1HXCOMM Use DEFHEADING() to define headings in both help text and rST. 2HXCOMM Text between SRST and ERST is copied to the rST version and 3HXCOMM discarded from C version. 4HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to 5HXCOMM construct option structures, enums and help message for specified 6HXCOMM architectures. 7HXCOMM HXCOMM can be used for comments, discarded from both rST and C. 8 9DEFHEADING(Standard options:) 10 11DEF("help", 0, QEMU_OPTION_h, 12 "-h or -help display this help and exit\n", QEMU_ARCH_ALL) 13SRST 14``-h`` 15 Display help and exit 16ERST 17 18DEF("version", 0, QEMU_OPTION_version, 19 "-version display version information and exit\n", QEMU_ARCH_ALL) 20SRST 21``-version`` 22 Display version information and exit 23ERST 24 25DEF("machine", HAS_ARG, QEMU_OPTION_machine, \ 26 "-machine [type=]name[,prop[=value][,...]]\n" 27 " selects emulated machine ('-machine help' for list)\n" 28 " property accel=accel1[:accel2[:...]] selects accelerator\n" 29 " supported accelerators are kvm, xen, hax, hvf, nvmm, whpx or tcg (default: tcg)\n" 30 " vmport=on|off|auto controls emulation of vmport (default: auto)\n" 31 " dump-guest-core=on|off include guest memory in a core dump (default=on)\n" 32 " mem-merge=on|off controls memory merge support (default: on)\n" 33 " aes-key-wrap=on|off controls support for AES key wrapping (default=on)\n" 34 " dea-key-wrap=on|off controls support for DEA key wrapping (default=on)\n" 35 " suppress-vmdesc=on|off disables self-describing migration (default=off)\n" 36 " nvdimm=on|off controls NVDIMM support (default=off)\n" 37 " memory-encryption=@var{} memory encryption object to use (default=none)\n" 38 " hmat=on|off controls ACPI HMAT support (default=off)\n" 39 " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n", 40 QEMU_ARCH_ALL) 41SRST 42``-machine [type=]name[,prop=value[,...]]`` 43 Select the emulated machine by name. Use ``-machine help`` to list 44 available machines. 45 46 For architectures which aim to support live migration compatibility 47 across releases, each release will introduce a new versioned machine 48 type. For example, the 2.8.0 release introduced machine types 49 "pc-i440fx-2.8" and "pc-q35-2.8" for the x86\_64/i686 architectures. 50 51 To allow live migration of guests from QEMU version 2.8.0, to QEMU 52 version 2.9.0, the 2.9.0 version must support the "pc-i440fx-2.8" 53 and "pc-q35-2.8" machines too. To allow users live migrating VMs to 54 skip multiple intermediate releases when upgrading, new releases of 55 QEMU will support machine types from many previous versions. 56 57 Supported machine properties are: 58 59 ``accel=accels1[:accels2[:...]]`` 60 This is used to enable an accelerator. Depending on the target 61 architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available. 62 By default, tcg is used. If there is more than one accelerator 63 specified, the next one is used if the previous one fails to 64 initialize. 65 66 ``vmport=on|off|auto`` 67 Enables emulation of VMWare IO port, for vmmouse etc. auto says 68 to select the value based on accel. For accel=xen the default is 69 off otherwise the default is on. 70 71 ``dump-guest-core=on|off`` 72 Include guest memory in a core dump. The default is on. 73 74 ``mem-merge=on|off`` 75 Enables or disables memory merge support. This feature, when 76 supported by the host, de-duplicates identical memory pages 77 among VMs instances (enabled by default). 78 79 ``aes-key-wrap=on|off`` 80 Enables or disables AES key wrapping support on s390-ccw hosts. 81 This feature controls whether AES wrapping keys will be created 82 to allow execution of AES cryptographic functions. The default 83 is on. 84 85 ``dea-key-wrap=on|off`` 86 Enables or disables DEA key wrapping support on s390-ccw hosts. 87 This feature controls whether DEA wrapping keys will be created 88 to allow execution of DEA cryptographic functions. The default 89 is on. 90 91 ``nvdimm=on|off`` 92 Enables or disables NVDIMM support. The default is off. 93 94 ``memory-encryption=`` 95 Memory encryption object to use. The default is none. 96 97 ``hmat=on|off`` 98 Enables or disables ACPI Heterogeneous Memory Attribute Table 99 (HMAT) support. The default is off. 100 101 ``memory-backend='id'`` 102 An alternative to legacy ``-mem-path`` and ``mem-prealloc`` options. 103 Allows to use a memory backend as main RAM. 104 105 For example: 106 :: 107 108 -object memory-backend-file,id=pc.ram,size=512M,mem-path=/hugetlbfs,prealloc=on,share=on 109 -machine memory-backend=pc.ram 110 -m 512M 111 112 Migration compatibility note: 113 114 * as backend id one shall use value of 'default-ram-id', advertised by 115 machine type (available via ``query-machines`` QMP command), if migration 116 to/from old QEMU (<5.0) is expected. 117 * for machine types 4.0 and older, user shall 118 use ``x-use-canonical-path-for-ramblock-id=off`` backend option 119 if migration to/from old QEMU (<5.0) is expected. 120 121 For example: 122 :: 123 124 -object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off 125 -machine memory-backend=pc.ram 126 -m 512M 127ERST 128 129DEF("M", HAS_ARG, QEMU_OPTION_M, 130 " sgx-epc.0.memdev=memid,sgx-epc.0.node=numaid\n", 131 QEMU_ARCH_ALL) 132 133SRST 134``sgx-epc.0.memdev=@var{memid},sgx-epc.0.node=@var{numaid}`` 135 Define an SGX EPC section. 136ERST 137 138DEF("cpu", HAS_ARG, QEMU_OPTION_cpu, 139 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL) 140SRST 141``-cpu model`` 142 Select CPU model (``-cpu help`` for list and additional feature 143 selection) 144ERST 145 146DEF("accel", HAS_ARG, QEMU_OPTION_accel, 147 "-accel [accel=]accelerator[,prop[=value][,...]]\n" 148 " select accelerator (kvm, xen, hax, hvf, nvmm, whpx or tcg; use 'help' for a list)\n" 149 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n" 150 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n" 151 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n" 152 " split-wx=on|off (enable TCG split w^x mapping)\n" 153 " tb-size=n (TCG translation block cache size)\n" 154 " dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n" 155 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL) 156SRST 157``-accel name[,prop=value[,...]]`` 158 This is used to enable an accelerator. Depending on the target 159 architecture, kvm, xen, hax, hvf, nvmm, whpx or tcg can be available. By 160 default, tcg is used. If there is more than one accelerator 161 specified, the next one is used if the previous one fails to 162 initialize. 163 164 ``igd-passthru=on|off`` 165 When Xen is in use, this option controls whether Intel 166 integrated graphics devices can be passed through to the guest 167 (default=off) 168 169 ``kernel-irqchip=on|off|split`` 170 Controls KVM in-kernel irqchip support. The default is full 171 acceleration of the interrupt controllers. On x86, split irqchip 172 reduces the kernel attack surface, at a performance cost for 173 non-MSI interrupts. Disabling the in-kernel irqchip completely 174 is not recommended except for debugging purposes. 175 176 ``kvm-shadow-mem=size`` 177 Defines the size of the KVM shadow MMU. 178 179 ``split-wx=on|off`` 180 Controls the use of split w^x mapping for the TCG code generation 181 buffer. Some operating systems require this to be enabled, and in 182 such a case this will default on. On other operating systems, this 183 will default off, but one may enable this for testing or debugging. 184 185 ``tb-size=n`` 186 Controls the size (in MiB) of the TCG translation block cache. 187 188 ``thread=single|multi`` 189 Controls number of TCG threads. When the TCG is multi-threaded 190 there will be one thread per vCPU therefore taking advantage of 191 additional host cores. The default is to enable multi-threading 192 where both the back-end and front-ends support it and no 193 incompatible TCG features have been enabled (e.g. 194 icount/replay). 195 196 ``dirty-ring-size=n`` 197 When the KVM accelerator is used, it controls the size of the per-vCPU 198 dirty page ring buffer (number of entries for each vCPU). It should 199 be a value that is power of two, and it should be 1024 or bigger (but 200 still less than the maximum value that the kernel supports). 4096 201 could be a good initial value if you have no idea which is the best. 202 Set this value to 0 to disable the feature. By default, this feature 203 is disabled (dirty-ring-size=0). When enabled, KVM will instead 204 record dirty pages in a bitmap. 205 206ERST 207 208DEF("smp", HAS_ARG, QEMU_OPTION_smp, 209 "-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]\n" 210 " set the number of initial CPUs to 'n' [default=1]\n" 211 " maxcpus= maximum number of total CPUs, including\n" 212 " offline CPUs for hotplug, etc\n" 213 " sockets= number of sockets on the machine board\n" 214 " dies= number of dies in one socket\n" 215 " clusters= number of clusters in one die\n" 216 " cores= number of cores in one cluster\n" 217 " threads= number of threads in one core\n" 218 "Note: Different machines may have different subsets of the CPU topology\n" 219 " parameters supported, so the actual meaning of the supported parameters\n" 220 " will vary accordingly. For example, for a machine type that supports a\n" 221 " three-level CPU hierarchy of sockets/cores/threads, the parameters will\n" 222 " sequentially mean as below:\n" 223 " sockets means the number of sockets on the machine board\n" 224 " cores means the number of cores in one socket\n" 225 " threads means the number of threads in one core\n" 226 " For a particular machine type board, an expected CPU topology hierarchy\n" 227 " can be defined through the supported sub-option. Unsupported parameters\n" 228 " can also be provided in addition to the sub-option, but their values\n" 229 " must be set as 1 in the purpose of correct parsing.\n", 230 QEMU_ARCH_ALL) 231SRST 232``-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]`` 233 Simulate a SMP system with '\ ``n``\ ' CPUs initially present on 234 the machine type board. On boards supporting CPU hotplug, the optional 235 '\ ``maxcpus``\ ' parameter can be set to enable further CPUs to be 236 added at runtime. When both parameters are omitted, the maximum number 237 of CPUs will be calculated from the provided topology members and the 238 initial CPU count will match the maximum number. When only one of them 239 is given then the omitted one will be set to its counterpart's value. 240 Both parameters may be specified, but the maximum number of CPUs must 241 be equal to or greater than the initial CPU count. Product of the 242 CPU topology hierarchy must be equal to the maximum number of CPUs. 243 Both parameters are subject to an upper limit that is determined by 244 the specific machine type chosen. 245 246 To control reporting of CPU topology information, values of the topology 247 parameters can be specified. Machines may only support a subset of the 248 parameters and different machines may have different subsets supported 249 which vary depending on capacity of the corresponding CPU targets. So 250 for a particular machine type board, an expected topology hierarchy can 251 be defined through the supported sub-option. Unsupported parameters can 252 also be provided in addition to the sub-option, but their values must be 253 set as 1 in the purpose of correct parsing. 254 255 Either the initial CPU count, or at least one of the topology parameters 256 must be specified. The specified parameters must be greater than zero, 257 explicit configuration like "cpus=0" is not allowed. Values for any 258 omitted parameters will be computed from those which are given. 259 260 For example, the following sub-option defines a CPU topology hierarchy 261 (2 sockets totally on the machine, 2 cores per socket, 2 threads per 262 core) for a machine that only supports sockets/cores/threads. 263 Some members of the option can be omitted but their values will be 264 automatically computed: 265 266 :: 267 268 -smp 8,sockets=2,cores=2,threads=2,maxcpus=8 269 270 The following sub-option defines a CPU topology hierarchy (2 sockets 271 totally on the machine, 2 dies per socket, 2 cores per die, 2 threads 272 per core) for PC machines which support sockets/dies/cores/threads. 273 Some members of the option can be omitted but their values will be 274 automatically computed: 275 276 :: 277 278 -smp 16,sockets=2,dies=2,cores=2,threads=2,maxcpus=16 279 280 The following sub-option defines a CPU topology hierarchy (2 sockets 281 totally on the machine, 2 clusters per socket, 2 cores per cluster, 282 2 threads per core) for ARM virt machines which support sockets/clusters 283 /cores/threads. Some members of the option can be omitted but their values 284 will be automatically computed: 285 286 :: 287 288 -smp 16,sockets=2,clusters=2,cores=2,threads=2,maxcpus=16 289 290 Historically preference was given to the coarsest topology parameters 291 when computing missing values (ie sockets preferred over cores, which 292 were preferred over threads), however, this behaviour is considered 293 liable to change. Prior to 6.2 the preference was sockets over cores 294 over threads. Since 6.2 the preference is cores over sockets over threads. 295 296 For example, the following option defines a machine board with 2 sockets 297 of 1 core before 6.2 and 1 socket of 2 cores after 6.2: 298 299 :: 300 301 -smp 2 302ERST 303 304DEF("numa", HAS_ARG, QEMU_OPTION_numa, 305 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 306 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n" 307 "-numa dist,src=source,dst=destination,val=distance\n" 308 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n" 309 "-numa hmat-lb,initiator=node,target=node,hierarchy=memory|first-level|second-level|third-level,data-type=access-latency|read-latency|write-latency[,latency=lat][,bandwidth=bw]\n" 310 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n", 311 QEMU_ARCH_ALL) 312SRST 313``-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 314 \ 315``-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=initiator]`` 316 \ 317``-numa dist,src=source,dst=destination,val=distance`` 318 \ 319``-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]`` 320 \ 321``-numa hmat-lb,initiator=node,target=node,hierarchy=hierarchy,data-type=tpye[,latency=lat][,bandwidth=bw]`` 322 \ 323``-numa hmat-cache,node-id=node,size=size,level=level[,associativity=str][,policy=str][,line=size]`` 324 Define a NUMA node and assign RAM and VCPUs to it. Set the NUMA 325 distance from a source node to a destination node. Set the ACPI 326 Heterogeneous Memory Attributes for the given nodes. 327 328 Legacy VCPU assignment uses '\ ``cpus``\ ' option where firstcpu and 329 lastcpu are CPU indexes. Each '\ ``cpus``\ ' option represent a 330 contiguous range of CPU indexes (or a single VCPU if lastcpu is 331 omitted). A non-contiguous set of VCPUs can be represented by 332 providing multiple '\ ``cpus``\ ' options. If '\ ``cpus``\ ' is 333 omitted on all nodes, VCPUs are automatically split between them. 334 335 For example, the following option assigns VCPUs 0, 1, 2 and 5 to a 336 NUMA node: 337 338 :: 339 340 -numa node,cpus=0-2,cpus=5 341 342 '\ ``cpu``\ ' option is a new alternative to '\ ``cpus``\ ' option 343 which uses '\ ``socket-id|core-id|thread-id``\ ' properties to 344 assign CPU objects to a node using topology layout properties of 345 CPU. The set of properties is machine specific, and depends on used 346 machine type/'\ ``smp``\ ' options. It could be queried with 347 '\ ``hotpluggable-cpus``\ ' monitor command. '\ ``node-id``\ ' 348 property specifies node to which CPU object will be assigned, it's 349 required for node to be declared with '\ ``node``\ ' option before 350 it's used with '\ ``cpu``\ ' option. 351 352 For example: 353 354 :: 355 356 -M pc \ 357 -smp 1,sockets=2,maxcpus=2 \ 358 -numa node,nodeid=0 -numa node,nodeid=1 \ 359 -numa cpu,node-id=0,socket-id=0 -numa cpu,node-id=1,socket-id=1 360 361 Legacy '\ ``mem``\ ' assigns a given RAM amount to a node (not supported 362 for 5.1 and newer machine types). '\ ``memdev``\ ' assigns RAM from 363 a given memory backend device to a node. If '\ ``mem``\ ' and 364 '\ ``memdev``\ ' are omitted in all nodes, RAM is split equally between them. 365 366 367 '\ ``mem``\ ' and '\ ``memdev``\ ' are mutually exclusive. 368 Furthermore, if one node uses '\ ``memdev``\ ', all of them have to 369 use it. 370 371 '\ ``initiator``\ ' is an additional option that points to an 372 initiator NUMA node that has best performance (the lowest latency or 373 largest bandwidth) to this NUMA node. Note that this option can be 374 set only when the machine property 'hmat' is set to 'on'. 375 376 Following example creates a machine with 2 NUMA nodes, node 0 has 377 CPU. node 1 has only memory, and its initiator is node 0. Note that 378 because node 0 has CPU, by default the initiator of node 0 is itself 379 and must be itself. 380 381 :: 382 383 -machine hmat=on \ 384 -m 2G,slots=2,maxmem=4G \ 385 -object memory-backend-ram,size=1G,id=m0 \ 386 -object memory-backend-ram,size=1G,id=m1 \ 387 -numa node,nodeid=0,memdev=m0 \ 388 -numa node,nodeid=1,memdev=m1,initiator=0 \ 389 -smp 2,sockets=2,maxcpus=2 \ 390 -numa cpu,node-id=0,socket-id=0 \ 391 -numa cpu,node-id=0,socket-id=1 392 393 source and destination are NUMA node IDs. distance is the NUMA 394 distance from source to destination. The distance from a node to 395 itself is always 10. If any pair of nodes is given a distance, then 396 all pairs must be given distances. Although, when distances are only 397 given in one direction for each pair of nodes, then the distances in 398 the opposite directions are assumed to be the same. If, however, an 399 asymmetrical pair of distances is given for even one node pair, then 400 all node pairs must be provided distance values for both directions, 401 even when they are symmetrical. When a node is unreachable from 402 another node, set the pair's distance to 255. 403 404 Note that the -``numa`` option doesn't allocate any of the specified 405 resources, it just assigns existing resources to NUMA nodes. This 406 means that one still has to use the ``-m``, ``-smp`` options to 407 allocate RAM and VCPUs respectively. 408 409 Use '\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth 410 Information between initiator and target NUMA nodes in ACPI 411 Heterogeneous Attribute Memory Table (HMAT). Initiator NUMA node can 412 create memory requests, usually it has one or more processors. 413 Target NUMA node contains addressable memory. 414 415 In '\ ``hmat-lb``\ ' option, node are NUMA node IDs. hierarchy is 416 the memory hierarchy of the target NUMA node: if hierarchy is 417 'memory', the structure represents the memory performance; if 418 hierarchy is 'first-level\|second-level\|third-level', this 419 structure represents aggregated performance of memory side caches 420 for each domain. type of 'data-type' is type of data represented by 421 this structure instance: if 'hierarchy' is 'memory', 'data-type' is 422 'access\|read\|write' latency or 'access\|read\|write' bandwidth of 423 the target memory; if 'hierarchy' is 424 'first-level\|second-level\|third-level', 'data-type' is 425 'access\|read\|write' hit latency or 'access\|read\|write' hit 426 bandwidth of the target memory side cache. 427 428 lat is latency value in nanoseconds. bw is bandwidth value, the 429 possible value and units are NUM[M\|G\|T], mean that the bandwidth 430 value are NUM byte per second (or MB/s, GB/s or TB/s depending on 431 used suffix). Note that if latency or bandwidth value is 0, means 432 the corresponding latency or bandwidth information is not provided. 433 434 In '\ ``hmat-cache``\ ' option, node-id is the NUMA-id of the memory 435 belongs. size is the size of memory side cache in bytes. level is 436 the cache level described in this structure, note that the cache 437 level 0 should not be used with '\ ``hmat-cache``\ ' option. 438 associativity is the cache associativity, the possible value is 439 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy 440 is the write policy. line is the cache Line size in bytes. 441 442 For example, the following options describe 2 NUMA nodes. Node 0 has 443 2 cpus and a ram, node 1 has only a ram. The processors in node 0 444 access memory in node 0 with access-latency 5 nanoseconds, 445 access-bandwidth is 200 MB/s; The processors in NUMA node 0 access 446 memory in NUMA node 1 with access-latency 10 nanoseconds, 447 access-bandwidth is 100 MB/s. And for memory side cache information, 448 NUMA node 0 and 1 both have 1 level memory cache, size is 10KB, 449 policy is write-back, the cache Line size is 8 bytes: 450 451 :: 452 453 -machine hmat=on \ 454 -m 2G \ 455 -object memory-backend-ram,size=1G,id=m0 \ 456 -object memory-backend-ram,size=1G,id=m1 \ 457 -smp 2,sockets=2,maxcpus=2 \ 458 -numa node,nodeid=0,memdev=m0 \ 459 -numa node,nodeid=1,memdev=m1,initiator=0 \ 460 -numa cpu,node-id=0,socket-id=0 \ 461 -numa cpu,node-id=0,socket-id=1 \ 462 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=5 \ 463 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=200M \ 464 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=10 \ 465 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=100M \ 466 -numa hmat-cache,node-id=0,size=10K,level=1,associativity=direct,policy=write-back,line=8 \ 467 -numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8 468ERST 469 470DEF("cxl-fixed-memory-window", HAS_ARG, QEMU_OPTION_cxl_fixed_memory_window, 471 "-cxl-fixed-memory-window targets.0=firsttarget,targets.1=secondtarget,size=size[,interleave-granularity=granularity]\n", 472 QEMU_ARCH_ALL) 473SRST 474``-cxl-fixed-memory-window targets.0=firsttarget,targets.1=secondtarget,size=size[,interleave-granularity=granularity]`` 475 Define a CXL Fixed Memory Window (CFMW). 476 477 Described in the CXL 2.0 ECN: CEDT CFMWS & QTG _DSM. 478 479 They are regions of Host Physical Addresses (HPA) on a system which 480 may be interleaved across one or more CXL host bridges. The system 481 software will assign particular devices into these windows and 482 configure the downstream Host-managed Device Memory (HDM) decoders 483 in root ports, switch ports and devices appropriately to meet the 484 interleave requirements before enabling the memory devices. 485 486 ``targets.X=firsttarget`` provides the mapping to CXL host bridges 487 which may be identified by the id provied in the -device entry. 488 Multiple entries are needed to specify all the targets when 489 the fixed memory window represents interleaved memory. X is the 490 target index from 0. 491 492 ``size=size`` sets the size of the CFMW. This must be a multiple of 493 256MiB. The region will be aligned to 256MiB but the location is 494 platform and configuration dependent. 495 496 ``interleave-granularity=granularity`` sets the granularity of 497 interleave. Default 256KiB. Only 256KiB, 512KiB, 1024KiB, 2048KiB 498 4096KiB, 8192KiB and 16384KiB granularities supported. 499 500 Example: 501 502 :: 503 504 -cxl-fixed-memory-window targets.0=cxl.0,targets.1=cxl.1,size=128G,interleave-granularity=512k 505 506ERST 507 508DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd, 509 "-add-fd fd=fd,set=set[,opaque=opaque]\n" 510 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL) 511SRST 512``-add-fd fd=fd,set=set[,opaque=opaque]`` 513 Add a file descriptor to an fd set. Valid options are: 514 515 ``fd=fd`` 516 This option defines the file descriptor of which a duplicate is 517 added to fd set. The file descriptor cannot be stdin, stdout, or 518 stderr. 519 520 ``set=set`` 521 This option defines the ID of the fd set to add the file 522 descriptor to. 523 524 ``opaque=opaque`` 525 This option defines a free-form string that can be used to 526 describe fd. 527 528 You can open an image using pre-opened file descriptors from an fd 529 set: 530 531 .. parsed-literal:: 532 533 |qemu_system| \\ 534 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 535 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 536 -drive file=/dev/fdset/2,index=0,media=disk 537ERST 538 539DEF("set", HAS_ARG, QEMU_OPTION_set, 540 "-set group.id.arg=value\n" 541 " set <arg> parameter for item <id> of type <group>\n" 542 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL) 543SRST 544``-set group.id.arg=value`` 545 Set parameter arg for item id of type group 546ERST 547 548DEF("global", HAS_ARG, QEMU_OPTION_global, 549 "-global driver.property=value\n" 550 "-global driver=driver,property=property,value=value\n" 551 " set a global default for a driver property\n", 552 QEMU_ARCH_ALL) 553SRST 554``-global driver.prop=value`` 555 \ 556``-global driver=driver,property=property,value=value`` 557 Set default value of driver's property prop to value, e.g.: 558 559 .. parsed-literal:: 560 561 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img 562 563 In particular, you can use this to set driver properties for devices 564 which are created automatically by the machine model. To create a 565 device which is not created automatically and set properties on it, 566 use -``device``. 567 568 -global driver.prop=value is shorthand for -global 569 driver=driver,property=prop,value=value. The longhand syntax works 570 even when driver contains a dot. 571ERST 572 573DEF("boot", HAS_ARG, QEMU_OPTION_boot, 574 "-boot [order=drives][,once=drives][,menu=on|off]\n" 575 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n" 576 " 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n" 577 " 'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n" 578 " 'sp_time': the period that splash picture last if menu=on, unit is ms\n" 579 " 'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n", 580 QEMU_ARCH_ALL) 581SRST 582``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]`` 583 Specify boot order drives as a string of drive letters. Valid drive 584 letters depend on the target architecture. The x86 PC uses: a, b 585 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p 586 (Etherboot from network adapter 1-4), hard disk boot is the default. 587 To apply a particular boot order only on the first startup, specify 588 it via ``once``. Note that the ``order`` or ``once`` parameter 589 should not be used together with the ``bootindex`` property of 590 devices, since the firmware implementations normally do not support 591 both at the same time. 592 593 Interactive boot menus/prompts can be enabled via ``menu=on`` as far 594 as firmware/BIOS supports them. The default is non-interactive boot. 595 596 A splash picture could be passed to bios, enabling user to show it 597 as logo, when option splash=sp\_name is given and menu=on, If 598 firmware/BIOS supports them. Currently Seabios for X86 system 599 support it. limitation: The splash file could be a jpeg file or a 600 BMP file in 24 BPP format(true color). The resolution should be 601 supported by the SVGA mode, so the recommended is 320x240, 640x480, 602 800x640. 603 604 A timeout could be passed to bios, guest will pause for rb\_timeout 605 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will 606 not reboot, qemu passes '-1' to bios by default. Currently Seabios 607 for X86 system support it. 608 609 Do strict boot via ``strict=on`` as far as firmware/BIOS supports 610 it. This only effects when boot priority is changed by bootindex 611 options. The default is non-strict boot. 612 613 .. parsed-literal:: 614 615 # try to boot from network first, then from hard disk 616 |qemu_system_x86| -boot order=nc 617 # boot from CD-ROM first, switch back to default order after reboot 618 |qemu_system_x86| -boot once=d 619 # boot with a splash picture for 5 seconds. 620 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000 621 622 Note: The legacy format '-boot drives' is still supported but its 623 use is discouraged as it may be removed from future versions. 