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,sgx-epc.0.node=numaid\n", 131 QEMU_ARCH_ALL) 132 133SRST 134``sgx-epc.0.memdev=@var{memid},sgx-epc.0.node=@var{numaid}`` 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][,clusters=clusters][,cores=cores][,threads=threads]\n" 210 " set the number of initial 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 sockets on the machine board\n" 214 " dies= number of dies in one socket\n" 215 " clusters= number of clusters in one die\n" 216 " cores= number of cores in one cluster\n" 217 " threads= number of threads in one core\n" 218 "Note: Different machines may have different subsets of the CPU topology\n" 219 " parameters supported, so the actual meaning of the supported parameters\n" 220 " will vary accordingly. For example, for a machine type that supports a\n" 221 " three-level CPU hierarchy of sockets/cores/threads, the parameters will\n" 222 " sequentially mean as below:\n" 223 " sockets means the number of sockets on the machine board\n" 224 " cores means the number of cores in one socket\n" 225 " threads means the number of threads in one core\n" 226 " For a particular machine type board, an expected CPU topology hierarchy\n" 227 " can be defined through the supported sub-option. Unsupported parameters\n" 228 " can also be provided in addition to the sub-option, but their values\n" 229 " must be set as 1 in the purpose of correct parsing.\n", 230 QEMU_ARCH_ALL) 231SRST 232``-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]`` 233 Simulate a SMP system with '\ ``n``\ ' CPUs initially present on 234 the machine type board. On boards supporting CPU hotplug, the optional 235 '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be 236 added at runtime. When both parameters are omitted, the maximum number 237 of CPUs will be calculated from the provided topology members and the 238 initial CPU count will match the maximum number. When only one of them 239 is given then the omitted one will be set to its counterpart's value. 240 Both parameters may be specified, but the maximum number of CPUs must 241 be equal to or greater than the initial CPU count. Product of the 242 CPU topology hierarchy must be equal to the maximum number of CPUs. 243 Both parameters are subject to an upper limit that is determined by 244 the specific machine type chosen. 245 246 To control reporting of CPU topology information, values of the topology 247 parameters can be specified. Machines may only support a subset of the 248 parameters and different machines may have different subsets supported 249 which vary depending on capacity of the corresponding CPU targets. So 250 for a particular machine type board, an expected topology hierarchy can 251 be defined through the supported sub-option. Unsupported parameters can 252 also be provided in addition to the sub-option, but their values must be 253 set as 1 in the purpose of correct parsing. 254 255 Either the initial CPU count, or at least one of the topology parameters 256 must be specified. The specified parameters must be greater than zero, 257 explicit configuration like "cpus=0" is not allowed. Values for any 258 omitted parameters will be computed from those which are given. 259 260 For example, the following sub-option defines a CPU topology hierarchy 261 (2 sockets totally on the machine, 2 cores per socket, 2 threads per 262 core) for a machine that only supports sockets/cores/threads. 263 Some members of the option can be omitted but their values will be 264 automatically computed: 265 266 :: 267 268 -smp 8,sockets=2,cores=2,threads=2,maxcpus=8 269 270 The following sub-option defines a CPU topology hierarchy (2 sockets 271 totally on the machine, 2 dies per socket, 2 cores per die, 2 threads 272 per core) for PC machines which support sockets/dies/cores/threads. 273 Some members of the option can be omitted but their values will be 274 automatically computed: 275 276 :: 277 278 -smp 16,sockets=2,dies=2,cores=2,threads=2,maxcpus=16 279 280 The following sub-option defines a CPU topology hierarchy (2 sockets 281 totally on the machine, 2 clusters per socket, 2 cores per cluster, 282 2 threads per core) for ARM virt machines which support sockets/clusters 283 /cores/threads. Some members of the option can be omitted but their values 284 will be automatically computed: 285 286 :: 287 288 -smp 16,sockets=2,clusters=2,cores=2,threads=2,maxcpus=16 289 290 Historically preference was given to the coarsest topology parameters 291 when computing missing values (ie sockets preferred over cores, which 292 were preferred over threads), however, this behaviour is considered 293 liable to change. Prior to 6.2 the preference was sockets over cores 294 over threads. Since 6.2 the preference is cores over sockets over threads. 295 296 For example, the following option defines a machine board with 2 sockets 297 of 1 core before 6.2 and 1 socket of 2 cores after 6.2: 298 299 :: 300 301 -smp 2 302ERST 303 304DEF("numa", HAS_ARG, QEMU_OPTION_numa, 305 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 306 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 307 "-numa dist,src=source,dst=destination,val=distance\n" 308 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n" 309 "-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" 310 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n", 311 QEMU_ARCH_ALL) 312SRST 313``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 314 \ 315``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 316 \ 317``-numa dist,src=source,dst=destination,val=distance`` 318 \ 319``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]`` 320 \ 321``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]`` 322 \ 323``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]`` 324 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA 325 distance from a source node to a destination node. Set the ACPI 326 Heterogeneous Memory Attributes for the given nodes. 327 328 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and 329 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a 330 contiguous range of CPU indexes (or a single VCPU if lastcpu is 331 omitted). A non-contiguous set of VCPUs can be represented by 332 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is 333 omitted on all nodes, VCPUs are automatically split between them. 334 335 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a 336 NUMA node: 337 338 :: 339 340 -numa node,cpus=0-2,cpus=5 341 342 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option 343 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to 344 assign CPU objects to a node using topology layout properties of 345 CPU. The set of properties is machine specific, and depends on used 346 machine type/'\ ``smp``\ ' options. It could be queried with 347 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ ' 348 property specifies node to which CPU object will be assigned, it's 349 required for node to be declared with '\ ``node``\ ' option before 350 it's used with '\ ``cpu``\ ' option. 351 352 For example: 353 354 :: 355 356 -M pc \ 357 -smp 1,sockets=2,maxcpus=2 \ 358 -numa node,nodeid=0 -numa node,nodeid=1 \ 359 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1 360 361 Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported 362 for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from 363 a given memory backend device to a node. If '\ ``mem``\ ' and 364 '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them. 365 366 367 '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive. 368 Furthermore, if one node uses '\ ``memdev``\ ', all of them have to 369 use it. 370 371 '\ ``initiator``\ ' is an additional option that points to an 372 initiator NUMA node that has best performance (the lowest latency or 373 largest bandwidth) to this NUMA node. Note that this option can be 374 set only when the machine property 'hmat' is set to 'on'. 375 376 Following example creates a machine with 2 NUMA nodes, node 0 has 377 CPU. node 1 has only memory, and its initiator is node 0. Note that 378 because node 0 has CPU, by default the initiator of node 0 is itself 379 and must be itself. 380 381 :: 382 383 -machine hmat=on \ 384 -m 2G,slots=2,maxmem=4G \ 385 -object memory-backend-ram,size=1G,id=m0 \ 386 -object memory-backend-ram,size=1G,id=m1 \ 387 -numa node,nodeid=0,memdev=m0 \ 388 -numa node,nodeid=1,memdev=m1,initiator=0 \ 389 -smp 2,sockets=2,maxcpus=2 \ 390 -numa cpu,node-id=0,socket-id=0 \ 391 -numa cpu,node-id=0,socket-id=1 392 393 source and destination are NUMA node IDs. distance is the NUMA 394 distance from source to destination. The distance from a node to 395 itself is always 10. If any pair of nodes is given a distance, then 396 all pairs must be given distances. Although, when distances are only 397 given in one direction for each pair of nodes, then the distances in 398 the opposite directions are assumed to be the same. If, however, an 399 asymmetrical pair of distances is given for even one node pair, then 400 all node pairs must be provided distance values for both directions, 401 even when they are symmetrical. When a node is unreachable from 402 another node, set the pair's distance to 255. 403 404 Note that the -``numa`` option doesn't allocate any of the specified 405 resources, it just assigns existing resources to NUMA nodes. This 406 means that one still has to use the ``-m``, ``-smp`` options to 407 allocate RAM and VCPUs respectively. 408 409 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth 410 Information between initiator and target NUMA nodes in ACPI 411 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can 412 create memory requests, usually it has one or more processors. 413 Target NUMA node contains addressable memory. 414 415 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is 416 the memory hierarchy of the target NUMA node: if hierarchy is 417 'memory', the structure represents the memory performance; if 418 hierarchy is 'first-level\|second-level\|third-level', this 419 structure represents aggregated performance of memory side caches 420 for each domain. type of 'data-type' is type of data represented by 421 this structure instance: if 'hierarchy' is 'memory', 'data-type' is 422 'access\|read\|write' latency or 'access\|read\|write' bandwidth of 423 the target memory; if 'hierarchy' is 424 'first-level\|second-level\|third-level', 'data-type' is 425 'access\|read\|write' hit latency or 'access\|read\|write' hit 426 bandwidth of the target memory side cache. 427 428 lat is latency value in nanoseconds. bw is bandwidth value, the 429 possible value and units are NUM[M\|G\|T], mean that the bandwidth 430 value are NUM byte per second (or MB/s, GB/s or TB/s depending on 431 used suffix). Note that if latency or bandwidth value is 0, means 432 the corresponding latency or bandwidth information is not provided. 433 434 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory 435 belongs. size is the size of memory side cache in bytes. level is 436 the cache level described in this structure, note that the cache 437 level 0 should not be used with '\ ``hmat-cache``\ ' option. 438 associativity is the cache associativity, the possible value is 439 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy 440 is the write policy. line is the cache Line size in bytes. 441 442 For example, the following options describe 2 NUMA nodes. Node 0 has 443 2 cpus and a ram, node 1 has only a ram. The processors in node 0 444 access memory in node 0 with access-latency 5 nanoseconds, 445 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access 446 memory in NUMA node 1 with access-latency 10 nanoseconds, 447 access-bandwidth is 100 MB/s. And for memory side cache information, 448 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB, 449 policy is write-back, the cache Line size is 8 bytes: 450 451 :: 452 453 -machine hmat=on \ 454 -m 2G \ 455 -object memory-backend-ram,size=1G,id=m0 \ 456 -object memory-backend-ram,size=1G,id=m1 \ 457 -smp 2,sockets=2,maxcpus=2 \ 458 -numa node,nodeid=0,memdev=m0 \ 459 -numa node,nodeid=1,memdev=m1,initiator=0 \ 460 -numa cpu,node-id=0,socket-id=0 \ 461 -numa cpu,node-id=0,socket-id=1 \ 462 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \ 463 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \ 464 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \ 465 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \ 466 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \ 467 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8 468ERST 469 470DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd, 471 "-add-fd fd=fd,set=set[,opaque=opaque]\n" 472 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL) 473SRST 474``-add-fd fd=fd,set=set[,opaque=opaque]`` 475 Add a file descriptor to an fd set. Valid options are: 476 477 ``fd=fd`` 478 This option defines the file descriptor of which a duplicate is 479 added to fd set. The file descriptor cannot be stdin, stdout, or 480 stderr. 481 482 ``set=set`` 483 This option defines the ID of the fd set to add the file 484 descriptor to. 485 486 ``opaque=opaque`` 487 This option defines a free-form string that can be used to 488 describe fd. 489 490 You can open an image using pre-opened file descriptors from an fd 491 set: 492 493 .. parsed-literal:: 494 495 |qemu_system| \\ 496 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 497 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 498 -drive file=/dev/fdset/2,index=0,media=disk 499ERST 500 501DEF("set", HAS_ARG, QEMU_OPTION_set, 502 "-set group.id.arg=value\n" 503 " set <arg> parameter for item <id> of type <group>\n" 504 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL) 505SRST 506``-set group.id.arg=value`` 507 Set parameter arg for item id of type group 508ERST 509 510DEF("global", HAS_ARG, QEMU_OPTION_global, 511 "-global driver.property=value\n" 512 "-global driver=driver,property=property,value=value\n" 513 " set a global default for a driver property\n", 514 QEMU_ARCH_ALL) 515SRST 516``-global driver.prop=value`` 517 \ 518``-global driver=driver,property=property,value=value`` 519 Set default value of driver's property prop to value, e.g.: 520 521 .. parsed-literal:: 522 523 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img 524 525 In particular, you can use this to set driver properties for devices 526 which are created automatically by the machine model. To create a 527 device which is not created automatically and set properties on it, 528 use -``device``. 529 530 -global driver.prop=value is shorthand for -global 531 driver=driver,property=prop,value=value. The longhand syntax works 532 even when driver contains a dot. 533ERST 534 535DEF("boot", HAS_ARG, QEMU_OPTION_boot, 536 "-boot [order=drives][,once=drives][,menu=on|off]\n" 537 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n" 538 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n" 539 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n" 540 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n" 541 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n", 542 QEMU_ARCH_ALL) 543SRST 544``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]`` 545 Specify boot order drives as a string of drive letters. Valid drive 546 letters depend on the target architecture. The x86 PC uses: a, b 547 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p 548 (Etherboot from network adapter 1-4), hard disk boot is the default. 549 To apply a particular boot order only on the first startup, specify 550 it via ``once``. Note that the ``order`` or ``once`` parameter 551 should not be used together with the ``bootindex`` property of 552 devices, since the firmware implementations normally do not support 553 both at the same time. 554 555 Interactive boot menus/prompts can be enabled via ``menu=on`` as far 556 as firmware/BIOS supports them. The default is non-interactive boot. 557 558 A splash picture could be passed to bios, enabling user to show it 559 as logo, when option splash=sp\_name is given and menu=on, If 560 firmware/BIOS supports them. Currently Seabios for X86 system 561 support it. limitation: The splash file could be a jpeg file or a 562 BMP file in 24 BPP format(true color). The resolution should be 563 supported by the SVGA mode, so the recommended is 320x240, 640x480, 564 800x640. 565 566 A timeout could be passed to bios, guest will pause for rb\_timeout 567 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will 568 not reboot, qemu passes '-1' to bios by default. Currently Seabios 569 for X86 system support it. 570 571 Do strict boot via ``strict=on`` as far as firmware/BIOS supports 572 it. This only effects when boot priority is changed by bootindex 573 options. The default is non-strict boot. 574 575 .. parsed-literal:: 576 577 # try to boot from network first, then from hard disk 578 |qemu_system_x86| -boot order=nc 579 # boot from CD-ROM first, switch back to default order after reboot 580 |qemu_system_x86| -boot once=d 581 # boot with a splash picture for 5 seconds. 582 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000 583 584 Note: The legacy format '-boot drives' is still supported but its 585 use is discouraged as it may be removed from future versions. 586ERST 587 588DEF("m", HAS_ARG, QEMU_OPTION_m, 589 "-m [size=]megs[,slots=n,maxmem=size]\n" 590 " configure guest RAM\n" 591 " size: initial amount of guest memory\n" 592 " slots: number of hotplug slots (default: none)\n" 593 " maxmem: maximum amount of guest memory (default: none)\n" 594 "NOTE: Some architectures might enforce a specific granularity\n", 595 QEMU_ARCH_ALL) 596SRST 597``-m [size=]megs[,slots=n,maxmem=size]`` 598 Sets guest startup RAM size to megs megabytes. Default is 128 MiB. 599 Optionally, a suffix of "M" or "G" can be used to signify a value in 600 megabytes or gigabytes respectively. Optional pair slots, maxmem 601 could be used to set amount of hotpluggable memory slots and maximum 602 amount of memory. Note that maxmem must be aligned to the page size. 603 604 For example, the following command-line sets the guest startup RAM 605 size to 1GB, creates 3 slots to hotplug additional memory and sets 606 the maximum memory the guest can reach to 4GB: 607 608 .. parsed-literal:: 609 610 |qemu_system| -m 1G,slots=3,maxmem=4G 611 612 If slots and maxmem are not specified, memory hotplug won't be 613 enabled and the guest startup RAM will never increase. 614ERST 615 616DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath, 617 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL) 618SRST 619``-mem-path path`` 620 Allocate guest RAM from a temporarily created file in path. 621ERST 622 623DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc, 624 "-mem-prealloc preallocate guest memory (use with -mem-path)\n", 625 QEMU_ARCH_ALL) 626SRST 627``-mem-prealloc`` 628 Preallocate memory when using -mem-path. 629ERST 630 631DEF("k", HAS_ARG, QEMU_OPTION_k, 632 "-k language use keyboard layout (for example 'fr' for French)\n", 633 QEMU_ARCH_ALL) 634SRST 635``-k language`` 636 Use keyboard layout language (for example ``fr`` for French). This 637 option is only needed where it is not easy to get raw PC keycodes 638 (e.g. on Macs, with some X11 servers or with a VNC or curses 639 display). You don't normally need to use it on PC/Linux or 640 PC/Windows hosts. 641 642 The available layouts are: 643 644 :: 645 646 ar de-ch es fo fr-ca hu ja mk no pt-br sv 647 da en-gb et fr fr-ch is lt nl pl ru th 648 de en-us fi fr-be hr it lv nl-be pt sl tr 649 650 The default is ``en-us``. 651ERST 652 653 654HXCOMM Deprecated by -audiodev 655DEF("audio-help", 0, QEMU_OPTION_audio_help, 656 "-audio-help show -audiodev equivalent of the currently specified audio settings\n", 657 QEMU_ARCH_ALL) 658SRST 659``-audio-help`` 660 Will show the -audiodev equivalent of the currently specified 661 (deprecated) environment variables. 662ERST 663 664DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev, 665 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n" 666 " specifies the audio backend to use\n" 667 " id= identifier of the backend\n" 668 " timer-period= timer period in microseconds\n" 669 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n" 670 " in|out.fixed-settings= use fixed settings for host audio\n" 671 " in|out.frequency= frequency to use with fixed settings\n" 672 " in|out.channels= number of channels to use with fixed settings\n" 673 " in|out.format= sample format to use with fixed settings\n" 674 " valid values: s8, s16, s32, u8, u16, u32, f32\n" 675 " in|out.voices= number of voices to use\n" 676 " in|out.buffer-length= length of buffer in microseconds\n" 677 "-audiodev none,id=id,[,prop[=value][,...]]\n" 678 " dummy driver that discards all output\n" 679#ifdef CONFIG_AUDIO_ALSA 680 "-audiodev alsa,id=id[,prop[=value][,...]]\n" 681 " in|out.dev= name of the audio device to use\n" 682 " in|out.period-length= length of period in microseconds\n" 683 " in|out.try-poll= attempt to use poll mode\n" 684 " threshold= threshold (in microseconds) when playback starts\n" 685#endif 686#ifdef CONFIG_AUDIO_COREAUDIO 687 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n" 688 " in|out.buffer-count= number of buffers\n" 689#endif 690#ifdef CONFIG_AUDIO_DSOUND 691 "-audiodev dsound,id=id[,prop[=value][,...]]\n" 692 " latency= add extra latency to playback in microseconds\n" 693#endif 694#ifdef CONFIG_AUDIO_OSS 695 "-audiodev oss,id=id[,prop[=value][,...]]\n" 696 " in|out.dev= path of the audio device to use\n" 697 " in|out.buffer-count= number of buffers\n" 698 " in|out.try-poll= attempt to use poll mode\n" 699 " try-mmap= try using memory mapped access\n" 700 " exclusive= open device in exclusive mode\n" 701 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n" 702#endif 703#ifdef CONFIG_AUDIO_PA 704 "-audiodev pa,id=id[,prop[=value][,...]]\n" 705 " server= PulseAudio server address\n" 706 " in|out.name= source/sink device name\n" 707 " in|out.latency= desired latency in microseconds\n" 708#endif 709#ifdef CONFIG_AUDIO_SDL 710 "-audiodev sdl,id=id[,prop[=value][,...]]\n" 711 " in|out.buffer-count= number of buffers\n" 712#endif 713#ifdef CONFIG_SPICE 714 "-audiodev spice,id=id[,prop[=value][,...]]\n" 715#endif 716#ifdef CONFIG_DBUS_DISPLAY 717 "-audiodev dbus,id=id[,prop[=value][,...]]\n" 718#endif 719 "-audiodev wav,id=id[,prop[=value][,...]]\n" 720 " path= path of wav file to record\n", 721 QEMU_ARCH_ALL) 722SRST 723``-audiodev [driver=]driver,id=id[,prop[=value][,...]]`` 724 Adds a new audio backend driver identified by id. There are global 725 and driver specific properties. Some values can be set differently 726 for input and output, they're marked with ``in|out.``. You can set 727 the input's property with ``in.prop`` and the output's property with 728 ``out.prop``. For example: 729 730 :: 731 732 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000 733 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified 734 735 NOTE: parameter validation is known to be incomplete, in many cases 736 specifying an invalid option causes QEMU to print an error message 737 and continue emulation without sound. 738 739 Valid global options are: 740 741 ``id=identifier`` 742 Identifies the audio backend. 743 744 ``timer-period=period`` 745 Sets the timer period used by the audio subsystem in 746 microseconds. Default is 10000 (10 ms). 747 748 ``in|out.mixing-engine=on|off`` 749 Use QEMU's mixing engine to mix all streams inside QEMU and 750 convert audio formats when not supported by the backend. When 751 off, fixed-settings must be off too. Note that disabling this 752 option means that the selected backend must support multiple 753 streams and the audio formats used by the virtual cards, 754 otherwise you'll get no sound. It's not recommended to disable 755 this option unless you want to use 5.1 or 7.1 audio, as mixing 756 engine only supports mono and stereo audio. Default is on. 757 758 ``in|out.fixed-settings=on|off`` 759 Use fixed settings for host audio. When off, it will change 760 based on how the guest opens the sound card. In this case you 761 must not specify frequency, channels or format. Default is on. 762 763 ``in|out.frequency=frequency`` 764 Specify the frequency to use when using fixed-settings. Default 765 is 44100Hz. 766 767 ``in|out.channels=channels`` 768 Specify the number of channels to use when using fixed-settings. 769 Default is 2 (stereo). 770 771 ``in|out.format=format`` 772 Specify the sample format to use when using fixed-settings. 773 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``, 774 ``u32``, ``f32``. Default is ``s16``. 775 776 ``in|out.voices=voices`` 777 Specify the number of voices to use. Default is 1. 778 779 ``in|out.buffer-length=usecs`` 780 Sets the size of the buffer in microseconds. 781 782``-audiodev none,id=id[,prop[=value][,...]]`` 783 Creates a dummy backend that discards all outputs. This backend has 784 no backend specific properties. 785 786``-audiodev alsa,id=id[,prop[=value][,...]]`` 787 Creates backend using the ALSA. This backend is only available on 788 Linux. 789 790 ALSA specific options are: 791 792 ``in|out.dev=device`` 793 Specify the ALSA device to use for input and/or output. Default 794 is ``default``. 795 796 ``in|out.period-length=usecs`` 797 Sets the period length in microseconds. 798 799 ``in|out.try-poll=on|off`` 800 Attempt to use poll mode with the device. Default is on. 801 802 ``threshold=threshold`` 803 Threshold (in microseconds) when playback starts. Default is 0. 804 805``-audiodev coreaudio,id=id[,prop[=value][,...]]`` 806 Creates a backend using Apple's Core Audio. This backend is only 807 available on Mac OS and only supports playback. 808 809 Core Audio specific options are: 810 811 ``in|out.buffer-count=count`` 812 Sets the count of the buffers. 813 814``-audiodev dsound,id=id[,prop[=value][,...]]`` 815 Creates a backend using Microsoft's DirectSound. This backend is 816 only available on Windows and only supports playback. 817 818 DirectSound specific options are: 819 820 ``latency=usecs`` 821 Add extra usecs microseconds latency to playback. Default is 822 10000 (10 ms). 823 824``-audiodev oss,id=id[,prop[=value][,...]]`` 825 Creates a backend using OSS. This backend is available on most 826 Unix-like systems. 827 828 OSS specific options are: 829 830 ``in|out.dev=device`` 831 Specify the file name of the OSS device to use. Default is 832 ``/dev/dsp``. 833 834 ``in|out.buffer-count=count`` 835 Sets the count of the buffers. 