1 HXCOMM Use
DEFHEADING() to define headings
in both help text and rST
.
2 HXCOMM Text between SRST and ERST is copied to the rST version and
3 HXCOMM discarded from C version
.
4 HXCOMM
DEF(option
, HAS_ARG
/0, opt_enum
, opt_help
, arch_mask
) is used to
5 HXCOMM construct option structures
, enums and help message
for specified
7 HXCOMM HXCOMM can be used
for comments
, discarded from both rST and C
.
9 DEFHEADING(Standard options
:)
11 DEF("help", 0, QEMU_OPTION_h
,
12 "-h or -help display this help and exit\n", QEMU_ARCH_ALL
)
18 DEF("version", 0, QEMU_OPTION_version
,
19 "-version display version information and exit\n", QEMU_ARCH_ALL
)
22 Display version information and exit
25 DEF("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, 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",
42 ``
-machine
[type
=]name
[,prop
=value
[,...]]``
43 Select the emulated machine by name
. Use ``
-machine help`` to list
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
.
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
.
57 Supported machine properties are
:
59 ``accel
=accels1
[:accels2
[:...]]``
60 This is used to enable an accelerator
. Depending on the target
61 architecture
, kvm
, xen
, hax
, hvf
, 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
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
.
71 ``dump
-guest
-core
=on|off``
72 Include guest memory
in a core dump
. The
default is on
.
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).
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
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
92 Enables or disables NVDIMM support
. The
default is off
.
94 ``memory
-encryption
=``
95 Memory encryption object to use
. The
default is none
.
98 Enables or disables ACPI Heterogeneous Memory Attribute Table
99 (HMAT
) support
. The
default is off
.
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
.
107 -object memory
-backend
-file
,id
=pc
.ram
,size
=512M
,mem
-path
=/hugetlbfs
,prealloc
=on
,share
=on
108 -machine memory
-backend
=pc
.ram
111 Migration compatibility note
:
112 a
) as backend id one shall use value of
'default-ram-id', advertised by
113 machine
type (available via ``query
-machines`` QMP command
), if migration
114 to
/from old
QEMU (<5.0) is expected
.
115 b
) for machine types
4.0 and older
, user shall
116 use ``x
-use
-canonical
-path
-for-ramblock
-id
=off`` backend option
117 if migration to
/from old
QEMU (<5.0) is expected
.
120 -object memory
-backend
-ram
,id
=pc
.ram
,size
=512M
,x
-use
-canonical
-path
-for-ramblock
-id
=off
121 -machine memory
-backend
=pc
.ram
125 HXCOMM Deprecated by
-machine
126 DEF("M", HAS_ARG
, QEMU_OPTION_M
, "", QEMU_ARCH_ALL
)
128 DEF("cpu", HAS_ARG
, QEMU_OPTION_cpu
,
129 "-cpu cpu select CPU ('-cpu help' for list)\n", QEMU_ARCH_ALL
)
132 Select CPU
model (``
-cpu help``
for list and additional feature
136 DEF("accel", HAS_ARG
, QEMU_OPTION_accel
,
137 "-accel [accel=]accelerator[,prop[=value][,...]]\n"
138 " select accelerator (kvm, xen, hax, hvf, whpx or tcg; use 'help' for a list)\n"
139 " igd-passthru=on|off (enable Xen integrated Intel graphics passthrough, default=off)\n"
140 " kernel-irqchip=on|off|split controls accelerated irqchip support (default=on)\n"
141 " kvm-shadow-mem=size of KVM shadow MMU in bytes\n"
142 " split-wx=on|off (enable TCG split w^x mapping)\n"
143 " tb-size=n (TCG translation block cache size)\n"
144 " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL
)
146 ``
-accel name
[,prop
=value
[,...]]``
147 This is used to enable an accelerator
. Depending on the target
148 architecture
, kvm
, xen
, hax
, hvf
, whpx or tcg can be available
. By
149 default, tcg is used
. If there is more than one accelerator
150 specified
, the next one is used
if the previous one fails to
153 ``igd
-passthru
=on|off``
154 When Xen is
in use
, this option controls whether Intel
155 integrated graphics devices can be passed through to the guest
158 ``kernel
-irqchip
=on|off|split``
159 Controls KVM
in-kernel irqchip support
. The
default is full
160 acceleration of the interrupt controllers
. On x86
, split irqchip
161 reduces the kernel attack surface
, at a performance cost
for
162 non
-MSI interrupts
. Disabling the
in-kernel irqchip completely
163 is not recommended except
for debugging purposes
.
165 ``kvm
-shadow
-mem
=size``
166 Defines the size of the KVM shadow MMU
.
169 Controls the use of split w^x mapping
for the TCG code generation
170 buffer
. Some operating systems require
this to be enabled
, and
in
171 such a
case this will
default on
. On other operating systems
, this
172 will
default off
, but one may enable
this for testing or debugging
.
175 Controls the
size (in MiB
) of the TCG translation block cache
.
177 ``thread
=single|multi``
178 Controls number of TCG threads
. When the TCG is multi
-threaded
179 there will be one thread per vCPU therefore taking advantage of
180 additional host cores
. The
default is to enable multi
-threading
181 where both the back
-end and front
-ends support it and no
182 incompatible TCG features have been
enabled (e
.g
.
186 DEF("smp", HAS_ARG
, QEMU_OPTION_smp
,
187 "-smp [cpus=]n[,maxcpus=cpus][,cores=cores][,threads=threads][,dies=dies][,sockets=sockets]\n"
188 " set the number of CPUs to 'n' [default=1]\n"
189 " maxcpus= maximum number of total cpus, including\n"
190 " offline CPUs for hotplug, etc\n"
191 " cores= number of CPU cores on one socket (for PC, it's on one die)\n"
192 " threads= number of threads on one CPU core\n"
193 " dies= number of CPU dies on one socket (for PC only)\n"
194 " sockets= number of discrete sockets in the system\n",
197 ``
-smp
[cpus
=]n
[,cores
=cores
][,threads
=threads
][,dies
=dies
][,sockets
=sockets
][,maxcpus
=maxcpus
]``
198 Simulate an SMP system with n CPUs
. On the PC target
, up to
255 CPUs
199 are supported
. On Sparc32 target
, Linux limits the number of usable
200 CPUs to
4. For the PC target
, the number of cores per die
, the
201 number of threads per cores
, the number of dies per packages and the
202 total number of sockets can be specified
. Missing values will be
203 computed
. If any on the three values is given
, the total number of
204 CPUs n can be omitted
. maxcpus specifies the maximum number of
208 DEF("numa", HAS_ARG
, QEMU_OPTION_numa
,
209 "-numa node[,mem=size][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
210 "-numa node[,memdev=id][,cpus=firstcpu[-lastcpu]][,nodeid=node][,initiator=node]\n"
211 "-numa dist,src=source,dst=destination,val=distance\n"
212 "-numa cpu,node-id=node[,socket-id=x][,core-id=y][,thread-id=z]\n"
213 "-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"
214 "-numa hmat-cache,node-id=node,size=size,level=level[,associativity=none|direct|complex][,policy=none|write-back|write-through][,line=size]\n",
217 ``
-numa node
[,mem
=size
][,cpus
=firstcpu
[-lastcpu
]][,nodeid
=node
][,initiator
=initiator
]``
219 ``
-numa node
[,memdev
=id
][,cpus
=firstcpu
[-lastcpu
]][,nodeid
=node
][,initiator
=initiator
]``
221 ``
-numa dist
,src
=source
,dst
=destination
,val
=distance``
223 ``
-numa cpu
,node
-id
=node
[,socket
-id
=x
][,core
-id
=y
][,thread
-id
=z
]``
225 ``
-numa hmat
-lb
,initiator
=node
,target
=node
,hierarchy
=hierarchy
,data
-type
=tpye
[,latency
=lat
][,bandwidth
=bw
]``
227 ``
-numa hmat
-cache
,node
-id
=node
,size
=size
,level
=level
[,associativity
=str
][,policy
=str
][,line
=size
]``
228 Define a NUMA node and assign RAM and VCPUs to it
. Set the NUMA
229 distance from a source node to a destination node
. Set the ACPI
230 Heterogeneous Memory Attributes
for the given nodes
.
232 Legacy VCPU assignment uses
'\ ``cpus``\ ' option where firstcpu and
233 lastcpu are CPU indexes
. Each
'\ ``cpus``\ ' option represent a
234 contiguous range of CPU
indexes (or a single VCPU
if lastcpu is
235 omitted
). A non
-contiguous set of VCPUs can be represented by
236 providing multiple
'\ ``cpus``\ ' options
. If
'\ ``cpus``\ ' is
237 omitted on all nodes
, VCPUs are automatically split between them
.
239 For example
, the following option assigns VCPUs
0, 1, 2 and
5 to a
244 -numa node
,cpus
=0-2,cpus
=5
246 '\ ``cpu``\ ' option is a
new alternative to
'\ ``cpus``\ ' option
247 which uses
'\ ``socket-id|core-id|thread-id``\ ' properties to
248 assign CPU objects to a node
using topology layout properties of
249 CPU
. The set of properties is machine specific
, and depends on used
250 machine type
/'\ ``smp``\ ' options
. It could be queried with
251 '\ ``hotpluggable-cpus``\ ' monitor command
. '\ ``node-id``\ '
252 property specifies node to which CPU object will be assigned
, it
's
253 required for node to be declared with '\ ``node``\
' option before
254 it's used with
'\ ``cpu``\ ' option
.
261 -smp
1,sockets
=2,maxcpus
=2 \
262 -numa node
,nodeid
=0 -numa node
,nodeid
=1 \
263 -numa cpu
,node
-id
=0,socket
-id
=0 -numa cpu
,node
-id
=1,socket
-id
=1
265 Legacy
'\ ``mem``\ ' assigns a given RAM amount to a
node (not supported
266 for 5.1 and newer machine types
). '\ ``memdev``\ ' assigns RAM from
267 a given memory backend device to a node
. If
'\ ``mem``\ ' and
268 '\ ``memdev``\ ' are omitted
in all nodes
, RAM is split equally between them
.
271 '\ ``mem``\ ' and
'\ ``memdev``\ ' are mutually exclusive
.
272 Furthermore
, if one node uses
'\ ``memdev``\ ', all of them have to
275 '\ ``initiator``\ ' is an additional option that points to an
276 initiator NUMA node that has best
performance (the lowest latency or
277 largest bandwidth
) to
this NUMA node
. Note that
this option can be
278 set only when the machine property
'hmat' is set to
'on'.
280 Following example creates a machine with
2 NUMA nodes
, node
0 has
281 CPU
. node
1 has only memory
, and its initiator is node
0. Note that
282 because node
0 has CPU
, by
default the initiator of node
0 is itself
288 -m
2G
,slots
=2,maxmem
=4G \
289 -object memory
-backend
-ram
,size
=1G
,id
=m0 \
290 -object memory
-backend
-ram
,size
=1G
,id
=m1 \
291 -numa node
,nodeid
=0,memdev
=m0 \
292 -numa node
,nodeid
=1,memdev
=m1
,initiator
=0 \
293 -smp
2,sockets
=2,maxcpus
=2 \
294 -numa cpu
,node
-id
=0,socket
-id
=0 \
295 -numa cpu
,node
-id
=0,socket
-id
=1
297 source and destination are NUMA node IDs
. distance is the NUMA
298 distance from source to destination
. The distance from a node to
299 itself is always
10. If any pair of nodes is given a distance
, then
300 all pairs must be given distances
. Although
, when distances are only
301 given
in one direction
for each pair of nodes
, then the distances
in
302 the opposite directions are assumed to be the same
. If
, however
, an
303 asymmetrical pair of distances is given
for even one node pair
, then
304 all node pairs must be provided distance values
for both directions
,
305 even when they are symmetrical
. When a node is unreachable from
306 another node
, set the pair
's distance to 255.
308 Note that the -``numa`` option doesn't allocate any of the specified
309 resources
, it just assigns existing resources to NUMA nodes
. This
310 means that one still has to use the ``
-m``
, ``
-smp`` options to
311 allocate RAM and VCPUs respectively
.
313 Use
'\ ``hmat-lb``\ ' to set System Locality Latency and Bandwidth
314 Information between initiator and target NUMA nodes
in ACPI
315 Heterogeneous Attribute Memory
Table (HMAT
). Initiator NUMA node can
316 create memory requests
, usually it has one or more processors
.
317 Target NUMA node contains addressable memory
.
319 In
'\ ``hmat-lb``\ ' option
, node are NUMA node IDs
. hierarchy is
320 the memory hierarchy of the target NUMA node
: if hierarchy is
321 'memory', the structure represents the memory performance
; if
322 hierarchy is
'first-level\|second-level\|third-level', this
323 structure represents aggregated performance of memory side caches
324 for each domain
. type of
'data-type' is type of data represented by
325 this structure instance
: if 'hierarchy' is
'memory', 'data-type' is
326 'access\|read\|write' latency or
'access\|read\|write' bandwidth of
327 the target memory
; if 'hierarchy' is
328 'first-level\|second-level\|third-level', 'data-type' is
329 'access\|read\|write' hit latency or
'access\|read\|write' hit
330 bandwidth of the target memory side cache
.
332 lat is latency value
in nanoseconds
. bw is bandwidth value
, the
333 possible value and units are NUM
[M\|G\|T
], mean that the bandwidth
334 value are NUM byte per
second (or MB
/s
, GB
/s or TB
/s depending on
335 used suffix
). Note that
if latency or bandwidth value is
0, means
336 the corresponding latency or bandwidth information is not provided
.
338 In
'\ ``hmat-cache``\ ' option
, node
-id is the NUMA
-id of the memory
339 belongs
. size is the size of memory side cache
in bytes
. level is
340 the cache level described
in this structure
, note that the cache
341 level
0 should not be used with
'\ ``hmat-cache``\ ' option
.
342 associativity is the cache associativity
, the possible value is
343 'none/direct(direct-mapped)/complex(complex cache indexing)'. policy
344 is the write policy
. line is the cache Line size
in bytes
.
346 For example
, the following options describe
2 NUMA nodes
. Node
0 has
347 2 cpus and a ram
, node
1 has only a ram
. The processors
in node
0
348 access memory
in node
0 with access
-latency
5 nanoseconds
,
349 access
-bandwidth is
200 MB
/s
; The processors
in NUMA node
0 access
350 memory
in NUMA node
1 with access
-latency
10 nanoseconds
,
351 access
-bandwidth is
100 MB
/s
. And
for memory side cache information
,
352 NUMA node
0 and
1 both have
1 level memory cache
, size is
10KB
,
353 policy is write
-back
, the cache Line size is
8 bytes
:
359 -object memory
-backend
-ram
,size
=1G
,id
=m0 \
360 -object memory
-backend
-ram
,size
=1G
,id
=m1 \
362 -numa node
,nodeid
=0,memdev
=m0 \
363 -numa node
,nodeid
=1,memdev
=m1
,initiator
=0 \
364 -numa cpu
,node
-id
=0,socket
-id
=0 \
365 -numa cpu
,node
-id
=0,socket
-id
=1 \
366 -numa hmat
-lb
,initiator
=0,target
=0,hierarchy
=memory
,data
-type
=access
-latency
,latency
=5 \
367 -numa hmat
-lb
,initiator
=0,target
=0,hierarchy
=memory
,data
-type
=access
-bandwidth
,bandwidth
=200M \
368 -numa hmat
-lb
,initiator
=0,target
=1,hierarchy
=memory
,data
-type
=access
-latency
,latency
=10 \
369 -numa hmat
-lb
,initiator
=0,target
=1,hierarchy
=memory
,data
-type
=access
-bandwidth
,bandwidth
=100M \
370 -numa hmat
-cache
,node
-id
=0,size
=10K
,level
=1,associativity
=direct
,policy
=write
-back
,line
=8 \
371 -numa hmat
-cache
,node
-id
=1,size
=10K
,level
=1,associativity
=direct
,policy
=write
-back
,line
=8
374 DEF("add-fd", HAS_ARG
, QEMU_OPTION_add_fd
,
375 "-add-fd fd=fd,set=set[,opaque=opaque]\n"
376 " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL
)
378 ``
-add
-fd fd
=fd
,set
=set
[,opaque
=opaque
]``
379 Add a file descriptor to an fd set
. Valid options are
:
382 This option defines the file descriptor of which a duplicate is
383 added to fd set
. The file descriptor cannot be stdin
, stdout
, or
387 This option defines the ID of the fd set to add the file
391 This option defines a free
-form string that can be used to
394 You can open an image
using pre
-opened file descriptors from an fd
400 -add
-fd fd
=3,set
=2,opaque
="rdwr:/path/to/file" \\
401 -add
-fd fd
=4,set
=2,opaque
="rdonly:/path/to/file" \\
402 -drive file
=/dev
/fdset
/2,index
=0,media
=disk
405 DEF("set", HAS_ARG
, QEMU_OPTION_set
,
406 "-set group.id.arg=value\n"
407 " set <arg> parameter for item <id> of type <group>\n"
408 " i.e. -set drive.$id.file=/path/to/image\n", QEMU_ARCH_ALL
)
410 ``
-set group
.id
.arg
=value``
411 Set parameter arg
for item id of type group
414 DEF("global", HAS_ARG
, QEMU_OPTION_global
,
415 "-global driver.property=value\n"
416 "-global driver=driver,property=property,value=value\n"
417 " set a global default for a driver property\n",
420 ``
-global driver
.prop
=value``
422 ``
-global driver
=driver
,property
=property
,value
=value``
423 Set
default value of driver
's property prop to value, e.g.:
427 |qemu_system_x86| -global ide-hd.physical_block_size=4096 disk-image.img
429 In particular, you can use this to set driver properties for devices
430 which are created automatically by the machine model. To create a
431 device which is not created automatically and set properties on it,
434 -global driver.prop=value is shorthand for -global
435 driver=driver,property=prop,value=value. The longhand syntax works
436 even when driver contains a dot.
439 DEF("boot", HAS_ARG, QEMU_OPTION_boot,
440 "-boot [order=drives][,once=drives][,menu=on|off]\n"
441 " [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time][,strict=on|off]\n"
442 " 'drives
': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
443 " 'sp_name
': the file's name that would be passed to bios as logo picture
, if menu
=on
\n"
444 " 'sp_time': the period that splash picture last
if menu
=on
, unit is ms
\n"
445 " 'rb_timeout': the timeout before guest reboot when boot failed
, unit is ms
\n",
448 ``-boot [order=drives][,once=drives][,menu=on|off][,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_timeout][,strict=on|off]``
449 Specify boot order drives as a string of drive letters. Valid drive
450 letters depend on the target architecture. The x86 PC uses: a, b
451 (floppy 1 and 2), c (first hard disk), d (first CD-ROM), n-p
452 (Etherboot from network adapter 1-4), hard disk boot is the default.
453 To apply a particular boot order only on the first startup, specify
454 it via ``once``. Note that the ``order`` or ``once`` parameter
455 should not be used together with the ``bootindex`` property of
456 devices, since the firmware implementations normally do not support
457 both at the same time.
459 Interactive boot menus/prompts can be enabled via ``menu=on`` as far
460 as firmware/BIOS supports them. The default is non-interactive boot.