624ERST 625 626DEF("m", HAS_ARG, QEMU_OPTION_m, 627 "-m [size=]megs[,slots=n,maxmem=size]\n" 628 " configure guest RAM\n" 629 " size: initial amount of guest memory\n" 630 " slots: number of hotplug slots (default: none)\n" 631 " maxmem: maximum amount of guest memory (default: none)\n" 632 "NOTE: Some architectures might enforce a specific granularity\n", 633 QEMU_ARCH_ALL) 634SRST 635``-m [size=]megs[,slots=n,maxmem=size]`` 636 Sets guest startup RAM size to megs megabytes. Default is 128 MiB. 637 Optionally, a suffix of "M" or "G" can be used to signify a value in 638 megabytes or gigabytes respectively. Optional pair slots, maxmem 639 could be used to set amount of hotpluggable memory slots and maximum 640 amount of memory. Note that maxmem must be aligned to the page size. 641 642 For example, the following command-line sets the guest startup RAM 643 size to 1GB, creates 3 slots to hotplug additional memory and sets 644 the maximum memory the guest can reach to 4GB: 645 646 .. parsed-literal:: 647 648 |qemu_system| -m 1G,slots=3,maxmem=4G 649 650 If slots and maxmem are not specified, memory hotplug won't be 651 enabled and the guest startup RAM will never increase. 652ERST 653 654DEF("mem-path", HAS_ARG, QEMU_OPTION_mempath, 655 "-mem-path FILE provide backing storage for guest RAM\n", QEMU_ARCH_ALL) 656SRST 657``-mem-path path`` 658 Allocate guest RAM from a temporarily created file in path. 659ERST 660 661DEF("mem-prealloc", 0, QEMU_OPTION_mem_prealloc, 662 "-mem-prealloc preallocate guest memory (use with -mem-path)\n", 663 QEMU_ARCH_ALL) 664SRST 665``-mem-prealloc`` 666 Preallocate memory when using -mem-path. 667ERST 668 669DEF("k", HAS_ARG, QEMU_OPTION_k, 670 "-k language use keyboard layout (for example 'fr' for French)\n", 671 QEMU_ARCH_ALL) 672SRST 673``-k language`` 674 Use keyboard layout language (for example ``fr`` for French). This 675 option is only needed where it is not easy to get raw PC keycodes 676 (e.g. on Macs, with some X11 servers or with a VNC or curses 677 display). You don't normally need to use it on PC/Linux or 678 PC/Windows hosts. 679 680 The available layouts are: 681 682 :: 683 684 ar de-ch es fo fr-ca hu ja mk no pt-br sv 685 da en-gb et fr fr-ch is lt nl pl ru th 686 de en-us fi fr-be hr it lv nl-be pt sl tr 687 688 The default is ``en-us``. 689ERST 690 691 692HXCOMM Deprecated by -audiodev 693DEF("audio-help", 0, QEMU_OPTION_audio_help, 694 "-audio-help show -audiodev equivalent of the currently specified audio settings\n", 695 QEMU_ARCH_ALL) 696SRST 697``-audio-help`` 698 Will show the -audiodev equivalent of the currently specified 699 (deprecated) environment variables. 700ERST 701 702DEF("audio", HAS_ARG, QEMU_OPTION_audio, 703 "-audio [driver=]driver,model=value[,prop[=value][,...]]\n" 704 " specifies the audio backend and device to use;\n" 705 " apart from 'model', options are the same as for -audiodev.\n" 706 " use '-audio model=help' to show possible devices.\n", 707 QEMU_ARCH_ALL) 708SRST 709``-audio [driver=]driver,model=value[,prop[=value][,...]]`` 710 This option is a shortcut for configuring both the guest audio 711 hardware and the host audio backend in one go. 712 The host backend options are the same as with the corresponding 713 ``-audiodev`` options below. The guest hardware model can be set with 714 ``model=modelname``. Use ``model=help`` to list the available device 715 types. 716 717 The following two example do exactly the same, to show how ``-audio`` 718 can be used to shorten the command line length: 719 720 .. parsed-literal:: 721 722 |qemu_system| -audiodev pa,id=pa -device sb16,audiodev=pa 723 |qemu_system| -audio pa,model=sb16 724ERST 725 726DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev, 727 "-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n" 728 " specifies the audio backend to use\n" 729 " id= identifier of the backend\n" 730 " timer-period= timer period in microseconds\n" 731 " in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n" 732 " in|out.fixed-settings= use fixed settings for host audio\n" 733 " in|out.frequency= frequency to use with fixed settings\n" 734 " in|out.channels= number of channels to use with fixed settings\n" 735 " in|out.format= sample format to use with fixed settings\n" 736 " valid values: s8, s16, s32, u8, u16, u32, f32\n" 737 " in|out.voices= number of voices to use\n" 738 " in|out.buffer-length= length of buffer in microseconds\n" 739 "-audiodev none,id=id,[,prop[=value][,...]]\n" 740 " dummy driver that discards all output\n" 741#ifdef CONFIG_AUDIO_ALSA 742 "-audiodev alsa,id=id[,prop[=value][,...]]\n" 743 " in|out.dev= name of the audio device to use\n" 744 " in|out.period-length= length of period in microseconds\n" 745 " in|out.try-poll= attempt to use poll mode\n" 746 " threshold= threshold (in microseconds) when playback starts\n" 747#endif 748#ifdef CONFIG_AUDIO_COREAUDIO 749 "-audiodev coreaudio,id=id[,prop[=value][,...]]\n" 750 " in|out.buffer-count= number of buffers\n" 751#endif 752#ifdef CONFIG_AUDIO_DSOUND 753 "-audiodev dsound,id=id[,prop[=value][,...]]\n" 754 " latency= add extra latency to playback in microseconds\n" 755#endif 756#ifdef CONFIG_AUDIO_OSS 757 "-audiodev oss,id=id[,prop[=value][,...]]\n" 758 " in|out.dev= path of the audio device to use\n" 759 " in|out.buffer-count= number of buffers\n" 760 " in|out.try-poll= attempt to use poll mode\n" 761 " try-mmap= try using memory mapped access\n" 762 " exclusive= open device in exclusive mode\n" 763 " dsp-policy= set timing policy (0..10), -1 to use fragment mode\n" 764#endif 765#ifdef CONFIG_AUDIO_PA 766 "-audiodev pa,id=id[,prop[=value][,...]]\n" 767 " server= PulseAudio server address\n" 768 " in|out.name= source/sink device name\n" 769 " in|out.latency= desired latency in microseconds\n" 770#endif 771#ifdef CONFIG_AUDIO_SDL 772 "-audiodev sdl,id=id[,prop[=value][,...]]\n" 773 " in|out.buffer-count= number of buffers\n" 774#endif 775#ifdef CONFIG_SPICE 776 "-audiodev spice,id=id[,prop[=value][,...]]\n" 777#endif 778#ifdef CONFIG_DBUS_DISPLAY 779 "-audiodev dbus,id=id[,prop[=value][,...]]\n" 780#endif 781 "-audiodev wav,id=id[,prop[=value][,...]]\n" 782 " path= path of wav file to record\n", 783 QEMU_ARCH_ALL) 784SRST 785``-audiodev [driver=]driver,id=id[,prop[=value][,...]]`` 786 Adds a new audio backend driver identified by id. There are global 787 and driver specific properties. Some values can be set differently 788 for input and output, they're marked with ``in|out.``. You can set 789 the input's property with ``in.prop`` and the output's property with 790 ``out.prop``. For example: 791 792 :: 793 794 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000 795 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified 796 797 NOTE: parameter validation is known to be incomplete, in many cases 798 specifying an invalid option causes QEMU to print an error message 799 and continue emulation without sound. 800 801 Valid global options are: 802 803 ``id=identifier`` 804 Identifies the audio backend. 805 806 ``timer-period=period`` 807 Sets the timer period used by the audio subsystem in 808 microseconds. Default is 10000 (10 ms). 809 810 ``in|out.mixing-engine=on|off`` 811 Use QEMU's mixing engine to mix all streams inside QEMU and 812 convert audio formats when not supported by the backend. When 813 off, fixed-settings must be off too. Note that disabling this 814 option means that the selected backend must support multiple 815 streams and the audio formats used by the virtual cards, 816 otherwise you'll get no sound. It's not recommended to disable 817 this option unless you want to use 5.1 or 7.1 audio, as mixing 818 engine only supports mono and stereo audio. Default is on. 819 820 ``in|out.fixed-settings=on|off`` 821 Use fixed settings for host audio. When off, it will change 822 based on how the guest opens the sound card. In this case you 823 must not specify frequency, channels or format. Default is on. 824 825 ``in|out.frequency=frequency`` 826 Specify the frequency to use when using fixed-settings. Default 827 is 44100Hz. 828 829 ``in|out.channels=channels`` 830 Specify the number of channels to use when using fixed-settings. 831 Default is 2 (stereo). 832 833 ``in|out.format=format`` 834 Specify the sample format to use when using fixed-settings. 835 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``, 836 ``u32``, ``f32``. Default is ``s16``. 837 838 ``in|out.voices=voices`` 839 Specify the number of voices to use. Default is 1. 840 841 ``in|out.buffer-length=usecs`` 842 Sets the size of the buffer in microseconds. 843 844``-audiodev none,id=id[,prop[=value][,...]]`` 845 Creates a dummy backend that discards all outputs. This backend has 846 no backend specific properties. 847 848``-audiodev alsa,id=id[,prop[=value][,...]]`` 849 Creates backend using the ALSA. This backend is only available on 850 Linux. 851 852 ALSA specific options are: 853 854 ``in|out.dev=device`` 855 Specify the ALSA device to use for input and/or output. Default 856 is ``default``. 857 858 ``in|out.period-length=usecs`` 859 Sets the period length in microseconds. 860 861 ``in|out.try-poll=on|off`` 862 Attempt to use poll mode with the device. Default is on. 863 864 ``threshold=threshold`` 865 Threshold (in microseconds) when playback starts. Default is 0. 866 867``-audiodev coreaudio,id=id[,prop[=value][,...]]`` 868 Creates a backend using Apple's Core Audio. This backend is only 869 available on Mac OS and only supports playback. 870 871 Core Audio specific options are: 872 873 ``in|out.buffer-count=count`` 874 Sets the count of the buffers. 875 876``-audiodev dsound,id=id[,prop[=value][,...]]`` 877 Creates a backend using Microsoft's DirectSound. This backend is 878 only available on Windows and only supports playback. 879 880 DirectSound specific options are: 881 882 ``latency=usecs`` 883 Add extra usecs microseconds latency to playback. Default is 884 10000 (10 ms). 885 886``-audiodev oss,id=id[,prop[=value][,...]]`` 887 Creates a backend using OSS. This backend is available on most 888 Unix-like systems. 889 890 OSS specific options are: 891 892 ``in|out.dev=device`` 893 Specify the file name of the OSS device to use. Default is 894 ``/dev/dsp``. 895 896 ``in|out.buffer-count=count`` 897 Sets the count of the buffers. 898 899 ``in|out.try-poll=on|of`` 900 Attempt to use poll mode with the device. Default is on. 901 902 ``try-mmap=on|off`` 903 Try using memory mapped device access. Default is off. 904 905 ``exclusive=on|off`` 906 Open the device in exclusive mode (vmix won't work in this 907 case). Default is off. 908 909 ``dsp-policy=policy`` 910 Sets the timing policy (between 0 and 10, where smaller number 911 means smaller latency but higher CPU usage). Use -1 to use 912 buffer sizes specified by ``buffer`` and ``buffer-count``. This 913 option is ignored if you do not have OSS 4. Default is 5. 914 915``-audiodev pa,id=id[,prop[=value][,...]]`` 916 Creates a backend using PulseAudio. This backend is available on 917 most systems. 918 919 PulseAudio specific options are: 920 921 ``server=server`` 922 Sets the PulseAudio server to connect to. 923 924 ``in|out.name=sink`` 925 Use the specified source/sink for recording/playback. 926 927 ``in|out.latency=usecs`` 928 Desired latency in microseconds. The PulseAudio server will try 929 to honor this value but actual latencies may be lower or higher. 930 931``-audiodev sdl,id=id[,prop[=value][,...]]`` 932 Creates a backend using SDL. This backend is available on most 933 systems, but you should use your platform's native backend if 934 possible. 935 936 SDL specific options are: 937 938 ``in|out.buffer-count=count`` 939 Sets the count of the buffers. 940 941``-audiodev spice,id=id[,prop[=value][,...]]`` 942 Creates a backend that sends audio through SPICE. This backend 943 requires ``-spice`` and automatically selected in that case, so 944 usually you can ignore this option. This backend has no backend 945 specific properties. 946 947``-audiodev wav,id=id[,prop[=value][,...]]`` 948 Creates a backend that writes audio to a WAV file. 949 950 Backend specific options are: 951 952 ``path=path`` 953 Write recorded audio into the specified file. Default is 954 ``qemu.wav``. 955ERST 956 957DEF("device", HAS_ARG, QEMU_OPTION_device, 958 "-device driver[,prop[=value][,...]]\n" 959 " add device (based on driver)\n" 960 " prop=value,... sets driver properties\n" 961 " use '-device help' to print all possible drivers\n" 962 " use '-device driver,help' to print all possible properties\n", 963 QEMU_ARCH_ALL) 964SRST 965``-device driver[,prop[=value][,...]]`` 966 Add device driver. prop=value sets driver properties. Valid 967 properties depend on the driver. To get help on possible drivers and 968 properties, use ``-device help`` and ``-device driver,help``. 969 970 Some drivers are: 971 972``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]`` 973 Add an IPMI BMC. This is a simulation of a hardware management 974 interface processor that normally sits on a system. It provides a 975 watchdog and the ability to reset and power control the system. You 976 need to connect this to an IPMI interface to make it useful 977 978 The IPMI slave address to use for the BMC. The default is 0x20. This 979 address is the BMC's address on the I2C network of management 980 controllers. If you don't know what this means, it is safe to ignore 981 it. 982 983 ``id=id`` 984 The BMC id for interfaces to use this device. 985 986 ``slave_addr=val`` 987 Define slave address to use for the BMC. The default is 0x20. 988 989 ``sdrfile=file`` 990 file containing raw Sensor Data Records (SDR) data. The default 991 is none. 992 993 ``fruareasize=val`` 994 size of a Field Replaceable Unit (FRU) area. The default is 995 1024. 996 997 ``frudatafile=file`` 998 file containing raw Field Replaceable Unit (FRU) inventory data. 999 The default is none. 1000 1001 ``guid=uuid`` 1002 value for the GUID for the BMC, in standard UUID format. If this 1003 is set, get "Get GUID" command to the BMC will return it. 1004 Otherwise "Get GUID" will return an error. 1005 1006``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]`` 1007 Add a connection to an external IPMI BMC simulator. Instead of 1008 locally emulating the BMC like the above item, instead connect to an 1009 external entity that provides the IPMI services. 1010 1011 A connection is made to an external BMC simulator. If you do this, 1012 it is strongly recommended that you use the "reconnect=" chardev 1013 option to reconnect to the simulator if the connection is lost. Note 1014 that if this is not used carefully, it can be a security issue, as 1015 the interface has the ability to send resets, NMIs, and power off 1016 the VM. It's best if QEMU makes a connection to an external 1017 simulator running on a secure port on localhost, so neither the 1018 simulator nor QEMU is exposed to any outside network. 1019 1020 See the "lanserv/README.vm" file in the OpenIPMI library for more 1021 details on the external interface. 1022 1023``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]`` 1024 Add a KCS IPMI interafce on the ISA bus. This also adds a 1025 corresponding ACPI and SMBIOS entries, if appropriate. 1026 1027 ``bmc=id`` 1028 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern 1029 above. 1030 1031 ``ioport=val`` 1032 Define the I/O address of the interface. The default is 0xca0 1033 for KCS. 1034 1035 ``irq=val`` 1036 Define the interrupt to use. The default is 5. To disable 1037 interrupts, set this to 0. 1038 1039``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]`` 1040 Like the KCS interface, but defines a BT interface. The default port 1041 is 0xe4 and the default interrupt is 5. 1042 1043``-device pci-ipmi-kcs,bmc=id`` 1044 Add a KCS IPMI interafce on the PCI bus. 1045 1046 ``bmc=id`` 1047 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above. 1048 1049``-device pci-ipmi-bt,bmc=id`` 1050 Like the KCS interface, but defines a BT interface on the PCI bus. 1051 1052``-device intel-iommu[,option=...]`` 1053 This is only supported by ``-machine q35``, which will enable Intel VT-d 1054 emulation within the guest. It supports below options: 1055 1056 ``intremap=on|off`` (default: auto) 1057 This enables interrupt remapping feature. It's required to enable 1058 complete x2apic. Currently it only supports kvm kernel-irqchip modes 1059 ``off`` or ``split``, while full kernel-irqchip is not yet supported. 1060 The default value is "auto", which will be decided by the mode of 1061 kernel-irqchip. 1062 1063 ``caching-mode=on|off`` (default: off) 1064 This enables caching mode for the VT-d emulated device. When 1065 caching-mode is enabled, each guest DMA buffer mapping will generate an 1066 IOTLB invalidation from the guest IOMMU driver to the vIOMMU device in 1067 a synchronous way. It is required for ``-device vfio-pci`` to work 1068 with the VT-d device, because host assigned devices requires to setup 1069 the DMA mapping on the host before guest DMA starts. 1070 1071 ``device-iotlb=on|off`` (default: off) 1072 This enables device-iotlb capability for the emulated VT-d device. So 1073 far virtio/vhost should be the only real user for this parameter, 1074 paired with ats=on configured for the device. 1075 1076 ``aw-bits=39|48`` (default: 39) 1077 This decides the address width of IOVA address space. The address 1078 space has 39 bits width for 3-level IOMMU page tables, and 48 bits for 1079 4-level IOMMU page tables. 1080 1081 Please also refer to the wiki page for general scenarios of VT-d 1082 emulation in QEMU: https://wiki.qemu.org/Features/VT-d. 1083 1084ERST 1085 1086DEF("name", HAS_ARG, QEMU_OPTION_name, 1087 "-name string1[,process=string2][,debug-threads=on|off]\n" 1088 " set the name of the guest\n" 1089 " string1 sets the window title and string2 the process name\n" 1090 " When debug-threads is enabled, individual threads are given a separate name\n" 1091 " NOTE: The thread names are for debugging and not a stable API.\n", 1092 QEMU_ARCH_ALL) 1093SRST 1094``-name name`` 1095 Sets the name of the guest. This name will be displayed in the SDL 1096 window caption. The name will also be used for the VNC server. Also 1097 optionally set the top visible process name in Linux. Naming of 1098 individual threads can also be enabled on Linux to aid debugging. 1099ERST 1100 1101DEF("uuid", HAS_ARG, QEMU_OPTION_uuid, 1102 "-uuid %08x-%04x-%04x-%04x-%012x\n" 1103 " specify machine UUID\n", QEMU_ARCH_ALL) 1104SRST 1105``-uuid uuid`` 1106 Set system UUID. 1107ERST 1108 1109DEFHEADING() 1110 1111DEFHEADING(Block device options:) 1112 1113DEF("fda", HAS_ARG, QEMU_OPTION_fda, 1114 "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL) 1115DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL) 1116SRST 1117``-fda file`` 1118 \ 1119``-fdb file`` 1120 Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in 1121 the System Emulation Users Guide). 1122ERST 1123 1124DEF("hda", HAS_ARG, QEMU_OPTION_hda, 1125 "-hda/-hdb file use 'file' as IDE hard disk 0/1 image\n", QEMU_ARCH_ALL) 1126DEF("hdb", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL) 1127DEF("hdc", HAS_ARG, QEMU_OPTION_hdc, 1128 "-hdc/-hdd file use 'file' as IDE hard disk 2/3 image\n", QEMU_ARCH_ALL) 1129DEF("hdd", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL) 1130SRST 1131``-hda file`` 1132 \ 1133``-hdb file`` 1134 \ 1135``-hdc file`` 1136 \ 1137``-hdd file`` 1138 Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images` 1139 chapter in the System Emulation Users Guide). 1140ERST 1141 1142DEF("cdrom", HAS_ARG, QEMU_OPTION_cdrom, 1143 "-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n", 1144 QEMU_ARCH_ALL) 1145SRST 1146``-cdrom file`` 1147 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at 1148 the same time). You can use the host CD-ROM by using ``/dev/cdrom`` 1149 as filename. 1150ERST 1151 1152DEF("blockdev", HAS_ARG, QEMU_OPTION_blockdev, 1153 "-blockdev [driver=]driver[,node-name=N][,discard=ignore|unmap]\n" 1154 " [,cache.direct=on|off][,cache.no-flush=on|off]\n" 1155 " [,read-only=on|off][,auto-read-only=on|off]\n" 1156 " [,force-share=on|off][,detect-zeroes=on|off|unmap]\n" 1157 " [,driver specific parameters...]\n" 1158 " configure a block backend\n", QEMU_ARCH_ALL) 1159SRST 1160``-blockdev option[,option[,option[,...]]]`` 1161 Define a new block driver node. Some of the options apply to all 1162 block drivers, other options are only accepted for a specific block 1163 driver. See below for a list of generic options and options for the 1164 most common block drivers. 1165 1166 Options that expect a reference to another node (e.g. ``file``) can 1167 be given in two ways. Either you specify the node name of an already 1168 existing node (file=node-name), or you define a new node inline, 1169 adding options for the referenced node after a dot 1170 (file.filename=path,file.aio=native). 1171 1172 A block driver node created with ``-blockdev`` can be used for a 1173 guest device by specifying its node name for the ``drive`` property 1174 in a ``-device`` argument that defines a block device. 1175 1176 ``Valid options for any block driver node:`` 1177 ``driver`` 1178 Specifies the block driver to use for the given node. 1179 1180 ``node-name`` 1181 This defines the name of the block driver node by which it 1182 will be referenced later. The name must be unique, i.e. it 1183 must not match the name of a different block driver node, or 1184 (if you use ``-drive`` as well) the ID of a drive. 1185 1186 If no node name is specified, it is automatically generated. 1187 The generated node name is not intended to be predictable 1188 and changes between QEMU invocations. For the top level, an 1189 explicit node name must be specified. 1190 1191 ``read-only`` 1192 Open the node read-only. Guest write attempts will fail. 1193 1194 Note that some block drivers support only read-only access, 1195 either generally or in certain configurations. In this case, 1196 the default value ``read-only=off`` does not work and the 1197 option must be specified explicitly. 1198 1199 ``auto-read-only`` 1200 If ``auto-read-only=on`` is set, QEMU may fall back to 1201 read-only usage even when ``read-only=off`` is requested, or 1202 even switch between modes as needed, e.g. depending on 1203 whether the image file is writable or whether a writing user 1204 is attached to the node. 1205 1206 ``force-share`` 1207 Override the image locking system of QEMU by forcing the 1208 node to utilize weaker shared access for permissions where 1209 it would normally request exclusive access. When there is 1210 the potential for multiple instances to have the same file 1211 open (whether this invocation of QEMU is the first or the 1212 second instance), both instances must permit shared access 1213 for the second instance to succeed at opening the file. 1214 1215 Enabling ``force-share=on`` requires ``read-only=on``. 1216 1217 ``cache.direct`` 1218 The host page cache can be avoided with ``cache.direct=on``. 1219 This will attempt to do disk IO directly to the guest's 1220 memory. QEMU may still perform an internal copy of the data. 1221 1222 ``cache.no-flush`` 1223 In case you don't care about data integrity over host 1224 failures, you can use ``cache.no-flush=on``. This option 1225 tells QEMU that it never needs to write any data to the disk 1226 but can instead keep things in cache. If anything goes 1227 wrong, like your host losing power, the disk storage getting 1228 disconnected accidentally, etc. your image will most 1229 probably be rendered unusable. 1230 1231 ``discard=discard`` 1232 discard is one of "ignore" (or "off") or "unmap" (or "on") 1233 and controls whether ``discard`` (also known as ``trim`` or 1234 ``unmap``) requests are ignored or passed to the filesystem. 1235 Some machine types may not support discard requests. 1236 1237 ``detect-zeroes=detect-zeroes`` 1238 detect-zeroes is "off", "on" or "unmap" and enables the 1239 automatic conversion of plain zero writes by the OS to 1240 driver specific optimized zero write commands. You may even 1241 choose "unmap" if discard is set to "unmap" to allow a zero 1242 write to be converted to an ``unmap`` operation. 1243 1244 ``Driver-specific options for file`` 1245 This is the protocol-level block driver for accessing regular 1246 files. 1247 1248 ``filename`` 1249 The path to the image file in the local filesystem 1250 1251 ``aio`` 1252 Specifies the AIO backend (threads/native/io_uring, 1253 default: threads) 1254 1255 ``locking`` 1256 Specifies whether the image file is protected with Linux OFD 1257 / POSIX locks. The default is to use the Linux Open File 1258 Descriptor API if available, otherwise no lock is applied. 1259 (auto/on/off, default: auto) 1260 1261 Example: 1262 1263 :: 1264 1265 -blockdev driver=file,node-name=disk,filename=disk.img 1266 1267 ``Driver-specific options for raw`` 1268 This is the image format block driver for raw images. It is 1269 usually stacked on top of a protocol level block driver such as 1270 ``file``. 1271 1272 ``file`` 1273 Reference to or definition of the data source block driver 1274 node (e.g. a ``file`` driver node) 1275 1276 Example 1: 1277 1278 :: 1279 1280 -blockdev driver=file,node-name=disk_file,filename=disk.img 1281 -blockdev driver=raw,node-name=disk,file=disk_file 1282 1283 Example 2: 1284 1285 :: 1286 1287 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img 1288 1289 ``Driver-specific options for qcow2`` 1290 This is the image format block driver for qcow2 images. It is 1291 usually stacked on top of a protocol level block driver such as 1292 ``file``. 1293 1294 ``file`` 1295 Reference to or definition of the data source block driver 1296 node (e.g. a ``file`` driver node) 1297 1298 ``backing`` 1299 Reference to or definition of the backing file block device 1300 (default is taken from the image file). It is allowed to 1301 pass ``null`` here in order to disable the default backing 1302 file. 1303 1304 ``lazy-refcounts`` 1305 Whether to enable the lazy refcounts feature (on/off; 1306 default is taken from the image file) 1307 1308 ``cache-size`` 1309 The maximum total size of the L2 table and refcount block 1310 caches in bytes (default: the sum of l2-cache-size and 1311 refcount-cache-size) 1312 1313 ``l2-cache-size`` 1314 The maximum size of the L2 table cache in bytes (default: if 1315 cache-size is not specified - 32M on Linux platforms, and 8M 1316 on non-Linux platforms; otherwise, as large as possible 1317 within the cache-size, while permitting the requested or the 1318 minimal refcount cache size) 1319 1320 ``refcount-cache-size`` 1321 The maximum size of the refcount block cache in bytes 1322 (default: 4 times the cluster size; or if cache-size is 1323 specified, the part of it which is not used for the L2 1324 cache) 1325 1326 ``cache-clean-interval`` 1327 Clean unused entries in the L2 and refcount caches. The 1328 interval is in seconds. The default value is 600 on 1329 supporting platforms, and 0 on other platforms. Setting it 1330 to 0 disables this feature. 1331 1332 ``pass-discard-request`` 1333 Whether discard requests to the qcow2 device should be 1334 forwarded to the data source (on/off; default: on if 1335 discard=unmap is specified, off otherwise) 1336 1337 ``pass-discard-snapshot`` 1338 Whether discard requests for the data source should be 1339 issued when a snapshot operation (e.g. deleting a snapshot) 1340 frees clusters in the qcow2 file (on/off; default: on) 1341 1342 ``pass-discard-other`` 1343 Whether discard requests for the data source should be 1344 issued on other occasions where a cluster gets freed 1345 (on/off; default: off) 1346 1347 ``overlap-check`` 1348 Which overlap checks to perform for writes to the image 1349 (none/constant/cached/all; default: cached). For details or 1350 finer granularity control refer to the QAPI documentation of 1351 ``blockdev-add``. 1352 1353 Example 1: 1354 1355 :: 1356 1357 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2 1358 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216 1359 1360 Example 2: 1361 1362 :: 1363 1364 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2 1365 1366 ``Driver-specific options for other drivers`` 1367 Please refer to the QAPI documentation of the ``blockdev-add`` 1368 QMP command. 