836 837 ``in|out.try-poll=on|of`` 838 Attempt to use poll mode with the device. Default is on. 839 840 ``try-mmap=on|off`` 841 Try using memory mapped device access. Default is off. 842 843 ``exclusive=on|off`` 844 Open the device in exclusive mode (vmix won't work in this 845 case). Default is off. 846 847 ``dsp-policy=policy`` 848 Sets the timing policy (between 0 and 10, where smaller number 849 means smaller latency but higher CPU usage). Use -1 to use 850 buffer sizes specified by ``buffer`` and ``buffer-count``. This 851 option is ignored if you do not have OSS 4. Default is 5. 852 853``-audiodev pa,id=id[,prop[=value][,...]]`` 854 Creates a backend using PulseAudio. This backend is available on 855 most systems. 856 857 PulseAudio specific options are: 858 859 ``server=server`` 860 Sets the PulseAudio server to connect to. 861 862 ``in|out.name=sink`` 863 Use the specified source/sink for recording/playback. 864 865 ``in|out.latency=usecs`` 866 Desired latency in microseconds. The PulseAudio server will try 867 to honor this value but actual latencies may be lower or higher. 868 869``-audiodev sdl,id=id[,prop[=value][,...]]`` 870 Creates a backend using SDL. This backend is available on most 871 systems, but you should use your platform's native backend if 872 possible. 873 874 SDL specific options are: 875 876 ``in|out.buffer-count=count`` 877 Sets the count of the buffers. 878 879``-audiodev spice,id=id[,prop[=value][,...]]`` 880 Creates a backend that sends audio through SPICE. This backend 881 requires ``-spice`` and automatically selected in that case, so 882 usually you can ignore this option. This backend has no backend 883 specific properties. 884 885``-audiodev wav,id=id[,prop[=value][,...]]`` 886 Creates a backend that writes audio to a WAV file. 887 888 Backend specific options are: 889 890 ``path=path`` 891 Write recorded audio into the specified file. Default is 892 ``qemu.wav``. 893ERST 894 895DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw, 896 "-soundhw c1,... enable audio support\n" 897 " and only specified sound cards (comma separated list)\n" 898 " use '-soundhw help' to get the list of supported cards\n" 899 " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL) 900SRST 901``-soundhw card1[,card2,...] or -soundhw all`` 902 Enable audio and selected sound hardware. Use 'help' to print all 903 available sound hardware. For example: 904 905 .. parsed-literal:: 906 907 |qemu_system_x86| -soundhw sb16,adlib disk.img 908 |qemu_system_x86| -soundhw es1370 disk.img 909 |qemu_system_x86| -soundhw ac97 disk.img 910 |qemu_system_x86| -soundhw hda disk.img 911 |qemu_system_x86| -soundhw all disk.img 912 |qemu_system_x86| -soundhw help 913 914 Note that Linux's i810\_audio OSS kernel (for AC97) module might 915 require manually specifying clocking. 916 917 :: 918 919 modprobe i810_audio clocking=48000 920ERST 921 922DEF("device", HAS_ARG, QEMU_OPTION_device, 923 "-device driver[,prop[=value][,...]]\n" 924 " add device (based on driver)\n" 925 " prop=value,... sets driver properties\n" 926 " use '-device help' to print all possible drivers\n" 927 " use '-device driver,help' to print all possible properties\n", 928 QEMU_ARCH_ALL) 929SRST 930``-device driver[,prop[=value][,...]]`` 931 Add device driver. prop=value sets driver properties. Valid 932 properties depend on the driver. To get help on possible drivers and 933 properties, use ``-device help`` and ``-device driver,help``. 934 935 Some drivers are: 936 937``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]`` 938 Add an IPMI BMC. This is a simulation of a hardware management 939 interface processor that normally sits on a system. It provides a 940 watchdog and the ability to reset and power control the system. You 941 need to connect this to an IPMI interface to make it useful 942 943 The IPMI slave address to use for the BMC. The default is 0x20. This 944 address is the BMC's address on the I2C network of management 945 controllers. If you don't know what this means, it is safe to ignore 946 it. 947 948 ``id=id`` 949 The BMC id for interfaces to use this device. 950 951 ``slave_addr=val`` 952 Define slave address to use for the BMC. The default is 0x20. 953 954 ``sdrfile=file`` 955 file containing raw Sensor Data Records (SDR) data. The default 956 is none. 957 958 ``fruareasize=val`` 959 size of a Field Replaceable Unit (FRU) area. The default is 960 1024. 961 962 ``frudatafile=file`` 963 file containing raw Field Replaceable Unit (FRU) inventory data. 964 The default is none. 965 966 ``guid=uuid`` 967 value for the GUID for the BMC, in standard UUID format. If this 968 is set, get "Get GUID" command to the BMC will return it. 969 Otherwise "Get GUID" will return an error. 970 971``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]`` 972 Add a connection to an external IPMI BMC simulator. Instead of 973 locally emulating the BMC like the above item, instead connect to an 974 external entity that provides the IPMI services. 975 976 A connection is made to an external BMC simulator. If you do this, 977 it is strongly recommended that you use the "reconnect=" chardev 978 option to reconnect to the simulator if the connection is lost. Note 979 that if this is not used carefully, it can be a security issue, as 980 the interface has the ability to send resets, NMIs, and power off 981 the VM. It's best if QEMU makes a connection to an external 982 simulator running on a secure port on localhost, so neither the 983 simulator nor QEMU is exposed to any outside network. 984 985 See the "lanserv/README.vm" file in the OpenIPMI library for more 986 details on the external interface. 987 988``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]`` 989 Add a KCS IPMI interafce on the ISA bus. This also adds a 990 corresponding ACPI and SMBIOS entries, if appropriate. 991 992 ``bmc=id`` 993 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern 994 above. 995 996 ``ioport=val`` 997 Define the I/O address of the interface. The default is 0xca0 998 for KCS. 999 1000 ``irq=val`` 1001 Define the interrupt to use. The default is 5. To disable 1002 interrupts, set this to 0. 1003 1004``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]`` 1005 Like the KCS interface, but defines a BT interface. The default port 1006 is 0xe4 and the default interrupt is 5. 1007 1008``-device pci-ipmi-kcs,bmc=id`` 1009 Add a KCS IPMI interafce on the PCI bus. 1010 1011 ``bmc=id`` 1012 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above. 1013 1014``-device pci-ipmi-bt,bmc=id`` 1015 Like the KCS interface, but defines a BT interface on the PCI bus. 1016 1017``-device intel-iommu[,option=...]`` 1018 This is only supported by ``-machine q35``, which will enable Intel VT-d 1019 emulation within the guest. It supports below options: 1020 1021 ``intremap=on|off`` (default: auto) 1022 This enables interrupt remapping feature. It's required to enable 1023 complete x2apic. Currently it only supports kvm kernel-irqchip modes 1024 ``off`` or ``split``, while full kernel-irqchip is not yet supported. 1025 The default value is "auto", which will be decided by the mode of 1026 kernel-irqchip. 1027 1028 ``caching-mode=on|off`` (default: off) 1029 This enables caching mode for the VT-d emulated device. When 1030 caching-mode is enabled, each guest DMA buffer mapping will generate an 1031 IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in 1032 a synchronous way. It is required for ``-device vfio-pci`` to work 1033 with the VT-d device, because host assigned devices requires to setup 1034 the DMA mapping on the host before guest DMA starts. 1035 1036 ``device-iotlb=on|off`` (default: off) 1037 This enables device-iotlb capability for the emulated VT-d device. So 1038 far virtio/vhost should be the only real user for this parameter, 1039 paired with ats=on configured for the device. 1040 1041 ``aw-bits=39|48`` (default: 39) 1042 This decides the address width of IOVA address space. The address 1043 space has 39 bits width for 3-level IOMMU page tables, and 48 bits for 1044 4-level IOMMU page tables. 1045 1046 Please also refer to the wiki page for general scenarios of VT-d 1047 emulation in QEMU: https://wiki.qemu.org/Features/VT-d. 1048 1049ERST 1050 1051DEF("name", HAS_ARG, QEMU_OPTION_name, 1052 "-name string1[,process=string2][,debug-threads=on|off]\n" 1053 " set the name of the guest\n" 1054 " string1 sets the window title and string2 the process name\n" 1055 " When debug-threads is enabled, individual threads are given a separate name\n" 1056 " NOTE: The thread names are for debugging and not a stable API.\n", 1057 QEMU_ARCH_ALL) 1058SRST 1059``-name name`` 1060 Sets the name of the guest. This name will be displayed in the SDL 1061 window caption. The name will also be used for the VNC server. Also 1062 optionally set the top visible process name in Linux. Naming of 1063 individual threads can also be enabled on Linux to aid debugging. 1064ERST 1065 1066DEF("uuid", HAS_ARG, QEMU_OPTION_uuid, 1067 "-uuid %08x-%04x-%04x-%04x-%012x\n" 1068 " specify machine UUID\n", QEMU_ARCH_ALL) 1069SRST 1070``-uuid uuid`` 1071 Set system UUID. 1072ERST 1073 1074DEFHEADING() 1075 1076DEFHEADING(Block device options:) 1077 1078DEF("fda", HAS_ARG, QEMU_OPTION_fda, 1079 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL) 1080DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL) 1081SRST 1082``-fda file`` 1083 \ 1084``-fdb file`` 1085 Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in 1086 the System Emulation Users Guide). 1087ERST 1088 1089DEF("hda", HAS_ARG, QEMU_OPTION_hda, 1090 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL) 1091DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL) 1092DEF("hdc", HAS_ARG, QEMU_OPTION_hdc, 1093 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL) 1094DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL) 1095SRST 1096``-hda file`` 1097 \ 1098``-hdb file`` 1099 \ 1100``-hdc file`` 1101 \ 1102``-hdd file`` 1103 Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images` 1104 chapter in the System Emulation Users Guide). 1105ERST 1106 1107DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom, 1108 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n", 1109 QEMU_ARCH_ALL) 1110SRST 1111``-cdrom file`` 1112 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at 1113 the same time). You can use the host CD-ROM by using ``/dev/cdrom`` 1114 as filename. 1115ERST 1116 1117DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev, 1118 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n" 1119 " [,cache.direct=on|off][,cache.no-flush=on|off]\n" 1120 " [,read-only=on|off][,auto-read-only=on|off]\n" 1121 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n" 1122 " [,driver specific parameters...]\n" 1123 " configure a block backend\n", QEMU_ARCH_ALL) 1124SRST 1125``-blockdev option[,option[,option[,...]]]`` 1126 Define a new block driver node. Some of the options apply to all 1127 block drivers, other options are only accepted for a specific block 1128 driver. See below for a list of generic options and options for the 1129 most common block drivers. 1130 1131 Options that expect a reference to another node (e.g. ``file``) can 1132 be given in two ways. Either you specify the node name of an already 1133 existing node (file=node-name), or you define a new node inline, 1134 adding options for the referenced node after a dot 1135 (file.filename=path,file.aio=native). 1136 1137 A block driver node created with ``-blockdev`` can be used for a 1138 guest device by specifying its node name for the ``drive`` property 1139 in a ``-device`` argument that defines a block device. 1140 1141 ``Valid options for any block driver node:`` 1142 ``driver`` 1143 Specifies the block driver to use for the given node. 1144 1145 ``node-name`` 1146 This defines the name of the block driver node by which it 1147 will be referenced later. The name must be unique, i.e. it 1148 must not match the name of a different block driver node, or 1149 (if you use ``-drive`` as well) the ID of a drive. 1150 1151 If no node name is specified, it is automatically generated. 1152 The generated node name is not intended to be predictable 1153 and changes between QEMU invocations. For the top level, an 1154 explicit node name must be specified. 1155 1156 ``read-only`` 1157 Open the node read-only. Guest write attempts will fail. 1158 1159 Note that some block drivers support only read-only access, 1160 either generally or in certain configurations. In this case, 1161 the default value ``read-only=off`` does not work and the 1162 option must be specified explicitly. 1163 1164 ``auto-read-only`` 1165 If ``auto-read-only=on`` is set, QEMU may fall back to 1166 read-only usage even when ``read-only=off`` is requested, or 1167 even switch between modes as needed, e.g. depending on 1168 whether the image file is writable or whether a writing user 1169 is attached to the node. 1170 1171 ``force-share`` 1172 Override the image locking system of QEMU by forcing the 1173 node to utilize weaker shared access for permissions where 1174 it would normally request exclusive access. When there is 1175 the potential for multiple instances to have the same file 1176 open (whether this invocation of QEMU is the first or the 1177 second instance), both instances must permit shared access 1178 for the second instance to succeed at opening the file. 1179 1180 Enabling ``force-share=on`` requires ``read-only=on``. 1181 1182 ``cache.direct`` 1183 The host page cache can be avoided with ``cache.direct=on``. 1184 This will attempt to do disk IO directly to the guest's 1185 memory. QEMU may still perform an internal copy of the data. 1186 1187 ``cache.no-flush`` 1188 In case you don't care about data integrity over host 1189 failures, you can use ``cache.no-flush=on``. This option 1190 tells QEMU that it never needs to write any data to the disk 1191 but can instead keep things in cache. If anything goes 1192 wrong, like your host losing power, the disk storage getting 1193 disconnected accidentally, etc. your image will most 1194 probably be rendered unusable. 1195 1196 ``discard=discard`` 1197 discard is one of "ignore" (or "off") or "unmap" (or "on") 1198 and controls whether ``discard`` (also known as ``trim`` or 1199 ``unmap``) requests are ignored or passed to the filesystem. 1200 Some machine types may not support discard requests. 1201 1202 ``detect-zeroes=detect-zeroes`` 1203 detect-zeroes is "off", "on" or "unmap" and enables the 1204 automatic conversion of plain zero writes by the OS to 1205 driver specific optimized zero write commands. You may even 1206 choose "unmap" if discard is set to "unmap" to allow a zero 1207 write to be converted to an ``unmap`` operation. 1208 1209 ``Driver-specific options for file`` 1210 This is the protocol-level block driver for accessing regular 1211 files. 1212 1213 ``filename`` 1214 The path to the image file in the local filesystem 1215 1216 ``aio`` 1217 Specifies the AIO backend (threads/native/io_uring, 1218 default: threads) 1219 1220 ``locking`` 1221 Specifies whether the image file is protected with Linux OFD 1222 / POSIX locks. The default is to use the Linux Open File 1223 Descriptor API if available, otherwise no lock is applied. 1224 (auto/on/off, default: auto) 1225 1226 Example: 1227 1228 :: 1229 1230 -blockdev driver=file,node-name=disk,filename=disk.img 1231 1232 ``Driver-specific options for raw`` 1233 This is the image format block driver for raw images. It is 1234 usually stacked on top of a protocol level block driver such as 1235 ``file``. 1236 1237 ``file`` 1238 Reference to or definition of the data source block driver 1239 node (e.g. a ``file`` driver node) 1240 1241 Example 1: 1242 1243 :: 1244 1245 -blockdev driver=file,node-name=disk_file,filename=disk.img 1246 -blockdev driver=raw,node-name=disk,file=disk_file 1247 1248 Example 2: 1249 1250 :: 1251 1252 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img 1253 1254 ``Driver-specific options for qcow2`` 1255 This is the image format block driver for qcow2 images. It is 1256 usually stacked on top of a protocol level block driver such as 1257 ``file``. 1258 1259 ``file`` 1260 Reference to or definition of the data source block driver 1261 node (e.g. a ``file`` driver node) 1262 1263 ``backing`` 1264 Reference to or definition of the backing file block device 1265 (default is taken from the image file). It is allowed to 1266 pass ``null`` here in order to disable the default backing 1267 file. 1268 1269 ``lazy-refcounts`` 1270 Whether to enable the lazy refcounts feature (on/off; 1271 default is taken from the image file) 1272 1273 ``cache-size`` 1274 The maximum total size of the L2 table and refcount block 1275 caches in bytes (default: the sum of l2-cache-size and 1276 refcount-cache-size) 1277 1278 ``l2-cache-size`` 1279 The maximum size of the L2 table cache in bytes (default: if 1280 cache-size is not specified - 32M on Linux platforms, and 8M 1281 on non-Linux platforms; otherwise, as large as possible 1282 within the cache-size, while permitting the requested or the 1283 minimal refcount cache size) 1284 1285 ``refcount-cache-size`` 1286 The maximum size of the refcount block cache in bytes 1287 (default: 4 times the cluster size; or if cache-size is 1288 specified, the part of it which is not used for the L2 1289 cache) 1290 1291 ``cache-clean-interval`` 1292 Clean unused entries in the L2 and refcount caches. The 1293 interval is in seconds. The default value is 600 on 1294 supporting platforms, and 0 on other platforms. Setting it 1295 to 0 disables this feature. 1296 1297 ``pass-discard-request`` 1298 Whether discard requests to the qcow2 device should be 1299 forwarded to the data source (on/off; default: on if 1300 discard=unmap is specified, off otherwise) 1301 1302 ``pass-discard-snapshot`` 1303 Whether discard requests for the data source should be 1304 issued when a snapshot operation (e.g. deleting a snapshot) 1305 frees clusters in the qcow2 file (on/off; default: on) 1306 1307 ``pass-discard-other`` 1308 Whether discard requests for the data source should be 1309 issued on other occasions where a cluster gets freed 1310 (on/off; default: off) 1311 1312 ``overlap-check`` 1313 Which overlap checks to perform for writes to the image 1314 (none/constant/cached/all; default: cached). For details or 1315 finer granularity control refer to the QAPI documentation of 1316 ``blockdev-add``. 1317 1318 Example 1: 1319 1320 :: 1321 1322 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2 1323 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216 1324 1325 Example 2: 1326 1327 :: 1328 1329 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2 1330 1331 ``Driver-specific options for other drivers`` 1332 Please refer to the QAPI documentation of the ``blockdev-add`` 1333 QMP command. 1334ERST 1335 1336DEF("drive", HAS_ARG, QEMU_OPTION_drive, 1337 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" 1338 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" 1339 " [,snapshot=on|off][,rerror=ignore|stop|report]\n" 1340 " [,werror=ignore|stop|report|enospc][,id=name]\n" 1341 " [,aio=threads|native|io_uring]\n" 1342 " [,readonly=on|off][,copy-on-read=on|off]\n" 1343 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n" 1344 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n" 1345 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n" 1346 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n" 1347 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n" 1348 " [[,iops_size=is]]\n" 1349 " [[,group=g]]\n" 1350 " use 'file' as a drive image\n", QEMU_ARCH_ALL) 1351SRST 1352``-drive option[,option[,option[,...]]]`` 1353 Define a new drive. This includes creating a block driver node (the 1354 backend) as well as a guest device, and is mostly a shortcut for 1355 defining the corresponding ``-blockdev`` and ``-device`` options. 1356 1357 ``-drive`` accepts all options that are accepted by ``-blockdev``. 1358 In addition, it knows the following options: 1359 1360 ``file=file`` 1361 This option defines which disk image (see the :ref:`disk images` 1362 chapter in the System Emulation Users Guide) to use with this drive. 1363 If the filename contains comma, you must double it (for instance, 1364 "file=my,,file" to use file "my,file"). 1365 1366 Special files such as iSCSI devices can be specified using 1367 protocol specific URLs. See the section for "Device URL Syntax" 1368 for more information. 1369 1370 ``if=interface`` 1371 This option defines on which type on interface the drive is 1372 connected. Available types are: ide, scsi, sd, mtd, floppy, 1373 pflash, virtio, none. 1374 1375 ``bus=bus,unit=unit`` 1376 These options define where is connected the drive by defining 1377 the bus number and the unit id. 1378 1379 ``index=index`` 1380 This option defines where the drive is connected by using an 1381 index in the list of available connectors of a given interface 1382 type. 1383 1384 ``media=media`` 1385 This option defines the type of the media: disk or cdrom. 1386 1387 ``snapshot=snapshot`` 1388 snapshot is "on" or "off" and controls snapshot mode for the 1389 given drive (see ``-snapshot``). 1390 1391 ``cache=cache`` 1392 cache is "none", "writeback", "unsafe", "directsync" or 1393 "writethrough" and controls how the host cache is used to access 1394 block data. This is a shortcut that sets the ``cache.direct`` 1395 and ``cache.no-flush`` options (as in ``-blockdev``), and 1396 additionally ``cache.writeback``, which provides a default for 1397 the ``write-cache`` option of block guest devices (as in 1398 ``-device``). The modes correspond to the following settings: 1399 1400 ============= =============== ============ ============== 1401 \ cache.writeback cache.direct cache.no-flush 1402 ============= =============== ============ ============== 1403 writeback on off off 1404 none on on off 1405 writethrough off off off 1406 directsync off on off 1407 unsafe on off on 1408 ============= =============== ============ ============== 1409 1410 The default mode is ``cache=writeback``. 1411 1412 ``aio=aio`` 1413 aio is "threads", "native", or "io_uring" and selects between pthread 1414 based disk I/O, native Linux AIO, or Linux io_uring API. 1415 1416 ``format=format`` 1417 Specify which disk format will be used rather than detecting the 1418 format. Can be used to specify format=raw to avoid interpreting 1419 an untrusted format header. 1420 1421 ``werror=action,rerror=action`` 1422 Specify which action to take on write and read errors. Valid 1423 actions are: "ignore" (ignore the error and try to continue), 1424 "stop" (pause QEMU), "report" (report the error to the guest), 1425 "enospc" (pause QEMU only if the host disk is full; report the 1426 error to the guest otherwise). The default setting is 1427 ``werror=enospc`` and ``rerror=report``. 1428 1429 ``copy-on-read=copy-on-read`` 1430 copy-on-read is "on" or "off" and enables whether to copy read 1431 backing file sectors into the image file. 1432 1433 ``bps=b,bps_rd=r,bps_wr=w`` 1434 Specify bandwidth throttling limits in bytes per second, either 1435 for all request types or for reads or writes only. Small values 1436 can lead to timeouts or hangs inside the guest. A safe minimum 1437 for disks is 2 MB/s. 1438 1439 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm`` 1440 Specify bursts in bytes per second, either for all request types 1441 or for reads or writes only. Bursts allow the guest I/O to spike 1442 above the limit temporarily. 1443 1444 ``iops=i,iops_rd=r,iops_wr=w`` 1445 Specify request rate limits in requests per second, either for 1446 all request types or for reads or writes only. 1447 1448 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm`` 1449 Specify bursts in requests per second, either for all request 1450 types or for reads or writes only. Bursts allow the guest I/O to 1451 spike above the limit temporarily. 1452 1453 ``iops_size=is`` 1454 Let every is bytes of a request count as a new request for iops 1455 throttling purposes. Use this option to prevent guests from 1456 circumventing iops limits by sending fewer but larger requests. 1457 1458 ``group=g`` 1459 Join a throttling quota group with given name g. All drives that 1460 are members of the same group are accounted for together. Use 1461 this option to prevent guests from circumventing throttling 1462 limits by using many small disks instead of a single larger 1463 disk. 1464 1465 By default, the ``cache.writeback=on`` mode is used. It will report 1466 data writes as completed as soon as the data is present in the host 1467 page cache. This is safe as long as your guest OS makes sure to 1468 correctly flush disk caches where needed. If your guest OS does not 1469 handle volatile disk write caches correctly and your host crashes or 1470 loses power, then the guest may experience data corruption. 1471 1472 For such guests, you should consider using ``cache.writeback=off``. 1473 This means that the host page cache will be used to read and write 1474 data, but write notification will be sent to the guest only after 1475 QEMU has made sure to flush each write to the disk. Be aware that 1476 this has a major impact on performance. 1477 1478 When using the ``-snapshot`` option, unsafe caching is always used. 1479 1480 Copy-on-read avoids accessing the same backing file sectors 1481 repeatedly and is useful when the backing file is over a slow 1482 network. By default copy-on-read is off. 1483 1484 Instead of ``-cdrom`` you can use: 1485 1486 .. parsed-literal:: 1487 1488 |qemu_system| -drive file=file,index=2,media=cdrom 1489 1490 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use: 1491 1492 .. parsed-literal:: 1493 1494 |qemu_system| -drive file=file,index=0,media=disk 1495 |qemu_system| -drive file=file,index=1,media=disk 1496 |qemu_system| -drive file=file,index=2,media=disk 1497 |qemu_system| -drive file=file,index=3,media=disk 1498 1499 You can open an image using pre-opened file descriptors from an fd 1500 set: 1501 1502 .. parsed-literal:: 1503 1504 |qemu_system| \\ 1505 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 1506 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 1507 -drive file=/dev/fdset/2,index=0,media=disk 1508 1509 You can connect a CDROM to the slave of ide0: 1510 1511 .. parsed-literal:: 1512 1513 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom 1514 1515 If you don't specify the "file=" argument, you define an empty 1516 drive: 1517 1518 .. parsed-literal:: 1519 1520 |qemu_system_x86| -drive if=ide,index=1,media=cdrom 1521 1522 Instead of ``-fda``, ``-fdb``, you can use: 1523 1524 .. parsed-literal:: 1525 1526 |qemu_system_x86| -drive file=file,index=0,if=floppy 1527 |qemu_system_x86| -drive file=file,index=1,if=floppy 1528 1529 By default, interface is "ide" and index is automatically 1530 incremented: 1531 1532 .. parsed-literal:: 1533 1534 |qemu_system_x86| -drive file=a -drive file=b" 1535 1536 is interpreted like: 1537 1538 .. parsed-literal:: 1539 1540 |qemu_system_x86| -hda a -hdb b 1541ERST 1542 1543DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock, 1544 "-mtdblock file use 'file' as on-board Flash memory image\n", 1545 QEMU_ARCH_ALL) 1546SRST 1547``-mtdblock file`` 1548 Use file as on-board Flash memory image. 