462 A splash picture could be passed to bios, enabling user to show it
463 as logo, when option splash=sp\_name is given and menu=on, If
464 firmware/BIOS supports them. Currently Seabios for X86 system
465 support it. limitation: The splash file could be a jpeg file or a
466 BMP file in 24 BPP format(true color). The resolution should be
467 supported by the SVGA mode, so the recommended is 320x240, 640x480,
470 A timeout could be passed to bios, guest will pause for rb\_timeout
471 ms when boot failed, then reboot. If rb\_timeout is '-1', guest will
472 not reboot, qemu passes '-1' to bios by default. Currently Seabios
473 for X86 system support it.
475 Do strict boot via ``strict=on`` as far as firmware/BIOS supports
476 it. This only effects when boot priority is changed by bootindex
477 options. The default is non-strict boot.
481 # try to boot from network first, then from hard disk
482 |qemu_system_x86| -boot order=nc
483 # boot from CD-ROM first, switch back to default order after reboot
484 |qemu_system_x86| -boot once=d
485 # boot with a splash picture for 5 seconds.
486 |qemu_system_x86| -boot menu=on,splash=/root/boot.bmp,splash-time=5000
488 Note: The legacy format '-boot drives' is still supported but its
489 use is discouraged as it may be removed from future versions.
492 DEF("m
", HAS_ARG, QEMU_OPTION_m,
493 "-m
[size
=]megs
[,slots
=n
,maxmem
=size
]\n"
494 " configure guest RAM
\n"
495 " size
: initial amount of guest memory
\n"
496 " slots
: number of hotplug
slots (default: none
)\n"
497 " maxmem
: maximum amount of guest
memory (default: none
)\n"
498 "NOTE
: Some architectures might enforce a specific granularity
\n",
501 ``-m [size=]megs[,slots=n,maxmem=size]``
502 Sets guest startup RAM size to megs megabytes. Default is 128 MiB.
503 Optionally, a suffix of "M
" or "G
" can be used to signify a value in
504 megabytes or gigabytes respectively. Optional pair slots, maxmem
505 could be used to set amount of hotpluggable memory slots and maximum
506 amount of memory. Note that maxmem must be aligned to the page size.
508 For example, the following command-line sets the guest startup RAM
509 size to 1GB, creates 3 slots to hotplug additional memory and sets
510 the maximum memory the guest can reach to 4GB:
514 |qemu_system| -m 1G,slots=3,maxmem=4G
516 If slots and maxmem are not specified, memory hotplug won't be
517 enabled and the guest startup RAM will never increase.
520 DEF("mem
-path
", HAS_ARG, QEMU_OPTION_mempath,
521 "-mem
-path FILE provide backing storage
for guest RAM
\n", QEMU_ARCH_ALL)
524 Allocate guest RAM from a temporarily created file in path.
527 DEF("mem
-prealloc
", 0, QEMU_OPTION_mem_prealloc,
528 "-mem
-prealloc preallocate guest
memory (use with
-mem
-path
)\n",
532 Preallocate memory when using -mem-path.
535 DEF("k
", HAS_ARG, QEMU_OPTION_k,
536 "-k language use keyboard
layout (for example
'fr' for French
)\n",
540 Use keyboard layout language (for example ``fr`` for French). This
541 option is only needed where it is not easy to get raw PC keycodes
542 (e.g. on Macs, with some X11 servers or with a VNC or curses
543 display). You don't normally need to use it on PC/Linux or
546 The available layouts are:
550 ar de-ch es fo fr-ca hu ja mk no pt-br sv
551 da en-gb et fr fr-ch is lt nl pl ru th
552 de en-us fi fr-be hr it lv nl-be pt sl tr
554 The default is ``en-us``.
558 HXCOMM Deprecated by -audiodev
559 DEF("audio
-help
", 0, QEMU_OPTION_audio_help,
560 "-audio
-help show
-audiodev equivalent of the currently specified audio settings
\n",
564 Will show the -audiodev equivalent of the currently specified
565 (deprecated) environment variables.
568 DEF("audiodev
", HAS_ARG, QEMU_OPTION_audiodev,
569 "-audiodev
[driver
=]driver
,id
=id
[,prop
[=value
][,...]]\n"
570 " specifies the audio backend to use
\n"
571 " id
= identifier of the backend
\n"
572 " timer
-period
= timer period
in microseconds
\n"
573 " in|out
.mixing
-engine
= use mixing engine to mix streams inside QEMU
\n"
574 " in|out
.fixed
-settings
= use fixed settings
for host audio
\n"
575 " in|out
.frequency
= frequency to use with fixed settings
\n"
576 " in|out
.channels
= number of channels to use with fixed settings
\n"
577 " in|out
.format
= sample format to use with fixed settings
\n"
578 " valid values
: s8
, s16
, s32
, u8
, u16
, u32
, f32
\n"
579 " in|out
.voices
= number of voices to use
\n"
580 " in|out
.buffer
-length
= length of buffer
in microseconds
\n"
581 "-audiodev none
,id
=id
,[,prop
[=value
][,...]]\n"
582 " dummy driver that discards all output
\n"
583 #ifdef CONFIG_AUDIO_ALSA
584 "-audiodev alsa
,id
=id
[,prop
[=value
][,...]]\n"
585 " in|out
.dev
= name of the audio device to use
\n"
586 " in|out
.period
-length
= length of period
in microseconds
\n"
587 " in|out
.try-poll
= attempt to use poll mode
\n"
588 " threshold
= threshold (in microseconds
) when playback starts
\n"
590 #ifdef CONFIG_AUDIO_COREAUDIO
591 "-audiodev coreaudio
,id
=id
[,prop
[=value
][,...]]\n"
592 " in|out
.buffer
-count
= number of buffers
\n"
594 #ifdef CONFIG_AUDIO_DSOUND
595 "-audiodev dsound
,id
=id
[,prop
[=value
][,...]]\n"
596 " latency
= add extra latency to playback
in microseconds
\n"
598 #ifdef CONFIG_AUDIO_OSS
599 "-audiodev oss
,id
=id
[,prop
[=value
][,...]]\n"
600 " in|out
.dev
= path of the audio device to use
\n"
601 " in|out
.buffer
-count
= number of buffers
\n"
602 " in|out
.try-poll
= attempt to use poll mode
\n"
603 " try-mmap
= try using memory mapped access
\n"
604 " exclusive
= open device
in exclusive mode
\n"
605 " dsp
-policy
= set timing
policy (0..10), -1 to use fragment mode
\n"
607 #ifdef CONFIG_AUDIO_PA
608 "-audiodev pa
,id
=id
[,prop
[=value
][,...]]\n"
609 " server
= PulseAudio server address
\n"
610 " in|out
.name
= source
/sink device name
\n"
611 " in|out
.latency
= desired latency
in microseconds
\n"
613 #ifdef CONFIG_AUDIO_SDL
614 "-audiodev sdl
,id
=id
[,prop
[=value
][,...]]\n"
615 " in|out
.buffer
-count
= number of buffers
\n"
618 "-audiodev spice
,id
=id
[,prop
[=value
][,...]]\n"
620 "-audiodev wav
,id
=id
[,prop
[=value
][,...]]\n"
621 " path
= path of wav file to record
\n",
624 ``-audiodev [driver=]driver,id=id[,prop[=value][,...]]``
625 Adds a new audio backend driver identified by id. There are global
626 and driver specific properties. Some values can be set differently
627 for input and output, they're marked with ``in|out.``. You can set
628 the input's property with ``in.prop`` and the output's property with
629 ``out.prop``. For example:
633 -audiodev alsa,id=example,in.frequency=44110,out.frequency=8000
634 -audiodev alsa,id=example,out.channels=1 # leaves in.channels unspecified
636 NOTE: parameter validation is known to be incomplete, in many cases
637 specifying an invalid option causes QEMU to print an error message
638 and continue emulation without sound.
640 Valid global options are:
643 Identifies the audio backend.
645 ``timer-period=period``
646 Sets the timer period used by the audio subsystem in
647 microseconds. Default is 10000 (10 ms).
649 ``in|out.mixing-engine=on|off``
650 Use QEMU's mixing engine to mix all streams inside QEMU and
651 convert audio formats when not supported by the backend. When
652 off, fixed-settings must be off too. Note that disabling this
653 option means that the selected backend must support multiple
654 streams and the audio formats used by the virtual cards,
655 otherwise you'll get no sound. It's not recommended to disable
656 this option unless you want to use 5.1 or 7.1 audio, as mixing
657 engine only supports mono and stereo audio. Default is on.
659 ``in|out.fixed-settings=on|off``
660 Use fixed settings for host audio. When off, it will change
661 based on how the guest opens the sound card. In this case you
662 must not specify frequency, channels or format. Default is on.
664 ``in|out.frequency=frequency``
665 Specify the frequency to use when using fixed-settings. Default
668 ``in|out.channels=channels``
669 Specify the number of channels to use when using fixed-settings.
670 Default is 2 (stereo).
672 ``in|out.format=format``
673 Specify the sample format to use when using fixed-settings.
674 Valid values are: ``s8``, ``s16``, ``s32``, ``u8``, ``u16``,
675 ``u32``, ``f32``. Default is ``s16``.
677 ``in|out.voices=voices``
678 Specify the number of voices to use. Default is 1.
680 ``in|out.buffer-length=usecs``
681 Sets the size of the buffer in microseconds.
683 ``-audiodev none,id=id[,prop[=value][,...]]``
684 Creates a dummy backend that discards all outputs. This backend has
685 no backend specific properties.
687 ``-audiodev alsa,id=id[,prop[=value][,...]]``
688 Creates backend using the ALSA. This backend is only available on
691 ALSA specific options are:
693 ``in|out.dev=device``
694 Specify the ALSA device to use for input and/or output. Default
697 ``in|out.period-length=usecs``
698 Sets the period length in microseconds.
700 ``in|out.try-poll=on|off``
701 Attempt to use poll mode with the device. Default is on.
703 ``threshold=threshold``
704 Threshold (in microseconds) when playback starts. Default is 0.
706 ``-audiodev coreaudio,id=id[,prop[=value][,...]]``
707 Creates a backend using Apple's Core Audio. This backend is only
708 available on Mac OS and only supports playback.
710 Core Audio specific options are:
712 ``in|out.buffer-count=count``
713 Sets the count of the buffers.
715 ``-audiodev dsound,id=id[,prop[=value][,...]]``
716 Creates a backend using Microsoft's DirectSound. This backend is
717 only available on Windows and only supports playback.
719 DirectSound specific options are:
722 Add extra usecs microseconds latency to playback. Default is
725 ``-audiodev oss,id=id[,prop[=value][,...]]``
726 Creates a backend using OSS. This backend is available on most
729 OSS specific options are:
731 ``in|out.dev=device``
732 Specify the file name of the OSS device to use. Default is
735 ``in|out.buffer-count=count``
736 Sets the count of the buffers.
738 ``in|out.try-poll=on|of``
739 Attempt to use poll mode with the device. Default is on.
742 Try using memory mapped device access. Default is off.
745 Open the device in exclusive mode (vmix won't work in this
746 case). Default is off.
748 ``dsp-policy=policy``
749 Sets the timing policy (between 0 and 10, where smaller number
750 means smaller latency but higher CPU usage). Use -1 to use
751 buffer sizes specified by ``buffer`` and ``buffer-count``. This
752 option is ignored if you do not have OSS 4. Default is 5.
754 ``-audiodev pa,id=id[,prop[=value][,...]]``
755 Creates a backend using PulseAudio. This backend is available on
758 PulseAudio specific options are:
761 Sets the PulseAudio server to connect to.
764 Use the specified source/sink for recording/playback.
766 ``in|out.latency=usecs``
767 Desired latency in microseconds. The PulseAudio server will try
768 to honor this value but actual latencies may be lower or higher.
770 ``-audiodev sdl,id=id[,prop[=value][,...]]``
771 Creates a backend using SDL. This backend is available on most
772 systems, but you should use your platform's native backend if
775 SDL specific options are:
777 ``in|out.buffer-count=count``
778 Sets the count of the buffers.
780 ``-audiodev spice,id=id[,prop[=value][,...]]``
781 Creates a backend that sends audio through SPICE. This backend
782 requires ``-spice`` and automatically selected in that case, so
783 usually you can ignore this option. This backend has no backend
786 ``-audiodev wav,id=id[,prop[=value][,...]]``
787 Creates a backend that writes audio to a WAV file.
789 Backend specific options are:
792 Write recorded audio into the specified file. Default is
796 DEF("soundhw
", HAS_ARG, QEMU_OPTION_soundhw,
797 "-soundhw c1
,... enable audio support
\n"
798 " and only specified sound
cards (comma separated list
)\n"
799 " use
'-soundhw help' to get the list of supported cards
\n"
800 " use
'-soundhw all' to enable all of them
\n", QEMU_ARCH_ALL)
802 ``-soundhw card1[,card2,...] or -soundhw all``
803 Enable audio and selected sound hardware. Use 'help' to print all
804 available sound hardware. For example:
808 |qemu_system_x86| -soundhw sb16,adlib disk.img
809 |qemu_system_x86| -soundhw es1370 disk.img
810 |qemu_system_x86| -soundhw ac97 disk.img
811 |qemu_system_x86| -soundhw hda disk.img
812 |qemu_system_x86| -soundhw all disk.img
813 |qemu_system_x86| -soundhw help
815 Note that Linux's i810\_audio OSS kernel (for AC97) module might
816 require manually specifying clocking.
820 modprobe i810_audio clocking=48000
823 DEF("device
", HAS_ARG, QEMU_OPTION_device,
824 "-device driver
[,prop
[=value
][,...]]\n"
825 " add
device (based on driver
)\n"
826 " prop
=value
,... sets driver properties
\n"
827 " use
'-device help' to print all possible drivers
\n"
828 " use
'-device driver,help' to print all possible properties
\n",
831 ``-device driver[,prop[=value][,...]]``
832 Add device driver. prop=value sets driver properties. Valid
833 properties depend on the driver. To get help on possible drivers and
834 properties, use ``-device help`` and ``-device driver,help``.
838 ``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]``
839 Add an IPMI BMC. This is a simulation of a hardware management
840 interface processor that normally sits on a system. It provides a
841 watchdog and the ability to reset and power control the system. You
842 need to connect this to an IPMI interface to make it useful
844 The IPMI slave address to use for the BMC. The default is 0x20. This
845 address is the BMC's address on the I2C network of management
846 controllers. If you don't know what this means, it is safe to ignore
850 The BMC id for interfaces to use this device.
853 Define slave address to use for the BMC. The default is 0x20.
856 file containing raw Sensor Data Records (SDR) data. The default
860 size of a Field Replaceable Unit (FRU) area. The default is
864 file containing raw Field Replaceable Unit (FRU) inventory data.
868 value for the GUID for the BMC, in standard UUID format. If this
869 is set, get "Get GUID
" command to the BMC will return it.
870 Otherwise "Get GUID
" will return an error.
872 ``-device ipmi-bmc-extern,id=id,chardev=id[,slave_addr=val]``
873 Add a connection to an external IPMI BMC simulator. Instead of
874 locally emulating the BMC like the above item, instead connect to an
875 external entity that provides the IPMI services.
877 A connection is made to an external BMC simulator. If you do this,
878 it is strongly recommended that you use the "reconnect
=" chardev
879 option to reconnect to the simulator if the connection is lost. Note
880 that if this is not used carefully, it can be a security issue, as
881 the interface has the ability to send resets, NMIs, and power off
882 the VM. It's best if QEMU makes a connection to an external
883 simulator running on a secure port on localhost, so neither the
884 simulator nor QEMU is exposed to any outside network.
886 See the "lanserv
/README
.vm
" file in the OpenIPMI library for more
887 details on the external interface.
889 ``-device isa-ipmi-kcs,bmc=id[,ioport=val][,irq=val]``
890 Add a KCS IPMI interafce on the ISA bus. This also adds a
891 corresponding ACPI and SMBIOS entries, if appropriate.
894 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern
898 Define the I/O address of the interface. The default is 0xca0
902 Define the interrupt to use. The default is 5. To disable
903 interrupts, set this to 0.
905 ``-device isa-ipmi-bt,bmc=id[,ioport=val][,irq=val]``
906 Like the KCS interface, but defines a BT interface. The default port
907 is 0xe4 and the default interrupt is 5.
909 ``-device pci-ipmi-kcs,bmc=id``
910 Add a KCS IPMI interafce on the PCI bus.
913 The BMC to connect to, one of ipmi-bmc-sim or ipmi-bmc-extern above.
915 ``-device pci-ipmi-bt,bmc=id``
916 Like the KCS interface, but defines a BT interface on the PCI bus.
919 DEF("name
", HAS_ARG, QEMU_OPTION_name,
920 "-name string1
[,process
=string2
][,debug
-threads
=on|off
]\n"
921 " set the name of the guest
\n"
922 " string1 sets the window title and string2 the process name
\n"
923 " When debug
-threads is enabled
, individual threads are given a separate name
\n"
924 " NOTE
: The thread names are
for debugging and not a stable API
.\n",
928 Sets the name of the guest. This name will be displayed in the SDL
929 window caption. The name will also be used for the VNC server. Also
930 optionally set the top visible process name in Linux. Naming of
931 individual threads can also be enabled on Linux to aid debugging.
934 DEF("uuid
", HAS_ARG, QEMU_OPTION_uuid,
935 "-uuid
%08x
-%04x
-%04x
-%04x
-%012x
\n"
936 " specify machine UUID
\n", QEMU_ARCH_ALL)
944 DEFHEADING(Block device options:)
946 DEF("fda
", HAS_ARG, QEMU_OPTION_fda,
947 "-fda
/-fdb file use
'file' as floppy disk
0/1 image
\n", QEMU_ARCH_ALL)
948 DEF("fdb
", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
953 Use file as floppy disk 0/1 image (see the :ref:`disk images` chapter in
954 the System Emulation Users Guide).
957 DEF("hda
", HAS_ARG, QEMU_OPTION_hda,
958 "-hda
/-hdb file use
'file' as IDE hard disk
0/1 image
\n", QEMU_ARCH_ALL)
959 DEF("hdb
", HAS_ARG, QEMU_OPTION_hdb, "", QEMU_ARCH_ALL)
960 DEF("hdc
", HAS_ARG, QEMU_OPTION_hdc,
961 "-hdc
/-hdd file use
'file' as IDE hard disk
2/3 image
\n", QEMU_ARCH_ALL)
962 DEF("hdd
", HAS_ARG, QEMU_OPTION_hdd, "", QEMU_ARCH_ALL)
971 Use file as hard disk 0, 1, 2 or 3 image (see the :ref:`disk images`
972 chapter in the System Emulation Users Guide).
975 DEF("cdrom
", HAS_ARG, QEMU_OPTION_cdrom,
976 "-cdrom file use
'file' as IDE cdrom
image (cdrom is ide1 master
)\n",
980 Use file as CD-ROM image (you cannot use ``-hdc`` and ``-cdrom`` at
981 the same time). You can use the host CD-ROM by using ``/dev/cdrom``
985 DEF("blockdev
", HAS_ARG, QEMU_OPTION_blockdev,
986 "-blockdev
[driver
=]driver
[,node
-name
=N
][,discard
=ignore|unmap
]\n"
987 " [,cache
.direct
=on|off
][,cache
.no
-flush
=on|off
]\n"
988 " [,read
-only
=on|off
][,auto
-read
-only
=on|off
]\n"
989 " [,force
-share
=on|off
][,detect
-zeroes
=on|off|unmap
]\n"
990 " [,driver specific parameters
...]\n"
991 " configure a block backend
\n", QEMU_ARCH_ALL)
993 ``-blockdev option[,option[,option[,...]]]``
994 Define a new block driver node. Some of the options apply to all
995 block drivers, other options are only accepted for a specific block
996 driver. See below for a list of generic options and options for the
997 most common block drivers.