1369ERST 1370 1371DEF("drive", HAS_ARG, QEMU_OPTION_drive, 1372 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" 1373 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" 1374 " [,snapshot=on|off][,rerror=ignore|stop|report]\n" 1375 " [,werror=ignore|stop|report|enospc][,id=name]\n" 1376 " [,aio=threads|native|io_uring]\n" 1377 " [,readonly=on|off][,copy-on-read=on|off]\n" 1378 " [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n" 1379 " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n" 1380 " [[,iops=i]|[[,iops_rd=r][,iops_wr=w]]]\n" 1381 " [[,bps_max=bm]|[[,bps_rd_max=rm][,bps_wr_max=wm]]]\n" 1382 " [[,iops_max=im]|[[,iops_rd_max=irm][,iops_wr_max=iwm]]]\n" 1383 " [[,iops_size=is]]\n" 1384 " [[,group=g]]\n" 1385 " use 'file' as a drive image\n", QEMU_ARCH_ALL) 1386SRST 1387``-drive option[,option[,option[,...]]]`` 1388 Define a new drive. This includes creating a block driver node (the 1389 backend) as well as a guest device, and is mostly a shortcut for 1390 defining the corresponding ``-blockdev`` and ``-device`` options. 1391 1392 ``-drive`` accepts all options that are accepted by ``-blockdev``. 1393 In addition, it knows the following options: 1394 1395 ``file=file`` 1396 This option defines which disk image (see the :ref:`disk images` 1397 chapter in the System Emulation Users Guide) to use with this drive. 1398 If the filename contains comma, you must double it (for instance, 1399 "file=my,,file" to use file "my,file"). 1400 1401 Special files such as iSCSI devices can be specified using 1402 protocol specific URLs. See the section for "Device URL Syntax" 1403 for more information. 1404 1405 ``if=interface`` 1406 This option defines on which type on interface the drive is 1407 connected. Available types are: ide, scsi, sd, mtd, floppy, 1408 pflash, virtio, none. 1409 1410 ``bus=bus,unit=unit`` 1411 These options define where is connected the drive by defining 1412 the bus number and the unit id. 1413 1414 ``index=index`` 1415 This option defines where the drive is connected by using an 1416 index in the list of available connectors of a given interface 1417 type. 1418 1419 ``media=media`` 1420 This option defines the type of the media: disk or cdrom. 1421 1422 ``snapshot=snapshot`` 1423 snapshot is "on" or "off" and controls snapshot mode for the 1424 given drive (see ``-snapshot``). 1425 1426 ``cache=cache`` 1427 cache is "none", "writeback", "unsafe", "directsync" or 1428 "writethrough" and controls how the host cache is used to access 1429 block data. This is a shortcut that sets the ``cache.direct`` 1430 and ``cache.no-flush`` options (as in ``-blockdev``), and 1431 additionally ``cache.writeback``, which provides a default for 1432 the ``write-cache`` option of block guest devices (as in 1433 ``-device``). The modes correspond to the following settings: 1434 1435 ============= =============== ============ ============== 1436 \ cache.writeback cache.direct cache.no-flush 1437 ============= =============== ============ ============== 1438 writeback on off off 1439 none on on off 1440 writethrough off off off 1441 directsync off on off 1442 unsafe on off on 1443 ============= =============== ============ ============== 1444 1445 The default mode is ``cache=writeback``. 1446 1447 ``aio=aio`` 1448 aio is "threads", "native", or "io_uring" and selects between pthread 1449 based disk I/O, native Linux AIO, or Linux io_uring API. 1450 1451 ``format=format`` 1452 Specify which disk format will be used rather than detecting the 1453 format. Can be used to specify format=raw to avoid interpreting 1454 an untrusted format header. 1455 1456 ``werror=action,rerror=action`` 1457 Specify which action to take on write and read errors. Valid 1458 actions are: "ignore" (ignore the error and try to continue), 1459 "stop" (pause QEMU), "report" (report the error to the guest), 1460 "enospc" (pause QEMU only if the host disk is full; report the 1461 error to the guest otherwise). The default setting is 1462 ``werror=enospc`` and ``rerror=report``. 1463 1464 ``copy-on-read=copy-on-read`` 1465 copy-on-read is "on" or "off" and enables whether to copy read 1466 backing file sectors into the image file. 1467 1468 ``bps=b,bps_rd=r,bps_wr=w`` 1469 Specify bandwidth throttling limits in bytes per second, either 1470 for all request types or for reads or writes only. Small values 1471 can lead to timeouts or hangs inside the guest. A safe minimum 1472 for disks is 2 MB/s. 1473 1474 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm`` 1475 Specify bursts in bytes per second, either for all request types 1476 or for reads or writes only. Bursts allow the guest I/O to spike 1477 above the limit temporarily. 1478 1479 ``iops=i,iops_rd=r,iops_wr=w`` 1480 Specify request rate limits in requests per second, either for 1481 all request types or for reads or writes only. 1482 1483 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm`` 1484 Specify bursts in requests per second, either for all request 1485 types or for reads or writes only. Bursts allow the guest I/O to 1486 spike above the limit temporarily. 1487 1488 ``iops_size=is`` 1489 Let every is bytes of a request count as a new request for iops 1490 throttling purposes. Use this option to prevent guests from 1491 circumventing iops limits by sending fewer but larger requests. 1492 1493 ``group=g`` 1494 Join a throttling quota group with given name g. All drives that 1495 are members of the same group are accounted for together. Use 1496 this option to prevent guests from circumventing throttling 1497 limits by using many small disks instead of a single larger 1498 disk. 1499 1500 By default, the ``cache.writeback=on`` mode is used. It will report 1501 data writes as completed as soon as the data is present in the host 1502 page cache. This is safe as long as your guest OS makes sure to 1503 correctly flush disk caches where needed. If your guest OS does not 1504 handle volatile disk write caches correctly and your host crashes or 1505 loses power, then the guest may experience data corruption. 1506 1507 For such guests, you should consider using ``cache.writeback=off``. 1508 This means that the host page cache will be used to read and write 1509 data, but write notification will be sent to the guest only after 1510 QEMU has made sure to flush each write to the disk. Be aware that 1511 this has a major impact on performance. 1512 1513 When using the ``-snapshot`` option, unsafe caching is always used. 1514 1515 Copy-on-read avoids accessing the same backing file sectors 1516 repeatedly and is useful when the backing file is over a slow 1517 network. By default copy-on-read is off. 1518 1519 Instead of ``-cdrom`` you can use: 1520 1521 .. parsed-literal:: 1522 1523 |qemu_system| -drive file=file,index=2,media=cdrom 1524 1525 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use: 1526 1527 .. parsed-literal:: 1528 1529 |qemu_system| -drive file=file,index=0,media=disk 1530 |qemu_system| -drive file=file,index=1,media=disk 1531 |qemu_system| -drive file=file,index=2,media=disk 1532 |qemu_system| -drive file=file,index=3,media=disk 1533 1534 You can open an image using pre-opened file descriptors from an fd 1535 set: 1536 1537 .. parsed-literal:: 1538 1539 |qemu_system| \\ 1540 -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" \\ 1541 -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" \\ 1542 -drive file=/dev/fdset/2,index=0,media=disk 1543 1544 You can connect a CDROM to the slave of ide0: 1545 1546 .. parsed-literal:: 1547 1548 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom 1549 1550 If you don't specify the "file=" argument, you define an empty 1551 drive: 1552 1553 .. parsed-literal:: 1554 1555 |qemu_system_x86| -drive if=ide,index=1,media=cdrom 1556 1557 Instead of ``-fda``, ``-fdb``, you can use: 1558 1559 .. parsed-literal:: 1560 1561 |qemu_system_x86| -drive file=file,index=0,if=floppy 1562 |qemu_system_x86| -drive file=file,index=1,if=floppy 1563 1564 By default, interface is "ide" and index is automatically 1565 incremented: 1566 1567 .. parsed-literal:: 1568 1569 |qemu_system_x86| -drive file=a -drive file=b" 1570 1571 is interpreted like: 1572 1573 .. parsed-literal:: 1574 1575 |qemu_system_x86| -hda a -hdb b 1576ERST 1577 1578DEF("mtdblock", HAS_ARG, QEMU_OPTION_mtdblock, 1579 "-mtdblock file use 'file' as on-board Flash memory image\n", 1580 QEMU_ARCH_ALL) 1581SRST 1582``-mtdblock file`` 1583 Use file as on-board Flash memory image. 1584ERST 1585 1586DEF("sd", HAS_ARG, QEMU_OPTION_sd, 1587 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL) 1588SRST 1589``-sd file`` 1590 Use file as SecureDigital card image. 1591ERST 1592 1593DEF("pflash", HAS_ARG, QEMU_OPTION_pflash, 1594 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL) 1595SRST 1596``-pflash file`` 1597 Use file as a parallel flash image. 1598ERST 1599 1600DEF("snapshot", 0, QEMU_OPTION_snapshot, 1601 "-snapshot write to temporary files instead of disk image files\n", 1602 QEMU_ARCH_ALL) 1603SRST 1604``-snapshot`` 1605 Write to temporary files instead of disk image files. In this case, 1606 the raw disk image you use is not written back. You can however 1607 force the write back by pressing C-a s (see the :ref:`disk images` 1608 chapter in the System Emulation Users Guide). 1609ERST 1610 1611DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev, 1612 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1613 " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n" 1614 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n" 1615 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n" 1616 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n" 1617 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n" 1618 " [[,throttling.iops-size=is]]\n" 1619 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n" 1620 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n" 1621 "-fsdev synth,id=id\n", 1622 QEMU_ARCH_ALL) 1623 1624SRST 1625``-fsdev local,id=id,path=path,security_model=security_model [,writeout=writeout][,readonly=on][,fmode=fmode][,dmode=dmode] [,throttling.option=value[,throttling.option=value[,...]]]`` 1626 \ 1627``-fsdev proxy,id=id,socket=socket[,writeout=writeout][,readonly=on]`` 1628 \ 1629``-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=writeout][,readonly=on]`` 1630 \ 1631``-fsdev synth,id=id[,readonly=on]`` 1632 Define a new file system device. Valid options are: 1633 1634 ``local`` 1635 Accesses to the filesystem are done by QEMU. 1636 1637 ``proxy`` 1638 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1639 1640 ``synth`` 1641 Synthetic filesystem, only used by QTests. 1642 1643 ``id=id`` 1644 Specifies identifier for this device. 1645 1646 ``path=path`` 1647 Specifies the export path for the file system device. Files 1648 under this path will be available to the 9p client on the guest. 1649 1650 ``security_model=security_model`` 1651 Specifies the security model to be used for this export path. 1652 Supported security models are "passthrough", "mapped-xattr", 1653 "mapped-file" and "none". In "passthrough" security model, files 1654 are stored using the same credentials as they are created on the 1655 guest. This requires QEMU to run as root. In "mapped-xattr" 1656 security model, some of the file attributes like uid, gid, mode 1657 bits and link target are stored as file attributes. For 1658 "mapped-file" these attributes are stored in the hidden 1659 .virtfs\_metadata directory. Directories exported by this 1660 security model cannot interact with other unix tools. "none" 1661 security model is same as passthrough except the sever won't 1662 report failures if it fails to set file attributes like 1663 ownership. Security model is mandatory only for local fsdriver. 1664 Other fsdrivers (like proxy) don't take security model as a 1665 parameter. 1666 1667 ``writeout=writeout`` 1668 This is an optional argument. The only supported value is 1669 "immediate". This means that host page cache will be used to 1670 read and write data but write notification will be sent to the 1671 guest only when the data has been reported as written by the 1672 storage subsystem. 1673 1674 ``readonly=on`` 1675 Enables exporting 9p share as a readonly mount for guests. By 1676 default read-write access is given. 1677 1678 ``socket=socket`` 1679 Enables proxy filesystem driver to use passed socket file for 1680 communicating with virtfs-proxy-helper(1). 1681 1682 ``sock_fd=sock_fd`` 1683 Enables proxy filesystem driver to use passed socket descriptor 1684 for communicating with virtfs-proxy-helper(1). Usually a helper 1685 like libvirt will create socketpair and pass one of the fds as 1686 sock\_fd. 1687 1688 ``fmode=fmode`` 1689 Specifies the default mode for newly created files on the host. 1690 Works only with security models "mapped-xattr" and 1691 "mapped-file". 1692 1693 ``dmode=dmode`` 1694 Specifies the default mode for newly created directories on the 1695 host. Works only with security models "mapped-xattr" and 1696 "mapped-file". 1697 1698 ``throttling.bps-total=b,throttling.bps-read=r,throttling.bps-write=w`` 1699 Specify bandwidth throttling limits in bytes per second, either 1700 for all request types or for reads or writes only. 1701 1702 ``throttling.bps-total-max=bm,bps-read-max=rm,bps-write-max=wm`` 1703 Specify bursts in bytes per second, either for all request types 1704 or for reads or writes only. Bursts allow the guest I/O to spike 1705 above the limit temporarily. 1706 1707 ``throttling.iops-total=i,throttling.iops-read=r, throttling.iops-write=w`` 1708 Specify request rate limits in requests per second, either for 1709 all request types or for reads or writes only. 1710 1711 ``throttling.iops-total-max=im,throttling.iops-read-max=irm, throttling.iops-write-max=iwm`` 1712 Specify bursts in requests per second, either for all request 1713 types or for reads or writes only. Bursts allow the guest I/O to 1714 spike above the limit temporarily. 1715 1716 ``throttling.iops-size=is`` 1717 Let every is bytes of a request count as a new request for iops 1718 throttling purposes. 1719 1720 -fsdev option is used along with -device driver "virtio-9p-...". 1721 1722``-device virtio-9p-type,fsdev=id,mount_tag=mount_tag`` 1723 Options for virtio-9p-... driver are: 1724 1725 ``type`` 1726 Specifies the variant to be used. Supported values are "pci", 1727 "ccw" or "device", depending on the machine type. 1728 1729 ``fsdev=id`` 1730 Specifies the id value specified along with -fsdev option. 1731 1732 ``mount_tag=mount_tag`` 1733 Specifies the tag name to be used by the guest to mount this 1734 export point. 1735ERST 1736 1737DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, 1738 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n" 1739 " [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n" 1740 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n" 1741 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n" 1742 "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n", 1743 QEMU_ARCH_ALL) 1744 1745SRST 1746``-virtfs local,path=path,mount_tag=mount_tag ,security_model=security_model[,writeout=writeout][,readonly=on] [,fmode=fmode][,dmode=dmode][,multidevs=multidevs]`` 1747 \ 1748``-virtfs proxy,socket=socket,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1749 \ 1750``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly=on]`` 1751 \ 1752``-virtfs synth,mount_tag=mount_tag`` 1753 Define a new virtual filesystem device and expose it to the guest using 1754 a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain 1755 directory on host is made directly accessible by guest as a pass-through 1756 file system by using the 9P network protocol for communication between 1757 host and guests, if desired even accessible, shared by several guests 1758 simultaniously. 1759 1760 Note that ``-virtfs`` is actually just a convenience shortcut for its 1761 generalized form ``-fsdev -device virtio-9p-pci``. 1762 1763 The general form of pass-through file system options are: 1764 1765 ``local`` 1766 Accesses to the filesystem are done by QEMU. 1767 1768 ``proxy`` 1769 Accesses to the filesystem are done by virtfs-proxy-helper(1). 1770 1771 ``synth`` 1772 Synthetic filesystem, only used by QTests. 1773 1774 ``id=id`` 1775 Specifies identifier for the filesystem device 1776 1777 ``path=path`` 1778 Specifies the export path for the file system device. Files 1779 under this path will be available to the 9p client on the guest. 1780 1781 ``security_model=security_model`` 1782 Specifies the security model to be used for this export path. 1783 Supported security models are "passthrough", "mapped-xattr", 1784 "mapped-file" and "none". In "passthrough" security model, files 1785 are stored using the same credentials as they are created on the 1786 guest. This requires QEMU to run as root. In "mapped-xattr" 1787 security model, some of the file attributes like uid, gid, mode 1788 bits and link target are stored as file attributes. For 1789 "mapped-file" these attributes are stored in the hidden 1790 .virtfs\_metadata directory. Directories exported by this 1791 security model cannot interact with other unix tools. "none" 1792 security model is same as passthrough except the sever won't 1793 report failures if it fails to set file attributes like 1794 ownership. Security model is mandatory only for local fsdriver. 1795 Other fsdrivers (like proxy) don't take security model as a 1796 parameter. 1797 1798 ``writeout=writeout`` 1799 This is an optional argument. The only supported value is 1800 "immediate". This means that host page cache will be used to 1801 read and write data but write notification will be sent to the 1802 guest only when the data has been reported as written by the 1803 storage subsystem. 1804 1805 ``readonly=on`` 1806 Enables exporting 9p share as a readonly mount for guests. By 1807 default read-write access is given. 1808 1809 ``socket=socket`` 1810 Enables proxy filesystem driver to use passed socket file for 1811 communicating with virtfs-proxy-helper(1). Usually a helper like 1812 libvirt will create socketpair and pass one of the fds as 1813 sock\_fd. 1814 1815 ``sock_fd`` 1816 Enables proxy filesystem driver to use passed 'sock\_fd' as the 1817 socket descriptor for interfacing with virtfs-proxy-helper(1). 1818 1819 ``fmode=fmode`` 1820 Specifies the default mode for newly created files on the host. 1821 Works only with security models "mapped-xattr" and 1822 "mapped-file". 1823 1824 ``dmode=dmode`` 1825 Specifies the default mode for newly created directories on the 1826 host. Works only with security models "mapped-xattr" and 1827 "mapped-file". 1828 1829 ``mount_tag=mount_tag`` 1830 Specifies the tag name to be used by the guest to mount this 1831 export point. 1832 1833 ``multidevs=multidevs`` 1834 Specifies how to deal with multiple devices being shared with a 1835 9p export. Supported behaviours are either "remap", "forbid" or 1836 "warn". The latter is the default behaviour on which virtfs 9p 1837 expects only one device to be shared with the same export, and 1838 if more than one device is shared and accessed via the same 9p 1839 export then only a warning message is logged (once) by qemu on 1840 host side. In order to avoid file ID collisions on guest you 1841 should either create a separate virtfs export for each device to 1842 be shared with guests (recommended way) or you might use "remap" 1843 instead which allows you to share multiple devices with only one 1844 export instead, which is achieved by remapping the original 1845 inode numbers from host to guest in a way that would prevent 1846 such collisions. Remapping inodes in such use cases is required 1847 because the original device IDs from host are never passed and 1848 exposed on guest. Instead all files of an export shared with 1849 virtfs always share the same device id on guest. So two files 1850 with identical inode numbers but from actually different devices 1851 on host would otherwise cause a file ID collision and hence 1852 potential misbehaviours on guest. "forbid" on the other hand 1853 assumes like "warn" that only one device is shared by the same 1854 export, however it will not only log a warning message but also 1855 deny access to additional devices on guest. Note though that 1856 "forbid" does currently not block all possible file access 1857 operations (e.g. readdir() would still return entries from other 1858 devices). 1859ERST 1860 1861DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi, 1862 "-iscsi [user=user][,password=password]\n" 1863 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n" 1864 " [,initiator-name=initiator-iqn][,id=target-iqn]\n" 1865 " [,timeout=timeout]\n" 1866 " iSCSI session parameters\n", QEMU_ARCH_ALL) 1867 1868SRST 1869``-iscsi`` 1870 Configure iSCSI session parameters. 1871ERST 1872 1873DEFHEADING() 1874 1875DEFHEADING(USB convenience options:) 1876 1877DEF("usb", 0, QEMU_OPTION_usb, 1878 "-usb enable on-board USB host controller (if not enabled by default)\n", 1879 QEMU_ARCH_ALL) 1880SRST 1881``-usb`` 1882 Enable USB emulation on machine types with an on-board USB host 1883 controller (if not enabled by default). Note that on-board USB host 1884 controllers may not support USB 3.0. In this case 1885 ``-device qemu-xhci`` can be used instead on machines with PCI. 1886ERST 1887 1888DEF("usbdevice", HAS_ARG, QEMU_OPTION_usbdevice, 1889 "-usbdevice name add the host or guest USB device 'name'\n", 1890 QEMU_ARCH_ALL) 1891SRST 1892``-usbdevice devname`` 1893 Add the USB device devname, and enable an on-board USB controller 1894 if possible and necessary (just like it can be done via 1895 ``-machine usb=on``). Note that this option is mainly intended for 1896 the user's convenience only. More fine-grained control can be 1897 achieved by selecting a USB host controller (if necessary) and the 1898 desired USB device via the ``-device`` option instead. For example, 1899 instead of using ``-usbdevice mouse`` it is possible to use 1900 ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse 1901 to a USB 3.0 controller instead (at least on machines that support 1902 PCI and do not have an USB controller enabled by default yet). 1903 For more details, see the chapter about 1904 :ref:`Connecting USB devices` in the System Emulation Users Guide. 1905 Possible devices for devname are: 1906 1907 ``braille`` 1908 Braille device. This will use BrlAPI to display the braille 1909 output on a real or fake device (i.e. it also creates a 1910 corresponding ``braille`` chardev automatically beside the 1911 ``usb-braille`` USB device). 1912 1913 ``keyboard`` 1914 Standard USB keyboard. Will override the PS/2 keyboard (if present). 1915 1916 ``mouse`` 1917 Virtual Mouse. This will override the PS/2 mouse emulation when 1918 activated. 1919 1920 ``tablet`` 1921 Pointer device that uses absolute coordinates (like a 1922 touchscreen). This means QEMU is able to report the mouse 1923 position without having to grab the mouse. Also overrides the 1924 PS/2 mouse emulation when activated. 1925 1926 ``wacom-tablet`` 1927 Wacom PenPartner USB tablet. 1928 1929 1930ERST 1931 1932DEFHEADING() 1933 1934DEFHEADING(Display options:) 1935 1936DEF("display", HAS_ARG, QEMU_OPTION_display, 1937#if defined(CONFIG_SPICE) 1938 "-display spice-app[,gl=on|off]\n" 1939#endif 1940#if defined(CONFIG_SDL) 1941 "-display sdl[,gl=on|core|es|off][,grab-mod=<mod>][,show-cursor=on|off]\n" 1942 " [,window-close=on|off]\n" 1943#endif 1944#if defined(CONFIG_GTK) 1945 "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n" 1946 " [,show-cursor=on|off][,window-close=on|off]\n" 1947#endif 1948#if defined(CONFIG_VNC) 1949 "-display vnc=<display>[,<optargs>]\n" 1950#endif 1951#if defined(CONFIG_CURSES) 1952 "-display curses[,charset=<encoding>]\n" 1953#endif 1954#if defined(CONFIG_COCOA) 1955 "-display cocoa[,full-grab=on|off][,swap-opt-cmd=on|off]\n" 1956#endif 1957#if defined(CONFIG_OPENGL) 1958 "-display egl-headless[,rendernode=<file>]\n" 1959#endif 1960#if defined(CONFIG_DBUS_DISPLAY) 1961 "-display dbus[,addr=<dbusaddr>]\n" 1962 " [,gl=on|core|es|off][,rendernode=<file>]\n" 1963#endif 1964#if defined(CONFIG_COCOA) 1965 "-display cocoa[,show-cursor=on|off][,left-command-key=on|off]\n" 1966#endif 1967 "-display none\n" 1968 " select display backend type\n" 1969 " The default display is equivalent to\n " 1970#if defined(CONFIG_GTK) 1971 "\"-display gtk\"\n" 1972#elif defined(CONFIG_SDL) 1973 "\"-display sdl\"\n" 1974#elif defined(CONFIG_COCOA) 1975 "\"-display cocoa\"\n" 1976#elif defined(CONFIG_VNC) 1977 "\"-vnc localhost:0,to=99,id=default\"\n" 1978#else 1979 "\"-display none\"\n" 1980#endif 1981 , QEMU_ARCH_ALL) 1982SRST 1983``-display type`` 1984 Select type of display to use. Use ``-display help`` to list the available 1985 display types. Valid values for type are 1986 1987 ``spice-app[,gl=on|off]`` 1988 Start QEMU as a Spice server and launch the default Spice client 1989 application. The Spice server will redirect the serial consoles 1990 and QEMU monitors. (Since 4.0) 1991 1992 ``dbus`` 1993 Export the display over D-Bus interfaces. (Since 7.0) 1994 1995 The connection is registered with the "org.qemu" name (and queued when 1996 already owned). 1997 1998 ``addr=<dbusaddr>`` : D-Bus bus address to connect to. 1999 2000 ``p2p=yes|no`` : Use peer-to-peer connection, accepted via QMP ``add_client``. 2001 2002 ``gl=on|off|core|es`` : Use OpenGL for rendering (the D-Bus interface 2003 will share framebuffers with DMABUF file descriptors). 2004 2005 ``sdl`` 2006 Display video output via SDL (usually in a separate graphics 2007 window; see the SDL documentation for other possibilities). 2008 Valid parameters are: 2009 2010 ``grab-mod=<mods>`` : Used to select the modifier keys for toggling 2011 the mouse grabbing in conjunction with the "g" key. ``<mods>`` can be 2012 either ``lshift-lctrl-lalt`` or ``rctrl``. 2013 2014 ``gl=on|off|core|es`` : Use OpenGL for displaying 2015 2016 ``show-cursor=on|off`` : Force showing the mouse cursor 2017 2018 ``window-close=on|off`` : Allow to quit qemu with window close button 2019 2020 ``gtk`` 2021 Display video output in a GTK window. This interface provides 2022 drop-down menus and other UI elements to configure and control 2023 the VM during runtime. Valid parameters are: 2024 2025 ``full-screen=on|off`` : Start in fullscreen mode 2026 2027 ``gl=on|off`` : Use OpenGL for displaying 2028 2029 ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover 2030 2031 ``show-cursor=on|off`` : Force showing the mouse cursor 2032 2033 ``window-close=on|off`` : Allow to quit qemu with window close button 2034 2035 ``curses[,charset=<encoding>]`` 2036 Display video output via curses. For graphics device models 2037 which support a text mode, QEMU can display this output using a 2038 curses/ncurses interface. Nothing is displayed when the graphics 2039 device is in graphical mode or if the graphics device does not 2040 support a text mode. Generally only the VGA device models 2041 support text mode. The font charset used by the guest can be 2042 specified with the ``charset`` option, for example 2043 ``charset=CP850`` for IBM CP850 encoding. The default is 2044 ``CP437``. 2045 2046 ``cocoa`` 2047 Display video output in a Cocoa window. Mac only. This interface 2048 provides drop-down menus and other UI elements to configure and 2049 control the VM during runtime. Valid parameters are: 2050 2051 ``show-cursor=on|off`` : Force showing the mouse cursor 2052 2053 ``left-command-key=on|off`` : Disable forwarding left command key to host 2054 2055 ``egl-headless[,rendernode=<file>]`` 2056 Offload all OpenGL operations to a local DRI device. For any 2057 graphical display, this display needs to be paired with either 2058 VNC or SPICE displays. 2059 2060 ``vnc=<display>`` 2061 Start a VNC server on display <display> 2062 2063 ``none`` 2064 Do not display video output. The guest will still see an 2065 emulated graphics card, but its output will not be displayed to 2066 the QEMU user. This option differs from the -nographic option in 2067 that it only affects what is done with video output; -nographic 2068 also changes the destination of the serial and parallel port 2069 data. 2070ERST 2071 2072DEF("nographic", 0, QEMU_OPTION_nographic, 2073 "-nographic disable graphical output and redirect serial I/Os to console\n", 2074 QEMU_ARCH_ALL) 2075SRST 2076``-nographic`` 2077 Normally, if QEMU is compiled with graphical window support, it 2078 displays output such as guest graphics, guest console, and the QEMU 2079 monitor in a window. With this option, you can totally disable 2080 graphical output so that QEMU is a simple command line application. 