1549ERST 1550 1551DEF("sd", HAS_ARG, QEMU_OPTION_sd, 1552 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL) 1553SRST 1554``-sd file`` 1555 Use file as SecureDigital card image. 1556ERST 1557 1558DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, 1559 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) 1560SRST 1561``-pflash file`` 1562 Use file as a parallel flash image. 1563ERST 1564 1565DEF("snapshot", 0, QEMU_OPTION_snapshot, 1566 "-snapshot write to temporary files instead of disk image files\n", 1567 QEMU_ARCH_ALL) 1568SRST 1569``-snapshot`` 1570 Write to temporary files instead of disk image files. In this case, 1571 the raw disk image you use is not written back. You can however 1572 force the write back by pressing C-a s (see the :ref:`disk images` 1573 chapter in the System Emulation Users Guide). 1574ERST 1575 1576DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev, 1577 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1578 " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n" 1579 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n" 1580 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n" 1581 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n" 1582 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n" 1583 " [[,throttling.iops-size=is]]\n" 1584 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n" 1585 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n" 1586 "-fsdev synth,id=id\n", 1587 QEMU_ARCH_ALL) 1588 1589SRST 1590``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]`` 1591 \ 1592``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]`` 1593 \ 1594``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]`` 1595 \ 1596``-fsdev synth,id=id[,readonly=on]`` 1597 Define a new file system device. Valid options are: 1598 1599 ``local`` 1600 Accesses to the filesystem are done by QEMU. 1601 1602 ``proxy`` 1603 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1604 1605 ``synth`` 1606 Synthetic filesystem, only used by QTests. 1607 1608 ``id=id`` 1609 Specifies identifier for this device. 1610 1611 ``path=path`` 1612 Specifies the export path for the file system device. Files 1613 under this path will be available to the 9p client on the guest. 1614 1615 ``security_model=security_model`` 1616 Specifies the security model to be used for this export path. 1617 Supported security models are "passthrough", "mapped-xattr", 1618 "mapped-file" and "none". In "passthrough" security model, files 1619 are stored using the same credentials as they are created on the 1620 guest. This requires QEMU to run as root. In "mapped-xattr" 1621 security model, some of the file attributes like uid, gid, mode 1622 bits and link target are stored as file attributes. For 1623 "mapped-file" these attributes are stored in the hidden 1624 .virtfs\_metadata directory. Directories exported by this 1625 security model cannot interact with other unix tools. "none" 1626 security model is same as passthrough except the sever won't 1627 report failures if it fails to set file attributes like 1628 ownership. Security model is mandatory only for local fsdriver. 1629 Other fsdrivers (like proxy) don't take security model as a 1630 parameter. 1631 1632 ``writeout=writeout`` 1633 This is an optional argument. The only supported value is 1634 "immediate". This means that host page cache will be used to 1635 read and write data but write notification will be sent to the 1636 guest only when the data has been reported as written by the 1637 storage subsystem. 1638 1639 ``readonly=on`` 1640 Enables exporting 9p share as a readonly mount for guests. By 1641 default read-write access is given. 1642 1643 ``socket=socket`` 1644 Enables proxy filesystem driver to use passed socket file for 1645 communicating with virtfs-proxy-helper(1). 1646 1647 ``sock_fd=sock_fd`` 1648 Enables proxy filesystem driver to use passed socket descriptor 1649 for communicating with virtfs-proxy-helper(1). Usually a helper 1650 like libvirt will create socketpair and pass one of the fds as 1651 sock\_fd. 1652 1653 ``fmode=fmode`` 1654 Specifies the default mode for newly created files on the host. 1655 Works only with security models "mapped-xattr" and 1656 "mapped-file". 1657 1658 ``dmode=dmode`` 1659 Specifies the default mode for newly created directories on the 1660 host. Works only with security models "mapped-xattr" and 1661 "mapped-file". 1662 1663 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w`` 1664 Specify bandwidth throttling limits in bytes per second, either 1665 for all request types or for reads or writes only. 1666 1667 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm`` 1668 Specify bursts in bytes per second, either for all request types 1669 or for reads or writes only. Bursts allow the guest I/O to spike 1670 above the limit temporarily. 1671 1672 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w`` 1673 Specify request rate limits in requests per second, either for 1674 all request types or for reads or writes only. 1675 1676 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm`` 1677 Specify bursts in requests per second, either for all request 1678 types or for reads or writes only. Bursts allow the guest I/O to 1679 spike above the limit temporarily. 1680 1681 ``throttling.iops-size=is`` 1682 Let every is bytes of a request count as a new request for iops 1683 throttling purposes. 1684 1685 -fsdev option is used along with -device driver "virtio-9p-...". 1686 1687``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag`` 1688 Options for virtio-9p-... driver are: 1689 1690 ``type`` 1691 Specifies the variant to be used. Supported values are "pci", 1692 "ccw" or "device", depending on the machine type. 1693 1694 ``fsdev=id`` 1695 Specifies the id value specified along with -fsdev option. 1696 1697 ``mount_tag=mount_tag`` 1698 Specifies the tag name to be used by the guest to mount this 1699 export point. 1700ERST 1701 1702DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, 1703 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1704 " [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n" 1705 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n" 1706 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n" 1707 "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n", 1708 QEMU_ARCH_ALL) 1709 1710SRST 1711``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]`` 1712 \ 1713``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1714 \ 1715``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1716 \ 1717``-virtfs synth,mount_tag=mount_tag`` 1718 Define a new virtual filesystem device and expose it to the guest using 1719 a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain 1720 directory on host is made directly accessible by guest as a pass-through 1721 file system by using the 9P network protocol for communication between 1722 host and guests, if desired even accessible, shared by several guests 1723 simultaniously. 1724 1725 Note that ``-virtfs`` is actually just a convenience shortcut for its 1726 generalized form ``-fsdev -device virtio-9p-pci``. 1727 1728 The general form of pass-through file system options are: 1729 1730 ``local`` 1731 Accesses to the filesystem are done by QEMU. 1732 1733 ``proxy`` 1734 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1735 1736 ``synth`` 1737 Synthetic filesystem, only used by QTests. 1738 1739 ``id=id`` 1740 Specifies identifier for the filesystem device 1741 1742 ``path=path`` 1743 Specifies the export path for the file system device. Files 1744 under this path will be available to the 9p client on the guest. 1745 1746 ``security_model=security_model`` 1747 Specifies the security model to be used for this export path. 1748 Supported security models are "passthrough", "mapped-xattr", 1749 "mapped-file" and "none". In "passthrough" security model, files 1750 are stored using the same credentials as they are created on the 1751 guest. This requires QEMU to run as root. In "mapped-xattr" 1752 security model, some of the file attributes like uid, gid, mode 1753 bits and link target are stored as file attributes. For 1754 "mapped-file" these attributes are stored in the hidden 1755 .virtfs\_metadata directory. Directories exported by this 1756 security model cannot interact with other unix tools. "none" 1757 security model is same as passthrough except the sever won't 1758 report failures if it fails to set file attributes like 1759 ownership. Security model is mandatory only for local fsdriver. 1760 Other fsdrivers (like proxy) don't take security model as a 1761 parameter. 1762 1763 ``writeout=writeout`` 1764 This is an optional argument. The only supported value is 1765 "immediate". This means that host page cache will be used to 1766 read and write data but write notification will be sent to the 1767 guest only when the data has been reported as written by the 1768 storage subsystem. 1769 1770 ``readonly=on`` 1771 Enables exporting 9p share as a readonly mount for guests. By 1772 default read-write access is given. 1773 1774 ``socket=socket`` 1775 Enables proxy filesystem driver to use passed socket file for 1776 communicating with virtfs-proxy-helper(1). Usually a helper like 1777 libvirt will create socketpair and pass one of the fds as 1778 sock\_fd. 1779 1780 ``sock_fd`` 1781 Enables proxy filesystem driver to use passed 'sock\_fd' as the 1782 socket descriptor for interfacing with virtfs-proxy-helper(1). 1783 1784 ``fmode=fmode`` 1785 Specifies the default mode for newly created files on the host. 1786 Works only with security models "mapped-xattr" and 1787 "mapped-file". 1788 1789 ``dmode=dmode`` 1790 Specifies the default mode for newly created directories on the 1791 host. Works only with security models "mapped-xattr" and 1792 "mapped-file". 1793 1794 ``mount_tag=mount_tag`` 1795 Specifies the tag name to be used by the guest to mount this 1796 export point. 1797 1798 ``multidevs=multidevs`` 1799 Specifies how to deal with multiple devices being shared with a 1800 9p export. Supported behaviours are either "remap", "forbid" or 1801 "warn". The latter is the default behaviour on which virtfs 9p 1802 expects only one device to be shared with the same export, and 1803 if more than one device is shared and accessed via the same 9p 1804 export then only a warning message is logged (once) by qemu on 1805 host side. In order to avoid file ID collisions on guest you 1806 should either create a separate virtfs export for each device to 1807 be shared with guests (recommended way) or you might use "remap" 1808 instead which allows you to share multiple devices with only one 1809 export instead, which is achieved by remapping the original 1810 inode numbers from host to guest in a way that would prevent 1811 such collisions. Remapping inodes in such use cases is required 1812 because the original device IDs from host are never passed and 1813 exposed on guest. Instead all files of an export shared with 1814 virtfs always share the same device id on guest. So two files 1815 with identical inode numbers but from actually different devices 1816 on host would otherwise cause a file ID collision and hence 1817 potential misbehaviours on guest. "forbid" on the other hand 1818 assumes like "warn" that only one device is shared by the same 1819 export, however it will not only log a warning message but also 1820 deny access to additional devices on guest. Note though that 1821 "forbid" does currently not block all possible file access 1822 operations (e.g. readdir() would still return entries from other 1823 devices). 1824ERST 1825 1826DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi, 1827 "-iscsi [user=user][,password=password]\n" 1828 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n" 1829 " [,initiator-name=initiator-iqn][,id=target-iqn]\n" 1830 " [,timeout=timeout]\n" 1831 " iSCSI session parameters\n", QEMU_ARCH_ALL) 1832 1833SRST 1834``-iscsi`` 1835 Configure iSCSI session parameters. 1836ERST 1837 1838DEFHEADING() 1839 1840DEFHEADING(USB convenience options:) 1841 1842DEF("usb", 0, QEMU_OPTION_usb, 1843 "-usb enable on-board USB host controller (if not enabled by default)\n", 1844 QEMU_ARCH_ALL) 1845SRST 1846``-usb`` 1847 Enable USB emulation on machine types with an on-board USB host 1848 controller (if not enabled by default). Note that on-board USB host 1849 controllers may not support USB 3.0. In this case 1850 ``-device qemu-xhci`` can be used instead on machines with PCI. 1851ERST 1852 1853DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice, 1854 "-usbdevice name add the host or guest USB device 'name'\n", 1855 QEMU_ARCH_ALL) 1856SRST 1857``-usbdevice devname`` 1858 Add the USB device devname, and enable an on-board USB controller 1859 if possible and necessary (just like it can be done via 1860 ``-machine usb=on``). Note that this option is mainly intended for 1861 the user's convenience only. More fine-grained control can be 1862 achieved by selecting a USB host controller (if necessary) and the 1863 desired USB device via the ``-device`` option instead. For example, 1864 instead of using ``-usbdevice mouse`` it is possible to use 1865 ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse 1866 to a USB 3.0 controller instead (at least on machines that support 1867 PCI and do not have an USB controller enabled by default yet). 1868 For more details, see the chapter about 1869 :ref:`Connecting USB devices` in the System Emulation Users Guide. 1870 Possible devices for devname are: 1871 1872 ``braille`` 1873 Braille device. This will use BrlAPI to display the braille 1874 output on a real or fake device (i.e. it also creates a 1875 corresponding ``braille`` chardev automatically beside the 1876 ``usb-braille`` USB device). 1877 1878 ``keyboard`` 1879 Standard USB keyboard. Will override the PS/2 keyboard (if present). 1880 1881 ``mouse`` 1882 Virtual Mouse. This will override the PS/2 mouse emulation when 1883 activated. 1884 1885 ``tablet`` 1886 Pointer device that uses absolute coordinates (like a 1887 touchscreen). This means QEMU is able to report the mouse 1888 position without having to grab the mouse. Also overrides the 1889 PS/2 mouse emulation when activated. 1890 1891 ``wacom-tablet`` 1892 Wacom PenPartner USB tablet. 1893 1894 1895ERST 1896 1897DEFHEADING() 1898 1899DEFHEADING(Display options:) 1900 1901DEF("display", HAS_ARG, QEMU_OPTION_display, 1902#if defined(CONFIG_SPICE) 1903 "-display spice-app[,gl=on|off]\n" 1904#endif 1905#if defined(CONFIG_SDL) 1906 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off][,gl=on|core|es|off]\n" 1907 " [,grab-mod=<mod>][,show-cursor=on|off][,window-close=on|off]\n" 1908#endif 1909#if defined(CONFIG_GTK) 1910 "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n" 1911 " [,show-cursor=on|off][,window-close=on|off]\n" 1912#endif 1913#if defined(CONFIG_VNC) 1914 "-display vnc=<display>[,<optargs>]\n" 1915#endif 1916#if defined(CONFIG_CURSES) 1917 "-display curses[,charset=<encoding>]\n" 1918#endif 1919#if defined(CONFIG_COCOA) 1920 "-display cocoa[,full-grab=on|off][,swap-opt-cmd=on|off]\n" 1921#endif 1922#if defined(CONFIG_OPENGL) 1923 "-display egl-headless[,rendernode=<file>]\n" 1924#endif 1925#if defined(CONFIG_DBUS_DISPLAY) 1926 "-display dbus[,addr=<dbusaddr>]\n" 1927 " [,gl=on|core|es|off][,rendernode=<file>]\n" 1928#endif 1929#if defined(CONFIG_COCOA) 1930 "-display cocoa[,show-cursor=on|off][,left-command-key=on|off]\n" 1931#endif 1932 "-display none\n" 1933 " select display backend type\n" 1934 " The default display is equivalent to\n " 1935#if defined(CONFIG_GTK) 1936 "\"-display gtk\"\n" 1937#elif defined(CONFIG_SDL) 1938 "\"-display sdl\"\n" 1939#elif defined(CONFIG_COCOA) 1940 "\"-display cocoa\"\n" 1941#elif defined(CONFIG_VNC) 1942 "\"-vnc localhost:0,to=99,id=default\"\n" 1943#else 1944 "\"-display none\"\n" 1945#endif 1946 , QEMU_ARCH_ALL) 1947SRST 1948``-display type`` 1949 Select type of display to use. This option is a replacement for the 1950 old style -sdl/-curses/... options. Use ``-display help`` to list 1951 the available display types. Valid values for type are 1952 1953 ``spice-app[,gl=on|off]`` 1954 Start QEMU as a Spice server and launch the default Spice client 1955 application. The Spice server will redirect the serial consoles 1956 and QEMU monitors. (Since 4.0) 1957 1958 ``dbus`` 1959 Export the display over D-Bus interfaces. (Since 7.0) 1960 1961 The connection is registered with the "org.qemu" name (and queued when 1962 already owned). 1963 1964 ``addr=<dbusaddr>`` : D-Bus bus address to connect to. 1965 1966 ``p2p=yes|no`` : Use peer-to-peer connection, accepted via QMP ``add_client``. 1967 1968 ``gl=on|off|core|es`` : Use OpenGL for rendering (the D-Bus interface 1969 will share framebuffers with DMABUF file descriptors). 1970 1971 ``sdl`` 1972 Display video output via SDL (usually in a separate graphics 1973 window; see the SDL documentation for other possibilities). 1974 Valid parameters are: 1975 1976 ``grab-mod=<mods>`` : Used to select the modifier keys for toggling 1977 the mouse grabbing in conjunction with the "g" key. ``<mods>`` can be 1978 either ``lshift-lctrl-lalt`` or ``rctrl``. 1979 1980 ``alt_grab=on|off`` : Use Control+Alt+Shift-g to toggle mouse grabbing. 1981 This parameter is deprecated - use ``grab-mod`` instead. 1982 1983 ``ctrl_grab=on|off`` : Use Right-Control-g to toggle mouse grabbing. 1984 This parameter is deprecated - use ``grab-mod`` instead. 1985 1986 ``gl=on|off|core|es`` : Use OpenGL for displaying 1987 1988 ``show-cursor=on|off`` : Force showing the mouse cursor 1989 1990 ``window-close=on|off`` : Allow to quit qemu with window close button 1991 1992 ``gtk`` 1993 Display video output in a GTK window. This interface provides 1994 drop-down menus and other UI elements to configure and control 1995 the VM during runtime. Valid parameters are: 1996 1997 ``full-screen=on|off`` : Start in fullscreen mode 1998 1999 ``gl=on|off`` : Use OpenGL for displaying 2000 2001 ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover 2002 2003 ``show-cursor=on|off`` : Force showing the mouse cursor 2004 2005 ``window-close=on|off`` : Allow to quit qemu with window close button 2006 2007 ``curses[,charset=<encoding>]`` 2008 Display video output via curses. For graphics device models 2009 which support a text mode, QEMU can display this output using a 2010 curses/ncurses interface. Nothing is displayed when the graphics 2011 device is in graphical mode or if the graphics device does not 2012 support a text mode. Generally only the VGA device models 2013 support text mode. The font charset used by the guest can be 2014 specified with the ``charset`` option, for example 2015 ``charset=CP850`` for IBM CP850 encoding. The default is 2016 ``CP437``. 2017 2018 ``cocoa`` 2019 Display video output in a Cocoa window. Mac only. This interface 2020 provides drop-down menus and other UI elements to configure and 2021 control the VM during runtime. Valid parameters are: 2022 2023 ``show-cursor=on|off`` : Force showing the mouse cursor 2024 2025 ``left-command-key=on|off`` : Disable forwarding left command key to host 2026 2027 ``egl-headless[,rendernode=<file>]`` 2028 Offload all OpenGL operations to a local DRI device. For any 2029 graphical display, this display needs to be paired with either 2030 VNC or SPICE displays. 2031 2032 ``vnc=<display>`` 2033 Start a VNC server on display <display> 2034 2035 ``none`` 2036 Do not display video output. The guest will still see an 2037 emulated graphics card, but its output will not be displayed to 2038 the QEMU user. This option differs from the -nographic option in 2039 that it only affects what is done with video output; -nographic 2040 also changes the destination of the serial and parallel port 2041 data. 2042ERST 2043 2044DEF("nographic", 0, QEMU_OPTION_nographic, 2045 "-nographic disable graphical output and redirect serial I/Os to console\n", 2046 QEMU_ARCH_ALL) 2047SRST 2048``-nographic`` 2049 Normally, if QEMU is compiled with graphical window support, it 2050 displays output such as guest graphics, guest console, and the QEMU 2051 monitor in a window. With this option, you can totally disable 2052 graphical output so that QEMU is a simple command line application. 2053 The emulated serial port is redirected on the console and muxed with 2054 the monitor (unless redirected elsewhere explicitly). Therefore, you 2055 can still use QEMU to debug a Linux kernel with a serial console. 2056 Use C-a h for help on switching between the console and monitor. 2057ERST 2058 2059DEF("curses", 0, QEMU_OPTION_curses, 2060 "-curses shorthand for -display curses\n", 2061 QEMU_ARCH_ALL) 2062SRST 2063``-curses`` 2064 Normally, if QEMU is compiled with graphical window support, it 2065 displays output such as guest graphics, guest console, and the QEMU 2066 monitor in a window. With this option, QEMU can display the VGA 2067 output when in text mode using a curses/ncurses interface. Nothing 2068 is displayed in graphical mode. 2069ERST 2070 2071DEF("alt-grab", 0, QEMU_OPTION_alt_grab, 2072 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n", 2073 QEMU_ARCH_ALL) 2074SRST 2075``-alt-grab`` 2076 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that 2077 this also affects the special keys (for fullscreen, monitor-mode 2078 switching, etc). This option is deprecated - please use 2079 ``-display sdl,grab-mod=lshift-lctrl-lalt`` instead. 2080ERST 2081 2082DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab, 2083 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n", 2084 QEMU_ARCH_ALL) 2085SRST 2086``-ctrl-grab`` 2087 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this 2088 also affects the special keys (for fullscreen, monitor-mode 2089 switching, etc). This option is deprecated - please use 2090 ``-display sdl,grab-mod=rctrl`` instead. 2091ERST 2092 2093DEF("sdl", 0, QEMU_OPTION_sdl, 2094 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL) 2095SRST 2096``-sdl`` 2097 Enable SDL. 2098ERST 2099 2100#ifdef CONFIG_SPICE 2101DEF("spice", HAS_ARG, QEMU_OPTION_spice, 2102 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n" 2103 " [,x509-key-file=<file>][,x509-key-password=<file>]\n" 2104 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n" 2105 " [,x509-dh-key-file=<file>][,addr=addr]\n" 2106 " [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n" 2107 " [,tls-ciphers=<list>]\n" 2108 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n" 2109 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n" 2110 " [,sasl=on|off][,disable-ticketing=on|off]\n" 2111 " [,password=<string>][,password-secret=<secret-id>]\n" 2112 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n" 2113 " [,jpeg-wan-compression=[auto|never|always]]\n" 2114 " [,zlib-glz-wan-compression=[auto|never|always]]\n" 2115 " [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n" 2116 " [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n" 2117 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n" 2118 " [,gl=[on|off]][,rendernode=<file>]\n" 2119 " enable spice\n" 2120 " at least one of {port, tls-port} is mandatory\n", 2121 QEMU_ARCH_ALL) 2122#endif 2123SRST 2124``-spice option[,option[,...]]`` 2125 Enable the spice remote desktop protocol. Valid options are 2126 2127 ``port=<nr>`` 2128 Set the TCP port spice is listening on for plaintext channels. 2129 2130 ``addr=<addr>`` 2131 Set the IP address spice is listening on. Default is any 2132 address. 2133 2134 ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off`` 2135 Force using the specified IP version. 2136 2137 ``password=<string>`` 2138 Set the password you need to authenticate. 2139 2140 This option is deprecated and insecure because it leaves the 2141 password visible in the process listing. Use ``password-secret`` 2142 instead. 2143 2144 ``password-secret=<secret-id>`` 2145 Set the ID of the ``secret`` object containing the password 2146 you need to authenticate. 2147 2148 ``sasl=on|off`` 2149 Require that the client use SASL to authenticate with the spice. 2150 The exact choice of authentication method used is controlled 2151 from the system / user's SASL configuration file for the 'qemu' 2152 service. This is typically found in /etc/sasl2/qemu.conf. If 2153 running QEMU as an unprivileged user, an environment variable 2154 SASL\_CONF\_PATH can be used to make it search alternate 2155 locations for the service config. While some SASL auth methods 2156 can also provide data encryption (eg GSSAPI), it is recommended 2157 that SASL always be combined with the 'tls' and 'x509' settings 2158 to enable use of SSL and server certificates. This ensures a 2159 data encryption preventing compromise of authentication 2160 credentials. 2161 2162 ``disable-ticketing=on|off`` 2163 Allow client connects without authentication. 2164 2165 ``disable-copy-paste=on|off`` 2166 Disable copy paste between the client and the guest. 2167 2168 ``disable-agent-file-xfer=on|off`` 2169 Disable spice-vdagent based file-xfer between the client and the 2170 guest. 2171 2172 ``tls-port=<nr>`` 2173 Set the TCP port spice is listening on for encrypted channels. 2174 2175 ``x509-dir=<dir>`` 2176 Set the x509 file directory. Expects same filenames as -vnc 2177 $display,x509=$dir 2178 2179 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>`` 2180 The x509 file names can also be configured individually. 2181 2182 ``tls-ciphers=<list>`` 2183 Specify which ciphers to use. 2184 2185 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]`` 2186 Force specific channel to be used with or without TLS 2187 encryption. The options can be specified multiple times to 2188 configure multiple channels. The special name "default" can be 2189 used to set the default mode. For channels which are not 2190 explicitly forced into one mode the spice client is allowed to 2191 pick tls/plaintext as he pleases. 