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 " cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n", 41 QEMU_ARCH_ALL) 42SRST 43``-machine [type=]name[,prop=value[,...]]`` 44 Select the emulated machine by name. Use ``-machine help`` to list 45 available machines. 46 47 For architectures which aim to support live migration compatibility 48 across releases, each release will introduce a new versioned machine 49 type. For example, the 2.8.0 release introduced machine types 50 "pc-i440fx-2.8" and "pc-q35-2.8" for the x86\_64/i686 architectures. 51 52 To allow live migration of guests from QEMU version 2.8.0, to QEMU 53 version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8" 54 and "pc-q35-2.8" machines too. To allow users live migrating VMs to 55 skip multiple intermediate releases when upgrading, new releases of 56 QEMU will support machine types from many previous versions. 57 58 Supported machine properties are: 59 60 ``accel=accels1[:accels2[:...]]`` 61 This is used to enable an accelerator. Depending on the target 62 architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available. 63 By default, tcg is used. If there is more than one accelerator 64 specified, the next one is used if the previous one fails to 65 initialize. 66 67 ``vmport=on|off|auto`` 68 Enables emulation of VMWare IO port, for vmmouse etc. auto says 69 to select the value based on accel. For accel=xen the default is 70 off otherwise the default is on. 71 72 ``dump-guest-core=on|off`` 73 Include guest memory in a core dump. The default is on. 74 75 ``mem-merge=on|off`` 76 Enables or disables memory merge support. This feature, when 77 supported by the host, de-duplicates identical memory pages 78 among VMs instances (enabled by default). 79 80 ``aes-key-wrap=on|off`` 81 Enables or disables AES key wrapping support on s390-ccw hosts. 82 This feature controls whether AES wrapping keys will be created 83 to allow execution of AES cryptographic functions. The default 84 is on. 85 86 ``dea-key-wrap=on|off`` 87 Enables or disables DEA key wrapping support on s390-ccw hosts. 88 This feature controls whether DEA wrapping keys will be created 89 to allow execution of DEA cryptographic functions. The default 90 is on. 91 92 ``nvdimm=on|off`` 93 Enables or disables NVDIMM support. The default is off. 94 95 ``memory-encryption=`` 96 Memory encryption object to use. The default is none. 97 98 ``hmat=on|off`` 99 Enables or disables ACPI Heterogeneous Memory Attribute Table 100 (HMAT) support. The default is off. 101 102 ``memory-backend='id'`` 103 An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options. 104 Allows to use a memory backend as main RAM. 105 106 For example: 107 :: 108 109 -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on 110 -machine memory-backend=pc.ram 111 -m 512M 112 113 Migration compatibility note: 114 115 * as backend id one shall use value of 'default-ram-id', advertised by 116 machine type (available via ``query-machines`` QMP command), if migration 117 to/from old QEMU (<5.0) is expected. 118 * for machine types 4.0 and older, user shall 119 use ``x-use-canonical-path-for-ramblock-id=off`` backend option 120 if migration to/from old QEMU (<5.0) is expected. 121 122 For example: 123 :: 124 125 -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off 126 -machine memory-backend=pc.ram 127 -m 512M 128 129 ``cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]`` 130 Define a CXL Fixed Memory Window (CFMW). 131 132 Described in the CXL 2.0 ECN: CEDT CFMWS & QTG _DSM. 133 134 They are regions of Host Physical Addresses (HPA) on a system which 135 may be interleaved across one or more CXL host bridges. The system 136 software will assign particular devices into these windows and 137 configure the downstream Host-managed Device Memory (HDM) decoders 138 in root ports, switch ports and devices appropriately to meet the 139 interleave requirements before enabling the memory devices. 140 141 ``targets.X=target`` provides the mapping to CXL host bridges 142 which may be identified by the id provied in the -device entry. 143 Multiple entries are needed to specify all the targets when 144 the fixed memory window represents interleaved memory. X is the 145 target index from 0. 146 147 ``size=size`` sets the size of the CFMW. This must be a multiple of 148 256MiB. The region will be aligned to 256MiB but the location is 149 platform and configuration dependent. 150 151 ``interleave-granularity=granularity`` sets the granularity of 152 interleave. Default 256KiB. Only 256KiB, 512KiB, 1024KiB, 2048KiB 153 4096KiB, 8192KiB and 16384KiB granularities supported. 154 155 Example: 156 157 :: 158 159 -machine cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.targets.1=cxl.1,cxl-fmw.0.size=128G,cxl-fmw.0.interleave-granularity=512k 160ERST 161 162DEF("M", HAS_ARG, QEMU_OPTION_M, 163 " sgx-epc.0.memdev=memid,sgx-epc.0.node=numaid\n", 164 QEMU_ARCH_ALL) 165 166SRST 167``sgx-epc.0.memdev=@var{memid},sgx-epc.0.node=@var{numaid}`` 168 Define an SGX EPC section. 169ERST 170 171DEF("cpu", HAS_ARG, QEMU_OPTION_cpu, 172 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL) 173SRST 174``-cpu model`` 175 Select CPU model (``-cpu help`` for list and additional feature 176 selection) 177ERST 178 179DEF("accel", HAS_ARG, QEMU_OPTION_accel, 180 "-accel [accel=]accelerator[,prop[=value][,...]]\n" 181 " select accelerator (kvm, xen, hax, hvf, nvmm, whpx or tcg; use 'help' for a list)\n" 182 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n" 183 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n" 184 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n" 185 " split-wx=on|off (enable TCG split w^x mapping)\n" 186 " tb-size=n (TCG translation block cache size)\n" 187 " dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n" 188 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL) 189SRST 190``-accel name[,prop=value[,...]]`` 191 This is used to enable an accelerator. Depending on the target 192 architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available. By 193 default, tcg is used. If there is more than one accelerator 194 specified, the next one is used if the previous one fails to 195 initialize. 196 197 ``igd-passthru=on|off`` 198 When Xen is in use, this option controls whether Intel 199 integrated graphics devices can be passed through to the guest 200 (default=off) 201 202 ``kernel-irqchip=on|off|split`` 203 Controls KVM in-kernel irqchip support. The default is full 204 acceleration of the interrupt controllers. On x86, split irqchip 205 reduces the kernel attack surface, at a performance cost for 206 non-MSI interrupts. Disabling the in-kernel irqchip completely 207 is not recommended except for debugging purposes. 208 209 ``kvm-shadow-mem=size`` 210 Defines the size of the KVM shadow MMU. 211 212 ``split-wx=on|off`` 213 Controls the use of split w^x mapping for the TCG code generation 214 buffer. Some operating systems require this to be enabled, and in 215 such a case this will default on. On other operating systems, this 216 will default off, but one may enable this for testing or debugging. 217 218 ``tb-size=n`` 219 Controls the size (in MiB) of the TCG translation block cache. 220 221 ``thread=single|multi`` 222 Controls number of TCG threads. When the TCG is multi-threaded 223 there will be one thread per vCPU therefore taking advantage of 224 additional host cores. The default is to enable multi-threading 225 where both the back-end and front-ends support it and no 226 incompatible TCG features have been enabled (e.g. 227 icount/replay). 228 229 ``dirty-ring-size=n`` 230 When the KVM accelerator is used, it controls the size of the per-vCPU 231 dirty page ring buffer (number of entries for each vCPU). It should 232 be a value that is power of two, and it should be 1024 or bigger (but 233 still less than the maximum value that the kernel supports). 4096 234 could be a good initial value if you have no idea which is the best. 235 Set this value to 0 to disable the feature. By default, this feature 236 is disabled (dirty-ring-size=0). When enabled, KVM will instead 237 record dirty pages in a bitmap. 238 239ERST 240 241DEF("smp", HAS_ARG, QEMU_OPTION_smp, 242 "-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]\n" 243 " set the number of initial CPUs to 'n' [default=1]\n" 244 " maxcpus= maximum number of total CPUs, including\n" 245 " offline CPUs for hotplug, etc\n" 246 " sockets= number of sockets on the machine board\n" 247 " dies= number of dies in one socket\n" 248 " clusters= number of clusters in one die\n" 249 " cores= number of cores in one cluster\n" 250 " threads= number of threads in one core\n" 251 "Note: Different machines may have different subsets of the CPU topology\n" 252 " parameters supported, so the actual meaning of the supported parameters\n" 253 " will vary accordingly. For example, for a machine type that supports a\n" 254 " three-level CPU hierarchy of sockets/cores/threads, the parameters will\n" 255 " sequentially mean as below:\n" 256 " sockets means the number of sockets on the machine board\n" 257 " cores means the number of cores in one socket\n" 258 " threads means the number of threads in one core\n" 259 " For a particular machine type board, an expected CPU topology hierarchy\n" 260 " can be defined through the supported sub-option. Unsupported parameters\n" 261 " can also be provided in addition to the sub-option, but their values\n" 262 " must be set as 1 in the purpose of correct parsing.\n", 263 QEMU_ARCH_ALL) 264SRST 265``-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]`` 266 Simulate a SMP system with '\ ``n``\ ' CPUs initially present on 267 the machine type board. On boards supporting CPU hotplug, the optional 268 '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be 269 added at runtime. When both parameters are omitted, the maximum number 270 of CPUs will be calculated from the provided topology members and the 271 initial CPU count will match the maximum number. When only one of them 272 is given then the omitted one will be set to its counterpart's value. 273 Both parameters may be specified, but the maximum number of CPUs must 274 be equal to or greater than the initial CPU count. Product of the 275 CPU topology hierarchy must be equal to the maximum number of CPUs. 276 Both parameters are subject to an upper limit that is determined by 277 the specific machine type chosen. 278 279 To control reporting of CPU topology information, values of the topology 280 parameters can be specified. Machines may only support a subset of the 281 parameters and different machines may have different subsets supported 282 which vary depending on capacity of the corresponding CPU targets. So 283 for a particular machine type board, an expected topology hierarchy can 284 be defined through the supported sub-option. Unsupported parameters can 285 also be provided in addition to the sub-option, but their values must be 286 set as 1 in the purpose of correct parsing. 287 288 Either the initial CPU count, or at least one of the topology parameters 289 must be specified. The specified parameters must be greater than zero, 290 explicit configuration like "cpus=0" is not allowed. Values for any 291 omitted parameters will be computed from those which are given. 292 293 For example, the following sub-option defines a CPU topology hierarchy 294 (2 sockets totally on the machine, 2 cores per socket, 2 threads per 295 core) for a machine that only supports sockets/cores/threads. 296 Some members of the option can be omitted but their values will be 297 automatically computed: 298 299 :: 300 301 -smp 8,sockets=2,cores=2,threads=2,maxcpus=8 302 303 The following sub-option defines a CPU topology hierarchy (2 sockets 304 totally on the machine, 2 dies per socket, 2 cores per die, 2 threads 305 per core) for PC machines which support sockets/dies/cores/threads. 306 Some members of the option can be omitted but their values will be 307 automatically computed: 308 309 :: 310 311 -smp 16,sockets=2,dies=2,cores=2,threads=2,maxcpus=16 312 313 The following sub-option defines a CPU topology hierarchy (2 sockets 314 totally on the machine, 2 clusters per socket, 2 cores per cluster, 315 2 threads per core) for ARM virt machines which support sockets/clusters 316 /cores/threads. Some members of the option can be omitted but their values 317 will be automatically computed: 318 319 :: 320 321 -smp 16,sockets=2,clusters=2,cores=2,threads=2,maxcpus=16 322 323 Historically preference was given to the coarsest topology parameters 324 when computing missing values (ie sockets preferred over cores, which 325 were preferred over threads), however, this behaviour is considered 326 liable to change. Prior to 6.2 the preference was sockets over cores 327 over threads. Since 6.2 the preference is cores over sockets over threads. 328 329 For example, the following option defines a machine board with 2 sockets 330 of 1 core before 6.2 and 1 socket of 2 cores after 6.2: 331 332 :: 333 334 -smp 2 335ERST 336 337DEF("numa", HAS_ARG, QEMU_OPTION_numa, 338 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 339 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 340 "-numa dist,src=source,dst=destination,val=distance\n" 341 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n" 342 "-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" 343 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n", 344 QEMU_ARCH_ALL) 345SRST 346``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 347 \ 348``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 349 \ 350``-numa dist,src=source,dst=destination,val=distance`` 351 \ 352``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]`` 353 \ 354``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]`` 355 \ 356``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]`` 357 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA 358 distance from a source node to a destination node. Set the ACPI 359 Heterogeneous Memory Attributes for the given nodes. 360 361 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and 362 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a 363 contiguous range of CPU indexes (or a single VCPU if lastcpu is 364 omitted). A non-contiguous set of VCPUs can be represented by 365 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is 366 omitted on all nodes, VCPUs are automatically split between them. 367 368 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a 369 NUMA node: 370 371 :: 372 373 -numa node,cpus=0-2,cpus=5 374 375 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option 376 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to 377 assign CPU objects to a node using topology layout properties of 378 CPU. The set of properties is machine specific, and depends on used 379 machine type/'\ ``smp``\ ' options. It could be queried with 380 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ ' 381 property specifies node to which CPU object will be assigned, it's 382 required for node to be declared with '\ ``node``\ ' option before 383 it's used with '\ ``cpu``\ ' option. 384 385 For example: 386 387 :: 388 389 -M pc \ 390 -smp 1,sockets=2,maxcpus=2 \ 391 -numa node,nodeid=0 -numa node,nodeid=1 \ 392 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1 393 394 Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported 395 for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from 396 a given memory backend device to a node. If '\ ``mem``\ ' and 397 '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them. 398 399 400 '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive. 401 Furthermore, if one node uses '\ ``memdev``\ ', all of them have to 402 use it. 403 404 '\ ``initiator``\ ' is an additional option that points to an 405 initiator NUMA node that has best performance (the lowest latency or 406 largest bandwidth) to this NUMA node. Note that this option can be 407 set only when the machine property 'hmat' is set to 'on'. 408 409 Following example creates a machine with 2 NUMA nodes, node 0 has 410 CPU. node 1 has only memory, and its initiator is node 0. Note that 411 because node 0 has CPU, by default the initiator of node 0 is itself 412 and must be itself. 413 414 :: 415 416 -machine hmat=on \ 417 -m 2G,slots=2,maxmem=4G \ 418 -object memory-backend-ram,size=1G,id=m0 \ 419 -object memory-backend-ram,size=1G,id=m1 \ 420 -numa node,nodeid=0,memdev=m0 \ 421 -numa node,nodeid=1,memdev=m1,initiator=0 \ 422 -smp 2,sockets=2,maxcpus=2 \ 423 -numa cpu,node-id=0,socket-id=0 \ 424 -numa cpu,node-id=0,socket-id=1 425 426 source and destination are NUMA node IDs. distance is the NUMA 427 distance from source to destination. The distance from a node to 428 itself is always 10. If any pair of nodes is given a distance, then 429 all pairs must be given distances. Although, when distances are only 430 given in one direction for each pair of nodes, then the distances in 431 the opposite directions are assumed to be the same. If, however, an 432 asymmetrical pair of distances is given for even one node pair, then 433 all node pairs must be provided distance values for both directions, 434 even when they are symmetrical. When a node is unreachable from 435 another node, set the pair's distance to 255. 436 437 Note that the -``numa`` option doesn't allocate any of the specified 438 resources, it just assigns existing resources to NUMA nodes. This 439 means that one still has to use the ``-m``, ``-smp`` options to 440 allocate RAM and VCPUs respectively. 441 442 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth 443 Information between initiator and target NUMA nodes in ACPI 444 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can 445 create memory requests, usually it has one or more processors. 446 Target NUMA node contains addressable memory. 447 448 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is 449 the memory hierarchy of the target NUMA node: if hierarchy is 450 'memory', the structure represents the memory performance; if 451 hierarchy is 'first-level\|second-level\|third-level', this 452 structure represents aggregated performance of memory side caches 453 for each domain. type of 'data-type' is type of data represented by 454 this structure instance: if 'hierarchy' is 'memory', 'data-type' is 455 'access\|read\|write' latency or 'access\|read\|write' bandwidth of 456 the target memory; if 'hierarchy' is 457 'first-level\|second-level\|third-level', 'data-type' is 458 'access\|read\|write' hit latency or 'access\|read\|write' hit 459 bandwidth of the target memory side cache. 460 461 lat is latency value in nanoseconds. bw is bandwidth value, the 462 possible value and units are NUM[M\|G\|T], mean that the bandwidth 463 value are NUM byte per second (or MB/s, GB/s or TB/s depending on 464 used suffix). Note that if latency or bandwidth value is 0, means 465 the corresponding latency or bandwidth information is not provided. 466 467 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory 468 belongs. size is the size of memory side cache in bytes. level is 469 the cache level described in this structure, note that the cache 470 level 0 should not be used with '\ ``hmat-cache``\ ' option. 471 associativity is the cache associativity, the possible value is 472 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy 473 is the write policy. line is the cache Line size in bytes. 474 475 For example, the following options describe 2 NUMA nodes. Node 0 has 476 2 cpus and a ram, node 1 has only a ram. The processors in node 0 477 access memory in node 0 with access-latency 5 nanoseconds, 478 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access 479 memory in NUMA node 1 with access-latency 10 nanoseconds, 480 access-bandwidth is 100 MB/s. And for memory side cache information, 481 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB, 482 policy is write-back, the cache Line size is 8 bytes: 483 484 :: 485 486 -machine hmat=on \ 487 -m 2G \ 488 -object memory-backend-ram,size=1G,id=m0 \ 489 -object memory-backend-ram,size=1G,id=m1 \ 490 -smp 2,sockets=2,maxcpus=2 \ 491 -numa node,nodeid=0,memdev=m0 \ 492 -numa node,nodeid=1,memdev=m1,initiator=0 \ 493 -numa cpu,node-id=0,socket-id=0 \ 494 -numa cpu,node-id=0,socket-id=1 \ 495 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \ 496 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \ 497 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \ 498 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \ 499 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \ 500 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8 501ERST 502 503DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd, 504 "-add-fd fd=fd,set=set[,opaque=opaque]\n" 505 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL) 506SRST 507``-add-fd fd=fd,set=set[,opaque=opaque]`` 508 Add a file descriptor to an fd set. Valid options are: 509 510 ``fd=fd`` 511 This option defines the file descriptor of which a duplicate is 512 added to fd set. The file descriptor cannot be stdin, stdout, or 513 stderr. 514 515 ``set=set`` 516 This option defines the ID of the fd set to add the file 517 descriptor to. 518 519 ``opaque=opaque`` 520 This option defines a free-form string that can be used to 521 describe fd. 522 523 You can open an image using pre-opened file descriptors from an fd 524 set: 525 526 .. parsed-literal:: 527 528 |qemu_system| \\ 529 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 530 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 531 -drive file=/dev/fdset/2,index=0,media=disk 532ERST 533 534DEF("set", HAS_ARG, QEMU_OPTION_set, 535 "-set group.id.arg=value\n" 536 " set <arg> parameter for item <id> of type <group>\n" 537 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL) 538SRST 539``-set group.id.arg=value`` 540 Set parameter arg for item id of type group 541ERST 542 543DEF("global", HAS_ARG, QEMU_OPTION_global, 544 "-global driver.property=value\n" 545 "-global driver=driver,property=property,value=value\n" 546 " set a global default for a driver property\n", 547 QEMU_ARCH_ALL) 548SRST 549``-global driver.prop=value`` 550 \ 551``-global driver=driver,property=property,value=value`` 552 Set default value of driver's property prop to value, e.g.: 553 554 .. parsed-literal:: 555 556 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img 557 558 In particular, you can use this to set driver properties for devices 559 which are created automatically by the machine model. To create a 560 device which is not created automatically and set properties on it, 561 use -``device``. 562 563 -global driver.prop=value is shorthand for -global 564 driver=driver,property=prop,value=value. The longhand syntax works 565 even when driver contains a dot. 566ERST 567 568DEF("boot", HAS_ARG, QEMU_OPTION_boot, 569 "-boot [order=drives][,once=drives][,menu=on|off]\n" 570 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n" 571 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n" 572 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n" 573 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n" 574 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n", 575 QEMU_ARCH_ALL) 576SRST 577``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]`` 578 Specify boot order drives as a string of drive letters. Valid drive 579 letters depend on the target architecture. The x86 PC uses: a, b 580 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p 581 (Etherboot from network adapter 1-4), hard disk boot is the default. 582 To apply a particular boot order only on the first startup, specify 583 it via ``once``. Note that the ``order`` or ``once`` parameter 584 should not be used together with the ``bootindex`` property of 585 devices, since the firmware implementations normally do not support 586 both at the same time. 587 588 Interactive boot menus/prompts can be enabled via ``menu=on`` as far 589 as firmware/BIOS supports them. The default is non-interactive boot. 590 591 A splash picture could be passed to bios, enabling user to show it 592 as logo, when option splash=sp\_name is given and menu=on, If 593 firmware/BIOS supports them. Currently Seabios for X86 system 594 support it. limitation: The splash file could be a jpeg file or a 595 BMP file in 24 BPP format(true color). The resolution should be 596 supported by the SVGA mode, so the recommended is 320x240, 640x480, 597 800x640. 598 599 A timeout could be passed to bios, guest will pause for rb\_timeout 600 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will 601 not reboot, qemu passes '-1' to bios by default. Currently Seabios 602 for X86 system support it. 603 604 Do strict boot via ``strict=on`` as far as firmware/BIOS supports 605 it. This only effects when boot priority is changed by bootindex 606 options. The default is non-strict boot. 607 608 .. parsed-literal:: 609 610 # try to boot from network first, then from hard disk 611 |qemu_system_x86| -boot order=nc 612 # boot from CD-ROM first, switch back to default order after reboot 613 |qemu_system_x86| -boot once=d 614 # boot with a splash picture for 5 seconds. 615 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000 616 617 Note: The legacy format '-boot drives' is still supported but its 618 use is discouraged as it may be removed from future versions. 619ERST 620 621DEF("m", HAS_ARG, QEMU_OPTION_m, 622 "-m [size=]megs[,slots=n,maxmem=size]\n" 623 " configure guest RAM\n" 624 " size: initial amount of guest memory\n" 625 " slots: number of hotplug slots (default: none)\n" 626 " maxmem: maximum amount of guest memory (default: none)\n" 627 "NOTE: Some architectures might enforce a specific granularity\n", 628 QEMU_ARCH_ALL) 629SRST 630``-m [size=]megs[,slots=n,maxmem=size]`` 631 Sets guest startup RAM size to megs megabytes. Default is 128 MiB. 632 Optionally, a suffix of "M" or "G" can be used to signify a value in 633 megabytes or gigabytes respectively. Optional pair slots, maxmem 634 could be used to set amount of hotpluggable memory slots and maximum 635 amount of memory. Note that maxmem must be aligned to the page size. 636 637 For example, the following command-line sets the guest startup RAM 638 size to 1GB, creates 3 slots to hotplug additional memory and sets 639 the maximum memory the guest can reach to 4GB: 640 641 .. parsed-literal:: 642 643 |qemu_system| -m 1G,slots=3,maxmem=4G 644 645 If slots and maxmem are not specified, memory hotplug won't be 646 enabled and the guest startup RAM will never increase. 647ERST 648 649DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath, 650 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL) 651SRST 652``-mem-path path`` 653 Allocate guest RAM from a temporarily created file in path. 654ERST 655 656DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc, 657 "-mem-prealloc preallocate guest memory (use with -mem-path)\n", 658 QEMU_ARCH_ALL) 659SRST 660``-mem-prealloc`` 661 Preallocate memory when using -mem-path. 662ERST 663 664DEF("k", HAS_ARG, QEMU_OPTION_k, 665 "-k language use keyboard layout (for example 'fr' for French)\n", 666 QEMU_ARCH_ALL) 667SRST 668``-k language`` 669 Use keyboard layout language (for example ``fr`` for French). This 670 option is only needed where it is not easy to get raw PC keycodes 671 (e.g. on Macs, with some X11 servers or with a VNC or curses 672 display). You don't normally need to use it on PC/Linux or 673 PC/Windows hosts. 674 675 The available layouts are: 676 677 :: 678 679 ar de-ch es fo fr-ca hu ja mk no pt-br sv 680 da en-gb et fr fr-ch is lt nl pl ru th 681 de en-us fi fr-be hr it lv nl-be pt sl tr 682 683 The default is ``en-us``. 