2081 The emulated serial port is redirected on the console and muxed with 2082 the monitor (unless redirected elsewhere explicitly). Therefore, you 2083 can still use QEMU to debug a Linux kernel with a serial console. 2084 Use C-a h for help on switching between the console and monitor. 2085ERST 2086 2087#ifdef CONFIG_SPICE 2088DEF("spice", HAS_ARG, QEMU_OPTION_spice, 2089 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n" 2090 " [,x509-key-file=<file>][,x509-key-password=<file>]\n" 2091 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n" 2092 " [,x509-dh-key-file=<file>][,addr=addr]\n" 2093 " [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n" 2094 " [,tls-ciphers=<list>]\n" 2095 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n" 2096 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n" 2097 " [,sasl=on|off][,disable-ticketing=on|off]\n" 2098 " [,password=<string>][,password-secret=<secret-id>]\n" 2099 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n" 2100 " [,jpeg-wan-compression=[auto|never|always]]\n" 2101 " [,zlib-glz-wan-compression=[auto|never|always]]\n" 2102 " [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n" 2103 " [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n" 2104 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n" 2105 " [,gl=[on|off]][,rendernode=<file>]\n" 2106 " enable spice\n" 2107 " at least one of {port, tls-port} is mandatory\n", 2108 QEMU_ARCH_ALL) 2109#endif 2110SRST 2111``-spice option[,option[,...]]`` 2112 Enable the spice remote desktop protocol. Valid options are 2113 2114 ``port=<nr>`` 2115 Set the TCP port spice is listening on for plaintext channels. 2116 2117 ``addr=<addr>`` 2118 Set the IP address spice is listening on. Default is any 2119 address. 2120 2121 ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off`` 2122 Force using the specified IP version. 2123 2124 ``password=<string>`` 2125 Set the password you need to authenticate. 2126 2127 This option is deprecated and insecure because it leaves the 2128 password visible in the process listing. Use ``password-secret`` 2129 instead. 2130 2131 ``password-secret=<secret-id>`` 2132 Set the ID of the ``secret`` object containing the password 2133 you need to authenticate. 2134 2135 ``sasl=on|off`` 2136 Require that the client use SASL to authenticate with the spice. 2137 The exact choice of authentication method used is controlled 2138 from the system / user's SASL configuration file for the 'qemu' 2139 service. This is typically found in /etc/sasl2/qemu.conf. If 2140 running QEMU as an unprivileged user, an environment variable 2141 SASL\_CONF\_PATH can be used to make it search alternate 2142 locations for the service config. While some SASL auth methods 2143 can also provide data encryption (eg GSSAPI), it is recommended 2144 that SASL always be combined with the 'tls' and 'x509' settings 2145 to enable use of SSL and server certificates. This ensures a 2146 data encryption preventing compromise of authentication 2147 credentials. 2148 2149 ``disable-ticketing=on|off`` 2150 Allow client connects without authentication. 2151 2152 ``disable-copy-paste=on|off`` 2153 Disable copy paste between the client and the guest. 2154 2155 ``disable-agent-file-xfer=on|off`` 2156 Disable spice-vdagent based file-xfer between the client and the 2157 guest. 2158 2159 ``tls-port=<nr>`` 2160 Set the TCP port spice is listening on for encrypted channels. 2161 2162 ``x509-dir=<dir>`` 2163 Set the x509 file directory. Expects same filenames as -vnc 2164 $display,x509=$dir 2165 2166 ``x509-key-file=<file>``; \ ``x509-key-password=<file>``; \ ``x509-cert-file=<file>``; \ ``x509-cacert-file=<file>``; \ ``x509-dh-key-file=<file>`` 2167 The x509 file names can also be configured individually. 2168 2169 ``tls-ciphers=<list>`` 2170 Specify which ciphers to use. 2171 2172 ``tls-channel=[main|display|cursor|inputs|record|playback]``; \ ``plaintext-channel=[main|display|cursor|inputs|record|playback]`` 2173 Force specific channel to be used with or without TLS 2174 encryption. The options can be specified multiple times to 2175 configure multiple channels. The special name "default" can be 2176 used to set the default mode. For channels which are not 2177 explicitly forced into one mode the spice client is allowed to 2178 pick tls/plaintext as he pleases. 2179 2180 ``image-compression=[auto_glz|auto_lz|quic|glz|lz|off]`` 2181 Configure image compression (lossless). Default is auto\_glz. 2182 2183 ``jpeg-wan-compression=[auto|never|always]``; \ ``zlib-glz-wan-compression=[auto|never|always]`` 2184 Configure wan image compression (lossy for slow links). Default 2185 is auto. 2186 2187 ``streaming-video=[off|all|filter]`` 2188 Configure video stream detection. Default is off. 2189 2190 ``agent-mouse=[on|off]`` 2191 Enable/disable passing mouse events via vdagent. Default is on. 2192 2193 ``playback-compression=[on|off]`` 2194 Enable/disable audio stream compression (using celt 0.5.1). 2195 Default is on. 2196 2197 ``seamless-migration=[on|off]`` 2198 Enable/disable spice seamless migration. Default is off. 2199 2200 ``gl=[on|off]`` 2201 Enable/disable OpenGL context. Default is off. 2202 2203 ``rendernode=<file>`` 2204 DRM render node for OpenGL rendering. If not specified, it will 2205 pick the first available. (Since 2.9) 2206ERST 2207 2208DEF("portrait", 0, QEMU_OPTION_portrait, 2209 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n", 2210 QEMU_ARCH_ALL) 2211SRST 2212``-portrait`` 2213 Rotate graphical output 90 deg left (only PXA LCD). 2214ERST 2215 2216DEF("rotate", HAS_ARG, QEMU_OPTION_rotate, 2217 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n", 2218 QEMU_ARCH_ALL) 2219SRST 2220``-rotate deg`` 2221 Rotate graphical output some deg left (only PXA LCD). 2222ERST 2223 2224DEF("vga", HAS_ARG, QEMU_OPTION_vga, 2225 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n" 2226 " select video card type\n", QEMU_ARCH_ALL) 2227SRST 2228``-vga type`` 2229 Select type of VGA card to emulate. Valid values for type are 2230 2231 ``cirrus`` 2232 Cirrus Logic GD5446 Video card. All Windows versions starting 2233 from Windows 95 should recognize and use this graphic card. For 2234 optimal performances, use 16 bit color depth in the guest and 2235 the host OS. (This card was the default before QEMU 2.2) 2236 2237 ``std`` 2238 Standard VGA card with Bochs VBE extensions. If your guest OS 2239 supports the VESA 2.0 VBE extensions (e.g. Windows XP) and if 2240 you want to use high resolution modes (>= 1280x1024x16) then you 2241 should use this option. (This card is the default since QEMU 2242 2.2) 2243 2244 ``vmware`` 2245 VMWare SVGA-II compatible adapter. Use it if you have 2246 sufficiently recent XFree86/XOrg server or Windows guest with a 2247 driver for this card. 2248 2249 ``qxl`` 2250 QXL paravirtual graphic card. It is VGA compatible (including 2251 VESA 2.0 VBE support). Works best with qxl guest drivers 2252 installed though. Recommended choice when using the spice 2253 protocol. 2254 2255 ``tcx`` 2256 (sun4m only) Sun TCX framebuffer. This is the default 2257 framebuffer for sun4m machines and offers both 8-bit and 24-bit 2258 colour depths at a fixed resolution of 1024x768. 2259 2260 ``cg3`` 2261 (sun4m only) Sun cgthree framebuffer. This is a simple 8-bit 2262 framebuffer for sun4m machines available in both 1024x768 2263 (OpenBIOS) and 1152x900 (OBP) resolutions aimed at people 2264 wishing to run older Solaris versions. 2265 2266 ``virtio`` 2267 Virtio VGA card. 2268 2269 ``none`` 2270 Disable VGA card. 2271ERST 2272 2273DEF("full-screen", 0, QEMU_OPTION_full_screen, 2274 "-full-screen start in full screen\n", QEMU_ARCH_ALL) 2275SRST 2276``-full-screen`` 2277 Start in full screen. 2278ERST 2279 2280DEF("g", HAS_ARG, QEMU_OPTION_g , 2281 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n", 2282 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K) 2283SRST 2284``-g`` *width*\ ``x``\ *height*\ ``[x``\ *depth*\ ``]`` 2285 Set the initial graphical resolution and depth (PPC, SPARC only). 2286 2287 For PPC the default is 800x600x32. 2288 2289 For SPARC with the TCX graphics device, the default is 1024x768x8 2290 with the option of 1024x768x24. For cgthree, the default is 2291 1024x768x8 with the option of 1152x900x8 for people who wish to use 2292 OBP. 2293ERST 2294 2295DEF("vnc", HAS_ARG, QEMU_OPTION_vnc , 2296 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL) 2297SRST 2298``-vnc display[,option[,option[,...]]]`` 2299 Normally, if QEMU is compiled with graphical window support, it 2300 displays output such as guest graphics, guest console, and the QEMU 2301 monitor in a window. With this option, you can have QEMU listen on 2302 VNC display display and redirect the VGA display over the VNC 2303 session. It is very useful to enable the usb tablet device when 2304 using this option (option ``-device usb-tablet``). When using the 2305 VNC display, you must use the ``-k`` parameter to set the keyboard 2306 layout if you are not using en-us. Valid syntax for the display is 2307 2308 ``to=L`` 2309 With this option, QEMU will try next available VNC displays, 2310 until the number L, if the origianlly defined "-vnc display" is 2311 not available, e.g. port 5900+display is already used by another 2312 application. By default, to=0. 2313 2314 ``host:d`` 2315 TCP connections will only be allowed from host on display d. By 2316 convention the TCP port is 5900+d. Optionally, host can be 2317 omitted in which case the server will accept connections from 2318 any host. 2319 2320 ``unix:path`` 2321 Connections will be allowed over UNIX domain sockets where path 2322 is the location of a unix socket to listen for connections on. 2323 2324 ``none`` 2325 VNC is initialized but not started. The monitor ``change`` 2326 command can be used to later start the VNC server. 2327 2328 Following the display value there may be one or more option flags 2329 separated by commas. Valid options are 2330 2331 ``reverse=on|off`` 2332 Connect to a listening VNC client via a "reverse" connection. 2333 The client is specified by the display. For reverse network 2334 connections (host:d,``reverse``), the d argument is a TCP port 2335 number, not a display number. 2336 2337 ``websocket=on|off`` 2338 Opens an additional TCP listening port dedicated to VNC 2339 Websocket connections. If a bare websocket option is given, the 2340 Websocket port is 5700+display. An alternative port can be 2341 specified with the syntax ``websocket``\ =port. 2342 2343 If host is specified connections will only be allowed from this 2344 host. It is possible to control the websocket listen address 2345 independently, using the syntax ``websocket``\ =host:port. 2346 2347 If no TLS credentials are provided, the websocket connection 2348 runs in unencrypted mode. If TLS credentials are provided, the 2349 websocket connection requires encrypted client connections. 2350 2351 ``password=on|off`` 2352 Require that password based authentication is used for client 2353 connections. 2354 2355 The password must be set separately using the ``set_password`` 2356 command in the :ref:`QEMU monitor`. The 2357 syntax to change your password is: 2358 ``set_password <protocol> <password>`` where <protocol> could be 2359 either "vnc" or "spice". 2360 2361 If you would like to change <protocol> password expiration, you 2362 should use ``expire_password <protocol> <expiration-time>`` 2363 where expiration time could be one of the following options: 2364 now, never, +seconds or UNIX time of expiration, e.g. +60 to 2365 make password expire in 60 seconds, or 1335196800 to make 2366 password expire on "Mon Apr 23 12:00:00 EDT 2012" (UNIX time for 2367 this date and time). 2368 2369 You can also use keywords "now" or "never" for the expiration 2370 time to allow <protocol> password to expire immediately or never 2371 expire. 2372 2373 ``password-secret=<secret-id>`` 2374 Require that password based authentication is used for client 2375 connections, using the password provided by the ``secret`` 2376 object identified by ``secret-id``. 2377 2378 ``tls-creds=ID`` 2379 Provides the ID of a set of TLS credentials to use to secure the 2380 VNC server. They will apply to both the normal VNC server socket 2381 and the websocket socket (if enabled). Setting TLS credentials 2382 will cause the VNC server socket to enable the VeNCrypt auth 2383 mechanism. The credentials should have been previously created 2384 using the ``-object tls-creds`` argument. 2385 2386 ``tls-authz=ID`` 2387 Provides the ID of the QAuthZ authorization object against which 2388 the client's x509 distinguished name will validated. This object 2389 is only resolved at time of use, so can be deleted and recreated 2390 on the fly while the VNC server is active. If missing, it will 2391 default to denying access. 2392 2393 ``sasl=on|off`` 2394 Require that the client use SASL to authenticate with the VNC 2395 server. The exact choice of authentication method used is 2396 controlled from the system / user's SASL configuration file for 2397 the 'qemu' service. This is typically found in 2398 /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, 2399 an environment variable SASL\_CONF\_PATH can be used to make it 2400 search alternate locations for the service config. While some 2401 SASL auth methods can also provide data encryption (eg GSSAPI), 2402 it is recommended that SASL always be combined with the 'tls' 2403 and 'x509' settings to enable use of SSL and server 2404 certificates. This ensures a data encryption preventing 2405 compromise of authentication credentials. See the 2406 :ref:`VNC security` section in the System Emulation Users Guide 2407 for details on using SASL authentication. 2408 2409 ``sasl-authz=ID`` 2410 Provides the ID of the QAuthZ authorization object against which 2411 the client's SASL username will validated. This object is only 2412 resolved at time of use, so can be deleted and recreated on the 2413 fly while the VNC server is active. If missing, it will default 2414 to denying access. 2415 2416 ``acl=on|off`` 2417 Legacy method for enabling authorization of clients against the 2418 x509 distinguished name and SASL username. It results in the 2419 creation of two ``authz-list`` objects with IDs of 2420 ``vnc.username`` and ``vnc.x509dname``. The rules for these 2421 objects must be configured with the HMP ACL commands. 2422 2423 This option is deprecated and should no longer be used. The new 2424 ``sasl-authz`` and ``tls-authz`` options are a replacement. 2425 2426 ``lossy=on|off`` 2427 Enable lossy compression methods (gradient, JPEG, ...). If this 2428 option is set, VNC client may receive lossy framebuffer updates 2429 depending on its encoding settings. Enabling this option can 2430 save a lot of bandwidth at the expense of quality. 2431 2432 ``non-adaptive=on|off`` 2433 Disable adaptive encodings. Adaptive encodings are enabled by 2434 default. An adaptive encoding will try to detect frequently 2435 updated screen regions, and send updates in these regions using 2436 a lossy encoding (like JPEG). This can be really helpful to save 2437 bandwidth when playing videos. Disabling adaptive encodings 2438 restores the original static behavior of encodings like Tight. 2439 2440 ``share=[allow-exclusive|force-shared|ignore]`` 2441 Set display sharing policy. 'allow-exclusive' allows clients to 2442 ask for exclusive access. As suggested by the rfb spec this is 2443 implemented by dropping other connections. Connecting multiple 2444 clients in parallel requires all clients asking for a shared 2445 session (vncviewer: -shared switch). This is the default. 2446 'force-shared' disables exclusive client access. Useful for 2447 shared desktop sessions, where you don't want someone forgetting 2448 specify -shared disconnect everybody else. 'ignore' completely 2449 ignores the shared flag and allows everybody connect 2450 unconditionally. Doesn't conform to the rfb spec but is 2451 traditional QEMU behavior. 2452 2453 ``key-delay-ms`` 2454 Set keyboard delay, for key down and key up events, in 2455 milliseconds. Default is 10. Keyboards are low-bandwidth 2456 devices, so this slowdown can help the device and guest to keep 2457 up and not lose events in case events are arriving in bulk. 2458 Possible causes for the latter are flaky network connections, or 2459 scripts for automated testing. 2460 2461 ``audiodev=audiodev`` 2462 Use the specified audiodev when the VNC client requests audio 2463 transmission. When not using an -audiodev argument, this option 2464 must be omitted, otherwise is must be present and specify a 2465 valid audiodev. 2466 2467 ``power-control=on|off`` 2468 Permit the remote client to issue shutdown, reboot or reset power 2469 control requests. 2470ERST 2471 2472ARCHHEADING(, QEMU_ARCH_I386) 2473 2474ARCHHEADING(i386 target only:, QEMU_ARCH_I386) 2475 2476DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack, 2477 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n", 2478 QEMU_ARCH_I386) 2479SRST 2480``-win2k-hack`` 2481 Use it when installing Windows 2000 to avoid a disk full bug. After 2482 Windows 2000 is installed, you no longer need this option (this 2483 option slows down the IDE transfers). 2484ERST 2485 2486DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk, 2487 "-no-fd-bootchk disable boot signature checking for floppy disks\n", 2488 QEMU_ARCH_I386) 2489SRST 2490``-no-fd-bootchk`` 2491 Disable boot signature checking for floppy disks in BIOS. May be 2492 needed to boot from old floppy disks. 2493ERST 2494 2495DEF("no-acpi", 0, QEMU_OPTION_no_acpi, 2496 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2497SRST 2498``-no-acpi`` 2499 Disable ACPI (Advanced Configuration and Power Interface) support. 2500 Use it if your guest OS complains about ACPI problems (PC target 2501 machine only). 2502ERST 2503 2504DEF("no-hpet", 0, QEMU_OPTION_no_hpet, 2505 "-no-hpet disable HPET\n", QEMU_ARCH_I386) 2506SRST 2507``-no-hpet`` 2508 Disable HPET support. 2509ERST 2510 2511DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable, 2512 "-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" 2513 " ACPI table description\n", QEMU_ARCH_I386) 2514SRST 2515``-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]...]`` 2516 Add ACPI table with specified header fields and context from 2517 specified files. For file=, take whole ACPI table from the specified 2518 files, including all ACPI headers (possible overridden by other 2519 options). For data=, only data portion of the table is used, all 2520 header information is specified in the command line. If a SLIC table 2521 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id 2522 fields will override the same in the RSDT and the FADT (a.k.a. 2523 FACP), in order to ensure the field matches required by the 2524 Microsoft SLIC spec and the ACPI spec. 2525ERST 2526 2527DEF("smbios", HAS_ARG, QEMU_OPTION_smbios, 2528 "-smbios file=binary\n" 2529 " load SMBIOS entry from binary file\n" 2530 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n" 2531 " [,uefi=on|off]\n" 2532 " specify SMBIOS type 0 fields\n" 2533 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2534 " [,uuid=uuid][,sku=str][,family=str]\n" 2535 " specify SMBIOS type 1 fields\n" 2536 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n" 2537 " [,asset=str][,location=str]\n" 2538 " specify SMBIOS type 2 fields\n" 2539 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n" 2540 " [,sku=str]\n" 2541 " specify SMBIOS type 3 fields\n" 2542 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n" 2543 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n" 2544 " [,processor-id=%d]\n" 2545 " specify SMBIOS type 4 fields\n" 2546 "-smbios type=11[,value=str][,path=filename]\n" 2547 " specify SMBIOS type 11 fields\n" 2548 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n" 2549 " [,asset=str][,part=str][,speed=%d]\n" 2550 " specify SMBIOS type 17 fields\n" 2551 "-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]\n" 2552 " specify SMBIOS type 41 fields\n", 2553 QEMU_ARCH_I386 | QEMU_ARCH_ARM) 2554SRST 2555``-smbios file=binary`` 2556 Load SMBIOS entry from binary file. 2557 2558``-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d][,uefi=on|off]`` 2559 Specify SMBIOS type 0 fields 2560 2561``-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str][,uuid=uuid][,sku=str][,family=str]`` 2562 Specify SMBIOS type 1 fields 2563 2564``-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str][,asset=str][,location=str]`` 2565 Specify SMBIOS type 2 fields 2566 2567``-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str][,sku=str]`` 2568 Specify SMBIOS type 3 fields 2569 2570``-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str][,asset=str][,part=str][,processor-id=%d]`` 2571 Specify SMBIOS type 4 fields 2572 2573``-smbios type=11[,value=str][,path=filename]`` 2574 Specify SMBIOS type 11 fields 2575 2576 This argument can be repeated multiple times, and values are added in the order they are parsed. 2577 Applications intending to use OEM strings data are encouraged to use their application name as 2578 a prefix for the value string. This facilitates passing information for multiple applications 2579 concurrently. 2580 2581 The ``value=str`` syntax provides the string data inline, while the ``path=filename`` syntax 2582 loads data from a file on disk. Note that the file is not permitted to contain any NUL bytes. 2583 2584 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to 2585 the SMBIOS table in the order in which they appear. 2586 2587 Note that on the x86 architecture, the total size of all SMBIOS tables is limited to 65535 2588 bytes. Thus the OEM strings data is not suitable for passing large amounts of data into the 2589 guest. Instead it should be used as a indicator to inform the guest where to locate the real 2590 data set, for example, by specifying the serial ID of a block device. 2591 2592 An example passing three strings is 2593 2594 .. parsed-literal:: 2595 2596 -smbios type=11,value=cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/,\\ 2597 value=anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\ 2598 path=/some/file/with/oemstringsdata.txt 2599 2600 In the guest OS this is visible with the ``dmidecode`` command 2601 2602 .. parsed-literal:: 2603 2604 $ dmidecode -t 11 2605 Handle 0x0E00, DMI type 11, 5 bytes 2606 OEM Strings 2607 String 1: cloud-init:ds=nocloud-net;s=http://10.10.0.1:8000/ 2608 String 2: anaconda:method=http://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os 2609 String 3: myapp:some extra data 2610 2611 2612``-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str][,asset=str][,part=str][,speed=%d]`` 2613 Specify SMBIOS type 17 fields 2614 2615``-smbios type=41[,designation=str][,kind=str][,instance=%d][,pcidev=str]`` 2616 Specify SMBIOS type 41 fields 2617 2618 This argument can be repeated multiple times. Its main use is to allow network interfaces be created 2619 as ``enoX`` on Linux, with X being the instance number, instead of the name depending on the interface 2620 position on the PCI bus. 2621 2622 Here is an example of use: 2623 2624 .. parsed-literal:: 2625 2626 -netdev user,id=internet \\ 2627 -device virtio-net-pci,mac=50:54:00:00:00:42,netdev=internet,id=internet-dev \\ 2628 -smbios type=41,designation='Onboard LAN',instance=1,kind=ethernet,pcidev=internet-dev 2629 2630 In the guest OS, the device should then appear as ``eno1``: 2631 2632 ..parsed-literal:: 2633 2634 $ ip -brief l 2635 lo UNKNOWN 00:00:00:00:00:00 <LOOPBACK,UP,LOWER_UP> 2636 eno1 UP 50:54:00:00:00:42 <BROADCAST,MULTICAST,UP,LOWER_UP> 2637 2638 Currently, the PCI device has to be attached to the root bus. 2639 2640ERST 2641 2642DEFHEADING() 2643 2644DEFHEADING(Network options:) 2645 2646DEF("netdev", HAS_ARG, QEMU_OPTION_netdev, 2647#ifdef CONFIG_SLIRP 2648 "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n" 2649 " [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n" 2650 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n" 2651 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n" 2652 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]" 2653#ifndef _WIN32 2654 "[,smb=dir[,smbserver=addr]]\n" 2655#endif 2656 " configure a user mode network backend with ID 'str',\n" 2657 " its DHCP server and optional services\n" 2658#endif 2659#ifdef _WIN32 2660 "-netdev tap,id=str,ifname=name\n" 2661 " configure a host TAP network backend with ID 'str'\n" 2662#else 2663 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n" 2664 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n" 2665 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n" 2666 " [,poll-us=n]\n" 2667 " configure a host TAP network backend with ID 'str'\n" 2668 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2669 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n" 2670 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n" 2671 " to deconfigure it\n" 2672 " use '[down]script=no' to disable script execution\n" 2673 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER ") to\n" 2674 " configure it\n" 2675 " use 'fd=h' to connect to an already opened TAP interface\n" 2676 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n" 2677 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n" 2678 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n" 2679 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" 2680 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" 2681 " use vhost=on to enable experimental in kernel accelerator\n" 2682 " (only has effect for virtio guests which use MSIX)\n" 2683 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" 2684 " use 'vhostfd=h' to connect to an already opened vhost net device\n" 2685 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n" 2686 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n" 2687 " use 'poll-us=n' to specify the maximum number of microseconds that could be\n" 2688 " spent on busy polling for vhost net\n" 2689 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n" 2690 " configure a host TAP network backend with ID 'str' that is\n" 2691 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE ")\n" 2692 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER ")\n" 2693#endif 2694#ifdef __linux__ 2695 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n" 2696 " [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n" 2697 " [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n" 2698 " [,rxcookie=rxcookie][,offset=offset]\n" 2699 " configure a network backend with ID 'str' connected to\n" 2700 " an Ethernet over L2TPv3 pseudowire.\n" 2701 " Linux kernel 3.3+ as well as most routers can talk\n" 2702 " L2TPv3. This transport allows connecting a VM to a VM,\n" 2703 " VM to a router and even VM to Host. It is a nearly-universal\n" 2704 " standard (RFC3931). Note - this implementation uses static\n" 2705 " pre-configured tunnels (same as the Linux kernel).\n" 2706 " use 'src=' to specify source address\n" 2707 " use 'dst=' to specify destination address\n" 2708 " use 'udp=on' to specify udp encapsulation\n" 2709 " use 'srcport=' to specify source udp port\n" 2710 " use 'dstport=' to specify destination udp port\n" 2711 " use 'ipv6=on' to force v6\n" 2712 " L2TPv3 uses cookies to prevent misconfiguration as\n" 2713 " well as a weak security measure\n" 2714 " use 'rxcookie=0x012345678' to specify a rxcookie\n" 2715 " use 'txcookie=0x012345678' to specify a txcookie\n" 2716 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n" 2717 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n" 2718 " use 'pincounter=on' to work around broken counter handling in peer\n" 2719 " use 'offset=X' to add an extra offset between header and data\n" 2720#endif 2721 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n" 2722 " configure a network backend to connect to another network\n" 2723 " using a socket connection\n" 2724 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n" 2725 " configure a network backend to connect to a multicast maddr and port\n" 2726 " use 'localaddr=addr' to specify the host address to send packets from\n" 2727 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n" 2728 " configure a network backend to connect to another network\n" 2729 " using an UDP tunnel\n" 2730#ifdef CONFIG_VDE 2731 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n" 2732 " configure a network backend to connect to port 'n' of a vde switch\n" 2733 " running on host and listening for incoming connections on 'socketpath'.