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 2100DEF("spice", HAS_ARG, QEMU_OPTION_spice, 2101 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n" 2102 " [,x509-key-file=<file>][,x509-key-password=<file>]\n" 2103 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n" 2104 " [,x509-dh-key-file=<file>][,addr=addr]\n" 2105 " [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n" 2106 " [,tls-ciphers=<list>]\n" 2107 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n" 2108 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n" 2109 " [,sasl=on|off][,disable-ticketing=on|off]\n" 2110 " [,password=<string>][,password-secret=<secret-id>]\n" 2111 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n" 2112 " [,jpeg-wan-compression=[auto|never|always]]\n" 2113 " [,zlib-glz-wan-compression=[auto|never|always]]\n" 2114 " [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n" 2115 " [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n" 2116 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n" 2117 " [,gl=[on|off]][,rendernode=<file>]\n" 2118 " enable spice\n" 2119 " at least one of {port, tls-port} is mandatory\n", 2120 QEMU_ARCH_ALL) 2121SRST 2122``-spice option[,option[,...]]`` 2123 Enable the spice remote desktop protocol. Valid options are 2124 2125 ``port=<nr>`` 2126 Set the TCP port spice is listening on for plaintext channels. 2127 2128 ``addr=<addr>`` 2129 Set the IP address spice is listening on. Default is any 2130 address. 2131 2132 ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off`` 2133 Force using the specified IP version. 2134 2135 ``password=<string>`` 2136 Set the password you need to authenticate. 2137 2138 This option is deprecated and insecure because it leaves the 2139 password visible in the process listing. Use ``password-secret`` 2140 instead. 2141 2142 ``password-secret=<secret-id>`` 2143 Set the ID of the ``secret`` object containing the password 2144 you need to authenticate. 2145 2146 ``sasl=on|off`` 2147 Require that the client use SASL to authenticate with the spice. 2148 The exact choice of authentication method used is controlled 2149 from the system / user's SASL configuration file for the 'qemu' 2150 service. This is typically found in /etc/sasl2/qemu.conf. If 2151 running QEMU as an unprivileged user, an environment variable 2152 SASL\_CONF\_PATH can be used to make it search alternate 2153 locations for the service config. While some SASL auth methods 2154 can also provide data encryption (eg GSSAPI), it is recommended 2155 that SASL always be combined with the 'tls' and 'x509' settings 2156 to enable use of SSL and server certificates. This ensures a 2157 data encryption preventing compromise of authentication 2158 credentials. 2159 2160 ``disable-ticketing=on|off`` 2161 Allow client connects without authentication. 2162 2163 ``disable-copy-paste=on|off`` 2164 Disable copy paste between the client and the guest. 2165 2166 ``disable-agent-file-xfer=on|off`` 2167 Disable spice-vdagent based file-xfer between the client and the 2168 guest. 2169 2170 ``tls-port=<nr>`` 2171 Set the TCP port spice is listening on for encrypted channels. 2172 2173 ``x509-dir=<dir>`` 2174 Set the x509 file directory. Expects same filenames as -vnc 2175 $display,x509=$dir 2176 2177 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>`` 2178 The x509 file names can also be configured individually. 2179 2180 ``tls-ciphers=<list>`` 2181 Specify which ciphers to use. 2182 2183 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]`` 2184 Force specific channel to be used with or without TLS 2185 encryption. The options can be specified multiple times to 2186 configure multiple channels. The special name "default" can be 2187 used to set the default mode. For channels which are not 2188 explicitly forced into one mode the spice client is allowed to 2189 pick tls/plaintext as he pleases. 2190 2191 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]`` 2192 Configure image compression (lossless). Default is auto\_glz. 2193 2194 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]`` 2195 Configure wan image compression (lossy for slow links). Default 2196 is auto. 2197 2198 ``streaming-video=[off|all|filter]`` 2199 Configure video stream detection. Default is off. 2200 2201 ``agent-mouse=[on|off]`` 2202 Enable/disable passing mouse events via vdagent. Default is on. 2203 2204 ``playback-compression=[on|off]`` 2205 Enable/disable audio stream compression (using celt 0.5.1). 2206 Default is on. 2207 2208 ``seamless-migration=[on|off]`` 2209 Enable/disable spice seamless migration. Default is off. 2210 2211 ``gl=[on|off]`` 2212 Enable/disable OpenGL context. Default is off. 2213 2214 ``rendernode=<file>`` 2215 DRM render node for OpenGL rendering. If not specified, it will 2216 pick the first available. (Since 2.9) 2217ERST 2218 2219DEF("portrait", 0, QEMU_OPTION_portrait, 2220 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n", 2221 QEMU_ARCH_ALL) 2222SRST 2223``-portrait`` 2224 Rotate graphical output 90 deg left (only PXA LCD). 2225ERST 2226 2227DEF("rotate", HAS_ARG, QEMU_OPTION_rotate, 2228 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n", 2229 QEMU_ARCH_ALL) 2230SRST 2231``-rotate deg`` 2232 Rotate graphical output some deg left (only PXA LCD). 2233ERST 2234 2235DEF("vga", HAS_ARG, QEMU_OPTION_vga, 2236 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n" 2237 " select video card type\n", QEMU_ARCH_ALL) 2238SRST 2239``-vga type`` 2240 Select type of VGA card to emulate. Valid values for type are 2241 2242 ``cirrus`` 2243 Cirrus Logic GD5446 Video card. All Windows versions starting 2244 from Windows 95 should recognize and use this graphic card. For 2245 optimal performances, use 16 bit color depth in the guest and 2246 the host OS. (This card was the default before QEMU 2.2) 2247 2248 ``std`` 2249 Standard VGA card with Bochs VBE extensions. If your guest OS 2250 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if 2251 you want to use high resolution modes (>= 1280x1024x16) then you 2252 should use this option. (This card is the default since QEMU 2253 2.2) 2254 2255 ``vmware`` 2256 VMWare SVGA-II compatible adapter. Use it if you have 2257 sufficiently recent XFree86/XOrg server or Windows guest with a 2258 driver for this card. 2259 2260 ``qxl`` 2261 QXL paravirtual graphic card. It is VGA compatible (including 2262 VESA 2.0 VBE support). Works best with qxl guest drivers 2263 installed though. Recommended choice when using the spice 2264 protocol. 2265 2266 ``tcx`` 2267 (sun4m only) Sun TCX framebuffer. This is the default 2268 framebuffer for sun4m machines and offers both 8-bit and 24-bit 2269 colour depths at a fixed resolution of 1024x768. 2270 2271 ``cg3`` 2272 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit 2273 framebuffer for sun4m machines available in both 1024x768 2274 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people 2275 wishing to run older Solaris versions. 2276 2277 ``virtio`` 2278 Virtio VGA card. 2279 2280 ``none`` 2281 Disable VGA card. 2282ERST 2283 2284DEF("full-screen", 0, QEMU_OPTION_full_screen, 2285 "-full-screen start in full screen\n", QEMU_ARCH_ALL) 2286SRST 2287``-full-screen`` 2288 Start in full screen. 2289ERST 2290 2291DEF("g", HAS_ARG, QEMU_OPTION_g , 2292 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n", 2293 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K) 2294SRST 2295``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]`` 2296 Set the initial graphical resolution and depth (PPC, SPARC only). 2297 2298 For PPC the default is 800x600x32. 2299 2300 For SPARC with the TCX graphics device, the default is 1024x768x8 2301 with the option of 1024x768x24. For cgthree, the default is 2302 1024x768x8 with the option of 1152x900x8 for people who wish to use 2303 OBP. 2304ERST 2305 2306DEF("vnc", HAS_ARG, QEMU_OPTION_vnc , 2307 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL) 2308SRST 2309``-vnc display[,option[,option[,...]]]`` 2310 Normally, if QEMU is compiled with graphical window support, it 2311 displays output such as guest graphics, guest console, and the QEMU 2312 monitor in a window. With this option, you can have QEMU listen on 2313 VNC display display and redirect the VGA display over the VNC 2314 session. It is very useful to enable the usb tablet device when 2315 using this option (option ``-device usb-tablet``). When using the 2316 VNC display, you must use the ``-k`` parameter to set the keyboard 2317 layout if you are not using en-us. Valid syntax for the display is 2318 2319 ``to=L`` 2320 With this option, QEMU will try next available VNC displays, 2321 until the number L, if the origianlly defined "-vnc display" is 2322 not available, e.g. port 5900+display is already used by another 2323 application. By default, to=0. 2324 2325 ``host:d`` 2326 TCP connections will only be allowed from host on display d. By 2327 convention the TCP port is 5900+d. Optionally, host can be 2328 omitted in which case the server will accept connections from 2329 any host. 2330 2331 ``unix:path`` 2332 Connections will be allowed over UNIX domain sockets where path 2333 is the location of a unix socket to listen for connections on. 2334 2335 ``none`` 2336 VNC is initialized but not started. The monitor ``change`` 2337 command can be used to later start the VNC server. 2338 2339 Following the display value there may be one or more option flags 2340 separated by commas. Valid options are 2341 2342 ``reverse=on|off`` 2343 Connect to a listening VNC client via a "reverse" connection. 2344 The client is specified by the display. For reverse network 2345 connections (host:d,``reverse``), the d argument is a TCP port 2346 number, not a display number. 2347 2348 ``websocket=on|off`` 2349 Opens an additional TCP listening port dedicated to VNC 2350 Websocket connections. If a bare websocket option is given, the 2351 Websocket port is 5700+display. An alternative port can be 2352 specified with the syntax ``websocket``\ =port. 2353 2354 If host is specified connections will only be allowed from this 2355 host. It is possible to control the websocket listen address 2356 independently, using the syntax ``websocket``\ =host:port. 2357 2358 If no TLS credentials are provided, the websocket connection 2359 runs in unencrypted mode. If TLS credentials are provided, the 2360 websocket connection requires encrypted client connections. 2361 2362 ``password=on|off`` 2363 Require that password based authentication is used for client 2364 connections. 2365 2366 The password must be set separately using the ``set_password`` 2367 command in the :ref:`QEMU monitor`. The 2368 syntax to change your password is: 2369 ``set_password <protocol> <password>`` where <protocol> could be 2370 either "vnc" or "spice". 2371 2372 If you would like to change <protocol> password expiration, you 2373 should use ``expire_password <protocol> <expiration-time>`` 2374 where expiration time could be one of the following options: 2375 now, never, +seconds or UNIX time of expiration, e.g. +60 to 2376 make password expire in 60 seconds, or 1335196800 to make 2377 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for 2378 this date and time). 2379 2380 You can also use keywords "now" or "never" for the expiration 2381 time to allow <protocol> password to expire immediately or never 2382 expire. 2383 2384 ``password-secret=<secret-id>`` 2385 Require that password based authentication is used for client 2386 connections, using the password provided by the ``secret`` 2387 object identified by ``secret-id``. 2388 2389 ``tls-creds=ID`` 2390 Provides the ID of a set of TLS credentials to use to secure the 2391 VNC server. They will apply to both the normal VNC server socket 2392 and the websocket socket (if enabled). Setting TLS credentials 2393 will cause the VNC server socket to enable the VeNCrypt auth 2394 mechanism. The credentials should have been previously created 2395 using the ``-object tls-creds`` argument. 2396 2397 ``tls-authz=ID`` 2398 Provides the ID of the QAuthZ authorization object against which 2399 the client's x509 distinguished name will validated. This object 2400 is only resolved at time of use, so can be deleted and recreated 2401 on the fly while the VNC server is active. If missing, it will 2402 default to denying access. 2403 2404 ``sasl=on|off`` 2405 Require that the client use SASL to authenticate with the VNC 2406 server. The exact choice of authentication method used is 2407 controlled from the system / user's SASL configuration file for 2408 the 'qemu' service. This is typically found in 2409 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, 2410 an environment variable SASL\_CONF\_PATH can be used to make it 2411 search alternate locations for the service config. While some 2412 SASL auth methods can also provide data encryption (eg GSSAPI), 2413 it is recommended that SASL always be combined with the 'tls' 2414 and 'x509' settings to enable use of SSL and server 2415 certificates. This ensures a data encryption preventing 2416 compromise of authentication credentials. See the 2417 :ref:`VNC security` section in the System Emulation Users Guide 2418 for details on using SASL authentication. 2419 2420 ``sasl-authz=ID`` 2421 Provides the ID of the QAuthZ authorization object against which 2422 the client's SASL username will validated. This object is only 2423 resolved at time of use, so can be deleted and recreated on the 2424 fly while the VNC server is active. If missing, it will default 2425 to denying access. 2426 2427 ``acl=on|off`` 2428 Legacy method for enabling authorization of clients against the 2429 x509 distinguished name and SASL username. It results in the 2430 creation of two ``authz-list`` objects with IDs of 2431 ``vnc.username`` and ``vnc.x509dname``. The rules for these 2432 objects must be configured with the HMP ACL commands. 2433 2434 This option is deprecated and should no longer be used. The new 2435 ``sasl-authz`` and ``tls-authz`` options are a replacement. 2436 2437 ``lossy=on|off`` 2438 Enable lossy compression methods (gradient, JPEG, ...). If this 2439 option is set, VNC client may receive lossy framebuffer updates 2440 depending on its encoding settings. Enabling this option can 2441 save a lot of bandwidth at the expense of quality. 2442 2443 ``non-adaptive=on|off`` 2444 Disable adaptive encodings. Adaptive encodings are enabled by 2445 default. An adaptive encoding will try to detect frequently 2446 updated screen regions, and send updates in these regions using 2447 a lossy encoding (like JPEG). This can be really helpful to save 2448 bandwidth when playing videos. Disabling adaptive encodings 2449 restores the original static behavior of encodings like Tight. 2450 2451 ``share=[allow-exclusive|force-shared|ignore]`` 2452 Set display sharing policy. 'allow-exclusive' allows clients to 2453 ask for exclusive access. As suggested by the rfb spec this is 2454 implemented by dropping other connections. Connecting multiple 2455 clients in parallel requires all clients asking for a shared 2456 session (vncviewer: -shared switch). This is the default. 2457 'force-shared' disables exclusive client access. Useful for 2458 shared desktop sessions, where you don't want someone forgetting 2459 specify -shared disconnect everybody else. 'ignore' completely 2460 ignores the shared flag and allows everybody connect 2461 unconditionally. Doesn't conform to the rfb spec but is 2462 traditional QEMU behavior. 2463 2464 ``key-delay-ms`` 2465 Set keyboard delay, for key down and key up events, in 2466 milliseconds. Default is 10. Keyboards are low-bandwidth 2467 devices, so this slowdown can help the device and guest to keep 2468 up and not lose events in case events are arriving in bulk. 2469 Possible causes for the latter are flaky network connections, or 2470 scripts for automated testing. 2471 2472 ``audiodev=audiodev`` 2473 Use the specified audiodev when the VNC client requests audio 2474 transmission. When not using an -audiodev argument, this option 2475 must be omitted, otherwise is must be present and specify a 2476 valid audiodev. 2477 2478 ``power-control=on|off`` 2479 Permit the remote client to issue shutdown, reboot or reset power 2480 control requests. 2481ERST 2482 2483ARCHHEADING(, QEMU_ARCH_I386) 2484 2485ARCHHEADING(i386 target only:, QEMU_ARCH_I386) 2486 2487DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack, 2488 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n", 2489 QEMU_ARCH_I386) 2490SRST 2491``-win2k-hack`` 2492 Use it when installing Windows 2000 to avoid a disk full bug. After 2493 Windows 2000 is installed, you no longer need this option (this 2494 option slows down the IDE transfers). 2495ERST 2496 2497DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk, 2498 "-no-fd-bootchk disable boot signature checking for floppy disks\n", 2499 QEMU_ARCH_I386) 2500SRST 2501``-no-fd-bootchk`` 2502 Disable boot signature checking for floppy disks in BIOS. May be 2503 needed to boot from old floppy disks. 