatible with the ``seal`` option (requires at least Linux 4754 4.16). 4755 4756 Please refer to ``memory-backend-file`` for a description of the 4757 other options. 4758 4759 The ``share`` boolean option is on by default with memfd. 4760 4761 ``-object rng-builtin,id=id`` 4762 Creates a random number generator backend which obtains entropy 4763 from QEMU builtin functions. The ``id`` parameter is a unique ID 4764 that will be used to reference this entropy backend from the 4765 ``virtio-rng`` device. By default, the ``virtio-rng`` device 4766 uses this RNG backend. 4767 4768 ``-object rng-random,id=id,filename=/dev/random`` 4769 Creates a random number generator backend which obtains entropy 4770 from a device on the host. The ``id`` parameter is a unique ID 4771 that will be used to reference this entropy backend from the 4772 ``virtio-rng`` device. The ``filename`` parameter specifies 4773 which file to obtain entropy from and if omitted defaults to 4774 ``/dev/urandom``. 4775 4776 ``-object rng-egd,id=id,chardev=chardevid`` 4777 Creates a random number generator backend which obtains entropy 4778 from an external daemon running on the host. The ``id`` 4779 parameter is a unique ID that will be used to reference this 4780 entropy backend from the ``virtio-rng`` device. The ``chardev`` 4781 parameter is the unique ID of a character device backend that 4782 provides the connection to the RNG daemon. 4783 4784 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off`` 4785 Creates a TLS anonymous credentials object, which can be used to 4786 provide TLS support on network backends. The ``id`` parameter is 4787 a unique ID which network backends will use to access the 4788 credentials. The ``endpoint`` is either ``server`` or ``client`` 4789 depending on whether the QEMU network backend that uses the 4790 credentials will be acting as a client or as a server. If 4791 ``verify-peer`` is enabled (the default) then once the handshake 4792 is completed, the peer credentials will be verified, though this 4793 is a no-op for anonymous credentials. 4794 4795 The dir parameter tells QEMU where to find the credential files. 4796 For server endpoints, this directory may contain a file 4797 dh-params.pem providing diffie-hellman parameters to use for the 4798 TLS server. If the file is missing, QEMU will generate a set of 4799 DH parameters at startup. This is a computationally expensive 4800 operation that consumes random pool entropy, so it is 4801 recommended that a persistent set of parameters be generated 4802 upfront and saved. 4803 4804 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]`` 4805 Creates a TLS Pre-Shared Keys (PSK) credentials object, which 4806 can be used to provide TLS support on network backends. The 4807 ``id`` parameter is a unique ID which network backends will use 4808 to access the credentials. The ``endpoint`` is either ``server`` 4809 or ``client`` depending on whether the QEMU network backend that 4810 uses the credentials will be acting as a client or as a server. 4811 For clients only, ``username`` is the username which will be 4812 sent to the server. If omitted it defaults to "qemu". 4813 4814 The dir parameter tells QEMU where to find the keys file. It is 4815 called "dir/keys.psk" and contains "username:key" pairs. This 4816 file can most easily be created using the GnuTLS ``psktool`` 4817 program. 4818 4819 For server endpoints, dir may also contain a file dh-params.pem 4820 providing diffie-hellman parameters to use for the TLS server. 4821 If the file is missing, QEMU will generate a set of DH 4822 parameters at startup. This is a computationally expensive 4823 operation that consumes random pool entropy, so it is 4824 recommended that a persistent set of parameters be generated up 4825 front and saved. 4826 4827 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id`` 4828 Creates a TLS anonymous credentials object, which can be used to 4829 provide TLS support on network backends. The ``id`` parameter is 4830 a unique ID which network backends will use to access the 4831 credentials. The ``endpoint`` is either ``server`` or ``client`` 4832 depending on whether the QEMU network backend that uses the 4833 credentials will be acting as a client or as a server. If 4834 ``verify-peer`` is enabled (the default) then once the handshake 4835 is completed, the peer credentials will be verified. With x509 4836 certificates, this implies that the clients must be provided 4837 with valid client certificates too. 4838 4839 The dir parameter tells QEMU where to find the credential files. 