\n" 2734 " Use group 'groupname' and mode 'octalmode' to change default\n" 2735 " ownership and permissions for communication port.\n" 2736#endif 2737#ifdef CONFIG_NETMAP 2738 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n" 2739 " attach to the existing netmap-enabled network interface 'name', or to a\n" 2740 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n" 2741 " netmap device, defaults to '/dev/netmap')\n" 2742#endif 2743#ifdef CONFIG_POSIX 2744 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n" 2745 " configure a vhost-user network, backed by a chardev 'dev'\n" 2746#endif 2747#ifdef __linux__ 2748 "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n" 2749 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n" 2750#endif 2751#ifdef CONFIG_VMNET 2752 "-netdev vmnet-host,id=str[,isolated=on|off][,net-uuid=uuid]\n" 2753 " [,start-address=addr,end-address=addr,subnet-mask=mask]\n" 2754 " configure a vmnet network backend in host mode with ID 'str',\n" 2755 " isolate this interface from others with 'isolated',\n" 2756 " configure the address range and choose a subnet mask,\n" 2757 " specify network UUID 'uuid' to disable DHCP and interact with\n" 2758 " vmnet-host interfaces within this isolated network\n" 2759 "-netdev vmnet-shared,id=str[,isolated=on|off][,nat66-prefix=addr]\n" 2760 " [,start-address=addr,end-address=addr,subnet-mask=mask]\n" 2761 " configure a vmnet network backend in shared mode with ID 'str',\n" 2762 " configure the address range and choose a subnet mask,\n" 2763 " set IPv6 ULA prefix (of length 64) to use for internal network,\n" 2764 " isolate this interface from others with 'isolated'\n" 2765 "-netdev vmnet-bridged,id=str,ifname=name[,isolated=on|off]\n" 2766 " configure a vmnet network backend in bridged mode with ID 'str',\n" 2767 " use 'ifname=name' to select a physical network interface to be bridged,\n" 2768 " isolate this interface from others with 'isolated'\n" 2769#endif 2770 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n" 2771 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL) 2772DEF("nic", HAS_ARG, QEMU_OPTION_nic, 2773 "-nic [tap|bridge|" 2774#ifdef CONFIG_SLIRP 2775 "user|" 2776#endif 2777#ifdef __linux__ 2778 "l2tpv3|" 2779#endif 2780#ifdef CONFIG_VDE 2781 "vde|" 2782#endif 2783#ifdef CONFIG_NETMAP 2784 "netmap|" 2785#endif 2786#ifdef CONFIG_POSIX 2787 "vhost-user|" 2788#endif 2789#ifdef CONFIG_VMNET 2790 "vmnet-host|vmnet-shared|vmnet-bridged|" 2791#endif 2792 "socket][,option][,...][mac=macaddr]\n" 2793 " initialize an on-board / default host NIC (using MAC address\n" 2794 " macaddr) and connect it to the given host network backend\n" 2795 "-nic none use it alone to have zero network devices (the default is to\n" 2796 " provided a 'user' network connection)\n", 2797 QEMU_ARCH_ALL) 2798DEF("net", HAS_ARG, QEMU_OPTION_net, 2799 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n" 2800 " configure or create an on-board (or machine default) NIC and\n" 2801 " connect it to hub 0 (please use -nic unless you need a hub)\n" 2802 "-net [" 2803#ifdef CONFIG_SLIRP 2804 "user|" 2805#endif 2806 "tap|" 2807 "bridge|" 2808#ifdef CONFIG_VDE 2809 "vde|" 2810#endif 2811#ifdef CONFIG_NETMAP 2812 "netmap|" 2813#endif 2814#ifdef CONFIG_VMNET 2815 "vmnet-host|vmnet-shared|vmnet-bridged|" 2816#endif 2817 "socket][,option][,option][,...]\n" 2818 " old way to initialize a host network interface\n" 2819 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL) 2820SRST 2821``-nic [tap|bridge|user|l2tpv3|vde|netmap|vhost-user|socket][,...][,mac=macaddr][,model=mn]`` 2822 This option is a shortcut for configuring both the on-board 2823 (default) guest NIC hardware and the host network backend in one go. 2824 The host backend options are the same as with the corresponding 2825 ``-netdev`` options below. The guest NIC model can be set with 2826 ``model=modelname``. Use ``model=help`` to list the available device 2827 types. The hardware MAC address can be set with ``mac=macaddr``. 2828 2829 The following two example do exactly the same, to show how ``-nic`` 2830 can be used to shorten the command line length: 2831 2832 .. parsed-literal:: 2833 2834 |qemu_system| -netdev user,id=n1,ipv6=off -device e1000,netdev=n1,mac=52:54:98:76:54:32 2835 |qemu_system| -nic user,ipv6=off,model=e1000,mac=52:54:98:76:54:32 2836 2837``-nic none`` 2838 Indicate that no network devices should be configured. It is used to 2839 override the default configuration (default NIC with "user" host 2840 network backend) which is activated if no other networking options 2841 are provided. 2842 2843``-netdev user,id=id[,option][,option][,...]`` 2844 Configure user mode host network backend which requires no 2845 administrator privilege to run. Valid options are: 2846 2847 ``id=id`` 2848 Assign symbolic name for use in monitor commands. 2849 2850 ``ipv4=on|off and ipv6=on|off`` 2851 Specify that either IPv4 or IPv6 must be enabled. If neither is 2852 specified both protocols are enabled. 2853 2854 ``net=addr[/mask]`` 2855 Set IP network address the guest will see. Optionally specify 2856 the netmask, either in the form a.b.c.d or as number of valid 2857 top-most bits. Default is 10.0.2.0/24. 2858 2859 ``host=addr`` 2860 Specify the guest-visible address of the host. Default is the 2861 2nd IP in the guest network, i.e. x.x.x.2. 2862 2863 ``ipv6-net=addr[/int]`` 2864 Set IPv6 network address the guest will see (default is 2865 fec0::/64). The network prefix is given in the usual hexadecimal 2866 IPv6 address notation. The prefix size is optional, and is given 2867 as the number of valid top-most bits (default is 64). 2868 2869 ``ipv6-host=addr`` 2870 Specify the guest-visible IPv6 address of the host. Default is 2871 the 2nd IPv6 in the guest network, i.e. xxxx::2. 2872 2873 ``restrict=on|off`` 2874 If this option is enabled, the guest will be isolated, i.e. it 2875 will not be able to contact the host and no guest IP packets 2876 will be routed over the host to the outside. This option does 2877 not affect any explicitly set forwarding rules. 2878 2879 ``hostname=name`` 2880 Specifies the client hostname reported by the built-in DHCP 2881 server. 2882 2883 ``dhcpstart=addr`` 2884 Specify the first of the 16 IPs the built-in DHCP server can 2885 assign. Default is the 15th to 31st IP in the guest network, 2886 i.e. x.x.x.15 to x.x.x.31. 2887 2888 ``dns=addr`` 2889 Specify the guest-visible address of the virtual nameserver. The 2890 address must be different from the host address. Default is the 2891 3rd IP in the guest network, i.e. x.x.x.3. 2892 2893 ``ipv6-dns=addr`` 2894 Specify the guest-visible address of the IPv6 virtual 2895 nameserver. The address must be different from the host address. 2896 Default is the 3rd IP in the guest network, i.e. xxxx::3. 2897 2898 ``dnssearch=domain`` 2899 Provides an entry for the domain-search list sent by the 2900 built-in DHCP server. More than one domain suffix can be 2901 transmitted by specifying this option multiple times. If 2902 supported, this will cause the guest to automatically try to 2903 append the given domain suffix(es) in case a domain name can not 2904 be resolved. 2905 2906 Example: 2907 2908 .. parsed-literal:: 2909 2910 |qemu_system| -nic user,dnssearch=mgmt.example.org,dnssearch=example.org 2911 2912 ``domainname=domain`` 2913 Specifies the client domain name reported by the built-in DHCP 2914 server. 2915 2916 ``tftp=dir`` 2917 When using the user mode network stack, activate a built-in TFTP 2918 server. The files in dir will be exposed as the root of a TFTP 2919 server. The TFTP client on the guest must be configured in 2920 binary mode (use the command ``bin`` of the Unix TFTP client). 2921 2922 ``tftp-server-name=name`` 2923 In BOOTP reply, broadcast name as the "TFTP server name" 2924 (RFC2132 option 66). This can be used to advise the guest to 2925 load boot files or configurations from a different server than 2926 the host address. 2927 2928 ``bootfile=file`` 2929 When using the user mode network stack, broadcast file as the 2930 BOOTP filename. In conjunction with ``tftp``, this can be used 2931 to network boot a guest from a local directory. 2932 2933 Example (using pxelinux): 2934 2935 .. parsed-literal:: 2936 2937 |qemu_system| -hda linux.img -boot n -device e1000,netdev=n1 \\ 2938 -netdev user,id=n1,tftp=/path/to/tftp/files,bootfile=/pxelinux.0 2939 2940 ``smb=dir[,smbserver=addr]`` 2941 When using the user mode network stack, activate a built-in SMB 2942 server so that Windows OSes can access to the host files in 2943 ``dir`` transparently. The IP address of the SMB server can be 2944 set to addr. By default the 4th IP in the guest network is used, 2945 i.e. x.x.x.4. 2946 2947 In the guest Windows OS, the line: 2948 2949 :: 2950 2951 10.0.2.4 smbserver 2952 2953 must be added in the file ``C:\WINDOWS\LMHOSTS`` (for windows 2954 9x/Me) or ``C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS`` (Windows 2955 NT/2000). 2956 2957 Then ``dir`` can be accessed in ``\\smbserver\qemu``. 2958 2959 Note that a SAMBA server must be installed on the host OS. 2960 2961 ``hostfwd=[tcp|udp]:[hostaddr]:hostport-[guestaddr]:guestport`` 2962 Redirect incoming TCP or UDP connections to the host port 2963 hostport to the guest IP address guestaddr on guest port 2964 guestport. If guestaddr is not specified, its value is x.x.x.15 2965 (default first address given by the built-in DHCP server). By 2966 specifying hostaddr, the rule can be bound to a specific host 2967 interface. If no connection type is set, TCP is used. This 2968 option can be given multiple times. 2969 2970 For example, to redirect host X11 connection from screen 1 to 2971 guest screen 0, use the following: 2972 2973 .. parsed-literal:: 2974 2975 # on the host 2976 |qemu_system| -nic user,hostfwd=tcp:127.0.0.1:6001-:6000 2977 # this host xterm should open in the guest X11 server 2978 xterm -display :1 2979 2980 To redirect telnet connections from host port 5555 to telnet 2981 port on the guest, use the following: 2982 2983 .. parsed-literal:: 2984 2985 # on the host 2986 |qemu_system| -nic user,hostfwd=tcp::5555-:23 2987 telnet localhost 5555 2988 2989 Then when you use on the host ``telnet localhost 5555``, you 2990 connect to the guest telnet server. 2991 2992 ``guestfwd=[tcp]:server:port-dev``; \ ``guestfwd=[tcp]:server:port-cmd:command`` 2993 Forward guest TCP connections to the IP address server on port 2994 port to the character device dev or to a program executed by 2995 cmd:command which gets spawned for each connection. This option 2996 can be given multiple times. 2997 2998 You can either use a chardev directly and have that one used 2999 throughout QEMU's lifetime, like in the following example: 3000 3001 .. parsed-literal:: 3002 3003 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever 3004 # the guest accesses it 3005 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321 3006 3007 Or you can execute a command on every TCP connection established 3008 by the guest, so that QEMU behaves similar to an inetd process 3009 for that virtual server: 3010 3011 .. parsed-literal:: 3012 3013 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234 3014 # and connect the TCP stream to its stdin/stdout 3015 |qemu_system| -nic 'user,id=n1,guestfwd=tcp:10.0.2.100:1234-cmd:netcat 10.10.1.1 4321' 3016 3017``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]`` 3018 Configure a host TAP network backend with ID id. 3019 3020 Use the network script file to configure it and the network script 3021 dfile to deconfigure it. If name is not provided, the OS 3022 automatically provides one. The default network configure script is 3023 ``/etc/qemu-ifup`` and the default network deconfigure script is 3024 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to 3025 disable script execution. 3026 3027 If running QEMU as an unprivileged user, use the network helper 3028 to configure the TAP interface and attach it to the bridge. 3029 The default network helper executable is 3030 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3031 ``br0``. 3032 3033 ``fd``\ =h can be used to specify the handle of an already opened 3034 host TAP interface. 3035 3036 Examples: 3037 3038 .. parsed-literal:: 3039 3040 #launch a QEMU instance with the default network script 3041 |qemu_system| linux.img -nic tap 3042 3043 .. parsed-literal:: 3044 3045 #launch a QEMU instance with two NICs, each one connected 3046 #to a TAP device 3047 |qemu_system| linux.img \\ 3048 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\ 3049 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1 3050 3051 .. parsed-literal:: 3052 3053 #launch a QEMU instance with the default network helper to 3054 #connect a TAP device to bridge br0 3055 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\ 3056 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper" 3057 3058``-netdev bridge,id=id[,br=bridge][,helper=helper]`` 3059 Connect a host TAP network interface to a host bridge device. 3060 3061 Use the network helper helper to configure the TAP interface and 3062 attach it to the bridge. The default network helper executable is 3063 ``/path/to/qemu-bridge-helper`` and the default bridge device is 3064 ``br0``. 3065 3066 Examples: 3067 3068 .. parsed-literal:: 3069 3070 #launch a QEMU instance with the default network helper to 3071 #connect a TAP device to bridge br0 3072 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1 3073 3074 .. parsed-literal:: 3075 3076 #launch a QEMU instance with the default network helper to 3077 #connect a TAP device to bridge qemubr0 3078 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1 3079 3080``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]`` 3081 This host network backend can be used to connect the guest's network 3082 to another QEMU virtual machine using a TCP socket connection. If 3083 ``listen`` is specified, QEMU waits for incoming connections on port 3084 (host is optional). ``connect`` is used to connect to another QEMU 3085 instance using the ``listen`` option. ``fd``\ =h specifies an 3086 already opened TCP socket. 3087 3088 Example: 3089 3090 .. parsed-literal:: 3091 3092 # launch a first QEMU instance 3093 |qemu_system| linux.img \\ 3094 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3095 -netdev socket,id=n1,listen=:1234 3096 # connect the network of this instance to the network of the first instance 3097 |qemu_system| linux.img \\ 3098 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3099 -netdev socket,id=n2,connect=127.0.0.1:1234 3100 3101``-netdev socket,id=id[,fd=h][,mcast=maddr:port[,localaddr=addr]]`` 3102 Configure a socket host network backend to share the guest's network 3103 traffic with another QEMU virtual machines using a UDP multicast 3104 socket, effectively making a bus for every QEMU with same multicast 3105 address maddr and port. NOTES: 3106 3107 1. Several QEMU can be running on different hosts and share same bus 3108 (assuming correct multicast setup for these hosts). 3109 3110 2. mcast support is compatible with User Mode Linux (argument 3111 ``ethN=mcast``), see http://user-mode-linux.sf.net. 3112 3113 3. Use ``fd=h`` to specify an already opened UDP multicast socket. 3114 3115 Example: 3116 3117 .. parsed-literal:: 3118 3119 # launch one QEMU instance 3120 |qemu_system| linux.img \\ 3121 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3122 -netdev socket,id=n1,mcast=230.0.0.1:1234 3123 # launch another QEMU instance on same "bus" 3124 |qemu_system| linux.img \\ 3125 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\ 3126 -netdev socket,id=n2,mcast=230.0.0.1:1234 3127 # launch yet another QEMU instance on same "bus" 3128 |qemu_system| linux.img \\ 3129 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\ 3130 -netdev socket,id=n3,mcast=230.0.0.1:1234 3131 3132 Example (User Mode Linux compat.): 3133 3134 .. parsed-literal:: 3135 3136 # launch QEMU instance (note mcast address selected is UML's default) 3137 |qemu_system| linux.img \\ 3138 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3139 -netdev socket,id=n1,mcast=239.192.168.1:1102 3140 # launch UML 3141 /path/to/linux ubd0=/path/to/root_fs eth0=mcast 3142 3143 Example (send packets from host's 1.2.3.4): 3144 3145 .. parsed-literal:: 3146 3147 |qemu_system| linux.img \\ 3148 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\ 3149 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4 3150 3151``-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]`` 3152 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931) 3153 is a popular protocol to transport Ethernet (and other Layer 2) data 3154 frames between two systems. It is present in routers, firewalls and 3155 the Linux kernel (from version 3.3 onwards). 3156 3157 This transport allows a VM to communicate to another VM, router or 3158 firewall directly. 3159 3160 ``src=srcaddr`` 3161 source address (mandatory) 3162 3163 ``dst=dstaddr`` 3164 destination address (mandatory) 3165 3166 ``udp`` 3167 select udp encapsulation (default is ip). 3168 3169 ``srcport=srcport`` 3170 source udp port. 3171 3172 ``dstport=dstport`` 3173 destination udp port. 3174 3175 ``ipv6`` 3176 force v6, otherwise defaults to v4. 3177 3178 ``rxcookie=rxcookie``; \ ``txcookie=txcookie`` 3179 Cookies are a weak form of security in the l2tpv3 specification. 3180 Their function is mostly to prevent misconfiguration. By default 3181 they are 32 bit. 3182 3183 ``cookie64`` 3184 Set cookie size to 64 bit instead of the default 32 3185 3186 ``counter=off`` 3187 Force a 'cut-down' L2TPv3 with no counter as in 3188 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00 3189 3190 ``pincounter=on`` 3191 Work around broken counter handling in peer. This may also help 3192 on networks which have packet reorder. 3193 3194 ``offset=offset`` 3195 Add an extra offset between header and data 3196 3197 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to 3198 the bridge br-lan on the remote Linux host 1.2.3.4: 3199 3200 .. parsed-literal:: 3201 3202 # Setup tunnel on linux host using raw ip as encapsulation 3203 # on 1.2.3.4 3204 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\ 3205 encap udp udp_sport 16384 udp_dport 16384 3206 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\ 3207 0xFFFFFFFF peer_session_id 0xFFFFFFFF 3208 ifconfig vmtunnel0 mtu 1500 3209 ifconfig vmtunnel0 up 3210 brctl addif br-lan vmtunnel0 3211 3212 3213 # on 4.3.2.1 3214 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter 3215 3216 |qemu_system| linux.img -device e1000,netdev=n1 \\ 3217 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter 3218 3219``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]`` 3220 Configure VDE backend to connect to PORT n of a vde switch running 3221 on host and listening for incoming connections on socketpath. Use 3222 GROUP groupname and MODE octalmode to change default ownership and 3223 permissions for communication port. This option is only available if 3224 QEMU has been compiled with vde support enabled. 3225 3226 Example: 3227 3228 .. parsed-literal:: 3229 3230 # launch vde switch 3231 vde_switch -F -sock /tmp/myswitch 3232 # launch QEMU instance 3233 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch 3234 3235``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]`` 3236 Establish a vhost-user netdev, backed by a chardev id. The chardev 3237 should be a unix domain socket backed one. The vhost-user uses a 3238 specifically defined protocol to pass vhost ioctl replacement 3239 messages to an application on the other end of the socket. On 3240 non-MSIX guests, the feature can be forced with vhostforce. Use 3241 'queues=n' to specify the number of queues to be created for 3242 multiqueue vhost-user. 3243 3244 Example: 3245 3246 :: 3247 3248 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \ 3249 -numa node,memdev=mem \ 3250 -chardev socket,id=chr0,path=/path/to/socket \ 3251 -netdev type=vhost-user,id=net0,chardev=chr0 \ 3252 -device virtio-net-pci,netdev=net0 3253 3254``-netdev vhost-vdpa,vhostdev=/path/to/dev`` 3255 Establish a vhost-vdpa netdev. 3256 3257 vDPA device is a device that uses a datapath which complies with 3258 the virtio specifications with a vendor specific control path. 3259 vDPA devices can be both physically located on the hardware or 3260 emulated by software. 3261 3262``-netdev hubport,id=id,hubid=hubid[,netdev=nd]`` 3263 Create a hub port on the emulated hub with ID hubid. 3264 3265 The hubport netdev lets you connect a NIC to a QEMU emulated hub 3266 instead of a single netdev. Alternatively, you can also connect the 3267 hubport to another netdev with ID nd by using the ``netdev=nd`` 3268 option. 3269 3270``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]`` 3271 Legacy option to configure or create an on-board (or machine 3272 default) Network Interface Card(NIC) and connect it either to the 3273 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd. 3274 If model is omitted, then the default NIC model associated with the 3275 machine type is used. Note that the default NIC model may change in 3276 future QEMU releases, so it is highly recommended to always specify 3277 a model. Optionally, the MAC address can be changed to mac, the 3278 device address set to addr (PCI cards only), and a name can be 3279 assigned for use in monitor commands. Optionally, for PCI cards, you 3280 can specify the number v of MSI-X vectors that the card should have; 3281 this option currently only affects virtio cards; set v = 0 to 3282 disable MSI-X. If no ``-net`` option is specified, a single NIC is 3283 created. QEMU can emulate several different models of network card. 3284 Use ``-net nic,model=help`` for a list of available devices for your 3285 target. 3286 3287``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]`` 3288 Configure a host network backend (with the options corresponding to 3289 the same ``-netdev`` option) and connect it to the emulated hub 0 3290 (the default hub). Use name to specify the name of the hub port. 3291ERST 3292 3293DEFHEADING() 3294 3295DEFHEADING(Character device options:) 3296 3297DEF("chardev", HAS_ARG, QEMU_OPTION_chardev, 3298 "-chardev help\n" 3299 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3300 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]\n" 3301 " [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n" 3302 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n" 3303 "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n" 3304 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n" 3305 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n" 3306 " [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n" 3307 " [,logfile=PATH][,logappend=on|off]\n" 3308 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3309 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n" 3310 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3311 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n" 3312 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3313 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3314#ifdef _WIN32 3315 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3316 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3317#else 3318 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3319 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n" 3320#endif 3321#ifdef CONFIG_BRLAPI 3322 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3323#endif 3324#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ 3325 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) 3326 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3327 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3328#endif 3329#if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__) 3330 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3331 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n" 3332#endif 3333#if defined(CONFIG_SPICE) 3334 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3335 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n" 3336#endif 3337 , QEMU_ARCH_ALL 3338) 3339 3340SRST 3341The general form of a character device option is: 3342 3343``-chardev backend,id=id[,mux=on|off][,options]`` 3344 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``, 3345 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``, 3346 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``, 3347 ``spicevmc``, ``spiceport``. The specific backend will determine the 3348 applicable options. 3349 3350 Use ``-chardev help`` to print all available chardev backend types. 3351 3352 All devices must have an id, which can be any string up to 127 3353 characters long. It is used to uniquely identify this device in 3354 other command line directives. 3355 3356 A character device may be used in multiplexing mode by multiple 3357 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is 3358 a "1:N" device, and here the "1" end is your specified chardev 3359 backend, and the "N" end is the various parts of QEMU that can talk 3360 to a chardev. If you create a chardev with ``id=myid`` and 3361 ``mux=on``, QEMU will create a multiplexer with your specified ID, 3362 and you can then configure multiple front ends to use that chardev 3363 ID for their input/output. Up to four different front ends can be 3364 connected to a single multiplexed chardev. (Without multiplexing 3365 enabled, a chardev can only be used by a single front end.) For 3366 instance you could use this to allow a single stdio chardev to be 3367 used by two serial ports and the QEMU monitor: 3368 3369 :: 3370 3371 -chardev stdio,mux=on,id=char0 \ 3372 -mon chardev=char0,mode=readline \ 3373 -serial chardev:char0 \ 3374 -serial chardev:char0 3375 3376 You can have more than one multiplexer in a system configuration; 3377 for instance you could have a TCP port multiplexed between UART 0 3378 and UART 1, and stdio multiplexed between the QEMU monitor and a 3379 parallel port: 3380 3381 :: 3382 3383 -chardev stdio,mux=on,id=char0 \ 3384 -mon chardev=char0,mode=readline \ 3385 -parallel chardev:char0 \ 3386 -chardev tcp,...,mux=on,id=char1 \ 3387 -serial chardev:char1 \ 3388 -serial chardev:char1 3389 3390 When you're using a multiplexed character device, some escape 3391 sequences are interpreted in the input. See the chapter about 3392 :ref:`keys in the character backend multiplexer` in the 3393 System Emulation Users Guide for more details. 3394 3395 Note that some other command line options may implicitly create 3396 multiplexed character backends; for instance ``-serial mon:stdio`` 3397 creates a multiplexed stdio backend connected to the serial port and 3398 the QEMU monitor, and ``-nographic`` also multiplexes the console 3399 and the monitor to stdio. 3400 3401 There is currently no support for multiplexing in the other 3402 direction (where a single QEMU front end takes input and output from 3403 multiple chardevs). 3404 3405 Every backend supports the ``logfile`` option, which supplies the 3406 path to a file to record all data transmitted via the backend. The 3407 ``logappend`` option controls whether the log file will be truncated 3408 or appended to when opened. 3409 3410The available backends are: 3411 3412``-chardev null,id=id`` 3413 A void device. This device will not emit any data, and will drop any 3414 data it receives. The null backend does not take any options. 3415 3416``-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]`` 3417 Create a two-way stream socket, which can be either a TCP or a unix 3418 socket. A unix socket will be created if ``path`` is specified. 