2504ERST 2505 2506DEF("no-acpi", 0, QEMU_OPTION_no_acpi, 2507 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2508SRST 2509``-no-acpi`` 2510 Disable ACPI (Advanced Configuration and Power Interface) support. 2511 Use it if your guest OS complains about ACPI problems (PC target 2512 machine only). 2513ERST 2514 2515DEF("no-hpet", 0, QEMU_OPTION_no_hpet, 2516 "-no-hpet disable HPET\n", QEMU_ARCH_I386) 2517SRST 2518``-no-hpet`` 2519 Disable HPET support. 2520ERST 2521 2522DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable, 2523 "-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" 2524 " ACPI table description\n", QEMU_ARCH_I386) 2525SRST 2526``-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]...]`` 2527 Add ACPI table with specified header fields and context from 2528 specified files. For file=, take whole ACPI table from the specified 2529 files, including all ACPI headers (possible overridden by other 2530 options). For data=, only data portion of the table is used, all 2531 header information is specified in the command line. If a SLIC table 2532 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id 2533 fields will override the same in the RSDT and the FADT (a.k.a. 2534 FACP), in order to ensure the field matches required by the 2535 Microsoft SLIC spec and the ACPI spec. 2536ERST 2537 2538DEF("smbios", HAS_ARG, QEMU_OPTION_smbios, 2539 "-smbios file=binary\n" 2540 " load SMBIOS entry from binary file\n" 2541 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n" 2542 " [,uefi=on|off]\n" 2543 " specify SMBIOS type 0 fields\n" 2544 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2545 " [,uuid=uuid][,sku=str][,family=str]\n" 2546 " specify SMBIOS type 1 fields\n" 2547 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2548 " [,asset=str][,location=str]\n" 2549 " specify SMBIOS type 2 fields\n" 2550 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n" 2551 " [,sku=str]\n" 2552 " specify SMBIOS type 3 fields\n" 2553 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n" 2554 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n" 2555 " [,processor-id=%d]\n" 2556 " specify SMBIOS type 4 fields\n" 2557 "-smbios type=11[,value=str][,path=filename]\n" 2558 " specify SMBIOS type 11 fields\n" 2559 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n" 2560 " [,asset=str][,part=str][,speed=%d]\n" 2561 " specify SMBIOS type 17 fields\n" 2562 "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n" 2563 " specify SMBIOS type 41 fields\n", 2564 QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2565SRST 2566``-smbios file=binary`` 2567 Load SMBIOS entry from binary file. 2568 2569``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]`` 2570 Specify SMBIOS type 0 fields 2571 2572``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]`` 2573 Specify SMBIOS type 1 fields 2574 2575``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]`` 2576 Specify SMBIOS type 2 fields 2577 2578``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]`` 2579 Specify SMBIOS type 3 fields 2580 2581``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str][,processor-id=%d]`` 2582 Specify SMBIOS type 4 fields 2583 2584``-smbios type=11[,value=str][,path=filename]`` 2585 Specify SMBIOS type 11 fields 2586 2587 This argument can be repeated multiple times, and values are added in the order they are parsed. 2588 Applications intending to use OEM strings data are encouraged to use their application name as 2589 a prefix for the value string. This facilitates passing information for multiple applications 2590 concurrently. 2591 2592 The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax 2593 loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes. 2594 2595 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to 2596 the SMBIOS table in the order in which they appear. 2597 2598 Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535 2599 bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the 2600 guest. Instead it should be used as a indicator to inform the guest where to locate the real 2601 data set, for example, by specifying the serial ID of a block device. 2602 2603 An example passing three strings is 2604 2605 .. parsed-literal:: 2606 2607 -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\ 2608 value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\ 2609 path=/some/file/with/oemstringsdata.txt 2610 2611 In the guest OS this is visible with the ``dmidecode`` command 2612 2613 .. parsed-literal:: 2614 2615 $ dmidecode -t 11 2616 Handle 0x0E00, DMI type 11, 5 bytes 2617 OEM Strings 2618 String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/ 2619 String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os 2620 String 3: myapp:some extra data 2621 2622 2623``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]`` 2624 Specify SMBIOS type 17 fields 2625 2626``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]`` 2627 Specify SMBIOS type 41 fields 2628 2629 This argument can be repeated multiple times. Its main use is to allow network interfaces be created 2630 as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface 2631 position on the PCI bus. 2632 2633 Here is an example of use: 2634 2635 .. parsed-literal:: 2636 2637 -netdev user,id=internet \\ 2638 -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\ 2639 -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev 2640 2641 In the guest OS, the device should then appear as ``eno1``: 2642 2643 ..parsed-literal:: 2644 2645 $ ip -brief l 2646 lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP> 2647 eno1 UP 50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP> 2648 2649 Currently, the PCI device has to be attached to the root bus. 2650 2651ERST 2652 2653DEFHEADING() 2654 2655DEFHEADING(Network options:) 2656 2657DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, 2658#ifdef CONFIG_SLIRP 2659 "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n" 2660 " [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n" 2661 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n" 2662 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n" 2663 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]" 2664#ifndef _WIN32 2665 "[,smb=dir[,smbserver=addr]]\n" 2666#endif 2667 " configure a user mode network backend with ID 'str',\n" 2668 " its DHCP server and optional services\n" 2669#endif 2670#ifdef _WIN32 2671 "-netdev tap,id=str,ifname=name\n" 2672 " configure a host TAP network backend with ID 'str'\n" 2673#else 2674 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n" 2675 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" 2676 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" 2677 " [,poll-us=n]\n" 2678 " configure a host TAP network backend with ID 'str'\n" 2679 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2680 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n" 2681 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n" 2682 " to deconfigure it\n" 2683 " use '[down]script=no' to disable script execution\n" 2684 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n" 2685 " configure it\n" 2686 " use 'fd=h' to connect to an already opened TAP interface\n" 2687 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n" 2688 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n" 2689 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n" 2690 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" 2691 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" 2692 " use vhost=on to enable experimental in kernel accelerator\n" 2693 " (only has effect for virtio guests which use MSIX)\n" 2694 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" 2695 " use 'vhostfd=h' to connect to an already opened vhost net device\n" 2696 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n" 2697 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n" 2698 " use 'poll-us=n' to specify the maximum number of microseconds that could be\n" 2699 " spent on busy polling for vhost net\n" 2700 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n" 2701 " configure a host TAP network backend with ID 'str' that is\n" 2702 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2703 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n" 2704#endif 2705#ifdef __linux__ 2706 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n" 2707 " [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n" 2708 " [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n" 2709 " [,rxcookie=rxcookie][,offset=offset]\n" 2710 " configure a network backend with ID 'str' connected to\n" 2711 " an Ethernet over L2TPv3 pseudowire.\n" 2712 " Linux kernel 3.3+ as well as most routers can talk\n" 2713 " L2TPv3. This transport allows connecting a VM to a VM,\n" 2714 " VM to a router and even VM to Host. It is a nearly-universal\n" 2715 " standard (RFC3931). Note - this implementation uses static\n" 2716 " pre-configured tunnels (same as the Linux kernel).\n" 2717 " use 'src=' to specify source address\n" 2718 " use 'dst=' to specify destination address\n" 2719 " use 'udp=on' to specify udp encapsulation\n" 2720 " use 'srcport=' to specify source udp port\n" 2721 " use 'dstport=' to specify destination udp port\n" 2722 " use 'ipv6=on' to force v6\n" 2723 " L2TPv3 uses cookies to prevent misconfiguration as\n" 2724 " well as a weak security measure\n" 2725 " use 'rxcookie=0x012345678' to specify a rxcookie\n" 2726 " use 'txcookie=0x012345678' to specify a txcookie\n" 2727 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n" 2728 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n" 2729 " use 'pincounter=on' to work around broken counter handling in peer\n" 2730 " use 'offset=X' to add an extra offset between header and data\n" 2731#endif 2732 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n" 2733 " configure a network backend to connect to another network\n" 2734 " using a socket connection\n" 2735 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n" 2736 " configure a network backend to connect to a multicast maddr and port\n" 2737 " use 'localaddr=addr' to specify the host address to send packets from\n" 2738 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n" 2739 " configure a network backend to connect to another network\n" 2740 " using an UDP tunnel\n" 2741#ifdef CONFIG_VDE 2742 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n" 2743 " configure a network backend to connect to port 'n' of a vde switch\n" 2744 " running on host and listening for incoming connections on 'socketpath'.\n" 2745 " Use group 'groupname' and mode 'octalmode' to change default\n" 2746 " ownership and permissions for communication port.\n" 2747#endif 2748#ifdef CONFIG_NETMAP 2749 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n" 2750 " attach to the existing netmap-enabled network interface 'name', or to a\n" 2751 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n" 2752 " netmap device, defaults to '/dev/netmap')\n" 2753#endif 2754#ifdef CONFIG_POSIX 2755 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" 2756 " configure a vhost-user network, backed by a chardev 'dev'\n" 2757#endif 2758#ifdef __linux__ 2759 "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n" 2760 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n" 2761#endif 2762 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n" 2763 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL) 2764DEF("nic", HAS_ARG, QEMU_OPTION_nic, 2765 "-nic [tap|bridge|" 2766#ifdef CONFIG_SLIRP 2767 "user|" 2768#endif 2769#ifdef __linux__ 2770 "l2tpv3|" 2771#endif 2772#ifdef CONFIG_VDE 2773 "vde|" 2774#endif 2775#ifdef CONFIG_NETMAP 2776 "netmap|" 2777#endif 2778#ifdef CONFIG_POSIX 2779 "vhost-user|" 2780#endif 2781 "socket][,option][,...][mac=macaddr]\n" 2782 " initialize an on-board / default host NIC (using MAC address\n" 2783 " macaddr) and connect it to the given host network backend\n" 2784 "-nic none use it alone to have zero network devices (the default is to\n" 2785 " provided a 'user' network connection)\n", 2786 QEMU_ARCH_ALL) 2787DEF("net", HAS_ARG, QEMU_OPTION_net, 2788 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" 2789 " configure or create an on-board (or machine default) NIC and\n" 2790 " connect it to hub 0 (please use -nic unless you need a hub)\n" 2791 "-net [" 2792#ifdef CONFIG_SLIRP 2793 "user|" 2794#endif 2795 "tap|" 2796 "bridge|" 2797#ifdef CONFIG_VDE 2798 "vde|" 2799#endif 2800#ifdef CONFIG_NETMAP 2801 "netmap|" 2802#endif 2803 "socket][,option][,option][,...]\n" 2804 " old way to initialize a host network interface\n" 2805 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL) 2806SRST 2807``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]`` 2808 This option is a shortcut for configuring both the on-board 2809 (default) guest NIC hardware and the host network backend in one go. 2810 The host backend options are the same as with the corresponding 2811 ``-netdev`` options below. The guest NIC model can be set with 2812 ``model=modelname``. Use ``model=help`` to list the available device 2813 types. The hardware MAC address can be set with ``mac=macaddr``. 2814 2815 The following two example do exactly the same, to show how ``-nic`` 2816 can be used to shorten the command line length: 2817 2818 .. parsed-literal:: 2819 2820 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32 2821 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32 2822 2823``-nic none`` 2824 Indicate that no network devices should be configured. It is used to 2825 override the default configuration (default NIC with "user" host 2826 network backend) which is activated if no other networking options 2827 are provided. 2828 2829``-netdev user,id=id[,option][,option][,...]`` 2830 Configure user mode host network backend which requires no 2831 administrator privilege to run. Valid options are: 2832 2833 ``id=id`` 2834 Assign symbolic name for use in monitor commands. 2835 2836 ``ipv4=on|off and ipv6=on|off`` 2837 Specify that either IPv4 or IPv6 must be enabled. If neither is 2838 specified both protocols are enabled. 2839 2840 ``net=addr[/mask]`` 2841 Set IP network address the guest will see. Optionally specify 2842 the netmask, either in the form a.b.c.d or as number of valid 2843 top-most bits. Default is 10.0.2.0/24. 2844 2845 ``host=addr`` 2846 Specify the guest-visible address of the host. Default is the 2847 2nd IP in the guest network, i.e. x.x.x.2. 2848 2849 ``ipv6-net=addr[/int]`` 2850 Set IPv6 network address the guest will see (default is 2851 fec0::/64). The network prefix is given in the usual hexadecimal 2852 IPv6 address notation. The prefix size is optional, and is given 2853 as the number of valid top-most bits (default is 64). 2854 2855 ``ipv6-host=addr`` 2856 Specify the guest-visible IPv6 address of the host. Default is 2857 the 2nd IPv6 in the guest network, i.e. xxxx::2. 2858 2859 ``restrict=on|off`` 2860 If this option is enabled, the guest will be isolated, i.e. it 2861 will not be able to contact the host and no guest IP packets 2862 will be routed over the host to the outside. This option does 2863 not affect any explicitly set forwarding rules. 2864 2865 ``hostname=name`` 2866 Specifies the client hostname reported by the built-in DHCP 2867 server. 2868 2869 ``dhcpstart=addr`` 2870 Specify the first of the 16 IPs the built-in DHCP server can 2871 assign. Default is the 15th to 31st IP in the guest network, 2872 i.e. x.x.x.15 to x.x.x.31. 2873 2874 ``dns=addr`` 2875 Specify the guest-visible address of the virtual nameserver. The 2876 address must be different from the host address. Default is the 2877 3rd IP in the guest network, i.e. x.x.x.3. 2878 2879 ``ipv6-dns=addr`` 2880 Specify the guest-visible address of the IPv6 virtual 2881 nameserver. The address must be different from the host address. 2882 Default is the 3rd IP in the guest network, i.e. xxxx::3. 2883 2884 ``dnssearch=domain`` 2885 Provides an entry for the domain-search list sent by the 2886 built-in DHCP server. More than one domain suffix can be 2887 transmitted by specifying this option multiple times. If 2888 supported, this will cause the guest to automatically try to 2889 append the given domain suffix(es) in case a domain name can not 2890 be resolved. 2891 2892 Example: 2893 2894 .. parsed-literal:: 2895 2896 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org 2897 2898 ``domainname=domain`` 2899 Specifies the client domain name reported by the built-in DHCP 2900 server. 2901 2902 ``tftp=dir`` 2903 When using the user mode network stack, activate a built-in TFTP 2904 server. The files in dir will be exposed as the root of a TFTP 2905 server. The TFTP client on the guest must be configured in 2906 binary mode (use the command ``bin`` of the Unix TFTP client). 2907 2908 ``tftp-server-name=name`` 2909 In BOOTP reply, broadcast name as the "TFTP server name" 2910 (RFC2132 option 66). This can be used to advise the guest to 2911 load boot files or configurations from a different server than 2912 the host address. 