4840 For server endpoints, this directory may contain a file 4841 dh-params.pem providing diffie-hellman parameters to use for the 4842 TLS server. If the file is missing, QEMU will generate a set of 4843 DH parameters at startup. This is a computationally expensive 4844 operation that consumes random pool entropy, so it is 4845 recommended that a persistent set of parameters be generated 4846 upfront and saved. 4847 4848 For x509 certificate credentials the directory will contain 4849 further files providing the x509 certificates. The certificates 4850 must be stored in PEM format, in filenames ca-cert.pem, 4851 ca-crl.pem (optional), server-cert.pem (only servers), 4852 server-key.pem (only servers), client-cert.pem (only clients), 4853 and client-key.pem (only clients). 4854 4855 For the server-key.pem and client-key.pem files which contain 4856 sensitive private keys, it is possible to use an encrypted 4857 version by providing the passwordid parameter. This provides the 4858 ID of a previously created ``secret`` object containing the 4859 password for decryption. 4860 4861 The priority parameter allows to override the global default 4862 priority used by gnutls. This can be useful if the system 4863 administrator needs to use a weaker set of crypto priorities for 4864 QEMU without potentially forcing the weakness onto all 4865 applications. Or conversely if one wants wants a stronger 4866 default for QEMU than for all other applications, they can do 4867 this through this parameter. Its format is a gnutls priority 4868 string as described at 4869 https://gnutls.org/manual/html_node/Priority-Strings.html. 4870 4871 ``-object tls-cipher-suites,id=id,priority=priority`` 4872 Creates a TLS cipher suites object, which can be used to control 4873 the TLS cipher/protocol algorithms that applications are permitted 4874 to use. 4875 4876 The ``id`` parameter is a unique ID which frontends will use to 4877 access the ordered list of permitted TLS cipher suites from the 4878 host. 4879 4880 The ``priority`` parameter allows to override the global default 4881 priority used by gnutls. This can be useful if the system 4882 administrator needs to use a weaker set of crypto priorities for 4883 QEMU without potentially forcing the weakness onto all 4884 applications. Or conversely if one wants wants a stronger 4885 default for QEMU than for all other applications, they can do 4886 this through this parameter. Its format is a gnutls priority 4887 string as described at 4888 https://gnutls.org/manual/html_node/Priority-Strings.html. 4889 4890 An example of use of this object is to control UEFI HTTPS Boot. 4891 The tls-cipher-suites object exposes the ordered list of permitted 4892 TLS cipher suites from the host side to the guest firmware, via 4893 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER 4894 objects. The firmware uses the IANA_TLS_CIPHER array for configuring 4895 guest-side TLS. 4896 4897 In the following example, the priority at which the host-side policy 4898 is retrieved is given by the ``priority`` property. 4899 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to 4900 refer to /etc/crypto-policies/back-ends/gnutls.config. 4901 4902 .. parsed-literal:: 4903 4904 # |qemu_system| \\ 4905 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\ 4906 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0 4907 4908 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]`` 4909 Interval t can't be 0, this filter batches the packet delivery: 4910 all packets arriving in a given interval on netdev netdevid are 4911 delayed until the end of the interval. Interval is in 4912 microseconds. ``status`` is optional that indicate whether the 4913 netfilter is on (enabled) or off (disabled), the default status 4914 for netfilter will be 'on'. 4915 4916 queue all\|rx\|tx is an option that can be applied to any 4917 netfilter. 4918 4919 ``all``: the filter is attached both to the receive and the 4920 transmit queue of the netdev (default). 4921 4922 ``rx``: the filter is attached to the receive queue of the 4923 netdev, where it will receive packets sent to the netdev. 4924 4925 ``tx``: the filter is attached to the transmit queue of the 4926 netdev, where it will receive packets sent by the netdev. 4927 4928 position head\|tail\|id=<id> is an option to specify where the 4929 filter should be inserted in the filter list. It can be applied 4930 to any netfilter. 4931 4932 ``head``: the filter is inserted at the head of the filter list, 4933 before any existing filters. 4934 4935 ``tail``: the filter is inserted at the tail of the filter list, 4936 behind any existing filters (default). 4937 4938 ``id=<id>``: the filter is inserted before or behind the filter 4939 specified by <id>, see the insert option below. 