999 Options that expect a reference to another node (e.g. ``file``) can
1000 be given in two ways. Either you specify the node name of an already
1001 existing node (file=node-name), or you define a new node inline,
1002 adding options for the referenced node after a dot
1003 (file.filename=path,file.aio=native).
1005 A block driver node created with ``-blockdev`` can be used for a
1006 guest device by specifying its node name for the ``drive`` property
1007 in a ``-device`` argument that defines a block device.
1009 ``Valid options for any block driver node:``
1011 Specifies the block driver to use for the given node.
1014 This defines the name of the block driver node by which it
1015 will be referenced later. The name must be unique, i.e. it
1016 must not match the name of a different block driver node, or
1017 (if you use ``-drive`` as well) the ID of a drive.
1019 If no node name is specified, it is automatically generated.
1020 The generated node name is not intended to be predictable
1021 and changes between QEMU invocations. For the top level, an
1022 explicit node name must be specified.
1025 Open the node read-only. Guest write attempts will fail.
1027 Note that some block drivers support only read-only access,
1028 either generally or in certain configurations. In this case,
1029 the default value ``read-only=off`` does not work and the
1030 option must be specified explicitly.
1033 If ``auto-read-only=on`` is set, QEMU may fall back to
1034 read-only usage even when ``read-only=off`` is requested, or
1035 even switch between modes as needed, e.g. depending on
1036 whether the image file is writable or whether a writing user
1037 is attached to the node.
1040 Override the image locking system of QEMU by forcing the
1041 node to utilize weaker shared access for permissions where
1042 it would normally request exclusive access. When there is
1043 the potential for multiple instances to have the same file
1044 open (whether this invocation of QEMU is the first or the
1045 second instance), both instances must permit shared access
1046 for the second instance to succeed at opening the file.
1048 Enabling ``force-share=on`` requires ``read-only=on``.
1051 The host page cache can be avoided with ``cache.direct=on``.
1052 This will attempt to do disk IO directly to the guest's
1053 memory. QEMU may still perform an internal copy of the data.
1056 In case you don't care about data integrity over host
1057 failures, you can use ``cache.no-flush=on``. This option
1058 tells QEMU that it never needs to write any data to the disk
1059 but can instead keep things in cache. If anything goes
1060 wrong, like your host losing power, the disk storage getting
1061 disconnected accidentally, etc. your image will most
1062 probably be rendered unusable.
1065 discard is one of "ignore
" (or "off
") or "unmap
" (or "on
")
1066 and controls whether ``discard`` (also known as ``trim`` or
1067 ``unmap``) requests are ignored or passed to the filesystem.
1068 Some machine types may not support discard requests.
1070 ``detect-zeroes=detect-zeroes``
1071 detect-zeroes is "off
", "on
" or "unmap
" and enables the
1072 automatic conversion of plain zero writes by the OS to
1073 driver specific optimized zero write commands. You may even
1074 choose "unmap
" if discard is set to "unmap
" to allow a zero
1075 write to be converted to an ``unmap`` operation.
1077 ``Driver-specific options for file``
1078 This is the protocol-level block driver for accessing regular
1082 The path to the image file in the local filesystem
1085 Specifies the AIO backend (threads/native/io_uring,
1089 Specifies whether the image file is protected with Linux OFD
1090 / POSIX locks. The default is to use the Linux Open File
1091 Descriptor API if available, otherwise no lock is applied.
1092 (auto/on/off, default: auto)
1098 -blockdev driver=file,node-name=disk,filename=disk.img
1100 ``Driver-specific options for raw``
1101 This is the image format block driver for raw images. It is
1102 usually stacked on top of a protocol level block driver such as
1106 Reference to or definition of the data source block driver
1107 node (e.g. a ``file`` driver node)
1113 -blockdev driver=file,node-name=disk_file,filename=disk.img
1114 -blockdev driver=raw,node-name=disk,file=disk_file
1120 -blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
1122 ``Driver-specific options for qcow2``
1123 This is the image format block driver for qcow2 images. It is
1124 usually stacked on top of a protocol level block driver such as
1128 Reference to or definition of the data source block driver
1129 node (e.g. a ``file`` driver node)
1132 Reference to or definition of the backing file block device
1133 (default is taken from the image file). It is allowed to
1134 pass ``null`` here in order to disable the default backing
1138 Whether to enable the lazy refcounts feature (on/off;
1139 default is taken from the image file)
1142 The maximum total size of the L2 table and refcount block
1143 caches in bytes (default: the sum of l2-cache-size and
1144 refcount-cache-size)
1147 The maximum size of the L2 table cache in bytes (default: if
1148 cache-size is not specified - 32M on Linux platforms, and 8M
1149 on non-Linux platforms; otherwise, as large as possible
1150 within the cache-size, while permitting the requested or the
1151 minimal refcount cache size)
1153 ``refcount-cache-size``
1154 The maximum size of the refcount block cache in bytes
1155 (default: 4 times the cluster size; or if cache-size is
1156 specified, the part of it which is not used for the L2
1159 ``cache-clean-interval``
1160 Clean unused entries in the L2 and refcount caches. The
1161 interval is in seconds. The default value is 600 on
1162 supporting platforms, and 0 on other platforms. Setting it
1163 to 0 disables this feature.
1165 ``pass-discard-request``
1166 Whether discard requests to the qcow2 device should be
1167 forwarded to the data source (on/off; default: on if
1168 discard=unmap is specified, off otherwise)
1170 ``pass-discard-snapshot``
1171 Whether discard requests for the data source should be
1172 issued when a snapshot operation (e.g. deleting a snapshot)
1173 frees clusters in the qcow2 file (on/off; default: on)
1175 ``pass-discard-other``
1176 Whether discard requests for the data source should be
1177 issued on other occasions where a cluster gets freed
1178 (on/off; default: off)
1181 Which overlap checks to perform for writes to the image
1182 (none/constant/cached/all; default: cached). For details or
1183 finer granularity control refer to the QAPI documentation of
1190 -blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
1191 -blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
1197 -blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
1199 ``Driver-specific options for other drivers``
1200 Please refer to the QAPI documentation of the ``blockdev-add``
1204 DEF("drive
", HAS_ARG, QEMU_OPTION_drive,
1205 "-drive
[file
=file
][,if=type
][,bus
=n
][,unit
=m
][,media
=d
][,index
=i
]\n"
1206 " [,cache
=writethrough|writeback|none|directsync|unsafe
][,format
=f
]\n"
1207 " [,snapshot
=on|off
][,rerror
=ignore|stop|report
]\n"
1208 " [,werror
=ignore|stop|report|enospc
][,id
=name
]\n"
1209 " [,aio
=threads|native|io_uring
]\n"
1210 " [,readonly
=on|off
][,copy
-on
-read
=on|off
]\n"
1211 " [,discard
=ignore|unmap
][,detect
-zeroes
=on|off|unmap
]\n"
1212 " [[,bps
=b
]|
[[,bps_rd
=r
][,bps_wr
=w
]]]\n"
1213 " [[,iops
=i
]|
[[,iops_rd
=r
][,iops_wr
=w
]]]\n"
1214 " [[,bps_max
=bm
]|
[[,bps_rd_max
=rm
][,bps_wr_max
=wm
]]]\n"
1215 " [[,iops_max
=im
]|
[[,iops_rd_max
=irm
][,iops_wr_max
=iwm
]]]\n"
1216 " [[,iops_size
=is
]]\n"
1218 " use
'file' as a drive image
\n", QEMU_ARCH_ALL)
1220 ``-drive option[,option[,option[,...]]]``
1221 Define a new drive. This includes creating a block driver node (the
1222 backend) as well as a guest device, and is mostly a shortcut for
1223 defining the corresponding ``-blockdev`` and ``-device`` options.
1225 ``-drive`` accepts all options that are accepted by ``-blockdev``.
1226 In addition, it knows the following options:
1229 This option defines which disk image (see the :ref:`disk images`
1230 chapter in the System Emulation Users Guide) to use with this drive.
1231 If the filename contains comma, you must double it (for instance,
1232 "file
=my
,,file
" to use file "my
,file
").
1234 Special files such as iSCSI devices can be specified using
1235 protocol specific URLs. See the section for "Device URL Syntax
"
1236 for more information.
1239 This option defines on which type on interface the drive is
1240 connected. Available types are: ide, scsi, sd, mtd, floppy,
1241 pflash, virtio, none.
1243 ``bus=bus,unit=unit``
1244 These options define where is connected the drive by defining
1245 the bus number and the unit id.
1248 This option defines where is connected the drive by using an
1249 index in the list of available connectors of a given interface
1253 This option defines the type of the media: disk or cdrom.
1255 ``snapshot=snapshot``
1256 snapshot is "on
" or "off
" and controls snapshot mode for the
1257 given drive (see ``-snapshot``).
1260 cache is "none
", "writeback
", "unsafe
", "directsync
" or
1261 "writethrough
" and controls how the host cache is used to access
1262 block data. This is a shortcut that sets the ``cache.direct``
1263 and ``cache.no-flush`` options (as in ``-blockdev``), and
1264 additionally ``cache.writeback``, which provides a default for
1265 the ``write-cache`` option of block guest devices (as in
1266 ``-device``). The modes correspond to the following settings:
1268 ============= =============== ============ ==============
1269 \ cache.writeback cache.direct cache.no-flush
1270 ============= =============== ============ ==============
1271 writeback on off off
1273 writethrough off off off
1274 directsync off on off
1276 ============= =============== ============ ==============
1278 The default mode is ``cache=writeback``.
1281 aio is "threads
", "native
", or "io_uring
" and selects between pthread
1282 based disk I/O, native Linux AIO, or Linux io_uring API.
1285 Specify which disk format will be used rather than detecting the
1286 format. Can be used to specify format=raw to avoid interpreting
1287 an untrusted format header.
1289 ``werror=action,rerror=action``
1290 Specify which action to take on write and read errors. Valid
1291 actions are: "ignore
" (ignore the error and try to continue),
1292 "stop
" (pause QEMU), "report
" (report the error to the guest),
1293 "enospc
" (pause QEMU only if the host disk is full; report the
1294 error to the guest otherwise). The default setting is
1295 ``werror=enospc`` and ``rerror=report``.
1297 ``copy-on-read=copy-on-read``
1298 copy-on-read is "on
" or "off
" and enables whether to copy read
1299 backing file sectors into the image file.
1301 ``bps=b,bps_rd=r,bps_wr=w``
1302 Specify bandwidth throttling limits in bytes per second, either
1303 for all request types or for reads or writes only. Small values
1304 can lead to timeouts or hangs inside the guest. A safe minimum
1305 for disks is 2 MB/s.
1307 ``bps_max=bm,bps_rd_max=rm,bps_wr_max=wm``
1308 Specify bursts in bytes per second, either for all request types
1309 or for reads or writes only. Bursts allow the guest I/O to spike
1310 above the limit temporarily.
1312 ``iops=i,iops_rd=r,iops_wr=w``
1313 Specify request rate limits in requests per second, either for
1314 all request types or for reads or writes only.
1316 ``iops_max=bm,iops_rd_max=rm,iops_wr_max=wm``
1317 Specify bursts in requests per second, either for all request
1318 types or for reads or writes only. Bursts allow the guest I/O to
1319 spike above the limit temporarily.
1322 Let every is bytes of a request count as a new request for iops
1323 throttling purposes. Use this option to prevent guests from
1324 circumventing iops limits by sending fewer but larger requests.
1327 Join a throttling quota group with given name g. All drives that
1328 are members of the same group are accounted for together. Use
1329 this option to prevent guests from circumventing throttling
1330 limits by using many small disks instead of a single larger
1333 By default, the ``cache.writeback=on`` mode is used. It will report
1334 data writes as completed as soon as the data is present in the host
1335 page cache. This is safe as long as your guest OS makes sure to
1336 correctly flush disk caches where needed. If your guest OS does not
1337 handle volatile disk write caches correctly and your host crashes or
1338 loses power, then the guest may experience data corruption.
1340 For such guests, you should consider using ``cache.writeback=off``.
1341 This means that the host page cache will be used to read and write
1342 data, but write notification will be sent to the guest only after
1343 QEMU has made sure to flush each write to the disk. Be aware that
1344 this has a major impact on performance.
1346 When using the ``-snapshot`` option, unsafe caching is always used.
1348 Copy-on-read avoids accessing the same backing file sectors
1349 repeatedly and is useful when the backing file is over a slow
1350 network. By default copy-on-read is off.
1352 Instead of ``-cdrom`` you can use:
1356 |qemu_system| -drive file=file,index=2,media=cdrom
1358 Instead of ``-hda``, ``-hdb``, ``-hdc``, ``-hdd``, you can use:
1362 |qemu_system| -drive file=file,index=0,media=disk
1363 |qemu_system| -drive file=file,index=1,media=disk
1364 |qemu_system| -drive file=file,index=2,media=disk
1365 |qemu_system| -drive file=file,index=3,media=disk
1367 You can open an image using pre-opened file descriptors from an fd
1373 -add-fd fd=3,set=2,opaque="rdwr
:/path
/to
/file
" \\
1374 -add-fd fd=4,set=2,opaque="rdonly
:/path
/to
/file
" \\
1375 -drive file=/dev/fdset/2,index=0,media=disk
1377 You can connect a CDROM to the slave of ide0:
1381 |qemu_system_x86| -drive file=file,if=ide,index=1,media=cdrom
1383 If you don't specify the "file
=" argument, you define an empty
1388 |qemu_system_x86| -drive if=ide,index=1,media=cdrom
1390 Instead of ``-fda``, ``-fdb``, you can use:
1394 |qemu_system_x86| -drive file=file,index=0,if=floppy
1395 |qemu_system_x86| -drive file=file,index=1,if=floppy
1397 By default, interface is "ide
" and index is automatically
1402 |qemu_system_x86| -drive file=a -drive file=b"
1404 is interpreted like
:
1408 |qemu_system_x86|
-hda a
-hdb b
1411 DEF("mtdblock", HAS_ARG
, QEMU_OPTION_mtdblock
,
1412 "-mtdblock file use 'file' as on-board Flash memory image\n",
1416 Use file as on
-board Flash memory image
.
1419 DEF("sd", HAS_ARG
, QEMU_OPTION_sd
,
1420 "-sd file use 'file' as SecureDigital card image\n", QEMU_ARCH_ALL
)
1423 Use file as SecureDigital card image
.
1426 DEF("pflash", HAS_ARG
, QEMU_OPTION_pflash
,
1427 "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL
)
1430 Use file as a parallel flash image
.
1433 DEF("snapshot", 0, QEMU_OPTION_snapshot
,
1434 "-snapshot write to temporary files instead of disk image files\n",
1438 Write to temporary files instead of disk image files
. In
this case,
1439 the raw disk image you use is not written back
. You can however
1440 force the write back by pressing C
-a
s (see the
:ref
:`disk images`
1441 chapter
in the System Emulation Users Guide
).
1444 DEF("fsdev", HAS_ARG
, QEMU_OPTION_fsdev
,
1445 "-fsdev local,id=id,path=path,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1446 " [,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode]\n"
1447 " [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
1448 " [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
1449 " [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
1450 " [[,throttling.iops-total-max=im]|[[,throttling.iops-read-max=irm][,throttling.iops-write-max=iwm]]]\n"
1451 " [[,throttling.iops-size=is]]\n"
1452 "-fsdev proxy,id=id,socket=socket[,writeout=immediate][,readonly=on]\n"
1453 "-fsdev proxy,id=id,sock_fd=sock_fd[,writeout=immediate][,readonly=on]\n"
1454 "-fsdev synth,id=id\n",
1458 ``
-fsdev local
,id
=id
,path
=path
,security_model
=security_model
[,writeout
=writeout
][,readonly
=on
][,fmode
=fmode
][,dmode
=dmode
] [,throttling
.option
=value
[,throttling
.option
=value
[,...]]]``
1460 ``
-fsdev proxy
,id
=id
,socket
=socket
[,writeout
=writeout
][,readonly
=on
]``
1462 ``
-fsdev proxy
,id
=id
,sock_fd
=sock_fd
[,writeout
=writeout
][,readonly
=on
]``
1464 ``
-fsdev synth
,id
=id
[,readonly
=on
]``
1465 Define a
new file system device
. Valid options are
:
1468 Accesses to the filesystem are done by QEMU
.
1471 Accesses to the filesystem are done by virtfs
-proxy
-helper(1).
1474 Synthetic filesystem
, only used by QTests
.
1477 Specifies identifier
for this device
.
1480 Specifies the export path
for the file system device
. Files
1481 under
this path will be available to the
9p client on the guest
.
1483 ``security_model
=security_model``
1484 Specifies the security model to be used
for this export path
.
1485 Supported security models are
"passthrough", "mapped-xattr",
1486 "mapped-file" and
"none". In
"passthrough" security model
, files
1487 are stored
using the same credentials as they are created on the
1488 guest
. This requires QEMU to run as root
. In
"mapped-xattr"
1489 security model
, some of the file attributes like uid
, gid
, mode
1490 bits and link target are stored as file attributes
. For
1491 "mapped-file" these attributes are stored
in the hidden
1492 .virtfs\_metadata directory
. Directories exported by
this
1493 security model cannot interact with other unix tools
. "none"
1494 security model is same as passthrough except the sever won
't
1495 report failures if it fails to set file attributes like
1496 ownership. Security model is mandatory only for local fsdriver.
1497 Other fsdrivers (like proxy) don't take security model as a
1500 ``writeout
=writeout``
1501 This is an optional argument
. The only supported value is
1502 "immediate". This means that host page cache will be used to
1503 read and write data but write notification will be sent to the
1504 guest only when the data has been reported as written by the
1508 Enables exporting
9p share as a readonly mount
for guests
. By
1509 default read
-write access is given
.
1512 Enables proxy filesystem driver to use passed socket file
for
1513 communicating with virtfs
-proxy
-helper(1).
1516 Enables proxy filesystem driver to use passed socket descriptor
1517 for communicating with virtfs
-proxy
-helper(1). Usually a helper
1518 like libvirt will create socketpair and pass one of the fds as
1522 Specifies the
default mode
for newly created files on the host
.
1523 Works only with security models
"mapped-xattr" and
1527 Specifies the
default mode
for newly created directories on the
1528 host
. Works only with security models
"mapped-xattr" and
1531 ``throttling
.bps
-total
=b
,throttling
.bps
-read
=r
,throttling
.bps
-write
=w``
1532 Specify bandwidth throttling limits
in bytes per second
, either
1533 for all request types or
for reads or writes only
.
1535 ``throttling
.bps
-total
-max
=bm
,bps
-read
-max
=rm
,bps
-write
-max
=wm``
1536 Specify bursts
in bytes per second
, either
for all request types
1537 or
for reads or writes only
. Bursts allow the guest I
/O to spike
1538 above the limit temporarily
.