2913 2914 ``bootfile=file`` 2915 When using the user mode network stack, broadcast file as the 2916 BOOTP filename. In conjunction with ``tftp``, this can be used 2917 to network boot a guest from a local directory. 2918 2919 Example (using pxelinux): 2920 2921 .. parsed-literal:: 2922 2923 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\ 2924 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0 2925 2926 ``smb=dir[,smbserver=addr]`` 2927 When using the user mode network stack, activate a built-in SMB 2928 server so that Windows OSes can access to the host files in 2929 ``dir`` transparently. The IP address of the SMB server can be 2930 set to addr. By default the 4th IP in the guest network is used, 2931 i.e. x.x.x.4. 2932 2933 In the guest Windows OS, the line: 2934 2935 :: 2936 2937 10.0.2.4 smbserver 2938 2939 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows 2940 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows 2941 NT/2000). 2942 2943 Then ``dir`` can be accessed in ``\\smbserver\qemu``. 2944 2945 Note that a SAMBA server must be installed on the host OS. 2946 2947 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport`` 2948 Redirect incoming TCP or UDP connections to the host port 2949 hostport to the guest IP address guestaddr on guest port 2950 guestport. If guestaddr is not specified, its value is x.x.x.15 2951 (default first address given by the built-in DHCP server). By 2952 specifying hostaddr, the rule can be bound to a specific host 2953 interface. If no connection type is set, TCP is used. This 2954 option can be given multiple times. 2955 2956 For example, to redirect host X11 connection from screen 1 to 2957 guest screen 0, use the following: 2958 2959 .. parsed-literal:: 2960 2961 # on the host 2962 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000 2963 # this host xterm should open in the guest X11 server 2964 xterm -display :1 2965 2966 To redirect telnet connections from host port 5555 to telnet 2967 port on the guest, use the following: 2968 2969 .. parsed-literal:: 2970 2971 # on the host 2972 |qemu_system| -nic user,hostfwd=tcp::5555-:23 2973 telnet localhost 5555 2974 2975 Then when you use on the host ``telnet localhost 5555``, you 2976 connect to the guest telnet server. 2977 2978 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command`` 2979 Forward guest TCP connections to the IP address server on port 2980 port to the character device dev or to a program executed by 2981 cmd:command which gets spawned for each connection. This option 2982 can be given multiple times. 2983 2984 You can either use a chardev directly and have that one used 2985 throughout QEMU's lifetime, like in the following example: 2986 2987 .. parsed-literal:: 2988 2989 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever 2990 # the guest accesses it 2991 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 2992 2993 Or you can execute a command on every TCP connection established 2994 by the guest, so that QEMU behaves similar to an inetd process 2995 for that virtual server: 2996 2997 .. parsed-literal:: 2998 2999 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234 3000 # and connect the TCP stream to its stdin/stdout 3001 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321' 3002 3003``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]`` 3004 Configure a host TAP network backend with ID id. 3005 3006 Use the network script file to configure it and the network script 3007 dfile to deconfigure it. If name is not provided, the OS 3008 automatically provides one. The default network configure script is 3009 ``/etc/qemu-ifup`` and the default network deconfigure script is 3010 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to 3011 disable script execution. 3012 3013 If running QEMU as an unprivileged user, use the network helper 3014 to configure the TAP interface and attach it to the bridge. 3015 The default network helper executable is 3016 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3017 ``br0``. 3018 3019 ``fd``\ =h can be used to specify the handle of an already opened 3020 host TAP interface. 3021 3022 Examples: 3023 3024 .. parsed-literal:: 3025 3026 #launch a QEMU instance with the default network script 3027 |qemu_system| linux.img -nic tap 3028 3029 .. parsed-literal:: 3030 3031 #launch a QEMU instance with two NICs, each one connected 3032 #to a TAP device 3033 |qemu_system| linux.img \\ 3034 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\ 3035 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1 3036 3037 .. parsed-literal:: 3038 3039 #launch a QEMU instance with the default network helper to 3040 #connect a TAP device to bridge br0 3041 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\ 3042 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper" 3043 3044``-netdev bridge,id=id[,br=bridge][,helper=helper]`` 3045 Connect a host TAP network interface to a host bridge device. 3046 3047 Use the network helper helper to configure the TAP interface and 3048 attach it to the bridge. The default network helper executable is 3049 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3050 ``br0``. 3051 3052 Examples: 3053 3054 .. parsed-literal:: 3055 3056 #launch a QEMU instance with the default network helper to 3057 #connect a TAP device to bridge br0 3058 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1 3059 3060 .. parsed-literal:: 3061 3062 #launch a QEMU instance with the default network helper to 3063 #connect a TAP device to bridge qemubr0 3064 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1 3065 3066``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]`` 3067 This host network backend can be used to connect the guest's network 3068 to another QEMU virtual machine using a TCP socket connection. If 3069 ``listen`` is specified, QEMU waits for incoming connections on port 3070 (host is optional). ``connect`` is used to connect to another QEMU 3071 instance using the ``listen`` option. ``fd``\ =h specifies an 3072 already opened TCP socket. 3073 3074 Example: 3075 3076 .. parsed-literal:: 3077 3078 # launch a first QEMU instance 3079 |qemu_system| linux.img \\ 3080 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3081 -netdev socket,id=n1,listen=:1234 3082 # connect the network of this instance to the network of the first instance 3083 |qemu_system| linux.img \\ 3084 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3085 -netdev socket,id=n2,connect=127.0.0.1:1234 3086 3087``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]`` 3088 Configure a socket host network backend to share the guest's network 3089 traffic with another QEMU virtual machines using a UDP multicast 3090 socket, effectively making a bus for every QEMU with same multicast 3091 address maddr and port. NOTES: 3092 3093 1. Several QEMU can be running on different hosts and share same bus 3094 (assuming correct multicast setup for these hosts). 3095 3096 2. mcast support is compatible with User Mode Linux (argument 3097 ``ethN=mcast``), see http://user-mode-linux.sf.net. 3098 3099 3. Use ``fd=h`` to specify an already opened UDP multicast socket. 3100 3101 Example: 3102 3103 .. parsed-literal:: 3104 3105 # launch one QEMU instance 3106 |qemu_system| linux.img \\ 3107 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3108 -netdev socket,id=n1,mcast=230.0.0.1:1234 3109 # launch another QEMU instance on same "bus" 3110 |qemu_system| linux.img \\ 3111 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3112 -netdev socket,id=n2,mcast=230.0.0.1:1234 3113 # launch yet another QEMU instance on same "bus" 3114 |qemu_system| linux.img \\ 3115 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\ 3116 -netdev socket,id=n3,mcast=230.0.0.1:1234 3117 3118 Example (User Mode Linux compat.): 3119 3120 .. parsed-literal:: 3121 3122 # launch QEMU instance (note mcast address selected is UML's default) 3123 |qemu_system| linux.img \\ 3124 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3125 -netdev socket,id=n1,mcast=239.192.168.1:1102 3126 # launch UML 3127 /path/to/linux ubd0=/path/to/root_fs eth0=mcast 3128 3129 Example (send packets from host's 1.2.3.4): 3130 3131 .. parsed-literal:: 3132 3133 |qemu_system| linux.img \\ 3134 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3135 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4 3136 3137``-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]`` 3138 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931) 3139 is a popular protocol to transport Ethernet (and other Layer 2) data 3140 frames between two systems. It is present in routers, firewalls and 3141 the Linux kernel (from version 3.3 onwards). 3142 3143 This transport allows a VM to communicate to another VM, router or 3144 firewall directly. 3145 3146 ``src=srcaddr`` 3147 source address (mandatory) 3148 3149 ``dst=dstaddr`` 3150 destination address (mandatory) 3151 3152 ``udp`` 3153 select udp encapsulation (default is ip). 3154 3155 ``srcport=srcport`` 3156 source udp port. 3157 3158 ``dstport=dstport`` 3159 destination udp port. 3160 3161 ``ipv6`` 3162 force v6, otherwise defaults to v4. 3163 3164 ``rxcookie=rxcookie``; \ ``txcookie=txcookie`` 3165 Cookies are a weak form of security in the l2tpv3 specification. 3166 Their function is mostly to prevent misconfiguration. By default 3167 they are 32 bit. 3168 3169 ``cookie64`` 3170 Set cookie size to 64 bit instead of the default 32 3171 3172 ``counter=off`` 3173 Force a 'cut-down' L2TPv3 with no counter as in 3174 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00 3175 3176 ``pincounter=on`` 3177 Work around broken counter handling in peer. This may also help 3178 on networks which have packet reorder. 3179 3180 ``offset=offset`` 3181 Add an extra offset between header and data 3182 3183 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to 3184 the bridge br-lan on the remote Linux host 1.2.3.4: 3185 3186 .. parsed-literal:: 3187 3188 # Setup tunnel on linux host using raw ip as encapsulation 3189 # on 1.2.3.4 3190 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\ 3191 encap udp udp_sport 16384 udp_dport 16384 3192 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\ 3193 0xFFFFFFFF peer_session_id 0xFFFFFFFF 3194 ifconfig vmtunnel0 mtu 1500 3195 ifconfig vmtunnel0 up 3196 brctl addif br-lan vmtunnel0 3197 3198 3199 # on 4.3.2.1 3200 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter 3201 3202 |qemu_system| linux.img -device e1000,netdev=n1 \\ 3203 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter 3204 3205``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]`` 3206 Configure VDE backend to connect to PORT n of a vde switch running 3207 on host and listening for incoming connections on socketpath. Use 3208 GROUP groupname and MODE octalmode to change default ownership and 3209 permissions for communication port. This option is only available if 3210 QEMU has been compiled with vde support enabled. 3211 3212 Example: 3213 3214 .. parsed-literal:: 3215 3216 # launch vde switch 3217 vde_switch -F -sock /tmp/myswitch 3218 # launch QEMU instance 3219 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch 3220 3221``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]`` 3222 Establish a vhost-user netdev, backed by a chardev id. The chardev 3223 should be a unix domain socket backed one. The vhost-user uses a 3224 specifically defined protocol to pass vhost ioctl replacement 3225 messages to an application on the other end of the socket. On 3226 non-MSIX guests, the feature can be forced with vhostforce. Use 3227 'queues=n' to specify the number of queues to be created for 3228 multiqueue vhost-user. 3229 3230 Example: 3231 3232 :: 3233 3234 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \ 3235 -numa node,memdev=mem \ 3236 -chardev socket,id=chr0,path=/path/to/socket \ 3237 -netdev type=vhost-user,id=net0,chardev=chr0 \ 3238 -device virtio-net-pci,netdev=net0 3239 3240``-netdev vhost-vdpa,vhostdev=/path/to/dev`` 3241 Establish a vhost-vdpa netdev. 3242 3243 vDPA device is a device that uses a datapath which complies with 3244 the virtio specifications with a vendor specific control path. 3245 vDPA devices can be both physically located on the hardware or 3246 emulated by software. 3247 3248``-netdev hubport,id=id,hubid=hubid[,netdev=nd]`` 3249 Create a hub port on the emulated hub with ID hubid. 3250 3251 The hubport netdev lets you connect a NIC to a QEMU emulated hub 3252 instead of a single netdev. Alternatively, you can also connect the 3253 hubport to another netdev with ID nd by using the ``netdev=nd`` 3254 option. 3255 3256``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]`` 3257 Legacy option to configure or create an on-board (or machine 3258 default) Network Interface Card(NIC) and connect it either to the 3259 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd. 3260 If model is omitted, then the default NIC model associated with the 3261 machine type is used. Note that the default NIC model may change in 3262 future QEMU releases, so it is highly recommended to always specify 3263 a model. Optionally, the MAC address can be changed to mac, the 3264 device address set to addr (PCI cards only), and a name can be 3265 assigned for use in monitor commands. Optionally, for PCI cards, you 3266 can specify the number v of MSI-X vectors that the card should have; 3267 this option currently only affects virtio cards; set v = 0 to 3268 disable MSI-X. If no ``-net`` option is specified, a single NIC is 3269 created. QEMU can emulate several different models of network card. 3270 Use ``-net nic,model=help`` for a list of available devices for your 3271 target. 3272 3273``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]`` 3274 Configure a host network backend (with the options corresponding to 3275 the same ``-netdev`` option) and connect it to the emulated hub 0 3276 (the default hub). Use name to specify the name of the hub port. 3277ERST 3278 3279DEFHEADING() 3280 3281DEFHEADING(Character device options:) 3282 3283DEF("chardev", HAS_ARG, QEMU_OPTION_chardev, 3284 "-chardev help\n" 3285 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3286 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n" 3287 " [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n" 3288 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n" 3289 "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n" 3290 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n" 3291 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n" 3292 " [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n" 3293 " [,logfile=PATH][,logappend=on|off]\n" 3294 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3295 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n" 3296 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3297 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n" 3298 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3299 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3300#ifdef _WIN32 3301 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3302 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3303#else 3304 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3305 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n" 3306#endif 3307#ifdef CONFIG_BRLAPI 3308 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3309#endif 3310#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ 3311 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) 3312 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3313 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3314#endif 3315#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__) 3316 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3317 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3318#endif 3319#if defined(CONFIG_SPICE) 3320 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3321 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3322#endif 3323 , QEMU_ARCH_ALL 3324) 3325 3326SRST 3327The general form of a character device option is: 3328 3329``-chardev backend,id=id[,mux=on|off][,options]`` 3330 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, 3331 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``, 3332 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``, 3333 ``spicevmc``, ``spiceport``. The specific backend will determine the 3334 applicable options. 3335 3336 Use ``-chardev help`` to print all available chardev backend types. 3337 3338 All devices must have an id, which can be any string up to 127 3339 characters long. It is used to uniquely identify this device in 3340 other command line directives. 