4940 4941 insert behind\|before is an option to specify where to insert 4942 the new filter relative to the one specified with 4943 position=id=<id>. It can be applied to any netfilter. 4944 4945 ``before``: insert before the specified filter. 4946 4947 ``behind``: insert behind the specified filter (default). 4948 4949 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 4950 filter-mirror on netdev netdevid,mirror net packet to 4951 chardevchardevid, if it has the vnet\_hdr\_support flag, 4952 filter-mirror will mirror packet with vnet\_hdr\_len. 4953 4954 ``-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]`` 4955 filter-redirector on netdev netdevid,redirect filter's net 4956 packet to chardev chardevid,and redirect indev's packet to 4957 filter.if it has the vnet\_hdr\_support flag, filter-redirector 4958 will redirect packet with vnet\_hdr\_len. Create a 4959 filter-redirector we need to differ outdev id from indev id, id 4960 can not be the same. we can just use indev or outdev, but at 4961 least one of indev or outdev need to be specified. 4962 4963 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 4964 Filter-rewriter is a part of COLO project.It will rewrite tcp 4965 packet to secondary from primary to keep secondary tcp 4966 connection,and rewrite tcp packet to primary from secondary make 4967 tcp packet can be handled by client.if it has the 4968 vnet\_hdr\_support flag, we can parse packet with vnet header. 4969 4970 usage: colo secondary: -object 4971 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object 4972 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object 4973 filter-rewriter,id=rew0,netdev=hn0,queue=all 4974 4975 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]`` 4976 Dump the network traffic on netdev dev to the file specified by 4977 filename. At most len bytes (64k by default) per packet are 4978 stored. The file format is libpcap, so it can be analyzed with 4979 tools such as tcpdump or Wireshark. 4980 4981 ``-object colo-compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=chardevid,iothread=id[,vnet_hdr_support][,notify_dev=id][,compare_timeout=@var{ms}][,expired_scan_cycle=@var{ms}][,max_queue_size=@var{size}]`` 4982 Colo-compare gets packet from primary\_in chardevid and 4983 secondary\_in, then compare whether the payload of primary packet 4984 and secondary packet are the same. If same, it will output 4985 primary packet to out\_dev, else it will notify COLO-framework to do 4986 checkpoint and send primary packet to out\_dev. In order to 4987 improve efficiency, we need to put the task of comparison in 4988 another iothread. If it has the vnet\_hdr\_support flag, 4989 colo compare will send/recv packet with vnet\_hdr\_len. 4990 The compare\_timeout=@var{ms} determines the maximum time of the 4991 colo-compare hold the packet. The expired\_scan\_cycle=@var{ms} 4992 is to set the period of scanning expired primary node network packets. 4993 The max\_queue\_size=@var{size} is to set the max compare queue 4994 size depend on user environment. 4995 If user want to use Xen COLO, need to add the notify\_dev to 4996 notify Xen colo-frame to do checkpoint. 4997 4998 COLO-compare must be used with the help of filter-mirror, 4999 filter-redirector and filter-rewriter. 5000 5001 :: 5002 5003 KVM COLO 5004 5005 primary: 5006 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5007 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5008 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5009 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5010 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5011 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5012 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5013 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5014 -object iothread,id=iothread1 5015 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5016 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5017 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5018 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1 5019 5020 secondary: 5021 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5022 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5023 -chardev socket,id=red0,host=3.3.3.3,port=9003 5024 -chardev socket,id=red1,host=3.3.3.3,port=9004 5025 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5026 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5027 5028 5029 Xen COLO 5030 5031 primary: 5032 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5033 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5034 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5035 