1540 ``throttling
.iops
-total
=i
,throttling
.iops
-read
=r
, throttling
.iops
-write
=w``
1541 Specify request rate limits
in requests per second
, either
for
1542 all request types or
for reads or writes only
.
1544 ``throttling
.iops
-total
-max
=im
,throttling
.iops
-read
-max
=irm
, throttling
.iops
-write
-max
=iwm``
1545 Specify bursts
in requests per second
, either
for all request
1546 types or
for reads or writes only
. Bursts allow the guest I
/O to
1547 spike above the limit temporarily
.
1549 ``throttling
.iops
-size
=is``
1550 Let every is bytes of a request count as a
new request
for iops
1551 throttling purposes
.
1553 -fsdev option is used along with
-device driver
"virtio-9p-...".
1555 ``
-device virtio
-9p
-type
,fsdev
=id
,mount_tag
=mount_tag``
1556 Options
for virtio
-9p
-... driver are
:
1559 Specifies the variant to be used
. Supported values are
"pci",
1560 "ccw" or
"device", depending on the machine type
.
1563 Specifies the id value specified along with
-fsdev option
.
1565 ``mount_tag
=mount_tag``
1566 Specifies the tag name to be used by the guest to mount
this
1570 DEF("virtfs", HAS_ARG
, QEMU_OPTION_virtfs
,
1571 "-virtfs local,path=path,mount_tag=tag,security_model=mapped-xattr|mapped-file|passthrough|none\n"
1572 " [,id=id][,writeout=immediate][,readonly=on][,fmode=fmode][,dmode=dmode][,multidevs=remap|forbid|warn]\n"
1573 "-virtfs proxy,mount_tag=tag,socket=socket[,id=id][,writeout=immediate][,readonly=on]\n"
1574 "-virtfs proxy,mount_tag=tag,sock_fd=sock_fd[,id=id][,writeout=immediate][,readonly=on]\n"
1575 "-virtfs synth,mount_tag=tag[,id=id][,readonly=on]\n",
1579 ``
-virtfs local
,path
=path
,mount_tag
=mount_tag
,security_model
=security_model
[,writeout
=writeout
][,readonly
=on
] [,fmode
=fmode
][,dmode
=dmode
][,multidevs
=multidevs
]``
1581 ``
-virtfs proxy
,socket
=socket
,mount_tag
=mount_tag
[,writeout
=writeout
][,readonly
=on
]``
1583 ``
-virtfs proxy
,sock_fd
=sock_fd
,mount_tag
=mount_tag
[,writeout
=writeout
][,readonly
=on
]``
1585 ``
-virtfs synth
,mount_tag
=mount_tag``
1586 Define a
new virtual filesystem device and expose it to the guest
using
1587 a virtio
-9p
-device (a
.k
.a
. 9pfs
), which essentially means that a certain
1588 directory on host is made directly accessible by guest as a pass
-through
1589 file system by
using the
9P network protocol
for communication between
1590 host and guests
, if desired even accessible
, shared by several guests
1593 Note that ``
-virtfs`` is actually just a convenience shortcut
for its
1594 generalized form ``
-fsdev
-device virtio
-9p
-pci``
.
1596 The general form of pass
-through file system options are
:
1599 Accesses to the filesystem are done by QEMU
.
1602 Accesses to the filesystem are done by virtfs
-proxy
-helper(1).
1605 Synthetic filesystem
, only used by QTests
.
1608 Specifies identifier
for the filesystem device
1611 Specifies the export path
for the file system device
. Files
1612 under
this path will be available to the
9p client on the guest
.
1614 ``security_model
=security_model``
1615 Specifies the security model to be used
for this export path
.
1616 Supported security models are
"passthrough", "mapped-xattr",
1617 "mapped-file" and
"none". In
"passthrough" security model
, files
1618 are stored
using the same credentials as they are created on the
1619 guest
. This requires QEMU to run as root
. In
"mapped-xattr"
1620 security model
, some of the file attributes like uid
, gid
, mode
1621 bits and link target are stored as file attributes
. For
1622 "mapped-file" these attributes are stored
in the hidden
1623 .virtfs\_metadata directory
. Directories exported by
this
1624 security model cannot interact with other unix tools
. "none"
1625 security model is same as passthrough except the sever won
't
1626 report failures if it fails to set file attributes like
1627 ownership. Security model is mandatory only for local fsdriver.
1628 Other fsdrivers (like proxy) don't take security model as a
1631 ``writeout
=writeout``
1632 This is an optional argument
. The only supported value is
1633 "immediate". This means that host page cache will be used to
1634 read and write data but write notification will be sent to the
1635 guest only when the data has been reported as written by the
1639 Enables exporting
9p share as a readonly mount
for guests
. By
1640 default read
-write access is given
.
1643 Enables proxy filesystem driver to use passed socket file
for
1644 communicating with virtfs
-proxy
-helper(1). Usually a helper like
1645 libvirt will create socketpair and pass one of the fds as
1649 Enables proxy filesystem driver to use passed
'sock\_fd' as the
1650 socket descriptor
for interfacing with virtfs
-proxy
-helper(1).
1653 Specifies the
default mode
for newly created files on the host
.
1654 Works only with security models
"mapped-xattr" and
1658 Specifies the
default mode
for newly created directories on the
1659 host
. Works only with security models
"mapped-xattr" and
1662 ``mount_tag
=mount_tag``
1663 Specifies the tag name to be used by the guest to mount
this
1666 ``multidevs
=multidevs``
1667 Specifies how to deal with multiple devices being shared with a
1668 9p export
. Supported behaviours are either
"remap", "forbid" or
1669 "warn". The latter is the
default behaviour on which virtfs
9p
1670 expects only one device to be shared with the same export
, and
1671 if more than one device is shared and accessed via the same
9p
1672 export then only a warning message is
logged (once
) by qemu on
1673 host side
. In order to avoid file ID collisions on guest you
1674 should either create a separate virtfs export
for each device to
1675 be shared with
guests (recommended way
) or you might use
"remap"
1676 instead which allows you to share multiple devices with only one
1677 export instead
, which is achieved by remapping the original
1678 inode numbers from host to guest
in a way that would prevent
1679 such collisions
. Remapping inodes
in such use cases is required
1680 because the original device IDs from host are
never passed and
1681 exposed on guest
. Instead all files of an export shared with
1682 virtfs always share the same device id on guest
. So two files
1683 with identical inode numbers but from actually different devices
1684 on host would otherwise cause a file ID collision and hence
1685 potential misbehaviours on guest
. "forbid" on the other hand
1686 assumes like
"warn" that only one device is shared by the same
1687 export
, however it will not only log a warning message but also
1688 deny access to additional devices on guest
. Note though that
1689 "forbid" does currently not block all possible file access
1690 operations (e
.g
. readdir() would still
return entries from other
1694 DEF("iscsi", HAS_ARG
, QEMU_OPTION_iscsi
,
1695 "-iscsi [user=user][,password=password]\n"
1696 " [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
1697 " [,initiator-name=initiator-iqn][,id=target-iqn]\n"
1698 " [,timeout=timeout]\n"
1699 " iSCSI session parameters\n", QEMU_ARCH_ALL
)
1703 Configure iSCSI session parameters
.
1708 DEFHEADING(USB convenience options
:)
1710 DEF("usb", 0, QEMU_OPTION_usb
,
1711 "-usb enable on-board USB host controller (if not enabled by default)\n",
1715 Enable USB emulation on machine types with an on
-board USB host
1716 controller (if not enabled by
default). Note that on
-board USB host
1717 controllers may not support USB
3.0. In
this case
1718 ``
-device qemu
-xhci`` can be used instead on machines with PCI
.
1721 DEF("usbdevice", HAS_ARG
, QEMU_OPTION_usbdevice
,
1722 "-usbdevice name add the host or guest USB device 'name'\n",
1725 ``
-usbdevice devname``
1726 Add the USB device devname
, and enable an on
-board USB controller
1727 if possible and
necessary (just like it can be done via
1728 ``
-machine usb
=on``
). Note that
this option is mainly intended
for
1729 the user
's convenience only. More fine-grained control can be
1730 achieved by selecting a USB host controller (if necessary) and the
1731 desired USB device via the ``-device`` option instead. For example,
1732 instead of using ``-usbdevice mouse`` it is possible to use
1733 ``-device qemu-xhci -device usb-mouse`` to connect the USB mouse
1734 to a USB 3.0 controller instead (at least on machines that support
1735 PCI and do not have an USB controller enabled by default yet).
1736 For more details, see the chapter about
1737 :ref:`Connecting USB devices` in the System Emulation Users Guide.
1738 Possible devices for devname are:
1741 Braille device. This will use BrlAPI to display the braille
1742 output on a real or fake device (i.e. it also creates a
1743 corresponding ``braille`` chardev automatically beside the
1744 ``usb-braille`` USB device).
1747 Smartcard reader device
1750 Standard USB keyboard. Will override the PS/2 keyboard (if present).
1753 Virtual Mouse. This will override the PS/2 mouse emulation when
1757 Pointer device that uses absolute coordinates (like a
1758 touchscreen). This means QEMU is able to report the mouse
1759 position without having to grab the mouse. Also overrides the
1760 PS/2 mouse emulation when activated.
1763 Wacom PenPartner USB tablet.
1770 DEFHEADING(Display options:)
1772 DEF("display", HAS_ARG, QEMU_OPTION_display,
1773 #if defined(CONFIG_SPICE)
1774 "-display spice-app[,gl=on|off]\n"
1776 #if defined(CONFIG_SDL)
1777 "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off]\n"
1778 " [,window_close=on|off][,gl=on|core|es|off]\n"
1780 #if defined(CONFIG_GTK)
1781 "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
1783 #if defined(CONFIG_VNC)
1784 "-display vnc=<display>[,<optargs>]\n"
1786 #if defined(CONFIG_CURSES)
1787 "-display curses[,charset=<encoding>]\n"
1789 #if defined(CONFIG_OPENGL)
1790 "-display egl-headless[,rendernode=<file>]\n"
1793 " select display backend type\n"
1794 " The default display is equivalent to\n "
1795 #if defined(CONFIG_GTK)
1796 "\"-display gtk\"\n"
1797 #elif defined(CONFIG_SDL)
1798 "\"-display sdl\"\n"
1799 #elif defined(CONFIG_COCOA)
1800 "\"-display cocoa\"\n"
1801 #elif defined(CONFIG_VNC)
1802 "\"-vnc localhost:0,to=99,id=default\"\n"
1804 "\"-display none\"\n"
1809 Select type of display to use. This option is a replacement for the
1810 old style -sdl/-curses/... options. Use ``-display help`` to list
1811 the available display types. Valid values for type are
1814 Display video output via SDL (usually in a separate graphics
1815 window; see the SDL documentation for other possibilities).
1818 Display video output via curses. For graphics device models
1819 which support a text mode, QEMU can display this output using a
1820 curses/ncurses interface. Nothing is displayed when the graphics
1821 device is in graphical mode or if the graphics device does not
1822 support a text mode. Generally only the VGA device models
1823 support text mode. The font charset used by the guest can be
1824 specified with the ``charset`` option, for example
1825 ``charset=CP850`` for IBM CP850 encoding. The default is
1829 Do not display video output. The guest will still see an
1830 emulated graphics card, but its output will not be displayed to
1831 the QEMU user. This option differs from the -nographic option in
1832 that it only affects what is done with video output; -nographic
1833 also changes the destination of the serial and parallel port
1837 Display video output in a GTK window. This interface provides
1838 drop-down menus and other UI elements to configure and control
1839 the VM during runtime.
1842 Start a VNC server on display <arg>
1845 Offload all OpenGL operations to a local DRI device. For any
1846 graphical display, this display needs to be paired with either
1847 VNC or SPICE displays.
1850 Start QEMU as a Spice server and launch the default Spice client
1851 application. The Spice server will redirect the serial consoles
1852 and QEMU monitors. (Since 4.0)
1855 DEF("nographic", 0, QEMU_OPTION_nographic,
1856 "-nographic disable graphical output and redirect serial I/Os to console\n",
1860 Normally, if QEMU is compiled with graphical window support, it
1861 displays output such as guest graphics, guest console, and the QEMU
1862 monitor in a window. With this option, you can totally disable
1863 graphical output so that QEMU is a simple command line application.
1864 The emulated serial port is redirected on the console and muxed with
1865 the monitor (unless redirected elsewhere explicitly). Therefore, you
1866 can still use QEMU to debug a Linux kernel with a serial console.
1867 Use C-a h for help on switching between the console and monitor.
1870 DEF("curses", 0, QEMU_OPTION_curses,
1871 "-curses shorthand for -display curses\n",
1875 Normally, if QEMU is compiled with graphical window support, it
1876 displays output such as guest graphics, guest console, and the QEMU
1877 monitor in a window. With this option, QEMU can display the VGA
1878 output when in text mode using a curses/ncurses interface. Nothing
1879 is displayed in graphical mode.
1882 DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
1883 "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
1887 Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
1888 this also affects the special keys (for fullscreen, monitor-mode
1892 DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
1893 "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
1897 Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
1898 also affects the special keys (for fullscreen, monitor-mode
1902 DEF("no-quit", 0, QEMU_OPTION_no_quit,
1903 "-no-quit disable SDL window close capability\n", QEMU_ARCH_ALL)
1906 Disable SDL window close capability.
1909 DEF("sdl", 0, QEMU_OPTION_sdl,
1910 "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL)
1916 DEF("spice", HAS_ARG, QEMU_OPTION_spice,
1917 "-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
1918 " [,x509-key-file=<file>][,x509-key-password=<file>]\n"
1919 " [,x509-cert-file=<file>][,x509-cacert-file=<file>]\n"
1920 " [,x509-dh-key-file=<file>][,addr=addr]\n"
1921 " [,ipv4=on|off][,ipv6=on|off][,unix=on|off]\n"
1922 " [,tls-ciphers=<list>]\n"
1923 " [,tls-channel=[main|display|cursor|inputs|record|playback]]\n"
1924 " [,plaintext-channel=[main|display|cursor|inputs|record|playback]]\n"
1925 " [,sasl=on|off][,disable-ticketing=on|off]\n"
1926 " [,password=<string>][,password-secret=<secret-id>]\n"
1927 " [,image-compression=[auto_glz|auto_lz|quic|glz|lz|off]]\n"
1928 " [,jpeg-wan-compression=[auto|never|always]]\n"
1929 " [,zlib-glz-wan-compression=[auto|never|always]]\n"
1930 " [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n"
1931 " [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n"
1932 " [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
1933 " [,gl=[on|off]][,rendernode=<file>]\n"
1935 " at least one of {port, tls-port} is mandatory\n",
1938 ``-spice option[,option[,...]]``
1939 Enable the spice remote desktop protocol. Valid options are
1942 Set the TCP port spice is listening on for plaintext channels.
1945 Set the IP address spice is listening on. Default is any
1948 ``ipv4=on|off``; \ ``ipv6=on|off``; \ ``unix=on|off``
1949 Force using the specified IP version.
1951 ``password=<string>``
1952 Set the password you need to authenticate.
1954 This option is deprecated and insecure because it leaves the
1955 password visible in the process listing. Use ``password-secret``
1958 ``password-secret=<secret-id>``
1959 Set the ID of the ``secret`` object containing the password
1960 you need to authenticate.
1963 Require that the client use SASL to authenticate with the spice.
1964 The exact choice of authentication method used is controlled
1965 from the system / user's SASL configuration file
for the
'qemu'
1966 service
. This is typically found
in /etc
/sasl2
/qemu
.conf
. If
1967 running QEMU as an unprivileged user
, an environment variable
1968 SASL\_CONF\_PATH can be used to make it search alternate
1969 locations
for the service config
. While some SASL auth methods
1970 can also provide data
encryption (eg GSSAPI
), it is recommended
1971 that SASL always be combined with the
'tls' and
'x509' settings
1972 to enable use of SSL and server certificates
. This ensures a
1973 data encryption preventing compromise of authentication
1976 ``disable
-ticketing
=on|off``
1977 Allow client connects without authentication
.
1979 ``disable
-copy
-paste
=on|off``
1980 Disable copy paste between the client and the guest
.
1982 ``disable
-agent
-file
-xfer
=on|off``
1983 Disable spice
-vdagent based file
-xfer between the client and the
1987 Set the TCP port spice is listening on
for encrypted channels
.
1990 Set the x509 file directory
. Expects same filenames as
-vnc
1993 ``x509
-key
-file
=<file
>``
; \ ``x509
-key
-password
=<file
>``
; \ ``x509
-cert
-file
=<file
>``
; \ ``x509
-cacert
-file
=<file
>``
; \ ``x509
-dh
-key
-file
=<file
>``
1994 The x509 file names can also be configured individually
.
1996 ``tls
-ciphers
=<list
>``
1997 Specify which ciphers to use
.
1999 ``tls
-channel
=[main|display|cursor|inputs|record|playback
]``
; \ ``plaintext
-channel
=[main|display|cursor|inputs|record|playback
]``
2000 Force specific channel to be used with or without TLS
2001 encryption
. The options can be specified multiple times to
2002 configure multiple channels
. The special name
"default" can be
2003 used to set the
default mode
. For channels which are not
2004 explicitly forced into one mode the spice client is allowed to
2005 pick tls
/plaintext as he pleases
.
2007 ``image
-compression
=[auto_glz|auto_lz|quic|glz|lz|off
]``
2008 Configure image
compression (lossless
). Default is auto\_glz
.
2010 ``jpeg
-wan
-compression
=[auto|
never|always
]``
; \ ``zlib
-glz
-wan
-compression
=[auto|
never|always
]``
2011 Configure wan image
compression (lossy
for slow links
). Default
2014 ``streaming
-video
=[off|all|filter
]``
2015 Configure video stream detection
. Default is off
.
2017 ``agent
-mouse
=[on|off
]``
2018 Enable
/disable passing mouse events via vdagent
. Default is on
.
2020 ``playback
-compression
=[on|off
]``
2021 Enable
/disable audio stream
compression (using celt
0.5.1).
2024 ``seamless
-migration
=[on|off
]``
2025 Enable
/disable spice seamless migration
. Default is off
.
2028 Enable
/disable OpenGL context
. Default is off
.
2030 ``rendernode
=<file
>``
2031 DRM render node
for OpenGL rendering
. If not specified
, it will
2032 pick the first available
. (Since
2.9)
2035 DEF("portrait", 0, QEMU_OPTION_portrait
,
2036 "-portrait rotate graphical output 90 deg left (only PXA LCD)\n",
2040 Rotate graphical output
90 deg
left (only PXA LCD
).
2043 DEF("rotate", HAS_ARG
, QEMU_OPTION_rotate
,
2044 "-rotate <deg> rotate graphical output some deg left (only PXA LCD)\n",
2048 Rotate graphical output some deg
left (only PXA LCD
).
2051 DEF("vga", HAS_ARG
, QEMU_OPTION_vga
,
2052 "-vga [std|cirrus|vmware|qxl|xenfb|tcx|cg3|virtio|none]\n"
2053 " select video card type\n", QEMU_ARCH_ALL
)
2056 Select type of VGA card to emulate
. Valid values
for type are
2059 Cirrus Logic GD5446 Video card
. All Windows versions starting
2060 from Windows
95 should recognize and use
this graphic card
. For
2061 optimal performances
, use
16 bit color depth
in the guest and
2062 the host OS
. (This card was the
default before QEMU
2.2)
2065 Standard VGA card with Bochs VBE extensions
. If your guest OS
2066 supports the VESA
2.0 VBE
extensions (e
.g
. Windows XP
) and
if
2067 you want to use high resolution
modes (>= 1280x1024x16
) then you
2068 should use
this option
. (This card is the
default since QEMU
2072 VMWare SVGA
-II compatible adapter
. Use it
if you have
2073 sufficiently recent XFree86
/XOrg server or Windows guest with a
2074 driver
for this card
.