3419 Behaviour is undefined if TCP options are specified for a unix 3420 socket. 3421 3422 ``server=on|off`` specifies that the socket shall be a listening socket. 3423 3424 ``wait=on|off`` specifies that QEMU should not block waiting for a client 3425 to connect to a listening socket. 3426 3427 ``telnet=on|off`` specifies that traffic on the socket should interpret 3428 telnet escape sequences. 3429 3430 ``websocket=on|off`` specifies that the socket uses WebSocket protocol for 3431 communication. 3432 3433 ``reconnect`` sets the timeout for reconnecting on non-server 3434 sockets when the remote end goes away. qemu will delay this many 3435 seconds and then attempt to reconnect. Zero disables reconnecting, 3436 and is the default. 3437 3438 ``tls-creds`` requests enablement of the TLS protocol for 3439 encryption, and specifies the id of the TLS credentials to use for 3440 the handshake. The credentials must be previously created with the 3441 ``-object tls-creds`` argument. 3442 3443 ``tls-auth`` provides the ID of the QAuthZ authorization object 3444 against which the client's x509 distinguished name will be 3445 validated. This object is only resolved at time of use, so can be 3446 deleted and recreated on the fly while the chardev server is active. 3447 If missing, it will default to denying access. 3448 3449 TCP and unix socket options are given below: 3450 3451 ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]`` 3452 ``host`` for a listening socket specifies the local address to 3453 be bound. For a connecting socket species the remote host to 3454 connect to. ``host`` is optional for listening sockets. If not 3455 specified it defaults to ``0.0.0.0``. 3456 3457 ``port`` for a listening socket specifies the local port to be 3458 bound. For a connecting socket specifies the port on the remote 3459 host to connect to. ``port`` can be given as either a port 3460 number or a service name. ``port`` is required. 3461 3462 ``to`` is only relevant to listening sockets. If it is 3463 specified, and ``port`` cannot be bound, QEMU will attempt to 3464 bind to subsequent ports up to and including ``to`` until it 3465 succeeds. ``to`` must be specified as a port number. 3466 3467 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 3468 or IPv6 must be used. If neither is specified the socket may 3469 use either protocol. 3470 3471 ``nodelay=on|off`` disables the Nagle algorithm. 3472 3473 ``unix options: path=path[,abstract=on|off][,tight=on|off]`` 3474 ``path`` specifies the local path of the unix socket. ``path`` 3475 is required. 3476 ``abstract=on|off`` specifies the use of the abstract socket namespace, 3477 rather than the filesystem. Optional, defaults to false. 3478 ``tight=on|off`` sets the socket length of abstract sockets to their minimum, 3479 rather than the full sun_path length. Optional, defaults to true. 3480 3481``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]`` 3482 Sends all traffic from the guest to a remote host over UDP. 3483 3484 ``host`` specifies the remote host to connect to. If not specified 3485 it defaults to ``localhost``. 3486 3487 ``port`` specifies the port on the remote host to connect to. 3488 ``port`` is required. 3489 3490 ``localaddr`` specifies the local address to bind to. If not 3491 specified it defaults to ``0.0.0.0``. 3492 3493 ``localport`` specifies the local port to bind to. If not specified 3494 any available local port will be used. 3495 3496 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used. 3497 If neither is specified the device may use either protocol. 3498 3499``-chardev msmouse,id=id`` 3500 Forward QEMU's emulated msmouse events to the guest. ``msmouse`` 3501 does not take any options. 3502 3503``-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]`` 3504 Connect to a QEMU text console. ``vc`` may optionally be given a 3505 specific size. 3506 3507 ``width`` and ``height`` specify the width and height respectively 3508 of the console, in pixels. 3509 3510 ``cols`` and ``rows`` specify that the console be sized to fit a 3511 text console with the given dimensions. 3512 3513``-chardev ringbuf,id=id[,size=size]`` 3514 Create a ring buffer with fixed size ``size``. size must be a power 3515 of two and defaults to ``64K``. 3516 3517``-chardev file,id=id,path=path`` 3518 Log all traffic received from the guest to a file. 3519 3520 ``path`` specifies the path of the file to be opened. This file will 3521 be created if it does not already exist, and overwritten if it does. 3522 ``path`` is required. 3523 3524``-chardev pipe,id=id,path=path`` 3525 Create a two-way connection to the guest. The behaviour differs 3526 slightly between Windows hosts and other hosts: 3527 3528 On Windows, a single duplex pipe will be created at 3529 ``\\.pipe\path``. 3530 3531 On other hosts, 2 pipes will be created called ``path.in`` and 3532 ``path.out``. Data written to ``path.in`` will be received by the 3533 guest. Data written by the guest can be read from ``path.out``. QEMU 3534 will not create these fifos, and requires them to be present. 3535 3536 ``path`` forms part of the pipe path as described above. ``path`` is 3537 required. 3538 3539``-chardev console,id=id`` 3540 Send traffic from the guest to QEMU's standard output. ``console`` 3541 does not take any options. 3542 3543 ``console`` is only available on Windows hosts. 3544 3545``-chardev serial,id=id,path=path`` 3546 Send traffic from the guest to a serial device on the host. 3547 3548 On Unix hosts serial will actually accept any tty device, not only 3549 serial lines. 3550 3551 ``path`` specifies the name of the serial device to open. 3552 3553``-chardev pty,id=id`` 3554 Create a new pseudo-terminal on the host and connect to it. ``pty`` 3555 does not take any options. 3556 3557 ``pty`` is not available on Windows hosts. 3558 3559``-chardev stdio,id=id[,signal=on|off]`` 3560 Connect to standard input and standard output of the QEMU process. 3561 3562 ``signal`` controls if signals are enabled on the terminal, that 3563 includes exiting QEMU with the key sequence Control-c. This option 3564 is enabled by default, use ``signal=off`` to disable it. 3565 3566``-chardev braille,id=id`` 3567 Connect to a local BrlAPI server. ``braille`` does not take any 3568 options. 3569 3570``-chardev tty,id=id,path=path`` 3571 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD 3572 and DragonFlyBSD hosts. It is an alias for ``serial``. 3573 3574 ``path`` specifies the path to the tty. ``path`` is required. 3575 3576``-chardev parallel,id=id,path=path`` 3577 \ 3578``-chardev parport,id=id,path=path`` 3579 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD 3580 hosts. 3581 3582 Connect to a local parallel port. 3583 3584 ``path`` specifies the path to the parallel port device. ``path`` is 3585 required. 3586 3587``-chardev spicevmc,id=id,debug=debug,name=name`` 3588 ``spicevmc`` is only available when spice support is built in. 3589 3590 ``debug`` debug level for spicevmc 3591 3592 ``name`` name of spice channel to connect to 3593 3594 Connect to a spice virtual machine channel, such as vdiport. 3595 3596``-chardev spiceport,id=id,debug=debug,name=name`` 3597 ``spiceport`` is only available when spice support is built in. 3598 3599 ``debug`` debug level for spicevmc 3600 3601 ``name`` name of spice port to connect to 3602 3603 Connect to a spice port, allowing a Spice client to handle the 3604 traffic identified by a name (preferably a fqdn). 3605ERST 3606 3607DEFHEADING() 3608 3609#ifdef CONFIG_TPM 3610DEFHEADING(TPM device options:) 3611 3612DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \ 3613 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n" 3614 " use path to provide path to a character device; default is /dev/tpm0\n" 3615 " use cancel-path to provide path to TPM's cancel sysfs entry; if\n" 3616 " not provided it will be searched for in /sys/class/misc/tpm?/device\n" 3617 "-tpmdev emulator,id=id,chardev=dev\n" 3618 " configure the TPM device using chardev backend\n", 3619 QEMU_ARCH_ALL) 3620SRST 3621The general form of a TPM device option is: 3622 3623``-tpmdev backend,id=id[,options]`` 3624 The specific backend type will determine the applicable options. The 3625 ``-tpmdev`` option creates the TPM backend and requires a 3626 ``-device`` option that specifies the TPM frontend interface model. 3627 3628 Use ``-tpmdev help`` to print all available TPM backend types. 3629 3630The available backends are: 3631 3632``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path`` 3633 (Linux-host only) Enable access to the host's TPM using the 3634 passthrough driver. 3635 3636 ``path`` specifies the path to the host's TPM device, i.e., on a 3637 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by 3638 default ``/dev/tpm0`` is used. 3639 3640 ``cancel-path`` specifies the path to the host TPM device's sysfs 3641 entry allowing for cancellation of an ongoing TPM command. 3642 ``cancel-path`` is optional and by default QEMU will search for the 3643 sysfs entry to use. 3644 3645 Some notes about using the host's TPM with the passthrough driver: 3646 3647 The TPM device accessed by the passthrough driver must not be used 3648 by any other application on the host. 3649 3650 Since the host's firmware (BIOS/UEFI) has already initialized the 3651 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize 3652 the TPM again and may therefore not show a TPM-specific menu that 3653 would otherwise allow the user to configure the TPM, e.g., allow the 3654 user to enable/disable or activate/deactivate the TPM. Further, if 3655 TPM ownership is released from within a VM then the host's TPM will 3656 get disabled and deactivated. To enable and activate the TPM again 3657 afterwards, the host has to be rebooted and the user is required to 3658 enter the firmware's menu to enable and activate the TPM. If the TPM 3659 is left disabled and/or deactivated most TPM commands will fail. 3660 3661 To create a passthrough TPM use the following two options: 3662 3663 :: 3664 3665 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0 3666 3667 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by 3668 ``tpmdev=tpm0`` in the device option. 3669 3670``-tpmdev emulator,id=id,chardev=dev`` 3671 (Linux-host only) Enable access to a TPM emulator using Unix domain 3672 socket based chardev backend. 3673 3674 ``chardev`` specifies the unique ID of a character device backend 3675 that provides connection to the software TPM server. 3676 3677 To create a TPM emulator backend device with chardev socket backend: 3678 3679 :: 3680 3681 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0 3682ERST 3683 3684DEFHEADING() 3685 3686#endif 3687 3688DEFHEADING(Linux/Multiboot boot specific:) 3689SRST 3690When using these options, you can use a given Linux or Multiboot kernel 3691without installing it in the disk image. It can be useful for easier 3692testing of various kernels. 3693 3694 3695ERST 3696 3697DEF("kernel", HAS_ARG, QEMU_OPTION_kernel, \ 3698 "-kernel bzImage use 'bzImage' as kernel image\n", QEMU_ARCH_ALL) 3699SRST 3700``-kernel bzImage`` 3701 Use bzImage as kernel image. The kernel can be either a Linux kernel 3702 or in multiboot format. 3703ERST 3704 3705DEF("append", HAS_ARG, QEMU_OPTION_append, \ 3706 "-append cmdline use 'cmdline' as kernel command line\n", QEMU_ARCH_ALL) 3707SRST 3708``-append cmdline`` 3709 Use cmdline as kernel command line 3710ERST 3711 3712DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \ 3713 "-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL) 3714SRST 3715``-initrd file`` 3716 Use file as initial ram disk. 3717 3718``-initrd "file1 arg=foo,file2"`` 3719 This syntax is only available with multiboot. 3720 3721 Use file1 and file2 as modules and pass arg=foo as parameter to the 3722 first module. 3723ERST 3724 3725DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \ 3726 "-dtb file use 'file' as device tree image\n", QEMU_ARCH_ALL) 3727SRST 3728``-dtb file`` 3729 Use file as a device tree binary (dtb) image and pass it to the 3730 kernel on boot. 3731ERST 3732 3733DEFHEADING() 3734 3735DEFHEADING(Debug/Expert options:) 3736 3737DEF("compat", HAS_ARG, QEMU_OPTION_compat, 3738 "-compat [deprecated-input=accept|reject|crash][,deprecated-output=accept|hide]\n" 3739 " Policy for handling deprecated management interfaces\n" 3740 "-compat [unstable-input=accept|reject|crash][,unstable-output=accept|hide]\n" 3741 " Policy for handling unstable management interfaces\n", 3742 QEMU_ARCH_ALL) 3743SRST 3744``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]`` 3745 Set policy for handling deprecated management interfaces (experimental): 3746 3747 ``deprecated-input=accept`` (default) 3748 Accept deprecated commands and arguments 3749 ``deprecated-input=reject`` 3750 Reject deprecated commands and arguments 3751 ``deprecated-input=crash`` 3752 Crash on deprecated commands and arguments 3753 ``deprecated-output=accept`` (default) 3754 Emit deprecated command results and events 3755 ``deprecated-output=hide`` 3756 Suppress deprecated command results and events 3757 3758 Limitation: covers only syntactic aspects of QMP. 3759 3760``-compat [unstable-input=@var{input-policy}][,unstable-output=@var{output-policy}]`` 3761 Set policy for handling unstable management interfaces (experimental): 3762 3763 ``unstable-input=accept`` (default) 3764 Accept unstable commands and arguments 3765 ``unstable-input=reject`` 3766 Reject unstable commands and arguments 3767 ``unstable-input=crash`` 3768 Crash on unstable commands and arguments 3769 ``unstable-output=accept`` (default) 3770 Emit unstable command results and events 3771 ``unstable-output=hide`` 3772 Suppress unstable command results and events 3773 3774 Limitation: covers only syntactic aspects of QMP. 3775ERST 3776 3777DEF("fw_cfg", HAS_ARG, QEMU_OPTION_fwcfg, 3778 "-fw_cfg [name=]<name>,file=<file>\n" 3779 " add named fw_cfg entry with contents from file\n" 3780 "-fw_cfg [name=]<name>,string=<str>\n" 3781 " add named fw_cfg entry with contents from string\n", 3782 QEMU_ARCH_ALL) 3783SRST 3784``-fw_cfg [name=]name,file=file`` 3785 Add named fw\_cfg entry with contents from file file. 3786 3787``-fw_cfg [name=]name,string=str`` 3788 Add named fw\_cfg entry with contents from string str. 3789 3790 The terminating NUL character of the contents of str will not be 3791 included as part of the fw\_cfg item data. To insert contents with 3792 embedded NUL characters, you have to use the file parameter. 3793 3794 The fw\_cfg entries are passed by QEMU through to the guest. 3795 3796 Example: 3797 3798 :: 3799 3800 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin 3801 3802 creates an fw\_cfg entry named opt/com.mycompany/blob with contents 3803 from ./my\_blob.bin. 3804ERST 3805 3806DEF("serial", HAS_ARG, QEMU_OPTION_serial, \ 3807 "-serial dev redirect the serial port to char device 'dev'\n", 3808 QEMU_ARCH_ALL) 3809SRST 3810``-serial dev`` 3811 Redirect the virtual serial port to host character device dev. The 3812 default device is ``vc`` in graphical mode and ``stdio`` in non 3813 graphical mode. 3814 3815 This option can be used several times to simulate up to 4 serial 3816 ports. 3817 3818 Use ``-serial none`` to disable all serial ports. 3819 3820 Available character devices are: 3821 3822 ``vc[:WxH]`` 3823 Virtual console. Optionally, a width and height can be given in 3824 pixel with 3825 3826 :: 3827 3828 vc:800x600 3829 3830 It is also possible to specify width or height in characters: 3831 3832 :: 3833 3834 vc:80Cx24C 3835 3836 ``pty`` 3837 [Linux only] Pseudo TTY (a new PTY is automatically allocated) 3838 3839 ``none`` 3840 No device is allocated. 3841 3842 ``null`` 3843 void device 3844 3845 ``chardev:id`` 3846 Use a named character device defined with the ``-chardev`` 3847 option. 3848 3849 ``/dev/XXX`` 3850 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial 3851 port parameters are set according to the emulated ones. 3852 3853 ``/dev/parportN`` 3854 [Linux only, parallel port only] Use host parallel port N. 3855 Currently SPP and EPP parallel port features can be used. 3856 3857 ``file:filename`` 3858 Write output to filename. No character can be read. 3859 3860 ``stdio`` 3861 [Unix only] standard input/output 3862 3863 ``pipe:filename`` 3864 name pipe filename 3865 3866 ``COMn`` 3867 [Windows only] Use host serial port n 3868 3869 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]`` 3870 This implements UDP Net Console. When remote\_host or src\_ip 3871 are not specified they default to ``0.0.0.0``. When not using a 3872 specified src\_port a random port is automatically chosen. 3873 3874 If you just want a simple readonly console you can use 3875 ``netcat`` or ``nc``, by starting QEMU with: 3876 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time 3877 QEMU writes something to that port it will appear in the 3878 netconsole session. 3879 3880 If you plan to send characters back via netconsole or you want 3881 to stop and start QEMU a lot of times, you should have QEMU use 3882 the same source port each time by using something like ``-serial 3883 udp::4555@:4556`` to QEMU. Another approach is to use a patched 3884 version of netcat which can listen to a TCP port and send and 3885 receive characters via udp. If you have a patched version of 3886 netcat which activates telnet remote echo and single char 3887 transfer, then you can use the following options to set up a 3888 netcat redirector to allow telnet on port 5555 to access the 3889 QEMU port. 3890 3891 ``QEMU Options:`` 3892 -serial udp::4555@:4556 3893 3894 ``netcat options:`` 3895 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T 3896 3897 ``telnet options:`` 3898 localhost 5555 3899 3900 ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]`` 3901 The TCP Net Console has two modes of operation. It can send the 3902 serial I/O to a location or wait for a connection from a 3903 location. By default the TCP Net Console is sent to host at the 3904 port. If you use the ``server=on`` option QEMU will wait for a client 3905 socket application to connect to the port before continuing, 3906 unless the ``wait=on|off`` option was specified. The ``nodelay=on|off`` 3907 option disables the Nagle buffering algorithm. The ``reconnect=on`` 3908 option only applies if ``server=no`` is set, if the connection goes 3909 down it will attempt to reconnect at the given interval. If host 3910 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a 3911 time is accepted. You can use ``telnet=on`` to connect to the 3912 corresponding character device. 3913 3914 ``Example to send tcp console to 192.168.0.2 port 4444`` 3915 -serial tcp:192.168.0.2:4444 3916 3917 ``Example to listen and wait on port 4444 for connection`` 3918 -serial tcp::4444,server=on 3919 3920 ``Example to not wait and listen on ip 192.168.0.100 port 4444`` 3921 -serial tcp:192.168.0.100:4444,server=on,wait=off 3922 3923 ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]`` 3924 The telnet protocol is used instead of raw tcp sockets. The 3925 options work the same as if you had specified ``-serial tcp``. 3926 The difference is that the port acts like a telnet server or 3927 client using telnet option negotiation. This will also allow you 3928 to send the MAGIC\_SYSRQ sequence if you use a telnet that 3929 supports sending the break sequence. Typically in unix telnet 3930 you do it with Control-] and then type "send break" followed by 3931 pressing the enter key. 3932 3933 ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]`` 3934 The WebSocket protocol is used instead of raw tcp socket. The 3935 port acts as a WebSocket server. Client mode is not supported. 3936 3937 ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]`` 3938 A unix domain socket is used instead of a tcp socket. The option 3939 works the same as if you had specified ``-serial tcp`` except 3940 the unix domain socket path is used for connections. 3941 3942 ``mon:dev_string`` 3943 This is a special option to allow the monitor to be multiplexed 3944 onto another serial port. The monitor is accessed with key 3945 sequence of Control-a and then pressing c. dev\_string should be 3946 any one of the serial devices specified above. An example to 3947 multiplex the monitor onto a telnet server listening on port 3948 4444 would be: 3949 3950 ``-serial mon:telnet::4444,server=on,wait=off`` 3951 3952 When the monitor is multiplexed to stdio in this way, Ctrl+C 3953 will not terminate QEMU any more but will be passed to the guest 3954 instead. 3955 3956 ``braille`` 3957 Braille device. This will use BrlAPI to display the braille 3958 output on a real or fake device. 3959 3960 ``msmouse`` 3961 Three button serial mouse. Configure the guest to use Microsoft 3962 protocol. 3963ERST 3964 3965DEF("parallel", HAS_ARG, QEMU_OPTION_parallel, \ 3966 "-parallel dev redirect the parallel port to char device 'dev'\n", 3967 QEMU_ARCH_ALL) 3968SRST 3969``-parallel dev`` 3970 Redirect the virtual parallel port to host device dev (same devices 3971 as the serial port). On Linux hosts, ``/dev/parportN`` can be used 3972 to use hardware devices connected on the corresponding host parallel 3973 port. 3974 3975 This option can be used several times to simulate up to 3 parallel 3976 ports. 3977 3978 Use ``-parallel none`` to disable all parallel ports. 3979ERST 3980 3981DEF("monitor", HAS_ARG, QEMU_OPTION_monitor, \ 3982 "-monitor dev redirect the monitor to char device 'dev'\n", 3983 QEMU_ARCH_ALL) 3984SRST 3985``-monitor dev`` 3986 Redirect the monitor to host device dev (same devices as the serial 3987 port). The default device is ``vc`` in graphical mode and ``stdio`` 3988 in non graphical mode. Use ``-monitor none`` to disable the default 3989 monitor. 3990ERST 3991DEF("qmp", HAS_ARG, QEMU_OPTION_qmp, \ 3992 "-qmp dev like -monitor but opens in 'control' mode\n", 3993 QEMU_ARCH_ALL) 3994SRST 3995``-qmp dev`` 3996 Like -monitor but opens in 'control' mode. 3997ERST 3998DEF("qmp-pretty", HAS_ARG, QEMU_OPTION_qmp_pretty, \ 3999 "-qmp-pretty dev like -qmp but uses pretty JSON formatting\n", 4000 QEMU_ARCH_ALL) 4001SRST 4002``-qmp-pretty dev`` 4003 Like -qmp but uses pretty JSON formatting. 4004ERST 4005 4006DEF("mon", HAS_ARG, QEMU_OPTION_mon, \ 4007 "-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]\n", QEMU_ARCH_ALL) 4008SRST 4009``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]`` 4010 Setup monitor on chardev name. ``mode=control`` configures 4011 a QMP monitor (a JSON RPC-style protocol) and it is not the 4012 same as HMP, the human monitor that has a "(qemu)" prompt. 4013 ``pretty`` is only valid when ``mode=control``, 4014 turning on JSON pretty printing to ease 4015 human reading and debugging. 4016ERST 4017 4018DEF("debugcon", HAS_ARG, QEMU_OPTION_debugcon, \ 4019 "-debugcon dev redirect the debug console to char device 'dev'\n", 4020 QEMU_ARCH_ALL) 4021SRST 4022``-debugcon dev`` 4023 Redirect the debug console to host device dev (same devices as the 4024 serial port). The debug console is an I/O port which is typically 4025 port 0xe9; writing to that I/O port sends output to this device. The 4026 default device is ``vc`` in graphical mode and ``stdio`` in non 4027 graphical mode. 4028ERST 4029 4030DEF("pidfile", HAS_ARG, QEMU_OPTION_pidfile, \ 4031 "-pidfile file write PID to 'file'\n", QEMU_ARCH_ALL) 4032SRST 4033``-pidfile file`` 4034 Store the QEMU process PID in file. It is useful if you launch QEMU 4035 from a script. 4036ERST 4037 4038DEF("singlestep", 0, QEMU_OPTION_singlestep, \ 4039 "-singlestep always run in singlestep mode\n", QEMU_ARCH_ALL) 4040SRST 4041``-singlestep`` 4042 Run the emulation in single step mode. 4043ERST 4044 4045DEF("preconfig", 0, QEMU_OPTION_preconfig, \ 4046 "--preconfig pause QEMU before machine is initialized (experimental)\n", 4047 QEMU_ARCH_ALL) 4048SRST 4049``--preconfig`` 4050 Pause QEMU for interactive configuration before the machine is 4051 created, which allows querying and configuring properties that will 4052 affect machine initialization. Use QMP command 'x-exit-preconfig' to 4053 exit the preconfig state and move to the next state (i.e. run guest 4054 if -S isn't used or pause the second time if -S is used). This 4055 option is experimental. 4056ERST 4057 4058DEF("S", 0, QEMU_OPTION_S, \ 4059 "-S freeze CPU at startup (use 'c' to start execution)\n", 4060 QEMU_ARCH_ALL) 4061SRST 4062``-S`` 4063 Do not start CPU at startup (you must type 'c' in the monitor). 4064ERST 4065 4066DEF("overcommit", HAS_ARG, QEMU_OPTION_overcommit, 4067 "-overcommit [mem-lock=on|off][cpu-pm=on|off]\n" 4068 " run qemu with overcommit hints\n" 4069 " mem-lock=on|off controls memory lock support (default: off)\n" 4070 " cpu-pm=on|off controls cpu power management (default: off)\n", 4071 QEMU_ARCH_ALL) 4072SRST 4073``-overcommit mem-lock=on|off`` 4074 \ 4075``-overcommit cpu-pm=on|off`` 4076 Run qemu with hints about host resource overcommit. The default is 4077 to assume that host overcommits all resources. 4078 4079 Locking qemu and guest memory can be enabled via ``mem-lock=on`` 4080 (disabled by default). This works when host memory is not 4081 overcommitted and reduces the worst-case latency for guest. 4082 4083 Guest ability to manage power state of host cpus (increasing latency 4084 for other processes on the same host cpu, but decreasing latency for 4085 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This 4086 works best when host CPU is not overcommitted. When used, host 4087 estimates of CPU cycle and power utilization will be incorrect, not 4088 taking into account guest idle time. 4089ERST 4090 4091DEF("gdb", HAS_ARG, QEMU_OPTION_gdb, \ 4092 "-gdb dev accept gdb connection on 'dev'. (QEMU defaults to starting\n" 4093 " the guest without waiting for gdb to connect; use -S too\n" 4094 " if you want it to not start execution.)\n", 4095 QEMU_ARCH_ALL) 4096SRST 4097``-gdb dev`` 4098 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter 4099 in the System Emulation Users Guide). Note that this option does not pause QEMU 4100 execution -- if you want QEMU to not start the guest until you 4101 connect with gdb and issue a ``continue`` command, you will need to 4102 also pass the ``-S`` option to QEMU. 4103 4104 The most usual configuration is to listen on a local TCP socket:: 4105 4106 -gdb tcp::3117 4107 4108 but you can specify other backends; UDP, pseudo TTY, or even stdio 4109 are all reasonable use cases. For example, a stdio connection 4110 allows you to start QEMU from within gdb and establish the 4111 connection via a pipe: 4112 4113 .. parsed-literal:: 4114 4115 (gdb) target remote | exec |qemu_system| -gdb stdio ... 4116ERST 4117 4118DEF("s", 0, QEMU_OPTION_s, \ 4119 "-s shorthand for -gdb tcp::" DEFAULT_GDBSTUB_PORT "\n", 4120 QEMU_ARCH_ALL) 4121SRST 4122``-s`` 4123 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234 4124 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide). 4125ERST 4126 4127DEF("d", HAS_ARG, QEMU_OPTION_d, \ 4128 "-d item1,... enable logging of specified items (use '-d help' for a list of log items)\n", 4129 QEMU_ARCH_ALL) 4130SRST 4131``-d item1[,...]`` 4132 Enable logging of specified items. Use '-d help' for a list of log 4133 items. 4134ERST 4135 4136DEF("D", HAS_ARG, QEMU_OPTION_D, \ 4137 "-D logfile output log to logfile (default stderr)\n", 4138 QEMU_ARCH_ALL) 4139SRST 4140``-D logfile`` 4141 Output log in logfile instead of to stderr 4142ERST 4143 4144DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \ 4145 "-dfilter range,.. filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n", 4146 QEMU_ARCH_ALL) 4147SRST 4148``-dfilter range1[,...]`` 4149 Filter debug output to that relevant to a range of target addresses. 4150 The filter spec can be either start+size, start-size or start..end 4151 where start end and size are the addresses and sizes required. For 4152 example: 4153 4154 :: 4155 4156 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000 4157 4158 Will dump output for any code in the 0x1000 sized block starting at 4159 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and 4160 another 0x1000 sized block starting at 0xffffffc00005f000. 