3341 3342 A character device may be used in multiplexing mode by multiple 3343 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is 3344 a "1:N" device, and here the "1" end is your specified chardev 3345 backend, and the "N" end is the various parts of QEMU that can talk 3346 to a chardev. If you create a chardev with ``id=myid`` and 3347 ``mux=on``, QEMU will create a multiplexer with your specified ID, 3348 and you can then configure multiple front ends to use that chardev 3349 ID for their input/output. Up to four different front ends can be 3350 connected to a single multiplexed chardev. (Without multiplexing 3351 enabled, a chardev can only be used by a single front end.) For 3352 instance you could use this to allow a single stdio chardev to be 3353 used by two serial ports and the QEMU monitor: 3354 3355 :: 3356 3357 -chardev stdio,mux=on,id=char0 \ 3358 -mon chardev=char0,mode=readline \ 3359 -serial chardev:char0 \ 3360 -serial chardev:char0 3361 3362 You can have more than one multiplexer in a system configuration; 3363 for instance you could have a TCP port multiplexed between UART 0 3364 and UART 1, and stdio multiplexed between the QEMU monitor and a 3365 parallel port: 3366 3367 :: 3368 3369 -chardev stdio,mux=on,id=char0 \ 3370 -mon chardev=char0,mode=readline \ 3371 -parallel chardev:char0 \ 3372 -chardev tcp,...,mux=on,id=char1 \ 3373 -serial chardev:char1 \ 3374 -serial chardev:char1 3375 3376 When you're using a multiplexed character device, some escape 3377 sequences are interpreted in the input. See the chapter about 3378 :ref:`keys in the character backend multiplexer` in the 3379 System Emulation Users Guide for more details. 3380 3381 Note that some other command line options may implicitly create 3382 multiplexed character backends; for instance ``-serial mon:stdio`` 3383 creates a multiplexed stdio backend connected to the serial port and 3384 the QEMU monitor, and ``-nographic`` also multiplexes the console 3385 and the monitor to stdio. 3386 3387 There is currently no support for multiplexing in the other 3388 direction (where a single QEMU front end takes input and output from 3389 multiple chardevs). 3390 3391 Every backend supports the ``logfile`` option, which supplies the 3392 path to a file to record all data transmitted via the backend. The 3393 ``logappend`` option controls whether the log file will be truncated 3394 or appended to when opened. 3395 3396The available backends are: 3397 3398``-chardev null,id=id`` 3399 A void device. This device will not emit any data, and will drop any 3400 data it receives. The null backend does not take any options. 3401 3402``-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]`` 3403 Create a two-way stream socket, which can be either a TCP or a unix 3404 socket. A unix socket will be created if ``path`` is specified. 3405 Behaviour is undefined if TCP options are specified for a unix 3406 socket. 3407 3408 ``server=on|off`` specifies that the socket shall be a listening socket. 3409 3410 ``wait=on|off`` specifies that QEMU should not block waiting for a client 3411 to connect to a listening socket. 3412 3413 ``telnet=on|off`` specifies that traffic on the socket should interpret 3414 telnet escape sequences. 3415 3416 ``websocket=on|off`` specifies that the socket uses WebSocket protocol for 3417 communication. 3418 3419 ``reconnect`` sets the timeout for reconnecting on non-server 3420 sockets when the remote end goes away. qemu will delay this many 3421 seconds and then attempt to reconnect. Zero disables reconnecting, 3422 and is the default. 3423 3424 ``tls-creds`` requests enablement of the TLS protocol for 3425 encryption, and specifies the id of the TLS credentials to use for 3426 the handshake. The credentials must be previously created with the 3427 ``-object tls-creds`` argument. 3428 3429 ``tls-auth`` provides the ID of the QAuthZ authorization object 3430 against which the client's x509 distinguished name will be 3431 validated. This object is only resolved at time of use, so can be 3432 deleted and recreated on the fly while the chardev server is active. 3433 If missing, it will default to denying access. 3434 3435 TCP and unix socket options are given below: 3436 3437 ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]`` 3438 ``host`` for a listening socket specifies the local address to 3439 be bound. For a connecting socket species the remote host to 3440 connect to. ``host`` is optional for listening sockets. If not 3441 specified it defaults to ``0.0.0.0``. 3442 3443 ``port`` for a listening socket specifies the local port to be 3444 bound. For a connecting socket specifies the port on the remote 3445 host to connect to. ``port`` can be given as either a port 3446 number or a service name. ``port`` is required. 3447 3448 ``to`` is only relevant to listening sockets. If it is 3449 specified, and ``port`` cannot be bound, QEMU will attempt to 3450 bind to subsequent ports up to and including ``to`` until it 3451 succeeds. ``to`` must be specified as a port number. 3452 3453 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 3454 or IPv6 must be used. If neither is specified the socket may 3455 use either protocol. 3456 3457 ``nodelay=on|off`` disables the Nagle algorithm. 3458 3459 ``unix options: path=path[,abstract=on|off][,tight=on|off]`` 3460 ``path`` specifies the local path of the unix socket. ``path`` 3461 is required. 3462 ``abstract=on|off`` specifies the use of the abstract socket namespace, 3463 rather than the filesystem. Optional, defaults to false. 3464 ``tight=on|off`` sets the socket length of abstract sockets to their minimum, 3465 rather than the full sun_path length. Optional, defaults to true. 3466 3467``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]`` 3468 Sends all traffic from the guest to a remote host over UDP. 3469 3470 ``host`` specifies the remote host to connect to. If not specified 3471 it defaults to ``localhost``. 3472 3473 ``port`` specifies the port on the remote host to connect to. 3474 ``port`` is required. 3475 3476 ``localaddr`` specifies the local address to bind to. If not 3477 specified it defaults to ``0.0.0.0``. 3478 3479 ``localport`` specifies the local port to bind to. If not specified 3480 any available local port will be used. 3481 3482 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used. 3483 If neither is specified the device may use either protocol. 3484 3485``-chardev msmouse,id=id`` 3486 Forward QEMU's emulated msmouse events to the guest. ``msmouse`` 3487 does not take any options. 3488 3489``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]`` 3490 Connect to a QEMU text console. ``vc`` may optionally be given a 3491 specific size. 3492 3493 ``width`` and ``height`` specify the width and height respectively 3494 of the console, in pixels. 3495 3496 ``cols`` and ``rows`` specify that the console be sized to fit a 3497 text console with the given dimensions. 3498 3499``-chardev ringbuf,id=id[,size=size]`` 3500 Create a ring buffer with fixed size ``size``. size must be a power 3501 of two and defaults to ``64K``. 3502 3503``-chardev file,id=id,path=path`` 3504 Log all traffic received from the guest to a file. 3505 3506 ``path`` specifies the path of the file to be opened. This file will 3507 be created if it does not already exist, and overwritten if it does. 3508 ``path`` is required. 3509 3510``-chardev pipe,id=id,path=path`` 3511 Create a two-way connection to the guest. The behaviour differs 3512 slightly between Windows hosts and other hosts: 3513 3514 On Windows, a single duplex pipe will be created at 3515 ``\\.pipe\path``. 3516 3517 On other hosts, 2 pipes will be created called ``path.in`` and 3518 ``path.out``. Data written to ``path.in`` will be received by the 3519 guest. Data written by the guest can be read from ``path.out``. QEMU 3520 will not create these fifos, and requires them to be present. 3521 3522 ``path`` forms part of the pipe path as described above. ``path`` is 3523 required. 3524 3525``-chardev console,id=id`` 3526 Send traffic from the guest to QEMU's standard output. ``console`` 3527 does not take any options. 3528 3529 ``console`` is only available on Windows hosts. 3530 3531``-chardev serial,id=id,path=path`` 3532 Send traffic from the guest to a serial device on the host. 3533 3534 On Unix hosts serial will actually accept any tty device, not only 3535 serial lines. 3536 3537 ``path`` specifies the name of the serial device to open. 3538 3539``-chardev pty,id=id`` 3540 Create a new pseudo-terminal on the host and connect to it. ``pty`` 3541 does not take any options. 3542 3543 ``pty`` is not available on Windows hosts. 3544 3545``-chardev stdio,id=id[,signal=on|off]`` 3546 Connect to standard input and standard output of the QEMU process. 3547 3548 ``signal`` controls if signals are enabled on the terminal, that 3549 includes exiting QEMU with the key sequence Control-c. This option 3550 is enabled by default, use ``signal=off`` to disable it. 3551 3552``-chardev braille,id=id`` 3553 Connect to a local BrlAPI server. ``braille`` does not take any 3554 options. 3555 3556``-chardev tty,id=id,path=path`` 3557 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD 3558 and DragonFlyBSD hosts. It is an alias for ``serial``. 3559 3560 ``path`` specifies the path to the tty. ``path`` is required. 3561 3562``-chardev parallel,id=id,path=path`` 3563 \ 3564``-chardev parport,id=id,path=path`` 3565 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD 3566 hosts. 3567 3568 Connect to a local parallel port. 3569 3570 ``path`` specifies the path to the parallel port device. ``path`` is 3571 required. 3572 3573``-chardev spicevmc,id=id,debug=debug,name=name`` 3574 ``spicevmc`` is only available when spice support is built in. 3575 3576 ``debug`` debug level for spicevmc 3577 3578 ``name`` name of spice channel to connect to 3579 3580 Connect to a spice virtual machine channel, such as vdiport. 3581 3582``-chardev spiceport,id=id,debug=debug,name=name`` 3583 ``spiceport`` is only available when spice support is built in. 3584 3585 ``debug`` debug level for spicevmc 3586 3587 ``name`` name of spice port to connect to 3588 3589 Connect to a spice port, allowing a Spice client to handle the 3590 traffic identified by a name (preferably a fqdn). 3591ERST 3592 3593DEFHEADING() 3594 3595#ifdef CONFIG_TPM 3596DEFHEADING(TPM device options:) 3597 3598DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \ 3599 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n" 3600 " use path to provide path to a character device; default is /dev/tpm0\n" 3601 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n" 3602 " not provided it will be searched for in /sys/class/misc/tpm?/device\n" 3603 "-tpmdev emulator,id=id,chardev=dev\n" 3604 " configure the TPM device using chardev backend\n", 3605 QEMU_ARCH_ALL) 3606SRST 3607The general form of a TPM device option is: 3608 3609``-tpmdev backend,id=id[,options]`` 3610 The specific backend type will determine the applicable options. The 3611 ``-tpmdev`` option creates the TPM backend and requires a 3612 ``-device`` option that specifies the TPM frontend interface model. 3613 3614 Use ``-tpmdev help`` to print all available TPM backend types. 3615 3616The available backends are: 3617 3618``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path`` 3619 (Linux-host only) Enable access to the host's TPM using the 3620 passthrough driver. 3621 3622 ``path`` specifies the path to the host's TPM device, i.e., on a 3623 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by 3624 default ``/dev/tpm0`` is used. 3625 3626 ``cancel-path`` specifies the path to the host TPM device's sysfs 3627 entry allowing for cancellation of an ongoing TPM command. 3628 ``cancel-path`` is optional and by default QEMU will search for the 3629 sysfs entry to use. 3630 3631 Some notes about using the host's TPM with the passthrough driver: 3632 3633 The TPM device accessed by the passthrough driver must not be used 3634 by any other application on the host. 3635 3636 Since the host's firmware (BIOS/UEFI) has already initialized the 3637 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize 3638 the TPM again and may therefore not show a TPM-specific menu that 3639 would otherwise allow the user to configure the TPM, e.g., allow the 3640 user to enable/disable or activate/deactivate the TPM. Further, if 3641 TPM ownership is released from within a VM then the host's TPM will 3642 get disabled and deactivated. To enable and activate the TPM again 3643 afterwards, the host has to be rebooted and the user is required to 3644 enter the firmware's menu to enable and activate the TPM. If the TPM 3645 is left disabled and/or deactivated most TPM commands will fail. 3646 3647 To create a passthrough TPM use the following two options: 3648 3649 :: 3650 3651 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0 3652 3653 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by 3654 ``tpmdev=tpm0`` in the device option. 3655 3656``-tpmdev emulator,id=id,chardev=dev`` 3657 (Linux-host only) Enable access to a TPM emulator using Unix domain 3658 socket based chardev backend. 3659 3660 ``chardev`` specifies the unique ID of a character device backend 3661 that provides connection to the software TPM server. 3662 3663 To create a TPM emulator backend device with chardev socket backend: 3664 3665 :: 3666 3667 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0 3668ERST 3669 3670DEFHEADING() 3671 3672#endif 3673 3674DEFHEADING(Linux/Multiboot boot specific:) 3675SRST 3676When using these options, you can use a given Linux or Multiboot kernel 3677without installing it in the disk image. It can be useful for easier 3678testing of various kernels. 3679 3680 3681ERST 3682 3683DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \ 3684 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL) 3685SRST 3686``-kernel bzImage`` 3687 Use bzImage as kernel image. The kernel can be either a Linux kernel 3688 or in multiboot format. 3689ERST 3690 3691DEF("append", HAS_ARG, QEMU_OPTION_append, \ 3692 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL) 3693SRST 3694``-append cmdline`` 3695 Use cmdline as kernel command line 3696ERST 3697 3698DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \ 3699 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL) 3700SRST 3701``-initrd file`` 3702 Use file as initial ram disk. 3703 3704``-initrd "file1 arg=foo,file2"`` 3705 This syntax is only available with multiboot. 3706 3707 Use file1 and file2 as modules and pass arg=foo as parameter to the 3708 first module. 3709ERST 3710 3711DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \ 3712 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL) 3713SRST 3714``-dtb file`` 3715 Use file as a device tree binary (dtb) image and pass it to the 3716 kernel on boot. 3717ERST 3718 3719DEFHEADING() 3720 3721DEFHEADING(Debug/Expert options:) 3722 3723DEF("compat", HAS_ARG, QEMU_OPTION_compat, 3724 "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n" 3725 " Policy for handling deprecated management interfaces\n" 3726 "-compat [unstable-input=accept|reject|crash][,unstable-output=accept|hide]\n" 3727 " Policy for handling unstable management interfaces\n", 3728 QEMU_ARCH_ALL) 3729SRST 3730``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]`` 3731 Set policy for handling deprecated management interfaces (experimental): 3732 3733 ``deprecated-input=accept`` (default) 3734 Accept deprecated commands and arguments 3735 ``deprecated-input=reject`` 3736 Reject deprecated commands and arguments 3737 ``deprecated-input=crash`` 3738 Crash on deprecated commands and arguments 3739 ``deprecated-output=accept`` (default) 3740 Emit deprecated command results and events 3741 ``deprecated-output=hide`` 3742 Suppress deprecated command results and events 3743 3744 Limitation: covers only syntactic aspects of QMP. 3745 3746``-compat [unstable-input=@var{input-policy}][,unstable-output=@var{output-policy}]`` 3747 Set policy for handling unstable management interfaces (experimental): 3748 3749 ``unstable-input=accept`` (default) 3750 Accept unstable commands and arguments 3751 ``unstable-input=reject`` 3752 Reject unstable commands and arguments 3753 ``unstable-input=crash`` 3754 Crash on unstable commands and arguments 3755 ``unstable-output=accept`` (default) 3756 Emit unstable command results and events 3757 ``unstable-output=hide`` 3758 Suppress unstable command results and events 3759 3760 Limitation: covers only syntactic aspects of QMP. 3761ERST 3762 3763DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg, 3764 "-fw_cfg [name=]<name>,file=<file>\n" 3765 " add named fw_cfg entry with contents from file\n" 3766 "-fw_cfg [name=]<name>,string=<str>\n" 3767 " add named fw_cfg entry with contents from string\n", 3768 QEMU_ARCH_ALL) 3769SRST 3770``-fw_cfg [name=]name,file=file`` 3771 Add named fw\_cfg entry with contents from file file. 3772 3773``-fw_cfg [name=]name,string=str`` 3774 Add named fw\_cfg entry with contents from string str. 3775 3776 The terminating NUL character of the contents of str will not be 3777 included as part of the fw\_cfg item data. To insert contents with 3778 embedded NUL characters, you have to use the file parameter. 3779 3780 The fw\_cfg entries are passed by QEMU through to the guest. 