2192 2193 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]`` 2194 Configure image compression (lossless). Default is auto\_glz. 2195 2196 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]`` 2197 Configure wan image compression (lossy for slow links). Default 2198 is auto. 2199 2200 ``streaming-video=[off|all|filter]`` 2201 Configure video stream detection. Default is off. 2202 2203 ``agent-mouse=[on|off]`` 2204 Enable/disable passing mouse events via vdagent. Default is on. 2205 2206 ``playback-compression=[on|off]`` 2207 Enable/disable audio stream compression (using celt 0.5.1). 2208 Default is on. 2209 2210 ``seamless-migration=[on|off]`` 2211 Enable/disable spice seamless migration. Default is off. 2212 2213 ``gl=[on|off]`` 2214 Enable/disable OpenGL context. Default is off. 2215 2216 ``rendernode=<file>`` 2217 DRM render node for OpenGL rendering. If not specified, it will 2218 pick the first available. (Since 2.9) 2219ERST 2220 2221DEF("portrait", 0, QEMU_OPTION_portrait, 2222 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n", 2223 QEMU_ARCH_ALL) 2224SRST 2225``-portrait`` 2226 Rotate graphical output 90 deg left (only PXA LCD). 2227ERST 2228 2229DEF("rotate", HAS_ARG, QEMU_OPTION_rotate, 2230 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n", 2231 QEMU_ARCH_ALL) 2232SRST 2233``-rotate deg`` 2234 Rotate graphical output some deg left (only PXA LCD). 2235ERST 2236 2237DEF("vga", HAS_ARG, QEMU_OPTION_vga, 2238 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n" 2239 " select video card type\n", QEMU_ARCH_ALL) 2240SRST 2241``-vga type`` 2242 Select type of VGA card to emulate. Valid values for type are 2243 2244 ``cirrus`` 2245 Cirrus Logic GD5446 Video card. All Windows versions starting 2246 from Windows 95 should recognize and use this graphic card. For 2247 optimal performances, use 16 bit color depth in the guest and 2248 the host OS. (This card was the default before QEMU 2.2) 2249 2250 ``std`` 2251 Standard VGA card with Bochs VBE extensions. If your guest OS 2252 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if 2253 you want to use high resolution modes (>= 1280x1024x16) then you 2254 should use this option. (This card is the default since QEMU 2255 2.2) 2256 2257 ``vmware`` 2258 VMWare SVGA-II compatible adapter. Use it if you have 2259 sufficiently recent XFree86/XOrg server or Windows guest with a 2260 driver for this card. 2261 2262 ``qxl`` 2263 QXL paravirtual graphic card. It is VGA compatible (including 2264 VESA 2.0 VBE support). Works best with qxl guest drivers 2265 installed though. Recommended choice when using the spice 2266 protocol. 2267 2268 ``tcx`` 2269 (sun4m only) Sun TCX framebuffer. This is the default 2270 framebuffer for sun4m machines and offers both 8-bit and 24-bit 2271 colour depths at a fixed resolution of 1024x768. 2272 2273 ``cg3`` 2274 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit 2275 framebuffer for sun4m machines available in both 1024x768 2276 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people 2277 wishing to run older Solaris versions. 2278 2279 ``virtio`` 2280 Virtio VGA card. 2281 2282 ``none`` 2283 Disable VGA card. 2284ERST 2285 2286DEF("full-screen", 0, QEMU_OPTION_full_screen, 2287 "-full-screen start in full screen\n", QEMU_ARCH_ALL) 2288SRST 2289``-full-screen`` 2290 Start in full screen. 2291ERST 2292 2293DEF("g", HAS_ARG, QEMU_OPTION_g , 2294 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n", 2295 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K) 2296SRST 2297``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]`` 2298 Set the initial graphical resolution and depth (PPC, SPARC only). 2299 2300 For PPC the default is 800x600x32. 2301 2302 For SPARC with the TCX graphics device, the default is 1024x768x8 2303 with the option of 1024x768x24. For cgthree, the default is 2304 1024x768x8 with the option of 1152x900x8 for people who wish to use 2305 OBP. 2306ERST 2307 2308DEF("vnc", HAS_ARG, QEMU_OPTION_vnc , 2309 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL) 2310SRST 2311``-vnc display[,option[,option[,...]]]`` 2312 Normally, if QEMU is compiled with graphical window support, it 2313 displays output such as guest graphics, guest console, and the QEMU 2314 monitor in a window. With this option, you can have QEMU listen on 2315 VNC display display and redirect the VGA display over the VNC 2316 session. It is very useful to enable the usb tablet device when 2317 using this option (option ``-device usb-tablet``). When using the 2318 VNC display, you must use the ``-k`` parameter to set the keyboard 2319 layout if you are not using en-us. Valid syntax for the display is 2320 2321 ``to=L`` 2322 With this option, QEMU will try next available VNC displays, 2323 until the number L, if the origianlly defined "-vnc display" is 2324 not available, e.g. port 5900+display is already used by another 2325 application. By default, to=0. 2326 2327 ``host:d`` 2328 TCP connections will only be allowed from host on display d. By 2329 convention the TCP port is 5900+d. Optionally, host can be 2330 omitted in which case the server will accept connections from 2331 any host. 2332 2333 ``unix:path`` 2334 Connections will be allowed over UNIX domain sockets where path 2335 is the location of a unix socket to listen for connections on. 2336 2337 ``none`` 2338 VNC is initialized but not started. The monitor ``change`` 2339 command can be used to later start the VNC server. 2340 2341 Following the display value there may be one or more option flags 2342 separated by commas. Valid options are 2343 2344 ``reverse=on|off`` 2345 Connect to a listening VNC client via a "reverse" connection. 2346 The client is specified by the display. For reverse network 2347 connections (host:d,``reverse``), the d argument is a TCP port 2348 number, not a display number. 2349 2350 ``websocket=on|off`` 2351 Opens an additional TCP listening port dedicated to VNC 2352 Websocket connections. If a bare websocket option is given, the 2353 Websocket port is 5700+display. An alternative port can be 2354 specified with the syntax ``websocket``\ =port. 2355 2356 If host is specified connections will only be allowed from this 2357 host. It is possible to control the websocket listen address 2358 independently, using the syntax ``websocket``\ =host:port. 2359 2360 If no TLS credentials are provided, the websocket connection 2361 runs in unencrypted mode. If TLS credentials are provided, the 2362 websocket connection requires encrypted client connections. 2363 2364 ``password=on|off`` 2365 Require that password based authentication is used for client 2366 connections. 2367 2368 The password must be set separately using the ``set_password`` 2369 command in the :ref:`QEMU monitor`. The 2370 syntax to change your password is: 2371 ``set_password <protocol> <password>`` where <protocol> could be 2372 either "vnc" or "spice". 2373 2374 If you would like to change <protocol> password expiration, you 2375 should use ``expire_password <protocol> <expiration-time>`` 2376 where expiration time could be one of the following options: 2377 now, never, +seconds or UNIX time of expiration, e.g. +60 to 2378 make password expire in 60 seconds, or 1335196800 to make 2379 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for 2380 this date and time). 2381 2382 You can also use keywords "now" or "never" for the expiration 2383 time to allow <protocol> password to expire immediately or never 2384 expire. 2385 2386 ``password-secret=<secret-id>`` 2387 Require that password based authentication is used for client 2388 connections, using the password provided by the ``secret`` 2389 object identified by ``secret-id``. 2390 2391 ``tls-creds=ID`` 2392 Provides the ID of a set of TLS credentials to use to secure the 2393 VNC server. They will apply to both the normal VNC server socket 2394 and the websocket socket (if enabled). Setting TLS credentials 2395 will cause the VNC server socket to enable the VeNCrypt auth 2396 mechanism. The credentials should have been previously created 2397 using the ``-object tls-creds`` argument. 2398 2399 ``tls-authz=ID`` 2400 Provides the ID of the QAuthZ authorization object against which 2401 the client's x509 distinguished name will validated. This object 2402 is only resolved at time of use, so can be deleted and recreated 2403 on the fly while the VNC server is active. If missing, it will 2404 default to denying access. 2405 2406 ``sasl=on|off`` 2407 Require that the client use SASL to authenticate with the VNC 2408 server. The exact choice of authentication method used is 2409 controlled from the system / user's SASL configuration file for 2410 the 'qemu' service. This is typically found in 2411 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, 2412 an environment variable SASL\_CONF\_PATH can be used to make it 2413 search alternate locations for the service config. While some 2414 SASL auth methods can also provide data encryption (eg GSSAPI), 2415 it is recommended that SASL always be combined with the 'tls' 2416 and 'x509' settings to enable use of SSL and server 2417 certificates. This ensures a data encryption preventing 2418 compromise of authentication credentials. See the 2419 :ref:`VNC security` section in the System Emulation Users Guide 2420 for details on using SASL authentication. 2421 2422 ``sasl-authz=ID`` 2423 Provides the ID of the QAuthZ authorization object against which 2424 the client's SASL username will validated. This object is only 2425 resolved at time of use, so can be deleted and recreated on the 2426 fly while the VNC server is active. If missing, it will default 2427 to denying access. 2428 2429 ``acl=on|off`` 2430 Legacy method for enabling authorization of clients against the 2431 x509 distinguished name and SASL username. It results in the 2432 creation of two ``authz-list`` objects with IDs of 2433 ``vnc.username`` and ``vnc.x509dname``. The rules for these 2434 objects must be configured with the HMP ACL commands. 2435 2436 This option is deprecated and should no longer be used. The new 2437 ``sasl-authz`` and ``tls-authz`` options are a replacement. 2438 2439 ``lossy=on|off`` 2440 Enable lossy compression methods (gradient, JPEG, ...). If this 2441 option is set, VNC client may receive lossy framebuffer updates 2442 depending on its encoding settings. Enabling this option can 2443 save a lot of bandwidth at the expense of quality. 2444 2445 ``non-adaptive=on|off`` 2446 Disable adaptive encodings. Adaptive encodings are enabled by 2447 default. An adaptive encoding will try to detect frequently 2448 updated screen regions, and send updates in these regions using 2449 a lossy encoding (like JPEG). This can be really helpful to save 2450 bandwidth when playing videos. Disabling adaptive encodings 2451 restores the original static behavior of encodings like Tight. 2452 2453 ``share=[allow-exclusive|force-shared|ignore]`` 2454 Set display sharing policy. 'allow-exclusive' allows clients to 2455 ask for exclusive access. As suggested by the rfb spec this is 2456 implemented by dropping other connections. Connecting multiple 2457 clients in parallel requires all clients asking for a shared 2458 session (vncviewer: -shared switch). This is the default. 2459 'force-shared' disables exclusive client access. Useful for 2460 shared desktop sessions, where you don't want someone forgetting 2461 specify -shared disconnect everybody else. 'ignore' completely 2462 ignores the shared flag and allows everybody connect 2463 unconditionally. Doesn't conform to the rfb spec but is 2464 traditional QEMU behavior. 2465 2466 ``key-delay-ms`` 2467 Set keyboard delay, for key down and key up events, in 2468 milliseconds. Default is 10. Keyboards are low-bandwidth 2469 devices, so this slowdown can help the device and guest to keep 2470 up and not lose events in case events are arriving in bulk. 2471 Possible causes for the latter are flaky network connections, or 2472 scripts for automated testing. 2473 2474 ``audiodev=audiodev`` 2475 Use the specified audiodev when the VNC client requests audio 2476 transmission. When not using an -audiodev argument, this option 2477 must be omitted, otherwise is must be present and specify a 2478 valid audiodev. 2479 2480 ``power-control=on|off`` 2481 Permit the remote client to issue shutdown, reboot or reset power 2482 control requests. 2483ERST 2484 2485ARCHHEADING(, QEMU_ARCH_I386) 2486 2487ARCHHEADING(i386 target only:, QEMU_ARCH_I386) 2488 2489DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack, 2490 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n", 2491 QEMU_ARCH_I386) 2492SRST 2493``-win2k-hack`` 2494 Use it when installing Windows 2000 to avoid a disk full bug. After 2495 Windows 2000 is installed, you no longer need this option (this 2496 option slows down the IDE transfers). 2497ERST 2498 2499DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk, 2500 "-no-fd-bootchk disable boot signature checking for floppy disks\n", 2501 QEMU_ARCH_I386) 2502SRST 2503``-no-fd-bootchk`` 2504 Disable boot signature checking for floppy disks in BIOS. May be 2505 needed to boot from old floppy disks. 2506ERST 2507 2508DEF("no-acpi", 0, QEMU_OPTION_no_acpi, 2509 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2510SRST 2511``-no-acpi`` 2512 Disable ACPI (Advanced Configuration and Power Interface) support. 2513 Use it if your guest OS complains about ACPI problems (PC target 2514 machine only). 2515ERST 2516 2517DEF("no-hpet", 0, QEMU_OPTION_no_hpet, 2518 "-no-hpet disable HPET\n", QEMU_ARCH_I386) 2519SRST 2520``-no-hpet`` 2521 Disable HPET support. 2522ERST 2523 2524DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable, 2525 "-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" 2526 " ACPI table description\n", QEMU_ARCH_I386) 2527SRST 2528``-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]...]`` 2529 Add ACPI table with specified header fields and context from 2530 specified files. For file=, take whole ACPI table from the specified 2531 files, including all ACPI headers (possible overridden by other 2532 options). For data=, only data portion of the table is used, all 2533 header information is specified in the command line. If a SLIC table 2534 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id 2535 fields will override the same in the RSDT and the FADT (a.k.a. 2536 FACP), in order to ensure the field matches required by the 2537 Microsoft SLIC spec and the ACPI spec. 2538ERST 2539 2540DEF("smbios", HAS_ARG, QEMU_OPTION_smbios, 2541 "-smbios file=binary\n" 2542 " load SMBIOS entry from binary file\n" 2543 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n" 2544 " [,uefi=on|off]\n" 2545 " specify SMBIOS type 0 fields\n" 2546 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2547 " [,uuid=uuid][,sku=str][,family=str]\n" 2548 " specify SMBIOS type 1 fields\n" 2549 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2550 " [,asset=str][,location=str]\n" 2551 " specify SMBIOS type 2 fields\n" 2552 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n" 2553 " [,sku=str]\n" 2554 " specify SMBIOS type 3 fields\n" 2555 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n" 2556 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n" 2557 " [,processor-id=%d]\n" 2558 " specify SMBIOS type 4 fields\n" 2559 "-smbios type=11[,value=str][,path=filename]\n" 2560 " specify SMBIOS type 11 fields\n" 2561 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n" 2562 " [,asset=str][,part=str][,speed=%d]\n" 2563 " specify SMBIOS type 17 fields\n" 2564 "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n" 2565 " specify SMBIOS type 41 fields\n", 2566 QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2567SRST 2568``-smbios file=binary`` 2569 Load SMBIOS entry from binary file. 2570 2571``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]`` 2572 Specify SMBIOS type 0 fields 2573 2574``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]`` 2575 Specify SMBIOS type 1 fields 2576 2577``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]`` 2578 Specify SMBIOS type 2 fields 2579 2580``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]`` 2581 Specify SMBIOS type 3 fields 2582 2583``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str][,processor-id=%d]`` 2584 Specify SMBIOS type 4 fields 2585 2586``-smbios type=11[,value=str][,path=filename]`` 2587 Specify SMBIOS type 11 fields 2588 2589 This argument can be repeated multiple times, and values are added in the order they are parsed. 2590 Applications intending to use OEM strings data are encouraged to use their application name as 2591 a prefix for the value string. This facilitates passing information for multiple applications 2592 concurrently. 2593 2594 The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax 2595 loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes. 2596 2597 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to 2598 the SMBIOS table in the order in which they appear. 2599 2600 Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535 2601 bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the 2602 guest. Instead it should be used as a indicator to inform the guest where to locate the real 2603 data set, for example, by specifying the serial ID of a block device. 2604 2605 An example passing three strings is 2606 2607 .. parsed-literal:: 2608 2609 -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\ 2610 value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\ 2611 path=/some/file/with/oemstringsdata.txt 2612 2613 In the guest OS this is visible with the ``dmidecode`` command 2614 2615 .. parsed-literal:: 2616 2617 $ dmidecode -t 11 2618 Handle 0x0E00, DMI type 11, 5 bytes 2619 OEM Strings 2620 String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/ 2621 String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os 2622 String 3: myapp:some extra data 2623 2624 2625``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]`` 2626 Specify SMBIOS type 17 fields 2627 2628``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]`` 2629 Specify SMBIOS type 41 fields 2630 2631 This argument can be repeated multiple times. Its main use is to allow network interfaces be created 2632 as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface 2633 position on the PCI bus. 2634 2635 Here is an example of use: 2636 2637 .. parsed-literal:: 2638 2639 -netdev user,id=internet \\ 2640 -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\ 2641 -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev 2642 2643 In the guest OS, the device should then appear as ``eno1``: 2644 2645 ..parsed-literal:: 2646 2647 $ ip -brief l 2648 lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP> 2649 eno1 UP 50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP> 2650 2651 Currently, the PCI device has to be attached to the root bus. 2652 2653ERST 2654 2655DEFHEADING() 2656 2657DEFHEADING(Network options:) 2658 2659DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, 2660#ifdef CONFIG_SLIRP 2661 "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n" 2662 " [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n" 2663 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n" 2664 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n" 2665 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]" 2666#ifndef _WIN32 2667 "[,smb=dir[,smbserver=addr]]\n" 2668#endif 2669 " configure a user mode network backend with ID 'str',\n" 2670 " its DHCP server and optional services\n" 2671#endif 2672#ifdef _WIN32 2673 "-netdev tap,id=str,ifname=name\n" 2674 " configure a host TAP network backend with ID 'str'\n" 2675#else 2676 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n" 2677 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" 2678 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" 2679 " [,poll-us=n]\n" 2680 " configure a host TAP network backend with ID 'str'\n" 2681 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2682 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n" 2683 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n" 2684 " to deconfigure it\n" 2685 " use '[down]script=no' to disable script execution\n" 2686 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n" 2687 " configure it\n" 2688 " use 'fd=h' to connect to an already opened TAP interface\n" 2689 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n" 2690 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n" 2691 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n" 2692 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" 2693 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" 2694 " use vhost=on to enable experimental in kernel accelerator\n" 2695 " (only has effect for virtio guests which use MSIX)\n" 2696 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" 2697 " use 'vhostfd=h' to connect to an already opened vhost net device\n" 2698 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n" 2699 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n" 2700 " use 'poll-us=n' to specify the maximum number of microseconds that could be\n" 2701 " spent on busy polling for vhost net\n" 2702 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n" 2703 " configure a host TAP network backend with ID 'str' that is\n" 2704 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2705 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n" 2706#endif 2707#ifdef __linux__ 2708 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n" 2709 " [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n" 2710 " [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n" 2711 " [,rxcookie=rxcookie][,offset=offset]\n" 2712 " configure a network backend with ID 'str' connected to\n" 2713 " an Ethernet over L2TPv3 pseudowire.\n" 2714 " Linux kernel 3.3+ as well as most routers can talk\n" 2715 " L2TPv3. This transport allows connecting a VM to a VM,\n" 2716 " VM to a router and even VM to Host. It is a nearly-universal\n" 2717 " standard (RFC3931). Note - this implementation uses static\n" 2718 " pre-configured tunnels (same as the Linux kernel).\n" 2719 " use 'src=' to specify source address\n" 2720 " use 'dst=' to specify destination address\n" 2721 " use 'udp=on' to specify udp encapsulation\n" 2722 " use 'srcport=' to specify source udp port\n" 2723 " use 'dstport=' to specify destination udp port\n" 2724 " use 'ipv6=on' to force v6\n" 2725 " L2TPv3 uses cookies to prevent misconfiguration as\n" 2726 " well as a weak security measure\n" 2727 " use 'rxcookie=0x012345678' to specify a rxcookie\n" 2728 " use 'txcookie=0x012345678' to specify a txcookie\n" 2729 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n" 2730 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n" 2731 " use 'pincounter=on' to work around broken counter handling in peer\n" 2732 " use 'offset=X' to add an extra offset between header and data\n" 2733#endif 2734 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n" 2735 " configure a network backend to connect to another network\n" 2736 " using a socket connection\n" 2737 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n" 2738 " configure a network backend to connect to a multicast maddr and port\n" 2739 " use 'localaddr=addr' to specify the host address to send packets from\n" 2740 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n" 2741 " configure a network backend to connect to another network\n" 2742 " using an UDP tunnel\n" 2743#ifdef CONFIG_VDE 2744 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n" 2745 " configure a network backend to connect to port 'n' of a vde switch\n" 2746 " running on host and listening for incoming connections on 'socketpath'.\n" 2747 " Use group 'groupname' and mode 'octalmode' to change default\n" 2748 " ownership and permissions for communication port.\n" 2749#endif 2750#ifdef CONFIG_NETMAP 2751 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n" 2752 " attach to the existing netmap-enabled network interface 'name', or to a\n" 2753 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n" 2754 " netmap device, defaults to '/dev/netmap')\n" 2755#endif 2756#ifdef CONFIG_POSIX 2757 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" 2758 " configure a vhost-user network, backed by a chardev 'dev'\n" 2759#endif 2760#ifdef __linux__ 2761 "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n" 2762 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n" 2763#endif 2764 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n" 2765 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL) 2766DEF("nic", HAS_ARG, QEMU_OPTION_nic, 2767 "-nic [tap|bridge|" 2768#ifdef CONFIG_SLIRP 2769 "user|" 2770#endif 2771#ifdef __linux__ 2772 "l2tpv3|" 2773#endif 2774#ifdef CONFIG_VDE 2775 "vde|" 2776#endif 2777#ifdef CONFIG_NETMAP 2778 "netmap|" 2779#endif 2780#ifdef CONFIG_POSIX 2781 "vhost-user|" 2782#endif 2783 "socket][,option][,...][mac=macaddr]\n" 2784 " initialize an on-board / default host NIC (using MAC address\n" 2785 " macaddr) and connect it to the given host network backend\n" 2786 "-nic none use it alone to have zero network devices (the default is to\n" 2787 " provided a 'user' network connection)\n", 2788 QEMU_ARCH_ALL) 2789DEF("net", HAS_ARG, QEMU_OPTION_net, 2790 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" 2791 " configure or create an on-board (or machine default) NIC and\n" 2792 " connect it to hub 0 (please use -nic unless you need a hub)\n" 2793 "-net [" 2794#ifdef CONFIG_SLIRP 2795 "user|" 2796#endif 2797 "tap|" 2798 "bridge|" 2799#ifdef CONFIG_VDE 2800 "vde|" 2801#endif 2802#ifdef CONFIG_NETMAP 2803 "netmap|" 2804#endif 2805 "socket][,option][,option][,...]\n" 2806 " old way to initialize a host network interface\n" 2807 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL) 2808SRST 2809``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]`` 2810 This option is a shortcut for configuring both the on-board 2811 (default) guest NIC hardware and the host network backend in one go. 2812 The host backend options are the same as with the corresponding 2813 ``-netdev`` options below. The guest NIC model can be set with 2814 ``model=modelname``. Use ``model=help`` to list the available device 2815 types. The hardware MAC address can be set with ``mac=macaddr``. 2816 2817 The following two example do exactly the same, to show how ``-nic`` 2818 can be used to shorten the command line length: 2819 2820 .. parsed-literal:: 2821 2822 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32 2823 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32 2824 2825``-nic none`` 2826 Indicate that no network devices should be configured. It is used to 2827 override the default configuration (default NIC with "user" host 2828 network backend) which is activated if no other networking options 2829 are provided. 