684ERST 685 686 687HXCOMM Deprecated by -audiodev 688DEF("audio-help", 0, QEMU_OPTION_audio_help, 689 "-audio-help show -audiodev equivalent of the currently specified audio settings\n", 690 QEMU_ARCH_ALL) 691SRST 692``-audio-help`` 693 Will show the -audiodev equivalent of the currently specified 694 (deprecated) environment variables. 695ERST 696 697DEF("audio", HAS_ARG, QEMU_OPTION_audio, 698 "-audio [driver=]driver,model=value[,prop[=value][,...]]\n" 699 " specifies the audio backend and device to use;\n" 700 " apart from 'model', options are the same as for -audiodev.\n" 701 " use '-audio model=help' to show possible devices.\n", 702 QEMU_ARCH_ALL) 703SRST 704``-audio [driver=]driver,model=value[,prop[=value][,...]]`` 705 This option is a shortcut for configuring both the guest audio 706 hardware and the host audio backend in one go. 707 The host backend options are the same as with the corresponding 708 ``-audiodev`` options below. The guest hardware model can be set with 709 ``model=modelname``. Use ``model=help`` to list the available device 710 types. 711 712 The following two example do exactly the same, to show how ``-audio`` 713 can be used to shorten the command line length: 714 715 .. parsed-literal:: 716 717 |qemu_system| -audiodev pa,id=pa -device sb16,audiodev=pa 718 |qemu_system| -audio pa,model=sb16 719ERST 720 721DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev, 722 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n" 723 " specifies the audio backend to use\n" 724 " id= identifier of the backend\n" 725 " timer-period= timer period in microseconds\n" 726 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n" 727 " in|out.fixed-settings= use fixed settings for host audio\n" 728 " in|out.frequency= frequency to use with fixed settings\n" 729 " in|out.channels= number of channels to use with fixed settings\n" 730 " in|out.format= sample format to use with fixed settings\n" 731 " valid values: s8, s16, s32, u8, u16, u32, f32\n" 732 " in|out.voices= number of voices to use\n" 733 " in|out.buffer-length= length of buffer in microseconds\n" 734 "-audiodev none,id=id,[,prop[=value][,...]]\n" 735 " dummy driver that discards all output\n" 736#ifdef CONFIG_AUDIO_ALSA 737 "-audiodev alsa,id=id[,prop[=value][,...]]\n" 738 " in|out.dev= name of the audio device to use\n" 739 " in|out.period-length= length of period in microseconds\n" 740 " in|out.try-poll= attempt to use poll mode\n" 741 " threshold= threshold (in microseconds) when playback starts\n" 742#endif 743#ifdef CONFIG_AUDIO_COREAUDIO 744 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n" 745 " in|out.buffer-count= number of buffers\n" 746#endif 747#ifdef CONFIG_AUDIO_DSOUND 748 "-audiodev dsound,id=id[,prop[=value][,...]]\n" 749 " latency= add extra latency to playback in microseconds\n" 750#endif 751#ifdef CONFIG_AUDIO_OSS 752 "-audiodev oss,id=id[,prop[=value][,...]]\n" 753 " in|out.dev= path of the audio device to use\n" 754 " in|out.buffer-count= number of buffers\n" 755 " in|out.try-poll= attempt to use poll mode\n" 756 " try-mmap= try using memory mapped access\n" 757 " exclusive= open device in exclusive mode\n" 758 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n" 759#endif 760#ifdef CONFIG_AUDIO_PA 761 "-audiodev pa,id=id[,prop[=value][,...]]\n" 762 " server= PulseAudio server address\n" 763 " in|out.name= source/sink device name\n" 764 " in|out.latency= desired latency in microseconds\n" 765#endif 766#ifdef CONFIG_AUDIO_SDL 767 "-audiodev sdl,id=id[,prop[=value][,...]]\n" 768 " in|out.buffer-count= number of buffers\n" 769#endif 770#ifdef CONFIG_SPICE 771 "-audiodev spice,id=id[,prop[=value][,...]]\n" 772#endif 773#ifdef CONFIG_DBUS_DISPLAY 774 "-audiodev dbus,id=id[,prop[=value][,...]]\n" 775#endif 776 "-audiodev wav,id=id[,prop[=value][,...]]\n" 777 " path= path of wav file to record\n", 778 QEMU_ARCH_ALL) 779SRST 780``-audiodev [driver=]driver,id=id[,prop[=value][,...]]`` 781 Adds a new audio backend driver identified by id. There are global 782 and driver specific properties. Some values can be set differently 783 for input and output, they're marked with ``in|out.``. You can set 784 the input's property with ``in.prop`` and the output's property with 785 ``out.prop``. For example: 786 787 :: 788 789 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000 790 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified 791 792 NOTE: parameter validation is known to be incomplete, in many cases 793 specifying an invalid option causes QEMU to print an error message 794 and continue emulation without sound. 795 796 Valid global options are: 797 798 ``id=identifier`` 799 Identifies the audio backend. 800 801 ``timer-period=period`` 802 Sets the timer period used by the audio subsystem in 803 microseconds. Default is 10000 (10 ms). 804 805 ``in|out.mixing-engine=on|off`` 806 Use QEMU's mixing engine to mix all streams inside QEMU and 807 convert audio formats when not supported by the backend. When 808 off, fixed-settings must be off too. Note that disabling this 809 option means that the selected backend must support multiple 810 streams and the audio formats used by the virtual cards, 811 otherwise you'll get no sound. It's not recommended to disable 812 this option unless you want to use 5.1 or 7.1 audio, as mixing 813 engine only supports mono and stereo audio. Default is on. 814 815 ``in|out.fixed-settings=on|off`` 816 Use fixed settings for host audio. When off, it will change 817 based on how the guest opens the sound card. In this case you 818 must not specify frequency, channels or format. Default is on. 819 820 ``in|out.frequency=frequency`` 821 Specify the frequency to use when using fixed-settings. Default 822 is 44100Hz. 823 824 ``in|out.channels=channels`` 825 Specify the number of channels to use when using fixed-settings. 826 Default is 2 (stereo). 827 828 ``in|out.format=format`` 829 Specify the sample format to use when using fixed-settings. 830 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``, 831 ``u32``, ``f32``. Default is ``s16``. 832 833 ``in|out.voices=voices`` 834 Specify the number of voices to use. Default is 1. 835 836 ``in|out.buffer-length=usecs`` 837 Sets the size of the buffer in microseconds. 838 839``-audiodev none,id=id[,prop[=value][,...]]`` 840 Creates a dummy backend that discards all outputs. This backend has 841 no backend specific properties. 842 843``-audiodev alsa,id=id[,prop[=value][,...]]`` 844 Creates backend using the ALSA. This backend is only available on 845 Linux. 846 847 ALSA specific options are: 848 849 ``in|out.dev=device`` 850 Specify the ALSA device to use for input and/or output. Default 851 is ``default``. 852 853 ``in|out.period-length=usecs`` 854 Sets the period length in microseconds. 855 856 ``in|out.try-poll=on|off`` 857 Attempt to use poll mode with the device. Default is on. 858 859 ``threshold=threshold`` 860 Threshold (in microseconds) when playback starts. Default is 0. 861 862``-audiodev coreaudio,id=id[,prop[=value][,...]]`` 863 Creates a backend using Apple's Core Audio. This backend is only 864 available on Mac OS and only supports playback. 865 866 Core Audio specific options are: 867 868 ``in|out.buffer-count=count`` 869 Sets the count of the buffers. 870 871``-audiodev dsound,id=id[,prop[=value][,...]]`` 872 Creates a backend using Microsoft's DirectSound. This backend is 873 only available on Windows and only supports playback. 874 875 DirectSound specific options are: 876 877 ``latency=usecs`` 878 Add extra usecs microseconds latency to playback. Default is 879 10000 (10 ms). 880 881``-audiodev oss,id=id[,prop[=value][,...]]`` 882 Creates a backend using OSS. This backend is available on most 883 Unix-like systems. 884 885 OSS specific options are: 886 887 ``in|out.dev=device`` 888 Specify the file name of the OSS device to use. Default is 889 ``/dev/dsp``. 890 891 ``in|out.buffer-count=count`` 892 Sets the count of the buffers. 893 894 ``in|out.try-poll=on|of`` 895 Attempt to use poll mode with the device. Default is on. 896 897 ``try-mmap=on|off`` 898 Try using memory mapped device access. Default is off. 899 900 ``exclusive=on|off`` 901 Open the device in exclusive mode (vmix won't work in this 902 case). Default is off. 903 904 ``dsp-policy=policy`` 905 Sets the timing policy (between 0 and 10, where smaller number 906 means smaller latency but higher CPU usage). Use -1 to use 907 buffer sizes specified by ``buffer`` and ``buffer-count``. This 908 option is ignored if you do not have OSS 4. Default is 5. 909 910``-audiodev pa,id=id[,prop[=value][,...]]`` 911 Creates a backend using PulseAudio. This backend is available on 912 most systems. 913 914 PulseAudio specific options are: 915 916 ``server=server`` 917 Sets the PulseAudio server to connect to. 918 919 ``in|out.name=sink`` 920 Use the specified source/sink for recording/playback. 921 922 ``in|out.latency=usecs`` 923 Desired latency in microseconds. The PulseAudio server will try 924 to honor this value but actual latencies may be lower or higher. 925 926``-audiodev sdl,id=id[,prop[=value][,...]]`` 927 Creates a backend using SDL. This backend is available on most 928 systems, but you should use your platform's native backend if 929 possible. 930 931 SDL specific options are: 932 933 ``in|out.buffer-count=count`` 934 Sets the count of the buffers. 935 936``-audiodev spice,id=id[,prop[=value][,...]]`` 937 Creates a backend that sends audio through SPICE. This backend 938 requires ``-spice`` and automatically selected in that case, so 939 usually you can ignore this option. This backend has no backend 940 specific properties. 941 942``-audiodev wav,id=id[,prop[=value][,...]]`` 943 Creates a backend that writes audio to a WAV file. 944 945 Backend specific options are: 946 947 ``path=path`` 948 Write recorded audio into the specified file. Default is 949 ``qemu.wav``. 950ERST 951 952DEF("device", HAS_ARG, QEMU_OPTION_device, 953 "-device driver[,prop[=value][,...]]\n" 954 " add device (based on driver)\n" 955 " prop=value,... sets driver properties\n" 956 " use '-device help' to print all possible drivers\n" 957 " use '-device driver,help' to print all possible properties\n", 958 QEMU_ARCH_ALL) 959SRST 960``-device driver[,prop[=value][,...]]`` 961 Add device driver. prop=value sets driver properties. Valid 962 properties depend on the driver. To get help on possible drivers and 963 properties, use ``-device help`` and ``-device driver,help``. 964 965 Some drivers are: 966 967``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]`` 968 Add an IPMI BMC. This is a simulation of a hardware management 969 interface processor that normally sits on a system. It provides a 970 watchdog and the ability to reset and power control the system. You 971 need to connect this to an IPMI interface to make it useful 972 973 The IPMI slave address to use for the BMC. The default is 0x20. This 974 address is the BMC's address on the I2C network of management 975 controllers. If you don't know what this means, it is safe to ignore 976 it. 977 978 ``id=id`` 979 The BMC id for interfaces to use this device. 980 981 ``slave_addr=val`` 982 Define slave address to use for the BMC. The default is 0x20. 983 984 ``sdrfile=file`` 985 file containing raw Sensor Data Records (SDR) data. The default 986 is none. 987 988 ``fruareasize=val`` 989 size of a Field Replaceable Unit (FRU) area. The default is 990 1024. 991 992 ``frudatafile=file`` 993 file containing raw Field Replaceable Unit (FRU) inventory data. 994 The default is none. 995 996 ``guid=uuid`` 997 value for the GUID for the BMC, in standard UUID format. If this 998 is set, get "Get GUID" command to the BMC will return it. 999 Otherwise "Get GUID" will return an error. 1000 1001``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]`` 1002 Add a connection to an external IPMI BMC simulator. Instead of 1003 locally emulating the BMC like the above item, instead connect to an 1004 external entity that provides the IPMI services. 1005 1006 A connection is made to an external BMC simulator. If you do this, 1007 it is strongly recommended that you use the "reconnect=" chardev 1008 option to reconnect to the simulator if the connection is lost. Note 1009 that if this is not used carefully, it can be a security issue, as 1010 the interface has the ability to send resets, NMIs, and power off 1011 the VM. It's best if QEMU makes a connection to an external 1012 simulator running on a secure port on localhost, so neither the 1013 simulator nor QEMU is exposed to any outside network. 1014 1015 See the "lanserv/README.vm" file in the OpenIPMI library for more 1016 details on the external interface. 1017 1018``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]`` 1019 Add a KCS IPMI interafce on the ISA bus. This also adds a 1020 corresponding ACPI and SMBIOS entries, if appropriate. 1021 1022 ``bmc=id`` 1023 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern 1024 above. 1025 1026 ``ioport=val`` 1027 Define the I/O address of the interface. The default is 0xca0 1028 for KCS. 1029 1030 ``irq=val`` 1031 Define the interrupt to use. The default is 5. To disable 1032 interrupts, set this to 0. 1033 1034``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]`` 1035 Like the KCS interface, but defines a BT interface. The default port 1036 is 0xe4 and the default interrupt is 5. 1037 1038``-device pci-ipmi-kcs,bmc=id`` 1039 Add a KCS IPMI interafce on the PCI bus. 1040 1041 ``bmc=id`` 1042 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above. 1043 1044``-device pci-ipmi-bt,bmc=id`` 1045 Like the KCS interface, but defines a BT interface on the PCI bus. 1046 1047``-device intel-iommu[,option=...]`` 1048 This is only supported by ``-machine q35``, which will enable Intel VT-d 1049 emulation within the guest. It supports below options: 1050 1051 ``intremap=on|off`` (default: auto) 1052 This enables interrupt remapping feature. It's required to enable 1053 complete x2apic. Currently it only supports kvm kernel-irqchip modes 1054 ``off`` or ``split``, while full kernel-irqchip is not yet supported. 1055 The default value is "auto", which will be decided by the mode of 1056 kernel-irqchip. 1057 1058 ``caching-mode=on|off`` (default: off) 1059 This enables caching mode for the VT-d emulated device. When 1060 caching-mode is enabled, each guest DMA buffer mapping will generate an 1061 IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in 1062 a synchronous way. It is required for ``-device vfio-pci`` to work 1063 with the VT-d device, because host assigned devices requires to setup 1064 the DMA mapping on the host before guest DMA starts. 1065 1066 ``device-iotlb=on|off`` (default: off) 1067 This enables device-iotlb capability for the emulated VT-d device. So 1068 far virtio/vhost should be the only real user for this parameter, 1069 paired with ats=on configured for the device. 1070 1071 ``aw-bits=39|48`` (default: 39) 1072 This decides the address width of IOVA address space. The address 1073 space has 39 bits width for 3-level IOMMU page tables, and 48 bits for 1074 4-level IOMMU page tables. 1075 1076 Please also refer to the wiki page for general scenarios of VT-d 1077 emulation in QEMU: https://wiki.qemu.org/Features/VT-d. 1078 1079ERST 1080 1081DEF("name", HAS_ARG, QEMU_OPTION_name, 1082 "-name string1[,process=string2][,debug-threads=on|off]\n" 1083 " set the name of the guest\n" 1084 " string1 sets the window title and string2 the process name\n" 1085 " When debug-threads is enabled, individual threads are given a separate name\n" 1086 " NOTE: The thread names are for debugging and not a stable API.\n", 1087 QEMU_ARCH_ALL) 1088SRST 1089``-name name`` 1090 Sets the name of the guest. This name will be displayed in the SDL 1091 window caption. The name will also be used for the VNC server. Also 1092 optionally set the top visible process name in Linux. Naming of 1093 individual threads can also be enabled on Linux to aid debugging. 1094ERST 1095 1096DEF("uuid", HAS_ARG, QEMU_OPTION_uuid, 1097 "-uuid %08x-%04x-%04x-%04x-%012x\n" 1098 " specify machine UUID\n", QEMU_ARCH_ALL) 1099SRST 1100``-uuid uuid`` 1101 Set system UUID. 1102ERST 1103 1104DEFHEADING() 1105 1106DEFHEADING(Block device options:) 1107 1108DEF("fda", HAS_ARG, QEMU_OPTION_fda, 1109 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL) 1110DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL) 1111SRST 1112``-fda file`` 1113 \ 1114``-fdb file`` 1115 Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in 1116 the System Emulation Users Guide). 1117ERST 1118 1119DEF("hda", HAS_ARG, QEMU_OPTION_hda, 1120 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL) 1121DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL) 1122DEF("hdc", HAS_ARG, QEMU_OPTION_hdc, 1123 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL) 1124DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL) 1125SRST 1126``-hda file`` 1127 \ 1128``-hdb file`` 1129 \ 1130``-hdc file`` 1131 \ 1132``-hdd file`` 1133 Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images` 1134 chapter in the System Emulation Users Guide). 1135ERST 1136 1137DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom, 1138 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n", 1139 QEMU_ARCH_ALL) 1140SRST 1141``-cdrom file`` 1142 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at 1143 the same time). You can use the host CD-ROM by using ``/dev/cdrom`` 1144 as filename. 1145ERST 1146 1147DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev, 1148 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n" 1149 " [,cache.direct=on|off][,cache.no-flush=on|off]\n" 1150 " [,read-only=on|off][,auto-read-only=on|off]\n" 1151 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n" 1152 " [,driver specific parameters...]\n" 1153 " configure a block backend\n", QEMU_ARCH_ALL) 1154SRST 1155``-blockdev option[,option[,option[,...]]]`` 1156 Define a new block driver node. Some of the options apply to all 1157 block drivers, other options are only accepted for a specific block 1158 driver. See below for a list of generic options and options for the 1159 most common block drivers. 1160 1161 Options that expect a reference to another node (e.g. ``file``) can 1162 be given in two ways. Either you specify the node name of an already 1163 existing node (file=node-name), or you define a new node inline, 1164 adding options for the referenced node after a dot 1165 (file.filename=path,file.aio=native). 1166 1167 A block driver node created with ``-blockdev`` can be used for a 1168 guest device by specifying its node name for the ``drive`` property 1169 in a ``-device`` argument that defines a block device. 1170 1171 ``Valid options for any block driver node:`` 1172 ``driver`` 1173 Specifies the block driver to use for the given node. 1174 1175 ``node-name`` 1176 This defines the name of the block driver node by which it 1177 will be referenced later. The name must be unique, i.e. it 1178 must not match the name of a different block driver node, or 1179 (if you use ``-drive`` as well) the ID of a drive. 1180 1181 If no node name is specified, it is automatically generated. 1182 The generated node name is not intended to be predictable 1183 and changes between QEMU invocations. For the top level, an 1184 explicit node name must be specified. 1185 1186 ``read-only`` 1187 Open the node read-only. Guest write attempts will fail. 1188 1189 Note that some block drivers support only read-only access, 1190 either generally or in certain configurations. In this case, 1191 the default value ``read-only=off`` does not work and the 1192 option must be specified explicitly. 1193 1194 ``auto-read-only`` 1195 If ``auto-read-only=on`` is set, QEMU may fall back to 1196 read-only usage even when ``read-only=off`` is requested, or 1197 even switch between modes as needed, e.g. depending on 1198 whether the image file is writable or whether a writing user 1199 is attached to the node. 1200 1201 ``force-share`` 1202 Override the image locking system of QEMU by forcing the 1203 node to utilize weaker shared access for permissions where 1204 it would normally request exclusive access. When there is 1205 the potential for multiple instances to have the same file 1206 open (whether this invocation of QEMU is the first or the 1207 second instance), both instances must permit shared access 1208 for the second instance to succeed at opening the file. 1209 1210 Enabling ``force-share=on`` requires ``read-only=on``. 1211 1212 ``cache.direct`` 1213 The host page cache can be avoided with ``cache.direct=on``. 1214 This will attempt to do disk IO directly to the guest's 1215 memory. QEMU may still perform an internal copy of the data. 1216 1217 ``cache.no-flush`` 1218 In case you don't care about data integrity over host 1219 failures, you can use ``cache.no-flush=on``. This option 1220 tells QEMU that it never needs to write any data to the disk 1221 but can instead keep things in cache. If anything goes 1222 wrong, like your host losing power, the disk storage getting 1223 disconnected accidentally, etc. your image will most 1224 probably be rendered unusable. 1225 1226 ``discard=discard`` 1227 discard is one of "ignore" (or "off") or "unmap" (or "on") 1228 and controls whether ``discard`` (also known as ``trim`` or 1229 ``unmap``) requests are ignored or passed to the filesystem. 1230 Some machine types may not support discard requests. 1231 1232 ``detect-zeroes=detect-zeroes`` 1233 detect-zeroes is "off", "on" or "unmap" and enables the 1234 automatic conversion of plain zero writes by the OS to 1235 driver specific optimized zero write commands. You may even 1236 choose "unmap" if discard is set to "unmap" to allow a zero 1237 write to be converted to an ``unmap`` operation. 1238 1239 ``Driver-specific options for file`` 1240 This is the protocol-level block driver for accessing regular 1241 files. 1242 1243 ``filename`` 1244 The path to the image file in the local filesystem 1245 1246 ``aio`` 1247 Specifies the AIO backend (threads/native/io_uring, 1248 default: threads) 1249 1250 ``locking`` 1251 Specifies whether the image file is protected with Linux OFD 1252 / POSIX locks. The default is to use the Linux Open File 1253 Descriptor API if available, otherwise no lock is applied. 1254 (auto/on/off, default: auto) 1255 1256 Example: 1257 1258 :: 1259 1260 -blockdev driver=file,node-name=disk,filename=disk.img 1261 1262 ``Driver-specific options for raw`` 1263 This is the image format block driver for raw images. It is 1264 usually stacked on top of a protocol level block driver such as 1265 ``file``. 1266 1267 ``file`` 1268 Reference to or definition of the data source block driver 1269 node (e.g. a ``file`` driver node) 1270 1271 Example 1: 1272 1273 :: 1274 1275 -blockdev driver=file,node-name=disk_file,filename=disk.img 1276 -blockdev driver=raw,node-name=disk,file=disk_file 1277 1278 Example 2: 1279 1280 :: 1281 1282 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img 1283 1284 ``Driver-specific options for qcow2`` 1285 This is the image format block driver for qcow2 images. It is 1286 usually stacked on top of a protocol level block driver such as 1287 ``file``. 1288 1289 ``file`` 1290 Reference to or definition of the data source block driver 1291 node (e.g. a ``file`` driver node) 1292 1293 ``backing`` 1294 Reference to or definition of the backing file block device 1295 (default is taken from the image file). It is allowed to 1296 pass ``null`` here in order to disable the default backing 1297 file. 1298 1299 ``lazy-refcounts`` 1300 Whether to enable the lazy refcounts feature (on/off; 1301 default is taken from the image file) 1302 1303 ``cache-size`` 1304 The maximum total size of the L2 table and refcount block 1305 caches in bytes (default: the sum of l2-cache-size and 1306 refcount-cache-size) 1307 1308 ``l2-cache-size`` 1309 The maximum size of the L2 table cache in bytes (default: if 1310 cache-size is not specified - 32M on Linux platforms, and 8M 1311 on non-Linux platforms; otherwise, as large as possible 1312 within the cache-size, while permitting the requested or the 1313 minimal refcount cache size) 1314 1315 ``refcount-cache-size`` 1316 The maximum size of the refcount block cache in bytes 1317 (default: 4 times the cluster size; or if cache-size is 1318 specified, the part of it which is not used for the L2 1319 cache) 1320 1321 ``cache-clean-interval`` 1322 Clean unused entries in the L2 and refcount caches. The 1323 interval is in seconds. The default value is 600 on 1324 supporting platforms, and 0 on other platforms. Setting it 1325 to 0 disables this feature. 1326 1327 ``pass-discard-request`` 1328 Whether discard requests to the qcow2 device should be 1329 forwarded to the data source (on/off; default: on if 1330 discard=unmap is specified, off otherwise) 1331 1332 ``pass-discard-snapshot`` 1333 Whether discard requests for the data source should be 1334 issued when a snapshot operation (e.g. deleting a snapshot) 1335 frees clusters in the qcow2 file (on/off; default: on) 1336 1337 ``pass-discard-other`` 1338 Whether discard requests for the data source should be 1339 issued on other occasions where a cluster gets freed 1340 (on/off; default: off) 1341 1342 ``overlap-check`` 1343 Which overlap checks to perform for writes to the image 1344 (none/constant/cached/all; default: cached). For details or 1345 finer granularity control refer to the QAPI documentation of 1346 ``blockdev-add``. 1347 1348 Example 1: 1349 1350 :: 1351 1352 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2 1353 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216 1354 1355 Example 2: 1356 1357 :: 1358 1359 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2 1360 1361 ``Driver-specific options for other drivers`` 1362 Please refer to the QAPI documentation of the ``blockdev-add`` 1363 QMP command. 1364ERST 1365 1366DEF("drive", HAS_ARG, QEMU_OPTION_drive, 1367 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" 1368 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" 1369 " [,snapshot=on|off][,rerror=ignore|stop|report]\n" 1370 " [,werror=ignore|stop|report|enospc][,id=name]\n" 1371 " [,aio=threads|native|io_uring]\n" 1372 " [,readonly=on|off][,copy-on-read=on|off]\n" 1373 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n" 1374 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n" 1375 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n" 1376 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n" 1377 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n" 1378 " [[,iops_size=is]]\n" 1379 " [[,group=g]]\n" 1380 " use 'file' as a drive image\n", QEMU_ARCH_ALL) 1381SRST 1382``-drive option[,option[,option[,...]]]`` 1383 Define a new drive. This includes creating a block driver node (the 1384 backend) as well as a guest device, and is mostly a shortcut for 1385 defining the corresponding ``-blockdev`` and ``-device`` options. 1386 1387 ``-drive`` accepts all options that are accepted by ``-blockdev``. 1388 In addition, it knows the following options: 1389 1390 ``file=file`` 1391 This option defines which disk image (see the :ref:`disk images` 1392 chapter in the System Emulation Users Guide) to use with this drive. 1393 If the filename contains comma, you must double it (for instance, 1394 "file=my,,file" to use file "my,file"). 1395 1396 Special files such as iSCSI devices can be specified using 1397 protocol specific URLs. See the section for "Device URL Syntax" 1398 for more information. 