3781 3782 Example: 3783 3784 :: 3785 3786 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin 3787 3788 creates an fw\_cfg entry named opt/com.mycompany/blob with contents 3789 from ./my\_blob.bin. 3790ERST 3791 3792DEF("serial", HAS_ARG, QEMU_OPTION_serial, \ 3793 "-serial dev redirect the serial port to char device 'dev'\n", 3794 QEMU_ARCH_ALL) 3795SRST 3796``-serial dev`` 3797 Redirect the virtual serial port to host character device dev. The 3798 default device is ``vc`` in graphical mode and ``stdio`` in non 3799 graphical mode. 3800 3801 This option can be used several times to simulate up to 4 serial 3802 ports. 3803 3804 Use ``-serial none`` to disable all serial ports. 3805 3806 Available character devices are: 3807 3808 ``vc[:WxH]`` 3809 Virtual console. Optionally, a width and height can be given in 3810 pixel with 3811 3812 :: 3813 3814 vc:800x600 3815 3816 It is also possible to specify width or height in characters: 3817 3818 :: 3819 3820 vc:80Cx24C 3821 3822 ``pty`` 3823 [Linux only] Pseudo TTY (a new PTY is automatically allocated) 3824 3825 ``none`` 3826 No device is allocated. 3827 3828 ``null`` 3829 void device 3830 3831 ``chardev:id`` 3832 Use a named character device defined with the ``-chardev`` 3833 option. 3834 3835 ``/dev/XXX`` 3836 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial 3837 port parameters are set according to the emulated ones. 3838 3839 ``/dev/parportN`` 3840 [Linux only, parallel port only] Use host parallel port N. 3841 Currently SPP and EPP parallel port features can be used. 3842 3843 ``file:filename`` 3844 Write output to filename. No character can be read. 3845 3846 ``stdio`` 3847 [Unix only] standard input/output 3848 3849 ``pipe:filename`` 3850 name pipe filename 3851 3852 ``COMn`` 3853 [Windows only] Use host serial port n 3854 3855 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]`` 3856 This implements UDP Net Console. When remote\_host or src\_ip 3857 are not specified they default to ``0.0.0.0``. When not using a 3858 specified src\_port a random port is automatically chosen. 3859 3860 If you just want a simple readonly console you can use 3861 ``netcat`` or ``nc``, by starting QEMU with: 3862 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time 3863 QEMU writes something to that port it will appear in the 3864 netconsole session. 3865 3866 If you plan to send characters back via netconsole or you want 3867 to stop and start QEMU a lot of times, you should have QEMU use 3868 the same source port each time by using something like ``-serial 3869 udp::4555@:4556`` to QEMU. Another approach is to use a patched 3870 version of netcat which can listen to a TCP port and send and 3871 receive characters via udp. If you have a patched version of 3872 netcat which activates telnet remote echo and single char 3873 transfer, then you can use the following options to set up a 3874 netcat redirector to allow telnet on port 5555 to access the 3875 QEMU port. 3876 3877 ``QEMU Options:`` 3878 -serial udp::4555@:4556 3879 3880 ``netcat options:`` 3881 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T 3882 3883 ``telnet options:`` 3884 localhost 5555 3885 3886 ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]`` 3887 The TCP Net Console has two modes of operation. It can send the 3888 serial I/O to a location or wait for a connection from a 3889 location. By default the TCP Net Console is sent to host at the 3890 port. If you use the ``server=on`` option QEMU will wait for a client 3891 socket application to connect to the port before continuing, 3892 unless the ``wait=on|off`` option was specified. The ``nodelay=on|off`` 3893 option disables the Nagle buffering algorithm. The ``reconnect=on`` 3894 option only applies if ``server=no`` is set, if the connection goes 3895 down it will attempt to reconnect at the given interval. If host 3896 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a 3897 time is accepted. You can use ``telnet=on`` to connect to the 3898 corresponding character device. 3899 3900 ``Example to send tcp console to 192.168.0.2 port 4444`` 3901 -serial tcp:192.168.0.2:4444 3902 3903 ``Example to listen and wait on port 4444 for connection`` 3904 -serial tcp::4444,server=on 3905 3906 ``Example to not wait and listen on ip 192.168.0.100 port 4444`` 3907 -serial tcp:192.168.0.100:4444,server=on,wait=off 3908 3909 ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]`` 3910 The telnet protocol is used instead of raw tcp sockets. The 3911 options work the same as if you had specified ``-serial tcp``. 3912 The difference is that the port acts like a telnet server or 3913 client using telnet option negotiation. This will also allow you 3914 to send the MAGIC\_SYSRQ sequence if you use a telnet that 3915 supports sending the break sequence. Typically in unix telnet 3916 you do it with Control-] and then type "send break" followed by 3917 pressing the enter key. 3918 3919 ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]`` 3920 The WebSocket protocol is used instead of raw tcp socket. The 3921 port acts as a WebSocket server. Client mode is not supported. 3922 3923 ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]`` 3924 A unix domain socket is used instead of a tcp socket. The option 3925 works the same as if you had specified ``-serial tcp`` except 3926 the unix domain socket path is used for connections. 3927 3928 ``mon:dev_string`` 3929 This is a special option to allow the monitor to be multiplexed 3930 onto another serial port. The monitor is accessed with key 3931 sequence of Control-a and then pressing c. dev\_string should be 3932 any one of the serial devices specified above. An example to 3933 multiplex the monitor onto a telnet server listening on port 3934 4444 would be: 3935 3936 ``-serial mon:telnet::4444,server=on,wait=off`` 3937 3938 When the monitor is multiplexed to stdio in this way, Ctrl+C 3939 will not terminate QEMU any more but will be passed to the guest 3940 instead. 3941 3942 ``braille`` 3943 Braille device. This will use BrlAPI to display the braille 3944 output on a real or fake device. 3945 3946 ``msmouse`` 3947 Three button serial mouse. Configure the guest to use Microsoft 3948 protocol. 3949ERST 3950 3951DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \ 3952 "-parallel dev redirect the parallel port to char device 'dev'\n", 3953 QEMU_ARCH_ALL) 3954SRST 3955``-parallel dev`` 3956 Redirect the virtual parallel port to host device dev (same devices 3957 as the serial port). On Linux hosts, ``/dev/parportN`` can be used 3958 to use hardware devices connected on the corresponding host parallel 3959 port. 3960 3961 This option can be used several times to simulate up to 3 parallel 3962 ports. 3963 3964 Use ``-parallel none`` to disable all parallel ports. 3965ERST 3966 3967DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \ 3968 "-monitor dev redirect the monitor to char device 'dev'\n", 3969 QEMU_ARCH_ALL) 3970SRST 3971``-monitor dev`` 3972 Redirect the monitor to host device dev (same devices as the serial 3973 port). The default device is ``vc`` in graphical mode and ``stdio`` 3974 in non graphical mode. Use ``-monitor none`` to disable the default 3975 monitor. 3976ERST 3977DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \ 3978 "-qmp dev like -monitor but opens in 'control' mode\n", 3979 QEMU_ARCH_ALL) 3980SRST 3981``-qmp dev`` 3982 Like -monitor but opens in 'control' mode. 3983ERST 3984DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \ 3985 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n", 3986 QEMU_ARCH_ALL) 3987SRST 3988``-qmp-pretty dev`` 3989 Like -qmp but uses pretty JSON formatting. 3990ERST 3991 3992DEF("mon", HAS_ARG, QEMU_OPTION_mon, \ 3993 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL) 3994SRST 3995``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]`` 3996 Setup monitor on chardev name. ``mode=control`` configures 3997 a QMP monitor (a JSON RPC-style protocol) and it is not the 3998 same as HMP, the human monitor that has a "(qemu)" prompt. 3999 ``pretty`` is only valid when ``mode=control``, 4000 turning on JSON pretty printing to ease 4001 human reading and debugging. 4002ERST 4003 4004DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \ 4005 "-debugcon dev redirect the debug console to char device 'dev'\n", 4006 QEMU_ARCH_ALL) 4007SRST 4008``-debugcon dev`` 4009 Redirect the debug console to host device dev (same devices as the 4010 serial port). The debug console is an I/O port which is typically 4011 port 0xe9; writing to that I/O port sends output to this device. The 4012 default device is ``vc`` in graphical mode and ``stdio`` in non 4013 graphical mode. 4014ERST 4015 4016DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \ 4017 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL) 4018SRST 4019``-pidfile file`` 4020 Store the QEMU process PID in file. It is useful if you launch QEMU 4021 from a script. 4022ERST 4023 4024DEF("singlestep", 0, QEMU_OPTION_singlestep, \ 4025 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL) 4026SRST 4027``-singlestep`` 4028 Run the emulation in single step mode. 4029ERST 4030 4031DEF("preconfig", 0, QEMU_OPTION_preconfig, \ 4032 "--preconfig pause QEMU before machine is initialized (experimental)\n", 4033 QEMU_ARCH_ALL) 4034SRST 4035``--preconfig`` 4036 Pause QEMU for interactive configuration before the machine is 4037 created, which allows querying and configuring properties that will 4038 affect machine initialization. Use QMP command 'x-exit-preconfig' to 4039 exit the preconfig state and move to the next state (i.e. run guest 4040 if -S isn't used or pause the second time if -S is used). This 4041 option is experimental. 4042ERST 4043 4044DEF("S", 0, QEMU_OPTION_S, \ 4045 "-S freeze CPU at startup (use 'c' to start execution)\n", 4046 QEMU_ARCH_ALL) 4047SRST 4048``-S`` 4049 Do not start CPU at startup (you must type 'c' in the monitor). 4050ERST 4051 4052DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit, 4053 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n" 4054 " run qemu with overcommit hints\n" 4055 " mem-lock=on|off controls memory lock support (default: off)\n" 4056 " cpu-pm=on|off controls cpu power management (default: off)\n", 4057 QEMU_ARCH_ALL) 4058SRST 4059``-overcommit mem-lock=on|off`` 4060 \ 4061``-overcommit cpu-pm=on|off`` 4062 Run qemu with hints about host resource overcommit. The default is 4063 to assume that host overcommits all resources. 4064 4065 Locking qemu and guest memory can be enabled via ``mem-lock=on`` 4066 (disabled by default). This works when host memory is not 4067 overcommitted and reduces the worst-case latency for guest. 4068 4069 Guest ability to manage power state of host cpus (increasing latency 4070 for other processes on the same host cpu, but decreasing latency for 4071 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This 4072 works best when host CPU is not overcommitted. When used, host 4073 estimates of CPU cycle and power utilization will be incorrect, not 4074 taking into account guest idle time. 4075ERST 4076 4077DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \ 4078 "-gdb dev accept gdb connection on 'dev'. (QEMU defaults to starting\n" 4079 " the guest without waiting for gdb to connect; use -S too\n" 4080 " if you want it to not start execution.)\n", 4081 QEMU_ARCH_ALL) 4082SRST 4083``-gdb dev`` 4084 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter 4085 in the System Emulation Users Guide). Note that this option does not pause QEMU 4086 execution -- if you want QEMU to not start the guest until you 4087 connect with gdb and issue a ``continue`` command, you will need to 4088 also pass the ``-S`` option to QEMU. 4089 4090 The most usual configuration is to listen on a local TCP socket:: 4091 4092 -gdb tcp::3117 4093 4094 but you can specify other backends; UDP, pseudo TTY, or even stdio 4095 are all reasonable use cases. For example, a stdio connection 4096 allows you to start QEMU from within gdb and establish the 4097 connection via a pipe: 4098 4099 .. parsed-literal:: 4100 4101 (gdb) target remote | exec |qemu_system| -gdb stdio ... 4102ERST 4103 4104DEF("s", 0, QEMU_OPTION_s, \ 4105 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n", 4106 QEMU_ARCH_ALL) 4107SRST 4108``-s`` 4109 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234 4110 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide). 4111ERST 4112 4113DEF("d", HAS_ARG, QEMU_OPTION_d, \ 4114 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n", 4115 QEMU_ARCH_ALL) 4116SRST 4117``-d item1[,...]`` 4118 Enable logging of specified items. Use '-d help' for a list of log 4119 items. 4120ERST 4121 4122DEF("D", HAS_ARG, QEMU_OPTION_D, \ 4123 "-D logfile output log to logfile (default stderr)\n", 4124 QEMU_ARCH_ALL) 4125SRST 4126``-D logfile`` 4127 Output log in logfile instead of to stderr 4128ERST 4129 4130DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \ 4131 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n", 4132 QEMU_ARCH_ALL) 4133SRST 4134``-dfilter range1[,...]`` 4135 Filter debug output to that relevant to a range of target addresses. 4136 The filter spec can be either start+size, start-size or start..end 4137 where start end and size are the addresses and sizes required. For 4138 example: 4139 4140 :: 4141 4142 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000 4143 4144 Will dump output for any code in the 0x1000 sized block starting at 4145 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and 4146 another 0x1000 sized block starting at 0xffffffc00005f000. 4147ERST 4148 4149DEF("seed", HAS_ARG, QEMU_OPTION_seed, \ 4150 "-seed number seed the pseudo-random number generator\n", 4151 QEMU_ARCH_ALL) 4152SRST 4153``-seed number`` 4154 Force the guest to use a deterministic pseudo-random number 4155 generator, seeded with number. This does not affect crypto routines 4156 within the host. 4157ERST 4158 4159DEF("L", HAS_ARG, QEMU_OPTION_L, \ 4160 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n", 4161 QEMU_ARCH_ALL) 4162SRST 4163``-L path`` 4164 Set the directory for the BIOS, VGA BIOS and keymaps. 4165 4166 To list all the data directories, use ``-L help``. 4167ERST 4168 4169DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ 4170 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) 4171SRST 4172``-bios file`` 4173 Set the filename for the BIOS. 4174ERST 4175 4176DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ 4177 "-enable-kvm enable KVM full virtualization support\n", QEMU_ARCH_ALL) 4178SRST 4179``-enable-kvm`` 4180 Enable KVM full virtualization support. This option is only 4181 available if KVM support is enabled when compiling. 4182ERST 4183 4184DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid, 4185 "-xen-domid id specify xen guest domain id\n", QEMU_ARCH_ALL) 4186DEF("xen-attach", 0, QEMU_OPTION_xen_attach, 4187 "-xen-attach attach to existing xen domain\n" 4188 " libxl will use this when starting QEMU\n", 4189 QEMU_ARCH_ALL) 4190DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict, 4191 "-xen-domid-restrict restrict set of available xen operations\n" 4192 " to specified domain id. (Does not affect\n" 4193 " xenpv machine type).\n", 4194 QEMU_ARCH_ALL) 4195SRST 4196``-xen-domid id`` 4197 Specify xen guest domain id (XEN only). 4198 4199``-xen-attach`` 4200 Attach to existing xen domain. libxl will use this when starting 4201 QEMU (XEN only). Restrict set of available xen operations to 4202 specified domain id (XEN only). 4203ERST 4204 4205DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \ 4206 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL) 4207SRST 4208``-no-reboot`` 4209 Exit instead of rebooting. 4210ERST 4211 4212DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \ 4213 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL) 4214SRST 4215``-no-shutdown`` 4216 Don't exit QEMU on guest shutdown, but instead only stop the 4217 emulation. This allows for instance switching to monitor to commit 4218 changes to the disk image. 4219ERST 4220 4221DEF("action", HAS_ARG, QEMU_OPTION_action, 4222 "-action reboot=reset|shutdown\n" 4223 " action when guest reboots [default=reset]\n" 4224 "-action shutdown=poweroff|pause\n" 4225 " action when guest shuts down [default=poweroff]\n" 4226 "-action panic=pause|shutdown|none\n" 4227 " action when guest panics [default=shutdown]\n" 4228 "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" 4229 " action when watchdog fires [default=reset]\n", 4230 QEMU_ARCH_ALL) 4231SRST 4232``-action event=action`` 4233 The action parameter serves to modify QEMU's default behavior when 4234 certain guest events occur. It provides a generic method for specifying the 4235 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown`` 4236 parameters. 