4161ERST 4162 4163DEF("seed", HAS_ARG, QEMU_OPTION_seed, \ 4164 "-seed number seed the pseudo-random number generator\n", 4165 QEMU_ARCH_ALL) 4166SRST 4167``-seed number`` 4168 Force the guest to use a deterministic pseudo-random number 4169 generator, seeded with number. This does not affect crypto routines 4170 within the host. 4171ERST 4172 4173DEF("L", HAS_ARG, QEMU_OPTION_L, \ 4174 "-L path set the directory for the BIOS, VGA BIOS and keymaps\n", 4175 QEMU_ARCH_ALL) 4176SRST 4177``-L path`` 4178 Set the directory for the BIOS, VGA BIOS and keymaps. 4179 4180 To list all the data directories, use ``-L help``. 4181ERST 4182 4183DEF("bios", HAS_ARG, QEMU_OPTION_bios, \ 4184 "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL) 4185SRST 4186``-bios file`` 4187 Set the filename for the BIOS. 4188ERST 4189 4190DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \ 4191 "-enable-kvm enable KVM full virtualization support\n", 4192 QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC | 4193 QEMU_ARCH_RISCV | QEMU_ARCH_S390X) 4194SRST 4195``-enable-kvm`` 4196 Enable KVM full virtualization support. This option is only 4197 available if KVM support is enabled when compiling. 4198ERST 4199 4200DEF("xen-domid", HAS_ARG, QEMU_OPTION_xen_domid, 4201 "-xen-domid id specify xen guest domain id\n", 4202 QEMU_ARCH_ARM | QEMU_ARCH_I386) 4203DEF("xen-attach", 0, QEMU_OPTION_xen_attach, 4204 "-xen-attach attach to existing xen domain\n" 4205 " libxl will use this when starting QEMU\n", 4206 QEMU_ARCH_ARM | QEMU_ARCH_I386) 4207DEF("xen-domid-restrict", 0, QEMU_OPTION_xen_domid_restrict, 4208 "-xen-domid-restrict restrict set of available xen operations\n" 4209 " to specified domain id. (Does not affect\n" 4210 " xenpv machine type).\n", 4211 QEMU_ARCH_ARM | QEMU_ARCH_I386) 4212SRST 4213``-xen-domid id`` 4214 Specify xen guest domain id (XEN only). 4215 4216``-xen-attach`` 4217 Attach to existing xen domain. libxl will use this when starting 4218 QEMU (XEN only). Restrict set of available xen operations to 4219 specified domain id (XEN only). 4220ERST 4221 4222DEF("no-reboot", 0, QEMU_OPTION_no_reboot, \ 4223 "-no-reboot exit instead of rebooting\n", QEMU_ARCH_ALL) 4224SRST 4225``-no-reboot`` 4226 Exit instead of rebooting. 4227ERST 4228 4229DEF("no-shutdown", 0, QEMU_OPTION_no_shutdown, \ 4230 "-no-shutdown stop before shutdown\n", QEMU_ARCH_ALL) 4231SRST 4232``-no-shutdown`` 4233 Don't exit QEMU on guest shutdown, but instead only stop the 4234 emulation. This allows for instance switching to monitor to commit 4235 changes to the disk image. 4236ERST 4237 4238DEF("action", HAS_ARG, QEMU_OPTION_action, 4239 "-action reboot=reset|shutdown\n" 4240 " action when guest reboots [default=reset]\n" 4241 "-action shutdown=poweroff|pause\n" 4242 " action when guest shuts down [default=poweroff]\n" 4243 "-action panic=pause|shutdown|none\n" 4244 " action when guest panics [default=shutdown]\n" 4245 "-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" 4246 " action when watchdog fires [default=reset]\n", 4247 QEMU_ARCH_ALL) 4248SRST 4249``-action event=action`` 4250 The action parameter serves to modify QEMU's default behavior when 4251 certain guest events occur. It provides a generic method for specifying the 4252 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown`` 4253 parameters. 4254 4255 Examples: 4256 4257 ``-action panic=none`` 4258 ``-action reboot=shutdown,shutdown=pause`` 4259 ``-watchdog i6300esb -action watchdog=pause`` 4260 4261ERST 4262 4263DEF("loadvm", HAS_ARG, QEMU_OPTION_loadvm, \ 4264 "-loadvm [tag|id]\n" \ 4265 " start right away with a saved state (loadvm in monitor)\n", 4266 QEMU_ARCH_ALL) 4267SRST 4268``-loadvm file`` 4269 Start right away with a saved state (``loadvm`` in monitor) 4270ERST 4271 4272#ifndef _WIN32 4273DEF("daemonize", 0, QEMU_OPTION_daemonize, \ 4274 "-daemonize daemonize QEMU after initializing\n", QEMU_ARCH_ALL) 4275#endif 4276SRST 4277``-daemonize`` 4278 Daemonize the QEMU process after initialization. QEMU will not 4279 detach from standard IO until it is ready to receive connections on 4280 any of its devices. This option is a useful way for external 4281 programs to launch QEMU without having to cope with initialization 4282 race conditions. 4283ERST 4284 4285DEF("option-rom", HAS_ARG, QEMU_OPTION_option_rom, \ 4286 "-option-rom rom load a file, rom, into the option ROM space\n", 4287 QEMU_ARCH_ALL) 4288SRST 4289``-option-rom file`` 4290 Load the contents of file as an option ROM. This option is useful to 4291 load things like EtherBoot. 4292ERST 4293 4294DEF("rtc", HAS_ARG, QEMU_OPTION_rtc, \ 4295 "-rtc [base=utc|localtime|<datetime>][,clock=host|rt|vm][,driftfix=none|slew]\n" \ 4296 " set the RTC base and clock, enable drift fix for clock ticks (x86 only)\n", 4297 QEMU_ARCH_ALL) 4298 4299SRST 4300``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]`` 4301 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at 4302 the current UTC or local time, respectively. ``localtime`` is 4303 required for correct date in MS-DOS or Windows. To start at a 4304 specific point in time, provide datetime in the format 4305 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC. 4306 4307 By default the RTC is driven by the host system time. This allows 4308 using of the RTC as accurate reference clock inside the guest, 4309 specifically if the host time is smoothly following an accurate 4310 external reference clock, e.g. via NTP. If you want to isolate the 4311 guest time from the host, you can set ``clock`` to ``rt`` instead, 4312 which provides a host monotonic clock if host support it. To even 4313 prevent the RTC from progressing during suspension, you can set 4314 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is 4315 recommended especially in icount mode in order to preserve 4316 determinism; however, note that in icount mode the speed of the 4317 virtual clock is variable and can in general differ from the host 4318 clock. 4319 4320 Enable ``driftfix`` (i386 targets only) if you experience time drift 4321 problems, specifically with Windows' ACPI HAL. This option will try 4322 to figure out how many timer interrupts were not processed by the 4323 Windows guest and will re-inject them. 4324ERST 4325 4326DEF("icount", HAS_ARG, QEMU_OPTION_icount, \ 4327 "-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=<filename>[,rrsnapshot=<snapshot>]]\n" \ 4328 " enable virtual instruction counter with 2^N clock ticks per\n" \ 4329 " instruction, enable aligning the host and virtual clocks\n" \ 4330 " or disable real time cpu sleeping, and optionally enable\n" \ 4331 " record-and-replay mode\n", QEMU_ARCH_ALL) 4332SRST 4333``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]`` 4334 Enable virtual instruction counter. The virtual cpu will execute one 4335 instruction every 2^N ns of virtual time. If ``auto`` is specified 4336 then the virtual cpu speed will be automatically adjusted to keep 4337 virtual time within a few seconds of real time. 4338 4339 Note that while this option can give deterministic behavior, it does 4340 not provide cycle accurate emulation. Modern CPUs contain 4341 superscalar out of order cores with complex cache hierarchies. The 4342 number of instructions executed often has little or no correlation 4343 with actual performance. 4344 4345 When the virtual cpu is sleeping, the virtual time will advance at 4346 default speed unless ``sleep=on`` is specified. With 4347 ``sleep=on``, the virtual time will jump to the next timer 4348 deadline instantly whenever the virtual cpu goes to sleep mode and 4349 will not advance if no timer is enabled. This behavior gives 4350 deterministic execution times from the guest point of view. 4351 The default if icount is enabled is ``sleep=off``. 4352 ``sleep=on`` cannot be used together with either ``shift=auto`` 4353 or ``align=on``. 4354 4355 ``align=on`` will activate the delay algorithm which will try to 4356 synchronise the host clock and the virtual clock. The goal is to 4357 have a guest running at the real frequency imposed by the shift 4358 option. Whenever the guest clock is behind the host clock and if 4359 ``align=on`` is specified then we print a message to the user to 4360 inform about the delay. Currently this option does not work when 4361 ``shift`` is ``auto``. Note: The sync algorithm will work for those 4362 shift values for which the guest clock runs ahead of the host clock. 4363 Typically this happens when the shift value is high (how high 4364 depends on the host machine). The default if icount is enabled 4365 is ``align=off``. 4366 4367 When the ``rr`` option is specified deterministic record/replay is 4368 enabled. The ``rrfile=`` option must also be provided to 4369 specify the path to the replay log. In record mode data is written 4370 to this file, and in replay mode it is read back. 4371 If the ``rrsnapshot`` option is given then it specifies a VM snapshot 4372 name. In record mode, a new VM snapshot with the given name is created 4373 at the start of execution recording. In replay mode this option 4374 specifies the snapshot name used to load the initial VM state. 4375ERST 4376 4377DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \ 4378 "-watchdog model\n" \ 4379 " enable virtual hardware watchdog [default=none]\n", 4380 QEMU_ARCH_ALL) 4381SRST 4382``-watchdog model`` 4383 Create a virtual hardware watchdog device. Once enabled (by a guest 4384 action), the watchdog must be periodically polled by an agent inside 4385 the guest or else the guest will be restarted. Choose a model for 4386 which your guest has drivers. 4387 4388 The model is the model of hardware watchdog to emulate. Use 4389 ``-watchdog help`` to list available hardware models. Only one 4390 watchdog can be enabled for a guest. 4391 4392 The following models may be available: 4393 4394 ``ib700`` 4395 iBASE 700 is a very simple ISA watchdog with a single timer. 4396 4397 ``i6300esb`` 4398 Intel 6300ESB I/O controller hub is a much more featureful 4399 PCI-based dual-timer watchdog. 4400 4401 ``diag288`` 4402 A virtual watchdog for s390x backed by the diagnose 288 4403 hypercall (currently KVM only). 4404ERST 4405 4406DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \ 4407 "-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \ 4408 " action when watchdog fires [default=reset]\n", 4409 QEMU_ARCH_ALL) 4410SRST 4411``-watchdog-action action`` 4412 The action controls what QEMU will do when the watchdog timer 4413 expires. The default is ``reset`` (forcefully reset the guest). 4414 Other possible actions are: ``shutdown`` (attempt to gracefully 4415 shutdown the guest), ``poweroff`` (forcefully poweroff the guest), 4416 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the 4417 guest), ``debug`` (print a debug message and continue), or ``none`` 4418 (do nothing). 4419 4420 Note that the ``shutdown`` action requires that the guest responds 4421 to ACPI signals, which it may not be able to do in the sort of 4422 situations where the watchdog would have expired, and thus 4423 ``-watchdog-action shutdown`` is not recommended for production use. 4424 4425 Examples: 4426 4427 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700`` 4428 4429ERST 4430 4431DEF("echr", HAS_ARG, QEMU_OPTION_echr, \ 4432 "-echr chr set terminal escape character instead of ctrl-a\n", 4433 QEMU_ARCH_ALL) 4434SRST 4435``-echr numeric_ascii_value`` 4436 Change the escape character used for switching to the monitor when 4437 using monitor and serial sharing. The default is ``0x01`` when using 4438 the ``-nographic`` option. ``0x01`` is equal to pressing 4439 ``Control-a``. You can select a different character from the ascii 4440 control keys where 1 through 26 map to Control-a through Control-z. 4441 For instance you could use the either of the following to change the 4442 escape character to Control-t. 4443 4444 ``-echr 0x14``; \ ``-echr 20`` 4445 4446ERST 4447 4448DEF("incoming", HAS_ARG, QEMU_OPTION_incoming, \ 4449 "-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]\n" \ 4450 "-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]\n" \ 4451 "-incoming unix:socketpath\n" \ 4452 " prepare for incoming migration, listen on\n" \ 4453 " specified protocol and socket address\n" \ 4454 "-incoming fd:fd\n" \ 4455 "-incoming exec:cmdline\n" \ 4456 " accept incoming migration on given file descriptor\n" \ 4457 " or from given external command\n" \ 4458 "-incoming defer\n" \ 4459 " wait for the URI to be specified via migrate_incoming\n", 4460 QEMU_ARCH_ALL) 4461SRST 4462``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]`` 4463 \ 4464``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]`` 4465 Prepare for incoming migration, listen on a given tcp port. 4466 4467``-incoming unix:socketpath`` 4468 Prepare for incoming migration, listen on a given unix socket. 4469 4470``-incoming fd:fd`` 4471 Accept incoming migration from a given filedescriptor. 4472 4473``-incoming exec:cmdline`` 4474 Accept incoming migration as an output from specified external 4475 command. 4476 4477``-incoming defer`` 4478 Wait for the URI to be specified via migrate\_incoming. The monitor 4479 can be used to change settings (such as migration parameters) prior 4480 to issuing the migrate\_incoming to allow the migration to begin. 4481ERST 4482 4483DEF("only-migratable", 0, QEMU_OPTION_only_migratable, \ 4484 "-only-migratable allow only migratable devices\n", QEMU_ARCH_ALL) 4485SRST 4486``-only-migratable`` 4487 Only allow migratable devices. Devices will not be allowed to enter 4488 an unmigratable state. 4489ERST 4490 4491DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \ 4492 "-nodefaults don't create default devices\n", QEMU_ARCH_ALL) 4493SRST 4494``-nodefaults`` 4495 Don't create default devices. Normally, QEMU sets the default 4496 devices like serial port, parallel port, virtual console, monitor 4497 device, VGA adapter, floppy and CD-ROM drive and others. The 4498 ``-nodefaults`` option will disable all those default devices. 4499ERST 4500 4501#ifndef _WIN32 4502DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \ 4503 "-chroot dir chroot to dir just before starting the VM\n", 4504 QEMU_ARCH_ALL) 4505#endif 4506SRST 4507``-chroot dir`` 4508 Immediately before starting guest execution, chroot to the specified 4509 directory. Especially useful in combination with -runas. 4510ERST 4511 4512#ifndef _WIN32 4513DEF("runas", HAS_ARG, QEMU_OPTION_runas, \ 4514 "-runas user change to user id user just before starting the VM\n" \ 4515 " user can be numeric uid:gid instead\n", 4516 QEMU_ARCH_ALL) 4517#endif 4518SRST 4519``-runas user`` 4520 Immediately before starting guest execution, drop root privileges, 4521 switching to the specified user. 4522ERST 4523 4524DEF("prom-env", HAS_ARG, QEMU_OPTION_prom_env, 4525 "-prom-env variable=value\n" 4526 " set OpenBIOS nvram variables\n", 4527 QEMU_ARCH_PPC | QEMU_ARCH_SPARC) 4528SRST 4529``-prom-env variable=value`` 4530 Set OpenBIOS nvram variable to given value (PPC, SPARC only). 4531 4532 :: 4533 4534 qemu-system-sparc -prom-env 'auto-boot?=false' \ 4535 -prom-env 'boot-device=sd(0,2,0):d' -prom-env 'boot-args=linux single' 4536 4537 :: 4538 4539 qemu-system-ppc -prom-env 'auto-boot?=false' \ 4540 -prom-env 'boot-device=hd:2,\yaboot' \ 4541 -prom-env 'boot-args=conf=hd:2,\yaboot.conf' 4542ERST 4543DEF("semihosting", 0, QEMU_OPTION_semihosting, 4544 "-semihosting semihosting mode\n", 4545 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4546 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4547SRST 4548``-semihosting`` 4549 Enable semihosting mode (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V only). 4550 4551 Note that this allows guest direct access to the host filesystem, so 4552 should only be used with a trusted guest OS. 4553 4554 See the -semihosting-config option documentation for further 4555 information about the facilities this enables. 4556ERST 4557DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config, 4558 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \ 4559 " semihosting configuration\n", 4560QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | 4561QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV) 4562SRST 4563``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]`` 4564 Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V 4565 only). 4566 4567 Note that this allows guest direct access to the host filesystem, so 4568 should only be used with a trusted guest OS. 4569 4570 On Arm this implements the standard semihosting API, version 2.0. 4571 4572 On M68K this implements the "ColdFire GDB" interface used by 4573 libgloss. 4574 4575 Xtensa semihosting provides basic file IO calls, such as 4576 open/read/write/seek/select. Tensilica baremetal libc for ISS and 4577 linux platform "sim" use this interface. 4578 4579 On RISC-V this implements the standard semihosting API, version 0.2. 4580 4581 ``target=native|gdb|auto`` 4582 Defines where the semihosting calls will be addressed, to QEMU 4583 (``native``) or to GDB (``gdb``). The default is ``auto``, which 4584 means ``gdb`` during debug sessions and ``native`` otherwise. 4585 4586 ``chardev=str1`` 4587 Send the output to a chardev backend output for native or auto 4588 output when not in gdb 4589 4590 ``arg=str1,arg=str2,...`` 4591 Allows the user to pass input arguments, and can be used 4592 multiple times to build up a list. The old-style 4593 ``-kernel``/``-append`` method of passing a command line is 4594 still supported for backward compatibility. If both the 4595 ``--semihosting-config arg`` and the ``-kernel``/``-append`` are 4596 specified, the former is passed to semihosting as it always 4597 takes precedence. 4598ERST 4599DEF("old-param", 0, QEMU_OPTION_old_param, 4600 "-old-param old param mode\n", QEMU_ARCH_ARM) 4601SRST 4602``-old-param`` 4603 Old param mode (ARM only). 4604ERST 4605 4606DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \ 4607 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \ 4608 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \ 4609 " Enable seccomp mode 2 system call filter (default 'off').\n" \ 4610 " use 'obsolete' to allow obsolete system calls that are provided\n" \ 4611 " by the kernel, but typically no longer used by modern\n" \ 4612 " C library implementations.\n" \ 4613 " use 'elevateprivileges' to allow or deny the QEMU process ability\n" \ 4614 " to elevate privileges using set*uid|gid system calls.\n" \ 4615 " The value 'children' will deny set*uid|gid system calls for\n" \ 4616 " main QEMU process but will allow forks and execves to run unprivileged\n" \ 4617 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \ 4618 " blocking *fork and execve\n" \ 4619 " use 'resourcecontrol' to disable process affinity and schedular priority\n", 4620 QEMU_ARCH_ALL) 4621SRST 4622``-sandbox arg[,obsolete=string][,elevateprivileges=string][,spawn=string][,resourcecontrol=string]`` 4623 Enable Seccomp mode 2 system call filter. 'on' will enable syscall 4624 filtering and 'off' will disable it. The default is 'off'. 4625 4626 ``obsolete=string`` 4627 Enable Obsolete system calls 4628 4629 ``elevateprivileges=string`` 4630 Disable set\*uid\|gid system calls 4631 4632 ``spawn=string`` 4633 Disable \*fork and execve 4634 4635 ``resourcecontrol=string`` 4636 Disable process affinity and schedular priority 4637ERST 4638 4639DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig, 4640 "-readconfig <file>\n" 4641 " read config file\n", QEMU_ARCH_ALL) 4642SRST 4643``-readconfig file`` 4644 Read device configuration from file. This approach is useful when 4645 you want to spawn QEMU process with many command line options but 4646 you don't want to exceed the command line character limit. 4647ERST 4648 4649DEF("no-user-config", 0, QEMU_OPTION_nouserconfig, 4650 "-no-user-config\n" 4651 " do not load default user-provided config files at startup\n", 4652 QEMU_ARCH_ALL) 4653SRST 4654``-no-user-config`` 4655 The ``-no-user-config`` option makes QEMU not load any of the 4656 user-provided config files on sysconfdir. 4657ERST 4658 4659DEF("trace", HAS_ARG, QEMU_OPTION_trace, 4660 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n" 4661 " specify tracing options\n", 4662 QEMU_ARCH_ALL) 4663SRST 4664``-trace [[enable=]pattern][,events=file][,file=file]`` 4665 .. include:: ../qemu-option-trace.rst.inc 4666 4667ERST 4668DEF("plugin", HAS_ARG, QEMU_OPTION_plugin, 4669 "-plugin [file=]<file>[,<argname>=<argvalue>]\n" 4670 " load a plugin\n", 4671 QEMU_ARCH_ALL) 4672SRST 4673``-plugin file=file[,argname=argvalue]`` 4674 Load a plugin. 4675 4676 ``file=file`` 4677 Load the given plugin from a shared library file. 4678 4679 ``argname=argvalue`` 4680 Argument passed to the plugin. (Can be given multiple times.) 4681ERST 4682 4683HXCOMM Internal use 4684DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL) 4685DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL) 4686 4687DEF("msg", HAS_ARG, QEMU_OPTION_msg, 4688 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n" 4689 " control error message format\n" 4690 " timestamp=on enables timestamps (default: off)\n" 4691 " guest-name=on enables guest name prefix but only if\n" 4692 " -name guest option is set (default: off)\n", 4693 QEMU_ARCH_ALL) 4694SRST 4695``-msg [timestamp[=on|off]][,guest-name[=on|off]]`` 4696 Control error message format. 4697 4698 ``timestamp=on|off`` 4699 Prefix messages with a timestamp. Default is off. 4700 4701 ``guest-name=on|off`` 4702 Prefix messages with guest name but only if -name guest option is set 4703 otherwise the option is ignored. Default is off. 4704ERST 4705 4706DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate, 4707 "-dump-vmstate <file>\n" 4708 " Output vmstate information in JSON format to file.\n" 4709 " Use the scripts/vmstate-static-checker.py file to\n" 4710 " check for possible regressions in migration code\n" 4711 " by comparing two such vmstate dumps.\n", 4712 QEMU_ARCH_ALL) 4713SRST 4714``-dump-vmstate file`` 4715 Dump json-encoded vmstate information for current machine type to 4716 file in file 4717ERST 4718 4719DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile, 4720 "-enable-sync-profile\n" 4721 " enable synchronization profiling\n", 4722 QEMU_ARCH_ALL) 4723SRST 4724``-enable-sync-profile`` 4725 Enable synchronization profiling. 4726ERST 4727 4728DEFHEADING() 4729 4730DEFHEADING(Generic object creation:) 4731 4732DEF("object", HAS_ARG, QEMU_OPTION_object, 4733 "-object TYPENAME[,PROP1=VALUE1,...]\n" 4734 " create a new object of type TYPENAME setting properties\n" 4735 " in the order they are specified. Note that the 'id'\n" 4736 " property must be set. These objects are placed in the\n" 4737 " '/objects' path.\n", 4738 QEMU_ARCH_ALL) 4739SRST 4740``-object typename[,prop1=value1,...]`` 4741 Create a new object of type typename setting properties in the order 4742 they are specified. Note that the 'id' property must be set. These 4743 objects are placed in the '/objects' path. 4744 4745 ``-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`` 4746 Creates a memory file backend object, which can be used to back 4747 the guest RAM with huge pages. 4748 4749 The ``id`` parameter is a unique ID that will be used to 4750 reference this memory region in other parameters, e.g. ``-numa``, 4751 ``-device nvdimm``, etc. 4752 4753 The ``size`` option provides the size of the memory region, and 4754 accepts common suffixes, e.g. ``500M``. 4755 4756 The ``mem-path`` provides the path to either a shared memory or 4757 huge page filesystem mount. 4758 4759 The ``share`` boolean option determines whether the memory 4760 region is marked as private to QEMU, or shared. The latter 4761 allows a co-operating external process to access the QEMU memory 4762 region. 4763 4764 The ``share`` is also required for pvrdma devices due to 4765 limitations in the RDMA API provided by Linux. 4766 4767 Setting share=on might affect the ability to configure NUMA 4768 bindings for the memory backend under some circumstances, see 4769 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel 4770 source tree for additional details. 4771 4772 Setting the ``discard-data`` boolean option to on indicates that 4773 file contents can be destroyed when QEMU exits, to avoid 4774 unnecessarily flushing data to the backing file. Note that 4775 ``discard-data`` is only an optimization, and QEMU might not 4776 discard file contents if it aborts unexpectedly or is terminated 4777 using SIGKILL. 4778 4779 The ``merge`` boolean option enables memory merge, also known as 4780 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider 4781 the pages for memory deduplication. 4782 4783 Setting the ``dump`` boolean option to off excludes the memory 4784 from core dumps. This feature is also known as MADV\_DONTDUMP. 4785 4786 The ``prealloc`` boolean option enables memory preallocation. 4787 4788 The ``host-nodes`` option binds the memory range to a list of 4789 NUMA host nodes. 4790 4791 The ``policy`` option sets the NUMA policy to one of the 4792 following values: 4793 4794 ``default`` 4795 default host policy 4796 4797 ``preferred`` 4798 prefer the given host node list for allocation 4799 4800 ``bind`` 4801 restrict memory allocation to the given host node list 4802 4803 ``interleave`` 4804 interleave memory allocations across the given host node 4805 list 4806 4807 The ``align`` option specifies the base address alignment when 4808 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg 4809 ``2M``. Some backend store specified by ``mem-path`` requires an 4810 alignment different than the default one used by QEMU, eg the 4811 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In 4812 such cases, users can specify the required alignment via this 4813 option. 4814 4815 The ``pmem`` option specifies whether the backing file specified 4816 by ``mem-path`` is in host persistent memory that can be 4817 accessed using the SNIA NVM programming model (e.g. Intel 4818 NVDIMM). If ``pmem`` is set to 'on', QEMU will take necessary 4819 operations to guarantee the persistence of its own writes to 4820 ``mem-path`` (e.g. in vNVDIMM label emulation and live 4821 migration). Also, we will map the backend-file with MAP\_SYNC 4822 flag, which ensures the file metadata is in sync for 4823 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC 4824 requires support from both the host kernel (since Linux kernel 4825 4.15) and the filesystem of ``mem-path`` mounted with DAX 4826 option. 4827 4828 The ``readonly`` option specifies whether the backing file is opened 4829 read-only or read-write (default). 4830 4831 ``-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`` 4832 Creates a memory backend object, which can be used to back the 4833 guest RAM. Memory backend objects offer more control than the 4834 ``-m`` option that is traditionally used to define guest RAM. 4835 Please refer to ``memory-backend-file`` for a description of the 4836 options. 4837 4838 ``-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`` 4839 Creates an anonymous memory file backend object, which allows 4840 QEMU to share the memory with an external process (e.g. when 4841 using vhost-user). The memory is allocated with memfd and 4842 optional sealing. (Linux only) 4843 4844 The ``seal`` option creates a sealed-file, that will block 4845 further resizing the memory ('on' by default). 4846 4847 The ``hugetlb`` option specify the file to be created resides in 4848 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction 4849 with the ``hugetlb`` option, the ``hugetlbsize`` option specify 4850 the hugetlb page size on systems that support multiple hugetlb 4851 page sizes (it must be a power of 2 value supported by the 4852 system). 4853 4854 In some versions of Linux, the ``hugetlb`` option is 4855 incompatible with the ``seal`` option (requires at least Linux 4856 4.16). 4857 4858 Please refer to ``memory-backend-file`` for a description of the 4859 other options. 4860 4861 The ``share`` boolean option is on by default with memfd. 