2830 2831``-netdev user,id=id[,option][,option][,...]`` 2832 Configure user mode host network backend which requires no 2833 administrator privilege to run. Valid options are: 2834 2835 ``id=id`` 2836 Assign symbolic name for use in monitor commands. 2837 2838 ``ipv4=on|off and ipv6=on|off`` 2839 Specify that either IPv4 or IPv6 must be enabled. If neither is 2840 specified both protocols are enabled. 2841 2842 ``net=addr[/mask]`` 2843 Set IP network address the guest will see. Optionally specify 2844 the netmask, either in the form a.b.c.d or as number of valid 2845 top-most bits. Default is 10.0.2.0/24. 2846 2847 ``host=addr`` 2848 Specify the guest-visible address of the host. Default is the 2849 2nd IP in the guest network, i.e. x.x.x.2. 2850 2851 ``ipv6-net=addr[/int]`` 2852 Set IPv6 network address the guest will see (default is 2853 fec0::/64). The network prefix is given in the usual hexadecimal 2854 IPv6 address notation. The prefix size is optional, and is given 2855 as the number of valid top-most bits (default is 64). 2856 2857 ``ipv6-host=addr`` 2858 Specify the guest-visible IPv6 address of the host. Default is 2859 the 2nd IPv6 in the guest network, i.e. xxxx::2. 2860 2861 ``restrict=on|off`` 2862 If this option is enabled, the guest will be isolated, i.e. it 2863 will not be able to contact the host and no guest IP packets 2864 will be routed over the host to the outside. This option does 2865 not affect any explicitly set forwarding rules. 2866 2867 ``hostname=name`` 2868 Specifies the client hostname reported by the built-in DHCP 2869 server. 2870 2871 ``dhcpstart=addr`` 2872 Specify the first of the 16 IPs the built-in DHCP server can 2873 assign. Default is the 15th to 31st IP in the guest network, 2874 i.e. x.x.x.15 to x.x.x.31. 2875 2876 ``dns=addr`` 2877 Specify the guest-visible address of the virtual nameserver. The 2878 address must be different from the host address. Default is the 2879 3rd IP in the guest network, i.e. x.x.x.3. 2880 2881 ``ipv6-dns=addr`` 2882 Specify the guest-visible address of the IPv6 virtual 2883 nameserver. The address must be different from the host address. 2884 Default is the 3rd IP in the guest network, i.e. xxxx::3. 2885 2886 ``dnssearch=domain`` 2887 Provides an entry for the domain-search list sent by the 2888 built-in DHCP server. More than one domain suffix can be 2889 transmitted by specifying this option multiple times. If 2890 supported, this will cause the guest to automatically try to 2891 append the given domain suffix(es) in case a domain name can not 2892 be resolved. 2893 2894 Example: 2895 2896 .. parsed-literal:: 2897 2898 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org 2899 2900 ``domainname=domain`` 2901 Specifies the client domain name reported by the built-in DHCP 2902 server. 2903 2904 ``tftp=dir`` 2905 When using the user mode network stack, activate a built-in TFTP 2906 server. The files in dir will be exposed as the root of a TFTP 2907 server. The TFTP client on the guest must be configured in 2908 binary mode (use the command ``bin`` of the Unix TFTP client). 2909 2910 ``tftp-server-name=name`` 2911 In BOOTP reply, broadcast name as the "TFTP server name" 2912 (RFC2132 option 66). This can be used to advise the guest to 2913 load boot files or configurations from a different server than 2914 the host address. 2915 2916 ``bootfile=file`` 2917 When using the user mode network stack, broadcast file as the 2918 BOOTP filename. In conjunction with ``tftp``, this can be used 2919 to network boot a guest from a local directory. 2920 2921 Example (using pxelinux): 2922 2923 .. parsed-literal:: 2924 2925 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\ 2926 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0 2927 2928 ``smb=dir[,smbserver=addr]`` 2929 When using the user mode network stack, activate a built-in SMB 2930 server so that Windows OSes can access to the host files in 2931 ``dir`` transparently. The IP address of the SMB server can be 2932 set to addr. By default the 4th IP in the guest network is used, 2933 i.e. x.x.x.4. 2934 2935 In the guest Windows OS, the line: 2936 2937 :: 2938 2939 10.0.2.4 smbserver 2940 2941 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows 2942 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows 2943 NT/2000). 2944 2945 Then ``dir`` can be accessed in ``\\smbserver\qemu``. 2946 2947 Note that a SAMBA server must be installed on the host OS. 2948 2949 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport`` 2950 Redirect incoming TCP or UDP connections to the host port 2951 hostport to the guest IP address guestaddr on guest port 2952 guestport. If guestaddr is not specified, its value is x.x.x.15 2953 (default first address given by the built-in DHCP server). By 2954 specifying hostaddr, the rule can be bound to a specific host 2955 interface. If no connection type is set, TCP is used. This 2956 option can be given multiple times. 2957 2958 For example, to redirect host X11 connection from screen 1 to 2959 guest screen 0, use the following: 2960 2961 .. parsed-literal:: 2962 2963 # on the host 2964 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000 2965 # this host xterm should open in the guest X11 server 2966 xterm -display :1 2967 2968 To redirect telnet connections from host port 5555 to telnet 2969 port on the guest, use the following: 2970 2971 .. parsed-literal:: 2972 2973 # on the host 2974 |qemu_system| -nic user,hostfwd=tcp::5555-:23 2975 telnet localhost 5555 2976 2977 Then when you use on the host ``telnet localhost 5555``, you 2978 connect to the guest telnet server. 2979 2980 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command`` 2981 Forward guest TCP connections to the IP address server on port 2982 port to the character device dev or to a program executed by 2983 cmd:command which gets spawned for each connection. This option 2984 can be given multiple times. 2985 2986 You can either use a chardev directly and have that one used 2987 throughout QEMU's lifetime, like in the following example: 2988 2989 .. parsed-literal:: 2990 2991 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever 2992 # the guest accesses it 2993 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 2994 2995 Or you can execute a command on every TCP connection established 2996 by the guest, so that QEMU behaves similar to an inetd process 2997 for that virtual server: 2998 2999 .. parsed-literal:: 3000 3001 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234 3002 # and connect the TCP stream to its stdin/stdout 3003 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321' 3004 3005``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]`` 3006 Configure a host TAP network backend with ID id. 3007 3008 Use the network script file to configure it and the network script 3009 dfile to deconfigure it. If name is not provided, the OS 3010 automatically provides one. The default network configure script is 3011 ``/etc/qemu-ifup`` and the default network deconfigure script is 3012 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to 3013 disable script execution. 3014 3015 If running QEMU as an unprivileged user, use the network helper 3016 to configure the TAP interface and attach it to the bridge. 3017 The default network helper executable is 3018 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3019 ``br0``. 3020 3021 ``fd``\ =h can be used to specify the handle of an already opened 3022 host TAP interface. 3023 3024 Examples: 3025 3026 .. parsed-literal:: 3027 3028 #launch a QEMU instance with the default network script 3029 |qemu_system| linux.img -nic tap 3030 3031 .. parsed-literal:: 3032 3033 #launch a QEMU instance with two NICs, each one connected 3034 #to a TAP device 3035 |qemu_system| linux.img \\ 3036 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\ 3037 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1 3038 3039 .. parsed-literal:: 3040 3041 #launch a QEMU instance with the default network helper to 3042 #connect a TAP device to bridge br0 3043 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\ 3044 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper" 3045 3046``-netdev bridge,id=id[,br=bridge][,helper=helper]`` 3047 Connect a host TAP network interface to a host bridge device. 3048 3049 Use the network helper helper to configure the TAP interface and 3050 attach it to the bridge. The default network helper executable is 3051 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3052 ``br0``. 3053 3054 Examples: 3055 3056 .. parsed-literal:: 3057 3058 #launch a QEMU instance with the default network helper to 3059 #connect a TAP device to bridge br0 3060 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1 3061 3062 .. parsed-literal:: 3063 3064 #launch a QEMU instance with the default network helper to 3065 #connect a TAP device to bridge qemubr0 3066 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1 3067 3068``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]`` 3069 This host network backend can be used to connect the guest's network 3070 to another QEMU virtual machine using a TCP socket connection. If 3071 ``listen`` is specified, QEMU waits for incoming connections on port 3072 (host is optional). ``connect`` is used to connect to another QEMU 3073 instance using the ``listen`` option. ``fd``\ =h specifies an 3074 already opened TCP socket. 3075 3076 Example: 3077 3078 .. parsed-literal:: 3079 3080 # launch a first QEMU instance 3081 |qemu_system| linux.img \\ 3082 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3083 -netdev socket,id=n1,listen=:1234 3084 # connect the network of this instance to the network of the first instance 3085 |qemu_system| linux.img \\ 3086 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3087 -netdev socket,id=n2,connect=127.0.0.1:1234 3088 3089``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]`` 3090 Configure a socket host network backend to share the guest's network 3091 traffic with another QEMU virtual machines using a UDP multicast 3092 socket, effectively making a bus for every QEMU with same multicast 3093 address maddr and port. NOTES: 3094 3095 1. Several QEMU can be running on different hosts and share same bus 3096 (assuming correct multicast setup for these hosts). 3097 3098 2. mcast support is compatible with User Mode Linux (argument 3099 ``ethN=mcast``), see http://user-mode-linux.sf.net. 3100 3101 3. Use ``fd=h`` to specify an already opened UDP multicast socket. 3102 3103 Example: 3104 3105 .. parsed-literal:: 3106 3107 # launch one QEMU instance 3108 |qemu_system| linux.img \\ 3109 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3110 -netdev socket,id=n1,mcast=230.0.0.1:1234 3111 # launch another QEMU instance on same "bus" 3112 |qemu_system| linux.img \\ 3113 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3114 -netdev socket,id=n2,mcast=230.0.0.1:1234 3115 # launch yet another QEMU instance on same "bus" 3116 |qemu_system| linux.img \\ 3117 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\ 3118 -netdev socket,id=n3,mcast=230.0.0.1:1234 3119 3120 Example (User Mode Linux compat.): 3121 3122 .. parsed-literal:: 3123 3124 # launch QEMU instance (note mcast address selected is UML's default) 3125 |qemu_system| linux.img \\ 3126 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3127 -netdev socket,id=n1,mcast=239.192.168.1:1102 3128 # launch UML 3129 /path/to/linux ubd0=/path/to/root_fs eth0=mcast 3130 3131 Example (send packets from host's 1.2.3.4): 3132 3133 .. parsed-literal:: 3134 3135 |qemu_system| linux.img \\ 3136 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3137 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4 3138 3139``-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]`` 3140 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931) 3141 is a popular protocol to transport Ethernet (and other Layer 2) data 3142 frames between two systems. It is present in routers, firewalls and 3143 the Linux kernel (from version 3.3 onwards). 3144 3145 This transport allows a VM to communicate to another VM, router or 3146 firewall directly. 3147 3148 ``src=srcaddr`` 3149 source address (mandatory) 3150 3151 ``dst=dstaddr`` 3152 destination address (mandatory) 3153 3154 ``udp`` 3155 select udp encapsulation (default is ip). 3156 3157 ``srcport=srcport`` 3158 source udp port. 3159 3160 ``dstport=dstport`` 3161 destination udp port. 3162 3163 ``ipv6`` 3164 force v6, otherwise defaults to v4. 3165 3166 ``rxcookie=rxcookie``; \ ``txcookie=txcookie`` 3167 Cookies are a weak form of security in the l2tpv3 specification. 3168 Their function is mostly to prevent misconfiguration. By default 3169 they are 32 bit. 3170 3171 ``cookie64`` 3172 Set cookie size to 64 bit instead of the default 32 3173 3174 ``counter=off`` 3175 Force a 'cut-down' L2TPv3 with no counter as in 3176 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00 3177 3178 ``pincounter=on`` 3179 Work around broken counter handling in peer. This may also help 3180 on networks which have packet reorder. 3181 3182 ``offset=offset`` 3183 Add an extra offset between header and data 3184 3185 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to 3186 the bridge br-lan on the remote Linux host 1.2.3.4: 3187 3188 .. parsed-literal:: 3189 3190 # Setup tunnel on linux host using raw ip as encapsulation 3191 # on 1.2.3.4 3192 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\ 3193 encap udp udp_sport 16384 udp_dport 16384 3194 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\ 3195 0xFFFFFFFF peer_session_id 0xFFFFFFFF 3196 ifconfig vmtunnel0 mtu 1500 3197 ifconfig vmtunnel0 up 3198 brctl addif br-lan vmtunnel0 3199 3200 3201 # on 4.3.2.1 3202 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter 3203 3204 |qemu_system| linux.img -device e1000,netdev=n1 \\ 3205 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter 3206 3207``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]`` 3208 Configure VDE backend to connect to PORT n of a vde switch running 3209 on host and listening for incoming connections on socketpath. Use 3210 GROUP groupname and MODE octalmode to change default ownership and 3211 permissions for communication port. This option is only available if 3212 QEMU has been compiled with vde support enabled. 3213 3214 Example: 3215 3216 .. parsed-literal:: 3217 3218 # launch vde switch 3219 vde_switch -F -sock /tmp/myswitch 3220 # launch QEMU instance 3221 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch 3222 3223``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]`` 3224 Establish a vhost-user netdev, backed by a chardev id. The chardev 3225 should be a unix domain socket backed one. The vhost-user uses a 3226 specifically defined protocol to pass vhost ioctl replacement 3227 messages to an application on the other end of the socket. On 3228 non-MSIX guests, the feature can be forced with vhostforce. Use 3229 'queues=n' to specify the number of queues to be created for 3230 multiqueue vhost-user. 3231 3232 Example: 3233 3234 :: 3235 3236 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \ 3237 -numa node,memdev=mem \ 3238 -chardev socket,id=chr0,path=/path/to/socket \ 3239 -netdev type=vhost-user,id=net0,chardev=chr0 \ 3240 -device virtio-net-pci,netdev=net0 3241 3242``-netdev vhost-vdpa,vhostdev=/path/to/dev`` 3243 Establish a vhost-vdpa netdev. 3244 3245 vDPA device is a device that uses a datapath which complies with 3246 the virtio specifications with a vendor specific control path. 3247 vDPA devices can be both physically located on the hardware or 3248 emulated by software. 3249 3250``-netdev hubport,id=id,hubid=hubid[,netdev=nd]`` 3251 Create a hub port on the emulated hub with ID hubid. 3252 3253 The hubport netdev lets you connect a NIC to a QEMU emulated hub 3254 instead of a single netdev. Alternatively, you can also connect the 3255 hubport to another netdev with ID nd by using the ``netdev=nd`` 3256 option. 3257 3258``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]`` 3259 Legacy option to configure or create an on-board (or machine 3260 default) Network Interface Card(NIC) and connect it either to the 3261 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd. 3262 If model is omitted, then the default NIC model associated with the 3263 machine type is used. Note that the default NIC model may change in 3264 future QEMU releases, so it is highly recommended to always specify 3265 a model. Optionally, the MAC address can be changed to mac, the 3266 device address set to addr (PCI cards only), and a name can be 3267 assigned for use in monitor commands. Optionally, for PCI cards, you 3268 can specify the number v of MSI-X vectors that the card should have; 3269 this option currently only affects virtio cards; set v = 0 to 3270 disable MSI-X. If no ``-net`` option is specified, a single NIC is 3271 created. QEMU can emulate several different models of network card. 3272 Use ``-net nic,model=help`` for a list of available devices for your 3273 target. 3274 3275``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]`` 3276 Configure a host network backend (with the options corresponding to 3277 the same ``-netdev`` option) and connect it to the emulated hub 0 3278 (the default hub). Use name to specify the name of the hub port. 3279ERST 3280 3281DEFHEADING() 3282 3283DEFHEADING(Character device options:) 3284 3285DEF("chardev", HAS_ARG, QEMU_OPTION_chardev, 3286 "-chardev help\n" 3287 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3288 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n" 3289 " [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n" 3290 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n" 3291 "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n" 3292 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n" 3293 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n" 3294 " [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n" 3295 " [,logfile=PATH][,logappend=on|off]\n" 3296 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3297 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n" 3298 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3299 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n" 3300 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3301 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3302#ifdef _WIN32 3303 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3304 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3305#else 3306 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3307 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n" 3308#endif 3309#ifdef CONFIG_BRLAPI 3310 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3311#endif 3312#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ 3313 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) 3314 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3315 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3316#endif 3317#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__) 3318 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3319 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3320#endif 3321#if defined(CONFIG_SPICE) 3322 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3323 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3324#endif 3325 , QEMU_ARCH_ALL 3326) 3327 3328SRST 3329The general form of a character device option is: 3330 3331``-chardev backend,id=id[,mux=on|off][,options]`` 3332 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, 3333 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``, 3334 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``, 3335 ``spicevmc``, ``spiceport``. The specific backend will determine the 3336 applicable options. 3337 3338 Use ``-chardev help`` to print all available chardev backend types. 3339 3340 All devices must have an id, which can be any string up to 127 3341 characters long. It is used to uniquely identify this device in 3342 other command line directives. 3343 3344 A character device may be used in multiplexing mode by multiple 3345 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is 3346 a "1:N" device, and here the "1" end is your specified chardev 3347 backend, and the "N" end is the various parts of QEMU that can talk 3348 to a chardev. If you create a chardev with ``id=myid`` and 3349 ``mux=on``, QEMU will create a multiplexer with your specified ID, 3350 and you can then configure multiple front ends to use that chardev 3351 ID for their input/output. Up to four different front ends can be 3352 connected to a single multiplexed chardev. (Without multiplexing 3353 enabled, a chardev can only be used by a single front end.) For 3354 instance you could use this to allow a single stdio chardev to be 3355 used by two serial ports and the QEMU monitor: 3356 3357 :: 3358 3359 -chardev stdio,mux=on,id=char0 \ 3360 -mon chardev=char0,mode=readline \ 3361 -serial chardev:char0 \ 3362 -serial chardev:char0 3363 3364 You can have more than one multiplexer in a system configuration; 3365 for instance you could have a TCP port multiplexed between UART 0 3366 and UART 1, and stdio multiplexed between the QEMU monitor and a 3367 parallel port: 3368 3369 :: 3370 3371 -chardev stdio,mux=on,id=char0 \ 3372 -mon chardev=char0,mode=readline \ 3373 -parallel chardev:char0 \ 3374 -chardev tcp,...,mux=on,id=char1 \ 3375 -serial chardev:char1 \ 3376 -serial chardev:char1 3377 3378 When you're using a multiplexed character device, some escape 3379 sequences are interpreted in the input. See the chapter about 3380 :ref:`keys in the character backend multiplexer` in the 3381 System Emulation Users Guide for more details. 3382 3383 Note that some other command line options may implicitly create 3384 multiplexed character backends; for instance ``-serial mon:stdio`` 3385 creates a multiplexed stdio backend connected to the serial port and 3386 the QEMU monitor, and ``-nographic`` also multiplexes the console 3387 and the monitor to stdio. 3388 3389 There is currently no support for multiplexing in the other 3390 direction (where a single QEMU front end takes input and output from 3391 multiple chardevs). 3392 3393 Every backend supports the ``logfile`` option, which supplies the 3394 path to a file to record all data transmitted via the backend. The 3395 ``logappend`` option controls whether the log file will be truncated 3396 or appended to when opened. 3397 3398The available backends are: 3399 3400``-chardev null,id=id`` 3401 A void device. This device will not emit any data, and will drop any 3402 data it receives. The null backend does not take any options. 3403 3404``-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]`` 3405 Create a two-way stream socket, which can be either a TCP or a unix 3406 socket. A unix socket will be created if ``path`` is specified. 3407 Behaviour is undefined if TCP options are specified for a unix 3408 socket. 3409 3410 ``server=on|off`` specifies that the socket shall be a listening socket. 3411 3412 ``wait=on|off`` specifies that QEMU should not block waiting for a client 3413 to connect to a listening socket. 3414 3415 ``telnet=on|off`` specifies that traffic on the socket should interpret 3416 telnet escape sequences. 3417 3418 ``websocket=on|off`` specifies that the socket uses WebSocket protocol for 3419 communication. 3420 3421 ``reconnect`` sets the timeout for reconnecting on non-server 3422 sockets when the remote end goes away. qemu will delay this many 3423 seconds and then attempt to reconnect. Zero disables reconnecting, 3424 and is the default. 3425 3426 ``tls-creds`` requests enablement of the TLS protocol for 3427 encryption, and specifies the id of the TLS credentials to use for 3428 the handshake. The credentials must be previously created with the 3429 ``-object tls-creds`` argument. 3430 3431 ``tls-auth`` provides the ID of the QAuthZ authorization object 3432 against which the client's x509 distinguished name will be 3433 validated. This object is only resolved at time of use, so can be 3434 deleted and recreated on the fly while the chardev server is active. 3435 If missing, it will default to denying access. 3436 3437 TCP and unix socket options are given below: 3438 3439 ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]`` 3440 ``host`` for a listening socket specifies the local address to 3441 be bound. For a connecting socket species the remote host to 3442 connect to. ``host`` is optional for listening sockets. If not 3443 specified it defaults to ``0.0.0.0``. 3444 3445 ``port`` for a listening socket specifies the local port to be 3446 bound. For a connecting socket specifies the port on the remote 3447 host to connect to. ``port`` can be given as either a port 3448 number or a service name. ``port`` is required. 3449 3450 ``to`` is only relevant to listening sockets. If it is 3451 specified, and ``port`` cannot be bound, QEMU will attempt to 3452 bind to subsequent ports up to and including ``to`` until it 3453 succeeds. ``to`` must be specified as a port number. 3454 3455 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 3456 or IPv6 must be used. If neither is specified the socket may 3457 use either protocol. 3458 3459 ``nodelay=on|off`` disables the Nagle algorithm. 3460 3461 ``unix options: path=path[,abstract=on|off][,tight=on|off]`` 3462 ``path`` specifies the local path of the unix socket. ``path`` 3463 is required. 3464 ``abstract=on|off`` specifies the use of the abstract socket namespace, 3465 rather than the filesystem. Optional, defaults to false. 3466 ``tight=on|off`` sets the socket length of abstract sockets to their minimum, 3467 rather than the full sun_path length. Optional, defaults to true. 3468 3469``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]`` 3470 Sends all traffic from the guest to a remote host over UDP. 3471 3472 ``host`` specifies the remote host to connect to. If not specified 3473 it defaults to ``localhost``. 3474 3475 ``port`` specifies the port on the remote host to connect to. 3476 ``port`` is required. 3477 3478 ``localaddr`` specifies the local address to bind to. If not 3479 specified it defaults to ``0.0.0.0``. 3480 3481 ``localport`` specifies the local port to bind to. If not specified 3482 any available local port will be used. 3483 3484 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used. 3485 If neither is specified the device may use either protocol. 3486 3487``-chardev msmouse,id=id`` 3488 Forward QEMU's emulated msmouse events to the guest. ``msmouse`` 3489 does not take any options. 