4237 4238 Examples: 4239 4240 ``-action panic=none`` 4241 ``-action reboot=shutdown,shutdown=pause`` 4242 ``-watchdog i6300esb -action watchdog=pause`` 4243 4244ERST 4245 4246DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \ 4247 "-loadvm [tag|id]\n" \ 4248 " start right away with a saved state (loadvm in monitor)\n", 4249 QEMU_ARCH_ALL) 4250SRST 4251``-loadvm file`` 4252 Start right away with a saved state (``loadvm`` in monitor) 4253ERST 4254 4255#ifndef _WIN32 4256DEF("daemonize", 0, QEMU_OPTION_daemonize, \ 4257 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL) 4258#endif 4259SRST 4260``-daemonize`` 4261 Daemonize the QEMU process after initialization. QEMU will not 4262 detach from standard IO until it is ready to receive connections on 4263 any of its devices. This option is a useful way for external 4264 programs to launch QEMU without having to cope with initialization 4265 race conditions. 4266ERST 4267 4268DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \ 4269 "-option-rom rom load a file, rom, into the option ROM space\n", 4270 QEMU_ARCH_ALL) 4271SRST 4272``-option-rom file`` 4273 Load the contents of file as an option ROM. This option is useful to 4274 load things like EtherBoot. 4275ERST 4276 4277DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \ 4278 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \ 4279 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n", 4280 QEMU_ARCH_ALL) 4281 4282SRST 4283``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]`` 4284 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at 4285 the current UTC or local time, respectively. ``localtime`` is 4286 required for correct date in MS-DOS or Windows. To start at a 4287 specific point in time, provide datetime in the format 4288 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC. 4289 4290 By default the RTC is driven by the host system time. This allows 4291 using of the RTC as accurate reference clock inside the guest, 4292 specifically if the host time is smoothly following an accurate 4293 external reference clock, e.g. via NTP. If you want to isolate the 4294 guest time from the host, you can set ``clock`` to ``rt`` instead, 4295 which provides a host monotonic clock if host support it. To even 4296 prevent the RTC from progressing during suspension, you can set 4297 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is 4298 recommended especially in icount mode in order to preserve 4299 determinism; however, note that in icount mode the speed of the 4300 virtual clock is variable and can in general differ from the host 4301 clock. 4302 4303 Enable ``driftfix`` (i386 targets only) if you experience time drift 4304 problems, specifically with Windows' ACPI HAL. This option will try 4305 to figure out how many timer interrupts were not processed by the 4306 Windows guest and will re-inject them. 4307ERST 4308 4309DEF("icount", HAS_ARG, QEMU_OPTION_icount, \ 4310 "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \ 4311 " enable virtual instruction counter with 2^N clock ticks per\n" \ 4312 " instruction, enable aligning the host and virtual clocks\n" \ 4313 " or disable real time cpu sleeping, and optionally enable\n" \ 4314 " record-and-replay mode\n", QEMU_ARCH_ALL) 4315SRST 4316``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]`` 4317 Enable virtual instruction counter. The virtual cpu will execute one 4318 instruction every 2^N ns of virtual time. If ``auto`` is specified 4319 then the virtual cpu speed will be automatically adjusted to keep 4320 virtual time within a few seconds of real time. 4321 4322 Note that while this option can give deterministic behavior, it does 4323 not provide cycle accurate emulation. Modern CPUs contain 4324 superscalar out of order cores with complex cache hierarchies. The 4325 number of instructions executed often has little or no correlation 4326 with actual performance. 4327 4328 When the virtual cpu is sleeping, the virtual time will advance at 4329 default speed unless ``sleep=on`` is specified. With 4330 ``sleep=on``, the virtual time will jump to the next timer 4331 deadline instantly whenever the virtual cpu goes to sleep mode and 4332 will not advance if no timer is enabled. This behavior gives 4333 deterministic execution times from the guest point of view. 4334 The default if icount is enabled is ``sleep=off``. 4335 ``sleep=on`` cannot be used together with either ``shift=auto`` 4336 or ``align=on``. 4337 4338 ``align=on`` will activate the delay algorithm which will try to 4339 synchronise the host clock and the virtual clock. The goal is to 4340 have a guest running at the real frequency imposed by the shift 4341 option. Whenever the guest clock is behind the host clock and if 4342 ``align=on`` is specified then we print a message to the user to 4343 inform about the delay. Currently this option does not work when 4344 ``shift`` is ``auto``. Note: The sync algorithm will work for those 4345 shift values for which the guest clock runs ahead of the host clock. 4346 Typically this happens when the shift value is high (how high 4347 depends on the host machine). The default if icount is enabled 4348 is ``align=off``. 4349 4350 When the ``rr`` option is specified deterministic record/replay is 4351 enabled. The ``rrfile=`` option must also be provided to 4352 specify the path to the replay log. In record mode data is written 4353 to this file, and in replay mode it is read back. 4354 If the ``rrsnapshot`` option is given then it specifies a VM snapshot 4355 name. In record mode, a new VM snapshot with the given name is created 4356 at the start of execution recording. In replay mode this option 4357 specifies the snapshot name used to load the initial VM state. 4358ERST 4359 4360DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \ 4361 "-watchdog model\n" \ 4362 " enable virtual hardware watchdog [default=none]\n", 4363 QEMU_ARCH_ALL) 4364SRST 4365``-watchdog model`` 4366 Create a virtual hardware watchdog device. Once enabled (by a guest 4367 action), the watchdog must be periodically polled by an agent inside 4368 the guest or else the guest will be restarted. Choose a model for 4369 which your guest has drivers. 4370 4371 The model is the model of hardware watchdog to emulate. Use 4372 ``-watchdog help`` to list available hardware models. Only one 4373 watchdog can be enabled for a guest. 4374 4375 The following models may be available: 4376 4377 ``ib700`` 4378 iBASE 700 is a very simple ISA watchdog with a single timer. 4379 4380 ``i6300esb`` 4381 Intel 6300ESB I/O controller hub is a much more featureful 4382 PCI-based dual-timer watchdog. 4383 4384 ``diag288`` 4385 A virtual watchdog for s390x backed by the diagnose 288 4386 hypercall (currently KVM only). 4387ERST 4388 4389DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \ 4390 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \ 4391 " action when watchdog fires [default=reset]\n", 4392 QEMU_ARCH_ALL) 4393SRST 4394``-watchdog-action action`` 4395 The action controls what QEMU will do when the watchdog timer 4396 expires. The default is ``reset`` (forcefully reset the guest). 4397 Other possible actions are: ``shutdown`` (attempt to gracefully 4398 shutdown the guest), ``poweroff`` (forcefully poweroff the guest), 4399 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the 4400 guest), ``debug`` (print a debug message and continue), or ``none`` 4401 (do nothing). 4402 4403 Note that the ``shutdown`` action requires that the guest responds 4404 to ACPI signals, which it may not be able to do in the sort of 4405 situations where the watchdog would have expired, and thus 4406 ``-watchdog-action shutdown`` is not recommended for production use. 4407 4408 Examples: 4409 4410 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700`` 4411 4412ERST 4413 4414DEF("echr", HAS_ARG, QEMU_OPTION_echr, \ 4415 "-echr chr set terminal escape character instead of ctrl-a\n", 4416 QEMU_ARCH_ALL) 4417SRST 4418``-echr numeric_ascii_value`` 4419 Change the escape character used for switching to the monitor when 4420 using monitor and serial sharing. The default is ``0x01`` when using 4421 the ``-nographic`` option. ``0x01`` is equal to pressing 4422 ``Control-a``. You can select a different character from the ascii 4423 control keys where 1 through 26 map to Control-a through Control-z. 4424 For instance you could use the either of the following to change the 4425 escape character to Control-t. 4426 4427 ``-echr 0x14``; \ ``-echr 20`` 4428 4429ERST 4430 4431DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \ 4432 "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \ 4433 "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \ 4434 "-incoming unix:socketpath\n" \ 4435 " prepare for incoming migration, listen on\n" \ 4436 " specified protocol and socket address\n" \ 4437 "-incoming fd:fd\n" \ 4438 "-incoming exec:cmdline\n" \ 4439 " accept incoming migration on given file descriptor\n" \ 4440 " or from given external command\n" \ 4441 "-incoming defer\n" \ 4442 " wait for the URI to be specified via migrate_incoming\n", 4443 QEMU_ARCH_ALL) 4444SRST 4445``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]`` 4446 \ 4447``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]`` 4448 Prepare for incoming migration, listen on a given tcp port. 4449 4450``-incoming unix:socketpath`` 4451 Prepare for incoming migration, listen on a given unix socket. 4452 4453``-incoming fd:fd`` 4454 Accept incoming migration from a given filedescriptor. 4455 4456``-incoming exec:cmdline`` 4457 Accept incoming migration as an output from specified external 4458 command. 4459 4460``-incoming defer`` 4461 Wait for the URI to be specified via migrate\_incoming. The monitor 4462 can be used to change settings (such as migration parameters) prior 4463 to issuing the migrate\_incoming to allow the migration to begin. 4464ERST 4465 4466DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \ 4467 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL) 4468SRST 4469``-only-migratable`` 4470 Only allow migratable devices. Devices will not be allowed to enter 4471 an unmigratable state. 4472ERST 4473 4474DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \ 4475 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL) 4476SRST 4477``-nodefaults`` 4478 Don't create default devices. Normally, QEMU sets the default 4479 devices like serial port, parallel port, virtual console, monitor 4480 device, VGA adapter, floppy and CD-ROM drive and others. The 4481 ``-nodefaults`` option will disable all those default devices. 4482ERST 4483 4484#ifndef _WIN32 4485DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \ 4486 "-chroot dir chroot to dir just before starting the VM\n", 4487 QEMU_ARCH_ALL) 4488#endif 4489SRST 4490``-chroot dir`` 4491 Immediately before starting guest execution, chroot to the specified 4492 directory. Especially useful in combination with -runas. 4493ERST 4494 4495#ifndef _WIN32 4496DEF("runas", HAS_ARG, QEMU_OPTION_runas, \ 4497 "-runas user change to user id user just before starting the VM\n" \ 4498 " user can be numeric uid:gid instead\n", 4499 QEMU_ARCH_ALL) 4500#endif 4501SRST 4502``-runas user`` 4503 Immediately before starting guest execution, drop root privileges, 4504 switching to the specified user. 4505ERST 4506 4507DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env, 4508 "-prom-env variable=value\n" 4509 " set OpenBIOS nvram variables\n", 4510 QEMU_ARCH_PPC | QEMU_ARCH_SPARC) 4511SRST 4512``-prom-env variable=value`` 4513 Set OpenBIOS nvram variable to given value (PPC, SPARC only). 4514 4515 :: 4516 4517 qemu-system-sparc -prom-env 'auto-boot?=false' \ 4518 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single' 4519 4520 :: 4521 4522 qemu-system-ppc -prom-env 'auto-boot?=false' \ 4523 -prom-env 'boot-device=hd:2,\yaboot' \ 4524 -prom-env 'boot-args=conf=hd:2,\yaboot.conf' 4525ERST 4526DEF("semihosting", 0, QEMU_OPTION_semihosting, 4527 "-semihosting semihosting mode\n", 4528 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4529 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4530SRST 4531``-semihosting`` 4532 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only). 4533 4534 Note that this allows guest direct access to the host filesystem, so 4535 should only be used with a trusted guest OS. 4536 4537 See the -semihosting-config option documentation for further 4538 information about the facilities this enables. 4539ERST 4540DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, 4541 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \ 4542 " semihosting configuration\n", 4543QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4544QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4545SRST 4546``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]`` 4547 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V 4548 only). 4549 4550 Note that this allows guest direct access to the host filesystem, so 4551 should only be used with a trusted guest OS. 4552 4553 On Arm this implements the standard semihosting API, version 2.0. 4554 4555 On M68K this implements the "ColdFire GDB" interface used by 4556 libgloss. 4557 4558 Xtensa semihosting provides basic file IO calls, such as 4559 open/read/write/seek/select. Tensilica baremetal libc for ISS and 4560 linux platform "sim" use this interface. 4561 4562 On RISC-V this implements the standard semihosting API, version 0.2. 4563 4564 ``target=native|gdb|auto`` 4565 Defines where the semihosting calls will be addressed, to QEMU 4566 (``native``) or to GDB (``gdb``). The default is ``auto``, which 4567 means ``gdb`` during debug sessions and ``native`` otherwise. 4568 4569 ``chardev=str1`` 4570 Send the output to a chardev backend output for native or auto 4571 output when not in gdb 4572 4573 ``arg=str1,arg=str2,...`` 4574 Allows the user to pass input arguments, and can be used 4575 multiple times to build up a list. The old-style 4576 ``-kernel``/``-append`` method of passing a command line is 4577 still supported for backward compatibility. If both the 4578 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are 4579 specified, the former is passed to semihosting as it always 4580 takes precedence. 4581ERST 4582DEF("old-param", 0, QEMU_OPTION_old_param, 4583 "-old-param old param mode\n", QEMU_ARCH_ARM) 4584SRST 4585``-old-param`` 4586 Old param mode (ARM only). 4587ERST 4588 4589DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ 4590 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ 4591 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \ 4592 " Enable seccomp mode 2 system call filter (default 'off').\n" \ 4593 " use 'obsolete' to allow obsolete system calls that are provided\n" \ 4594 " by the kernel, but typically no longer used by modern\n" \ 4595 " C library implementations.\n" \ 4596 " use 'elevateprivileges' to allow or deny the QEMU process ability\n" \ 4597 " to elevate privileges using set*uid|gid system calls.\n" \ 4598 " The value 'children' will deny set*uid|gid system calls for\n" \ 4599 " main QEMU process but will allow forks and execves to run unprivileged\n" \ 4600 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \ 4601 " blocking *fork and execve\n" \ 4602 " use 'resourcecontrol' to disable process affinity and schedular priority\n", 4603 QEMU_ARCH_ALL) 4604SRST 4605``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]`` 4606 Enable Seccomp mode 2 system call filter. 'on' will enable syscall 4607 filtering and 'off' will disable it. The default is 'off'. 4608 4609 ``obsolete=string`` 4610 Enable Obsolete system calls 4611 4612 ``elevateprivileges=string`` 4613 Disable set\*uid\|gid system calls 4614 4615 ``spawn=string`` 4616 Disable \*fork and execve 4617 4618 ``resourcecontrol=string`` 4619 Disable process affinity and schedular priority 4620ERST 4621 4622DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig, 4623 "-readconfig <file>\n", QEMU_ARCH_ALL) 4624SRST 4625``-readconfig file`` 4626 Read device configuration from file. This approach is useful when 4627 you want to spawn QEMU process with many command line options but 4628 you don't want to exceed the command line character limit. 4629ERST 4630DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig, 4631 "-writeconfig <file>\n" 4632 " read/write config file (deprecated)\n", QEMU_ARCH_ALL) 4633SRST 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 4674#ifdef __linux__ 4675DEF("enable-fips", 0, QEMU_OPTION_enablefips, 4676 "-enable-fips enable FIPS 140-2 compliance\n", 4677 QEMU_ARCH_ALL) 4678#endif 4679SRST 4680``-enable-fips`` 4681 Enable FIPS 140-2 compliance mode. 4682ERST 4683 4684DEF("msg", HAS_ARG, QEMU_OPTION_msg, 4685 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n" 4686 " control error message format\n" 4687 " timestamp=on enables timestamps (default: off)\n" 4688 " guest-name=on enables guest name prefix but only if\n" 4689 " -name guest option is set (default: off)\n", 4690 QEMU_ARCH_ALL) 4691SRST 4692``-msg [timestamp[=on|off]][,guest-name[=on|off]]`` 4693 Control error message format. 4694 4695 ``timestamp=on|off`` 4696 Prefix messages with a timestamp. Default is off. 4697 4698 ``guest-name=on|off`` 4699 Prefix messages with guest name but only if -name guest option is set 4700 otherwise the option is ignored. Default is off. 4701ERST 4702 4703DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate, 4704 "-dump-vmstate <file>\n" 4705 " Output vmstate information in JSON format to file.