1399 1400 ``if=interface`` 1401 This option defines on which type on interface the drive is 1402 connected. Available types are: ide, scsi, sd, mtd, floppy, 1403 pflash, virtio, none. 1404 1405 ``bus=bus,unit=unit`` 1406 These options define where is connected the drive by defining 1407 the bus number and the unit id. 1408 1409 ``index=index`` 1410 This option defines where the drive is connected by using an 1411 index in the list of available connectors of a given interface 1412 type. 1413 1414 ``media=media`` 1415 This option defines the type of the media: disk or cdrom. 1416 1417 ``snapshot=snapshot`` 1418 snapshot is "on" or "off" and controls snapshot mode for the 1419 given drive (see ``-snapshot``). 1420 1421 ``cache=cache`` 1422 cache is "none", "writeback", "unsafe", "directsync" or 1423 "writethrough" and controls how the host cache is used to access 1424 block data. This is a shortcut that sets the ``cache.direct`` 1425 and ``cache.no-flush`` options (as in ``-blockdev``), and 1426 additionally ``cache.writeback``, which provides a default for 1427 the ``write-cache`` option of block guest devices (as in 1428 ``-device``). The modes correspond to the following settings: 1429 1430 ============= =============== ============ ============== 1431 \ cache.writeback cache.direct cache.no-flush 1432 ============= =============== ============ ============== 1433 writeback on off off 1434 none on on off 1435 writethrough off off off 1436 directsync off on off 1437 unsafe on off on 1438 ============= =============== ============ ============== 1439 1440 The default mode is ``cache=writeback``. 1441 1442 ``aio=aio`` 1443 aio is "threads", "native", or "io_uring" and selects between pthread 1444 based disk I/O, native Linux AIO, or Linux io_uring API. 1445 1446 ``format=format`` 1447 Specify which disk format will be used rather than detecting the 1448 format. Can be used to specify format=raw to avoid interpreting 1449 an untrusted format header. 1450 1451 ``werror=action,rerror=action`` 1452 Specify which action to take on write and read errors. Valid 1453 actions are: "ignore" (ignore the error and try to continue), 1454 "stop" (pause QEMU), "report" (report the error to the guest), 1455 "enospc" (pause QEMU only if the host disk is full; report the 1456 error to the guest otherwise). The default setting is 1457 ``werror=enospc`` and ``rerror=report``. 1458 1459 ``copy-on-read=copy-on-read`` 1460 copy-on-read is "on" or "off" and enables whether to copy read 1461 backing file sectors into the image file. 1462 1463 ``bps=b,bps_rd=r,bps_wr=w`` 1464 Specify bandwidth throttling limits in bytes per second, either 1465 for all request types or for reads or writes only. Small values 1466 can lead to timeouts or hangs inside the guest. A safe minimum 1467 for disks is 2 MB/s. 1468 1469 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm`` 1470 Specify bursts in bytes per second, either for all request types 1471 or for reads or writes only. Bursts allow the guest I/O to spike 1472 above the limit temporarily. 1473 1474 ``iops=i,iops_rd=r,iops_wr=w`` 1475 Specify request rate limits in requests per second, either for 1476 all request types or for reads or writes only. 1477 1478 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm`` 1479 Specify bursts in requests per second, either for all request 1480 types or for reads or writes only. Bursts allow the guest I/O to 1481 spike above the limit temporarily. 1482 1483 ``iops_size=is`` 1484 Let every is bytes of a request count as a new request for iops 1485 throttling purposes. Use this option to prevent guests from 1486 circumventing iops limits by sending fewer but larger requests. 1487 1488 ``group=g`` 1489 Join a throttling quota group with given name g. All drives that 1490 are members of the same group are accounted for together. Use 1491 this option to prevent guests from circumventing throttling 1492 limits by using many small disks instead of a single larger 1493 disk. 1494 1495 By default, the ``cache.writeback=on`` mode is used. It will report 1496 data writes as completed as soon as the data is present in the host 1497 page cache. This is safe as long as your guest OS makes sure to 1498 correctly flush disk caches where needed. If your guest OS does not 1499 handle volatile disk write caches correctly and your host crashes or 1500 loses power, then the guest may experience data corruption. 1501 1502 For such guests, you should consider using ``cache.writeback=off``. 1503 This means that the host page cache will be used to read and write 1504 data, but write notification will be sent to the guest only after 1505 QEMU has made sure to flush each write to the disk. Be aware that 1506 this has a major impact on performance. 1507 1508 When using the ``-snapshot`` option, unsafe caching is always used. 1509 1510 Copy-on-read avoids accessing the same backing file sectors 1511 repeatedly and is useful when the backing file is over a slow 1512 network. By default copy-on-read is off. 1513 1514 Instead of ``-cdrom`` you can use: 1515 1516 .. parsed-literal:: 1517 1518 |qemu_system| -drive file=file,index=2,media=cdrom 1519 1520 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use: 1521 1522 .. parsed-literal:: 1523 1524 |qemu_system| -drive file=file,index=0,media=disk 1525 |qemu_system| -drive file=file,index=1,media=disk 1526 |qemu_system| -drive file=file,index=2,media=disk 1527 |qemu_system| -drive file=file,index=3,media=disk 1528 1529 You can open an image using pre-opened file descriptors from an fd 1530 set: 1531 1532 .. parsed-literal:: 1533 1534 |qemu_system| \\ 1535 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 1536 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 1537 -drive file=/dev/fdset/2,index=0,media=disk 1538 1539 You can connect a CDROM to the slave of ide0: 1540 1541 .. parsed-literal:: 1542 1543 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom 1544 1545 If you don't specify the "file=" argument, you define an empty 1546 drive: 1547 1548 .. parsed-literal:: 1549 1550 |qemu_system_x86| -drive if=ide,index=1,media=cdrom 1551 1552 Instead of ``-fda``, ``-fdb``, you can use: 1553 1554 .. parsed-literal:: 1555 1556 |qemu_system_x86| -drive file=file,index=0,if=floppy 1557 |qemu_system_x86| -drive file=file,index=1,if=floppy 1558 1559 By default, interface is "ide" and index is automatically 1560 incremented: 1561 1562 .. parsed-literal:: 1563 1564 |qemu_system_x86| -drive file=a -drive file=b" 1565 1566 is interpreted like: 1567 1568 .. parsed-literal:: 1569 1570 |qemu_system_x86| -hda a -hdb b 1571ERST 1572 1573DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock, 1574 "-mtdblock file use 'file' as on-board Flash memory image\n", 1575 QEMU_ARCH_ALL) 1576SRST 1577``-mtdblock file`` 1578 Use file as on-board Flash memory image. 1579ERST 1580 1581DEF("sd", HAS_ARG, QEMU_OPTION_sd, 1582 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL) 1583SRST 1584``-sd file`` 1585 Use file as SecureDigital card image. 1586ERST 1587 1588DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, 1589 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) 1590SRST 1591``-pflash file`` 1592 Use file as a parallel flash image. 1593ERST 1594 1595DEF("snapshot", 0, QEMU_OPTION_snapshot, 1596 "-snapshot write to temporary files instead of disk image files\n", 1597 QEMU_ARCH_ALL) 1598SRST 1599``-snapshot`` 1600 Write to temporary files instead of disk image files. In this case, 1601 the raw disk image you use is not written back. You can however 1602 force the write back by pressing C-a s (see the :ref:`disk images` 1603 chapter in the System Emulation Users Guide). 1604ERST 1605 1606DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev, 1607 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1608 " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n" 1609 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n" 1610 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n" 1611 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n" 1612 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n" 1613 " [[,throttling.iops-size=is]]\n" 1614 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n" 1615 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n" 1616 "-fsdev synth,id=id\n", 1617 QEMU_ARCH_ALL) 1618 1619SRST 1620``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]`` 1621 \ 1622``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]`` 1623 \ 1624``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]`` 1625 \ 1626``-fsdev synth,id=id[,readonly=on]`` 1627 Define a new file system device. Valid options are: 1628 1629 ``local`` 1630 Accesses to the filesystem are done by QEMU. 1631 1632 ``proxy`` 1633 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1634 1635 ``synth`` 1636 Synthetic filesystem, only used by QTests. 1637 1638 ``id=id`` 1639 Specifies identifier for this device. 1640 1641 ``path=path`` 1642 Specifies the export path for the file system device. Files 1643 under this path will be available to the 9p client on the guest. 1644 1645 ``security_model=security_model`` 1646 Specifies the security model to be used for this export path. 1647 Supported security models are "passthrough", "mapped-xattr", 1648 "mapped-file" and "none". In "passthrough" security model, files 1649 are stored using the same credentials as they are created on the 1650 guest. This requires QEMU to run as root. In "mapped-xattr" 1651 security model, some of the file attributes like uid, gid, mode 1652 bits and link target are stored as file attributes. For 1653 "mapped-file" these attributes are stored in the hidden 1654 .virtfs\_metadata directory. Directories exported by this 1655 security model cannot interact with other unix tools. "none" 1656 security model is same as passthrough except the sever won't 1657 report failures if it fails to set file attributes like 1658 ownership. Security model is mandatory only for local fsdriver. 1659 Other fsdrivers (like proxy) don't take security model as a 1660 parameter. 1661 1662 ``writeout=writeout`` 1663 This is an optional argument. The only supported value is 1664 "immediate". This means that host page cache will be used to 1665 read and write data but write notification will be sent to the 1666 guest only when the data has been reported as written by the 1667 storage subsystem. 1668 1669 ``readonly=on`` 1670 Enables exporting 9p share as a readonly mount for guests. By 1671 default read-write access is given. 1672 1673 ``socket=socket`` 1674 Enables proxy filesystem driver to use passed socket file for 1675 communicating with virtfs-proxy-helper(1). 1676 1677 ``sock_fd=sock_fd`` 1678 Enables proxy filesystem driver to use passed socket descriptor 1679 for communicating with virtfs-proxy-helper(1). Usually a helper 1680 like libvirt will create socketpair and pass one of the fds as 1681 sock\_fd. 1682 1683 ``fmode=fmode`` 1684 Specifies the default mode for newly created files on the host. 1685 Works only with security models "mapped-xattr" and 1686 "mapped-file". 1687 1688 ``dmode=dmode`` 1689 Specifies the default mode for newly created directories on the 1690 host. Works only with security models "mapped-xattr" and 1691 "mapped-file". 1692 1693 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w`` 1694 Specify bandwidth throttling limits in bytes per second, either 1695 for all request types or for reads or writes only. 1696 1697 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm`` 1698 Specify bursts in bytes per second, either for all request types 1699 or for reads or writes only. Bursts allow the guest I/O to spike 1700 above the limit temporarily. 1701 1702 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w`` 1703 Specify request rate limits in requests per second, either for 1704 all request types or for reads or writes only. 1705 1706 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm`` 1707 Specify bursts in requests per second, either for all request 1708 types or for reads or writes only. Bursts allow the guest I/O to 1709 spike above the limit temporarily. 1710 1711 ``throttling.iops-size=is`` 1712 Let every is bytes of a request count as a new request for iops 1713 throttling purposes. 1714 1715 -fsdev option is used along with -device driver "virtio-9p-...". 1716 1717``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag`` 1718 Options for virtio-9p-... driver are: 1719 1720 ``type`` 1721 Specifies the variant to be used. Supported values are "pci", 1722 "ccw" or "device", depending on the machine type. 1723 1724 ``fsdev=id`` 1725 Specifies the id value specified along with -fsdev option. 1726 1727 ``mount_tag=mount_tag`` 1728 Specifies the tag name to be used by the guest to mount this 1729 export point. 1730ERST 1731 1732DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, 1733 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1734 " [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n" 1735 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n" 1736 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n" 1737 "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n", 1738 QEMU_ARCH_ALL) 1739 1740SRST 1741``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]`` 1742 \ 1743``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1744 \ 1745``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1746 \ 1747``-virtfs synth,mount_tag=mount_tag`` 1748 Define a new virtual filesystem device and expose it to the guest using 1749 a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain 1750 directory on host is made directly accessible by guest as a pass-through 1751 file system by using the 9P network protocol for communication between 1752 host and guests, if desired even accessible, shared by several guests 1753 simultaniously. 1754 1755 Note that ``-virtfs`` is actually just a convenience shortcut for its 1756 generalized form ``-fsdev -device virtio-9p-pci``. 1757 1758 The general form of pass-through file system options are: 1759 1760 ``local`` 1761 Accesses to the filesystem are done by QEMU. 1762 1763 ``proxy`` 1764 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1765 1766 ``synth`` 1767 Synthetic filesystem, only used by QTests. 1768 1769 ``id=id`` 1770 Specifies identifier for the filesystem device 1771 1772 ``path=path`` 1773 Specifies the export path for the file system device. Files 1774 under this path will be available to the 9p client on the guest. 1775 1776 ``security_model=security_model`` 1777 Specifies the security model to be used for this export path. 1778 Supported security models are "passthrough", "mapped-xattr", 1779 "mapped-file" and "none". In "passthrough" security model, files 1780 are stored using the same credentials as they are created on the 1781 guest. This requires QEMU to run as root. In "mapped-xattr" 1782 security model, some of the file attributes like uid, gid, mode 1783 bits and link target are stored as file attributes. For 1784 "mapped-file" these attributes are stored in the hidden 1785 .virtfs\_metadata directory. Directories exported by this 1786 security model cannot interact with other unix tools. "none" 1787 security model is same as passthrough except the sever won't 1788 report failures if it fails to set file attributes like 1789 ownership. Security model is mandatory only for local fsdriver. 1790 Other fsdrivers (like proxy) don't take security model as a 1791 parameter. 1792 1793 ``writeout=writeout`` 1794 This is an optional argument. The only supported value is 1795 "immediate". This means that host page cache will be used to 1796 read and write data but write notification will be sent to the 1797 guest only when the data has been reported as written by the 1798 storage subsystem. 1799 1800 ``readonly=on`` 1801 Enables exporting 9p share as a readonly mount for guests. By 1802 default read-write access is given. 1803 1804 ``socket=socket`` 1805 Enables proxy filesystem driver to use passed socket file for 1806 communicating with virtfs-proxy-helper(1). Usually a helper like 1807 libvirt will create socketpair and pass one of the fds as 1808 sock\_fd. 1809 1810 ``sock_fd`` 1811 Enables proxy filesystem driver to use passed 'sock\_fd' as the 1812 socket descriptor for interfacing with virtfs-proxy-helper(1). 1813 1814 ``fmode=fmode`` 1815 Specifies the default mode for newly created files on the host. 1816 Works only with security models "mapped-xattr" and 1817 "mapped-file". 1818 1819 ``dmode=dmode`` 1820 Specifies the default mode for newly created directories on the 1821 host. Works only with security models "mapped-xattr" and 1822 "mapped-file". 1823 1824 ``mount_tag=mount_tag`` 1825 Specifies the tag name to be used by the guest to mount this 1826 export point. 1827 1828 ``multidevs=multidevs`` 1829 Specifies how to deal with multiple devices being shared with a 1830 9p export. Supported behaviours are either "remap", "forbid" or 1831 "warn". The latter is the default behaviour on which virtfs 9p 1832 expects only one device to be shared with the same export, and 1833 if more than one device is shared and accessed via the same 9p 1834 export then only a warning message is logged (once) by qemu on 1835 host side. In order to avoid file ID collisions on guest you 1836 should either create a separate virtfs export for each device to 1837 be shared with guests (recommended way) or you might use "remap" 1838 instead which allows you to share multiple devices with only one 1839 export instead, which is achieved by remapping the original 1840 inode numbers from host to guest in a way that would prevent 1841 such collisions. Remapping inodes in such use cases is required 1842 because the original device IDs from host are never passed and 1843 exposed on guest. Instead all files of an export shared with 1844 virtfs always share the same device id on guest. So two files 1845 with identical inode numbers but from actually different devices 1846 on host would otherwise cause a file ID collision and hence 1847 potential misbehaviours on guest. "forbid" on the other hand 1848 assumes like "warn" that only one device is shared by the same 1849 export, however it will not only log a warning message but also 1850 deny access to additional devices on guest. Note though that 1851 "forbid" does currently not block all possible file access 1852 operations (e.g. readdir() would still return entries from other 1853 devices). 1854ERST 1855 1856DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi, 1857 "-iscsi [user=user][,password=password]\n" 1858 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n" 1859 " [,initiator-name=initiator-iqn][,id=target-iqn]\n" 1860 " [,timeout=timeout]\n" 1861 " iSCSI session parameters\n", QEMU_ARCH_ALL) 1862 1863SRST 1864``-iscsi`` 1865 Configure iSCSI session parameters. 1866ERST 1867 1868DEFHEADING() 1869 1870DEFHEADING(USB convenience options:) 1871 1872DEF("usb", 0, QEMU_OPTION_usb, 1873 "-usb enable on-board USB host controller (if not enabled by default)\n", 1874 QEMU_ARCH_ALL) 1875SRST 1876``-usb`` 1877 Enable USB emulation on machine types with an on-board USB host 1878 controller (if not enabled by default). Note that on-board USB host 1879 controllers may not support USB 3.0. In this case 1880 ``-device qemu-xhci`` can be used instead on machines with PCI. 1881ERST 1882 1883DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice, 1884 "-usbdevice name add the host or guest USB device 'name'\n", 1885 QEMU_ARCH_ALL) 1886SRST 1887``-usbdevice devname`` 1888 Add the USB device devname, and enable an on-board USB controller 1889 if possible and necessary (just like it can be done via 1890 ``-machine usb=on``). Note that this option is mainly intended for 1891 the user's convenience only. More fine-grained control can be 1892 achieved by selecting a USB host controller (if necessary) and the 1893 desired USB device via the ``-device`` option instead. For example, 1894 instead of using ``-usbdevice mouse`` it is possible to use 1895 ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse 1896 to a USB 3.0 controller instead (at least on machines that support 1897 PCI and do not have an USB controller enabled by default yet). 1898 For more details, see the chapter about 1899 :ref:`Connecting USB devices` in the System Emulation Users Guide. 1900 Possible devices for devname are: 1901 1902 ``braille`` 1903 Braille device. This will use BrlAPI to display the braille 1904 output on a real or fake device (i.e. it also creates a 1905 corresponding ``braille`` chardev automatically beside the 1906 ``usb-braille`` USB device). 1907 1908 ``keyboard`` 1909 Standard USB keyboard. Will override the PS/2 keyboard (if present). 1910 1911 ``mouse`` 1912 Virtual Mouse. This will override the PS/2 mouse emulation when 1913 activated. 1914 1915 ``tablet`` 1916 Pointer device that uses absolute coordinates (like a 1917 touchscreen). This means QEMU is able to report the mouse 1918 position without having to grab the mouse. Also overrides the 1919 PS/2 mouse emulation when activated. 1920 1921 ``wacom-tablet`` 1922 Wacom PenPartner USB tablet. 1923 1924 1925ERST 1926 1927DEFHEADING() 1928 1929DEFHEADING(Display options:) 1930 1931DEF("display", HAS_ARG, QEMU_OPTION_display, 1932#if defined(CONFIG_SPICE) 1933 "-display spice-app[,gl=on|off]\n" 1934#endif 1935#if defined(CONFIG_SDL) 1936 "-display sdl[,gl=on|core|es|off][,grab-mod=<mod>][,show-cursor=on|off]\n" 1937 " [,window-close=on|off]\n" 1938#endif 1939#if defined(CONFIG_GTK) 1940 "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n" 1941 " [,show-tabs=on|off][,show-cursor=on|off][,window-close=on|off]\n" 1942#endif 1943#if defined(CONFIG_VNC) 1944 "-display vnc=<display>[,<optargs>]\n" 1945#endif 1946#if defined(CONFIG_CURSES) 1947 "-display curses[,charset=<encoding>]\n" 1948#endif 1949#if defined(CONFIG_COCOA) 1950 "-display cocoa[,full-grab=on|off][,swap-opt-cmd=on|off]\n" 1951#endif 1952#if defined(CONFIG_OPENGL) 1953 "-display egl-headless[,rendernode=<file>]\n" 1954#endif 1955#if defined(CONFIG_DBUS_DISPLAY) 1956 "-display dbus[,addr=<dbusaddr>]\n" 1957 " [,gl=on|core|es|off][,rendernode=<file>]\n" 1958#endif 1959#if defined(CONFIG_COCOA) 1960 "-display cocoa[,show-cursor=on|off][,left-command-key=on|off]\n" 1961#endif 1962 "-display none\n" 1963 " select display backend type\n" 1964 " The default display is equivalent to\n " 1965#if defined(CONFIG_GTK) 1966 "\"-display gtk\"\n" 1967#elif defined(CONFIG_SDL) 1968 "\"-display sdl\"\n" 1969#elif defined(CONFIG_COCOA) 1970 "\"-display cocoa\"\n" 1971#elif defined(CONFIG_VNC) 1972 "\"-vnc localhost:0,to=99,id=default\"\n" 1973#else 1974 "\"-display none\"\n" 1975#endif 1976 , QEMU_ARCH_ALL) 1977SRST 1978``-display type`` 1979 Select type of display to use. Use ``-display help`` to list the available 1980 display types. Valid values for type are 1981 1982 ``spice-app[,gl=on|off]`` 1983 Start QEMU as a Spice server and launch the default Spice client 1984 application. The Spice server will redirect the serial consoles 1985 and QEMU monitors. (Since 4.0) 1986 1987 ``dbus`` 1988 Export the display over D-Bus interfaces. (Since 7.0) 1989 1990 The connection is registered with the "org.qemu" name (and queued when 1991 already owned). 1992 1993 ``addr=<dbusaddr>`` : D-Bus bus address to connect to. 1994 1995 ``p2p=yes|no`` : Use peer-to-peer connection, accepted via QMP ``add_client``. 1996 1997 ``gl=on|off|core|es`` : Use OpenGL for rendering (the D-Bus interface 1998 will share framebuffers with DMABUF file descriptors). 1999 2000 ``sdl`` 2001 Display video output via SDL (usually in a separate graphics 2002 window; see the SDL documentation for other possibilities). 2003 Valid parameters are: 2004 2005 ``grab-mod=<mods>`` : Used to select the modifier keys for toggling 2006 the mouse grabbing in conjunction with the "g" key. ``<mods>`` can be 2007 either ``lshift-lctrl-lalt`` or ``rctrl``. 2008 2009 ``gl=on|off|core|es`` : Use OpenGL for displaying 2010 2011 ``show-cursor=on|off`` : Force showing the mouse cursor 2012 2013 ``window-close=on|off`` : Allow to quit qemu with window close button 2014 2015 ``gtk`` 2016 Display video output in a GTK window. This interface provides 2017 drop-down menus and other UI elements to configure and control 2018 the VM during runtime. Valid parameters are: 2019 2020 ``full-screen=on|off`` : Start in fullscreen mode 2021 2022 ``gl=on|off`` : Use OpenGL for displaying 2023 2024 ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover 2025 2026 ``show-tabs=on|off`` : Display the tab bar for switching between the 2027 various graphical interfaces (e.g. VGA and 2028 virtual console character devices) by default. 2029 2030 ``show-cursor=on|off`` : Force showing the mouse cursor 2031 2032 ``window-close=on|off`` : Allow to quit qemu with window close button 2033 2034 ``curses[,charset=<encoding>]`` 2035 Display video output via curses. For graphics device models 2036 which support a text mode, QEMU can display this output using a 2037 curses/ncurses interface. Nothing is displayed when the graphics 2038 device is in graphical mode or if the graphics device does not 2039 support a text mode. Generally only the VGA device models 2040 support text mode. The font charset used by the guest can be 2041 specified with the ``charset`` option, for example 2042 ``charset=CP850`` for IBM CP850 encoding. The default is 2043 ``CP437``. 2044 2045 ``cocoa`` 2046 Display video output in a Cocoa window. Mac only. This interface 2047 provides drop-down menus and other UI elements to configure and 2048 control the VM during runtime. Valid parameters are: 2049 2050 ``show-cursor=on|off`` : Force showing the mouse cursor 2051 2052 ``left-command-key=on|off`` : Disable forwarding left command key to host 2053 2054 ``egl-headless[,rendernode=<file>]`` 2055 Offload all OpenGL operations to a local DRI device. For any 2056 graphical display, this display needs to be paired with either 2057 VNC or SPICE displays. 2058 2059 ``vnc=<display>`` 2060 Start a VNC server on display <display> 2061 2062 ``none`` 2063 Do not display video output. The guest will still see an 2064 emulated graphics card, but its output will not be displayed to 2065 the QEMU user. This option differs from the -nographic option in 2066 that it only affects what is done with video output; -nographic 2067 also changes the destination of the serial and parallel port 2068 data. 2069ERST 2070 2071DEF("nographic", 0, QEMU_OPTION_nographic, 2072 "-nographic disable graphical output and redirect serial I/Os to console\n", 2073 QEMU_ARCH_ALL) 2074SRST 2075``-nographic`` 2076 Normally, if QEMU is compiled with graphical window support, it 2077 displays output such as guest graphics, guest console, and the QEMU 2078 monitor in a window. With this option, you can totally disable 2079 graphical output so that QEMU is a simple command line application. 2080 The emulated serial port is redirected on the console and muxed with 2081 the monitor (unless redirected elsewhere explicitly). Therefore, you 2082 can still use QEMU to debug a Linux kernel with a serial console. 2083 Use C-a h for help on switching between the console and monitor. 