2077 QXL paravirtual graphic card
. It is VGA
compatible (including
2078 VESA
2.0 VBE support
). Works best with qxl guest drivers
2079 installed though
. Recommended choice when
using the spice
2083 (sun4m only
) Sun TCX framebuffer
. This is the
default
2084 framebuffer
for sun4m machines and offers both
8-bit and
24-bit
2085 colour depths at a fixed resolution of
1024x768
.
2088 (sun4m only
) Sun cgthree framebuffer
. This is a simple
8-bit
2089 framebuffer
for sun4m machines available
in both
1024x768
2090 (OpenBIOS
) and
1152x900 (OBP
) resolutions aimed at people
2091 wishing to run older Solaris versions
.
2100 DEF("full-screen", 0, QEMU_OPTION_full_screen
,
2101 "-full-screen start in full screen\n", QEMU_ARCH_ALL
)
2104 Start
in full screen
.
2107 DEF("g", HAS_ARG
, QEMU_OPTION_g
,
2108 "-g WxH[xDEPTH] Set the initial graphical resolution and depth\n",
2109 QEMU_ARCH_PPC | QEMU_ARCH_SPARC | QEMU_ARCH_M68K
)
2111 ``
-g``
*width
*\ ``x``\
*height
*\ ``
[x``\
*depth
*\ ``
]``
2112 Set the initial graphical resolution and
depth (PPC
, SPARC only
).
2114 For PPC the
default is
800x600x32
.
2116 For SPARC with the TCX graphics device
, the
default is
1024x768x8
2117 with the option of
1024x768x24
. For cgthree
, the
default is
2118 1024x768x8 with the option of
1152x900x8
for people who wish to use
2122 DEF("vnc", HAS_ARG
, QEMU_OPTION_vnc
,
2123 "-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL
)
2125 ``
-vnc display
[,option
[,option
[,...]]]``
2126 Normally
, if QEMU is compiled with graphical window support
, it
2127 displays output such as guest graphics
, guest console
, and the QEMU
2128 monitor
in a window
. With
this option
, you can have QEMU listen on
2129 VNC display display and redirect the VGA display over the VNC
2130 session
. It is very useful to enable the usb tablet device when
2131 using this option (option ``
-device usb
-tablet``
). When
using the
2132 VNC display
, you must use the ``
-k`` parameter to set the keyboard
2133 layout
if you are not
using en
-us
. Valid syntax
for the display is
2136 With
this option
, QEMU will
try next available VNC displays
,
2137 until the number L
, if the origianlly defined
"-vnc display" is
2138 not available
, e
.g
. port
5900+display is already used by another
2139 application
. By
default, to
=0.
2142 TCP connections will only be allowed from host on display d
. By
2143 convention the TCP port is
5900+d
. Optionally
, host can be
2144 omitted
in which
case the server will accept connections from
2148 Connections will be allowed over UNIX domain sockets where path
2149 is the location of a unix socket to listen
for connections on
.
2152 VNC is initialized but not started
. The monitor ``change``
2153 command can be used to later start the VNC server
.
2155 Following the display value there may be one or more option flags
2156 separated by commas
. Valid options are
2159 Connect to a listening VNC client via a
"reverse" connection
.
2160 The client is specified by the display
. For reverse network
2161 connections (host
:d
,``reverse``
), the d argument is a TCP port
2162 number
, not a display number
.
2164 ``websocket
=on|off``
2165 Opens an additional TCP listening port dedicated to VNC
2166 Websocket connections
. If a bare websocket option is given
, the
2167 Websocket port is
5700+display
. An alternative port can be
2168 specified with the syntax ``websocket``\
=port
.
2170 If host is specified connections will only be allowed from
this
2171 host
. It is possible to control the websocket listen address
2172 independently
, using the syntax ``websocket``\
=host
:port
.
2174 If no TLS credentials are provided
, the websocket connection
2175 runs
in unencrypted mode
. If TLS credentials are provided
, the
2176 websocket connection requires encrypted client connections
.
2179 Require that password based authentication is used
for client
2182 The password must be set separately
using the ``set_password``
2183 command
in the
:ref
:`QEMU monitor`
. The
2184 syntax to change your password is
:
2185 ``set_password
<protocol
> <password
>`` where
<protocol
> could be
2186 either
"vnc" or
"spice".
2188 If you would like to change
<protocol
> password expiration
, you
2189 should use ``expire_password
<protocol
> <expiration
-time
>``
2190 where expiration time could be one of the following options
:
2191 now
, never, +seconds or UNIX time of expiration
, e
.g
. +60 to
2192 make password expire
in 60 seconds
, or
1335196800 to make
2193 password expire on
"Mon Apr 23 12:00:00 EDT 2012" (UNIX time
for
2194 this date and time
).
2196 You can also use keywords
"now" or
"never" for the expiration
2197 time to allow
<protocol
> password to expire immediately or
never
2200 ``password
-secret
=<secret
-id
>``
2201 Require that password based authentication is used
for client
2202 connections
, using the password provided by the ``secret``
2203 object identified by ``secret
-id``
.
2206 Provides the ID of a set of TLS credentials to use to secure the
2207 VNC server
. They will apply to both the normal VNC server socket
2208 and the websocket
socket (if enabled
). Setting TLS credentials
2209 will cause the VNC server socket to enable the VeNCrypt auth
2210 mechanism
. The credentials should have been previously created
2211 using the ``
-object tls
-creds`` argument
.
2214 Provides the ID of the QAuthZ authorization object against which
2215 the client
's x509 distinguished name will validated. This object
2216 is only resolved at time of use, so can be deleted and recreated
2217 on the fly while the VNC server is active. If missing, it will
2218 default to denying access.
2221 Require that the client use SASL to authenticate with the VNC
2222 server. The exact choice of authentication method used is
2223 controlled from the system / user's SASL configuration file
for
2224 the
'qemu' service
. This is typically found
in
2225 /etc
/sasl2
/qemu
.conf
. If running QEMU as an unprivileged user
,
2226 an environment variable SASL\_CONF\_PATH can be used to make it
2227 search alternate locations
for the service config
. While some
2228 SASL auth methods can also provide data
encryption (eg GSSAPI
),
2229 it is recommended that SASL always be combined with the
'tls'
2230 and
'x509' settings to enable use of SSL and server
2231 certificates
. This ensures a data encryption preventing
2232 compromise of authentication credentials
. See the
2233 :ref
:`VNC security` section
in the System Emulation Users Guide
2234 for details on
using SASL authentication
.
2237 Provides the ID of the QAuthZ authorization object against which
2238 the client
's SASL username will validated. This object is only
2239 resolved at time of use, so can be deleted and recreated on the
2240 fly while the VNC server is active. If missing, it will default
2244 Legacy method for enabling authorization of clients against the
2245 x509 distinguished name and SASL username. It results in the
2246 creation of two ``authz-list`` objects with IDs of
2247 ``vnc.username`` and ``vnc.x509dname``. The rules for these
2248 objects must be configured with the HMP ACL commands.
2250 This option is deprecated and should no longer be used. The new
2251 ``sasl-authz`` and ``tls-authz`` options are a replacement.
2254 Enable lossy compression methods (gradient, JPEG, ...). If this
2255 option is set, VNC client may receive lossy framebuffer updates
2256 depending on its encoding settings. Enabling this option can
2257 save a lot of bandwidth at the expense of quality.
2259 ``non-adaptive=on|off``
2260 Disable adaptive encodings. Adaptive encodings are enabled by
2261 default. An adaptive encoding will try to detect frequently
2262 updated screen regions, and send updates in these regions using
2263 a lossy encoding (like JPEG). This can be really helpful to save
2264 bandwidth when playing videos. Disabling adaptive encodings
2265 restores the original static behavior of encodings like Tight.
2267 ``share=[allow-exclusive|force-shared|ignore]``
2268 Set display sharing policy. 'allow
-exclusive
' allows clients to
2269 ask for exclusive access. As suggested by the rfb spec this is
2270 implemented by dropping other connections. Connecting multiple
2271 clients in parallel requires all clients asking for a shared
2272 session (vncviewer: -shared switch). This is the default.
2273 'force
-shared
' disables exclusive client access. Useful for
2274 shared desktop sessions, where you don't want someone forgetting
2275 specify
-shared disconnect everybody
else. 'ignore' completely
2276 ignores the shared flag and allows everybody connect
2277 unconditionally
. Doesn
't conform to the rfb spec but is
2278 traditional QEMU behavior.
2281 Set keyboard delay, for key down and key up events, in
2282 milliseconds. Default is 10. Keyboards are low-bandwidth
2283 devices, so this slowdown can help the device and guest to keep
2284 up and not lose events in case events are arriving in bulk.
2285 Possible causes for the latter are flaky network connections, or
2286 scripts for automated testing.
2288 ``audiodev=audiodev``
2289 Use the specified audiodev when the VNC client requests audio
2290 transmission. When not using an -audiodev argument, this option
2291 must be omitted, otherwise is must be present and specify a
2294 ``power-control=on|off``
2295 Permit the remote client to issue shutdown, reboot or reset power
2299 ARCHHEADING(, QEMU_ARCH_I386)
2301 ARCHHEADING(i386 target only:, QEMU_ARCH_I386)
2303 DEF("win2k-hack", 0, QEMU_OPTION_win2k_hack,
2304 "-win2k-hack use it when installing Windows 2000 to avoid a disk full bug\n",
2308 Use it when installing Windows 2000 to avoid a disk full bug. After
2309 Windows 2000 is installed, you no longer need this option (this
2310 option slows down the IDE transfers).
2313 DEF("no-fd-bootchk", 0, QEMU_OPTION_no_fd_bootchk,
2314 "-no-fd-bootchk disable boot signature checking for floppy disks\n",
2318 Disable boot signature checking for floppy disks in BIOS. May be
2319 needed to boot from old floppy disks.
2322 DEF("no-acpi", 0, QEMU_OPTION_no_acpi,
2323 "-no-acpi disable ACPI\n", QEMU_ARCH_I386 | QEMU_ARCH_ARM)
2326 Disable ACPI (Advanced Configuration and Power Interface) support.
2327 Use it if your guest OS complains about ACPI problems (PC target
2331 DEF("no-hpet", 0, QEMU_OPTION_no_hpet,
2332 "-no-hpet disable HPET\n", QEMU_ARCH_I386)
2335 Disable HPET support.
2338 DEF("acpitable", HAS_ARG, QEMU_OPTION_acpitable,
2339 "-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"
2340 " ACPI table description\n", QEMU_ARCH_I386)
2342 ``-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]...]``
2343 Add ACPI table with specified header fields and context from
2344 specified files. For file=, take whole ACPI table from the specified
2345 files, including all ACPI headers (possible overridden by other
2346 options). For data=, only data portion of the table is used, all
2347 header information is specified in the command line. If a SLIC table
2348 is supplied to QEMU, then the SLIC's oem\_id and oem\_table\_id
2349 fields will
override the same
in the RSDT and the
FADT (a
.k
.a
.
2350 FACP
), in order to ensure the field matches required by the
2351 Microsoft SLIC spec and the ACPI spec
.
2354 DEF("smbios", HAS_ARG
, QEMU_OPTION_smbios
,
2355 "-smbios file=binary\n"
2356 " load SMBIOS entry from binary file\n"
2357 "-smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d]\n"
2359 " specify SMBIOS type 0 fields\n"
2360 "-smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2361 " [,uuid=uuid][,sku=str][,family=str]\n"
2362 " specify SMBIOS type 1 fields\n"
2363 "-smbios type=2[,manufacturer=str][,product=str][,version=str][,serial=str]\n"
2364 " [,asset=str][,location=str]\n"
2365 " specify SMBIOS type 2 fields\n"
2366 "-smbios type=3[,manufacturer=str][,version=str][,serial=str][,asset=str]\n"
2368 " specify SMBIOS type 3 fields\n"
2369 "-smbios type=4[,sock_pfx=str][,manufacturer=str][,version=str][,serial=str]\n"
2370 " [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
2371 " specify SMBIOS type 4 fields\n"
2372 "-smbios type=11[,value=str][,path=filename]\n"
2373 " specify SMBIOS type 11 fields\n"
2374 "-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
2375 " [,asset=str][,part=str][,speed=%d]\n"
2376 " specify SMBIOS type 17 fields\n",
2377 QEMU_ARCH_I386 | QEMU_ARCH_ARM
)
2379 ``
-smbios file
=binary``
2380 Load SMBIOS entry from binary file
.
2382 ``
-smbios type
=0[,vendor
=str
][,version
=str
][,date
=str
][,release
=%d
.%d
][,uefi
=on|off
]``
2383 Specify SMBIOS type
0 fields
2385 ``
-smbios type
=1[,manufacturer
=str
][,product
=str
][,version
=str
][,serial
=str
][,uuid
=uuid
][,sku
=str
][,family
=str
]``
2386 Specify SMBIOS type
1 fields
2388 ``
-smbios type
=2[,manufacturer
=str
][,product
=str
][,version
=str
][,serial
=str
][,asset
=str
][,location
=str
]``
2389 Specify SMBIOS type
2 fields
2391 ``
-smbios type
=3[,manufacturer
=str
][,version
=str
][,serial
=str
][,asset
=str
][,sku
=str
]``
2392 Specify SMBIOS type
3 fields
2394 ``
-smbios type
=4[,sock_pfx
=str
][,manufacturer
=str
][,version
=str
][,serial
=str
][,asset
=str
][,part
=str
]``
2395 Specify SMBIOS type
4 fields
2397 ``
-smbios type
=11[,value
=str
][,path
=filename
]``
2398 Specify SMBIOS type
11 fields
2400 This argument can be repeated multiple times
, and values are added
in the order they are parsed
.
2401 Applications intending to use OEM strings data are encouraged to use their application name as
2402 a prefix
for the value string
. This facilitates passing information
for multiple applications
2405 The ``value
=str`` syntax provides the string data
inline, while the ``path
=filename`` syntax
2406 loads data from a file on disk
. Note that the file is not permitted to contain any NUL bytes
.
2408 Both the ``value`` and ``path`` options can be repeated multiple times and will be added to
2409 the SMBIOS table
in the order
in which they appear
.
2411 Note that on the x86 architecture
, the total size of all SMBIOS tables is limited to
65535
2412 bytes
. Thus the OEM strings data is not suitable
for passing large amounts of data into the
2413 guest
. Instead it should be used as a indicator to inform the guest where to locate the real
2414 data set
, for example
, by specifying the serial ID of a block device
.
2416 An example passing three strings is
2420 -smbios type
=11,value
=cloud
-init
:ds
=nocloud
-net
;s
=http
://10.10.0.1:8000/,\\
2421 value
=anaconda
:method
=http
://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os,\\
2422 path
=/some
/file
/with
/oemstringsdata
.txt
2424 In the guest OS
this is visible with the ``dmidecode`` command
2429 Handle
0x0E00, DMI type
11, 5 bytes
2431 String
1: cloud
-init
:ds
=nocloud
-net
;s
=http
://10.10.0.1:8000/
2432 String
2: anaconda
:method
=http
://dl.fedoraproject.org/pub/fedora/linux/releases/25/x86_64/os
2433 String
3: myapp
:some extra data
2436 ``
-smbios type
=17[,loc_pfx
=str
][,bank
=str
][,manufacturer
=str
][,serial
=str
][,asset
=str
][,part
=str
][,speed
=%d
]``
2437 Specify SMBIOS type
17 fields
2442 DEFHEADING(Network options
:)
2444 DEF("netdev", HAS_ARG
, QEMU_OPTION_netdev
,
2446 "-netdev user,id=str[,ipv4=on|off][,net=addr[/mask]][,host=addr]\n"
2447 " [,ipv6=on|off][,ipv6-net=addr[/int]][,ipv6-host=addr]\n"
2448 " [,restrict=on|off][,hostname=host][,dhcpstart=addr]\n"
2449 " [,dns=addr][,ipv6-dns=addr][,dnssearch=domain][,domainname=domain]\n"
2450 " [,tftp=dir][,tftp-server-name=name][,bootfile=f][,hostfwd=rule][,guestfwd=rule]"
2452 "[,smb=dir[,smbserver=addr]]\n"
2454 " configure a user mode network backend with ID 'str',\n"
2455 " its DHCP server and optional services\n"
2458 "-netdev tap,id=str,ifname=name\n"
2459 " configure a host TAP network backend with ID 'str'\n"
2461 "-netdev tap,id=str[,fd=h][,fds=x:y:...:z][,ifname=name][,script=file][,downscript=dfile]\n"
2462 " [,br=bridge][,helper=helper][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off]\n"
2463 " [,vhostfd=h][,vhostfds=x:y:...:z][,vhostforce=on|off][,queues=n]\n"
2465 " configure a host TAP network backend with ID 'str'\n"
2466 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE
")\n"
2467 " use network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT
")\n"
2468 " to configure it and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT
")\n"
2469 " to deconfigure it\n"
2470 " use '[down]script=no' to disable script execution\n"
2471 " use network helper 'helper' (default=" DEFAULT_BRIDGE_HELPER
") to\n"
2473 " use 'fd=h' to connect to an already opened TAP interface\n"
2474 " use 'fds=x:y:...:z' to connect to already opened multiqueue capable TAP interfaces\n"
2475 " use 'sndbuf=nbytes' to limit the size of the send buffer (the\n"
2476 " default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576')\n"
2477 " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n"
2478 " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n"
2479 " use vhost=on to enable experimental in kernel accelerator\n"
2480 " (only has effect for virtio guests which use MSIX)\n"
2481 " use vhostforce=on to force vhost on for non-MSIX virtio guests\n"
2482 " use 'vhostfd=h' to connect to an already opened vhost net device\n"
2483 " use 'vhostfds=x:y:...:z to connect to multiple already opened vhost net devices\n"
2484 " use 'queues=n' to specify the number of queues to be created for multiqueue TAP\n"
2485 " use 'poll-us=n' to specify the maximum number of microseconds that could be\n"
2486 " spent on busy polling for vhost net\n"
2487 "-netdev bridge,id=str[,br=bridge][,helper=helper]\n"
2488 " configure a host TAP network backend with ID 'str' that is\n"
2489 " connected to a bridge (default=" DEFAULT_BRIDGE_INTERFACE
")\n"
2490 " using the program 'helper (default=" DEFAULT_BRIDGE_HELPER
")\n"
2493 "-netdev l2tpv3,id=str,src=srcaddr,dst=dstaddr[,srcport=srcport][,dstport=dstport]\n"
2494 " [,rxsession=rxsession],txsession=txsession[,ipv6=on|off][,udp=on|off]\n"
2495 " [,cookie64=on|off][,counter][,pincounter][,txcookie=txcookie]\n"
2496 " [,rxcookie=rxcookie][,offset=offset]\n"
2497 " configure a network backend with ID 'str' connected to\n"
2498 " an Ethernet over L2TPv3 pseudowire.\n"
2499 " Linux kernel 3.3+ as well as most routers can talk\n"
2500 " L2TPv3. This transport allows connecting a VM to a VM,\n"
2501 " VM to a router and even VM to Host. It is a nearly-universal\n"
2502 " standard (RFC3931). Note - this implementation uses static\n"
2503 " pre-configured tunnels (same as the Linux kernel).\n"
2504 " use 'src=' to specify source address\n"
2505 " use 'dst=' to specify destination address\n"
2506 " use 'udp=on' to specify udp encapsulation\n"
2507 " use 'srcport=' to specify source udp port\n"
2508 " use 'dstport=' to specify destination udp port\n"
2509 " use 'ipv6=on' to force v6\n"
2510 " L2TPv3 uses cookies to prevent misconfiguration as\n"
2511 " well as a weak security measure\n"
2512 " use 'rxcookie=0x012345678' to specify a rxcookie\n"
2513 " use 'txcookie=0x012345678' to specify a txcookie\n"
2514 " use 'cookie64=on' to set cookie size to 64 bit, otherwise 32\n"
2515 " use 'counter=off' to force a 'cut-down' L2TPv3 with no counter\n"
2516 " use 'pincounter=on' to work around broken counter handling in peer\n"
2517 " use 'offset=X' to add an extra offset between header and data\n"
2519 "-netdev socket,id=str[,fd=h][,listen=[host]:port][,connect=host:port]\n"
2520 " configure a network backend to connect to another network\n"
2521 " using a socket connection\n"
2522 "-netdev socket,id=str[,fd=h][,mcast=maddr:port[,localaddr=addr]]\n"
2523 " configure a network backend to connect to a multicast maddr and port\n"
2524 " use 'localaddr=addr' to specify the host address to send packets from\n"
2525 "-netdev socket,id=str[,fd=h][,udp=host:port][,localaddr=host:port]\n"
2526 " configure a network backend to connect to another network\n"
2527 " using an UDP tunnel\n"
2529 "-netdev vde,id=str[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]\n"
2530 " configure a network backend to connect to port 'n' of a vde switch\n"
2531 " running on host and listening for incoming connections on 'socketpath'.\n"
2532 " Use group 'groupname' and mode 'octalmode' to change default\n"
2533 " ownership and permissions for communication port.\n"
2535 #ifdef CONFIG_NETMAP
2536 "-netdev netmap,id=str,ifname=name[,devname=nmname]\n"
2537 " attach to the existing netmap-enabled network interface 'name', or to a\n"
2538 " VALE port (created on the fly) called 'name' ('nmname' is name of the \n"
2539 " netmap device, defaults to '/dev/netmap')\n"
2542 "-netdev vhost-user,id=str,chardev=dev[,vhostforce=on|off]\n"
2543 " configure a vhost-user network, backed by a chardev 'dev'\n"
2546 "-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n"
2547 " configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n"
2549 "-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
2550 " configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL
)
2551 DEF("nic", HAS_ARG
, QEMU_OPTION_nic
,
2562 #ifdef CONFIG_NETMAP
2568 "socket][,option][,...][mac=macaddr]\n"
2569 " initialize an on-board / default host NIC (using MAC address\n"
2570 " macaddr) and connect it to the given host network backend\n"
2571 "-nic none use it alone to have zero network devices (the default is to\n"
2572 " provided a 'user' network connection)\n",
2574 DEF("net", HAS_ARG
, QEMU_OPTION_net
,
2575 "-net nic[,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v]\n"
2576 " configure or create an on-board (or machine default) NIC and\n"
2577 " connect it to hub 0 (please use -nic unless you need a hub)\n"
2587 #ifdef CONFIG_NETMAP
2590 "socket][,option][,option][,...]\n"
2591 " old way to initialize a host network interface\n"
2592 " (use the -netdev option if possible instead)\n", QEMU_ARCH_ALL
)
2594 ``
-nic
[tap|bridge|user|l2tpv3|vde|netmap|vhost
-user|socket
][,...][,mac
=macaddr
][,model
=mn
]``
2595 This option is a shortcut
for configuring both the on
-board
2596 (default) guest NIC hardware and the host network backend
in one go
.