\n" 4706 " Use the scripts/vmstate-static-checker.py file to\n" 4707 " check for possible regressions in migration code\n" 4708 " by comparing two such vmstate dumps.\n", 4709 QEMU_ARCH_ALL) 4710SRST 4711``-dump-vmstate file`` 4712 Dump json-encoded vmstate information for current machine type to 4713 file in file 4714ERST 4715 4716DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile, 4717 "-enable-sync-profile\n" 4718 " enable synchronization profiling\n", 4719 QEMU_ARCH_ALL) 4720SRST 4721``-enable-sync-profile`` 4722 Enable synchronization profiling. 4723ERST 4724 4725DEFHEADING() 4726 4727DEFHEADING(Generic object creation:) 4728 4729DEF("object", HAS_ARG, QEMU_OPTION_object, 4730 "-object TYPENAME[,PROP1=VALUE1,...]\n" 4731 " create a new object of type TYPENAME setting properties\n" 4732 " in the order they are specified. Note that the 'id'\n" 4733 " property must be set. These objects are placed in the\n" 4734 " '/objects' path.\n", 4735 QEMU_ARCH_ALL) 4736SRST 4737``-object typename[,prop1=value1,...]`` 4738 Create a new object of type typename setting properties in the order 4739 they are specified. Note that the 'id' property must be set. These 4740 objects are placed in the '/objects' path. 4741 4742 ``-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`` 4743 Creates a memory file backend object, which can be used to back 4744 the guest RAM with huge pages. 4745 4746 The ``id`` parameter is a unique ID that will be used to 4747 reference this memory region in other parameters, e.g. ``-numa``, 4748 ``-device nvdimm``, etc. 4749 4750 The ``size`` option provides the size of the memory region, and 4751 accepts common suffixes, e.g. ``500M``. 4752 4753 The ``mem-path`` provides the path to either a shared memory or 4754 huge page filesystem mount. 4755 4756 The ``share`` boolean option determines whether the memory 4757 region is marked as private to QEMU, or shared. The latter 4758 allows a co-operating external process to access the QEMU memory 4759 region. 4760 4761 The ``share`` is also required for pvrdma devices due to 4762 limitations in the RDMA API provided by Linux. 4763 4764 Setting share=on might affect the ability to configure NUMA 4765 bindings for the memory backend under some circumstances, see 4766 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel 4767 source tree for additional details. 4768 4769 Setting the ``discard-data`` boolean option to on indicates that 4770 file contents can be destroyed when QEMU exits, to avoid 4771 unnecessarily flushing data to the backing file. Note that 4772 ``discard-data`` is only an optimization, and QEMU might not 4773 discard file contents if it aborts unexpectedly or is terminated 4774 using SIGKILL. 4775 4776 The ``merge`` boolean option enables memory merge, also known as 4777 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider 4778 the pages for memory deduplication. 4779 4780 Setting the ``dump`` boolean option to off excludes the memory 4781 from core dumps. This feature is also known as MADV\_DONTDUMP. 4782 4783 The ``prealloc`` boolean option enables memory preallocation. 4784 4785 The ``host-nodes`` option binds the memory range to a list of 4786 NUMA host nodes. 4787 4788 The ``policy`` option sets the NUMA policy to one of the 4789 following values: 4790 4791 ``default`` 4792 default host policy 4793 4794 ``preferred`` 4795 prefer the given host node list for allocation 4796 4797 ``bind`` 4798 restrict memory allocation to the given host node list 4799 4800 ``interleave`` 4801 interleave memory allocations across the given host node 4802 list 4803 4804 The ``align`` option specifies the base address alignment when 4805 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg 4806 ``2M``. Some backend store specified by ``mem-path`` requires an 4807 alignment different than the default one used by QEMU, eg the 4808 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In 4809 such cases, users can specify the required alignment via this 4810 option. 4811 4812 The ``pmem`` option specifies whether the backing file specified 4813 by ``mem-path`` is in host persistent memory that can be 4814 accessed using the SNIA NVM programming model (e.g. Intel 4815 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary 4816 operations to guarantee the persistence of its own writes to 4817 ``mem-path`` (e.g. in vNVDIMM label emulation and live 4818 migration). Also, we will map the backend-file with MAP\_SYNC 4819 flag, which ensures the file metadata is in sync for 4820 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC 4821 requires support from both the host kernel (since Linux kernel 4822 4.15) and the filesystem of ``mem-path`` mounted with DAX 4823 option. 4824 4825 The ``readonly`` option specifies whether the backing file is opened 4826 read-only or read-write (default). 4827 4828 ``-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`` 4829 Creates a memory backend object, which can be used to back the 4830 guest RAM. Memory backend objects offer more control than the 4831 ``-m`` option that is traditionally used to define guest RAM. 4832 Please refer to ``memory-backend-file`` for a description of the 4833 options. 4834 4835 ``-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`` 4836 Creates an anonymous memory file backend object, which allows 4837 QEMU to share the memory with an external process (e.g. when 4838 using vhost-user). The memory is allocated with memfd and 4839 optional sealing. (Linux only) 4840 4841 The ``seal`` option creates a sealed-file, that will block 4842 further resizing the memory ('on' by default). 4843 4844 The ``hugetlb`` option specify the file to be created resides in 4845 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction 4846 with the ``hugetlb`` option, the ``hugetlbsize`` option specify 4847 the hugetlb page size on systems that support multiple hugetlb 4848 page sizes (it must be a power of 2 value supported by the 4849 system). 4850 4851 In some versions of Linux, the ``hugetlb`` option is 4852 incompatible with the ``seal`` option (requires at least Linux 4853 4.16). 4854 4855 Please refer to ``memory-backend-file`` for a description of the 4856 other options. 4857 4858 The ``share`` boolean option is on by default with memfd. 4859 4860 ``-object rng-builtin,id=id`` 4861 Creates a random number generator backend which obtains entropy 4862 from QEMU builtin functions. The ``id`` parameter is a unique ID 4863 that will be used to reference this entropy backend from the 4864 ``virtio-rng`` device. By default, the ``virtio-rng`` device 4865 uses this RNG backend. 4866 4867 ``-object rng-random,id=id,filename=/dev/random`` 4868 Creates a random number generator backend which obtains entropy 4869 from a device on the host. The ``id`` parameter is a unique ID 4870 that will be used to reference this entropy backend from the 4871 ``virtio-rng`` device. The ``filename`` parameter specifies 4872 which file to obtain entropy from and if omitted defaults to 4873 ``/dev/urandom``. 4874 4875 ``-object rng-egd,id=id,chardev=chardevid`` 4876 Creates a random number generator backend which obtains entropy 4877 from an external daemon running on the host. The ``id`` 4878 parameter is a unique ID that will be used to reference this 4879 entropy backend from the ``virtio-rng`` device. The ``chardev`` 4880 parameter is the unique ID of a character device backend that 4881 provides the connection to the RNG daemon. 4882 4883 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off`` 4884 Creates a TLS anonymous credentials object, which can be used to 4885 provide TLS support on network backends. The ``id`` parameter is 4886 a unique ID which network backends will use to access the 4887 credentials. The ``endpoint`` is either ``server`` or ``client`` 4888 depending on whether the QEMU network backend that uses the 4889 credentials will be acting as a client or as a server. If 4890 ``verify-peer`` is enabled (the default) then once the handshake 4891 is completed, the peer credentials will be verified, though this 4892 is a no-op for anonymous credentials. 4893 4894 The dir parameter tells QEMU where to find the credential files. 4895 For server endpoints, this directory may contain a file 4896 dh-params.pem providing diffie-hellman parameters to use for the 4897 TLS server. If the file is missing, QEMU will generate a set of 4898 DH parameters at startup. This is a computationally expensive 4899 operation that consumes random pool entropy, so it is 4900 recommended that a persistent set of parameters be generated 4901 upfront and saved. 4902 4903 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]`` 4904 Creates a TLS Pre-Shared Keys (PSK) credentials object, which 4905 can be used to provide TLS support on network backends. The 4906 ``id`` parameter is a unique ID which network backends will use 4907 to access the credentials. The ``endpoint`` is either ``server`` 4908 or ``client`` depending on whether the QEMU network backend that 4909 uses the credentials will be acting as a client or as a server. 4910 For clients only, ``username`` is the username which will be 4911 sent to the server. If omitted it defaults to "qemu". 4912 4913 The dir parameter tells QEMU where to find the keys file. It is 4914 called "dir/keys.psk" and contains "username:key" pairs. This 4915 file can most easily be created using the GnuTLS ``psktool`` 4916 program. 4917 4918 For server endpoints, dir may also contain a file dh-params.pem 4919 providing diffie-hellman parameters to use for the TLS server. 4920 If the file is missing, QEMU will generate a set of DH 4921 parameters at startup. This is a computationally expensive 4922 operation that consumes random pool entropy, so it is 4923 recommended that a persistent set of parameters be generated up 4924 front and saved. 4925 4926 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id`` 4927 Creates a TLS anonymous credentials object, which can be used to 4928 provide TLS support on network backends. The ``id`` parameter is 4929 a unique ID which network backends will use to access the 4930 credentials. The ``endpoint`` is either ``server`` or ``client`` 4931 depending on whether the QEMU network backend that uses the 4932 credentials will be acting as a client or as a server. If 4933 ``verify-peer`` is enabled (the default) then once the handshake 4934 is completed, the peer credentials will be verified. With x509 4935 certificates, this implies that the clients must be provided 4936 with valid client certificates too. 4937 4938 The dir parameter tells QEMU where to find the credential files. 4939 For server endpoints, this directory may contain a file 4940 dh-params.pem providing diffie-hellman parameters to use for the 4941 TLS server. If the file is missing, QEMU will generate a set of 4942 DH parameters at startup. This is a computationally expensive 4943 operation that consumes random pool entropy, so it is 4944 recommended that a persistent set of parameters be generated 4945 upfront and saved. 4946 4947 For x509 certificate credentials the directory will contain 4948 further files providing the x509 certificates. The certificates 4949 must be stored in PEM format, in filenames ca-cert.pem, 4950 ca-crl.pem (optional), server-cert.pem (only servers), 4951 server-key.pem (only servers), client-cert.pem (only clients), 4952 and client-key.pem (only clients). 4953 4954 For the server-key.pem and client-key.pem files which contain 4955 sensitive private keys, it is possible to use an encrypted 4956 version by providing the passwordid parameter. This provides the 4957 ID of a previously created ``secret`` object containing the 4958 password for decryption. 4959 4960 The priority parameter allows to override the global default 4961 priority used by gnutls. This can be useful if the system 4962 administrator needs to use a weaker set of crypto priorities for 4963 QEMU without potentially forcing the weakness onto all 4964 applications. Or conversely if one wants wants a stronger 4965 default for QEMU than for all other applications, they can do 4966 this through this parameter. Its format is a gnutls priority 4967 string as described at 4968 https://gnutls.org/manual/html_node/Priority-Strings.html. 4969 4970 ``-object tls-cipher-suites,id=id,priority=priority`` 4971 Creates a TLS cipher suites object, which can be used to control 4972 the TLS cipher/protocol algorithms that applications are permitted 4973 to use. 4974 4975 The ``id`` parameter is a unique ID which frontends will use to 4976 access the ordered list of permitted TLS cipher suites from the 4977 host. 4978 4979 The ``priority`` parameter allows to override the global default 4980 priority used by gnutls. This can be useful if the system 4981 administrator needs to use a weaker set of crypto priorities for 4982 QEMU without potentially forcing the weakness onto all 4983 applications. Or conversely if one wants wants a stronger 4984 default for QEMU than for all other applications, they can do 4985 this through this parameter. Its format is a gnutls priority 4986 string as described at 4987 https://gnutls.org/manual/html_node/Priority-Strings.html. 4988 4989 An example of use of this object is to control UEFI HTTPS Boot. 4990 The tls-cipher-suites object exposes the ordered list of permitted 4991 TLS cipher suites from the host side to the guest firmware, via 4992 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER 4993 objects. The firmware uses the IANA_TLS_CIPHER array for configuring 4994 guest-side TLS. 4995 4996 In the following example, the priority at which the host-side policy 4997 is retrieved is given by the ``priority`` property. 4998 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to 4999 refer to /etc/crypto-policies/back-ends/gnutls.config. 5000 5001 .. parsed-literal:: 5002 5003 # |qemu_system| \\ 5004 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\ 5005 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0 5006 5007 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]`` 5008 Interval t can't be 0, this filter batches the packet delivery: 5009 all packets arriving in a given interval on netdev netdevid are 5010 delayed until the end of the interval. Interval is in 5011 microseconds. ``status`` is optional that indicate whether the 5012 netfilter is on (enabled) or off (disabled), the default status 5013 for netfilter will be 'on'. 5014 5015 queue all\|rx\|tx is an option that can be applied to any 5016 netfilter. 5017 5018 ``all``: the filter is attached both to the receive and the 5019 transmit queue of the netdev (default). 5020 5021 ``rx``: the filter is attached to the receive queue of the 5022 netdev, where it will receive packets sent to the netdev. 5023 5024 ``tx``: the filter is attached to the transmit queue of the 5025 netdev, where it will receive packets sent by the netdev. 5026 5027 position head\|tail\|id=<id> is an option to specify where the 5028 filter should be inserted in the filter list. It can be applied 5029 to any netfilter. 5030 5031 ``head``: the filter is inserted at the head of the filter list, 5032 before any existing filters. 5033 5034 ``tail``: the filter is inserted at the tail of the filter list, 5035 behind any existing filters (default). 5036 5037 ``id=<id>``: the filter is inserted before or behind the filter 5038 specified by <id>, see the insert option below. 5039 5040 insert behind\|before is an option to specify where to insert 5041 the new filter relative to the one specified with 5042 position=id=<id>. It can be applied to any netfilter. 5043 5044 ``before``: insert before the specified filter. 5045 5046 ``behind``: insert behind the specified filter (default). 5047 5048 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5049 filter-mirror on netdev netdevid,mirror net packet to 5050 chardevchardevid, if it has the vnet\_hdr\_support flag, 5051 filter-mirror will mirror packet with vnet\_hdr\_len. 5052 5053 ``-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]`` 5054 filter-redirector on netdev netdevid,redirect filter's net 5055 packet to chardev chardevid,and redirect indev's packet to 5056 filter.if it has the vnet\_hdr\_support flag, filter-redirector 5057 will redirect packet with vnet\_hdr\_len. Create a 5058 filter-redirector we need to differ outdev id from indev id, id 5059 can not be the same. we can just use indev or outdev, but at 5060 least one of indev or outdev need to be specified. 5061 5062 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5063 Filter-rewriter is a part of COLO project.It will rewrite tcp 5064 packet to secondary from primary to keep secondary tcp 5065 connection,and rewrite tcp packet to primary from secondary make 5066 tcp packet can be handled by client.if it has the 5067 vnet\_hdr\_support flag, we can parse packet with vnet header. 