2084ERST 2085 2086#ifdef CONFIG_SPICE 2087DEF("spice", HAS_ARG, QEMU_OPTION_spice, 2088 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n" 2089 " [,x509-key-file=<file>][,x509-key-password=<file>]\n" 2090 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n" 2091 " [,x509-dh-key-file=<file>][,addr=addr]\n" 2092 " [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n" 2093 " [,tls-ciphers=<list>]\n" 2094 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n" 2095 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n" 2096 " [,sasl=on|off][,disable-ticketing=on|off]\n" 2097 " [,password=<string>][,password-secret=<secret-id>]\n" 2098 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n" 2099 " [,jpeg-wan-compression=[auto|never|always]]\n" 2100 " [,zlib-glz-wan-compression=[auto|never|always]]\n" 2101 " [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n" 2102 " [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n" 2103 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n" 2104 " [,gl=[on|off]][,rendernode=<file>]\n" 2105 " enable spice\n" 2106 " at least one of {port, tls-port} is mandatory\n", 2107 QEMU_ARCH_ALL) 2108#endif 2109SRST 2110``-spice option[,option[,...]]`` 2111 Enable the spice remote desktop protocol. Valid options are 2112 2113 ``port=<nr>`` 2114 Set the TCP port spice is listening on for plaintext channels. 2115 2116 ``addr=<addr>`` 2117 Set the IP address spice is listening on. Default is any 2118 address. 2119 2120 ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off`` 2121 Force using the specified IP version. 2122 2123 ``password=<string>`` 2124 Set the password you need to authenticate. 2125 2126 This option is deprecated and insecure because it leaves the 2127 password visible in the process listing. Use ``password-secret`` 2128 instead. 2129 2130 ``password-secret=<secret-id>`` 2131 Set the ID of the ``secret`` object containing the password 2132 you need to authenticate. 2133 2134 ``sasl=on|off`` 2135 Require that the client use SASL to authenticate with the spice. 2136 The exact choice of authentication method used is controlled 2137 from the system / user's SASL configuration file for the 'qemu' 2138 service. This is typically found in /etc/sasl2/qemu.conf. If 2139 running QEMU as an unprivileged user, an environment variable 2140 SASL\_CONF\_PATH can be used to make it search alternate 2141 locations for the service config. While some SASL auth methods 2142 can also provide data encryption (eg GSSAPI), it is recommended 2143 that SASL always be combined with the 'tls' and 'x509' settings 2144 to enable use of SSL and server certificates. This ensures a 2145 data encryption preventing compromise of authentication 2146 credentials. 2147 2148 ``disable-ticketing=on|off`` 2149 Allow client connects without authentication. 2150 2151 ``disable-copy-paste=on|off`` 2152 Disable copy paste between the client and the guest. 2153 2154 ``disable-agent-file-xfer=on|off`` 2155 Disable spice-vdagent based file-xfer between the client and the 2156 guest. 2157 2158 ``tls-port=<nr>`` 2159 Set the TCP port spice is listening on for encrypted channels. 2160 2161 ``x509-dir=<dir>`` 2162 Set the x509 file directory. Expects same filenames as -vnc 2163 $display,x509=$dir 2164 2165 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>`` 2166 The x509 file names can also be configured individually. 2167 2168 ``tls-ciphers=<list>`` 2169 Specify which ciphers to use. 2170 2171 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]`` 2172 Force specific channel to be used with or without TLS 2173 encryption. The options can be specified multiple times to 2174 configure multiple channels. The special name "default" can be 2175 used to set the default mode. For channels which are not 2176 explicitly forced into one mode the spice client is allowed to 2177 pick tls/plaintext as he pleases. 2178 2179 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]`` 2180 Configure image compression (lossless). Default is auto\_glz. 2181 2182 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]`` 2183 Configure wan image compression (lossy for slow links). Default 2184 is auto. 2185 2186 ``streaming-video=[off|all|filter]`` 2187 Configure video stream detection. Default is off. 2188 2189 ``agent-mouse=[on|off]`` 2190 Enable/disable passing mouse events via vdagent. Default is on. 2191 2192 ``playback-compression=[on|off]`` 2193 Enable/disable audio stream compression (using celt 0.5.1). 2194 Default is on. 2195 2196 ``seamless-migration=[on|off]`` 2197 Enable/disable spice seamless migration. Default is off. 2198 2199 ``gl=[on|off]`` 2200 Enable/disable OpenGL context. Default is off. 2201 2202 ``rendernode=<file>`` 2203 DRM render node for OpenGL rendering. If not specified, it will 2204 pick the first available. (Since 2.9) 2205ERST 2206 2207DEF("portrait", 0, QEMU_OPTION_portrait, 2208 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n", 2209 QEMU_ARCH_ALL) 2210SRST 2211``-portrait`` 2212 Rotate graphical output 90 deg left (only PXA LCD). 2213ERST 2214 2215DEF("rotate", HAS_ARG, QEMU_OPTION_rotate, 2216 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n", 2217 QEMU_ARCH_ALL) 2218SRST 2219``-rotate deg`` 2220 Rotate graphical output some deg left (only PXA LCD). 2221ERST 2222 2223DEF("vga", HAS_ARG, QEMU_OPTION_vga, 2224 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n" 2225 " select video card type\n", QEMU_ARCH_ALL) 2226SRST 2227``-vga type`` 2228 Select type of VGA card to emulate. Valid values for type are 2229 2230 ``cirrus`` 2231 Cirrus Logic GD5446 Video card. All Windows versions starting 2232 from Windows 95 should recognize and use this graphic card. For 2233 optimal performances, use 16 bit color depth in the guest and 2234 the host OS. (This card was the default before QEMU 2.2) 2235 2236 ``std`` 2237 Standard VGA card with Bochs VBE extensions. If your guest OS 2238 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if 2239 you want to use high resolution modes (>= 1280x1024x16) then you 2240 should use this option. (This card is the default since QEMU 2241 2.2) 2242 2243 ``vmware`` 2244 VMWare SVGA-II compatible adapter. Use it if you have 2245 sufficiently recent XFree86/XOrg server or Windows guest with a 2246 driver for this card. 2247 2248 ``qxl`` 2249 QXL paravirtual graphic card. It is VGA compatible (including 2250 VESA 2.0 VBE support). Works best with qxl guest drivers 2251 installed though. Recommended choice when using the spice 2252 protocol. 2253 2254 ``tcx`` 2255 (sun4m only) Sun TCX framebuffer. This is the default 2256 framebuffer for sun4m machines and offers both 8-bit and 24-bit 2257 colour depths at a fixed resolution of 1024x768. 2258 2259 ``cg3`` 2260 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit 2261 framebuffer for sun4m machines available in both 1024x768 2262 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people 2263 wishing to run older Solaris versions. 2264 2265 ``virtio`` 2266 Virtio VGA card. 2267 2268 ``none`` 2269 Disable VGA card. 2270ERST 2271 2272DEF("full-screen", 0, QEMU_OPTION_full_screen, 2273 "-full-screen start in full screen\n", QEMU_ARCH_ALL) 2274SRST 2275``-full-screen`` 2276 Start in full screen. 2277ERST 2278 2279DEF("g", HAS_ARG, QEMU_OPTION_g , 2280 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n", 2281 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K) 2282SRST 2283``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]`` 2284 Set the initial graphical resolution and depth (PPC, SPARC only). 2285 2286 For PPC the default is 800x600x32. 2287 2288 For SPARC with the TCX graphics device, the default is 1024x768x8 2289 with the option of 1024x768x24. For cgthree, the default is 2290 1024x768x8 with the option of 1152x900x8 for people who wish to use 2291 OBP. 2292ERST 2293 2294DEF("vnc", HAS_ARG, QEMU_OPTION_vnc , 2295 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL) 2296SRST 2297``-vnc display[,option[,option[,...]]]`` 2298 Normally, if QEMU is compiled with graphical window support, it 2299 displays output such as guest graphics, guest console, and the QEMU 2300 monitor in a window. With this option, you can have QEMU listen on 2301 VNC display display and redirect the VGA display over the VNC 2302 session. It is very useful to enable the usb tablet device when 2303 using this option (option ``-device usb-tablet``). When using the 2304 VNC display, you must use the ``-k`` parameter to set the keyboard 2305 layout if you are not using en-us. Valid syntax for the display is 2306 2307 ``to=L`` 2308 With this option, QEMU will try next available VNC displays, 2309 until the number L, if the origianlly defined "-vnc display" is 2310 not available, e.g. port 5900+display is already used by another 2311 application. By default, to=0. 2312 2313 ``host:d`` 2314 TCP connections will only be allowed from host on display d. By 2315 convention the TCP port is 5900+d. Optionally, host can be 2316 omitted in which case the server will accept connections from 2317 any host. 2318 2319 ``unix:path`` 2320 Connections will be allowed over UNIX domain sockets where path 2321 is the location of a unix socket to listen for connections on. 2322 2323 ``none`` 2324 VNC is initialized but not started. The monitor ``change`` 2325 command can be used to later start the VNC server. 2326 2327 Following the display value there may be one or more option flags 2328 separated by commas. Valid options are 2329 2330 ``reverse=on|off`` 2331 Connect to a listening VNC client via a "reverse" connection. 2332 The client is specified by the display. For reverse network 2333 connections (host:d,``reverse``), the d argument is a TCP port 2334 number, not a display number. 2335 2336 ``websocket=on|off`` 2337 Opens an additional TCP listening port dedicated to VNC 2338 Websocket connections. If a bare websocket option is given, the 2339 Websocket port is 5700+display. An alternative port can be 2340 specified with the syntax ``websocket``\ =port. 2341 2342 If host is specified connections will only be allowed from this 2343 host. It is possible to control the websocket listen address 2344 independently, using the syntax ``websocket``\ =host:port. 2345 2346 If no TLS credentials are provided, the websocket connection 2347 runs in unencrypted mode. If TLS credentials are provided, the 2348 websocket connection requires encrypted client connections. 2349 2350 ``password=on|off`` 2351 Require that password based authentication is used for client 2352 connections. 2353 2354 The password must be set separately using the ``set_password`` 2355 command in the :ref:`QEMU monitor`. The 2356 syntax to change your password is: 2357 ``set_password <protocol> <password>`` where <protocol> could be 2358 either "vnc" or "spice". 2359 2360 If you would like to change <protocol> password expiration, you 2361 should use ``expire_password <protocol> <expiration-time>`` 2362 where expiration time could be one of the following options: 2363 now, never, +seconds or UNIX time of expiration, e.g. +60 to 2364 make password expire in 60 seconds, or 1335196800 to make 2365 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for 2366 this date and time). 2367 2368 You can also use keywords "now" or "never" for the expiration 2369 time to allow <protocol> password to expire immediately or never 2370 expire. 2371 2372 ``password-secret=<secret-id>`` 2373 Require that password based authentication is used for client 2374 connections, using the password provided by the ``secret`` 2375 object identified by ``secret-id``. 2376 2377 ``tls-creds=ID`` 2378 Provides the ID of a set of TLS credentials to use to secure the 2379 VNC server. They will apply to both the normal VNC server socket 2380 and the websocket socket (if enabled). Setting TLS credentials 2381 will cause the VNC server socket to enable the VeNCrypt auth 2382 mechanism. The credentials should have been previously created 2383 using the ``-object tls-creds`` argument. 2384 2385 ``tls-authz=ID`` 2386 Provides the ID of the QAuthZ authorization object against which 2387 the client's x509 distinguished name will validated. This object 2388 is only resolved at time of use, so can be deleted and recreated 2389 on the fly while the VNC server is active. If missing, it will 2390 default to denying access. 2391 2392 ``sasl=on|off`` 2393 Require that the client use SASL to authenticate with the VNC 2394 server. The exact choice of authentication method used is 2395 controlled from the system / user's SASL configuration file for 2396 the 'qemu' service. This is typically found in 2397 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, 2398 an environment variable SASL\_CONF\_PATH can be used to make it 2399 search alternate locations for the service config. While some 2400 SASL auth methods can also provide data encryption (eg GSSAPI), 2401 it is recommended that SASL always be combined with the 'tls' 2402 and 'x509' settings to enable use of SSL and server 2403 certificates. This ensures a data encryption preventing 2404 compromise of authentication credentials. See the 2405 :ref:`VNC security` section in the System Emulation Users Guide 2406 for details on using SASL authentication. 2407 2408 ``sasl-authz=ID`` 2409 Provides the ID of the QAuthZ authorization object against which 2410 the client's SASL username will validated. This object is only 2411 resolved at time of use, so can be deleted and recreated on the 2412 fly while the VNC server is active. If missing, it will default 2413 to denying access. 2414 2415 ``acl=on|off`` 2416 Legacy method for enabling authorization of clients against the 2417 x509 distinguished name and SASL username. It results in the 2418 creation of two ``authz-list`` objects with IDs of 2419 ``vnc.username`` and ``vnc.x509dname``. The rules for these 2420 objects must be configured with the HMP ACL commands. 2421 2422 This option is deprecated and should no longer be used. The new 2423 ``sasl-authz`` and ``tls-authz`` options are a replacement. 2424 2425 ``lossy=on|off`` 2426 Enable lossy compression methods (gradient, JPEG, ...). If this 2427 option is set, VNC client may receive lossy framebuffer updates 2428 depending on its encoding settings. Enabling this option can 2429 save a lot of bandwidth at the expense of quality. 2430 2431 ``non-adaptive=on|off`` 2432 Disable adaptive encodings. Adaptive encodings are enabled by 2433 default. An adaptive encoding will try to detect frequently 2434 updated screen regions, and send updates in these regions using 2435 a lossy encoding (like JPEG). This can be really helpful to save 2436 bandwidth when playing videos. Disabling adaptive encodings 2437 restores the original static behavior of encodings like Tight. 2438 2439 ``share=[allow-exclusive|force-shared|ignore]`` 2440 Set display sharing policy. 'allow-exclusive' allows clients to 2441 ask for exclusive access. As suggested by the rfb spec this is 2442 implemented by dropping other connections. Connecting multiple 2443 clients in parallel requires all clients asking for a shared 2444 session (vncviewer: -shared switch). This is the default. 2445 'force-shared' disables exclusive client access. Useful for 2446 shared desktop sessions, where you don't want someone forgetting 2447 specify -shared disconnect everybody else. 'ignore' completely 2448 ignores the shared flag and allows everybody connect 2449 unconditionally. Doesn't conform to the rfb spec but is 2450 traditional QEMU behavior. 2451 2452 ``key-delay-ms`` 2453 Set keyboard delay, for key down and key up events, in 2454 milliseconds. Default is 10. Keyboards are low-bandwidth 2455 devices, so this slowdown can help the device and guest to keep 2456 up and not lose events in case events are arriving in bulk. 2457 Possible causes for the latter are flaky network connections, or 2458 scripts for automated testing. 2459 2460 ``audiodev=audiodev`` 2461 Use the specified audiodev when the VNC client requests audio 2462 transmission. When not using an -audiodev argument, this option 2463 must be omitted, otherwise is must be present and specify a 2464 valid audiodev. 2465 2466 ``power-control=on|off`` 2467 Permit the remote client to issue shutdown, reboot or reset power 2468 control requests. 2469ERST 2470 2471ARCHHEADING(, QEMU_ARCH_I386) 2472 2473ARCHHEADING(i386 target only:, QEMU_ARCH_I386) 2474 2475DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack, 2476 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n", 2477 QEMU_ARCH_I386) 2478SRST 2479``-win2k-hack`` 2480 Use it when installing Windows 2000 to avoid a disk full bug. After 2481 Windows 2000 is installed, you no longer need this option (this 2482 option slows down the IDE transfers). 2483ERST 2484 2485DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk, 2486 "-no-fd-bootchk disable boot signature checking for floppy disks\n", 2487 QEMU_ARCH_I386) 2488SRST 2489``-no-fd-bootchk`` 2490 Disable boot signature checking for floppy disks in BIOS. May be 2491 needed to boot from old floppy disks. 2492ERST 2493 2494DEF("no-acpi", 0, QEMU_OPTION_no_acpi, 2495 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2496SRST 2497``-no-acpi`` 2498 Disable ACPI (Advanced Configuration and Power Interface) support. 2499 Use it if your guest OS complains about ACPI problems (PC target 2500 machine only). 2501ERST 2502 2503DEF("no-hpet", 0, QEMU_OPTION_no_hpet, 2504 "-no-hpet disable HPET\n", QEMU_ARCH_I386) 2505SRST 2506``-no-hpet`` 2507 Disable HPET support. 2508ERST 2509 2510DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable, 2511 "-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" 2512 " ACPI table description\n", QEMU_ARCH_I386) 2513SRST 2514``-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]...]`` 2515 Add ACPI table with specified header fields and context from 2516 specified files. For file=, take whole ACPI table from the specified 2517 files, including all ACPI headers (possible overridden by other 2518 options). For data=, only data portion of the table is used, all 2519 header information is specified in the command line. If a SLIC table 2520 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id 2521 fields will override the same in the RSDT and the FADT (a.k.a. 2522 FACP), in order to ensure the field matches required by the 2523 Microsoft SLIC spec and the ACPI spec. 2524ERST 2525 2526DEF("smbios", HAS_ARG, QEMU_OPTION_smbios, 2527 "-smbios file=binary\n" 2528 " load SMBIOS entry from binary file\n" 2529 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n" 2530 " [,uefi=on|off]\n" 2531 " specify SMBIOS type 0 fields\n" 2532 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2533 " [,uuid=uuid][,sku=str][,family=str]\n" 2534 " specify SMBIOS type 1 fields\n" 2535 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2536 " [,asset=str][,location=str]\n" 2537 " specify SMBIOS type 2 fields\n" 2538 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n" 2539 " [,sku=str]\n" 2540 " specify SMBIOS type 3 fields\n" 2541 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n" 2542 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n" 2543 " [,processor-id=%d]\n" 2544 " specify SMBIOS type 4 fields\n" 2545 "-smbios type=11[,value=str][,path=filename]\n" 2546 " specify SMBIOS type 11 fields\n" 2547 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n" 2548 " [,asset=str][,part=str][,speed=%d]\n" 2549 " specify SMBIOS type 17 fields\n" 2550 "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n" 2551 " specify SMBIOS type 41 fields\n", 2552 QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2553SRST 2554``-smbios file=binary`` 2555 Load SMBIOS entry from binary file. 2556 2557``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]`` 2558 Specify SMBIOS type 0 fields 2559 2560``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]`` 2561 Specify SMBIOS type 1 fields 2562 2563``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]`` 2564 Specify SMBIOS type 2 fields 2565 2566``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]`` 2567 Specify SMBIOS type 3 fields 2568 2569``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str][,processor-id=%d]`` 2570 Specify SMBIOS type 4 fields 2571 2572``-smbios type=11[,value=str][,path=filename]`` 2573 Specify SMBIOS type 11 fields 2574 2575 This argument can be repeated multiple times, and values are added in the order they are parsed. 2576 Applications intending to use OEM strings data are encouraged to use their application name as 2577 a prefix for the value string. This facilitates passing information for multiple applications 2578 concurrently. 2579 2580 The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax 2581 loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes. 2582 2583 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to 2584 the SMBIOS table in the order in which they appear. 2585 2586 Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535 2587 bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the 2588 guest. Instead it should be used as a indicator to inform the guest where to locate the real 2589 data set, for example, by specifying the serial ID of a block device. 2590 2591 An example passing three strings is 2592 2593 .. parsed-literal:: 2594 2595 -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\ 2596 value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\ 2597 path=/some/file/with/oemstringsdata.txt 2598 2599 In the guest OS this is visible with the ``dmidecode`` command 2600 2601 .. parsed-literal:: 2602 2603 $ dmidecode -t 11 2604 Handle 0x0E00, DMI type 11, 5 bytes 2605 OEM Strings 2606 String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/ 2607 String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os 2608 String 3: myapp:some extra data 2609 2610 2611``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]`` 2612 Specify SMBIOS type 17 fields 2613 2614``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]`` 2615 Specify SMBIOS type 41 fields 2616 2617 This argument can be repeated multiple times. Its main use is to allow network interfaces be created 2618 as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface 2619 position on the PCI bus. 2620 2621 Here is an example of use: 2622 2623 .. parsed-literal:: 2624 2625 -netdev user,id=internet \\ 2626 -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\ 2627 -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev 2628 2629 In the guest OS, the device should then appear as ``eno1``: 2630 2631 ..parsed-literal:: 2632 2633 $ ip -brief l 2634 lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP> 2635 eno1 UP 50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP> 2636 2637 Currently, the PCI device has to be attached to the root bus. 2638 2639ERST 2640 2641DEFHEADING() 2642 2643DEFHEADING(Network options:) 2644 2645DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, 2646#ifdef CONFIG_SLIRP 2647 "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n" 2648 " [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n" 2649 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n" 2650 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n" 2651 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]" 2652#ifndef _WIN32 2653 "[,smb=dir[,smbserver=addr]]\n" 2654#endif 2655 " configure a user mode network backend with ID 'str',\n" 2656 " its DHCP server and optional services\n" 2657#endif 2658#ifdef _WIN32 2659 "-netdev tap,id=str,ifname=name\n" 2660 " configure a host TAP network backend with ID 'str'\n" 2661#else 2662 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n" 2663 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" 2664 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" 2665 " [,poll-us=n]\n" 2666 " configure a host TAP network backend with ID 'str'\n" 2667 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2668 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n" 2669 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n" 2670 " to deconfigure it\n" 2671 " use '[down]script=no' to disable script execution\n" 2672 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n" 2673 " configure it\n" 2674 " use 'fd=h' to connect to an already opened TAP interface\n" 2675 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n" 2676 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n" 2677 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n" 2678 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" 2679 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" 2680 " use vhost=on to enable experimental in kernel accelerator\n" 2681 " (only has effect for virtio guests which use MSIX)\n" 2682 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" 2683 " use 'vhostfd=h' to connect to an already opened vhost net device\n" 2684 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n" 2685 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n" 2686 " use 'poll-us=n' to specify the maximum number of microseconds that could be\n" 2687 " spent on busy polling for vhost net\n" 2688 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n" 2689 " configure a host TAP network backend with ID 'str' that is\n" 2690 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2691 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n" 2692#endif 2693#ifdef __linux__ 2694 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n" 2695 " [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n" 2696 " [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n" 2697 " [,rxcookie=rxcookie][,offset=offset]\n" 2698 " configure a network backend with ID 'str' connected to\n" 2699 " an Ethernet over L2TPv3 pseudowire.\n" 2700 " Linux kernel 3.3+ as well as most routers can talk\n" 2701 " L2TPv3. This transport allows connecting a VM to a VM,\n" 2702 " VM to a router and even VM to Host. It is a nearly-universal\n" 2703 " standard (RFC3931). Note - this implementation uses static\n" 2704 " pre-configured tunnels (same as the Linux kernel).\n" 2705 " use 'src=' to specify source address\n" 2706 " use 'dst=' to specify destination address\n" 2707 " use 'udp=on' to specify udp encapsulation\n" 2708 " use 'srcport=' to specify source udp port\n" 2709 " use 'dstport=' to specify destination udp port\n" 2710 " use 'ipv6=on' to force v6\n" 2711 " L2TPv3 uses cookies to prevent misconfiguration as\n" 2712 " well as a weak security measure\n" 2713 " use 'rxcookie=0x012345678' to specify a rxcookie\n" 2714 " use 'txcookie=0x012345678' to specify a txcookie\n" 2715 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n" 2716 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n" 2717 " use 'pincounter=on' to work around broken counter handling in peer\n" 2718 " use 'offset=X' to add an extra offset between header and data\n" 2719#endif 2720 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n" 2721 " configure a network backend to connect to another network\n" 2722 " using a socket connection\n" 2723 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n" 2724 " configure a network backend to connect to a multicast maddr and port\n" 2725 " use 'localaddr=addr' to specify the host address to send packets from\n" 2726 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n" 2727 " configure a network backend to connect to another network\n" 2728 " using an UDP tunnel\n" 2729#ifdef CONFIG_VDE 2730 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n" 2731 " configure a network backend to connect to port 'n' of a vde switch\n" 2732 " running on host and listening for incoming connections on 'socketpath'.\n" 2733 " Use group 'groupname' and mode 'octalmode' to change default\n" 2734 " ownership and permissions for communication port.