2597 The host backend options are the same as with the corresponding
2598 ``
-netdev`` options below
. The guest NIC model can be set with
2599 ``model
=modelname``
. Use ``model
=help`` to list the available device
2600 types
. The hardware MAC address can be set with ``mac
=macaddr``
.
2602 The following two example
do exactly the same
, to show how ``
-nic``
2603 can be used to shorten the command line length
:
2607 |qemu_system|
-netdev user
,id
=n1
,ipv6
=off
-device e1000
,netdev
=n1
,mac
=52:54:98:76:54:32
2608 |qemu_system|
-nic user
,ipv6
=off
,model
=e1000
,mac
=52:54:98:76:54:32
2611 Indicate that no network devices should be configured
. It is used to
2612 override the
default configuration (default NIC with
"user" host
2613 network backend
) which is activated
if no other networking options
2616 ``
-netdev user
,id
=id
[,option
][,option
][,...]``
2617 Configure user mode host network backend which requires no
2618 administrator privilege to run
. Valid options are
:
2621 Assign symbolic name
for use
in monitor commands
.
2623 ``ipv4
=on|off and ipv6
=on|off``
2624 Specify that either IPv4 or IPv6 must be enabled
. If neither is
2625 specified both protocols are enabled
.
2628 Set IP network address the guest will see
. Optionally specify
2629 the netmask
, either
in the form a
.b
.c
.d or as number of valid
2630 top
-most bits
. Default is
10.0.2.0/24.
2633 Specify the guest
-visible address of the host
. Default is the
2634 2nd IP
in the guest network
, i
.e
. x
.x
.x
.2.
2636 ``ipv6
-net
=addr
[/int
]``
2637 Set IPv6 network address the guest will
see (default is
2638 fec0
::/64). The network prefix is given
in the usual hexadecimal
2639 IPv6 address notation
. The prefix size is optional
, and is given
2640 as the number of valid top
-most
bits (default is
64).
2643 Specify the guest
-visible IPv6 address of the host
. Default is
2644 the
2nd IPv6
in the guest network
, i
.e
. xxxx
::2.
2647 If
this option is enabled
, the guest will be isolated
, i
.e
. it
2648 will not be able to contact the host and no guest IP packets
2649 will be routed over the host to the outside
. This option does
2650 not affect any explicitly set forwarding rules
.
2653 Specifies the client hostname reported by the built
-in DHCP
2657 Specify the first of the
16 IPs the built
-in DHCP server can
2658 assign
. Default is the
15th to
31st IP
in the guest network
,
2659 i
.e
. x
.x
.x
.15 to x
.x
.x
.31.
2662 Specify the guest
-visible address of the virtual nameserver
. The
2663 address must be different from the host address
. Default is the
2664 3rd IP
in the guest network
, i
.e
. x
.x
.x
.3.
2667 Specify the guest
-visible address of the IPv6 virtual
2668 nameserver
. The address must be different from the host address
.
2669 Default is the
3rd IP
in the guest network
, i
.e
. xxxx
::3.
2671 ``dnssearch
=domain``
2672 Provides an entry
for the domain
-search list sent by the
2673 built
-in DHCP server
. More than one domain suffix can be
2674 transmitted by specifying
this option multiple times
. If
2675 supported
, this will cause the guest to automatically
try to
2676 append the given domain
suffix(es
) in case a domain name can not
2683 |qemu_system|
-nic user
,dnssearch
=mgmt
.example
.org
,dnssearch
=example
.org
2685 ``domainname
=domain``
2686 Specifies the client domain name reported by the built
-in DHCP
2690 When
using the user mode network stack
, activate a built
-in TFTP
2691 server
. The files
in dir will be exposed as the root of a TFTP
2692 server
. The TFTP client on the guest must be configured
in
2693 binary
mode (use the command ``bin`` of the Unix TFTP client
).
2695 ``tftp
-server
-name
=name``
2696 In BOOTP reply
, broadcast name as the
"TFTP server name"
2697 (RFC2132 option
66). This can be used to advise the guest to
2698 load boot files or configurations from a different server than
2702 When
using the user mode network stack
, broadcast file as the
2703 BOOTP filename
. In conjunction with ``tftp``
, this can be used
2704 to network boot a guest from a local directory
.
2706 Example (using pxelinux
):
2710 |qemu_system|
-hda linux
.img
-boot n
-device e1000
,netdev
=n1
\\
2711 -netdev user
,id
=n1
,tftp
=/path
/to
/tftp
/files
,bootfile
=/pxelinux
.0
2713 ``smb
=dir
[,smbserver
=addr
]``
2714 When
using the user mode network stack
, activate a built
-in SMB
2715 server so that Windows OSes can access to the host files
in
2716 ``dir`` transparently
. The IP address of the SMB server can be
2717 set to addr
. By
default the
4th IP
in the guest network is used
,
2720 In the guest Windows OS
, the line
:
2726 must be added
in the file ``C
:\WINDOWS\LMHOSTS``
(for windows
2727 9x
/Me
) or ``C
:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS``
(Windows
2730 Then ``dir`` can be accessed
in ``
\\smbserver\qemu``
.
2732 Note that a SAMBA server must be installed on the host OS
.
2734 ``hostfwd
=[tcp|udp
]:[hostaddr
]:hostport
-[guestaddr
]:guestport``
2735 Redirect incoming TCP or UDP connections to the host port
2736 hostport to the guest IP address guestaddr on guest port
2737 guestport
. If guestaddr is not specified
, its value is x
.x
.x
.15
2738 (default first address given by the built
-in DHCP server
). By
2739 specifying hostaddr
, the rule can be bound to a specific host
2740 interface. If no connection type is set
, TCP is used
. This
2741 option can be given multiple times
.
2743 For example
, to redirect host X11 connection from screen
1 to
2744 guest screen
0, use the following
:
2749 |qemu_system|
-nic user
,hostfwd
=tcp
:127.0.0.1:6001-:6000
2750 #
this host xterm should open
in the guest X11 server
2753 To redirect telnet connections from host port
5555 to telnet
2754 port on the guest
, use the following
:
2759 |qemu_system|
-nic user
,hostfwd
=tcp
::5555-:23
2760 telnet localhost
5555
2762 Then when you use on the host ``telnet localhost
5555``
, you
2763 connect to the guest telnet server
.
2765 ``guestfwd
=[tcp
]:server
:port
-dev``
; \ ``guestfwd
=[tcp
]:server
:port
-cmd
:command``
2766 Forward guest TCP connections to the IP address server on port
2767 port to the character device dev or to a program executed by
2768 cmd
:command which gets spawned
for each connection
. This option
2769 can be given multiple times
.
2771 You can either use a chardev directly and have that one used
2772 throughout QEMU
's lifetime, like in the following example:
2776 # open 10.10.1.1:4321 on bootup, connect 10.0.2.100:1234 to it whenever
2777 # the guest accesses it
2778 |qemu_system| -nic user,guestfwd=tcp:10.0.2.100:1234-tcp:10.10.1.1:4321
2780 Or you can execute a command on every TCP connection established
2781 by the guest, so that QEMU behaves similar to an inetd process
2782 for that virtual server:
2786 # call "netcat 10.10.1.1 4321" on every TCP connection to 10.0.2.100:1234
2787 # and connect the TCP stream to its stdin/stdout
2788 |qemu_system| -nic 'user
,id
=n1
,guestfwd
=tcp
:10.0.2.100:1234-cmd
:netcat
10.10.1.1 4321'
2790 ``-netdev tap,id=id[,fd=h][,ifname=name][,script=file][,downscript=dfile][,br=bridge][,helper=helper]``
2791 Configure a host TAP network backend with ID id.
2793 Use the network script file to configure it and the network script
2794 dfile to deconfigure it. If name is not provided, the OS
2795 automatically provides one. The default network configure script is
2796 ``/etc/qemu-ifup`` and the default network deconfigure script is
2797 ``/etc/qemu-ifdown``. Use ``script=no`` or ``downscript=no`` to
2798 disable script execution.
2800 If running QEMU as an unprivileged user, use the network helper
2801 to configure the TAP interface and attach it to the bridge.
2802 The default network helper executable is
2803 ``/path/to/qemu-bridge-helper`` and the default bridge device is
2806 ``fd``\ =h can be used to specify the handle of an already opened
2813 #launch a QEMU instance with the default network script
2814 |qemu_system| linux.img -nic tap
2818 #launch a QEMU instance with two NICs, each one connected
2820 |qemu_system| linux.img \\
2821 -netdev tap,id=nd0,ifname=tap0 -device e1000,netdev=nd0 \\
2822 -netdev tap,id=nd1,ifname=tap1 -device rtl8139,netdev=nd1
2826 #launch a QEMU instance with the default network helper to
2827 #connect a TAP device to bridge br0
2828 |qemu_system| linux.img -device virtio-net-pci,netdev=n1 \\
2829 -netdev tap,id=n1,"helper=/path/to/qemu-bridge-helper"
2831 ``-netdev bridge,id=id[,br=bridge][,helper=helper]``
2832 Connect a host TAP network interface to a host bridge device.
2834 Use the network helper helper to configure the TAP interface and
2835 attach it to the bridge. The default network helper executable is
2836 ``/path/to/qemu-bridge-helper`` and the default bridge device is
2843 #launch a QEMU instance with the default network helper to
2844 #connect a TAP device to bridge br0
2845 |qemu_system| linux.img -netdev bridge,id=n1 -device virtio-net,netdev=n1
2849 #launch a QEMU instance with the default network helper to
2850 #connect a TAP device to bridge qemubr0
2851 |qemu_system| linux.img -netdev bridge,br=qemubr0,id=n1 -device virtio-net,netdev=n1
2853 ``-netdev socket,id=id[,fd=h][,listen=[host]:port][,connect=host:port]``
2854 This host network backend can be used to connect the guest's network
2855 to another QEMU virtual machine
using a TCP socket connection
. If
2856 ``listen`` is specified
, QEMU waits
for incoming connections on port
2857 (host is optional
). ``connect`` is used to connect to another QEMU
2858 instance
using the ``listen`` option
. ``fd``\
=h specifies an
2859 already opened TCP socket
.
2865 # launch a first QEMU instance
2866 |qemu_system| linux
.img
\\
2867 -device e1000
,netdev
=n1
,mac
=52:54:00:12:34:56 \\
2868 -netdev socket
,id
=n1
,listen
=:1234
2869 # connect the network of
this instance to the network of the first instance
2870 |qemu_system| linux
.img
\\
2871 -device e1000
,netdev
=n2
,mac
=52:54:00:12:34:57 \\
2872 -netdev socket
,id
=n2
,connect
=127.0.0.1:1234
2874 ``
-netdev socket
,id
=id
[,fd
=h
][,mcast
=maddr
:port
[,localaddr
=addr
]]``
2875 Configure a socket host network backend to share the guest
's network
2876 traffic with another QEMU virtual machines using a UDP multicast
2877 socket, effectively making a bus for every QEMU with same multicast
2878 address maddr and port. NOTES:
2880 1. Several QEMU can be running on different hosts and share same bus
2881 (assuming correct multicast setup for these hosts).
2883 2. mcast support is compatible with User Mode Linux (argument
2884 ``ethN=mcast``), see http://user-mode-linux.sf.net.
2886 3. Use ``fd=h`` to specify an already opened UDP multicast socket.
2892 # launch one QEMU instance
2893 |qemu_system| linux.img \\
2894 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
2895 -netdev socket,id=n1,mcast=230.0.0.1:1234
2896 # launch another QEMU instance on same "bus"
2897 |qemu_system| linux.img \\
2898 -device e1000,netdev=n2,mac=52:54:00:12:34:57 \\
2899 -netdev socket,id=n2,mcast=230.0.0.1:1234
2900 # launch yet another QEMU instance on same "bus"
2901 |qemu_system| linux.img \\
2902 -device e1000,netdev=n3,mac=52:54:00:12:34:58 \\
2903 -netdev socket,id=n3,mcast=230.0.0.1:1234
2905 Example (User Mode Linux compat.):
2909 # launch QEMU instance (note mcast address selected is UML's
default)
2910 |qemu_system| linux
.img
\\
2911 -device e1000
,netdev
=n1
,mac
=52:54:00:12:34:56 \\
2912 -netdev socket
,id
=n1
,mcast
=239.192.168.1:1102
2914 /path
/to
/linux ubd0
=/path
/to
/root_fs eth0
=mcast
2916 Example (send packets from host
's 1.2.3.4):
2920 |qemu_system| linux.img \\
2921 -device e1000,netdev=n1,mac=52:54:00:12:34:56 \\
2922 -netdev socket,id=n1,mcast=239.192.168.1:1102,localaddr=1.2.3.4
2924 ``-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]``
2925 Configure a L2TPv3 pseudowire host network backend. L2TPv3 (RFC3931)
2926 is a popular protocol to transport Ethernet (and other Layer 2) data
2927 frames between two systems. It is present in routers, firewalls and
2928 the Linux kernel (from version 3.3 onwards).
2930 This transport allows a VM to communicate to another VM, router or
2934 source address (mandatory)
2937 destination address (mandatory)
2940 select udp encapsulation (default is ip).
2946 destination udp port.
2949 force v6, otherwise defaults to v4.
2951 ``rxcookie=rxcookie``; \ ``txcookie=txcookie``
2952 Cookies are a weak form of security in the l2tpv3 specification.
2953 Their function is mostly to prevent misconfiguration. By default
2957 Set cookie size to 64 bit instead of the default 32
2960 Force a 'cut
-down
' L2TPv3 with no counter as in
2961 draft-mkonstan-l2tpext-keyed-ipv6-tunnel-00
2964 Work around broken counter handling in peer. This may also help
2965 on networks which have packet reorder.
2968 Add an extra offset between header and data
2970 For example, to attach a VM running on host 4.3.2.1 via L2TPv3 to
2971 the bridge br-lan on the remote Linux host 1.2.3.4:
2975 # Setup tunnel on linux host using raw ip as encapsulation
2977 ip l2tp add tunnel remote 4.3.2.1 local 1.2.3.4 tunnel_id 1 peer_tunnel_id 1 \\
2978 encap udp udp_sport 16384 udp_dport 16384
2979 ip l2tp add session tunnel_id 1 name vmtunnel0 session_id \\
2980 0xFFFFFFFF peer_session_id 0xFFFFFFFF
2981 ifconfig vmtunnel0 mtu 1500
2982 ifconfig vmtunnel0 up
2983 brctl addif br-lan vmtunnel0
2987 # launch QEMU instance - if your network has reorder or is very lossy add ,pincounter
2989 |qemu_system| linux.img -device e1000,netdev=n1 \\
2990 -netdev l2tpv3,id=n1,src=4.2.3.1,dst=1.2.3.4,udp,srcport=16384,dstport=16384,rxsession=0xffffffff,txsession=0xffffffff,counter
2992 ``-netdev vde,id=id[,sock=socketpath][,port=n][,group=groupname][,mode=octalmode]``
2993 Configure VDE backend to connect to PORT n of a vde switch running
2994 on host and listening for incoming connections on socketpath. Use
2995 GROUP groupname and MODE octalmode to change default ownership and
2996 permissions for communication port. This option is only available if
2997 QEMU has been compiled with vde support enabled.
3004 vde_switch -F -sock /tmp/myswitch
3005 # launch QEMU instance
3006 |qemu_system| linux.img -nic vde,sock=/tmp/myswitch
3008 ``-netdev vhost-user,chardev=id[,vhostforce=on|off][,queues=n]``
3009 Establish a vhost-user netdev, backed by a chardev id. The chardev
3010 should be a unix domain socket backed one. The vhost-user uses a
3011 specifically defined protocol to pass vhost ioctl replacement
3012 messages to an application on the other end of the socket. On
3013 non-MSIX guests, the feature can be forced with vhostforce. Use
3014 'queues
=n
' to specify the number of queues to be created for
3015 multiqueue vhost-user.