3490 3491``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]`` 3492 Connect to a QEMU text console. ``vc`` may optionally be given a 3493 specific size. 3494 3495 ``width`` and ``height`` specify the width and height respectively 3496 of the console, in pixels. 3497 3498 ``cols`` and ``rows`` specify that the console be sized to fit a 3499 text console with the given dimensions. 3500 3501``-chardev ringbuf,id=id[,size=size]`` 3502 Create a ring buffer with fixed size ``size``. size must be a power 3503 of two and defaults to ``64K``. 3504 3505``-chardev file,id=id,path=path`` 3506 Log all traffic received from the guest to a file. 3507 3508 ``path`` specifies the path of the file to be opened. This file will 3509 be created if it does not already exist, and overwritten if it does. 3510 ``path`` is required. 3511 3512``-chardev pipe,id=id,path=path`` 3513 Create a two-way connection to the guest. The behaviour differs 3514 slightly between Windows hosts and other hosts: 3515 3516 On Windows, a single duplex pipe will be created at 3517 ``\\.pipe\path``. 3518 3519 On other hosts, 2 pipes will be created called ``path.in`` and 3520 ``path.out``. Data written to ``path.in`` will be received by the 3521 guest. Data written by the guest can be read from ``path.out``. QEMU 3522 will not create these fifos, and requires them to be present. 3523 3524 ``path`` forms part of the pipe path as described above. ``path`` is 3525 required. 3526 3527``-chardev console,id=id`` 3528 Send traffic from the guest to QEMU's standard output. ``console`` 3529 does not take any options. 3530 3531 ``console`` is only available on Windows hosts. 3532 3533``-chardev serial,id=id,path=path`` 3534 Send traffic from the guest to a serial device on the host. 3535 3536 On Unix hosts serial will actually accept any tty device, not only 3537 serial lines. 3538 3539 ``path`` specifies the name of the serial device to open. 3540 3541``-chardev pty,id=id`` 3542 Create a new pseudo-terminal on the host and connect to it. ``pty`` 3543 does not take any options. 3544 3545 ``pty`` is not available on Windows hosts. 3546 3547``-chardev stdio,id=id[,signal=on|off]`` 3548 Connect to standard input and standard output of the QEMU process. 3549 3550 ``signal`` controls if signals are enabled on the terminal, that 3551 includes exiting QEMU with the key sequence Control-c. This option 3552 is enabled by default, use ``signal=off`` to disable it. 3553 3554``-chardev braille,id=id`` 3555 Connect to a local BrlAPI server. ``braille`` does not take any 3556 options. 3557 3558``-chardev tty,id=id,path=path`` 3559 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD 3560 and DragonFlyBSD hosts. It is an alias for ``serial``. 3561 3562 ``path`` specifies the path to the tty. ``path`` is required. 3563 3564``-chardev parallel,id=id,path=path`` 3565 \ 3566``-chardev parport,id=id,path=path`` 3567 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD 3568 hosts. 3569 3570 Connect to a local parallel port. 3571 3572 ``path`` specifies the path to the parallel port device. ``path`` is 3573 required. 3574 3575``-chardev spicevmc,id=id,debug=debug,name=name`` 3576 ``spicevmc`` is only available when spice support is built in. 3577 3578 ``debug`` debug level for spicevmc 3579 3580 ``name`` name of spice channel to connect to 3581 3582 Connect to a spice virtual machine channel, such as vdiport. 3583 3584``-chardev spiceport,id=id,debug=debug,name=name`` 3585 ``spiceport`` is only available when spice support is built in. 3586 3587 ``debug`` debug level for spicevmc 3588 3589 ``name`` name of spice port to connect to 3590 3591 Connect to a spice port, allowing a Spice client to handle the 3592 traffic identified by a name (preferably a fqdn). 3593ERST 3594 3595DEFHEADING() 3596 3597#ifdef CONFIG_TPM 3598DEFHEADING(TPM device options:) 3599 3600DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \ 3601 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n" 3602 " use path to provide path to a character device; default is /dev/tpm0\n" 3603 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n" 3604 " not provided it will be searched for in /sys/class/misc/tpm?/device\n" 3605 "-tpmdev emulator,id=id,chardev=dev\n" 3606 " configure the TPM device using chardev backend\n", 3607 QEMU_ARCH_ALL) 3608SRST 3609The general form of a TPM device option is: 3610 3611``-tpmdev backend,id=id[,options]`` 3612 The specific backend type will determine the applicable options. The 3613 ``-tpmdev`` option creates the TPM backend and requires a 3614 ``-device`` option that specifies the TPM frontend interface model. 3615 3616 Use ``-tpmdev help`` to print all available TPM backend types. 3617 3618The available backends are: 3619 3620``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path`` 3621 (Linux-host only) Enable access to the host's TPM using the 3622 passthrough driver. 3623 3624 ``path`` specifies the path to the host's TPM device, i.e., on a 3625 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by 3626 default ``/dev/tpm0`` is used. 3627 3628 ``cancel-path`` specifies the path to the host TPM device's sysfs 3629 entry allowing for cancellation of an ongoing TPM command. 3630 ``cancel-path`` is optional and by default QEMU will search for the 3631 sysfs entry to use. 3632 3633 Some notes about using the host's TPM with the passthrough driver: 3634 3635 The TPM device accessed by the passthrough driver must not be used 3636 by any other application on the host. 3637 3638 Since the host's firmware (BIOS/UEFI) has already initialized the 3639 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize 3640 the TPM again and may therefore not show a TPM-specific menu that 3641 would otherwise allow the user to configure the TPM, e.g., allow the 3642 user to enable/disable or activate/deactivate the TPM. Further, if 3643 TPM ownership is released from within a VM then the host's TPM will 3644 get disabled and deactivated. To enable and activate the TPM again 3645 afterwards, the host has to be rebooted and the user is required to 3646 enter the firmware's menu to enable and activate the TPM. If the TPM 3647 is left disabled and/or deactivated most TPM commands will fail. 3648 3649 To create a passthrough TPM use the following two options: 3650 3651 :: 3652 3653 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0 3654 3655 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by 3656 ``tpmdev=tpm0`` in the device option. 3657 3658``-tpmdev emulator,id=id,chardev=dev`` 3659 (Linux-host only) Enable access to a TPM emulator using Unix domain 3660 socket based chardev backend. 3661 3662 ``chardev`` specifies the unique ID of a character device backend 3663 that provides connection to the software TPM server. 3664 3665 To create a TPM emulator backend device with chardev socket backend: 3666 3667 :: 3668 3669 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0 3670ERST 3671 3672DEFHEADING() 3673 3674#endif 3675 3676DEFHEADING(Linux/Multiboot boot specific:) 3677SRST 3678When using these options, you can use a given Linux or Multiboot kernel 3679without installing it in the disk image. It can be useful for easier 3680testing of various kernels. 3681 3682 3683ERST 3684 3685DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \ 3686 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL) 3687SRST 3688``-kernel bzImage`` 3689 Use bzImage as kernel image. The kernel can be either a Linux kernel 3690 or in multiboot format. 3691ERST 3692 3693DEF("append", HAS_ARG, QEMU_OPTION_append, \ 3694 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL) 3695SRST 3696``-append cmdline`` 3697 Use cmdline as kernel command line 3698ERST 3699 3700DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \ 3701 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL) 3702SRST 3703``-initrd file`` 3704 Use file as initial ram disk. 3705 3706``-initrd "file1 arg=foo,file2"`` 3707 This syntax is only available with multiboot. 3708 3709 Use file1 and file2 as modules and pass arg=foo as parameter to the 3710 first module. 3711ERST 3712 3713DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \ 3714 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL) 3715SRST 3716``-dtb file`` 3717 Use file as a device tree binary (dtb) image and pass it to the 3718 kernel on boot. 3719ERST 3720 3721DEFHEADING() 3722 3723DEFHEADING(Debug/Expert options:) 3724 3725DEF("compat", HAS_ARG, QEMU_OPTION_compat, 3726 "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n" 3727 " Policy for handling deprecated management interfaces\n" 3728 "-compat [unstable-input=accept|reject|crash][,unstable-output=accept|hide]\n" 3729 " Policy for handling unstable management interfaces\n", 3730 QEMU_ARCH_ALL) 3731SRST 3732``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]`` 3733 Set policy for handling deprecated management interfaces (experimental): 3734 3735 ``deprecated-input=accept`` (default) 3736 Accept deprecated commands and arguments 3737 ``deprecated-input=reject`` 3738 Reject deprecated commands and arguments 3739 ``deprecated-input=crash`` 3740 Crash on deprecated commands and arguments 3741 ``deprecated-output=accept`` (default) 3742 Emit deprecated command results and events 3743 ``deprecated-output=hide`` 3744 Suppress deprecated command results and events 3745 3746 Limitation: covers only syntactic aspects of QMP. 3747 3748``-compat [unstable-input=@var{input-policy}][,unstable-output=@var{output-policy}]`` 3749 Set policy for handling unstable management interfaces (experimental): 3750 3751 ``unstable-input=accept`` (default) 3752 Accept unstable commands and arguments 3753 ``unstable-input=reject`` 3754 Reject unstable commands and arguments 3755 ``unstable-input=crash`` 3756 Crash on unstable commands and arguments 3757 ``unstable-output=accept`` (default) 3758 Emit unstable command results and events 3759 ``unstable-output=hide`` 3760 Suppress unstable command results and events 3761 3762 Limitation: covers only syntactic aspects of QMP. 3763ERST 3764 3765DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg, 3766 "-fw_cfg [name=]<name>,file=<file>\n" 3767 " add named fw_cfg entry with contents from file\n" 3768 "-fw_cfg [name=]<name>,string=<str>\n" 3769 " add named fw_cfg entry with contents from string\n", 3770 QEMU_ARCH_ALL) 3771SRST 3772``-fw_cfg [name=]name,file=file`` 3773 Add named fw\_cfg entry with contents from file file. 3774 3775``-fw_cfg [name=]name,string=str`` 3776 Add named fw\_cfg entry with contents from string str. 3777 3778 The terminating NUL character of the contents of str will not be 3779 included as part of the fw\_cfg item data. To insert contents with 3780 embedded NUL characters, you have to use the file parameter. 3781 3782 The fw\_cfg entries are passed by QEMU through to the guest. 3783 3784 Example: 3785 3786 :: 3787 3788 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin 3789 3790 creates an fw\_cfg entry named opt/com.mycompany/blob with contents 3791 from ./my\_blob.bin. 3792ERST 3793 3794DEF("serial", HAS_ARG, QEMU_OPTION_serial, \ 3795 "-serial dev redirect the serial port to char device 'dev'\n", 3796 QEMU_ARCH_ALL) 3797SRST 3798``-serial dev`` 3799 Redirect the virtual serial port to host character device dev. The 3800 default device is ``vc`` in graphical mode and ``stdio`` in non 3801 graphical mode. 3802 3803 This option can be used several times to simulate up to 4 serial 3804 ports. 3805 3806 Use ``-serial none`` to disable all serial ports. 3807 3808 Available character devices are: 3809 3810 ``vc[:WxH]`` 3811 Virtual console. Optionally, a width and height can be given in 3812 pixel with 3813 3814 :: 3815 3816 vc:800x600 3817 3818 It is also possible to specify width or height in characters: 3819 3820 :: 3821 3822 vc:80Cx24C 3823 3824 ``pty`` 3825 [Linux only] Pseudo TTY (a new PTY is automatically allocated) 3826 3827 ``none`` 3828 No device is allocated. 3829 3830 ``null`` 3831 void device 3832 3833 ``chardev:id`` 3834 Use a named character device defined with the ``-chardev`` 3835 option. 3836 3837 ``/dev/XXX`` 3838 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial 3839 port parameters are set according to the emulated ones. 3840 3841 ``/dev/parportN`` 3842 [Linux only, parallel port only] Use host parallel port N. 3843 Currently SPP and EPP parallel port features can be used. 3844 3845 ``file:filename`` 3846 Write output to filename. No character can be read. 3847 3848 ``stdio`` 3849 [Unix only] standard input/output 3850 3851 ``pipe:filename`` 3852 name pipe filename 3853 3854 ``COMn`` 3855 [Windows only] Use host serial port n 3856 3857 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]`` 3858 This implements UDP Net Console. When remote\_host or src\_ip 3859 are not specified they default to ``0.0.0.0``. When not using a 3860 specified src\_port a random port is automatically chosen. 3861 3862 If you just want a simple readonly console you can use 3863 ``netcat`` or ``nc``, by starting QEMU with: 3864 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time 3865 QEMU writes something to that port it will appear in the 3866 netconsole session. 3867 3868 If you plan to send characters back via netconsole or you want 3869 to stop and start QEMU a lot of times, you should have QEMU use 3870 the same source port each time by using something like ``-serial 3871 udp::4555@:4556`` to QEMU. Another approach is to use a patched 3872 version of netcat which can listen to a TCP port and send and 3873 receive characters via udp. If you have a patched version of 3874 netcat which activates telnet remote echo and single char 3875 transfer, then you can use the following options to set up a 3876 netcat redirector to allow telnet on port 5555 to access the 3877 QEMU port. 3878 3879 ``QEMU Options:`` 3880 -serial udp::4555@:4556 3881 3882 ``netcat options:`` 3883 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T 3884 3885 ``telnet options:`` 3886 localhost 5555 3887 3888 ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]`` 3889 The TCP Net Console has two modes of operation. It can send the 3890 serial I/O to a location or wait for a connection from a 3891 location. By default the TCP Net Console is sent to host at the 3892 port. If you use the ``server=on`` option QEMU will wait for a client 3893 socket application to connect to the port before continuing, 3894 unless the ``wait=on|off`` option was specified. The ``nodelay=on|off`` 3895 option disables the Nagle buffering algorithm. The ``reconnect=on`` 3896 option only applies if ``server=no`` is set, if the connection goes 3897 down it will attempt to reconnect at the given interval. If host 3898 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a 3899 time is accepted. You can use ``telnet=on`` to connect to the 3900 corresponding character device. 3901 3902 ``Example to send tcp console to 192.168.0.2 port 4444`` 3903 -serial tcp:192.168.0.2:4444 3904 3905 ``Example to listen and wait on port 4444 for connection`` 3906 -serial tcp::4444,server=on 3907 3908 ``Example to not wait and listen on ip 192.168.0.100 port 4444`` 3909 -serial tcp:192.168.0.100:4444,server=on,wait=off 3910 3911 ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]`` 3912 The telnet protocol is used instead of raw tcp sockets. The 3913 options work the same as if you had specified ``-serial tcp``. 3914 The difference is that the port acts like a telnet server or 3915 client using telnet option negotiation. This will also allow you 3916 to send the MAGIC\_SYSRQ sequence if you use a telnet that 3917 supports sending the break sequence. Typically in unix telnet 3918 you do it with Control-] and then type "send break" followed by 3919 pressing the enter key. 3920 3921 ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]`` 3922 The WebSocket protocol is used instead of raw tcp socket. The 3923 port acts as a WebSocket server. Client mode is not supported. 3924 3925 ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]`` 3926 A unix domain socket is used instead of a tcp socket. The option 3927 works the same as if you had specified ``-serial tcp`` except 3928 the unix domain socket path is used for connections. 3929 3930 ``mon:dev_string`` 3931 This is a special option to allow the monitor to be multiplexed 3932 onto another serial port. The monitor is accessed with key 3933 sequence of Control-a and then pressing c. dev\_string should be 3934 any one of the serial devices specified above. An example to 3935 multiplex the monitor onto a telnet server listening on port 3936 4444 would be: 3937 3938 ``-serial mon:telnet::4444,server=on,wait=off`` 3939 3940 When the monitor is multiplexed to stdio in this way, Ctrl+C 3941 will not terminate QEMU any more but will be passed to the guest 3942 instead. 3943 3944 ``braille`` 3945 Braille device. This will use BrlAPI to display the braille 3946 output on a real or fake device. 3947 3948 ``msmouse`` 3949 Three button serial mouse. Configure the guest to use Microsoft 3950 protocol. 3951ERST 3952 3953DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \ 3954 "-parallel dev redirect the parallel port to char device 'dev'\n", 3955 QEMU_ARCH_ALL) 3956SRST 3957``-parallel dev`` 3958 Redirect the virtual parallel port to host device dev (same devices 3959 as the serial port). On Linux hosts, ``/dev/parportN`` can be used 3960 to use hardware devices connected on the corresponding host parallel 3961 port. 3962 3963 This option can be used several times to simulate up to 3 parallel 3964 ports. 3965 3966 Use ``-parallel none`` to disable all parallel ports. 3967ERST 3968 3969DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \ 3970 "-monitor dev redirect the monitor to char device 'dev'\n", 3971 QEMU_ARCH_ALL) 3972SRST 3973``-monitor dev`` 3974 Redirect the monitor to host device dev (same devices as the serial 3975 port). The default device is ``vc`` in graphical mode and ``stdio`` 3976 in non graphical mode. Use ``-monitor none`` to disable the default 3977 monitor. 3978ERST 3979DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \ 3980 "-qmp dev like -monitor but opens in 'control' mode\n", 3981 QEMU_ARCH_ALL) 3982SRST 3983``-qmp dev`` 3984 Like -monitor but opens in 'control' mode. 3985ERST 3986DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \ 3987 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n", 3988 QEMU_ARCH_ALL) 3989SRST 3990``-qmp-pretty dev`` 3991 Like -qmp but uses pretty JSON formatting. 3992ERST 3993 3994DEF("mon", HAS_ARG, QEMU_OPTION_mon, \ 3995 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL) 3996SRST 3997``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]`` 3998 Setup monitor on chardev name. ``mode=control`` configures 3999 a QMP monitor (a JSON RPC-style protocol) and it is not the 4000 same as HMP, the human monitor that has a "(qemu)" prompt. 4001 ``pretty`` is only valid when ``mode=control``, 4002 turning on JSON pretty printing to ease 4003 human reading and debugging. 4004ERST 4005 4006DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \ 4007 "-debugcon dev redirect the debug console to char device 'dev'\n", 4008 QEMU_ARCH_ALL) 4009SRST 4010``-debugcon dev`` 4011 Redirect the debug console to host device dev (same devices as the 4012 serial port). The debug console is an I/O port which is typically 4013 port 0xe9; writing to that I/O port sends output to this device. The 4014 default device is ``vc`` in graphical mode and ``stdio`` in non 4015 graphical mode. 4016ERST 4017 4018DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \ 4019 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL) 4020SRST 4021``-pidfile file`` 4022 Store the QEMU process PID in file. It is useful if you launch QEMU 4023 from a script. 4024ERST 4025 4026DEF("singlestep", 0, QEMU_OPTION_singlestep, \ 4027 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL) 4028SRST 4029``-singlestep`` 4030 Run the emulation in single step mode. 4031ERST 4032 4033DEF("preconfig", 0, QEMU_OPTION_preconfig, \ 4034 "--preconfig pause QEMU before machine is initialized (experimental)\n", 4035 QEMU_ARCH_ALL) 4036SRST 4037``--preconfig`` 4038 Pause QEMU for interactive configuration before the machine is 4039 created, which allows querying and configuring properties that will 4040 affect machine initialization. Use QMP command 'x-exit-preconfig' to 4041 exit the preconfig state and move to the next state (i.e. run guest 4042 if -S isn't used or pause the second time if -S is used). This 4043 option is experimental. 4044ERST 4045 4046DEF("S", 0, QEMU_OPTION_S, \ 4047 "-S freeze CPU at startup (use 'c' to start execution)\n", 4048 QEMU_ARCH_ALL) 4049SRST 4050``-S`` 4051 Do not start CPU at startup (you must type 'c' in the monitor). 4052ERST 4053 4054DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit, 4055 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n" 4056 " run qemu with overcommit hints\n" 4057 " mem-lock=on|off controls memory lock support (default: off)\n" 4058 " cpu-pm=on|off controls cpu power management (default: off)\n", 4059 QEMU_ARCH_ALL) 4060SRST 4061``-overcommit mem-lock=on|off`` 4062 \ 4063``-overcommit cpu-pm=on|off`` 4064 Run qemu with hints about host resource overcommit. The default is 4065 to assume that host overcommits all resources. 4066 4067 Locking qemu and guest memory can be enabled via ``mem-lock=on`` 4068 (disabled by default). This works when host memory is not 4069 overcommitted and reduces the worst-case latency for guest. 4070 4071 Guest ability to manage power state of host cpus (increasing latency 4072 for other processes on the same host cpu, but decreasing latency for 4073 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This 4074 works best when host CPU is not overcommitted. When used, host 4075 estimates of CPU cycle and power utilization will be incorrect, not 4076 taking into account guest idle time. 4077ERST 4078 4079DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \ 4080 "-gdb dev accept gdb connection on 'dev'. (QEMU defaults to starting\n" 4081 " the guest without waiting for gdb to connect; use -S too\n" 4082 " if you want it to not start execution.)\n", 4083 QEMU_ARCH_ALL) 4084SRST 4085``-gdb dev`` 4086 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter 4087 in the System Emulation Users Guide). Note that this option does not pause QEMU 4088 execution -- if you want QEMU to not start the guest until you 4089 connect with gdb and issue a ``continue`` command, you will need to 4090 also pass the ``-S`` option to QEMU. 4091 4092 The most usual configuration is to listen on a local TCP socket:: 4093 4094 -gdb tcp::3117 4095 4096 but you can specify other backends; UDP, pseudo TTY, or even stdio 4097 are all reasonable use cases. For example, a stdio connection 4098 allows you to start QEMU from within gdb and establish the 4099 connection via a pipe: 4100 4101 .. parsed-literal:: 4102 4103 (gdb) target remote | exec |qemu_system| -gdb stdio ... 4104ERST 4105 4106DEF("s", 0, QEMU_OPTION_s, \ 4107 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n", 4108 QEMU_ARCH_ALL) 4109SRST 4110``-s`` 4111 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234 4112 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide). 4113ERST 4114 4115DEF("d", HAS_ARG, QEMU_OPTION_d, \ 4116 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n", 4117 QEMU_ARCH_ALL) 4118SRST 4119``-d item1[,...]`` 4120 Enable logging of specified items. Use '-d help' for a list of log 4121 items. 4122ERST 4123 4124DEF("D", HAS_ARG, QEMU_OPTION_D, \ 4125 "-D logfile output log to logfile (default stderr)\n", 4126 QEMU_ARCH_ALL) 4127SRST 4128``-D logfile`` 4129 Output log in logfile instead of to stderr 4130ERST 4131 4132DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \ 4133 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n", 4134 QEMU_ARCH_ALL) 4135SRST 4136``-dfilter range1[,...]`` 4137 Filter debug output to that relevant to a range of target addresses. 4138 The filter spec can be either start+size, start-size or start..end 4139 where start end and size are the addresses and sizes required. For 4140 example: 4141 4142 :: 4143 4144 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000 4145 4146 Will dump output for any code in the 0x1000 sized block starting at 4147 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and 4148 another 0x1000 sized block starting at 0xffffffc00005f000. 4149ERST 4150 4151DEF("seed", HAS_ARG, QEMU_OPTION_seed, \ 4152 "-seed number seed the pseudo-random number generator\n", 4153 QEMU_ARCH_ALL) 4154SRST 4155``-seed number`` 4156 Force the guest to use a deterministic pseudo-random number 4157 generator, seeded with number. This does not affect crypto routines 4158 within the host. 4159ERST 4160 4161DEF("L", HAS_ARG, QEMU_OPTION_L, \ 4162 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n", 4163 QEMU_ARCH_ALL) 4164SRST 4165``-L path`` 4166 Set the directory for the BIOS, VGA BIOS and keymaps. 4167 4168 To list all the data directories, use ``-L help``. 4169ERST 4170 4171DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ 4172 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) 4173SRST 4174``-bios file`` 4175 Set the filename for the BIOS. 4176ERST 4177 4178DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ 4179 "-enable-kvm enable KVM full virtualization support\n", 4180 QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC | 4181 QEMU_ARCH_RISCV | QEMU_ARCH_S390X) 4182SRST 4183``-enable-kvm`` 4184 Enable KVM full virtualization support. This option is only 4185 available if KVM support is enabled when compiling. 4186ERST 4187 4188DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid, 4189 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL) 4190DEF("xen-attach", 0, QEMU_OPTION_xen_attach, 4191 "-xen-attach attach to existing xen domain\n" 4192 " libxl will use this when starting QEMU\n", 4193 QEMU_ARCH_ALL) 4194DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict, 4195 "-xen-domid-restrict restrict set of available xen operations\n" 4196 " to specified domain id. (Does not affect\n" 4197 " xenpv machine type).\n", 4198 QEMU_ARCH_ALL) 4199SRST 4200``-xen-domid id`` 4201 Specify xen guest domain id (XEN only). 4202 4203``-xen-attach`` 4204 Attach to existing xen domain. libxl will use this when starting 4205 QEMU (XEN only). Restrict set of available xen operations to 4206 specified domain id (XEN only). 4207ERST 4208 4209DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \ 4210 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL) 4211SRST 4212``-no-reboot`` 4213 Exit instead of rebooting. 