\n" 2735#endif 2736#ifdef CONFIG_NETMAP 2737 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n" 2738 " attach to the existing netmap-enabled network interface 'name', or to a\n" 2739 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n" 2740 " netmap device, defaults to '/dev/netmap')\n" 2741#endif 2742#ifdef CONFIG_POSIX 2743 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" 2744 " configure a vhost-user network, backed by a chardev 'dev'\n" 2745#endif 2746#ifdef __linux__ 2747 "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n" 2748 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n" 2749#endif 2750#ifdef CONFIG_VMNET 2751 "-netdev vmnet-host,id=str[,isolated=on|off][,net-uuid=uuid]\n" 2752 " [,start-address=addr,end-address=addr,subnet-mask=mask]\n" 2753 " configure a vmnet network backend in host mode with ID 'str',\n" 2754 " isolate this interface from others with 'isolated',\n" 2755 " configure the address range and choose a subnet mask,\n" 2756 " specify network UUID 'uuid' to disable DHCP and interact with\n" 2757 " vmnet-host interfaces within this isolated network\n" 2758 "-netdev vmnet-shared,id=str[,isolated=on|off][,nat66-prefix=addr]\n" 2759 " [,start-address=addr,end-address=addr,subnet-mask=mask]\n" 2760 " configure a vmnet network backend in shared mode with ID 'str',\n" 2761 " configure the address range and choose a subnet mask,\n" 2762 " set IPv6 ULA prefix (of length 64) to use for internal network,\n" 2763 " isolate this interface from others with 'isolated'\n" 2764 "-netdev vmnet-bridged,id=str,ifname=name[,isolated=on|off]\n" 2765 " configure a vmnet network backend in bridged mode with ID 'str',\n" 2766 " use 'ifname=name' to select a physical network interface to be bridged,\n" 2767 " isolate this interface from others with 'isolated'\n" 2768#endif 2769 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n" 2770 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL) 2771DEF("nic", HAS_ARG, QEMU_OPTION_nic, 2772 "-nic [tap|bridge|" 2773#ifdef CONFIG_SLIRP 2774 "user|" 2775#endif 2776#ifdef __linux__ 2777 "l2tpv3|" 2778#endif 2779#ifdef CONFIG_VDE 2780 "vde|" 2781#endif 2782#ifdef CONFIG_NETMAP 2783 "netmap|" 2784#endif 2785#ifdef CONFIG_POSIX 2786 "vhost-user|" 2787#endif 2788#ifdef CONFIG_VMNET 2789 "vmnet-host|vmnet-shared|vmnet-bridged|" 2790#endif 2791 "socket][,option][,...][mac=macaddr]\n" 2792 " initialize an on-board / default host NIC (using MAC address\n" 2793 " macaddr) and connect it to the given host network backend\n" 2794 "-nic none use it alone to have zero network devices (the default is to\n" 2795 " provided a 'user' network connection)\n", 2796 QEMU_ARCH_ALL) 2797DEF("net", HAS_ARG, QEMU_OPTION_net, 2798 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" 2799 " configure or create an on-board (or machine default) NIC and\n" 2800 " connect it to hub 0 (please use -nic unless you need a hub)\n" 2801 "-net [" 2802#ifdef CONFIG_SLIRP 2803 "user|" 2804#endif 2805 "tap|" 2806 "bridge|" 2807#ifdef CONFIG_VDE 2808 "vde|" 2809#endif 2810#ifdef CONFIG_NETMAP 2811 "netmap|" 2812#endif 2813#ifdef CONFIG_VMNET 2814 "vmnet-host|vmnet-shared|vmnet-bridged|" 2815#endif 2816 "socket][,option][,option][,...]\n" 2817 " old way to initialize a host network interface\n" 2818 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL) 2819SRST 2820``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]`` 2821 This option is a shortcut for configuring both the on-board 2822 (default) guest NIC hardware and the host network backend in one go. 2823 The host backend options are the same as with the corresponding 2824 ``-netdev`` options below. The guest NIC model can be set with 2825 ``model=modelname``. Use ``model=help`` to list the available device 2826 types. The hardware MAC address can be set with ``mac=macaddr``. 2827 2828 The following two example do exactly the same, to show how ``-nic`` 2829 can be used to shorten the command line length: 2830 2831 .. parsed-literal:: 2832 2833 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32 2834 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32 2835 2836``-nic none`` 2837 Indicate that no network devices should be configured. It is used to 2838 override the default configuration (default NIC with "user" host 2839 network backend) which is activated if no other networking options 2840 are provided. 2841 2842``-netdev user,id=id[,option][,option][,...]`` 2843 Configure user mode host network backend which requires no 2844 administrator privilege to run. Valid options are: 2845 2846 ``id=id`` 2847 Assign symbolic name for use in monitor commands. 2848 2849 ``ipv4=on|off and ipv6=on|off`` 2850 Specify that either IPv4 or IPv6 must be enabled. If neither is 2851 specified both protocols are enabled. 2852 2853 ``net=addr[/mask]`` 2854 Set IP network address the guest will see. Optionally specify 2855 the netmask, either in the form a.b.c.d or as number of valid 2856 top-most bits. Default is 10.0.2.0/24. 2857 2858 ``host=addr`` 2859 Specify the guest-visible address of the host. Default is the 2860 2nd IP in the guest network, i.e. x.x.x.2. 2861 2862 ``ipv6-net=addr[/int]`` 2863 Set IPv6 network address the guest will see (default is 2864 fec0::/64). The network prefix is given in the usual hexadecimal 2865 IPv6 address notation. The prefix size is optional, and is given 2866 as the number of valid top-most bits (default is 64). 2867 2868 ``ipv6-host=addr`` 2869 Specify the guest-visible IPv6 address of the host. Default is 2870 the 2nd IPv6 in the guest network, i.e. xxxx::2. 2871 2872 ``restrict=on|off`` 2873 If this option is enabled, the guest will be isolated, i.e. it 2874 will not be able to contact the host and no guest IP packets 2875 will be routed over the host to the outside. This option does 2876 not affect any explicitly set forwarding rules. 2877 2878 ``hostname=name`` 2879 Specifies the client hostname reported by the built-in DHCP 2880 server. 2881 2882 ``dhcpstart=addr`` 2883 Specify the first of the 16 IPs the built-in DHCP server can 2884 assign. Default is the 15th to 31st IP in the guest network, 2885 i.e. x.x.x.15 to x.x.x.31. 2886 2887 ``dns=addr`` 2888 Specify the guest-visible address of the virtual nameserver. The 2889 address must be different from the host address. Default is the 2890 3rd IP in the guest network, i.e. x.x.x.3. 2891 2892 ``ipv6-dns=addr`` 2893 Specify the guest-visible address of the IPv6 virtual 2894 nameserver. The address must be different from the host address. 2895 Default is the 3rd IP in the guest network, i.e. xxxx::3. 2896 2897 ``dnssearch=domain`` 2898 Provides an entry for the domain-search list sent by the 2899 built-in DHCP server. More than one domain suffix can be 2900 transmitted by specifying this option multiple times. If 2901 supported, this will cause the guest to automatically try to 2902 append the given domain suffix(es) in case a domain name can not 2903 be resolved. 2904 2905 Example: 2906 2907 .. parsed-literal:: 2908 2909 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org 2910 2911 ``domainname=domain`` 2912 Specifies the client domain name reported by the built-in DHCP 2913 server. 2914 2915 ``tftp=dir`` 2916 When using the user mode network stack, activate a built-in TFTP 2917 server. The files in dir will be exposed as the root of a TFTP 2918 server. The TFTP client on the guest must be configured in 2919 binary mode (use the command ``bin`` of the Unix TFTP client). 2920 2921 ``tftp-server-name=name`` 2922 In BOOTP reply, broadcast name as the "TFTP server name" 2923 (RFC2132 option 66). This can be used to advise the guest to 2924 load boot files or configurations from a different server than 2925 the host address. 2926 2927 ``bootfile=file`` 2928 When using the user mode network stack, broadcast file as the 2929 BOOTP filename. In conjunction with ``tftp``, this can be used 2930 to network boot a guest from a local directory. 2931 2932 Example (using pxelinux): 2933 2934 .. parsed-literal:: 2935 2936 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\ 2937 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0 2938 2939 ``smb=dir[,smbserver=addr]`` 2940 When using the user mode network stack, activate a built-in SMB 2941 server so that Windows OSes can access to the host files in 2942 ``dir`` transparently. The IP address of the SMB server can be 2943 set to addr. By default the 4th IP in the guest network is used, 2944 i.e. x.x.x.4. 2945 2946 In the guest Windows OS, the line: 2947 2948 :: 2949 2950 10.0.2.4 smbserver 2951 2952 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows 2953 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows 2954 NT/2000). 2955 2956 Then ``dir`` can be accessed in ``\\smbserver\qemu``. 2957 2958 Note that a SAMBA server must be installed on the host OS. 2959 2960 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport`` 2961 Redirect incoming TCP or UDP connections to the host port 2962 hostport to the guest IP address guestaddr on guest port 2963 guestport. If guestaddr is not specified, its value is x.x.x.15 2964 (default first address given by the built-in DHCP server). By 2965 specifying hostaddr, the rule can be bound to a specific host 2966 interface. If no connection type is set, TCP is used. This 2967 option can be given multiple times. 2968 2969 For example, to redirect host X11 connection from screen 1 to 2970 guest screen 0, use the following: 2971 2972 .. parsed-literal:: 2973 2974 # on the host 2975 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000 2976 # this host xterm should open in the guest X11 server 2977 xterm -display :1 2978 2979 To redirect telnet connections from host port 5555 to telnet 2980 port on the guest, use the following: 2981 2982 .. parsed-literal:: 2983 2984 # on the host 2985 |qemu_system| -nic user,hostfwd=tcp::5555-:23 2986 telnet localhost 5555 2987 2988 Then when you use on the host ``telnet localhost 5555``, you 2989 connect to the guest telnet server. 2990 2991 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command`` 2992 Forward guest TCP connections to the IP address server on port 2993 port to the character device dev or to a program executed by 2994 cmd:command which gets spawned for each connection. This option 2995 can be given multiple times. 2996 2997 You can either use a chardev directly and have that one used 2998 throughout QEMU's lifetime, like in the following example: 2999 3000 .. parsed-literal:: 3001 3002 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever 3003 # the guest accesses it 3004 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 3005 3006 Or you can execute a command on every TCP connection established 3007 by the guest, so that QEMU behaves similar to an inetd process 3008 for that virtual server: 3009 3010 .. parsed-literal:: 3011 3012 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234 3013 # and connect the TCP stream to its stdin/stdout 3014 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321' 3015 3016``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]`` 3017 Configure a host TAP network backend with ID id. 3018 3019 Use the network script file to configure it and the network script 3020 dfile to deconfigure it. If name is not provided, the OS 3021 automatically provides one. The default network configure script is 3022 ``/etc/qemu-ifup`` and the default network deconfigure script is 3023 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to 3024 disable script execution. 3025 3026 If running QEMU as an unprivileged user, use the network helper 3027 to configure the TAP interface and attach it to the bridge. 3028 The default network helper executable is 3029 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3030 ``br0``. 3031 3032 ``fd``\ =h can be used to specify the handle of an already opened 3033 host TAP interface. 3034 3035 Examples: 3036 3037 .. parsed-literal:: 3038 3039 #launch a QEMU instance with the default network script 3040 |qemu_system| linux.img -nic tap 3041 3042 .. parsed-literal:: 3043 3044 #launch a QEMU instance with two NICs, each one connected 3045 #to a TAP device 3046 |qemu_system| linux.img \\ 3047 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\ 3048 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1 3049 3050 .. parsed-literal:: 3051 3052 #launch a QEMU instance with the default network helper to 3053 #connect a TAP device to bridge br0 3054 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\ 3055 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper" 3056 3057``-netdev bridge,id=id[,br=bridge][,helper=helper]`` 3058 Connect a host TAP network interface to a host bridge device. 3059 3060 Use the network helper helper to configure the TAP interface and 3061 attach it to the bridge. The default network helper executable is 3062 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3063 ``br0``. 3064 3065 Examples: 3066 3067 .. parsed-literal:: 3068 3069 #launch a QEMU instance with the default network helper to 3070 #connect a TAP device to bridge br0 3071 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1 3072 3073 .. parsed-literal:: 3074 3075 #launch a QEMU instance with the default network helper to 3076 #connect a TAP device to bridge qemubr0 3077 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1 3078 3079``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]`` 3080 This host network backend can be used to connect the guest's network 3081 to another QEMU virtual machine using a TCP socket connection. If 3082 ``listen`` is specified, QEMU waits for incoming connections on port 3083 (host is optional). ``connect`` is used to connect to another QEMU 3084 instance using the ``listen`` option. ``fd``\ =h specifies an 3085 already opened TCP socket. 3086 3087 Example: 3088 3089 .. parsed-literal:: 3090 3091 # launch a first QEMU instance 3092 |qemu_system| linux.img \\ 3093 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3094 -netdev socket,id=n1,listen=:1234 3095 # connect the network of this instance to the network of the first instance 3096 |qemu_system| linux.img \\ 3097 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3098 -netdev socket,id=n2,connect=127.0.0.1:1234 3099 3100``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]`` 3101 Configure a socket host network backend to share the guest's network 3102 traffic with another QEMU virtual machines using a UDP multicast 3103 socket, effectively making a bus for every QEMU with same multicast 3104 address maddr and port. NOTES: 3105 3106 1. Several QEMU can be running on different hosts and share same bus 3107 (assuming correct multicast setup for these hosts). 3108 3109 2. mcast support is compatible with User Mode Linux (argument 3110 ``ethN=mcast``), see http://user-mode-linux.sf.net. 3111 3112 3. Use ``fd=h`` to specify an already opened UDP multicast socket. 3113 3114 Example: 3115 3116 .. parsed-literal:: 3117 3118 # launch one QEMU instance 3119 |qemu_system| linux.img \\ 3120 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3121 -netdev socket,id=n1,mcast=230.0.0.1:1234 3122 # launch another QEMU instance on same "bus" 3123 |qemu_system| linux.img \\ 3124 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3125 -netdev socket,id=n2,mcast=230.0.0.1:1234 3126 # launch yet another QEMU instance on same "bus" 3127 |qemu_system| linux.img \\ 3128 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\ 3129 -netdev socket,id=n3,mcast=230.0.0.1:1234 3130 3131 Example (User Mode Linux compat.): 3132 3133 .. parsed-literal:: 3134 3135 # launch QEMU instance (note mcast address selected is UML's default) 3136 |qemu_system| linux.img \\ 3137 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3138 -netdev socket,id=n1,mcast=239.192.168.1:1102 3139 # launch UML 3140 /path/to/linux ubd0=/path/to/root_fs eth0=mcast 3141 3142 Example (send packets from host's 1.2.3.4): 3143 3144 .. parsed-literal:: 3145 3146 |qemu_system| linux.img \\ 3147 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3148 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4 3149 3150``-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]`` 3151 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931) 3152 is a popular protocol to transport Ethernet (and other Layer 2) data 3153 frames between two systems. It is present in routers, firewalls and 3154 the Linux kernel (from version 3.3 onwards). 3155 3156 This transport allows a VM to communicate to another VM, router or 3157 firewall directly. 3158 3159 ``src=srcaddr`` 3160 source address (mandatory) 3161 3162 ``dst=dstaddr`` 3163 destination address (mandatory) 3164 3165 ``udp`` 3166 select udp encapsulation (default is ip). 3167 3168 ``srcport=srcport`` 3169 source udp port. 3170 3171 ``dstport=dstport`` 3172 destination udp port. 3173 3174 ``ipv6`` 3175 force v6, otherwise defaults to v4. 3176 3177 ``rxcookie=rxcookie``; \ ``txcookie=txcookie`` 3178 Cookies are a weak form of security in the l2tpv3 specification. 3179 Their function is mostly to prevent misconfiguration. By default 3180 they are 32 bit. 3181 3182 ``cookie64`` 3183 Set cookie size to 64 bit instead of the default 32 3184 3185 ``counter=off`` 3186 Force a 'cut-down' L2TPv3 with no counter as in 3187 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00 3188 3189 ``pincounter=on`` 3190 Work around broken counter handling in peer. This may also help 3191 on networks which have packet reorder. 3192 3193 ``offset=offset`` 3194 Add an extra offset between header and data 3195 3196 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to 3197 the bridge br-lan on the remote Linux host 1.2.3.4: 3198 3199 .. parsed-literal:: 3200 3201 # Setup tunnel on linux host using raw ip as encapsulation 3202 # on 1.2.3.4 3203 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\ 3204 encap udp udp_sport 16384 udp_dport 16384 3205 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\ 3206 0xFFFFFFFF peer_session_id 0xFFFFFFFF 3207 ifconfig vmtunnel0 mtu 1500 3208 ifconfig vmtunnel0 up 3209 brctl addif br-lan vmtunnel0 3210 3211 3212 # on 4.3.2.1 3213 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter 3214 3215 |qemu_system| linux.img -device e1000,netdev=n1 \\ 3216 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter 3217 3218``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]`` 3219 Configure VDE backend to connect to PORT n of a vde switch running 3220 on host and listening for incoming connections on socketpath. Use 3221 GROUP groupname and MODE octalmode to change default ownership and 3222 permissions for communication port. This option is only available if 3223 QEMU has been compiled with vde support enabled. 3224 3225 Example: 3226 3227 .. parsed-literal:: 3228 3229 # launch vde switch 3230 vde_switch -F -sock /tmp/myswitch 3231 # launch QEMU instance 3232 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch 3233 3234``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]`` 3235 Establish a vhost-user netdev, backed by a chardev id. The chardev 3236 should be a unix domain socket backed one. The vhost-user uses a 3237 specifically defined protocol to pass vhost ioctl replacement 3238 messages to an application on the other end of the socket. On 3239 non-MSIX guests, the feature can be forced with vhostforce. Use 3240 'queues=n' to specify the number of queues to be created for 3241 multiqueue vhost-user. 3242 3243 Example: 3244 3245 :: 3246 3247 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \ 3248 -numa node,memdev=mem \ 3249 -chardev socket,id=chr0,path=/path/to/socket \ 3250 -netdev type=vhost-user,id=net0,chardev=chr0 \ 3251 -device virtio-net-pci,netdev=net0 3252 3253``-netdev vhost-vdpa,vhostdev=/path/to/dev`` 3254 Establish a vhost-vdpa netdev. 3255 3256 vDPA device is a device that uses a datapath which complies with 3257 the virtio specifications with a vendor specific control path. 3258 vDPA devices can be both physically located on the hardware or 3259 emulated by software. 3260 3261``-netdev hubport,id=id,hubid=hubid[,netdev=nd]`` 3262 Create a hub port on the emulated hub with ID hubid. 3263 3264 The hubport netdev lets you connect a NIC to a QEMU emulated hub 3265 instead of a single netdev. Alternatively, you can also connect the 3266 hubport to another netdev with ID nd by using the ``netdev=nd`` 3267 option. 3268 3269``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]`` 3270 Legacy option to configure or create an on-board (or machine 3271 default) Network Interface Card(NIC) and connect it either to the 3272 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd. 3273 If model is omitted, then the default NIC model associated with the 3274 machine type is used. Note that the default NIC model may change in 3275 future QEMU releases, so it is highly recommended to always specify 3276 a model. Optionally, the MAC address can be changed to mac, the 3277 device address set to addr (PCI cards only), and a name can be 3278 assigned for use in monitor commands. Optionally, for PCI cards, you 3279 can specify the number v of MSI-X vectors that the card should have; 3280 this option currently only affects virtio cards; set v = 0 to 3281 disable MSI-X. If no ``-net`` option is specified, a single NIC is 3282 created. QEMU can emulate several different models of network card. 3283 Use ``-net nic,model=help`` for a list of available devices for your 3284 target. 3285 3286``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]`` 3287 Configure a host network backend (with the options corresponding to 3288 the same ``-netdev`` option) and connect it to the emulated hub 0 3289 (the default hub). Use name to specify the name of the hub port. 3290ERST 3291 3292DEFHEADING() 3293 3294DEFHEADING(Character device options:) 3295 3296DEF("chardev", HAS_ARG, QEMU_OPTION_chardev, 3297 "-chardev help\n" 3298 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3299 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n" 3300 " [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n" 3301 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n" 3302 "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n" 3303 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n" 3304 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n" 3305 " [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n" 3306 " [,logfile=PATH][,logappend=on|off]\n" 3307 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3308 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n" 3309 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3310 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n" 3311 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3312 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3313#ifdef _WIN32 3314 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3315 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3316#else 3317 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3318 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n" 3319#endif 3320#ifdef CONFIG_BRLAPI 3321 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3322#endif 3323#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ 3324 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) 3325 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3326 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3327#endif 3328#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__) 3329 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3330 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3331#endif 3332#if defined(CONFIG_SPICE) 3333 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3334 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3335#endif 3336 , QEMU_ARCH_ALL 3337) 3338 3339SRST 3340The general form of a character device option is: 3341 3342``-chardev backend,id=id[,mux=on|off][,options]`` 3343 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, 3344 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``, 3345 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``, 3346 ``spicevmc``, ``spiceport``. The specific backend will determine the 3347 applicable options. 3348 3349 Use ``-chardev help`` to print all available chardev backend types. 3350 3351 All devices must have an id, which can be any string up to 127 3352 characters long. It is used to uniquely identify this device in 3353 other command line directives. 3354 3355 A character device may be used in multiplexing mode by multiple 3356 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is 3357 a "1:N" device, and here the "1" end is your specified chardev 3358 backend, and the "N" end is the various parts of QEMU that can talk 3359 to a chardev. If you create a chardev with ``id=myid`` and 3360 ``mux=on``, QEMU will create a multiplexer with your specified ID, 3361 and you can then configure multiple front ends to use that chardev 3362 ID for their input/output. Up to four different front ends can be 3363 connected to a single multiplexed chardev. (Without multiplexing 3364 enabled, a chardev can only be used by a single front end.) For 3365 instance you could use this to allow a single stdio chardev to be 3366 used by two serial ports and the QEMU monitor: 3367 3368 :: 3369 3370 -chardev stdio,mux=on,id=char0 \ 3371 -mon chardev=char0,mode=readline \ 3372 -serial chardev:char0 \ 3373 -serial chardev:char0 3374 3375 You can have more than one multiplexer in a system configuration; 3376 for instance you could have a TCP port multiplexed between UART 0 3377 and UART 1, and stdio multiplexed between the QEMU monitor and a 3378 parallel port: 3379 3380 :: 3381 3382 -chardev stdio,mux=on,id=char0 \ 3383 -mon chardev=char0,mode=readline \ 3384 -parallel chardev:char0 \ 3385 -chardev tcp,...,mux=on,id=char1 \ 3386 -serial chardev:char1 \ 3387 -serial chardev:char1 3388 3389 When you're using a multiplexed character device, some escape 3390 sequences are interpreted in the input. See the chapter about 3391 :ref:`keys in the character backend multiplexer` in the 3392 System Emulation Users Guide for more details. 3393 3394 Note that some other command line options may implicitly create 3395 multiplexed character backends; for instance ``-serial mon:stdio`` 3396 creates a multiplexed stdio backend connected to the serial port and 3397 the QEMU monitor, and ``-nographic`` also multiplexes the console 3398 and the monitor to stdio. 3399 3400 There is currently no support for multiplexing in the other 3401 direction (where a single QEMU front end takes input and output from 3402 multiple chardevs). 3403 3404 Every backend supports the ``logfile`` option, which supplies the 3405 path to a file to record all data transmitted via the backend. The 3406 ``logappend`` option controls whether the log file will be truncated 3407 or appended to when opened. 3408 3409The available backends are: 3410 3411``-chardev null,id=id`` 3412 A void device. This device will not emit any data, and will drop any 3413 data it receives. The null backend does not take any options. 3414 3415``-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]`` 3416 Create a two-way stream socket, which can be either a TCP or a unix 3417 socket. A unix socket will be created if ``path`` is specified. 3418 Behaviour is undefined if TCP options are specified for a unix 3419 socket. 3420 3421 ``server=on|off`` specifies that the socket shall be a listening socket. 3422 3423 ``wait=on|off`` specifies that QEMU should not block waiting for a client 3424 to connect to a listening socket. 3425 3426 ``telnet=on|off`` specifies that traffic on the socket should interpret 3427 telnet escape sequences. 3428 3429 ``websocket=on|off`` specifies that the socket uses WebSocket protocol for 3430 communication. 3431 3432 ``reconnect`` sets the timeout for reconnecting on non-server 3433 sockets when the remote end goes away. qemu will delay this many 3434 seconds and then attempt to reconnect. Zero disables reconnecting, 3435 and is the default. 