3021 qemu -m 512 -object memory-backend-file,id=mem,size=512M,mem-path=/hugetlbfs,share=on \
3022 -numa node,memdev=mem \
3023 -chardev socket,id=chr0,path=/path/to/socket \
3024 -netdev type=vhost-user,id=net0,chardev=chr0 \
3025 -device virtio-net-pci,netdev=net0
3027 ``-netdev vhost-vdpa,vhostdev=/path/to/dev``
3028 Establish a vhost-vdpa netdev.
3030 vDPA device is a device that uses a datapath which complies with
3031 the virtio specifications with a vendor specific control path.
3032 vDPA devices can be both physically located on the hardware or
3033 emulated by software.
3035 ``-netdev hubport,id=id,hubid=hubid[,netdev=nd]``
3036 Create a hub port on the emulated hub with ID hubid.
3038 The hubport netdev lets you connect a NIC to a QEMU emulated hub
3039 instead of a single netdev. Alternatively, you can also connect the
3040 hubport to another netdev with ID nd by using the ``netdev=nd``
3043 ``-net nic[,netdev=nd][,macaddr=mac][,model=type] [,name=name][,addr=addr][,vectors=v]``
3044 Legacy option to configure or create an on-board (or machine
3045 default) Network Interface Card(NIC) and connect it either to the
3046 emulated hub with ID 0 (i.e. the default hub), or to the netdev nd.
3047 If model is omitted, then the default NIC model associated with the
3048 machine type is used. Note that the default NIC model may change in
3049 future QEMU releases, so it is highly recommended to always specify
3050 a model. Optionally, the MAC address can be changed to mac, the
3051 device address set to addr (PCI cards only), and a name can be
3052 assigned for use in monitor commands. Optionally, for PCI cards, you
3053 can specify the number v of MSI-X vectors that the card should have;
3054 this option currently only affects virtio cards; set v = 0 to
3055 disable MSI-X. If no ``-net`` option is specified, a single NIC is
3056 created. QEMU can emulate several different models of network card.
3057 Use ``-net nic,model=help`` for a list of available devices for your
3060 ``-net user|tap|bridge|socket|l2tpv3|vde[,...][,name=name]``
3061 Configure a host network backend (with the options corresponding to
3062 the same ``-netdev`` option) and connect it to the emulated hub 0
3063 (the default hub). Use name to specify the name of the hub port.
3068 DEFHEADING(Character device options:)
3070 DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
3072 "-chardev null,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3073 "-chardev socket,id=id[,host=host],port=port[,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off][,reconnect=seconds]\n"
3074 " [,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds][,mux=on|off]\n"
3075 " [,logfile=PATH][,logappend=on|off][,tls-creds=ID][,tls-authz=ID] (tcp)\n"
3076 "-chardev socket,id=id,path=path[,server=on|off][,wait=on|off][,telnet=on|off][,websocket=on|off][,reconnect=seconds]\n"
3077 " [,mux=on|off][,logfile=PATH][,logappend=on|off][,abstract=on|off][,tight=on|off] (unix)\n"
3078 "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
3079 " [,localport=localport][,ipv4=on|off][,ipv6=on|off][,mux=on|off]\n"
3080 " [,logfile=PATH][,logappend=on|off]\n"
3081 "-chardev msmouse,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3082 "-chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]]\n"
3083 " [,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3084 "-chardev ringbuf,id=id[,size=size][,logfile=PATH][,logappend=on|off]\n"
3085 "-chardev file,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3086 "-chardev pipe,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3088 "-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3089 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3091 "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3092 "-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
3094 #ifdef CONFIG_BRLAPI
3095 "-chardev braille,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3097 #if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
3098 || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
3099 "-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3100 "-chardev tty,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3102 #if defined(__linux__) || defined(__FreeBSD__) || defined(__DragonFly__)
3103 "-chardev parallel,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3104 "-chardev parport,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
3106 #if defined(CONFIG_SPICE)
3107 "-chardev spicevmc,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3108 "-chardev spiceport,id=id,name=name[,debug=debug][,logfile=PATH][,logappend=on|off]\n"
3114 The general form of a character device option is:
3116 ``-chardev backend,id=id[,mux=on|off][,options]``
3117 Backend is one of: ``null``, ``socket``, ``udp``, ``msmouse``,
3118 ``vc``, ``ringbuf``, ``file``, ``pipe``, ``console``, ``serial``,
3119 ``pty``, ``stdio``, ``braille``, ``tty``, ``parallel``, ``parport``,
3120 ``spicevmc``, ``spiceport``. The specific backend will determine the
3123 Use ``-chardev help`` to print all available chardev backend types.
3125 All devices must have an id, which can be any string up to 127
3126 characters long. It is used to uniquely identify this device in
3127 other command line directives.
3129 A character device may be used in multiplexing mode by multiple
3130 front-ends. Specify ``mux=on`` to enable this mode. A multiplexer is
3131 a "1:N" device, and here the "1" end is your specified chardev
3132 backend, and the "N" end is the various parts of QEMU that can talk
3133 to a chardev. If you create a chardev with ``id=myid`` and
3134 ``mux=on``, QEMU will create a multiplexer with your specified ID,
3135 and you can then configure multiple front ends to use that chardev
3136 ID for their input/output. Up to four different front ends can be
3137 connected to a single multiplexed chardev. (Without multiplexing
3138 enabled, a chardev can only be used by a single front end.) For
3139 instance you could use this to allow a single stdio chardev to be
3140 used by two serial ports and the QEMU monitor:
3144 -chardev stdio,mux=on,id=char0 \
3145 -mon chardev=char0,mode=readline \
3146 -serial chardev:char0 \
3147 -serial chardev:char0
3149 You can have more than one multiplexer in a system configuration;
3150 for instance you could have a TCP port multiplexed between UART 0
3151 and UART 1, and stdio multiplexed between the QEMU monitor and a
3156 -chardev stdio,mux=on,id=char0 \
3157 -mon chardev=char0,mode=readline \
3158 -parallel chardev:char0 \
3159 -chardev tcp,...,mux=on,id=char1 \
3160 -serial chardev:char1 \
3161 -serial chardev:char1
3163 When you're
using a multiplexed character device
, some escape
3164 sequences are interpreted
in the input
. See the chapter about
3165 :ref
:`keys
in the character backend multiplexer`
in the
3166 System Emulation Users Guide
for more details
.
3168 Note that some other command line options may implicitly create
3169 multiplexed character backends
; for instance ``
-serial mon
:stdio``
3170 creates a multiplexed stdio backend connected to the serial port and
3171 the QEMU monitor
, and ``
-nographic`` also multiplexes the console
3172 and the monitor to stdio
.
3174 There is currently no support
for multiplexing
in the other
3175 direction (where a single QEMU front end takes input and output from
3178 Every backend supports the ``logfile`` option
, which supplies the
3179 path to a file to record all data transmitted via the backend
. The
3180 ``logappend`` option controls whether the log file will be truncated
3181 or appended to when opened
.
3183 The available backends are
:
3185 ``
-chardev
null,id
=id``
3186 A void device
. This device will not emit any data
, and will drop any
3187 data it receives
. The
null backend does not take any options
.
3189 ``
-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
]``
3190 Create a two
-way stream socket
, which can be either a TCP or a unix
3191 socket
. A unix socket will be created
if ``path`` is specified
.
3192 Behaviour is undefined
if TCP options are specified
for a unix
3195 ``server
=on|off`` specifies that the socket shall be a listening socket
.
3197 ``wait
=on|off`` specifies that QEMU should not block waiting
for a client
3198 to connect to a listening socket
.
3200 ``telnet
=on|off`` specifies that traffic on the socket should interpret
3201 telnet escape sequences
.
3203 ``websocket
=on|off`` specifies that the socket uses WebSocket protocol
for
3206 ``reconnect`` sets the timeout
for reconnecting on non
-server
3207 sockets when the remote end goes away
. qemu will delay
this many
3208 seconds and then attempt to reconnect
. Zero disables reconnecting
,
3211 ``tls
-creds`` requests enablement of the TLS protocol
for
3212 encryption
, and specifies the id of the TLS credentials to use
for
3213 the handshake
. The credentials must be previously created with the
3214 ``
-object tls
-creds`` argument
.
3216 ``tls
-auth`` provides the ID of the QAuthZ authorization object
3217 against which the client
's x509 distinguished name will be
3218 validated. This object is only resolved at time of use, so can be
3219 deleted and recreated on the fly while the chardev server is active.
3220 If missing, it will default to denying access.
3222 TCP and unix socket options are given below:
3224 ``TCP options: port=port[,host=host][,to=to][,ipv4=on|off][,ipv6=on|off][,nodelay=on|off]``
3225 ``host`` for a listening socket specifies the local address to
3226 be bound. For a connecting socket species the remote host to
3227 connect to. ``host`` is optional for listening sockets. If not
3228 specified it defaults to ``0.0.0.0``.
3230 ``port`` for a listening socket specifies the local port to be
3231 bound. For a connecting socket specifies the port on the remote
3232 host to connect to. ``port`` can be given as either a port
3233 number or a service name. ``port`` is required.
3235 ``to`` is only relevant to listening sockets. If it is
3236 specified, and ``port`` cannot be bound, QEMU will attempt to
3237 bind to subsequent ports up to and including ``to`` until it
3238 succeeds. ``to`` must be specified as a port number.
3240 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4
3241 or IPv6 must be used. If neither is specified the socket may
3242 use either protocol.
3244 ``nodelay=on|off`` disables the Nagle algorithm.
3246 ``unix options: path=path[,abstract=on|off][,tight=on|off]``
3247 ``path`` specifies the local path of the unix socket. ``path``
3249 ``abstract=on|off`` specifies the use of the abstract socket namespace,
3250 rather than the filesystem. Optional, defaults to false.
3251 ``tight=on|off`` sets the socket length of abstract sockets to their minimum,
3252 rather than the full sun_path length. Optional, defaults to true.
3254 ``-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr][,localport=localport][,ipv4=on|off][,ipv6=on|off]``
3255 Sends all traffic from the guest to a remote host over UDP.
3257 ``host`` specifies the remote host to connect to. If not specified
3258 it defaults to ``localhost``.
3260 ``port`` specifies the port on the remote host to connect to.
3261 ``port`` is required.
3263 ``localaddr`` specifies the local address to bind to. If not
3264 specified it defaults to ``0.0.0.0``.
3266 ``localport`` specifies the local port to bind to. If not specified
3267 any available local port will be used.
3269 ``ipv4=on|off`` and ``ipv6=on|off`` specify that either IPv4 or IPv6 must be used.
3270 If neither is specified the device may use either protocol.
3272 ``-chardev msmouse,id=id``
3273 Forward QEMU's emulated msmouse events to the guest
. ``msmouse``
3274 does not take any options
.
3276 ``
-chardev vc
,id
=id
[[,width
=width
][,height
=height
]][[,cols
=cols
][,rows
=rows
]]``
3277 Connect to a QEMU text console
. ``vc`` may optionally be given a
3280 ``width`` and ``height`` specify the width and height respectively
3281 of the console
, in pixels
.
3283 ``cols`` and ``rows`` specify that the console be sized to fit a
3284 text console with the given dimensions
.
3286 ``
-chardev ringbuf
,id
=id
[,size
=size
]``
3287 Create a ring buffer with fixed size ``size``
. size must be a power
3288 of two and defaults to ``
64K``
.
3290 ``
-chardev file
,id
=id
,path
=path``
3291 Log all traffic received from the guest to a file
.
3293 ``path`` specifies the path of the file to be opened
. This file will
3294 be created
if it does not already exist
, and overwritten
if it does
.
3295 ``path`` is required
.
3297 ``
-chardev pipe
,id
=id
,path
=path``
3298 Create a two
-way connection to the guest
. The behaviour differs
3299 slightly between Windows hosts and other hosts
:
3301 On Windows
, a single duplex pipe will be created at
3304 On other hosts
, 2 pipes will be created called ``path
.in`` and
3305 ``path
.out``
. Data written to ``path
.in`` will be received by the
3306 guest
. Data written by the guest can be read from ``path
.out``
. QEMU
3307 will not create these fifos
, and requires them to be present
.
3309 ``path`` forms part of the pipe path as described above
. ``path`` is
3312 ``
-chardev console
,id
=id``
3313 Send traffic from the guest to QEMU
's standard output. ``console``
3314 does not take any options.
3316 ``console`` is only available on Windows hosts.
3318 ``-chardev serial,id=id,path=path``
3319 Send traffic from the guest to a serial device on the host.
3321 On Unix hosts serial will actually accept any tty device, not only
3324 ``path`` specifies the name of the serial device to open.
3326 ``-chardev pty,id=id``
3327 Create a new pseudo-terminal on the host and connect to it. ``pty``
3328 does not take any options.
3330 ``pty`` is not available on Windows hosts.
3332 ``-chardev stdio,id=id[,signal=on|off]``
3333 Connect to standard input and standard output of the QEMU process.
3335 ``signal`` controls if signals are enabled on the terminal, that
3336 includes exiting QEMU with the key sequence Control-c. This option
3337 is enabled by default, use ``signal=off`` to disable it.
3339 ``-chardev braille,id=id``
3340 Connect to a local BrlAPI server. ``braille`` does not take any
3343 ``-chardev tty,id=id,path=path``
3344 ``tty`` is only available on Linux, Sun, FreeBSD, NetBSD, OpenBSD
3345 and DragonFlyBSD hosts. It is an alias for ``serial``.
3347 ``path`` specifies the path to the tty. ``path`` is required.
3349 ``-chardev parallel,id=id,path=path``
3351 ``-chardev parport,id=id,path=path``
3352 ``parallel`` is only available on Linux, FreeBSD and DragonFlyBSD
3355 Connect to a local parallel port.
3357 ``path`` specifies the path to the parallel port device. ``path`` is
3360 ``-chardev spicevmc,id=id,debug=debug,name=name``
3361 ``spicevmc`` is only available when spice support is built in.
3363 ``debug`` debug level for spicevmc
3365 ``name`` name of spice channel to connect to
3367 Connect to a spice virtual machine channel, such as vdiport.
3369 ``-chardev spiceport,id=id,debug=debug,name=name``
3370 ``spiceport`` is only available when spice support is built in.
3372 ``debug`` debug level for spicevmc
3374 ``name`` name of spice port to connect to
3376 Connect to a spice port, allowing a Spice client to handle the
3377 traffic identified by a name (preferably a fqdn).
3383 DEFHEADING(TPM device options:)
3385 DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
3386 "-tpmdev passthrough,id=id[,path=path][,cancel-path=path]\n"
3387 " use path to provide path to a character device; default is /dev/tpm0\n"
3388 " use cancel-path to provide path to TPM's cancel sysfs entry
; if\n"
3389 " not provided it will be searched
for in /sys
/class/misc
/tpm?
/device
\n"
3390 "-tpmdev emulator
,id
=id
,chardev
=dev
\n"
3391 " configure the TPM device
using chardev backend
\n",
3394 The general form of a TPM device option is:
3396 ``-tpmdev backend,id=id[,options]``
3397 The specific backend type will determine the applicable options. The
3398 ``-tpmdev`` option creates the TPM backend and requires a
3399 ``-device`` option that specifies the TPM frontend interface model.
3401 Use ``-tpmdev help`` to print all available TPM backend types.
3403 The available backends are:
3405 ``-tpmdev passthrough,id=id,path=path,cancel-path=cancel-path``
3406 (Linux-host only) Enable access to the host's TPM using the
3409 ``path`` specifies the path to the host's TPM device, i.e., on a
3410 Linux host this would be ``/dev/tpm0``. ``path`` is optional and by
3411 default ``/dev/tpm0`` is used.
3413 ``cancel-path`` specifies the path to the host TPM device's sysfs
3414 entry allowing for cancellation of an ongoing TPM command.
3415 ``cancel-path`` is optional and by default QEMU will search for the
3418 Some notes about using the host's TPM with the passthrough driver:
3420 The TPM device accessed by the passthrough driver must not be used
3421 by any other application on the host.
3423 Since the host's firmware (BIOS/UEFI) has already initialized the
3424 TPM, the VM's firmware (BIOS/UEFI) will not be able to initialize
3425 the TPM again and may therefore not show a TPM-specific menu that
3426 would otherwise allow the user to configure the TPM, e.g., allow the
3427 user to enable/disable or activate/deactivate the TPM. Further, if
3428 TPM ownership is released from within a VM then the host's TPM will
3429 get disabled and deactivated. To enable and activate the TPM again
3430 afterwards, the host has to be rebooted and the user is required to
3431 enter the firmware's menu to enable and activate the TPM. If the TPM
3432 is left disabled and/or deactivated most TPM commands will fail.
3434 To create a passthrough TPM use the following two options:
3438 -tpmdev passthrough,id=tpm0 -device tpm-tis,tpmdev=tpm0
3440 Note that the ``-tpmdev`` id is ``tpm0`` and is referenced by
3441 ``tpmdev=tpm0`` in the device option.
3443 ``-tpmdev emulator,id=id,chardev=dev``
3444 (Linux-host only) Enable access to a TPM emulator using Unix domain
3445 socket based chardev backend.
3447 ``chardev`` specifies the unique ID of a character device backend
3448 that provides connection to the software TPM server.
3450 To create a TPM emulator backend device with chardev socket backend:
3454 -chardev socket,id=chrtpm,path=/tmp/swtpm-sock -tpmdev emulator,id=tpm0,chardev=chrtpm -device tpm-tis,tpmdev=tpm0
3461 DEFHEADING(Linux/Multiboot boot specific:)
3463 When using these options, you can use a given Linux or Multiboot kernel
3464 without installing it in the disk image. It can be useful for easier
3465 testing of various kernels.
3470 DEF("kernel
", HAS_ARG, QEMU_OPTION_kernel, \
3471 "-kernel bzImage use
'bzImage' as kernel image
\n", QEMU_ARCH_ALL)
3474 Use bzImage as kernel image. The kernel can be either a Linux kernel
3475 or in multiboot format.