5068 5069 usage: colo secondary: -object 5070 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object 5071 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object 5072 filter-rewriter,id=rew0,netdev=hn0,queue=all 5073 5074 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]`` 5075 Dump the network traffic on netdev dev to the file specified by 5076 filename. At most len bytes (64k by default) per packet are 5077 stored. The file format is libpcap, so it can be analyzed with 5078 tools such as tcpdump or Wireshark. 5079 5080 ``-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}]`` 5081 Colo-compare gets packet from primary\_in chardevid and 5082 secondary\_in, then compare whether the payload of primary packet 5083 and secondary packet are the same. If same, it will output 5084 primary packet to out\_dev, else it will notify COLO-framework to do 5085 checkpoint and send primary packet to out\_dev. In order to 5086 improve efficiency, we need to put the task of comparison in 5087 another iothread. If it has the vnet\_hdr\_support flag, 5088 colo compare will send/recv packet with vnet\_hdr\_len. 5089 The compare\_timeout=@var{ms} determines the maximum time of the 5090 colo-compare hold the packet. The expired\_scan\_cycle=@var{ms} 5091 is to set the period of scanning expired primary node network packets. 5092 The max\_queue\_size=@var{size} is to set the max compare queue 5093 size depend on user environment. 5094 If user want to use Xen COLO, need to add the notify\_dev to 5095 notify Xen colo-frame to do checkpoint. 5096 5097 COLO-compare must be used with the help of filter-mirror, 5098 filter-redirector and filter-rewriter. 5099 5100 :: 5101 5102 KVM COLO 5103 5104 primary: 5105 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5106 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5107 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5108 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5109 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5110 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5111 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5112 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5113 -object iothread,id=iothread1 5114 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5115 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5116 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5117 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1 5118 5119 secondary: 5120 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5121 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5122 -chardev socket,id=red0,host=3.3.3.3,port=9003 5123 -chardev socket,id=red1,host=3.3.3.3,port=9004 5124 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5125 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5126 5127 5128 Xen COLO 5129 5130 primary: 5131 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5132 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5133 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5134 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5135 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5136 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5137 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5138 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5139 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server=on,wait=off 5140 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5141 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5142 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5143 -object iothread,id=iothread1 5144 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1 5145 5146 secondary: 5147 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5148 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5149 -chardev socket,id=red0,host=3.3.3.3,port=9003 5150 -chardev socket,id=red1,host=3.3.3.3,port=9004 5151 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5152 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5153 5154 If you want to know the detail of above command line, you can 5155 read the colo-compare git log. 5156 5157 ``-object cryptodev-backend-builtin,id=id[,queues=queues]`` 5158 Creates a cryptodev backend which executes crypto opreation from 5159 the QEMU cipher APIS. The id parameter is a unique ID that will 5160 be used to reference this cryptodev backend from the 5161 ``virtio-crypto`` device. The queues parameter is optional, 5162 which specify the queue number of cryptodev backend, the default 5163 of queues is 1. 5164 5165 .. parsed-literal:: 5166 5167 # |qemu_system| \\ 5168 [...] \\ 5169 -object cryptodev-backend-builtin,id=cryptodev0 \\ 5170 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5171 [...] 5172 5173 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]`` 5174 Creates a vhost-user cryptodev backend, backed by a chardev 5175 chardevid. The id parameter is a unique ID that will be used to 5176 reference this cryptodev backend from the ``virtio-crypto`` 5177 device. The chardev should be a unix domain socket backed one. 5178 The vhost-user uses a specifically defined protocol to pass 5179 vhost ioctl replacement messages to an application on the other 5180 end of the socket. The queues parameter is optional, which 5181 specify the queue number of cryptodev backend for multiqueue 5182 vhost-user, the default of queues is 1. 5183 5184 .. parsed-literal:: 5185 5186 # |qemu_system| \\ 5187 [...] \\ 5188 -chardev socket,id=chardev0,path=/path/to/socket \\ 5189 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\ 5190 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5191 [...] 5192 5193 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]`` 5194 \ 5195 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]`` 5196 Defines a secret to store a password, encryption key, or some 5197 other sensitive data. The sensitive data can either be passed 5198 directly via the data parameter, or indirectly via the file 5199 parameter. Using the data parameter is insecure unless the 5200 sensitive data is encrypted. 5201 5202 The sensitive data can be provided in raw format (the default), 5203 or base64. When encoded as JSON, the raw format only supports 5204 valid UTF-8 characters, so base64 is recommended for sending 5205 binary data. QEMU will convert from which ever format is 5206 provided to the format it needs internally. eg, an RBD password 5207 can be provided in raw format, even though it will be base64 5208 encoded when passed onto the RBD sever. 5209 5210 For added protection, it is possible to encrypt the data 5211 associated with a secret using the AES-256-CBC cipher. Use of 5212 encryption is indicated by providing the keyid and iv 5213 parameters. The keyid parameter provides the ID of a previously 5214 defined secret that contains the AES-256 decryption key. This 5215 key should be 32-bytes long and be base64 encoded. The iv 5216 parameter provides the random initialization vector used for 5217 encryption of this particular secret and should be a base64 5218 encrypted string of the 16-byte IV. 5219 5220 The simplest (insecure) usage is to provide the secret inline 5221 5222 .. parsed-literal:: 5223 5224 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw 5225 5226 The simplest secure usage is to provide the secret via a file 5227 5228 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object 5229 secret,id=sec0,file=mypasswd.txt,format=raw 5230 5231 For greater security, AES-256-CBC should be used. To illustrate 5232 usage, consider the openssl command line tool which can encrypt 5233 the data. Note that when encrypting, the plaintext must be 5234 padded to the cipher block size (32 bytes) using the standard 5235 PKCS#5/6 compatible padding algorithm. 5236 5237 First a master key needs to be created in base64 encoding: 5238 5239 :: 5240 5241 # openssl rand -base64 32 > key.b64 5242 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"') 5243 5244 Each secret to be encrypted needs to have a random 5245 initialization vector generated. These do not need to be kept 5246 secret 5247 5248 :: 5249 5250 # openssl rand -base64 16 > iv.b64 5251 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"') 5252 5253 The secret to be defined can now be encrypted, in this case 5254 we're telling openssl to base64 encode the result, but it could 5255 be left as raw bytes if desired. 5256 5257 :: 5258 5259 # SECRET=$(printf "letmein" | 5260 openssl enc -aes-256-cbc -a -K $KEY -iv $IV) 5261 5262 When launching QEMU, create a master secret pointing to 5263 ``key.b64`` and specify that to be used to decrypt the user 5264 password. Pass the contents of ``iv.b64`` to the second secret 5265 5266 .. parsed-literal:: 5267 5268 # |qemu_system| \\ 5269 -object secret,id=secmaster0,format=base64,file=key.b64 \\ 5270 -object secret,id=sec0,keyid=secmaster0,format=base64,\\ 5271 data=$SECRET,iv=$(<iv.b64) 5272 5273 ``-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]`` 5274 Create a Secure Encrypted Virtualization (SEV) guest object, 5275 which can be used to provide the guest memory encryption support 5276 on AMD processors. 5277 5278 When memory encryption is enabled, one of the physical address 5279 bit (aka the C-bit) is utilized to mark if a memory page is 5280 protected. The ``cbitpos`` is used to provide the C-bit 5281 position. The C-bit position is Host family dependent hence user 5282 must provide this value. On EPYC, the value should be 47. 5283 5284 When memory encryption is enabled, we loose certain bits in 5285 physical address space. The ``reduced-phys-bits`` is used to 5286 provide the number of bits we loose in physical address space. 5287 Similar to C-bit, the value is Host family dependent. On EPYC, 5288 the value should be 5. 5289 5290 The ``sev-device`` provides the device file to use for 5291 communicating with the SEV firmware running inside AMD Secure 5292 Processor. The default device is '/dev/sev'. If hardware 5293 supports memory encryption then /dev/sev devices are created by 5294 CCP driver. 5295 5296 The ``policy`` provides the guest policy to be enforced by the 5297 SEV firmware and restrict what configuration and operational 5298 commands can be performed on this guest by the hypervisor. The 5299 policy should be provided by the guest owner and is bound to the 5300 guest and cannot be changed throughout the lifetime of the 5301 guest. The default is 0. 5302 5303 If guest ``policy`` allows sharing the key with another SEV 5304 guest then ``handle`` can be use to provide handle of the guest 5305 from which to share the key. 5306 5307 The ``dh-cert-file`` and ``session-file`` provides the guest 5308 owner's Public Diffie-Hillman key defined in SEV spec. The PDH 5309 and session parameters are used for establishing a cryptographic 5310 session with the guest owner to negotiate keys used for 5311 attestation. The file must be encoded in base64. 5312 5313 The ``kernel-hashes`` adds the hashes of given kernel/initrd/ 5314 cmdline to a designated guest firmware page for measured Linux 5315 boot with -kernel. The default is off. (Since 6.2) 5316 5317 e.g to launch a SEV guest 5318 5319 .. parsed-literal:: 5320 5321 # |qemu_system_x86| \\ 5322 ...... \\ 5323 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\ 5324 -machine ...,memory-encryption=sev0 \\ 5325 ..... 5326 5327 ``-object authz-simple,id=id,identity=string`` 5328 Create an authorization object that will control access to 5329 network services. 5330 5331 The ``identity`` parameter is identifies the user and its format 5332 depends on the network service that authorization object is 5333 associated with. For authorizing based on TLS x509 certificates, 5334 the identity must be the x509 distinguished name. Note that care 5335 must be taken to escape any commas in the distinguished name. 5336 5337 An example authorization object to validate a x509 distinguished 5338 name would look like: 5339 5340 .. parsed-literal:: 5341 5342 # |qemu_system| \\ 5343 ... \\ 5344 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\ 5345 ... 5346 5347 Note the use of quotes due to the x509 distinguished name 5348 containing whitespace, and escaping of ','. 5349 5350 ``-object authz-listfile,id=id,filename=path,refresh=on|off`` 5351 Create an authorization object that will control access to 5352 network services. 5353 5354 The ``filename`` parameter is the fully qualified path to a file 5355 containing the access control list rules in JSON format. 5356 5357 An example set of rules that match against SASL usernames might 5358 look like: 5359 5360 :: 5361 5362 { 5363 "rules": [ 5364 { "match": "fred", "policy": "allow", "format": "exact" }, 5365 { "match": "bob", "policy": "allow", "format": "exact" }, 5366 { "match": "danb", "policy": "deny", "format": "glob" }, 5367 { "match": "dan*", "policy": "allow", "format": "exact" }, 5368 ], 5369 "policy": "deny" 5370 } 5371 5372 When checking access the object will iterate over all the rules 5373 and the first rule to match will have its ``policy`` value 5374 returned as the result. If no rules match, then the default 5375 ``policy`` value is returned. 5376 5377 The rules can either be an exact string match, or they can use 5378 the simple UNIX glob pattern matching to allow wildcards to be 5379 used. 5380 5381 If ``refresh`` is set to true the file will be monitored and 5382 automatically reloaded whenever its content changes. 5383 5384 As with the ``authz-simple`` object, the format of the identity 5385 strings being matched depends on the network service, but is 5386 usually a TLS x509 distinguished name, or a SASL username. 5387 5388 An example authorization object to validate a SASL username 5389 would look like: 5390 5391 .. parsed-literal:: 5392 5393 # |qemu_system| \\ 5394 ... \\ 5395 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\ 5396 ... 5397 5398 ``-object authz-pam,id=id,service=string`` 5399 Create an authorization object that will control access to 5400 network services. 5401 5402 The ``service`` parameter provides the name of a PAM service to 5403 use for authorization. It requires that a file 5404 ``/etc/pam.d/service`` exist to provide the configuration for 5405 the ``account`` subsystem. 5406 5407 An example authorization object to validate a TLS x509 5408 distinguished name would look like: 5409 5410 .. parsed-literal:: 5411 5412 # |qemu_system| \\ 5413 ... \\ 5414 -object authz-pam,id=auth0,service=qemu-vnc \\ 5415 ... 5416 5417 There would then be a corresponding config file for PAM at 5418 ``/etc/pam.d/qemu-vnc`` that contains: 5419 5420 :: 5421 5422 account requisite pam_listfile.so item=user sense=allow \ 5423 file=/etc/qemu/vnc.allow 5424 5425 Finally the ``/etc/qemu/vnc.allow`` file would contain the list 5426 of x509 distingished names that are permitted access 5427 5428 :: 5429 5430 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB 5431 5432 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch`` 5433 Creates a dedicated event loop thread that devices can be 5434 assigned to. This is known as an IOThread. By default device 5435 emulation happens in vCPU threads or the main event loop thread. 5436 This can become a scalability bottleneck. IOThreads allow device 5437 emulation and I/O to run on other host CPUs. 5438 5439 The ``id`` parameter is a unique ID that will be used to 5440 reference this IOThread from ``-device ...,iothread=id``. 5441 Multiple devices can be assigned to an IOThread. Note that not 5442 all devices support an ``iothread`` parameter. 5443 5444 The ``query-iothreads`` QMP command lists IOThreads and reports 5445 their thread IDs so that the user can configure host CPU 5446 pinning/affinity. 5447 5448 IOThreads use an adaptive polling algorithm to reduce event loop 5449 latency. Instead of entering a blocking system call to monitor 5450 file descriptors and then pay the cost of being woken up when an 5451 event occurs, the polling algorithm spins waiting for events for 5452 a short time. The algorithm's default parameters are suitable 5453 for many cases but can be adjusted based on knowledge of the 5454 workload and/or host device latency. 5455 5456 The ``poll-max-ns`` parameter is the maximum number of 5457 nanoseconds to busy wait for events. Polling can be disabled by 5458 setting this value to 0. 5459 5460 The ``poll-grow`` parameter is the multiplier used to increase 5461 the polling time when the algorithm detects it is missing events 5462 due to not polling long enough. 5463 5464 The ``poll-shrink`` parameter is the divisor used to decrease 5465 the polling time when the algorithm detects it is spending too 5466 long polling without encountering events. 5467 5468 The ``aio-max-batch`` parameter is the maximum number of requests 5469 in a batch for the AIO engine, 0 means that the engine will use 5470 its default. 5471 5472 The IOThread parameters can be modified at run-time using the 5473 ``qom-set`` command (where ``iothread1`` is the IOThread's 5474 ``id``): 5475 5476 :: 5477 5478 (qemu) qom-set /objects/iothread1 poll-max-ns 100000 5479ERST 5480 5481 5482HXCOMM This is the last statement. Insert new options before this line! 5483 5484#undef DEF 5485#undef DEFHEADING 5486#undef ARCHHEADING 5487