4214ERST 4215 4216DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \ 4217 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL) 4218SRST 4219``-no-shutdown`` 4220 Don't exit QEMU on guest shutdown, but instead only stop the 4221 emulation. This allows for instance switching to monitor to commit 4222 changes to the disk image. 4223ERST 4224 4225DEF("action", HAS_ARG, QEMU_OPTION_action, 4226 "-action reboot=reset|shutdown\n" 4227 " action when guest reboots [default=reset]\n" 4228 "-action shutdown=poweroff|pause\n" 4229 " action when guest shuts down [default=poweroff]\n" 4230 "-action panic=pause|shutdown|none\n" 4231 " action when guest panics [default=shutdown]\n" 4232 "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" 4233 " action when watchdog fires [default=reset]\n", 4234 QEMU_ARCH_ALL) 4235SRST 4236``-action event=action`` 4237 The action parameter serves to modify QEMU's default behavior when 4238 certain guest events occur. It provides a generic method for specifying the 4239 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown`` 4240 parameters. 4241 4242 Examples: 4243 4244 ``-action panic=none`` 4245 ``-action reboot=shutdown,shutdown=pause`` 4246 ``-watchdog i6300esb -action watchdog=pause`` 4247 4248ERST 4249 4250DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \ 4251 "-loadvm [tag|id]\n" \ 4252 " start right away with a saved state (loadvm in monitor)\n", 4253 QEMU_ARCH_ALL) 4254SRST 4255``-loadvm file`` 4256 Start right away with a saved state (``loadvm`` in monitor) 4257ERST 4258 4259#ifndef _WIN32 4260DEF("daemonize", 0, QEMU_OPTION_daemonize, \ 4261 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL) 4262#endif 4263SRST 4264``-daemonize`` 4265 Daemonize the QEMU process after initialization. QEMU will not 4266 detach from standard IO until it is ready to receive connections on 4267 any of its devices. This option is a useful way for external 4268 programs to launch QEMU without having to cope with initialization 4269 race conditions. 4270ERST 4271 4272DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \ 4273 "-option-rom rom load a file, rom, into the option ROM space\n", 4274 QEMU_ARCH_ALL) 4275SRST 4276``-option-rom file`` 4277 Load the contents of file as an option ROM. This option is useful to 4278 load things like EtherBoot. 4279ERST 4280 4281DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \ 4282 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \ 4283 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n", 4284 QEMU_ARCH_ALL) 4285 4286SRST 4287``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]`` 4288 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at 4289 the current UTC or local time, respectively. ``localtime`` is 4290 required for correct date in MS-DOS or Windows. To start at a 4291 specific point in time, provide datetime in the format 4292 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC. 4293 4294 By default the RTC is driven by the host system time. This allows 4295 using of the RTC as accurate reference clock inside the guest, 4296 specifically if the host time is smoothly following an accurate 4297 external reference clock, e.g. via NTP. If you want to isolate the 4298 guest time from the host, you can set ``clock`` to ``rt`` instead, 4299 which provides a host monotonic clock if host support it. To even 4300 prevent the RTC from progressing during suspension, you can set 4301 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is 4302 recommended especially in icount mode in order to preserve 4303 determinism; however, note that in icount mode the speed of the 4304 virtual clock is variable and can in general differ from the host 4305 clock. 4306 4307 Enable ``driftfix`` (i386 targets only) if you experience time drift 4308 problems, specifically with Windows' ACPI HAL. This option will try 4309 to figure out how many timer interrupts were not processed by the 4310 Windows guest and will re-inject them. 4311ERST 4312 4313DEF("icount", HAS_ARG, QEMU_OPTION_icount, \ 4314 "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \ 4315 " enable virtual instruction counter with 2^N clock ticks per\n" \ 4316 " instruction, enable aligning the host and virtual clocks\n" \ 4317 " or disable real time cpu sleeping, and optionally enable\n" \ 4318 " record-and-replay mode\n", QEMU_ARCH_ALL) 4319SRST 4320``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]`` 4321 Enable virtual instruction counter. The virtual cpu will execute one 4322 instruction every 2^N ns of virtual time. If ``auto`` is specified 4323 then the virtual cpu speed will be automatically adjusted to keep 4324 virtual time within a few seconds of real time. 4325 4326 Note that while this option can give deterministic behavior, it does 4327 not provide cycle accurate emulation. Modern CPUs contain 4328 superscalar out of order cores with complex cache hierarchies. The 4329 number of instructions executed often has little or no correlation 4330 with actual performance. 4331 4332 When the virtual cpu is sleeping, the virtual time will advance at 4333 default speed unless ``sleep=on`` is specified. With 4334 ``sleep=on``, the virtual time will jump to the next timer 4335 deadline instantly whenever the virtual cpu goes to sleep mode and 4336 will not advance if no timer is enabled. This behavior gives 4337 deterministic execution times from the guest point of view. 4338 The default if icount is enabled is ``sleep=off``. 4339 ``sleep=on`` cannot be used together with either ``shift=auto`` 4340 or ``align=on``. 4341 4342 ``align=on`` will activate the delay algorithm which will try to 4343 synchronise the host clock and the virtual clock. The goal is to 4344 have a guest running at the real frequency imposed by the shift 4345 option. Whenever the guest clock is behind the host clock and if 4346 ``align=on`` is specified then we print a message to the user to 4347 inform about the delay. Currently this option does not work when 4348 ``shift`` is ``auto``. Note: The sync algorithm will work for those 4349 shift values for which the guest clock runs ahead of the host clock. 4350 Typically this happens when the shift value is high (how high 4351 depends on the host machine). The default if icount is enabled 4352 is ``align=off``. 4353 4354 When the ``rr`` option is specified deterministic record/replay is 4355 enabled. The ``rrfile=`` option must also be provided to 4356 specify the path to the replay log. In record mode data is written 4357 to this file, and in replay mode it is read back. 4358 If the ``rrsnapshot`` option is given then it specifies a VM snapshot 4359 name. In record mode, a new VM snapshot with the given name is created 4360 at the start of execution recording. In replay mode this option 4361 specifies the snapshot name used to load the initial VM state. 4362ERST 4363 4364DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \ 4365 "-watchdog model\n" \ 4366 " enable virtual hardware watchdog [default=none]\n", 4367 QEMU_ARCH_ALL) 4368SRST 4369``-watchdog model`` 4370 Create a virtual hardware watchdog device. Once enabled (by a guest 4371 action), the watchdog must be periodically polled by an agent inside 4372 the guest or else the guest will be restarted. Choose a model for 4373 which your guest has drivers. 4374 4375 The model is the model of hardware watchdog to emulate. Use 4376 ``-watchdog help`` to list available hardware models. Only one 4377 watchdog can be enabled for a guest. 4378 4379 The following models may be available: 4380 4381 ``ib700`` 4382 iBASE 700 is a very simple ISA watchdog with a single timer. 4383 4384 ``i6300esb`` 4385 Intel 6300ESB I/O controller hub is a much more featureful 4386 PCI-based dual-timer watchdog. 4387 4388 ``diag288`` 4389 A virtual watchdog for s390x backed by the diagnose 288 4390 hypercall (currently KVM only). 4391ERST 4392 4393DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \ 4394 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \ 4395 " action when watchdog fires [default=reset]\n", 4396 QEMU_ARCH_ALL) 4397SRST 4398``-watchdog-action action`` 4399 The action controls what QEMU will do when the watchdog timer 4400 expires. The default is ``reset`` (forcefully reset the guest). 4401 Other possible actions are: ``shutdown`` (attempt to gracefully 4402 shutdown the guest), ``poweroff`` (forcefully poweroff the guest), 4403 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the 4404 guest), ``debug`` (print a debug message and continue), or ``none`` 4405 (do nothing). 4406 4407 Note that the ``shutdown`` action requires that the guest responds 4408 to ACPI signals, which it may not be able to do in the sort of 4409 situations where the watchdog would have expired, and thus 4410 ``-watchdog-action shutdown`` is not recommended for production use. 4411 4412 Examples: 4413 4414 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700`` 4415 4416ERST 4417 4418DEF("echr", HAS_ARG, QEMU_OPTION_echr, \ 4419 "-echr chr set terminal escape character instead of ctrl-a\n", 4420 QEMU_ARCH_ALL) 4421SRST 4422``-echr numeric_ascii_value`` 4423 Change the escape character used for switching to the monitor when 4424 using monitor and serial sharing. The default is ``0x01`` when using 4425 the ``-nographic`` option. ``0x01`` is equal to pressing 4426 ``Control-a``. You can select a different character from the ascii 4427 control keys where 1 through 26 map to Control-a through Control-z. 4428 For instance you could use the either of the following to change the 4429 escape character to Control-t. 4430 4431 ``-echr 0x14``; \ ``-echr 20`` 4432 4433ERST 4434 4435DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \ 4436 "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \ 4437 "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \ 4438 "-incoming unix:socketpath\n" \ 4439 " prepare for incoming migration, listen on\n" \ 4440 " specified protocol and socket address\n" \ 4441 "-incoming fd:fd\n" \ 4442 "-incoming exec:cmdline\n" \ 4443 " accept incoming migration on given file descriptor\n" \ 4444 " or from given external command\n" \ 4445 "-incoming defer\n" \ 4446 " wait for the URI to be specified via migrate_incoming\n", 4447 QEMU_ARCH_ALL) 4448SRST 4449``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]`` 4450 \ 4451``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]`` 4452 Prepare for incoming migration, listen on a given tcp port. 4453 4454``-incoming unix:socketpath`` 4455 Prepare for incoming migration, listen on a given unix socket. 4456 4457``-incoming fd:fd`` 4458 Accept incoming migration from a given filedescriptor. 4459 4460``-incoming exec:cmdline`` 4461 Accept incoming migration as an output from specified external 4462 command. 4463 4464``-incoming defer`` 4465 Wait for the URI to be specified via migrate\_incoming. The monitor 4466 can be used to change settings (such as migration parameters) prior 4467 to issuing the migrate\_incoming to allow the migration to begin. 4468ERST 4469 4470DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \ 4471 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL) 4472SRST 4473``-only-migratable`` 4474 Only allow migratable devices. Devices will not be allowed to enter 4475 an unmigratable state. 4476ERST 4477 4478DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \ 4479 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL) 4480SRST 4481``-nodefaults`` 4482 Don't create default devices. Normally, QEMU sets the default 4483 devices like serial port, parallel port, virtual console, monitor 4484 device, VGA adapter, floppy and CD-ROM drive and others. The 4485 ``-nodefaults`` option will disable all those default devices. 4486ERST 4487 4488#ifndef _WIN32 4489DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \ 4490 "-chroot dir chroot to dir just before starting the VM\n", 4491 QEMU_ARCH_ALL) 4492#endif 4493SRST 4494``-chroot dir`` 4495 Immediately before starting guest execution, chroot to the specified 4496 directory. Especially useful in combination with -runas. 4497ERST 4498 4499#ifndef _WIN32 4500DEF("runas", HAS_ARG, QEMU_OPTION_runas, \ 4501 "-runas user change to user id user just before starting the VM\n" \ 4502 " user can be numeric uid:gid instead\n", 4503 QEMU_ARCH_ALL) 4504#endif 4505SRST 4506``-runas user`` 4507 Immediately before starting guest execution, drop root privileges, 4508 switching to the specified user. 4509ERST 4510 4511DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env, 4512 "-prom-env variable=value\n" 4513 " set OpenBIOS nvram variables\n", 4514 QEMU_ARCH_PPC | QEMU_ARCH_SPARC) 4515SRST 4516``-prom-env variable=value`` 4517 Set OpenBIOS nvram variable to given value (PPC, SPARC only). 4518 4519 :: 4520 4521 qemu-system-sparc -prom-env 'auto-boot?=false' \ 4522 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single' 4523 4524 :: 4525 4526 qemu-system-ppc -prom-env 'auto-boot?=false' \ 4527 -prom-env 'boot-device=hd:2,\yaboot' \ 4528 -prom-env 'boot-args=conf=hd:2,\yaboot.conf' 4529ERST 4530DEF("semihosting", 0, QEMU_OPTION_semihosting, 4531 "-semihosting semihosting mode\n", 4532 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4533 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4534SRST 4535``-semihosting`` 4536 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only). 4537 4538 Note that this allows guest direct access to the host filesystem, so 4539 should only be used with a trusted guest OS. 4540 4541 See the -semihosting-config option documentation for further 4542 information about the facilities this enables. 4543ERST 4544DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, 4545 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \ 4546 " semihosting configuration\n", 4547QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4548QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4549SRST 4550``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]`` 4551 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V 4552 only). 4553 4554 Note that this allows guest direct access to the host filesystem, so 4555 should only be used with a trusted guest OS. 4556 4557 On Arm this implements the standard semihosting API, version 2.0. 4558 4559 On M68K this implements the "ColdFire GDB" interface used by 4560 libgloss. 4561 4562 Xtensa semihosting provides basic file IO calls, such as 4563 open/read/write/seek/select. Tensilica baremetal libc for ISS and 4564 linux platform "sim" use this interface. 4565 4566 On RISC-V this implements the standard semihosting API, version 0.2. 4567 4568 ``target=native|gdb|auto`` 4569 Defines where the semihosting calls will be addressed, to QEMU 4570 (``native``) or to GDB (``gdb``). The default is ``auto``, which 4571 means ``gdb`` during debug sessions and ``native`` otherwise. 4572 4573 ``chardev=str1`` 4574 Send the output to a chardev backend output for native or auto 4575 output when not in gdb 4576 4577 ``arg=str1,arg=str2,...`` 4578 Allows the user to pass input arguments, and can be used 4579 multiple times to build up a list. The old-style 4580 ``-kernel``/``-append`` method of passing a command line is 4581 still supported for backward compatibility. If both the 4582 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are 4583 specified, the former is passed to semihosting as it always 4584 takes precedence. 4585ERST 4586DEF("old-param", 0, QEMU_OPTION_old_param, 4587 "-old-param old param mode\n", QEMU_ARCH_ARM) 4588SRST 4589``-old-param`` 4590 Old param mode (ARM only). 4591ERST 4592 4593DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ 4594 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ 4595 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \ 4596 " Enable seccomp mode 2 system call filter (default 'off').\n" \ 4597 " use 'obsolete' to allow obsolete system calls that are provided\n" \ 4598 " by the kernel, but typically no longer used by modern\n" \ 4599 " C library implementations.\n" \ 4600 " use 'elevateprivileges' to allow or deny the QEMU process ability\n" \ 4601 " to elevate privileges using set*uid|gid system calls.\n" \ 4602 " The value 'children' will deny set*uid|gid system calls for\n" \ 4603 " main QEMU process but will allow forks and execves to run unprivileged\n" \ 4604 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \ 4605 " blocking *fork and execve\n" \ 4606 " use 'resourcecontrol' to disable process affinity and schedular priority\n", 4607 QEMU_ARCH_ALL) 4608SRST 4609``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]`` 4610 Enable Seccomp mode 2 system call filter. 'on' will enable syscall 4611 filtering and 'off' will disable it. The default is 'off'. 4612 4613 ``obsolete=string`` 4614 Enable Obsolete system calls 4615 4616 ``elevateprivileges=string`` 4617 Disable set\*uid\|gid system calls 4618 4619 ``spawn=string`` 4620 Disable \*fork and execve 4621 4622 ``resourcecontrol=string`` 4623 Disable process affinity and schedular priority 4624ERST 4625 4626DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig, 4627 "-readconfig <file>\n" 4628 " read config file\n", QEMU_ARCH_ALL) 4629SRST 4630``-readconfig file`` 4631 Read device configuration from file. This approach is useful when 4632 you want to spawn QEMU process with many command line options but 4633 you don't want to exceed the command line character limit. 4634ERST 4635 4636DEF("no-user-config", 0, QEMU_OPTION_nouserconfig, 4637 "-no-user-config\n" 4638 " do not load default user-provided config files at startup\n", 4639 QEMU_ARCH_ALL) 4640SRST 4641``-no-user-config`` 4642 The ``-no-user-config`` option makes QEMU not load any of the 4643 user-provided config files on sysconfdir. 4644ERST 4645 4646DEF("trace", HAS_ARG, QEMU_OPTION_trace, 4647 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n" 4648 " specify tracing options\n", 4649 QEMU_ARCH_ALL) 4650SRST 4651``-trace [[enable=]pattern][,events=file][,file=file]`` 4652 .. include:: ../qemu-option-trace.rst.inc 4653 4654ERST 4655DEF("plugin", HAS_ARG, QEMU_OPTION_plugin, 4656 "-plugin [file=]<file>[,<argname>=<argvalue>]\n" 4657 " load a plugin\n", 4658 QEMU_ARCH_ALL) 4659SRST 4660``-plugin file=file[,argname=argvalue]`` 4661 Load a plugin. 4662 4663 ``file=file`` 4664 Load the given plugin from a shared library file. 4665 4666 ``argname=argvalue`` 4667 Argument passed to the plugin. (Can be given multiple times.) 4668ERST 4669 4670HXCOMM Internal use 4671DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL) 4672DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL) 4673 4674DEF("msg", HAS_ARG, QEMU_OPTION_msg, 4675 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n" 4676 " control error message format\n" 4677 " timestamp=on enables timestamps (default: off)\n" 4678 " guest-name=on enables guest name prefix but only if\n" 4679 " -name guest option is set (default: off)\n", 4680 QEMU_ARCH_ALL) 4681SRST 4682``-msg [timestamp[=on|off]][,guest-name[=on|off]]`` 4683 Control error message format. 4684 4685 ``timestamp=on|off`` 4686 Prefix messages with a timestamp. Default is off. 4687 4688 ``guest-name=on|off`` 4689 Prefix messages with guest name but only if -name guest option is set 4690 otherwise the option is ignored. Default is off. 4691ERST 4692 4693DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate, 4694 "-dump-vmstate <file>\n" 4695 " Output vmstate information in JSON format to file.\n" 4696 " Use the scripts/vmstate-static-checker.py file to\n" 4697 " check for possible regressions in migration code\n" 4698 " by comparing two such vmstate dumps.\n", 4699 QEMU_ARCH_ALL) 4700SRST 4701``-dump-vmstate file`` 4702 Dump json-encoded vmstate information for current machine type to 4703 file in file 4704ERST 4705 4706DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile, 4707 "-enable-sync-profile\n" 4708 " enable synchronization profiling\n", 4709 QEMU_ARCH_ALL) 4710SRST 4711``-enable-sync-profile`` 4712 Enable synchronization profiling. 4713ERST 4714 4715DEFHEADING() 4716 4717DEFHEADING(Generic object creation:) 4718 4719DEF("object", HAS_ARG, QEMU_OPTION_object, 4720 "-object TYPENAME[,PROP1=VALUE1,...]\n" 4721 " create a new object of type TYPENAME setting properties\n" 4722 " in the order they are specified. Note that the 'id'\n" 4723 " property must be set. These objects are placed in the\n" 4724 " '/objects' path.\n", 4725 QEMU_ARCH_ALL) 4726SRST 4727``-object typename[,prop1=value1,...]`` 4728 Create a new object of type typename setting properties in the order 4729 they are specified. Note that the 'id' property must be set. These 4730 objects are placed in the '/objects' path. 4731 4732 ``-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`` 4733 Creates a memory file backend object, which can be used to back 4734 the guest RAM with huge pages. 4735 4736 The ``id`` parameter is a unique ID that will be used to 4737 reference this memory region in other parameters, e.g. ``-numa``, 4738 ``-device nvdimm``, etc. 4739 4740 The ``size`` option provides the size of the memory region, and 4741 accepts common suffixes, e.g. ``500M``. 4742 4743 The ``mem-path`` provides the path to either a shared memory or 4744 huge page filesystem mount. 4745 4746 The ``share`` boolean option determines whether the memory 4747 region is marked as private to QEMU, or shared. The latter 4748 allows a co-operating external process to access the QEMU memory 4749 region. 4750 4751 The ``share`` is also required for pvrdma devices due to 4752 limitations in the RDMA API provided by Linux. 4753 4754 Setting share=on might affect the ability to configure NUMA 4755 bindings for the memory backend under some circumstances, see 4756 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel 4757 source tree for additional details. 4758 4759 Setting the ``discard-data`` boolean option to on indicates that 4760 file contents can be destroyed when QEMU exits, to avoid 4761 unnecessarily flushing data to the backing file. Note that 4762 ``discard-data`` is only an optimization, and QEMU might not 4763 discard file contents if it aborts unexpectedly or is terminated 4764 using SIGKILL. 4765 4766 The ``merge`` boolean option enables memory merge, also known as 4767 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider 4768 the pages for memory deduplication. 4769 4770 Setting the ``dump`` boolean option to off excludes the memory 4771 from core dumps. This feature is also known as MADV\_DONTDUMP. 4772 4773 The ``prealloc`` boolean option enables memory preallocation. 4774 4775 The ``host-nodes`` option binds the memory range to a list of 4776 NUMA host nodes. 4777 4778 The ``policy`` option sets the NUMA policy to one of the 4779 following values: 4780 4781 ``default`` 4782 default host policy 4783 4784 ``preferred`` 4785 prefer the given host node list for allocation 4786 4787 ``bind`` 4788 restrict memory allocation to the given host node list 4789 4790 ``interleave`` 4791 interleave memory allocations across the given host node 4792 list 4793 4794 The ``align`` option specifies the base address alignment when 4795 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg 4796 ``2M``. Some backend store specified by ``mem-path`` requires an 4797 alignment different than the default one used by QEMU, eg the 4798 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In 4799 such cases, users can specify the required alignment via this 4800 option. 4801 4802 The ``pmem`` option specifies whether the backing file specified 4803 by ``mem-path`` is in host persistent memory that can be 4804 accessed using the SNIA NVM programming model (e.g. Intel 4805 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary 4806 operations to guarantee the persistence of its own writes to 4807 ``mem-path`` (e.g. in vNVDIMM label emulation and live 4808 migration). Also, we will map the backend-file with MAP\_SYNC 4809 flag, which ensures the file metadata is in sync for 4810 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC 4811 requires support from both the host kernel (since Linux kernel 4812 4.15) and the filesystem of ``mem-path`` mounted with DAX 4813 option. 4814 4815 The ``readonly`` option specifies whether the backing file is opened 4816 read-only or read-write (default). 4817 4818 ``-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`` 4819 Creates a memory backend object, which can be used to back the 4820 guest RAM. Memory backend objects offer more control than the 4821 ``-m`` option that is traditionally used to define guest RAM. 4822 Please refer to ``memory-backend-file`` for a description of the 4823 options. 4824 4825 ``-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`` 4826 Creates an anonymous memory file backend object, which allows 4827 QEMU to share the memory with an external process (e.g. when 4828 using vhost-user). The memory is allocated with memfd and 4829 optional sealing. (Linux only) 4830 4831 The ``seal`` option creates a sealed-file, that will block 4832 further resizing the memory ('on' by default). 4833 4834 The ``hugetlb`` option specify the file to be created resides in 4835 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction 4836 with the ``hugetlb`` option, the ``hugetlbsize`` option specify 4837 the hugetlb page size on systems that support multiple hugetlb 4838 page sizes (it must be a power of 2 value supported by the 4839 system). 4840 4841 In some versions of Linux, the ``hugetlb`` option is 4842 incompatible with the ``seal`` option (requires at least Linux 4843 4.16). 4844 4845 Please refer to ``memory-backend-file`` for a description of the 4846 other options. 4847 4848 The ``share`` boolean option is on by default with memfd. 4849 4850 ``-object rng-builtin,id=id`` 4851 Creates a random number generator backend which obtains entropy 4852 from QEMU builtin functions. The ``id`` parameter is a unique ID 4853 that will be used to reference this entropy backend from the 4854 ``virtio-rng`` device. By default, the ``virtio-rng`` device 4855 uses this RNG backend. 4856 4857 ``-object rng-random,id=id,filename=/dev/random`` 4858 Creates a random number generator backend which obtains entropy 4859 from a device on the host. The ``id`` parameter is a unique ID 4860 that will be used to reference this entropy backend from the 4861 ``virtio-rng`` device. The ``filename`` parameter specifies 4862 which file to obtain entropy from and if omitted defaults to 4863 ``/dev/urandom``. 4864 4865 ``-object rng-egd,id=id,chardev=chardevid`` 4866 Creates a random number generator backend which obtains entropy 4867 from an external daemon running on the host. The ``id`` 4868 parameter is a unique ID that will be used to reference this 4869 entropy backend from the ``virtio-rng`` device. The ``chardev`` 4870 parameter is the unique ID of a character device backend that 4871 provides the connection to the RNG daemon. 