3436 3437 ``tls-creds`` requests enablement of the TLS protocol for 3438 encryption, and specifies the id of the TLS credentials to use for 3439 the handshake. The credentials must be previously created with the 3440 ``-object tls-creds`` argument. 3441 3442 ``tls-auth`` provides the ID of the QAuthZ authorization object 3443 against which the client's x509 distinguished name will be 3444 validated. This object is only resolved at time of use, so can be 3445 deleted and recreated on the fly while the chardev server is active. 3446 If missing, it will default to denying access. 3447 3448 TCP and unix socket options are given below: 3449 3450 ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]`` 3451 ``host`` for a listening socket specifies the local address to 3452 be bound. For a connecting socket species the remote host to 3453 connect to. ``host`` is optional for listening sockets. If not 3454 specified it defaults to ``0.0.0.0``. 3455 3456 ``port`` for a listening socket specifies the local port to be 3457 bound. For a connecting socket specifies the port on the remote 3458 host to connect to. ``port`` can be given as either a port 3459 number or a service name. ``port`` is required. 3460 3461 ``to`` is only relevant to listening sockets. If it is 3462 specified, and ``port`` cannot be bound, QEMU will attempt to 3463 bind to subsequent ports up to and including ``to`` until it 3464 succeeds. ``to`` must be specified as a port number. 3465 3466 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 3467 or IPv6 must be used. If neither is specified the socket may 3468 use either protocol. 3469 3470 ``nodelay=on|off`` disables the Nagle algorithm. 3471 3472 ``unix options: path=path[,abstract=on|off][,tight=on|off]`` 3473 ``path`` specifies the local path of the unix socket. ``path`` 3474 is required. 3475 ``abstract=on|off`` specifies the use of the abstract socket namespace, 3476 rather than the filesystem. Optional, defaults to false. 3477 ``tight=on|off`` sets the socket length of abstract sockets to their minimum, 3478 rather than the full sun_path length. Optional, defaults to true. 3479 3480``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]`` 3481 Sends all traffic from the guest to a remote host over UDP. 3482 3483 ``host`` specifies the remote host to connect to. If not specified 3484 it defaults to ``localhost``. 3485 3486 ``port`` specifies the port on the remote host to connect to. 3487 ``port`` is required. 3488 3489 ``localaddr`` specifies the local address to bind to. If not 3490 specified it defaults to ``0.0.0.0``. 3491 3492 ``localport`` specifies the local port to bind to. If not specified 3493 any available local port will be used. 3494 3495 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used. 3496 If neither is specified the device may use either protocol. 3497 3498``-chardev msmouse,id=id`` 3499 Forward QEMU's emulated msmouse events to the guest. ``msmouse`` 3500 does not take any options. 3501 3502``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]`` 3503 Connect to a QEMU text console. ``vc`` may optionally be given a 3504 specific size. 3505 3506 ``width`` and ``height`` specify the width and height respectively 3507 of the console, in pixels. 3508 3509 ``cols`` and ``rows`` specify that the console be sized to fit a 3510 text console with the given dimensions. 3511 3512``-chardev ringbuf,id=id[,size=size]`` 3513 Create a ring buffer with fixed size ``size``. size must be a power 3514 of two and defaults to ``64K``. 3515 3516``-chardev file,id=id,path=path`` 3517 Log all traffic received from the guest to a file. 3518 3519 ``path`` specifies the path of the file to be opened. This file will 3520 be created if it does not already exist, and overwritten if it does. 3521 ``path`` is required. 3522 3523``-chardev pipe,id=id,path=path`` 3524 Create a two-way connection to the guest. The behaviour differs 3525 slightly between Windows hosts and other hosts: 3526 3527 On Windows, a single duplex pipe will be created at 3528 ``\\.pipe\path``. 3529 3530 On other hosts, 2 pipes will be created called ``path.in`` and 3531 ``path.out``. Data written to ``path.in`` will be received by the 3532 guest. Data written by the guest can be read from ``path.out``. QEMU 3533 will not create these fifos, and requires them to be present. 3534 3535 ``path`` forms part of the pipe path as described above. ``path`` is 3536 required. 3537 3538``-chardev console,id=id`` 3539 Send traffic from the guest to QEMU's standard output. ``console`` 3540 does not take any options. 3541 3542 ``console`` is only available on Windows hosts. 3543 3544``-chardev serial,id=id,path=path`` 3545 Send traffic from the guest to a serial device on the host. 3546 3547 On Unix hosts serial will actually accept any tty device, not only 3548 serial lines. 3549 3550 ``path`` specifies the name of the serial device to open. 3551 3552``-chardev pty,id=id`` 3553 Create a new pseudo-terminal on the host and connect to it. ``pty`` 3554 does not take any options. 3555 3556 ``pty`` is not available on Windows hosts. 3557 3558``-chardev stdio,id=id[,signal=on|off]`` 3559 Connect to standard input and standard output of the QEMU process. 3560 3561 ``signal`` controls if signals are enabled on the terminal, that 3562 includes exiting QEMU with the key sequence Control-c. This option 3563 is enabled by default, use ``signal=off`` to disable it. 3564 3565``-chardev braille,id=id`` 3566 Connect to a local BrlAPI server. ``braille`` does not take any 3567 options. 3568 3569``-chardev tty,id=id,path=path`` 3570 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD 3571 and DragonFlyBSD hosts. It is an alias for ``serial``. 3572 3573 ``path`` specifies the path to the tty. ``path`` is required. 3574 3575``-chardev parallel,id=id,path=path`` 3576 \ 3577``-chardev parport,id=id,path=path`` 3578 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD 3579 hosts. 3580 3581 Connect to a local parallel port. 3582 3583 ``path`` specifies the path to the parallel port device. ``path`` is 3584 required. 3585 3586``-chardev spicevmc,id=id,debug=debug,name=name`` 3587 ``spicevmc`` is only available when spice support is built in. 3588 3589 ``debug`` debug level for spicevmc 3590 3591 ``name`` name of spice channel to connect to 3592 3593 Connect to a spice virtual machine channel, such as vdiport. 3594 3595``-chardev spiceport,id=id,debug=debug,name=name`` 3596 ``spiceport`` is only available when spice support is built in. 3597 3598 ``debug`` debug level for spicevmc 3599 3600 ``name`` name of spice port to connect to 3601 3602 Connect to a spice port, allowing a Spice client to handle the 3603 traffic identified by a name (preferably a fqdn). 3604ERST 3605 3606DEFHEADING() 3607 3608#ifdef CONFIG_TPM 3609DEFHEADING(TPM device options:) 3610 3611DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \ 3612 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n" 3613 " use path to provide path to a character device; default is /dev/tpm0\n" 3614 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n" 3615 " not provided it will be searched for in /sys/class/misc/tpm?/device\n" 3616 "-tpmdev emulator,id=id,chardev=dev\n" 3617 " configure the TPM device using chardev backend\n", 3618 QEMU_ARCH_ALL) 3619SRST 3620The general form of a TPM device option is: 3621 3622``-tpmdev backend,id=id[,options]`` 3623 The specific backend type will determine the applicable options. The 3624 ``-tpmdev`` option creates the TPM backend and requires a 3625 ``-device`` option that specifies the TPM frontend interface model. 3626 3627 Use ``-tpmdev help`` to print all available TPM backend types. 3628 3629The available backends are: 3630 3631``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path`` 3632 (Linux-host only) Enable access to the host's TPM using the 3633 passthrough driver. 3634 3635 ``path`` specifies the path to the host's TPM device, i.e., on a 3636 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by 3637 default ``/dev/tpm0`` is used. 3638 3639 ``cancel-path`` specifies the path to the host TPM device's sysfs 3640 entry allowing for cancellation of an ongoing TPM command. 3641 ``cancel-path`` is optional and by default QEMU will search for the 3642 sysfs entry to use. 3643 3644 Some notes about using the host's TPM with the passthrough driver: 3645 3646 The TPM device accessed by the passthrough driver must not be used 3647 by any other application on the host. 3648 3649 Since the host's firmware (BIOS/UEFI) has already initialized the 3650 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize 3651 the TPM again and may therefore not show a TPM-specific menu that 3652 would otherwise allow the user to configure the TPM, e.g., allow the 3653 user to enable/disable or activate/deactivate the TPM. Further, if 3654 TPM ownership is released from within a VM then the host's TPM will 3655 get disabled and deactivated. To enable and activate the TPM again 3656 afterwards, the host has to be rebooted and the user is required to 3657 enter the firmware's menu to enable and activate the TPM. If the TPM 3658 is left disabled and/or deactivated most TPM commands will fail. 3659 3660 To create a passthrough TPM use the following two options: 3661 3662 :: 3663 3664 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0 3665 3666 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by 3667 ``tpmdev=tpm0`` in the device option. 3668 3669``-tpmdev emulator,id=id,chardev=dev`` 3670 (Linux-host only) Enable access to a TPM emulator using Unix domain 3671 socket based chardev backend. 3672 3673 ``chardev`` specifies the unique ID of a character device backend 3674 that provides connection to the software TPM server. 3675 3676 To create a TPM emulator backend device with chardev socket backend: 3677 3678 :: 3679 3680 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0 3681ERST 3682 3683DEFHEADING() 3684 3685#endif 3686 3687DEFHEADING(Linux/Multiboot boot specific:) 3688SRST 3689When using these options, you can use a given Linux or Multiboot kernel 3690without installing it in the disk image. It can be useful for easier 3691testing of various kernels. 3692 3693 3694ERST 3695 3696DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \ 3697 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL) 3698SRST 3699``-kernel bzImage`` 3700 Use bzImage as kernel image. The kernel can be either a Linux kernel 3701 or in multiboot format. 3702ERST 3703 3704DEF("append", HAS_ARG, QEMU_OPTION_append, \ 3705 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL) 3706SRST 3707``-append cmdline`` 3708 Use cmdline as kernel command line 3709ERST 3710 3711DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \ 3712 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL) 3713SRST 3714``-initrd file`` 3715 Use file as initial ram disk. 3716 3717``-initrd "file1 arg=foo,file2"`` 3718 This syntax is only available with multiboot. 3719 3720 Use file1 and file2 as modules and pass arg=foo as parameter to the 3721 first module. 3722ERST 3723 3724DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \ 3725 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL) 3726SRST 3727``-dtb file`` 3728 Use file as a device tree binary (dtb) image and pass it to the 3729 kernel on boot. 3730ERST 3731 3732DEFHEADING() 3733 3734DEFHEADING(Debug/Expert options:) 3735 3736DEF("compat", HAS_ARG, QEMU_OPTION_compat, 3737 "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n" 3738 " Policy for handling deprecated management interfaces\n" 3739 "-compat [unstable-input=accept|reject|crash][,unstable-output=accept|hide]\n" 3740 " Policy for handling unstable management interfaces\n", 3741 QEMU_ARCH_ALL) 3742SRST 3743``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]`` 3744 Set policy for handling deprecated management interfaces (experimental): 3745 3746 ``deprecated-input=accept`` (default) 3747 Accept deprecated commands and arguments 3748 ``deprecated-input=reject`` 3749 Reject deprecated commands and arguments 3750 ``deprecated-input=crash`` 3751 Crash on deprecated commands and arguments 3752 ``deprecated-output=accept`` (default) 3753 Emit deprecated command results and events 3754 ``deprecated-output=hide`` 3755 Suppress deprecated command results and events 3756 3757 Limitation: covers only syntactic aspects of QMP. 3758 3759``-compat [unstable-input=@var{input-policy}][,unstable-output=@var{output-policy}]`` 3760 Set policy for handling unstable management interfaces (experimental): 3761 3762 ``unstable-input=accept`` (default) 3763 Accept unstable commands and arguments 3764 ``unstable-input=reject`` 3765 Reject unstable commands and arguments 3766 ``unstable-input=crash`` 3767 Crash on unstable commands and arguments 3768 ``unstable-output=accept`` (default) 3769 Emit unstable command results and events 3770 ``unstable-output=hide`` 3771 Suppress unstable command results and events 3772 3773 Limitation: covers only syntactic aspects of QMP. 3774ERST 3775 3776DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg, 3777 "-fw_cfg [name=]<name>,file=<file>\n" 3778 " add named fw_cfg entry with contents from file\n" 3779 "-fw_cfg [name=]<name>,string=<str>\n" 3780 " add named fw_cfg entry with contents from string\n", 3781 QEMU_ARCH_ALL) 3782SRST 3783``-fw_cfg [name=]name,file=file`` 3784 Add named fw\_cfg entry with contents from file file. 3785 3786``-fw_cfg [name=]name,string=str`` 3787 Add named fw\_cfg entry with contents from string str. 3788 3789 The terminating NUL character of the contents of str will not be 3790 included as part of the fw\_cfg item data. To insert contents with 3791 embedded NUL characters, you have to use the file parameter. 3792 3793 The fw\_cfg entries are passed by QEMU through to the guest. 3794 3795 Example: 3796 3797 :: 3798 3799 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin 3800 3801 creates an fw\_cfg entry named opt/com.mycompany/blob with contents 3802 from ./my\_blob.bin. 3803ERST 3804 3805DEF("serial", HAS_ARG, QEMU_OPTION_serial, \ 3806 "-serial dev redirect the serial port to char device 'dev'\n", 3807 QEMU_ARCH_ALL) 3808SRST 3809``-serial dev`` 3810 Redirect the virtual serial port to host character device dev. The 3811 default device is ``vc`` in graphical mode and ``stdio`` in non 3812 graphical mode. 3813 3814 This option can be used several times to simulate up to 4 serial 3815 ports. 3816 3817 Use ``-serial none`` to disable all serial ports. 3818 3819 Available character devices are: 3820 3821 ``vc[:WxH]`` 3822 Virtual console. Optionally, a width and height can be given in 3823 pixel with 3824 3825 :: 3826 3827 vc:800x600 3828 3829 It is also possible to specify width or height in characters: 3830 3831 :: 3832 3833 vc:80Cx24C 3834 3835 ``pty`` 3836 [Linux only] Pseudo TTY (a new PTY is automatically allocated) 3837 3838 ``none`` 3839 No device is allocated. 3840 3841 ``null`` 3842 void device 3843 3844 ``chardev:id`` 3845 Use a named character device defined with the ``-chardev`` 3846 option. 3847 3848 ``/dev/XXX`` 3849 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial 3850 port parameters are set according to the emulated ones. 3851 3852 ``/dev/parportN`` 3853 [Linux only, parallel port only] Use host parallel port N. 3854 Currently SPP and EPP parallel port features can be used. 3855 3856 ``file:filename`` 3857 Write output to filename. No character can be read. 3858 3859 ``stdio`` 3860 [Unix only] standard input/output 3861 3862 ``pipe:filename`` 3863 name pipe filename 3864 3865 ``COMn`` 3866 [Windows only] Use host serial port n 3867 3868 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]`` 3869 This implements UDP Net Console. When remote\_host or src\_ip 3870 are not specified they default to ``0.0.0.0``. When not using a 3871 specified src\_port a random port is automatically chosen. 3872 3873 If you just want a simple readonly console you can use 3874 ``netcat`` or ``nc``, by starting QEMU with: 3875 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time 3876 QEMU writes something to that port it will appear in the 3877 netconsole session. 3878 3879 If you plan to send characters back via netconsole or you want 3880 to stop and start QEMU a lot of times, you should have QEMU use 3881 the same source port each time by using something like ``-serial 3882 udp::4555@:4556`` to QEMU. Another approach is to use a patched 3883 version of netcat which can listen to a TCP port and send and 3884 receive characters via udp. If you have a patched version of 3885 netcat which activates telnet remote echo and single char 3886 transfer, then you can use the following options to set up a 3887 netcat redirector to allow telnet on port 5555 to access the 3888 QEMU port. 3889 3890 ``QEMU Options:`` 3891 -serial udp::4555@:4556 3892 3893 ``netcat options:`` 3894 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T 3895 3896 ``telnet options:`` 3897 localhost 5555 3898 3899 ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]`` 3900 The TCP Net Console has two modes of operation. It can send the 3901 serial I/O to a location or wait for a connection from a 3902 location. By default the TCP Net Console is sent to host at the 3903 port. If you use the ``server=on`` option QEMU will wait for a client 3904 socket application to connect to the port before continuing, 3905 unless the ``wait=on|off`` option was specified. The ``nodelay=on|off`` 3906 option disables the Nagle buffering algorithm. The ``reconnect=on`` 3907 option only applies if ``server=no`` is set, if the connection goes 3908 down it will attempt to reconnect at the given interval. If host 3909 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a 3910 time is accepted. You can use ``telnet=on`` to connect to the 3911 corresponding character device. 3912 3913 ``Example to send tcp console to 192.168.0.2 port 4444`` 3914 -serial tcp:192.168.0.2:4444 3915 3916 ``Example to listen and wait on port 4444 for connection`` 3917 -serial tcp::4444,server=on 3918 3919 ``Example to not wait and listen on ip 192.168.0.100 port 4444`` 3920 -serial tcp:192.168.0.100:4444,server=on,wait=off 3921 3922 ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]`` 3923 The telnet protocol is used instead of raw tcp sockets. The 3924 options work the same as if you had specified ``-serial tcp``. 3925 The difference is that the port acts like a telnet server or 3926 client using telnet option negotiation. This will also allow you 3927 to send the MAGIC\_SYSRQ sequence if you use a telnet that 3928 supports sending the break sequence. Typically in unix telnet 3929 you do it with Control-] and then type "send break" followed by 3930 pressing the enter key. 3931 3932 ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]`` 3933 The WebSocket protocol is used instead of raw tcp socket. The 3934 port acts as a WebSocket server. Client mode is not supported. 3935 3936 ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]`` 3937 A unix domain socket is used instead of a tcp socket. The option 3938 works the same as if you had specified ``-serial tcp`` except 3939 the unix domain socket path is used for connections. 3940 3941 ``mon:dev_string`` 3942 This is a special option to allow the monitor to be multiplexed 3943 onto another serial port. The monitor is accessed with key 3944 sequence of Control-a and then pressing c. dev\_string should be 3945 any one of the serial devices specified above. An example to 3946 multiplex the monitor onto a telnet server listening on port 3947 4444 would be: 3948 3949 ``-serial mon:telnet::4444,server=on,wait=off`` 3950 3951 When the monitor is multiplexed to stdio in this way, Ctrl+C 3952 will not terminate QEMU any more but will be passed to the guest 3953 instead. 3954 3955 ``braille`` 3956 Braille device. This will use BrlAPI to display the braille 3957 output on a real or fake device. 3958 3959 ``msmouse`` 3960 Three button serial mouse. Configure the guest to use Microsoft 3961 protocol. 3962ERST 3963 3964DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \ 3965 "-parallel dev redirect the parallel port to char device 'dev'\n", 3966 QEMU_ARCH_ALL) 3967SRST 3968``-parallel dev`` 3969 Redirect the virtual parallel port to host device dev (same devices 3970 as the serial port). On Linux hosts, ``/dev/parportN`` can be used 3971 to use hardware devices connected on the corresponding host parallel 3972 port. 3973 3974 This option can be used several times to simulate up to 3 parallel 3975 ports. 3976 3977 Use ``-parallel none`` to disable all parallel ports. 3978ERST 3979 3980DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \ 3981 "-monitor dev redirect the monitor to char device 'dev'\n", 3982 QEMU_ARCH_ALL) 3983SRST 3984``-monitor dev`` 3985 Redirect the monitor to host device dev (same devices as the serial 3986 port). The default device is ``vc`` in graphical mode and ``stdio`` 3987 in non graphical mode. Use ``-monitor none`` to disable the default 3988 monitor. 3989ERST 3990DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \ 3991 "-qmp dev like -monitor but opens in 'control' mode\n", 3992 QEMU_ARCH_ALL) 3993SRST 3994``-qmp dev`` 3995 Like -monitor but opens in 'control' mode. 3996ERST 3997DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \ 3998 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n", 3999 QEMU_ARCH_ALL) 4000SRST 4001``-qmp-pretty dev`` 4002 Like -qmp but uses pretty JSON formatting. 4003ERST 4004 4005DEF("mon", HAS_ARG, QEMU_OPTION_mon, \ 4006 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL) 4007SRST 4008``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]`` 4009 Setup monitor on chardev name. ``mode=control`` configures 4010 a QMP monitor (a JSON RPC-style protocol) and it is not the 4011 same as HMP, the human monitor that has a "(qemu)" prompt. 4012 ``pretty`` is only valid when ``mode=control``, 4013 turning on JSON pretty printing to ease 4014 human reading and debugging. 4015ERST 4016 4017DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \ 4018 "-debugcon dev redirect the debug console to char device 'dev'\n", 4019 QEMU_ARCH_ALL) 4020SRST 4021``-debugcon dev`` 4022 Redirect the debug console to host device dev (same devices as the 4023 serial port). The debug console is an I/O port which is typically 4024 port 0xe9; writing to that I/O port sends output to this device. The 4025 default device is ``vc`` in graphical mode and ``stdio`` in non 4026 graphical mode. 4027ERST 4028 4029DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \ 4030 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL) 4031SRST 4032``-pidfile file`` 4033 Store the QEMU process PID in file. It is useful if you launch QEMU 4034 from a script. 4035ERST 4036 4037DEF("singlestep", 0, QEMU_OPTION_singlestep, \ 4038 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL) 4039SRST 4040``-singlestep`` 4041 Run the emulation in single step mode. 4042ERST 4043 4044DEF("preconfig", 0, QEMU_OPTION_preconfig, \ 4045 "--preconfig pause QEMU before machine is initialized (experimental)\n", 4046 QEMU_ARCH_ALL) 4047SRST 4048``--preconfig`` 4049 Pause QEMU for interactive configuration before the machine is 4050 created, which allows querying and configuring properties that will 4051 affect machine initialization. Use QMP command 'x-exit-preconfig' to 4052 exit the preconfig state and move to the next state (i.e. run guest 4053 if -S isn't used or pause the second time if -S is used). This 4054 option is experimental. 4055ERST 4056 4057DEF("S", 0, QEMU_OPTION_S, \ 4058 "-S freeze CPU at startup (use 'c' to start execution)\n", 4059 QEMU_ARCH_ALL) 4060SRST 4061``-S`` 4062 Do not start CPU at startup (you must type 'c' in the monitor). 4063ERST 4064 4065DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit, 4066 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n" 4067 " run qemu with overcommit hints\n" 4068 " mem-lock=on|off controls memory lock support (default: off)\n" 4069 " cpu-pm=on|off controls cpu power management (default: off)\n", 4070 QEMU_ARCH_ALL) 4071SRST 4072``-overcommit mem-lock=on|off`` 4073 \ 4074``-overcommit cpu-pm=on|off`` 4075 Run qemu with hints about host resource overcommit. The default is 4076 to assume that host overcommits all resources. 4077 4078 Locking qemu and guest memory can be enabled via ``mem-lock=on`` 4079 (disabled by default). This works when host memory is not 4080 overcommitted and reduces the worst-case latency for guest. 4081 4082 Guest ability to manage power state of host cpus (increasing latency 4083 for other processes on the same host cpu, but decreasing latency for 4084 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This 4085 works best when host CPU is not overcommitted. When used, host 4086 estimates of CPU cycle and power utilization will be incorrect, not 4087 taking into account guest idle time. 4088ERST 4089 4090DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \ 4091 "-gdb dev accept gdb connection on 'dev'. (QEMU defaults to starting\n" 4092 " the guest without waiting for gdb to connect; use -S too\n" 4093 " if you want it to not start execution.)\n", 4094 QEMU_ARCH_ALL) 4095SRST 4096``-gdb dev`` 4097 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter 4098 in the System Emulation Users Guide). Note that this option does not pause QEMU 4099 execution -- if you want QEMU to not start the guest until you 4100 connect with gdb and issue a ``continue`` command, you will need to 4101 also pass the ``-S`` option to QEMU. 4102 4103 The most usual configuration is to listen on a local TCP socket:: 4104 4105 -gdb tcp::3117 4106 4107 but you can specify other backends; UDP, pseudo TTY, or even stdio 4108 are all reasonable use cases. For example, a stdio connection 4109 allows you to start QEMU from within gdb and establish the 4110 connection via a pipe: 4111 4112 .. parsed-literal:: 4113 4114 (gdb) target remote | exec |qemu_system| -gdb stdio ... 4115ERST 4116 4117DEF("s", 0, QEMU_OPTION_s, \ 4118 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n", 4119 QEMU_ARCH_ALL) 4120SRST 4121``-s`` 4122 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234 4123 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide). 4124ERST 4125 4126DEF("d", HAS_ARG, QEMU_OPTION_d, \ 4127 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n", 4128 QEMU_ARCH_ALL) 4129SRST 4130``-d item1[,...]`` 4131 Enable logging of specified items. Use '-d help' for a list of log 4132 items. 4133ERST 4134 4135DEF("D", HAS_ARG, QEMU_OPTION_D, \ 4136 "-D logfile output log to logfile (default stderr)\n", 4137 QEMU_ARCH_ALL) 4138SRST 4139``-D logfile`` 4140 Output log in logfile instead of to stderr 4141ERST 4142 4143DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \ 4144 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n", 4145 QEMU_ARCH_ALL) 4146SRST 4147``-dfilter range1[,...]`` 4148 Filter debug output to that relevant to a range of target addresses. 4149 The filter spec can be either start+size, start-size or start..end 4150 where start end and size are the addresses and sizes required. For 4151 example: 4152 4153 :: 4154 4155 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000 4156 4157 Will dump output for any code in the 0x1000 sized block starting at 4158 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and 4159 another 0x1000 sized block starting at 0xffffffc00005f000. 4160ERST 4161 4162DEF("seed", HAS_ARG, QEMU_OPTION_seed, \ 4163 "-seed number seed the pseudo-random number generator\n", 4164 QEMU_ARCH_ALL) 4165SRST 4166``-seed number`` 4167 Force the guest to use a deterministic pseudo-random number 4168 generator, seeded with number. This does not affect crypto routines 4169 within the host. 4170ERST 4171 4172DEF("L", HAS_ARG, QEMU_OPTION_L, \ 4173 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n", 4174 QEMU_ARCH_ALL) 4175SRST 4176``-L path`` 4177 Set the directory for the BIOS, VGA BIOS and keymaps. 