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5036 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5037 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5038 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5039 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5040 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server=on,wait=off 5041 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5042 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5043 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5044 -object iothread,id=iothread1 5045 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1 5046 5047 secondary: 5048 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5049 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5050 -chardev socket,id=red0,host=3.3.3.3,port=9003 5051 -chardev socket,id=red1,host=3.3.3.3,port=9004 5052 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5053 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5054 5055 If you want to know the detail of above command line, you can 5056 read the colo-compare git log. 5057 5058 ``-object cryptodev-backend-builtin,id=id[,queues=queues]`` 5059 Creates a cryptodev backend which executes crypto opreation from 5060 the QEMU cipher APIS. The id parameter is a unique ID that will 5061 be used to reference this cryptodev backend from the 5062 ``virtio-crypto`` device. The queues parameter is optional, 5063 which specify the queue number of cryptodev backend, the default 5064 of queues is 1. 5065 5066 .. parsed-literal:: 5067 5068 # |qemu_system| \\ 5069 [...] \\ 5070 -object cryptodev-backend-builtin,id=cryptodev0 \\ 5071 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5072 [...] 5073 5074 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]`` 5075 Creates a vhost-user cryptodev backend, backed by a chardev 5076 chardevid. The id parameter is a unique ID that will be used to 5077 reference this cryptodev backend from the ``virtio-crypto`` 5078 device. The chardev should be a unix domain socket backed one. 5079 The vhost-user uses a specifically defined protocol to pass 5080 vhost ioctl replacement messages to an application on the other 5081 end of the socket. The queues parameter is optional, which 5082 specify the queue number of cryptodev backend for multiqueue 5083 vhost-user, the default of queues is 1. 5084 5085 .. parsed-literal:: 5086 5087 # |qemu_system| \\ 5088 [...] \\ 5089 -chardev socket,id=chardev0,path=/path/to/socket \\ 5090 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\ 5091 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5092 [...] 5093 5094 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]`` 5095 \ 5096 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]`` 5097 Defines a secret to store a password, encryption key, or some 5098 other sensitive data. The sensitive data can either be passed 5099 directly via the data parameter, or indirectly via the file 5100 parameter. Using the data parameter is insecure unless the 5101 sensitive data is encrypted. 5102 5103 The sensitive data can be provided in raw format (the default), 5104 or base64. When encoded as JSON, the raw format only supports 5105 valid UTF-8 characters, so base64 is recommended for sending 5106 binary data. QEMU will convert from which ever format is 5107 provided to the format it needs internally. eg, an RBD password 5108 can be provided in raw format, even though it will be base64 5109 encoded when passed onto the RBD sever. 5110 5111 For added protection, it is possible to encrypt the data 5112 associated with a secret using the AES-256-CBC cipher. Use of 5113 encryption is indicated by providing the keyid and iv 5114 parameters. The keyid parameter provides the ID of a previously 5115 defined secret that contains the AES-256 decryption key. This 5116 key should be 32-bytes long and be base64 encoded. The iv 5117 parameter provides the random initialization vector used for 5118 encryption of this particular secret and should be a base64 5119 encrypted string of the 16-byte IV. 5120 5121 The simplest (insecure) usage is to provide the secret inline 5122 5123 .. parsed-literal:: 5124 5125 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw 5126 5127 The simplest secure usage is to provide the secret via a file 5128 5129 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object 5130 secret,id=sec0,file=mypasswd.txt,format=raw 5131 5132 For greater security, AES-256-CBC should be used. To illustrate 5133 usage, consider the openssl command line tool which can encrypt 5134 the data. Note that when encrypting, the plaintext must be 5135 padded to the cipher block size (32 bytes) using the standard 5136 PKCS#5/6 compatible padding algorithm. 