4872 4873 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off`` 4874 Creates a TLS anonymous credentials object, which can be used to 4875 provide TLS support on network backends. The ``id`` parameter is 4876 a unique ID which network backends will use to access the 4877 credentials. The ``endpoint`` is either ``server`` or ``client`` 4878 depending on whether the QEMU network backend that uses the 4879 credentials will be acting as a client or as a server. If 4880 ``verify-peer`` is enabled (the default) then once the handshake 4881 is completed, the peer credentials will be verified, though this 4882 is a no-op for anonymous credentials. 4883 4884 The dir parameter tells QEMU where to find the credential files. 4885 For server endpoints, this directory may contain a file 4886 dh-params.pem providing diffie-hellman parameters to use for the 4887 TLS server. If the file is missing, QEMU will generate a set of 4888 DH parameters at startup. This is a computationally expensive 4889 operation that consumes random pool entropy, so it is 4890 recommended that a persistent set of parameters be generated 4891 upfront and saved. 4892 4893 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]`` 4894 Creates a TLS Pre-Shared Keys (PSK) credentials object, which 4895 can be used to provide TLS support on network backends. The 4896 ``id`` parameter is a unique ID which network backends will use 4897 to access the credentials. The ``endpoint`` is either ``server`` 4898 or ``client`` depending on whether the QEMU network backend that 4899 uses the credentials will be acting as a client or as a server. 4900 For clients only, ``username`` is the username which will be 4901 sent to the server. If omitted it defaults to "qemu". 4902 4903 The dir parameter tells QEMU where to find the keys file. It is 4904 called "dir/keys.psk" and contains "username:key" pairs. This 4905 file can most easily be created using the GnuTLS ``psktool`` 4906 program. 4907 4908 For server endpoints, dir may also contain a file dh-params.pem 4909 providing diffie-hellman parameters to use for the TLS server. 4910 If the file is missing, QEMU will generate a set of DH 4911 parameters at startup. This is a computationally expensive 4912 operation that consumes random pool entropy, so it is 4913 recommended that a persistent set of parameters be generated up 4914 front and saved. 4915 4916 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id`` 4917 Creates a TLS anonymous credentials object, which can be used to 4918 provide TLS support on network backends. The ``id`` parameter is 4919 a unique ID which network backends will use to access the 4920 credentials. The ``endpoint`` is either ``server`` or ``client`` 4921 depending on whether the QEMU network backend that uses the 4922 credentials will be acting as a client or as a server. If 4923 ``verify-peer`` is enabled (the default) then once the handshake 4924 is completed, the peer credentials will be verified. With x509 4925 certificates, this implies that the clients must be provided 4926 with valid client certificates too. 4927 4928 The dir parameter tells QEMU where to find the credential files. 4929 For server endpoints, this directory may contain a file 4930 dh-params.pem providing diffie-hellman parameters to use for the 4931 TLS server. If the file is missing, QEMU will generate a set of 4932 DH parameters at startup. This is a computationally expensive 4933 operation that consumes random pool entropy, so it is 4934 recommended that a persistent set of parameters be generated 4935 upfront and saved. 4936 4937 For x509 certificate credentials the directory will contain 4938 further files providing the x509 certificates. The certificates 4939 must be stored in PEM format, in filenames ca-cert.pem, 4940 ca-crl.pem (optional), server-cert.pem (only servers), 4941 server-key.pem (only servers), client-cert.pem (only clients), 4942 and client-key.pem (only clients). 4943 4944 For the server-key.pem and client-key.pem files which contain 4945 sensitive private keys, it is possible to use an encrypted 4946 version by providing the passwordid parameter. This provides the 4947 ID of a previously created ``secret`` object containing the 4948 password for decryption. 4949 4950 The priority parameter allows to override the global default 4951 priority used by gnutls. This can be useful if the system 4952 administrator needs to use a weaker set of crypto priorities for 4953 QEMU without potentially forcing the weakness onto all 4954 applications. Or conversely if one wants wants a stronger 4955 default for QEMU than for all other applications, they can do 4956 this through this parameter. Its format is a gnutls priority 4957 string as described at 4958 https://gnutls.org/manual/html_node/Priority-Strings.html. 4959 4960 ``-object tls-cipher-suites,id=id,priority=priority`` 4961 Creates a TLS cipher suites object, which can be used to control 4962 the TLS cipher/protocol algorithms that applications are permitted 4963 to use. 4964 4965 The ``id`` parameter is a unique ID which frontends will use to 4966 access the ordered list of permitted TLS cipher suites from the 4967 host. 4968 4969 The ``priority`` parameter allows to override the global default 4970 priority used by gnutls. This can be useful if the system 4971 administrator needs to use a weaker set of crypto priorities for 4972 QEMU without potentially forcing the weakness onto all 4973 applications. Or conversely if one wants wants a stronger 4974 default for QEMU than for all other applications, they can do 4975 this through this parameter. Its format is a gnutls priority 4976 string as described at 4977 https://gnutls.org/manual/html_node/Priority-Strings.html. 4978 4979 An example of use of this object is to control UEFI HTTPS Boot. 4980 The tls-cipher-suites object exposes the ordered list of permitted 4981 TLS cipher suites from the host side to the guest firmware, via 4982 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER 4983 objects. The firmware uses the IANA_TLS_CIPHER array for configuring 4984 guest-side TLS. 4985 4986 In the following example, the priority at which the host-side policy 4987 is retrieved is given by the ``priority`` property. 4988 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to 4989 refer to /etc/crypto-policies/back-ends/gnutls.config. 4990 4991 .. parsed-literal:: 4992 4993 # |qemu_system| \\ 4994 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\ 4995 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0 4996 4997 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]`` 4998 Interval t can't be 0, this filter batches the packet delivery: 4999 all packets arriving in a given interval on netdev netdevid are 5000 delayed until the end of the interval. Interval is in 5001 microseconds. ``status`` is optional that indicate whether the 5002 netfilter is on (enabled) or off (disabled), the default status 5003 for netfilter will be 'on'. 5004 5005 queue all\|rx\|tx is an option that can be applied to any 5006 netfilter. 5007 5008 ``all``: the filter is attached both to the receive and the 5009 transmit queue of the netdev (default). 5010 5011 ``rx``: the filter is attached to the receive queue of the 5012 netdev, where it will receive packets sent to the netdev. 5013 5014 ``tx``: the filter is attached to the transmit queue of the 5015 netdev, where it will receive packets sent by the netdev. 5016 5017 position head\|tail\|id=<id> is an option to specify where the 5018 filter should be inserted in the filter list. It can be applied 5019 to any netfilter. 5020 5021 ``head``: the filter is inserted at the head of the filter list, 5022 before any existing filters. 5023 5024 ``tail``: the filter is inserted at the tail of the filter list, 5025 behind any existing filters (default). 5026 5027 ``id=<id>``: the filter is inserted before or behind the filter 5028 specified by <id>, see the insert option below. 5029 5030 insert behind\|before is an option to specify where to insert 5031 the new filter relative to the one specified with 5032 position=id=<id>. It can be applied to any netfilter. 5033 5034 ``before``: insert before the specified filter. 5035 5036 ``behind``: insert behind the specified filter (default). 5037 5038 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5039 filter-mirror on netdev netdevid,mirror net packet to 5040 chardevchardevid, if it has the vnet\_hdr\_support flag, 5041 filter-mirror will mirror packet with vnet\_hdr\_len. 5042 5043 ``-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]`` 5044 filter-redirector on netdev netdevid,redirect filter's net 5045 packet to chardev chardevid,and redirect indev's packet to 5046 filter.if it has the vnet\_hdr\_support flag, filter-redirector 5047 will redirect packet with vnet\_hdr\_len. Create a 5048 filter-redirector we need to differ outdev id from indev id, id 5049 can not be the same. we can just use indev or outdev, but at 5050 least one of indev or outdev need to be specified. 5051 5052 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5053 Filter-rewriter is a part of COLO project.It will rewrite tcp 5054 packet to secondary from primary to keep secondary tcp 5055 connection,and rewrite tcp packet to primary from secondary make 5056 tcp packet can be handled by client.if it has the 5057 vnet\_hdr\_support flag, we can parse packet with vnet header. 5058 5059 usage: colo secondary: -object 5060 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object 5061 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object 5062 filter-rewriter,id=rew0,netdev=hn0,queue=all 5063 5064 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]`` 5065 Dump the network traffic on netdev dev to the file specified by 5066 filename. At most len bytes (64k by default) per packet are 5067 stored. The file format is libpcap, so it can be analyzed with 5068 tools such as tcpdump or Wireshark. 5069 5070 ``-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}]`` 5071 Colo-compare gets packet from primary\_in chardevid and 5072 secondary\_in, then compare whether the payload of primary packet 5073 and secondary packet are the same. If same, it will output 5074 primary packet to out\_dev, else it will notify COLO-framework to do 5075 checkpoint and send primary packet to out\_dev. In order to 5076 improve efficiency, we need to put the task of comparison in 5077 another iothread. If it has the vnet\_hdr\_support flag, 5078 colo compare will send/recv packet with vnet\_hdr\_len. 5079 The compare\_timeout=@var{ms} determines the maximum time of the 5080 colo-compare hold the packet. The expired\_scan\_cycle=@var{ms} 5081 is to set the period of scanning expired primary node network packets. 5082 The max\_queue\_size=@var{size} is to set the max compare queue 5083 size depend on user environment. 5084 If user want to use Xen COLO, need to add the notify\_dev to 5085 notify Xen colo-frame to do checkpoint. 5086 5087 COLO-compare must be used with the help of filter-mirror, 5088 filter-redirector and filter-rewriter. 5089 5090 :: 5091 5092 KVM COLO 5093 5094 primary: 5095 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5096 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5097 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5098 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5099 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5100 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5101 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5102 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5103 -object iothread,id=iothread1 5104 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5105 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5106 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5107 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1 5108 5109 secondary: 5110 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5111 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5112 -chardev socket,id=red0,host=3.3.3.3,port=9003 5113 -chardev socket,id=red1,host=3.3.3.3,port=9004 5114 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5115 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5116 5117 5118 Xen COLO 5119 5120 primary: 5121 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5122 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5123 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5124 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5125 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5126 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5127 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5128 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5129 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server=on,wait=off 5130 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5131 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5132 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5133 -object iothread,id=iothread1 5134 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1 5135 5136 secondary: 5137 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5138 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5139 -chardev socket,id=red0,host=3.3.3.3,port=9003 5140 -chardev socket,id=red1,host=3.3.3.3,port=9004 5141 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5142 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5143 5144 If you want to know the detail of above command line, you can 5145 read the colo-compare git log. 5146 5147 ``-object cryptodev-backend-builtin,id=id[,queues=queues]`` 5148 Creates a cryptodev backend which executes crypto opreation from 5149 the QEMU cipher APIS. The id parameter is a unique ID that will 5150 be used to reference this cryptodev backend from the 5151 ``virtio-crypto`` device. The queues parameter is optional, 5152 which specify the queue number of cryptodev backend, the default 5153 of queues is 1. 5154 5155 .. parsed-literal:: 5156 5157 # |qemu_system| \\ 5158 [...] \\ 5159 -object cryptodev-backend-builtin,id=cryptodev0 \\ 5160 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5161 [...] 5162 5163 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]`` 5164 Creates a vhost-user cryptodev backend, backed by a chardev 5165 chardevid. The id parameter is a unique ID that will be used to 5166 reference this cryptodev backend from the ``virtio-crypto`` 5167 device. The chardev should be a unix domain socket backed one. 5168 The vhost-user uses a specifically defined protocol to pass 5169 vhost ioctl replacement messages to an application on the other 5170 end of the socket. The queues parameter is optional, which 5171 specify the queue number of cryptodev backend for multiqueue 5172 vhost-user, the default of queues is 1. 5173 5174 .. parsed-literal:: 5175 5176 # |qemu_system| \\ 5177 [...] \\ 5178 -chardev socket,id=chardev0,path=/path/to/socket \\ 5179 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\ 5180 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5181 [...] 5182 5183 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]`` 5184 \ 5185 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]`` 5186 Defines a secret to store a password, encryption key, or some 5187 other sensitive data. The sensitive data can either be passed 5188 directly via the data parameter, or indirectly via the file 5189 parameter. Using the data parameter is insecure unless the 5190 sensitive data is encrypted. 5191 5192 The sensitive data can be provided in raw format (the default), 5193 or base64. When encoded as JSON, the raw format only supports 5194 valid UTF-8 characters, so base64 is recommended for sending 5195 binary data. QEMU will convert from which ever format is 5196 provided to the format it needs internally. eg, an RBD password 5197 can be provided in raw format, even though it will be base64 5198 encoded when passed onto the RBD sever. 5199 5200 For added protection, it is possible to encrypt the data 5201 associated with a secret using the AES-256-CBC cipher. Use of 5202 encryption is indicated by providing the keyid and iv 5203 parameters. The keyid parameter provides the ID of a previously 5204 defined secret that contains the AES-256 decryption key. This 5205 key should be 32-bytes long and be base64 encoded. The iv 5206 parameter provides the random initialization vector used for 5207 encryption of this particular secret and should be a base64 5208 encrypted string of the 16-byte IV. 5209 5210 The simplest (insecure) usage is to provide the secret inline 5211 5212 .. parsed-literal:: 5213 5214 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw 5215 5216 The simplest secure usage is to provide the secret via a file 5217 5218 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object 5219 secret,id=sec0,file=mypasswd.txt,format=raw 5220 5221 For greater security, AES-256-CBC should be used. To illustrate 5222 usage, consider the openssl command line tool which can encrypt 5223 the data. Note that when encrypting, the plaintext must be 5224 padded to the cipher block size (32 bytes) using the standard 5225 PKCS#5/6 compatible padding algorithm. 5226 5227 First a master key needs to be created in base64 encoding: 5228 5229 :: 5230 5231 # openssl rand -base64 32 > key.b64 5232 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"') 5233 5234 Each secret to be encrypted needs to have a random 5235 initialization vector generated. These do not need to be kept 5236 secret 5237 5238 :: 5239 5240 # openssl rand -base64 16 > iv.b64 5241 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"') 5242 5243 The secret to be defined can now be encrypted, in this case 5244 we're telling openssl to base64 encode the result, but it could 5245 be left as raw bytes if desired. 5246 5247 :: 5248 5249 # SECRET=$(printf "letmein" | 5250 openssl enc -aes-256-cbc -a -K $KEY -iv $IV) 5251 5252 When launching QEMU, create a master secret pointing to 5253 ``key.b64`` and specify that to be used to decrypt the user 5254 password. Pass the contents of ``iv.b64`` to the second secret 5255 5256 .. parsed-literal:: 5257 5258 # |qemu_system| \\ 5259 -object secret,id=secmaster0,format=base64,file=key.b64 \\ 5260 -object secret,id=sec0,keyid=secmaster0,format=base64,\\ 5261 data=$SECRET,iv=$(<iv.b64) 5262 5263 ``-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,kernel-hashes=on|off]`` 5264 Create a Secure Encrypted Virtualization (SEV) guest object, 5265 which can be used to provide the guest memory encryption support 5266 on AMD processors. 5267 5268 When memory encryption is enabled, one of the physical address 5269 bit (aka the C-bit) is utilized to mark if a memory page is 5270 protected. The ``cbitpos`` is used to provide the C-bit 5271 position. The C-bit position is Host family dependent hence user 5272 must provide this value. On EPYC, the value should be 47. 5273 5274 When memory encryption is enabled, we loose certain bits in 5275 physical address space. The ``reduced-phys-bits`` is used to 5276 provide the number of bits we loose in physical address space. 5277 Similar to C-bit, the value is Host family dependent. On EPYC, 5278 the value should be 5. 5279 5280 The ``sev-device`` provides the device file to use for 5281 communicating with the SEV firmware running inside AMD Secure 5282 Processor. The default device is '/dev/sev'. If hardware 5283 supports memory encryption then /dev/sev devices are created by 5284 CCP driver. 5285 5286 The ``policy`` provides the guest policy to be enforced by the 5287 SEV firmware and restrict what configuration and operational 5288 commands can be performed on this guest by the hypervisor. The 5289 policy should be provided by the guest owner and is bound to the 5290 guest and cannot be changed throughout the lifetime of the 5291 guest. The default is 0. 5292 5293 If guest ``policy`` allows sharing the key with another SEV 5294 guest then ``handle`` can be use to provide handle of the guest 5295 from which to share the key. 5296 5297 The ``dh-cert-file`` and ``session-file`` provides the guest 5298 owner's Public Diffie-Hillman key defined in SEV spec. The PDH 5299 and session parameters are used for establishing a cryptographic 5300 session with the guest owner to negotiate keys used for 5301 attestation. The file must be encoded in base64. 5302 5303 The ``kernel-hashes`` adds the hashes of given kernel/initrd/ 5304 cmdline to a designated guest firmware page for measured Linux 5305 boot with -kernel. The default is off. (Since 6.2) 5306 5307 e.g to launch a SEV guest 5308 5309 .. parsed-literal:: 5310 5311 # |qemu_system_x86| \\ 5312 ...... \\ 5313 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\ 5314 -machine ...,memory-encryption=sev0 \\ 5315 ..... 5316 5317 ``-object authz-simple,id=id,identity=string`` 5318 Create an authorization object that will control access to 5319 network services. 5320 5321 The ``identity`` parameter is identifies the user and its format 5322 depends on the network service that authorization object is 5323 associated with. For authorizing based on TLS x509 certificates, 5324 the identity must be the x509 distinguished name. Note that care 5325 must be taken to escape any commas in the distinguished name. 5326 5327 An example authorization object to validate a x509 distinguished 5328 name would look like: 5329 5330 .. parsed-literal:: 5331 5332 # |qemu_system| \\ 5333 ... \\ 5334 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\ 5335 ... 5336 5337 Note the use of quotes due to the x509 distinguished name 5338 containing whitespace, and escaping of ','. 5339 5340 ``-object authz-listfile,id=id,filename=path,refresh=on|off`` 5341 Create an authorization object that will control access to 5342 network services. 5343 5344 The ``filename`` parameter is the fully qualified path to a file 5345 containing the access control list rules in JSON format. 5346 5347 An example set of rules that match against SASL usernames might 5348 look like: 5349 5350 :: 5351 5352 { 5353 "rules": [ 5354 { "match": "fred", "policy": "allow", "format": "exact" }, 5355 { "match": "bob", "policy": "allow", "format": "exact" }, 5356 { "match": "danb", "policy": "deny", "format": "glob" }, 5357 { "match": "dan*", "policy": "allow", "format": "exact" }, 5358 ], 5359 "policy": "deny" 5360 } 5361 5362 When checking access the object will iterate over all the rules 5363 and the first rule to match will have its ``policy`` value 5364 returned as the result. If no rules match, then the default 5365 ``policy`` value is returned. 5366 5367 The rules can either be an exact string match, or they can use 5368 the simple UNIX glob pattern matching to allow wildcards to be 5369 used. 5370 5371 If ``refresh`` is set to true the file will be monitored and 5372 automatically reloaded whenever its content changes. 5373 5374 As with the ``authz-simple`` object, the format of the identity 5375 strings being matched depends on the network service, but is 5376 usually a TLS x509 distinguished name, or a SASL username. 5377 5378 An example authorization object to validate a SASL username 5379 would look like: 5380 5381 .. parsed-literal:: 5382 5383 # |qemu_system| \\ 5384 ... \\ 5385 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\ 5386 ... 5387 5388 ``-object authz-pam,id=id,service=string`` 5389 Create an authorization object that will control access to 5390 network services. 5391 5392 The ``service`` parameter provides the name of a PAM service to 5393 use for authorization. It requires that a file 5394 ``/etc/pam.d/service`` exist to provide the configuration for 5395 the ``account`` subsystem. 5396 5397 An example authorization object to validate a TLS x509 5398 distinguished name would look like: 5399 5400 .. parsed-literal:: 5401 5402 # |qemu_system| \\ 5403 ... \\ 5404 -object authz-pam,id=auth0,service=qemu-vnc \\ 5405 ... 5406 5407 There would then be a corresponding config file for PAM at 5408 ``/etc/pam.d/qemu-vnc`` that contains: 5409 5410 :: 5411 5412 account requisite pam_listfile.so item=user sense=allow \ 5413 file=/etc/qemu/vnc.allow 5414 5415 Finally the ``/etc/qemu/vnc.allow`` file would contain the list 5416 of x509 distingished names that are permitted access 5417 5418 :: 5419 5420 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB 5421 5422 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch`` 5423 Creates a dedicated event loop thread that devices can be 5424 assigned to. This is known as an IOThread. By default device 5425 emulation happens in vCPU threads or the main event loop thread. 5426 This can become a scalability bottleneck. IOThreads allow device 5427 emulation and I/O to run on other host CPUs. 5428 5429 The ``id`` parameter is a unique ID that will be used to 5430 reference this IOThread from ``-device ...,iothread=id``. 5431 Multiple devices can be assigned to an IOThread. Note that not 5432 all devices support an ``iothread`` parameter. 5433 5434 The ``query-iothreads`` QMP command lists IOThreads and reports 5435 their thread IDs so that the user can configure host CPU 5436 pinning/affinity. 5437 5438 IOThreads use an adaptive polling algorithm to reduce event loop 5439 latency. Instead of entering a blocking system call to monitor 5440 file descriptors and then pay the cost of being woken up when an 5441 event occurs, the polling algorithm spins waiting for events for 5442 a short time. The algorithm's default parameters are suitable 5443 for many cases but can be adjusted based on knowledge of the 5444 workload and/or host device latency. 5445 5446 The ``poll-max-ns`` parameter is the maximum number of 5447 nanoseconds to busy wait for events. Polling can be disabled by 5448 setting this value to 0. 5449 5450 The ``poll-grow`` parameter is the multiplier used to increase 5451 the polling time when the algorithm detects it is missing events 5452 due to not polling long enough. 5453 5454 The ``poll-shrink`` parameter is the divisor used to decrease 5455 the polling time when the algorithm detects it is spending too 5456 long polling without encountering events. 5457 5458 The ``aio-max-batch`` parameter is the maximum number of requests 5459 in a batch for the AIO engine, 0 means that the engine will use 5460 its default. 5461 5462 The IOThread parameters can be modified at run-time using the 5463 ``qom-set`` command (where ``iothread1`` is the IOThread's 5464 ``id``): 5465 5466 :: 5467 5468 (qemu) qom-set /objects/iothread1 poll-max-ns 100000 5469ERST 5470 5471 5472HXCOMM This is the last statement. Insert new options before this line! 5473 5474#undef DEF 5475#undef DEFHEADING 5476#undef ARCHHEADING 5477