4178 4179 To list all the data directories, use ``-L help``. 4180ERST 4181 4182DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ 4183 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) 4184SRST 4185``-bios file`` 4186 Set the filename for the BIOS. 4187ERST 4188 4189DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ 4190 "-enable-kvm enable KVM full virtualization support\n", 4191 QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC | 4192 QEMU_ARCH_RISCV | QEMU_ARCH_S390X) 4193SRST 4194``-enable-kvm`` 4195 Enable KVM full virtualization support. This option is only 4196 available if KVM support is enabled when compiling. 4197ERST 4198 4199DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid, 4200 "-xen-domid id specify xen guest domain id\n", 4201 QEMU_ARCH_ARM | QEMU_ARCH_I386) 4202DEF("xen-attach", 0, QEMU_OPTION_xen_attach, 4203 "-xen-attach attach to existing xen domain\n" 4204 " libxl will use this when starting QEMU\n", 4205 QEMU_ARCH_ARM | QEMU_ARCH_I386) 4206DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict, 4207 "-xen-domid-restrict restrict set of available xen operations\n" 4208 " to specified domain id. (Does not affect\n" 4209 " xenpv machine type).\n", 4210 QEMU_ARCH_ARM | QEMU_ARCH_I386) 4211SRST 4212``-xen-domid id`` 4213 Specify xen guest domain id (XEN only). 4214 4215``-xen-attach`` 4216 Attach to existing xen domain. libxl will use this when starting 4217 QEMU (XEN only). Restrict set of available xen operations to 4218 specified domain id (XEN only). 4219ERST 4220 4221DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \ 4222 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL) 4223SRST 4224``-no-reboot`` 4225 Exit instead of rebooting. 4226ERST 4227 4228DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \ 4229 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL) 4230SRST 4231``-no-shutdown`` 4232 Don't exit QEMU on guest shutdown, but instead only stop the 4233 emulation. This allows for instance switching to monitor to commit 4234 changes to the disk image. 4235ERST 4236 4237DEF("action", HAS_ARG, QEMU_OPTION_action, 4238 "-action reboot=reset|shutdown\n" 4239 " action when guest reboots [default=reset]\n" 4240 "-action shutdown=poweroff|pause\n" 4241 " action when guest shuts down [default=poweroff]\n" 4242 "-action panic=pause|shutdown|none\n" 4243 " action when guest panics [default=shutdown]\n" 4244 "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" 4245 " action when watchdog fires [default=reset]\n", 4246 QEMU_ARCH_ALL) 4247SRST 4248``-action event=action`` 4249 The action parameter serves to modify QEMU's default behavior when 4250 certain guest events occur. It provides a generic method for specifying the 4251 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown`` 4252 parameters. 4253 4254 Examples: 4255 4256 ``-action panic=none`` 4257 ``-action reboot=shutdown,shutdown=pause`` 4258 ``-watchdog i6300esb -action watchdog=pause`` 4259 4260ERST 4261 4262DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \ 4263 "-loadvm [tag|id]\n" \ 4264 " start right away with a saved state (loadvm in monitor)\n", 4265 QEMU_ARCH_ALL) 4266SRST 4267``-loadvm file`` 4268 Start right away with a saved state (``loadvm`` in monitor) 4269ERST 4270 4271#ifndef _WIN32 4272DEF("daemonize", 0, QEMU_OPTION_daemonize, \ 4273 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL) 4274#endif 4275SRST 4276``-daemonize`` 4277 Daemonize the QEMU process after initialization. QEMU will not 4278 detach from standard IO until it is ready to receive connections on 4279 any of its devices. This option is a useful way for external 4280 programs to launch QEMU without having to cope with initialization 4281 race conditions. 4282ERST 4283 4284DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \ 4285 "-option-rom rom load a file, rom, into the option ROM space\n", 4286 QEMU_ARCH_ALL) 4287SRST 4288``-option-rom file`` 4289 Load the contents of file as an option ROM. This option is useful to 4290 load things like EtherBoot. 4291ERST 4292 4293DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \ 4294 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \ 4295 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n", 4296 QEMU_ARCH_ALL) 4297 4298SRST 4299``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]`` 4300 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at 4301 the current UTC or local time, respectively. ``localtime`` is 4302 required for correct date in MS-DOS or Windows. To start at a 4303 specific point in time, provide datetime in the format 4304 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC. 4305 4306 By default the RTC is driven by the host system time. This allows 4307 using of the RTC as accurate reference clock inside the guest, 4308 specifically if the host time is smoothly following an accurate 4309 external reference clock, e.g. via NTP. If you want to isolate the 4310 guest time from the host, you can set ``clock`` to ``rt`` instead, 4311 which provides a host monotonic clock if host support it. To even 4312 prevent the RTC from progressing during suspension, you can set 4313 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is 4314 recommended especially in icount mode in order to preserve 4315 determinism; however, note that in icount mode the speed of the 4316 virtual clock is variable and can in general differ from the host 4317 clock. 4318 4319 Enable ``driftfix`` (i386 targets only) if you experience time drift 4320 problems, specifically with Windows' ACPI HAL. This option will try 4321 to figure out how many timer interrupts were not processed by the 4322 Windows guest and will re-inject them. 4323ERST 4324 4325DEF("icount", HAS_ARG, QEMU_OPTION_icount, \ 4326 "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \ 4327 " enable virtual instruction counter with 2^N clock ticks per\n" \ 4328 " instruction, enable aligning the host and virtual clocks\n" \ 4329 " or disable real time cpu sleeping, and optionally enable\n" \ 4330 " record-and-replay mode\n", QEMU_ARCH_ALL) 4331SRST 4332``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]`` 4333 Enable virtual instruction counter. The virtual cpu will execute one 4334 instruction every 2^N ns of virtual time. If ``auto`` is specified 4335 then the virtual cpu speed will be automatically adjusted to keep 4336 virtual time within a few seconds of real time. 4337 4338 Note that while this option can give deterministic behavior, it does 4339 not provide cycle accurate emulation. Modern CPUs contain 4340 superscalar out of order cores with complex cache hierarchies. The 4341 number of instructions executed often has little or no correlation 4342 with actual performance. 4343 4344 When the virtual cpu is sleeping, the virtual time will advance at 4345 default speed unless ``sleep=on`` is specified. With 4346 ``sleep=on``, the virtual time will jump to the next timer 4347 deadline instantly whenever the virtual cpu goes to sleep mode and 4348 will not advance if no timer is enabled. This behavior gives 4349 deterministic execution times from the guest point of view. 4350 The default if icount is enabled is ``sleep=off``. 4351 ``sleep=on`` cannot be used together with either ``shift=auto`` 4352 or ``align=on``. 4353 4354 ``align=on`` will activate the delay algorithm which will try to 4355 synchronise the host clock and the virtual clock. The goal is to 4356 have a guest running at the real frequency imposed by the shift 4357 option. Whenever the guest clock is behind the host clock and if 4358 ``align=on`` is specified then we print a message to the user to 4359 inform about the delay. Currently this option does not work when 4360 ``shift`` is ``auto``. Note: The sync algorithm will work for those 4361 shift values for which the guest clock runs ahead of the host clock. 4362 Typically this happens when the shift value is high (how high 4363 depends on the host machine). The default if icount is enabled 4364 is ``align=off``. 4365 4366 When the ``rr`` option is specified deterministic record/replay is 4367 enabled. The ``rrfile=`` option must also be provided to 4368 specify the path to the replay log. In record mode data is written 4369 to this file, and in replay mode it is read back. 4370 If the ``rrsnapshot`` option is given then it specifies a VM snapshot 4371 name. In record mode, a new VM snapshot with the given name is created 4372 at the start of execution recording. In replay mode this option 4373 specifies the snapshot name used to load the initial VM state. 4374ERST 4375 4376DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \ 4377 "-watchdog model\n" \ 4378 " enable virtual hardware watchdog [default=none]\n", 4379 QEMU_ARCH_ALL) 4380SRST 4381``-watchdog model`` 4382 Create a virtual hardware watchdog device. Once enabled (by a guest 4383 action), the watchdog must be periodically polled by an agent inside 4384 the guest or else the guest will be restarted. Choose a model for 4385 which your guest has drivers. 4386 4387 The model is the model of hardware watchdog to emulate. Use 4388 ``-watchdog help`` to list available hardware models. Only one 4389 watchdog can be enabled for a guest. 4390 4391 The following models may be available: 4392 4393 ``ib700`` 4394 iBASE 700 is a very simple ISA watchdog with a single timer. 4395 4396 ``i6300esb`` 4397 Intel 6300ESB I/O controller hub is a much more featureful 4398 PCI-based dual-timer watchdog. 4399 4400 ``diag288`` 4401 A virtual watchdog for s390x backed by the diagnose 288 4402 hypercall (currently KVM only). 4403ERST 4404 4405DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \ 4406 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \ 4407 " action when watchdog fires [default=reset]\n", 4408 QEMU_ARCH_ALL) 4409SRST 4410``-watchdog-action action`` 4411 The action controls what QEMU will do when the watchdog timer 4412 expires. The default is ``reset`` (forcefully reset the guest). 4413 Other possible actions are: ``shutdown`` (attempt to gracefully 4414 shutdown the guest), ``poweroff`` (forcefully poweroff the guest), 4415 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the 4416 guest), ``debug`` (print a debug message and continue), or ``none`` 4417 (do nothing). 4418 4419 Note that the ``shutdown`` action requires that the guest responds 4420 to ACPI signals, which it may not be able to do in the sort of 4421 situations where the watchdog would have expired, and thus 4422 ``-watchdog-action shutdown`` is not recommended for production use. 4423 4424 Examples: 4425 4426 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700`` 4427 4428ERST 4429 4430DEF("echr", HAS_ARG, QEMU_OPTION_echr, \ 4431 "-echr chr set terminal escape character instead of ctrl-a\n", 4432 QEMU_ARCH_ALL) 4433SRST 4434``-echr numeric_ascii_value`` 4435 Change the escape character used for switching to the monitor when 4436 using monitor and serial sharing. The default is ``0x01`` when using 4437 the ``-nographic`` option. ``0x01`` is equal to pressing 4438 ``Control-a``. You can select a different character from the ascii 4439 control keys where 1 through 26 map to Control-a through Control-z. 4440 For instance you could use the either of the following to change the 4441 escape character to Control-t. 4442 4443 ``-echr 0x14``; \ ``-echr 20`` 4444 4445ERST 4446 4447DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \ 4448 "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \ 4449 "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \ 4450 "-incoming unix:socketpath\n" \ 4451 " prepare for incoming migration, listen on\n" \ 4452 " specified protocol and socket address\n" \ 4453 "-incoming fd:fd\n" \ 4454 "-incoming exec:cmdline\n" \ 4455 " accept incoming migration on given file descriptor\n" \ 4456 " or from given external command\n" \ 4457 "-incoming defer\n" \ 4458 " wait for the URI to be specified via migrate_incoming\n", 4459 QEMU_ARCH_ALL) 4460SRST 4461``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]`` 4462 \ 4463``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]`` 4464 Prepare for incoming migration, listen on a given tcp port. 4465 4466``-incoming unix:socketpath`` 4467 Prepare for incoming migration, listen on a given unix socket. 4468 4469``-incoming fd:fd`` 4470 Accept incoming migration from a given filedescriptor. 4471 4472``-incoming exec:cmdline`` 4473 Accept incoming migration as an output from specified external 4474 command. 4475 4476``-incoming defer`` 4477 Wait for the URI to be specified via migrate\_incoming. The monitor 4478 can be used to change settings (such as migration parameters) prior 4479 to issuing the migrate\_incoming to allow the migration to begin. 4480ERST 4481 4482DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \ 4483 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL) 4484SRST 4485``-only-migratable`` 4486 Only allow migratable devices. Devices will not be allowed to enter 4487 an unmigratable state. 4488ERST 4489 4490DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \ 4491 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL) 4492SRST 4493``-nodefaults`` 4494 Don't create default devices. Normally, QEMU sets the default 4495 devices like serial port, parallel port, virtual console, monitor 4496 device, VGA adapter, floppy and CD-ROM drive and others. The 4497 ``-nodefaults`` option will disable all those default devices. 4498ERST 4499 4500#ifndef _WIN32 4501DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \ 4502 "-chroot dir chroot to dir just before starting the VM\n", 4503 QEMU_ARCH_ALL) 4504#endif 4505SRST 4506``-chroot dir`` 4507 Immediately before starting guest execution, chroot to the specified 4508 directory. Especially useful in combination with -runas. 4509ERST 4510 4511#ifndef _WIN32 4512DEF("runas", HAS_ARG, QEMU_OPTION_runas, \ 4513 "-runas user change to user id user just before starting the VM\n" \ 4514 " user can be numeric uid:gid instead\n", 4515 QEMU_ARCH_ALL) 4516#endif 4517SRST 4518``-runas user`` 4519 Immediately before starting guest execution, drop root privileges, 4520 switching to the specified user. 4521ERST 4522 4523DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env, 4524 "-prom-env variable=value\n" 4525 " set OpenBIOS nvram variables\n", 4526 QEMU_ARCH_PPC | QEMU_ARCH_SPARC) 4527SRST 4528``-prom-env variable=value`` 4529 Set OpenBIOS nvram variable to given value (PPC, SPARC only). 4530 4531 :: 4532 4533 qemu-system-sparc -prom-env 'auto-boot?=false' \ 4534 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single' 4535 4536 :: 4537 4538 qemu-system-ppc -prom-env 'auto-boot?=false' \ 4539 -prom-env 'boot-device=hd:2,\yaboot' \ 4540 -prom-env 'boot-args=conf=hd:2,\yaboot.conf' 4541ERST 4542DEF("semihosting", 0, QEMU_OPTION_semihosting, 4543 "-semihosting semihosting mode\n", 4544 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4545 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4546SRST 4547``-semihosting`` 4548 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V 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 See the -semihosting-config option documentation for further 4554 information about the facilities this enables. 4555ERST 4556DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, 4557 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \ 4558 " semihosting configuration\n", 4559QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4560QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4561SRST 4562``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]`` 4563 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V 4564 only). 4565 4566 Note that this allows guest direct access to the host filesystem, so 4567 should only be used with a trusted guest OS. 4568 4569 On Arm this implements the standard semihosting API, version 2.0. 4570 4571 On M68K this implements the "ColdFire GDB" interface used by 4572 libgloss. 4573 4574 Xtensa semihosting provides basic file IO calls, such as 4575 open/read/write/seek/select. Tensilica baremetal libc for ISS and 4576 linux platform "sim" use this interface. 4577 4578 On RISC-V this implements the standard semihosting API, version 0.2. 4579 4580 ``target=native|gdb|auto`` 4581 Defines where the semihosting calls will be addressed, to QEMU 4582 (``native``) or to GDB (``gdb``). The default is ``auto``, which 4583 means ``gdb`` during debug sessions and ``native`` otherwise. 4584 4585 ``chardev=str1`` 4586 Send the output to a chardev backend output for native or auto 4587 output when not in gdb 4588 4589 ``arg=str1,arg=str2,...`` 4590 Allows the user to pass input arguments, and can be used 4591 multiple times to build up a list. The old-style 4592 ``-kernel``/``-append`` method of passing a command line is 4593 still supported for backward compatibility. If both the 4594 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are 4595 specified, the former is passed to semihosting as it always 4596 takes precedence. 4597ERST 4598DEF("old-param", 0, QEMU_OPTION_old_param, 4599 "-old-param old param mode\n", QEMU_ARCH_ARM) 4600SRST 4601``-old-param`` 4602 Old param mode (ARM only). 4603ERST 4604 4605DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ 4606 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ 4607 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \ 4608 " Enable seccomp mode 2 system call filter (default 'off').\n" \ 4609 " use 'obsolete' to allow obsolete system calls that are provided\n" \ 4610 " by the kernel, but typically no longer used by modern\n" \ 4611 " C library implementations.\n" \ 4612 " use 'elevateprivileges' to allow or deny the QEMU process ability\n" \ 4613 " to elevate privileges using set*uid|gid system calls.\n" \ 4614 " The value 'children' will deny set*uid|gid system calls for\n" \ 4615 " main QEMU process but will allow forks and execves to run unprivileged\n" \ 4616 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \ 4617 " blocking *fork and execve\n" \ 4618 " use 'resourcecontrol' to disable process affinity and schedular priority\n", 4619 QEMU_ARCH_ALL) 4620SRST 4621``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]`` 4622 Enable Seccomp mode 2 system call filter. 'on' will enable syscall 4623 filtering and 'off' will disable it. The default is 'off'. 4624 4625 ``obsolete=string`` 4626 Enable Obsolete system calls 4627 4628 ``elevateprivileges=string`` 4629 Disable set\*uid\|gid system calls 4630 4631 ``spawn=string`` 4632 Disable \*fork and execve 4633 4634 ``resourcecontrol=string`` 4635 Disable process affinity and schedular priority 4636ERST 4637 4638DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig, 4639 "-readconfig <file>\n" 4640 " read config file\n", QEMU_ARCH_ALL) 4641SRST 4642``-readconfig file`` 4643 Read device configuration from file. This approach is useful when 4644 you want to spawn QEMU process with many command line options but 4645 you don't want to exceed the command line character limit. 4646ERST 4647 4648DEF("no-user-config", 0, QEMU_OPTION_nouserconfig, 4649 "-no-user-config\n" 4650 " do not load default user-provided config files at startup\n", 4651 QEMU_ARCH_ALL) 4652SRST 4653``-no-user-config`` 4654 The ``-no-user-config`` option makes QEMU not load any of the 4655 user-provided config files on sysconfdir. 4656ERST 4657 4658DEF("trace", HAS_ARG, QEMU_OPTION_trace, 4659 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n" 4660 " specify tracing options\n", 4661 QEMU_ARCH_ALL) 4662SRST 4663``-trace [[enable=]pattern][,events=file][,file=file]`` 4664 .. include:: ../qemu-option-trace.rst.inc 4665 4666ERST 4667DEF("plugin", HAS_ARG, QEMU_OPTION_plugin, 4668 "-plugin [file=]<file>[,<argname>=<argvalue>]\n" 4669 " load a plugin\n", 4670 QEMU_ARCH_ALL) 4671SRST 4672``-plugin file=file[,argname=argvalue]`` 4673 Load a plugin. 4674 4675 ``file=file`` 4676 Load the given plugin from a shared library file. 4677 4678 ``argname=argvalue`` 4679 Argument passed to the plugin. (Can be given multiple times.) 4680ERST 4681 4682HXCOMM Internal use 4683DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL) 4684DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL) 4685 4686DEF("msg", HAS_ARG, QEMU_OPTION_msg, 4687 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n" 4688 " control error message format\n" 4689 " timestamp=on enables timestamps (default: off)\n" 4690 " guest-name=on enables guest name prefix but only if\n" 4691 " -name guest option is set (default: off)\n", 4692 QEMU_ARCH_ALL) 4693SRST 4694``-msg [timestamp[=on|off]][,guest-name[=on|off]]`` 4695 Control error message format. 4696 4697 ``timestamp=on|off`` 4698 Prefix messages with a timestamp. Default is off. 4699 4700 ``guest-name=on|off`` 4701 Prefix messages with guest name but only if -name guest option is set 4702 otherwise the option is ignored. Default is off. 4703ERST 4704 4705DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate, 4706 "-dump-vmstate <file>\n" 4707 " Output vmstate information in JSON format to file.\n" 4708 " Use the scripts/vmstate-static-checker.py file to\n" 4709 " check for possible regressions in migration code\n" 4710 " by comparing two such vmstate dumps.\n", 4711 QEMU_ARCH_ALL) 4712SRST 4713``-dump-vmstate file`` 4714 Dump json-encoded vmstate information for current machine type to 4715 file in file 4716ERST 4717 4718DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile, 4719 "-enable-sync-profile\n" 4720 " enable synchronization profiling\n", 4721 QEMU_ARCH_ALL) 4722SRST 4723``-enable-sync-profile`` 4724 Enable synchronization profiling. 4725ERST 4726 4727DEFHEADING() 4728 4729DEFHEADING(Generic object creation:) 4730 4731DEF("object", HAS_ARG, QEMU_OPTION_object, 4732 "-object TYPENAME[,PROP1=VALUE1,...]\n" 4733 " create a new object of type TYPENAME setting properties\n" 4734 " in the order they are specified. Note that the 'id'\n" 4735 " property must be set. These objects are placed in the\n" 4736 " '/objects' path.\n", 4737 QEMU_ARCH_ALL) 4738SRST 4739``-object typename[,prop1=value1,...]`` 4740 Create a new object of type typename setting properties in the order 4741 they are specified. Note that the 'id' property must be set. These 4742 objects are placed in the '/objects' path. 4743 4744 ``-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`` 4745 Creates a memory file backend object, which can be used to back 4746 the guest RAM with huge pages. 4747 4748 The ``id`` parameter is a unique ID that will be used to 4749 reference this memory region in other parameters, e.g. ``-numa``, 4750 ``-device nvdimm``, etc. 4751 4752 The ``size`` option provides the size of the memory region, and 4753 accepts common suffixes, e.g. ``500M``. 4754 4755 The ``mem-path`` provides the path to either a shared memory or 4756 huge page filesystem mount. 4757 4758 The ``share`` boolean option determines whether the memory 4759 region is marked as private to QEMU, or shared. The latter 4760 allows a co-operating external process to access the QEMU memory 4761 region. 4762 4763 The ``share`` is also required for pvrdma devices due to 4764 limitations in the RDMA API provided by Linux. 4765 4766 Setting share=on might affect the ability to configure NUMA 4767 bindings for the memory backend under some circumstances, see 4768 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel 4769 source tree for additional details. 4770 4771 Setting the ``discard-data`` boolean option to on indicates that 4772 file contents can be destroyed when QEMU exits, to avoid 4773 unnecessarily flushing data to the backing file. Note that 4774 ``discard-data`` is only an optimization, and QEMU might not 4775 discard file contents if it aborts unexpectedly or is terminated 4776 using SIGKILL. 4777 4778 The ``merge`` boolean option enables memory merge, also known as 4779 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider 4780 the pages for memory deduplication. 4781 4782 Setting the ``dump`` boolean option to off excludes the memory 4783 from core dumps. This feature is also known as MADV\_DONTDUMP. 4784 4785 The ``prealloc`` boolean option enables memory preallocation. 4786 4787 The ``host-nodes`` option binds the memory range to a list of 4788 NUMA host nodes. 4789 4790 The ``policy`` option sets the NUMA policy to one of the 4791 following values: 4792 4793 ``default`` 4794 default host policy 4795 4796 ``preferred`` 4797 prefer the given host node list for allocation 4798 4799 ``bind`` 4800 restrict memory allocation to the given host node list 4801 4802 ``interleave`` 4803 interleave memory allocations across the given host node 4804 list 4805 4806 The ``align`` option specifies the base address alignment when 4807 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg 4808 ``2M``. Some backend store specified by ``mem-path`` requires an 4809 alignment different than the default one used by QEMU, eg the 4810 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In 4811 such cases, users can specify the required alignment via this 4812 option. 4813 4814 The ``pmem`` option specifies whether the backing file specified 4815 by ``mem-path`` is in host persistent memory that can be 4816 accessed using the SNIA NVM programming model (e.g. Intel 4817 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary 4818 operations to guarantee the persistence of its own writes to 4819 ``mem-path`` (e.g. in vNVDIMM label emulation and live 4820 migration). Also, we will map the backend-file with MAP\_SYNC 4821 flag, which ensures the file metadata is in sync for 4822 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC 4823 requires support from both the host kernel (since Linux kernel 4824 4.15) and the filesystem of ``mem-path`` mounted with DAX 4825 option. 4826 4827 The ``readonly`` option specifies whether the backing file is opened 4828 read-only or read-write (default). 4829 4830 ``-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`` 4831 Creates a memory backend object, which can be used to back the 4832 guest RAM. Memory backend objects offer more control than the 4833 ``-m`` option that is traditionally used to define guest RAM. 4834 Please refer to ``memory-backend-file`` for a description of the 4835 options. 4836 4837 ``-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`` 4838 Creates an anonymous memory file backend object, which allows 4839 QEMU to share the memory with an external process (e.g. when 4840 using vhost-user). The memory is allocated with memfd and 4841 optional sealing. (Linux only) 4842 4843 The ``seal`` option creates a sealed-file, that will block 4844 further resizing the memory ('on' by default). 4845 4846 The ``hugetlb`` option specify the file to be created resides in 4847 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction 4848 with the ``hugetlb`` option, the ``hugetlbsize`` option specify 4849 the hugetlb page size on systems that support multiple hugetlb 4850 page sizes (it must be a power of 2 value supported by the 4851 system). 4852 4853 In some versions of Linux, the ``hugetlb`` option is 4854 incompatible with the ``seal`` option (requires at least Linux 4855 4.16). 4856 4857 Please refer to ``memory-backend-file`` for a description of the 4858 other options. 4859 4860 The ``share`` boolean option is on by default with memfd. 