4862 4863 ``-object rng-builtin,id=id`` 4864 Creates a random number generator backend which obtains entropy 4865 from QEMU builtin functions. The ``id`` parameter is a unique ID 4866 that will be used to reference this entropy backend from the 4867 ``virtio-rng`` device. By default, the ``virtio-rng`` device 4868 uses this RNG backend. 4869 4870 ``-object rng-random,id=id,filename=/dev/random`` 4871 Creates a random number generator backend which obtains entropy 4872 from a device on the host. The ``id`` parameter is a unique ID 4873 that will be used to reference this entropy backend from the 4874 ``virtio-rng`` device. The ``filename`` parameter specifies 4875 which file to obtain entropy from and if omitted defaults to 4876 ``/dev/urandom``. 4877 4878 ``-object rng-egd,id=id,chardev=chardevid`` 4879 Creates a random number generator backend which obtains entropy 4880 from an external daemon running on the host. The ``id`` 4881 parameter is a unique ID that will be used to reference this 4882 entropy backend from the ``virtio-rng`` device. The ``chardev`` 4883 parameter is the unique ID of a character device backend that 4884 provides the connection to the RNG daemon. 4885 4886 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off`` 4887 Creates a TLS anonymous credentials object, which can be used to 4888 provide TLS support on network backends. The ``id`` parameter is 4889 a unique ID which network backends will use to access the 4890 credentials. The ``endpoint`` is either ``server`` or ``client`` 4891 depending on whether the QEMU network backend that uses the 4892 credentials will be acting as a client or as a server. If 4893 ``verify-peer`` is enabled (the default) then once the handshake 4894 is completed, the peer credentials will be verified, though this 4895 is a no-op for anonymous credentials. 4896 4897 The dir parameter tells QEMU where to find the credential files. 4898 For server endpoints, this directory may contain a file 4899 dh-params.pem providing diffie-hellman parameters to use for the 4900 TLS server. If the file is missing, QEMU will generate a set of 4901 DH parameters at startup. This is a computationally expensive 4902 operation that consumes random pool entropy, so it is 4903 recommended that a persistent set of parameters be generated 4904 upfront and saved. 4905 4906 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]`` 4907 Creates a TLS Pre-Shared Keys (PSK) credentials object, which 4908 can be used to provide TLS support on network backends. The 4909 ``id`` parameter is a unique ID which network backends will use 4910 to access the credentials. The ``endpoint`` is either ``server`` 4911 or ``client`` depending on whether the QEMU network backend that 4912 uses the credentials will be acting as a client or as a server. 4913 For clients only, ``username`` is the username which will be 4914 sent to the server. If omitted it defaults to "qemu". 4915 4916 The dir parameter tells QEMU where to find the keys file. It is 4917 called "dir/keys.psk" and contains "username:key" pairs. This 4918 file can most easily be created using the GnuTLS ``psktool`` 4919 program. 4920 4921 For server endpoints, dir may also contain a file dh-params.pem 4922 providing diffie-hellman parameters to use for the TLS server. 4923 If the file is missing, QEMU will generate a set of DH 4924 parameters at startup. This is a computationally expensive 4925 operation that consumes random pool entropy, so it is 4926 recommended that a persistent set of parameters be generated up 4927 front and saved. 4928 4929 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id`` 4930 Creates a TLS anonymous credentials object, which can be used to 4931 provide TLS support on network backends. The ``id`` parameter is 4932 a unique ID which network backends will use to access the 4933 credentials. The ``endpoint`` is either ``server`` or ``client`` 4934 depending on whether the QEMU network backend that uses the 4935 credentials will be acting as a client or as a server. If 4936 ``verify-peer`` is enabled (the default) then once the handshake 4937 is completed, the peer credentials will be verified. With x509 4938 certificates, this implies that the clients must be provided 4939 with valid client certificates too. 4940 4941 The dir parameter tells QEMU where to find the credential files. 4942 For server endpoints, this directory may contain a file 4943 dh-params.pem providing diffie-hellman parameters to use for the 4944 TLS server. If the file is missing, QEMU will generate a set of 4945 DH parameters at startup. This is a computationally expensive 4946 operation that consumes random pool entropy, so it is 4947 recommended that a persistent set of parameters be generated 4948 upfront and saved. 4949 4950 For x509 certificate credentials the directory will contain 4951 further files providing the x509 certificates. The certificates 4952 must be stored in PEM format, in filenames ca-cert.pem, 4953 ca-crl.pem (optional), server-cert.pem (only servers), 4954 server-key.pem (only servers), client-cert.pem (only clients), 4955 and client-key.pem (only clients). 4956 4957 For the server-key.pem and client-key.pem files which contain 4958 sensitive private keys, it is possible to use an encrypted 4959 version by providing the passwordid parameter. This provides the 4960 ID of a previously created ``secret`` object containing the 4961 password for decryption. 4962 4963 The priority parameter allows to override the global default 4964 priority used by gnutls. This can be useful if the system 4965 administrator needs to use a weaker set of crypto priorities for 4966 QEMU without potentially forcing the weakness onto all 4967 applications. Or conversely if one wants wants a stronger 4968 default for QEMU than for all other applications, they can do 4969 this through this parameter. Its format is a gnutls priority 4970 string as described at 4971 https://gnutls.org/manual/html_node/Priority-Strings.html. 4972 4973 ``-object tls-cipher-suites,id=id,priority=priority`` 4974 Creates a TLS cipher suites object, which can be used to control 4975 the TLS cipher/protocol algorithms that applications are permitted 4976 to use. 4977 4978 The ``id`` parameter is a unique ID which frontends will use to 4979 access the ordered list of permitted TLS cipher suites from the 4980 host. 4981 4982 The ``priority`` parameter allows to override the global default 4983 priority used by gnutls. This can be useful if the system 4984 administrator needs to use a weaker set of crypto priorities for 4985 QEMU without potentially forcing the weakness onto all 4986 applications. Or conversely if one wants wants a stronger 4987 default for QEMU than for all other applications, they can do 4988 this through this parameter. Its format is a gnutls priority 4989 string as described at 4990 https://gnutls.org/manual/html_node/Priority-Strings.html. 4991 4992 An example of use of this object is to control UEFI HTTPS Boot. 4993 The tls-cipher-suites object exposes the ordered list of permitted 4994 TLS cipher suites from the host side to the guest firmware, via 4995 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER 4996 objects. The firmware uses the IANA_TLS_CIPHER array for configuring 4997 guest-side TLS. 4998 4999 In the following example, the priority at which the host-side policy 5000 is retrieved is given by the ``priority`` property. 5001 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to 5002 refer to /etc/crypto-policies/back-ends/gnutls.config. 5003 5004 .. parsed-literal:: 5005 5006 # |qemu_system| \\ 5007 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\ 5008 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0 5009 5010 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]`` 5011 Interval t can't be 0, this filter batches the packet delivery: 5012 all packets arriving in a given interval on netdev netdevid are 5013 delayed until the end of the interval. Interval is in 5014 microseconds. ``status`` is optional that indicate whether the 5015 netfilter is on (enabled) or off (disabled), the default status 5016 for netfilter will be 'on'. 5017 5018 queue all\|rx\|tx is an option that can be applied to any 5019 netfilter. 5020 5021 ``all``: the filter is attached both to the receive and the 5022 transmit queue of the netdev (default). 5023 5024 ``rx``: the filter is attached to the receive queue of the 5025 netdev, where it will receive packets sent to the netdev. 5026 5027 ``tx``: the filter is attached to the transmit queue of the 5028 netdev, where it will receive packets sent by the netdev. 5029 5030 position head\|tail\|id=<id> is an option to specify where the 5031 filter should be inserted in the filter list. It can be applied 5032 to any netfilter. 5033 5034 ``head``: the filter is inserted at the head of the filter list, 5035 before any existing filters. 5036 5037 ``tail``: the filter is inserted at the tail of the filter list, 5038 behind any existing filters (default). 5039 5040 ``id=<id>``: the filter is inserted before or behind the filter 5041 specified by <id>, see the insert option below. 5042 5043 insert behind\|before is an option to specify where to insert 5044 the new filter relative to the one specified with 5045 position=id=<id>. It can be applied to any netfilter. 5046 5047 ``before``: insert before the specified filter. 5048 5049 ``behind``: insert behind the specified filter (default). 5050 5051 ``-object filter-mirror,id=id,netdev=netdevid,outdev=chardevid,queue=all|rx|tx[,vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5052 filter-mirror on netdev netdevid,mirror net packet to 5053 chardevchardevid, if it has the vnet\_hdr\_support flag, 5054 filter-mirror will mirror packet with vnet\_hdr\_len. 5055 5056 ``-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]`` 5057 filter-redirector on netdev netdevid,redirect filter's net 5058 packet to chardev chardevid,and redirect indev's packet to 5059 filter.if it has the vnet\_hdr\_support flag, filter-redirector 5060 will redirect packet with vnet\_hdr\_len. Create a 5061 filter-redirector we need to differ outdev id from indev id, id 5062 can not be the same. we can just use indev or outdev, but at 5063 least one of indev or outdev need to be specified. 5064 5065 ``-object filter-rewriter,id=id,netdev=netdevid,queue=all|rx|tx,[vnet_hdr_support][,position=head|tail|id=<id>][,insert=behind|before]`` 5066 Filter-rewriter is a part of COLO project.It will rewrite tcp 5067 packet to secondary from primary to keep secondary tcp 5068 connection,and rewrite tcp packet to primary from secondary make 5069 tcp packet can be handled by client.if it has the 5070 vnet\_hdr\_support flag, we can parse packet with vnet header. 5071 5072 usage: colo secondary: -object 5073 filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 -object 5074 filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 -object 5075 filter-rewriter,id=rew0,netdev=hn0,queue=all 5076 5077 ``-object filter-dump,id=id,netdev=dev[,file=filename][,maxlen=len][,position=head|tail|id=<id>][,insert=behind|before]`` 5078 Dump the network traffic on netdev dev to the file specified by 5079 filename. At most len bytes (64k by default) per packet are 5080 stored. The file format is libpcap, so it can be analyzed with 5081 tools such as tcpdump or Wireshark. 5082 5083 ``-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}]`` 5084 Colo-compare gets packet from primary\_in chardevid and 5085 secondary\_in, then compare whether the payload of primary packet 5086 and secondary packet are the same. If same, it will output 5087 primary packet to out\_dev, else it will notify COLO-framework to do 5088 checkpoint and send primary packet to out\_dev. In order to 5089 improve efficiency, we need to put the task of comparison in 5090 another iothread. If it has the vnet\_hdr\_support flag, 5091 colo compare will send/recv packet with vnet\_hdr\_len. 5092 The compare\_timeout=@var{ms} determines the maximum time of the 5093 colo-compare hold the packet. The expired\_scan\_cycle=@var{ms} 5094 is to set the period of scanning expired primary node network packets. 5095 The max\_queue\_size=@var{size} is to set the max compare queue 5096 size depend on user environment. 5097 If user want to use Xen COLO, need to add the notify\_dev to 5098 notify Xen colo-frame to do checkpoint. 5099 5100 COLO-compare must be used with the help of filter-mirror, 5101 filter-redirector and filter-rewriter. 5102 5103 :: 5104 5105 KVM COLO 5106 5107 primary: 5108 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5109 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5110 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5111 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5112 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5113 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5114 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5115 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5116 -object iothread,id=iothread1 5117 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5118 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5119 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5120 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,iothread=iothread1 5121 5122 secondary: 5123 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5124 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5125 -chardev socket,id=red0,host=3.3.3.3,port=9003 5126 -chardev socket,id=red1,host=3.3.3.3,port=9004 5127 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5128 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5129 5130 5131 Xen COLO 5132 5133 primary: 5134 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown 5135 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66 5136 -chardev socket,id=mirror0,host=3.3.3.3,port=9003,server=on,wait=off 5137 -chardev socket,id=compare1,host=3.3.3.3,port=9004,server=on,wait=off 5138 -chardev socket,id=compare0,host=3.3.3.3,port=9001,server=on,wait=off 5139 -chardev socket,id=compare0-0,host=3.3.3.3,port=9001 5140 -chardev socket,id=compare_out,host=3.3.3.3,port=9005,server=on,wait=off 5141 -chardev socket,id=compare_out0,host=3.3.3.3,port=9005 5142 -chardev socket,id=notify_way,host=3.3.3.3,port=9009,server=on,wait=off 5143 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 5144 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out 5145 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0 5146 -object iothread,id=iothread1 5147 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0,notify_dev=nofity_way,iothread=iothread1 5148 5149 secondary: 5150 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup,down script=/etc/qemu-ifdown 5151 -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 5152 -chardev socket,id=red0,host=3.3.3.3,port=9003 5153 -chardev socket,id=red1,host=3.3.3.3,port=9004 5154 -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 5155 -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 5156 5157 If you want to know the detail of above command line, you can 5158 read the colo-compare git log. 5159 5160 ``-object cryptodev-backend-builtin,id=id[,queues=queues]`` 5161 Creates a cryptodev backend which executes crypto opreation from 5162 the QEMU cipher APIS. The id parameter is a unique ID that will 5163 be used to reference this cryptodev backend from the 5164 ``virtio-crypto`` device. The queues parameter is optional, 5165 which specify the queue number of cryptodev backend, the default 5166 of queues is 1. 5167 5168 .. parsed-literal:: 5169 5170 # |qemu_system| \\ 5171 [...] \\ 5172 -object cryptodev-backend-builtin,id=cryptodev0 \\ 5173 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5174 [...] 5175 5176 ``-object cryptodev-vhost-user,id=id,chardev=chardevid[,queues=queues]`` 5177 Creates a vhost-user cryptodev backend, backed by a chardev 5178 chardevid. The id parameter is a unique ID that will be used to 5179 reference this cryptodev backend from the ``virtio-crypto`` 5180 device. The chardev should be a unix domain socket backed one. 5181 The vhost-user uses a specifically defined protocol to pass 5182 vhost ioctl replacement messages to an application on the other 5183 end of the socket. The queues parameter is optional, which 5184 specify the queue number of cryptodev backend for multiqueue 5185 vhost-user, the default of queues is 1. 5186 5187 .. parsed-literal:: 5188 5189 # |qemu_system| \\ 5190 [...] \\ 5191 -chardev socket,id=chardev0,path=/path/to/socket \\ 5192 -object cryptodev-vhost-user,id=cryptodev0,chardev=chardev0 \\ 5193 -device virtio-crypto-pci,id=crypto0,cryptodev=cryptodev0 \\ 5194 [...] 5195 5196 ``-object secret,id=id,data=string,format=raw|base64[,keyid=secretid,iv=string]`` 5197 \ 5198 ``-object secret,id=id,file=filename,format=raw|base64[,keyid=secretid,iv=string]`` 5199 Defines a secret to store a password, encryption key, or some 5200 other sensitive data. The sensitive data can either be passed 5201 directly via the data parameter, or indirectly via the file 5202 parameter. Using the data parameter is insecure unless the 5203 sensitive data is encrypted. 5204 5205 The sensitive data can be provided in raw format (the default), 5206 or base64. When encoded as JSON, the raw format only supports 5207 valid UTF-8 characters, so base64 is recommended for sending 5208 binary data. QEMU will convert from which ever format is 5209 provided to the format it needs internally. eg, an RBD password 5210 can be provided in raw format, even though it will be base64 5211 encoded when passed onto the RBD sever. 5212 5213 For added protection, it is possible to encrypt the data 5214 associated with a secret using the AES-256-CBC cipher. Use of 5215 encryption is indicated by providing the keyid and iv 5216 parameters. The keyid parameter provides the ID of a previously 5217 defined secret that contains the AES-256 decryption key. This 5218 key should be 32-bytes long and be base64 encoded. The iv 5219 parameter provides the random initialization vector used for 5220 encryption of this particular secret and should be a base64 5221 encrypted string of the 16-byte IV. 5222 5223 The simplest (insecure) usage is to provide the secret inline 5224 5225 .. parsed-literal:: 5226 5227 # |qemu_system| -object secret,id=sec0,data=letmein,format=raw 5228 5229 The simplest secure usage is to provide the secret via a file 5230 5231 # printf "letmein" > mypasswd.txt # QEMU\_SYSTEM\_MACRO -object 5232 secret,id=sec0,file=mypasswd.txt,format=raw 5233 5234 For greater security, AES-256-CBC should be used. To illustrate 5235 usage, consider the openssl command line tool which can encrypt 5236 the data. Note that when encrypting, the plaintext must be 5237 padded to the cipher block size (32 bytes) using the standard 5238 PKCS#5/6 compatible padding algorithm. 5239 5240 First a master key needs to be created in base64 encoding: 5241 5242 :: 5243 5244 # openssl rand -base64 32 > key.b64 5245 # KEY=$(base64 -d key.b64 | hexdump -v -e '/1 "%02X"') 5246 5247 Each secret to be encrypted needs to have a random 5248 initialization vector generated. These do not need to be kept 5249 secret 5250 5251 :: 5252 5253 # openssl rand -base64 16 > iv.b64 5254 # IV=$(base64 -d iv.b64 | hexdump -v -e '/1 "%02X"') 5255 5256 The secret to be defined can now be encrypted, in this case 5257 we're telling openssl to base64 encode the result, but it could 5258 be left as raw bytes if desired. 5259 5260 :: 5261 5262 # SECRET=$(printf "letmein" | 5263 openssl enc -aes-256-cbc -a -K $KEY -iv $IV) 5264 5265 When launching QEMU, create a master secret pointing to 5266 ``key.b64`` and specify that to be used to decrypt the user 5267 password. Pass the contents of ``iv.b64`` to the second secret 5268 5269 .. parsed-literal:: 5270 5271 # |qemu_system| \\ 5272 -object secret,id=secmaster0,format=base64,file=key.b64 \\ 5273 -object secret,id=sec0,keyid=secmaster0,format=base64,\\ 5274 data=$SECRET,iv=$(<iv.b64) 5275 5276 ``-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]`` 5277 Create a Secure Encrypted Virtualization (SEV) guest object, 5278 which can be used to provide the guest memory encryption support 5279 on AMD processors. 5280 5281 When memory encryption is enabled, one of the physical address 5282 bit (aka the C-bit) is utilized to mark if a memory page is 5283 protected. The ``cbitpos`` is used to provide the C-bit 5284 position. The C-bit position is Host family dependent hence user 5285 must provide this value. On EPYC, the value should be 47. 5286 5287 When memory encryption is enabled, we loose certain bits in 5288 physical address space. The ``reduced-phys-bits`` is used to 5289 provide the number of bits we loose in physical address space. 5290 Similar to C-bit, the value is Host family dependent. On EPYC, 5291 the value should be 5. 5292 5293 The ``sev-device`` provides the device file to use for 5294 communicating with the SEV firmware running inside AMD Secure 5295 Processor. The default device is '/dev/sev'. If hardware 5296 supports memory encryption then /dev/sev devices are created by 5297 CCP driver. 5298 5299 The ``policy`` provides the guest policy to be enforced by the 5300 SEV firmware and restrict what configuration and operational 5301 commands can be performed on this guest by the hypervisor. The 5302 policy should be provided by the guest owner and is bound to the 5303 guest and cannot be changed throughout the lifetime of the 5304 guest. The default is 0. 5305 5306 If guest ``policy`` allows sharing the key with another SEV 5307 guest then ``handle`` can be use to provide handle of the guest 5308 from which to share the key. 5309 5310 The ``dh-cert-file`` and ``session-file`` provides the guest 5311 owner's Public Diffie-Hillman key defined in SEV spec. The PDH 5312 and session parameters are used for establishing a cryptographic 5313 session with the guest owner to negotiate keys used for 5314 attestation. The file must be encoded in base64. 5315 5316 The ``kernel-hashes`` adds the hashes of given kernel/initrd/ 5317 cmdline to a designated guest firmware page for measured Linux 5318 boot with -kernel. The default is off. (Since 6.2) 5319 5320 e.g to launch a SEV guest 5321 5322 .. parsed-literal:: 5323 5324 # |qemu_system_x86| \\ 5325 ...... \\ 5326 -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \\ 5327 -machine ...,memory-encryption=sev0 \\ 5328 ..... 5329 5330 ``-object authz-simple,id=id,identity=string`` 5331 Create an authorization object that will control access to 5332 network services. 5333 5334 The ``identity`` parameter is identifies the user and its format 5335 depends on the network service that authorization object is 5336 associated with. For authorizing based on TLS x509 certificates, 5337 the identity must be the x509 distinguished name. Note that care 5338 must be taken to escape any commas in the distinguished name. 5339 5340 An example authorization object to validate a x509 distinguished 5341 name would look like: 5342 5343 .. parsed-literal:: 5344 5345 # |qemu_system| \\ 5346 ... \\ 5347 -object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\ 5348 ... 5349 5350 Note the use of quotes due to the x509 distinguished name 5351 containing whitespace, and escaping of ','. 5352 5353 ``-object authz-listfile,id=id,filename=path,refresh=on|off`` 5354 Create an authorization object that will control access to 5355 network services. 5356 5357 The ``filename`` parameter is the fully qualified path to a file 5358 containing the access control list rules in JSON format. 5359 5360 An example set of rules that match against SASL usernames might 5361 look like: 5362 5363 :: 5364 5365 { 5366 "rules": [ 5367 { "match": "fred", "policy": "allow", "format": "exact" }, 5368 { "match": "bob", "policy": "allow", "format": "exact" }, 5369 { "match": "danb", "policy": "deny", "format": "glob" }, 5370 { "match": "dan*", "policy": "allow", "format": "exact" }, 5371 ], 5372 "policy": "deny" 5373 } 5374 5375 When checking access the object will iterate over all the rules 5376 and the first rule to match will have its ``policy`` value 5377 returned as the result. If no rules match, then the default 5378 ``policy`` value is returned. 5379 5380 The rules can either be an exact string match, or they can use 5381 the simple UNIX glob pattern matching to allow wildcards to be 5382 used. 5383 5384 If ``refresh`` is set to true the file will be monitored and 5385 automatically reloaded whenever its content changes. 5386 5387 As with the ``authz-simple`` object, the format of the identity 5388 strings being matched depends on the network service, but is 5389 usually a TLS x509 distinguished name, or a SASL username. 5390 5391 An example authorization object to validate a SASL username 5392 would look like: 5393 5394 .. parsed-literal:: 5395 5396 # |qemu_system| \\ 5397 ... \\ 5398 -object authz-simple,id=auth0,filename=/etc/qemu/vnc-sasl.acl,refresh=on \\ 5399 ... 5400 5401 ``-object authz-pam,id=id,service=string`` 5402 Create an authorization object that will control access to 5403 network services. 5404 5405 The ``service`` parameter provides the name of a PAM service to 5406 use for authorization. It requires that a file 5407 ``/etc/pam.d/service`` exist to provide the configuration for 5408 the ``account`` subsystem. 5409 5410 An example authorization object to validate a TLS x509 5411 distinguished name would look like: 5412 5413 .. parsed-literal:: 5414 5415 # |qemu_system| \\ 5416 ... \\ 5417 -object authz-pam,id=auth0,service=qemu-vnc \\ 5418 ... 5419 5420 There would then be a corresponding config file for PAM at 5421 ``/etc/pam.d/qemu-vnc`` that contains: 5422 5423 :: 5424 5425 account requisite pam_listfile.so item=user sense=allow \ 5426 file=/etc/qemu/vnc.allow 5427 5428 Finally the ``/etc/qemu/vnc.allow`` file would contain the list 5429 of x509 distingished names that are permitted access 5430 5431 :: 5432 5433 CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB 5434 5435 ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch`` 5436 Creates a dedicated event loop thread that devices can be 5437 assigned to. This is known as an IOThread. By default device 5438 emulation happens in vCPU threads or the main event loop thread. 5439 This can become a scalability bottleneck. IOThreads allow device 5440 emulation and I/O to run on other host CPUs. 5441 5442 The ``id`` parameter is a unique ID that will be used to 5443 reference this IOThread from ``-device ...,iothread=id``. 5444 Multiple devices can be assigned to an IOThread. Note that not 5445 all devices support an ``iothread`` parameter. 5446 5447 The ``query-iothreads`` QMP command lists IOThreads and reports 5448 their thread IDs so that the user can configure host CPU 5449 pinning/affinity. 5450 5451 IOThreads use an adaptive polling algorithm to reduce event loop 5452 latency. Instead of entering a blocking system call to monitor 5453 file descriptors and then pay the cost of being woken up when an 5454 event occurs, the polling algorithm spins waiting for events for 5455 a short time. The algorithm's default parameters are suitable 5456 for many cases but can be adjusted based on knowledge of the 5457 workload and/or host device latency. 5458 5459 The ``poll-max-ns`` parameter is the maximum number of 5460 nanoseconds to busy wait for events. Polling can be disabled by 5461 setting this value to 0. 5462 5463 The ``poll-grow`` parameter is the multiplier used to increase 5464 the polling time when the algorithm detects it is missing events 5465 due to not polling long enough. 5466 5467 The ``poll-shrink`` parameter is the divisor used to decrease 5468 the polling time when the algorithm detects it is spending too 5469 long polling without encountering events. 5470 5471 The ``aio-max-batch`` parameter is the maximum number of requests 5472 in a batch for the AIO engine, 0 means that the engine will use 5473 its default. 5474 5475 The IOThread parameters can be modified at run-time using the 5476 ``qom-set`` command (where ``iothread1`` is the IOThread's 5477 ``id``): 5478 5479 :: 5480 5481 (qemu) qom-set /objects/iothread1 poll-max-ns 100000 5482ERST 5483 5484 5485HXCOMM This is the last statement. Insert new options before this line! 5486 5487#undef DEF 5488#undef DEFHEADING 5489#undef ARCHHEADING 5490