5137 5138 First a master key needs to be created in base64 encoding: 5139 5140 :: 5141 5142 # openssl rand -base64 32 > key.b64 5143 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"') 5144 5145 Each secret to be encrypted needs to have a random 5146 initialization vector generated. These do not need to be kept 5147 secret 5148 5149 :: 5150 5151 # openssl rand -base64 16 > iv.b64 5152 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"') 5153 5154 The secret to be defined can now be encrypted, in this case 5155 we're telling openssl to base64 encode the result, but it could 5156 be left as raw bytes if desired. 5157 5158 :: 5159 5160 # SECRET=$(printf "letmein" | 5161 openssl enc -aes-256-cbc -a -K $KEY -iv $IV) 5162 5163 When launching QEMU, create a master secret pointing to 5164 ``key.b64`` and specify that to be used to decrypt the user 5165 password. Pass the contents of ``iv.b64`` to the second secret 5166 5167 .. parsed-literal:: 5168 5169 # |qemu_system| \\ 5170 -object secret,id=secmaster0,format=base64,file=key.b64 \\ 5171 -object secret,id=sec0,keyid=secmaster0,format=base64,\\ 5172 data=$SECRET,iv=$(<iv.b64) 5173 5174 ``-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]`` 5175 Create a Secure Encrypted Virtualization (SEV) guest object, 5176 which can be used to provide the guest memory encryption support 5177 on AMD processors. 5178 5179 When memory encryption is enabled, one of the physical address 5180 bit (aka the C-bit) is utilized to mark if a memory page is 5181 protected. The ``cbitpos`` is used to provide the C-bit 5182 position. The C-bit position is Host family dependent hence user 5183 must provide this value. On EPYC, the value should be 47. 5184 5185 When memory encryption is enabled, we loose certain bits in 5186 physical address space. The ``reduced-phys-bits`` is used to 5187 provide the number of bits we loose in physical address space. 5188 Similar to C-bit, the value is Host family dependent. On EPYC, 5189 the value should be 5. 5190 5191 The ``sev-device`` provides the device file to use for 5192 communicating with the SEV firmware running inside AMD Secure 5193 Processor. The default device is '/dev/sev'. If hardware 5194 supports memory encryption then /dev/sev devices are created by 5195 CCP driver. 5196 5197 The ``policy`` provides the guest policy to be enforced by the 5198 SEV firmware and restrict what configuration and operational 5199 commands can be performed on this guest by the hypervisor. The 5200 policy should be provided by the guest owner and is bound to the 5201 guest and cannot be changed throughout the lifetime of the 5202 guest. The default is 0. 5203 5204 If guest ``policy`` allows sharing the key with another SEV 5205 guest then ``handle`` can be use to provide handle of the guest 5206 from which to share the key. 5207 5208 The ``dh-cert-file`` and ``session-file`` provides the guest 5209 owner's Public Diffie-Hillman key defined in SEV spec. The PDH 5210 and session parameters are used for establishing a cryptographic 5211 session with the guest owner to negotiate keys used for 5212 attestation. The file must be encoded in base64. 5213 5214 e.g to launch a SEV guest 5215 5216 .. parsed-literal:: 5217 5218 # |qemu_system_x86| \\ 5219 ...... \\ 5220 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\ 5221 -machine ...,memory-encryption=sev0 \\ 5222 ..... 5223 5224 ``-object authz-simple,id=id,identity=string`` 5225 Create an authorization object that will control access to 5226 network services. 5227 5228 The ``identity`` parameter is identifies the user and its format 5229 depends on the network service that authorization object is 5230 associated with. For authorizing based on TLS x509 certificates, 5231 the identity must be the x509 distinguished name. Note that care 5232 must be taken to escape any commas in the distinguished name. 5233 5234 An example authorization object to validate a x509 distinguished 5235 name would look like: 5236 5237 .. parsed-literal:: 5238 5239 # |qemu_system| \\ 5240 ... \\ 5241 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\ 5242 ... 5243 5244 Note the use of quotes due to the x509 distinguished name 5245 containing whitespace, and escaping of ','. 5246 5247 ``-object authz-listfile,id=id,filename=path,refresh=on|off`` 5248 Create an authorization object that will control access to 5249 network services. 5250 5251 The ``filename`` parameter is the fully qualified path to a file 5252 containing the access control list rules in JSON format. 