4861 4862 ``-object rng-builtin,id=id`` 4863 Creates a random number generator backend which obtains entropy 4864 from QEMU builtin functions. The ``id`` parameter is a unique ID 4865 that will be used to reference this entropy backend from the 4866 ``virtio-rng`` device. By default, the ``virtio-rng`` device 4867 uses this RNG backend. 4868 4869 ``-object rng-random,id=id,filename=/dev/random`` 4870 Creates a random number generator backend which obtains entropy 4871 from a device on the host. The ``id`` parameter is a unique ID 4872 that will be used to reference this entropy backend from the 4873 ``virtio-rng`` device. The ``filename`` parameter specifies 4874 which file to obtain entropy from and if omitted defaults to 4875 ``/dev/urandom``. 4876 4877 ``-object rng-egd,id=id,chardev=chardevid`` 4878 Creates a random number generator backend which obtains entropy 4879 from an external daemon running on the host. The ``id`` 4880 parameter is a unique ID that will be used to reference this 4881 entropy backend from the ``virtio-rng`` device. The ``chardev`` 4882 parameter is the unique ID of a character device backend that 4883 provides the connection to the RNG daemon. 4884 4885 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off`` 4886 Creates a TLS anonymous credentials object, which can be used to 4887 provide TLS support on network backends. The ``id`` parameter is 4888 a unique ID which network backends will use to access the 4889 credentials. The ``endpoint`` is either ``server`` or ``client`` 4890 depending on whether the QEMU network backend that uses the 4891 credentials will be acting as a client or as a server. If 4892 ``verify-peer`` is enabled (the default) then once the handshake 4893 is completed, the peer credentials will be verified, though this 4894 is a no-op for anonymous credentials. 4895 4896 The dir parameter tells QEMU where to find the credential files. 4897 For server endpoints, this directory may contain a file 4898 dh-params.pem providing diffie-hellman parameters to use for the 4899 TLS server. If the file is missing, QEMU will generate a set of 4900 DH parameters at startup. This is a computationally expensive 4901 operation that consumes random pool entropy, so it is 4902 recommended that a persistent set of parameters be generated 4903 upfront and saved. 4904 4905 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]`` 4906 Creates a TLS Pre-Shared Keys (PSK) credentials object, which 4907 can be used to provide TLS support on network backends. The 4908 ``id`` parameter is a unique ID which network backends will use 4909 to access the credentials. The ``endpoint`` is either ``server`` 4910 or ``client`` depending on whether the QEMU network backend that 4911 uses the credentials will be acting as a client or as a server. 4912 For clients only, ``username`` is the username which will be 4913 sent to the server. If omitted it defaults to "qemu". 4914 4915 The dir parameter tells QEMU where to find the keys file. It is 4916 called "dir/keys.psk" and contains "username:key" pairs. This 4917 file can most easily be created using the GnuTLS ``psktool`` 4918 program. 4919 4920 For server endpoints, dir may also contain a file dh-params.pem 4921 providing diffie-hellman parameters to use for the TLS server. 4922 If the file is missing, QEMU will generate a set of DH 4923 parameters at startup. This is a computationally expensive 4924 operation that consumes random pool entropy, so it is 4925 recommended that a persistent set of parameters be generated up 4926 front and saved. 4927 4928 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id`` 4929 Creates a TLS anonymous credentials object, which can be used to 4930 provide TLS support on network backends. The ``id`` parameter is 4931 a unique ID which network backends will use to access the 4932 credentials. The ``endpoint`` is either ``server`` or ``client`` 4933 depending on whether the QEMU network backend that uses the 4934 credentials will be acting as a client or as a server. If 4935 ``verify-peer`` is enabled (the default) then once the handshake 4936 is completed, the peer credentials will be verified. With x509 4937 certificates, this implies that the clients must be provided 4938 with valid client certificates too. 4939 4940 The dir parameter tells QEMU where to find the credential files. 4941 For server endpoints, this directory may contain a file 4942 dh-params.pem providing diffie-hellman parameters to use for the 4943 TLS server. If the file is missing, QEMU will generate a set of 4944 DH parameters at startup. This is a computationally expensive 4945 operation that consumes random pool entropy, so it is 4946 recommended that a persistent set of parameters be generated 4947 upfront and saved. 4948 4949 For x509 certificate credentials the directory will contain 4950 further files providing the x509 certificates. The certificates 4951 must be stored in PEM format, in filenames ca-cert.pem, 4952 ca-crl.pem (optional), server-cert.pem (only servers), 4953 server-key.pem (only servers), client-cert.pem (only clients), 4954 and client-key.pem (only clients). 4955 4956 For the server-key.pem and client-key.pem files which contain 4957 sensitive private keys, it is possible to use an encrypted 4958 version by providing the passwordid parameter. This provides the 4959 ID of a previously created ``secret`` object containing the 4960 password for decryption. 4961 4962 The priority parameter allows to override the global default 4963 priority used by gnutls. This can be useful if the system 4964 administrator needs to use a weaker set of crypto priorities for 4965 QEMU without potentially forcing the weakness onto all 4966 applications. Or conversely if one wants wants a stronger 4967 default for QEMU than for all other applications, they can do 4968 this through this parameter. Its format is a gnutls priority 4969 string as described at 4970 https://gnutls.org/manual/html_node/Priority-Strings.html. 4971 4972 ``-object tls-cipher-suites,id=id,priority=priority`` 4973 Creates a TLS cipher suites object, which can be used to control 4974 the TLS cipher/protocol algorithms that applications are permitted 4975 to use. 4976 4977 The ``id`` parameter is a unique ID which frontends will use to 4978 access the ordered list of permitted TLS cipher suites from the 4979 host. 4980 4981 The ``priority`` parameter allows to override the global default 4982 priority used by gnutls. This can be useful if the system 4983 administrator needs to use a weaker set of crypto priorities for 4984 QEMU without potentially forcing the weakness onto all 4985 applications. Or conversely if one wants wants a stronger 4986 default for QEMU than for all other applications, they can do 4987 this through this parameter. Its format is a gnutls priority 4988 string as described at 4989 https://gnutls.org/manual/html_node/Priority-Strings.html. 4990 4991 An example of use of this object is to control UEFI HTTPS Boot. 4992 The tls-cipher-suites object exposes the ordered list of permitted 4993 TLS cipher suites from the host side to the guest firmware, via 4994 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER 4995 objects. The firmware uses the IANA_TLS_CIPHER array for configuring 4996 guest-side TLS. 4997 4998 In the following example, the priority at which the host-side policy 4999 is retrieved is given by the ``priority`` property. 5000 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to 5001 refer to /etc/crypto-policies/back-ends/gnutls.config. 5002 5003 .. parsed-literal:: 5004 5005 # |qemu_system| \\ 5006 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\ 5007 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0 5008 5009 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]`` 5010 Interval t can't be 0, this filter batches the packet delivery: 5011 all packets arriving in a given interval on netdev netdevid are 5012 delayed until the end of the interval. Interval is in 5013 microseconds. ``status`` is optional that indicate whether the 5014 netfilter is on (enabled) or off (disabled), the default status 5015 for netfilter will be 'on'. 5016 5017 queue all\|rx\|tx is an option that can be applied to any 5018 netfilter. 5019 5020 ``all``: the filter is attached both to the receive and the 5021 transmit queue of the netdev (default). 5022 5023 ``rx``: the filter is attached to the receive queue of the 5024 netdev, where it will receive packets sent to the netdev. 5025 5026 ``tx``: the filter is attached to the transmit queue of the 5027 netdev, where it will receive packets sent by the netdev. 5028 5029 position head\|tail\|id=<id> is an option to specify where the 5030 filter should be inserted in the filter list. It can be applied 5031 to any netfilter. 5032 5033 ``head``: the filter is inserted at the head of the filter list, 5034 before any existing filters. 5035 5036 ``tail``: the filter is inserted at the tail of the filter list, 5037 behind any existing filters (default). 5038 5039 ``id=<id>``: the filter is inserted before or behind the filter 5040 specified by <id>, see the insert option below. 5041 5042 insert behind\|before is an option to specify where to insert 5043 the new filter relative to the one specified with 5044 position=id=<id>. It can be applied to any netfilter. 5045 5046 ``before``: insert before the specified filter. 5047 5048 ``behind``: insert behind the specified filter (default). 5049 5050 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5051 filter-mirror on netdev netdevid,mirror net packet to 5052 chardevchardevid, if it has the vnet\_hdr\_support flag, 5053 filter-mirror will mirror packet with vnet\_hdr\_len. 5054 5055 ``-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]`` 5056 filter-redirector on netdev netdevid,redirect filter's net 5057 packet to chardev chardevid,and redirect indev's packet to 5058 filter.if it has the vnet\_hdr\_support flag, filter-redirector 5059 will redirect packet with vnet\_hdr\_len. Create a 5060 filter-redirector we need to differ outdev id from indev id, id 5061 can not be the same. we can just use indev or outdev, but at 5062 least one of indev or outdev need to be specified. 5063 5064 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5065 Filter-rewriter is a part of COLO project.It will rewrite tcp 5066 packet to secondary from primary to keep secondary tcp 5067 connection,and rewrite tcp packet to primary from secondary make 5068 tcp packet can be handled by client.if it has the 5069 vnet\_hdr\_support flag, we can parse packet with vnet header. 5070 5071 usage: colo secondary: -object 5072 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object 5073 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object 5074 filter-rewriter,id=rew0,netdev=hn0,queue=all 5075 5076 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]`` 5077 Dump the network traffic on netdev dev to the file specified by 5078 filename. At most len bytes (64k by default) per packet are 5079 stored. The file format is libpcap, so it can be analyzed with 5080 tools such as tcpdump or Wireshark. 5081 5082 ``-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}]`` 5083 Colo-compare gets packet from primary\_in chardevid and 5084 secondary\_in, then compare whether the payload of primary packet 5085 and secondary packet are the same. If same, it will output 5086 primary packet to out\_dev, else it will notify COLO-framework to do 5087 checkpoint and send primary packet to out\_dev. In order to 5088 improve efficiency, we need to put the task of comparison in 5089 another iothread. If it has the vnet\_hdr\_support flag, 5090 colo compare will send/recv packet with vnet\_hdr\_len. 5091 The compare\_timeout=@var{ms} determines the maximum time of the 5092 colo-compare hold the packet. The expired\_scan\_cycle=@var{ms} 5093 is to set the period of scanning expired primary node network packets. 5094 The max\_queue\_size=@var{size} is to set the max compare queue 5095 size depend on user environment. 5096 If user want to use Xen COLO, need to add the notify\_dev to 5097 notify Xen colo-frame to do checkpoint. 5098 5099 COLO-compare must be used with the help of filter-mirror, 5100 filter-redirector and filter-rewriter. 5101 5102 :: 5103 5104 KVM COLO 5105 5106 primary: 5107 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5108 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5109 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5110 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5111 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5112 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5113 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5114 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5115 -object iothread,id=iothread1 5116 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5117 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5118 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5119 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1 5120 5121 secondary: 5122 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5123 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5124 -chardev socket,id=red0,host=3.3.3.3,port=9003 5125 -chardev socket,id=red1,host=3.3.3.3,port=9004 5126 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5127 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5128 5129 5130 Xen COLO 5131 5132 primary: 5133 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5134 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5135 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5136 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5137 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5138 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5139 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5140 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5141 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server=on,wait=off 5142 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5143 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5144 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5145 -object iothread,id=iothread1 5146 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1 5147 5148 secondary: 5149 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5150 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5151 -chardev socket,id=red0,host=3.3.3.3,port=9003 5152 -chardev socket,id=red1,host=3.3.3.3,port=9004 5153 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5154 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5155 5156 If you want to know the detail of above command line, you can 5157 read the colo-compare git log. 5158 5159 ``-object cryptodev-backend-builtin,id=id[,queues=queues]`` 5160 Creates a cryptodev backend which executes crypto opreation from 5161 the QEMU cipher APIS. The id parameter is a unique ID that will 5162 be used to reference this cryptodev backend from the 5163 ``virtio-crypto`` device. The queues parameter is optional, 5164 which specify the queue number of cryptodev backend, the default 5165 of queues is 1. 5166 5167 .. parsed-literal:: 5168 5169 # |qemu_system| \\ 5170 [...] \\ 5171 -object cryptodev-backend-builtin,id=cryptodev0 \\ 5172 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5173 [...] 5174 5175 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]`` 5176 Creates a vhost-user cryptodev backend, backed by a chardev 5177 chardevid. The id parameter is a unique ID that will be used to 5178 reference this cryptodev backend from the ``virtio-crypto`` 5179 device. The chardev should be a unix domain socket backed one. 5180 The vhost-user uses a specifically defined protocol to pass 5181 vhost ioctl replacement messages to an application on the other 5182 end of the socket. The queues parameter is optional, which 5183 specify the queue number of cryptodev backend for multiqueue 5184 vhost-user, the default of queues is 1. 5185 5186 .. parsed-literal:: 5187 5188 # |qemu_system| \\ 5189 [...] \\ 5190 -chardev socket,id=chardev0,path=/path/to/socket \\ 5191 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\ 5192 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5193 [...] 5194 5195 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]`` 5196 \ 5197 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]`` 5198 Defines a secret to store a password, encryption key, or some 5199 other sensitive data. The sensitive data can either be passed 5200 directly via the data parameter, or indirectly via the file 5201 parameter. Using the data parameter is insecure unless the 5202 sensitive data is encrypted. 5203 5204 The sensitive data can be provided in raw format (the default), 5205 or base64. When encoded as JSON, the raw format only supports 5206 valid UTF-8 characters, so base64 is recommended for sending 5207 binary data. QEMU will convert from which ever format is 5208 provided to the format it needs internally. eg, an RBD password 5209 can be provided in raw format, even though it will be base64 5210 encoded when passed onto the RBD sever. 5211 5212 For added protection, it is possible to encrypt the data 5213 associated with a secret using the AES-256-CBC cipher. Use of 5214 encryption is indicated by providing the keyid and iv 5215 parameters. The keyid parameter provides the ID of a previously 5216 defined secret that contains the AES-256 decryption key. This 5217 key should be 32-bytes long and be base64 encoded. The iv 5218 parameter provides the random initialization vector used for 5219 encryption of this particular secret and should be a base64 5220 encrypted string of the 16-byte IV. 5221 5222 The simplest (insecure) usage is to provide the secret inline 5223 5224 .. parsed-literal:: 5225 5226 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw 5227 5228 The simplest secure usage is to provide the secret via a file 5229 5230 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object 5231 secret,id=sec0,file=mypasswd.txt,format=raw 5232 5233 For greater security, AES-256-CBC should be used. To illustrate 5234 usage, consider the openssl command line tool which can encrypt 5235 the data. Note that when encrypting, the plaintext must be 5236 padded to the cipher block size (32 bytes) using the standard 5237 PKCS#5/6 compatible padding algorithm. 5238 5239 First a master key needs to be created in base64 encoding: 5240 5241 :: 5242 5243 # openssl rand -base64 32 > key.b64 5244 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"') 5245 5246 Each secret to be encrypted needs to have a random 5247 initialization vector generated. These do not need to be kept 5248 secret 5249 5250 :: 5251 5252 # openssl rand -base64 16 > iv.b64 5253 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"') 5254 5255 The secret to be defined can now be encrypted, in this case 5256 we're telling openssl to base64 encode the result, but it could 5257 be left as raw bytes if desired. 5258 5259 :: 5260 5261 # SECRET=$(printf "letmein" | 5262 openssl enc -aes-256-cbc -a -K $KEY -iv $IV) 5263 5264 When launching QEMU, create a master secret pointing to 5265 ``key.b64`` and specify that to be used to decrypt the user 5266 password. Pass the contents of ``iv.b64`` to the second secret 5267 5268 .. parsed-literal:: 5269 5270 # |qemu_system| \\ 5271 -object secret,id=secmaster0,format=base64,file=key.b64 \\ 5272 -object secret,id=sec0,keyid=secmaster0,format=base64,\\ 5273 data=$SECRET,iv=$(<iv.b64) 5274 5275 ``-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]`` 5276 Create a Secure Encrypted Virtualization (SEV) guest object, 5277 which can be used to provide the guest memory encryption support 5278 on AMD processors. 5279 5280 When memory encryption is enabled, one of the physical address 5281 bit (aka the C-bit) is utilized to mark if a memory page is 5282 protected. The ``cbitpos`` is used to provide the C-bit 5283 position. The C-bit position is Host family dependent hence user 5284 must provide this value. On EPYC, the value should be 47. 5285 5286 When memory encryption is enabled, we loose certain bits in 5287 physical address space. The ``reduced-phys-bits`` is used to 5288 provide the number of bits we loose in physical address space. 5289 Similar to C-bit, the value is Host family dependent. On EPYC, 5290 the value should be 5. 5291 5292 The ``sev-device`` provides the device file to use for 5293 communicating with the SEV firmware running inside AMD Secure 5294 Processor. The default device is '/dev/sev'. If hardware 5295 supports memory encryption then /dev/sev devices are created by 5296 CCP driver. 5297 5298 The ``policy`` provides the guest policy to be enforced by the 5299 SEV firmware and restrict what configuration and operational 5300 commands can be performed on this guest by the hypervisor. The 5301 policy should be provided by the guest owner and is bound to the 5302 guest and cannot be changed throughout the lifetime of the 5303 guest. The default is 0. 5304 5305 If guest ``policy`` allows sharing the key with another SEV 5306 guest then ``handle`` can be use to provide handle of the guest 5307 from which to share the key. 5308 5309 The ``dh-cert-file`` and ``session-file`` provides the guest 5310 owner's Public Diffie-Hillman key defined in SEV spec. The PDH 5311 and session parameters are used for establishing a cryptographic 5312 session with the guest owner to negotiate keys used for 5313 attestation. The file must be encoded in base64. 5314 5315 The ``kernel-hashes`` adds the hashes of given kernel/initrd/ 5316 cmdline to a designated guest firmware page for measured Linux 5317 boot with -kernel. The default is off. (Since 6.2) 5318 5319 e.g to launch a SEV guest 5320 5321 .. parsed-literal:: 5322 5323 # |qemu_system_x86| \\ 5324 ...... \\ 5325 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\ 5326 -machine ...,memory-encryption=sev0 \\ 5327 ..... 5328 5329 ``-object authz-simple,id=id,identity=string`` 5330 Create an authorization object that will control access to 5331 network services. 5332 5333 The ``identity`` parameter is identifies the user and its format 5334 depends on the network service that authorization object is 5335 associated with. For authorizing based on TLS x509 certificates, 5336 the identity must be the x509 distinguished name. Note that care 5337 must be taken to escape any commas in the distinguished name. 5338 5339 An example authorization object to validate a x509 distinguished 5340 name would look like: 5341 5342 .. parsed-literal:: 5343 5344 # |qemu_system| \\ 5345 ... \\ 5346 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\ 5347 ... 5348 5349 Note the use of quotes due to the x509 distinguished name 5350 containing whitespace, and escaping of ','. 5351 5352 ``-object authz-listfile,id=id,filename=path,refresh=on|off`` 5353 Create an authorization object that will control access to 5354 network services. 5355 5356 The ``filename`` parameter is the fully qualified path to a file 5357 containing the access control list rules in JSON format. 5358 5359 An example set of rules that match against SASL usernames might 5360 look like: 5361 5362 :: 5363 5364 { 5365 "rules": [ 5366 { "match": "fred", "policy": "allow", "format": "exact" }, 5367 { "match": "bob", "policy": "allow", "format": "exact" }, 5368 { "match": "danb", "policy": "deny", "format": "glob" }, 5369 { "match": "dan*", "policy": "allow", "format": "exact" }, 5370 ], 5371 "policy": "deny" 5372 } 5373 5374 When checking access the object will iterate over all the rules 5375 and the first rule to match will have its ``policy`` value 5376 returned as the result. If no rules match, then the default 5377 ``policy`` value is returned. 5378 5379 The rules can either be an exact string match, or they can use 5380 the simple UNIX glob pattern matching to allow wildcards to be 5381 used. 5382 5383 If ``refresh`` is set to true the file will be monitored and 5384 automatically reloaded whenever its content changes. 5385 5386 As with the ``authz-simple`` object, the format of the identity 5387 strings being matched depends on the network service, but is 5388 usually a TLS x509 distinguished name, or a SASL username. 5389 5390 An example authorization object to validate a SASL username 5391 would look like: 5392 5393 .. parsed-literal:: 5394 5395 # |qemu_system| \\ 5396 ... \\ 5397 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\ 5398 ... 5399 5400 ``-object authz-pam,id=id,service=string`` 5401 Create an authorization object that will control access to 5402 network services. 5403 5404 The ``service`` parameter provides the name of a PAM service to 5405 use for authorization. It requires that a file 5406 ``/etc/pam.d/service`` exist to provide the configuration for 5407 the ``account`` subsystem. 5408 5409 An example authorization object to validate a TLS x509 5410 distinguished name would look like: 5411 5412 .. parsed-literal:: 5413 5414 # |qemu_system| \\ 5415 ... \\ 5416 -object authz-pam,id=auth0,service=qemu-vnc \\ 5417 ... 5418 5419 There would then be a corresponding config file for PAM at 5420 ``/etc/pam.d/qemu-vnc`` that contains: 5421 5422 :: 5423 5424 account requisite pam_listfile.so item=user sense=allow \ 5425 file=/etc/qemu/vnc.allow 5426 5427 Finally the ``/etc/qemu/vnc.allow`` file would contain the list 5428 of x509 distingished names that are permitted access 5429 5430 :: 5431 5432 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB 5433 5434 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch`` 5435 Creates a dedicated event loop thread that devices can be 5436 assigned to. This is known as an IOThread. By default device 5437 emulation happens in vCPU threads or the main event loop thread. 5438 This can become a scalability bottleneck. IOThreads allow device 5439 emulation and I/O to run on other host CPUs. 5440 5441 The ``id`` parameter is a unique ID that will be used to 5442 reference this IOThread from ``-device ...,iothread=id``. 5443 Multiple devices can be assigned to an IOThread. Note that not 5444 all devices support an ``iothread`` parameter. 5445 5446 The ``query-iothreads`` QMP command lists IOThreads and reports 5447 their thread IDs so that the user can configure host CPU 5448 pinning/affinity. 5449 5450 IOThreads use an adaptive polling algorithm to reduce event loop 5451 latency. Instead of entering a blocking system call to monitor 5452 file descriptors and then pay the cost of being woken up when an 5453 event occurs, the polling algorithm spins waiting for events for 5454 a short time. The algorithm's default parameters are suitable 5455 for many cases but can be adjusted based on knowledge of the 5456 workload and/or host device latency. 5457 5458 The ``poll-max-ns`` parameter is the maximum number of 5459 nanoseconds to busy wait for events. Polling can be disabled by 5460 setting this value to 0. 5461 5462 The ``poll-grow`` parameter is the multiplier used to increase 5463 the polling time when the algorithm detects it is missing events 5464 due to not polling long enough. 5465 5466 The ``poll-shrink`` parameter is the divisor used to decrease 5467 the polling time when the algorithm detects it is spending too 5468 long polling without encountering events. 5469 5470 The ``aio-max-batch`` parameter is the maximum number of requests 5471 in a batch for the AIO engine, 0 means that the engine will use 5472 its default. 5473 5474 The IOThread parameters can be modified at run-time using the 5475 ``qom-set`` command (where ``iothread1`` is the IOThread's 5476 ``id``): 5477 5478 :: 5479 5480 (qemu) qom-set /objects/iothread1 poll-max-ns 100000 5481ERST 5482 5483 5484HXCOMM This is the last statement. Insert new options before this line! 5485 5486#undef DEF 5487#undef DEFHEADING 5488#undef ARCHHEADING 5489