5253 5254 An example set of rules that match against SASL usernames might 5255 look like: 5256 5257 :: 5258 5259 { 5260 "rules": [ 5261 { "match": "fred", "policy": "allow", "format": "exact" }, 5262 { "match": "bob", "policy": "allow", "format": "exact" }, 5263 { "match": "danb", "policy": "deny", "format": "glob" }, 5264 { "match": "dan*", "policy": "allow", "format": "exact" }, 5265 ], 5266 "policy": "deny" 5267 } 5268 5269 When checking access the object will iterate over all the rules 5270 and the first rule to match will have its ``policy`` value 5271 returned as the result. If no rules match, then the default 5272 ``policy`` value is returned. 5273 5274 The rules can either be an exact string match, or they can use 5275 the simple UNIX glob pattern matching to allow wildcards to be 5276 used. 5277 5278 If ``refresh`` is set to true the file will be monitored and 5279 automatically reloaded whenever its content changes. 5280 5281 As with the ``authz-simple`` object, the format of the identity 5282 strings being matched depends on the network service, but is 5283 usually a TLS x509 distinguished name, or a SASL username. 5284 5285 An example authorization object to validate a SASL username 5286 would look like: 5287 5288 .. parsed-literal:: 5289 5290 # |qemu_system| \\ 5291 ... \\ 5292 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\ 5293 ... 5294 5295 ``-object authz-pam,id=id,service=string`` 5296 Create an authorization object that will control access to 5297 network services. 5298 5299 The ``service`` parameter provides the name of a PAM service to 5300 use for authorization. It requires that a file 5301 ``/etc/pam.d/service`` exist to provide the configuration for 5302 the ``account`` subsystem. 5303 5304 An example authorization object to validate a TLS x509 5305 distinguished name would look like: 5306 5307 .. parsed-literal:: 5308 5309 # |qemu_system| \\ 5310 ... \\ 5311 -object authz-pam,id=auth0,service=qemu-vnc \\ 5312 ... 5313 5314 There would then be a corresponding config file for PAM at 5315 ``/etc/pam.d/qemu-vnc`` that contains: 5316 5317 :: 5318 5319 account requisite pam_listfile.so item=user sense=allow \ 5320 file=/etc/qemu/vnc.allow 5321 5322 Finally the ``/etc/qemu/vnc.allow`` file would contain the list 5323 of x509 distingished names that are permitted access 5324 5325 :: 5326 5327 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB 5328 5329 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch`` 5330 Creates a dedicated event loop thread that devices can be 5331 assigned to. This is known as an IOThread. By default device 5332 emulation happens in vCPU threads or the main event loop thread. 5333 This can become a scalability bottleneck. IOThreads allow device 5334 emulation and I/O to run on other host CPUs. 5335 5336 The ``id`` parameter is a unique ID that will be used to 5337 reference this IOThread from ``-device ...,iothread=id``. 5338 Multiple devices can be assigned to an IOThread. Note that not 5339 all devices support an ``iothread`` parameter. 5340 5341 The ``query-iothreads`` QMP command lists IOThreads and reports 5342 their thread IDs so that the user can configure host CPU 5343 pinning/affinity. 5344 5345 IOThreads use an adaptive polling algorithm to reduce event loop 5346 latency. Instead of entering a blocking system call to monitor 5347 file descriptors and then pay the cost of being woken up when an 5348 event occurs, the polling algorithm spins waiting for events for 5349 a short time. The algorithm's default parameters are suitable 5350 for many cases but can be adjusted based on knowledge of the 5351 workload and/or host device latency. 5352 5353 The ``poll-max-ns`` parameter is the maximum number of 5354 nanoseconds to busy wait for events. Polling can be disabled by 5355 setting this value to 0. 5356 5357 The ``poll-grow`` parameter is the multiplier used to increase 5358 the polling time when the algorithm detects it is missing events 5359 due to not polling long enough. 5360 5361 The ``poll-shrink`` parameter is the divisor used to decrease 5362 the polling time when the algorithm detects it is spending too 5363 long polling without encountering events. 5364 5365 The ``aio-max-batch`` parameter is the maximum number of requests 5366 in a batch for the AIO engine, 0 means that the engine will use 5367 its default. 5368 5369 The IOThread parameters can be modified at run-time using the 5370 ``qom-set`` command (where ``iothread1`` is the IOThread's 5371 ``id``): 5372 5373 :: 5374 5375 (qemu) qom-set /objects/iothread1 poll-max-ns 100000 5376ERST 5377 5378 5379HXCOMM This is the last statement. Insert new options before this line! 5380 5381#undef DEF 5382#undef DEFHEADING 5383#undef ARCHHEADING 5384