3478 DEF("append
", HAS_ARG, QEMU_OPTION_append, \
3479 "-append cmdline use
'cmdline' as kernel command line
\n", QEMU_ARCH_ALL)
3482 Use cmdline as kernel command line
3485 DEF("initrd
", HAS_ARG, QEMU_OPTION_initrd, \
3486 "-initrd file use
'file' as initial ram disk
\n", QEMU_ARCH_ALL)
3489 Use file as initial ram disk.
3491 ``-initrd "file1 arg
=foo
,file2
"``
3492 This syntax is only available with multiboot.
3494 Use file1 and file2 as modules and pass arg=foo as parameter to the
3498 DEF("dtb
", HAS_ARG, QEMU_OPTION_dtb, \
3499 "-dtb file use
'file' as device tree image
\n", QEMU_ARCH_ALL)
3502 Use file as a device tree binary (dtb) image and pass it to the
3508 DEFHEADING(Debug/Expert options:)
3510 DEF("compat
", HAS_ARG, QEMU_OPTION_compat,
3511 "-compat
[deprecated
-input
=accept|reject
][,deprecated
-output
=accept|hide
]\n"
3512 " Policy
for handling deprecated management interfaces
\n",
3515 ``-compat [deprecated-input=@var{input-policy}][,deprecated-output=@var{output-policy}]``
3516 Set policy for handling deprecated management interfaces (experimental):
3518 ``deprecated-input=accept`` (default)
3519 Accept deprecated commands and arguments
3520 ``deprecated-input=reject``
3521 Reject deprecated commands and arguments
3522 ``deprecated-output=accept`` (default)
3523 Emit deprecated command results and events
3524 ``deprecated-output=hide``
3525 Suppress deprecated command results and events
3527 Limitation: covers only syntactic aspects of QMP.
3530 DEF("fw_cfg
", HAS_ARG, QEMU_OPTION_fwcfg,
3531 "-fw_cfg
[name
=]<name
>,file
=<file
>\n"
3532 " add named fw_cfg entry with contents from file
\n"
3533 "-fw_cfg
[name
=]<name
>,string
=<str
>\n"
3534 " add named fw_cfg entry with contents from string
\n",
3537 ``-fw_cfg [name=]name,file=file``
3538 Add named fw\_cfg entry with contents from file file.
3540 ``-fw_cfg [name=]name,string=str``
3541 Add named fw\_cfg entry with contents from string str.
3543 The terminating NUL character of the contents of str will not be
3544 included as part of the fw\_cfg item data. To insert contents with
3545 embedded NUL characters, you have to use the file parameter.
3547 The fw\_cfg entries are passed by QEMU through to the guest.
3553 -fw_cfg name=opt/com.mycompany/blob,file=./my_blob.bin
3555 creates an fw\_cfg entry named opt/com.mycompany/blob with contents
3556 from ./my\_blob.bin.
3559 DEF("serial
", HAS_ARG, QEMU_OPTION_serial, \
3560 "-serial dev redirect the serial port to char device
'dev'\n",
3564 Redirect the virtual serial port to host character device dev. The
3565 default device is ``vc`` in graphical mode and ``stdio`` in non
3568 This option can be used several times to simulate up to 4 serial
3571 Use ``-serial none`` to disable all serial ports.
3573 Available character devices are:
3576 Virtual console. Optionally, a width and height can be given in
3583 It is also possible to specify width or height in characters:
3590 [Linux only] Pseudo TTY (a new PTY is automatically allocated)
3593 No device is allocated.
3599 Use a named character device defined with the ``-chardev``
3603 [Linux only] Use host tty, e.g. ``/dev/ttyS0``. The host serial
3604 port parameters are set according to the emulated ones.
3607 [Linux only, parallel port only] Use host parallel port N.
3608 Currently SPP and EPP parallel port features can be used.
3611 Write output to filename. No character can be read.
3614 [Unix only] standard input/output
3620 [Windows only] Use host serial port n
3622 ``udp:[remote_host]:remote_port[@[src_ip]:src_port]``
3623 This implements UDP Net Console. When remote\_host or src\_ip
3624 are not specified they default to ``0.0.0.0``. When not using a
3625 specified src\_port a random port is automatically chosen.
3627 If you just want a simple readonly console you can use
3628 ``netcat`` or ``nc``, by starting QEMU with:
3629 ``-serial udp::4555`` and nc as: ``nc -u -l -p 4555``. Any time
3630 QEMU writes something to that port it will appear in the
3633 If you plan to send characters back via netconsole or you want
3634 to stop and start QEMU a lot of times, you should have QEMU use
3635 the same source port each time by using something like ``-serial
3636 udp::4555@:4556`` to QEMU. Another approach is to use a patched
3637 version of netcat which can listen to a TCP port and send and
3638 receive characters via udp. If you have a patched version of
3639 netcat which activates telnet remote echo and single char
3640 transfer, then you can use the following options to set up a
3641 netcat redirector to allow telnet on port 5555 to access the
3645 -serial udp::4555@:4556
3648 -u -P 4555 -L 0.0.0.0:4556 -t -p 5555 -I -T
3653 ``tcp:[host]:port[,server=on|off][,wait=on|off][,nodelay=on|off][,reconnect=seconds]``
3654 The TCP Net Console has two modes of operation. It can send the
3655 serial I/O to a location or wait for a connection from a
3656 location. By default the TCP Net Console is sent to host at the
3657 port. If you use the ``server=on`` option QEMU will wait for a client
3658 socket application to connect to the port before continuing,
3659 unless the ``wait=on|off`` option was specified. The ``nodelay=on|off``
3660 option disables the Nagle buffering algorithm. The ``reconnect=on``
3661 option only applies if ``server=no`` is set, if the connection goes
3662 down it will attempt to reconnect at the given interval. If host
3663 is omitted, 0.0.0.0 is assumed. Only one TCP connection at a
3664 time is accepted. You can use ``telnet=on`` to connect to the
3665 corresponding character device.
3667 ``Example to send tcp console to 192.168.0.2 port 4444``
3668 -serial tcp:192.168.0.2:4444
3670 ``Example to listen and wait on port 4444 for connection``
3671 -serial tcp::4444,server=on
3673 ``Example to not wait and listen on ip 192.168.0.100 port 4444``
3674 -serial tcp:192.168.0.100:4444,server=on,wait=off
3676 ``telnet:host:port[,server=on|off][,wait=on|off][,nodelay=on|off]``
3677 The telnet protocol is used instead of raw tcp sockets. The
3678 options work the same as if you had specified ``-serial tcp``.
3679 The difference is that the port acts like a telnet server or
3680 client using telnet option negotiation. This will also allow you
3681 to send the MAGIC\_SYSRQ sequence if you use a telnet that
3682 supports sending the break sequence. Typically in unix telnet
3683 you do it with Control-] and then type "send
break" followed by
3684 pressing the enter key.
3686 ``websocket:host:port,server=on[,wait=on|off][,nodelay=on|off]``
3687 The WebSocket protocol is used instead of raw tcp socket. The
3688 port acts as a WebSocket server. Client mode is not supported.
3690 ``unix:path[,server=on|off][,wait=on|off][,reconnect=seconds]``
3691 A unix domain socket is used instead of a tcp socket. The option
3692 works the same as if you had specified ``-serial tcp`` except
3693 the unix domain socket path is used for connections.
3696 This is a special option to allow the monitor to be multiplexed
3697 onto another serial port. The monitor is accessed with key
3698 sequence of Control-a and then pressing c. dev\_string should be
3699 any one of the serial devices specified above. An example to
3700 multiplex the monitor onto a telnet server listening on port
3703 ``-serial mon:telnet::4444,server=on,wait=off``
3705 When the monitor is multiplexed to stdio in this way, Ctrl+C
3706 will not terminate QEMU any more but will be passed to the guest
3710 Braille device. This will use BrlAPI to display the braille
3711 output on a real or fake device.
3714 Three button serial mouse. Configure the guest to use Microsoft
3718 DEF("parallel
", HAS_ARG, QEMU_OPTION_parallel, \
3719 "-parallel dev redirect the parallel port to char device
'dev'\n",
3723 Redirect the virtual parallel port to host device dev (same devices
3724 as the serial port). On Linux hosts, ``/dev/parportN`` can be used
3725 to use hardware devices connected on the corresponding host parallel
3728 This option can be used several times to simulate up to 3 parallel
3731 Use ``-parallel none`` to disable all parallel ports.
3734 DEF("monitor
", HAS_ARG, QEMU_OPTION_monitor, \
3735 "-monitor dev redirect the monitor to char device
'dev'\n",
3739 Redirect the monitor to host device dev (same devices as the serial
3740 port). The default device is ``vc`` in graphical mode and ``stdio``
3741 in non graphical mode. Use ``-monitor none`` to disable the default
3744 DEF("qmp
", HAS_ARG, QEMU_OPTION_qmp, \
3745 "-qmp dev like
-monitor but opens
in 'control' mode
\n",
3749 Like -monitor but opens in 'control' mode.
3751 DEF("qmp
-pretty
", HAS_ARG, QEMU_OPTION_qmp_pretty, \
3752 "-qmp
-pretty dev like
-qmp but uses pretty JSON formatting
\n",
3756 Like -qmp but uses pretty JSON formatting.
3759 DEF("mon
", HAS_ARG, QEMU_OPTION_mon, \
3760 "-mon
[chardev
=]name
[,mode
=readline|control
][,pretty
[=on|off
]]\n", QEMU_ARCH_ALL)
3762 ``-mon [chardev=]name[,mode=readline|control][,pretty[=on|off]]``
3763 Setup monitor on chardev name. ``pretty`` is only valid when
3764 ``mode=control``, turning on JSON pretty printing to ease
3765 human reading and debugging.
3768 DEF("debugcon
", HAS_ARG, QEMU_OPTION_debugcon, \
3769 "-debugcon dev redirect the debug console to char device
'dev'\n",
3773 Redirect the debug console to host device dev (same devices as the
3774 serial port). The debug console is an I/O port which is typically
3775 port 0xe9; writing to that I/O port sends output to this device. The
3776 default device is ``vc`` in graphical mode and ``stdio`` in non
3780 DEF("pidfile
", HAS_ARG, QEMU_OPTION_pidfile, \
3781 "-pidfile file write PID to
'file'\n", QEMU_ARCH_ALL)
3784 Store the QEMU process PID in file. It is useful if you launch QEMU
3788 DEF("singlestep
", 0, QEMU_OPTION_singlestep, \
3789 "-singlestep always run
in singlestep mode
\n", QEMU_ARCH_ALL)
3792 Run the emulation in single step mode.
3795 DEF("preconfig
", 0, QEMU_OPTION_preconfig, \
3796 "--preconfig pause QEMU before machine is
initialized (experimental
)\n",
3800 Pause QEMU for interactive configuration before the machine is
3801 created, which allows querying and configuring properties that will
3802 affect machine initialization. Use QMP command 'x-exit-preconfig' to
3803 exit the preconfig state and move to the next state (i.e. run guest
3804 if -S isn't used or pause the second time if -S is used). This
3805 option is experimental.
3808 DEF("S
", 0, QEMU_OPTION_S, \
3809 "-S freeze CPU at
startup (use
'c' to start execution
)\n",
3813 Do not start CPU at startup (you must type 'c' in the monitor).
3816 DEF("overcommit
", HAS_ARG, QEMU_OPTION_overcommit,
3817 "-overcommit
[mem
-lock
=on|off
][cpu
-pm
=on|off
]\n"
3818 " run qemu with overcommit hints
\n"
3819 " mem
-lock
=on|off controls memory lock
support (default: off
)\n"
3820 " cpu
-pm
=on|off controls cpu power
management (default: off
)\n",
3823 ``-overcommit mem-lock=on|off``
3825 ``-overcommit cpu-pm=on|off``
3826 Run qemu with hints about host resource overcommit. The default is
3827 to assume that host overcommits all resources.
3829 Locking qemu and guest memory can be enabled via ``mem-lock=on``
3830 (disabled by default). This works when host memory is not
3831 overcommitted and reduces the worst-case latency for guest.
3833 Guest ability to manage power state of host cpus (increasing latency
3834 for other processes on the same host cpu, but decreasing latency for
3835 guest) can be enabled via ``cpu-pm=on`` (disabled by default). This
3836 works best when host CPU is not overcommitted. When used, host
3837 estimates of CPU cycle and power utilization will be incorrect, not
3838 taking into account guest idle time.
3841 DEF("gdb
", HAS_ARG, QEMU_OPTION_gdb, \
3842 "-gdb dev accept gdb connection on
'dev'. (QEMU defaults to starting
\n"
3843 " the guest without waiting
for gdb to connect
; use
-S too
\n"
3844 " if you want it to not start execution
.)\n",
3848 Accept a gdb connection on device dev (see the :ref:`GDB usage` chapter
3849 in the System Emulation Users Guide). Note that this option does not pause QEMU
3850 execution -- if you want QEMU to not start the guest until you
3851 connect with gdb and issue a ``continue`` command, you will need to
3852 also pass the ``-S`` option to QEMU.
3854 The most usual configuration is to listen on a local TCP socket::
3858 but you can specify other backends; UDP, pseudo TTY, or even stdio
3859 are all reasonable use cases. For example, a stdio connection
3860 allows you to start QEMU from within gdb and establish the
3861 connection via a pipe:
3865 (gdb) target remote | exec |qemu_system| -gdb stdio ...
3868 DEF("s
", 0, QEMU_OPTION_s, \
3869 "-s shorthand
for -gdb tcp
::" DEFAULT_GDBSTUB_PORT "\n",
3873 Shorthand for -gdb tcp::1234, i.e. open a gdbserver on TCP port 1234
3874 (see the :ref:`GDB usage` chapter in the System Emulation Users Guide).
3877 DEF("d
", HAS_ARG, QEMU_OPTION_d, \
3878 "-d item1
,... enable logging of specified
items (use
'-d help' for a list of log items
)\n",
3882 Enable logging of specified items. Use '-d help' for a list of log
3886 DEF("D
", HAS_ARG, QEMU_OPTION_D, \
3887 "-D logfile output log to
logfile (default stderr
)\n",
3891 Output log in logfile instead of to stderr
3894 DEF("dfilter
", HAS_ARG, QEMU_OPTION_DFILTER, \
3895 "-dfilter range
,.. filter debug output to range of
addresses (useful
for -d cpu
,exec
,etc
..)\n",
3898 ``-dfilter range1[,...]``
3899 Filter debug output to that relevant to a range of target addresses.
3900 The filter spec can be either start+size, start-size or start..end
3901 where start end and size are the addresses and sizes required. For
3906 -dfilter 0x8000..0x8fff,0xffffffc000080000+0x200,0xffffffc000060000-0x1000
3908 Will dump output for any code in the 0x1000 sized block starting at
3909 0x8000 and the 0x200 sized block starting at 0xffffffc000080000 and
3910 another 0x1000 sized block starting at 0xffffffc00005f000.
3913 DEF("seed
", HAS_ARG, QEMU_OPTION_seed, \
3914 "-seed number seed the pseudo
-random number generator
\n",
3918 Force the guest to use a deterministic pseudo-random number
3919 generator, seeded with number. This does not affect crypto routines
3923 DEF("L
", HAS_ARG, QEMU_OPTION_L, \
3924 "-L path set the directory
for the BIOS
, VGA BIOS and keymaps
\n",
3928 Set the directory for the BIOS, VGA BIOS and keymaps.
3930 To list all the data directories, use ``-L help``.
3933 DEF("bios
", HAS_ARG, QEMU_OPTION_bios, \
3934 "-bios file set the filename
for the BIOS
\n", QEMU_ARCH_ALL)
3937 Set the filename for the BIOS.
3940 DEF("enable
-kvm
", 0, QEMU_OPTION_enable_kvm, \
3941 "-enable
-kvm enable KVM full virtualization support
\n", QEMU_ARCH_ALL)
3944 Enable KVM full virtualization support. This option is only
3945 available if KVM support is enabled when compiling.
3948 DEF("xen
-domid
", HAS_ARG, QEMU_OPTION_xen_domid,
3949 "-xen
-domid id specify xen guest domain id
\n", QEMU_ARCH_ALL)
3950 DEF("xen
-attach
", 0, QEMU_OPTION_xen_attach,
3951 "-xen
-attach attach to existing xen domain
\n"
3952 " libxl will use
this when starting QEMU
\n",
3954 DEF("xen
-domid
-restrict
", 0, QEMU_OPTION_xen_domid_restrict,
3955 "-xen
-domid
-restrict restrict set of available xen operations
\n"
3956 " to specified domain id
. (Does not affect
\n"
3957 " xenpv machine type
).\n",
3961 Specify xen guest domain id (XEN only).
3964 Attach to existing xen domain. libxl will use this when starting
3965 QEMU (XEN only). Restrict set of available xen operations to
3966 specified domain id (XEN only).
3969 DEF("no
-reboot
", 0, QEMU_OPTION_no_reboot, \
3970 "-no
-reboot exit instead of rebooting
\n", QEMU_ARCH_ALL)
3973 Exit instead of rebooting.
3976 DEF("no
-shutdown
", 0, QEMU_OPTION_no_shutdown, \
3977 "-no
-shutdown stop before shutdown
\n", QEMU_ARCH_ALL)
3980 Don't exit QEMU on guest shutdown, but instead only stop the
3981 emulation. This allows for instance switching to monitor to commit
3982 changes to the disk image.
3985 DEF("action
", HAS_ARG, QEMU_OPTION_action,
3986 "-action reboot
=reset|shutdown
\n"
3987 " action when guest reboots
[default=reset
]\n"
3988 "-action shutdown
=poweroff|pause
\n"
3989 " action when guest shuts down
[default=poweroff
]\n"
3990 "-action panic
=pause|shutdown|none
\n"
3991 " action when guest panics
[default=shutdown
]\n"
3992 "-action watchdog
=reset|shutdown|poweroff|inject
-nmi|pause|debug|none
\n"
3993 " action when watchdog fires
[default=reset
]\n",
3996 ``-action event=action``
3997 The action parameter serves to modify QEMU's default behavior when
3998 certain guest events occur. It provides a generic method for specifying the
3999 same behaviors that are modified by the ``-no-reboot`` and ``-no-shutdown``
4004 ``-action panic=none``
4005 ``-action reboot=shutdown,shutdown=pause``
4006 ``-watchdog i6300esb -action watchdog=pause``
4010 DEF("loadvm
", HAS_ARG, QEMU_OPTION_loadvm, \
4011 "-loadvm
[tag|id
]\n" \
4012 " start right away with a saved
state (loadvm
in monitor
)\n",
4016 Start right away with a saved state (``loadvm`` in monitor)
4020 DEF("daemonize
", 0, QEMU_OPTION_daemonize, \
4021 "-daemonize daemonize QEMU after initializing
\n", QEMU_ARCH_ALL)
4025 Daemonize the QEMU process after initialization. QEMU will not
4026 detach from standard IO until it is ready to receive connections on
4027 any of its devices. This option is a useful way for external
4028 programs to launch QEMU without having to cope with initialization
4032 DEF("option
-rom
", HAS_ARG, QEMU_OPTION_option_rom, \
4033 "-option
-rom rom load a file
, rom
, into the option ROM space
\n",
4036 ``-option-rom file``
4037 Load the contents of file as an option ROM. This option is useful to
4038 load things like EtherBoot.
4041 DEF("rtc
", HAS_ARG, QEMU_OPTION_rtc, \
4042 "-rtc
[base
=utc|localtime|
<datetime
>][,clock
=host|rt|vm
][,driftfix
=none|slew
]\n" \
4043 " set the RTC base and clock
, enable drift fix
for clock
ticks (x86 only
)\n",
4047 ``-rtc [base=utc|localtime|datetime][,clock=host|rt|vm][,driftfix=none|slew]``
4048 Specify ``base`` as ``utc`` or ``localtime`` to let the RTC start at
4049 the current UTC or local time, respectively. ``localtime`` is
4050 required for correct date in MS-DOS or Windows. To start at a
4051 specific point in time, provide datetime in the format
4052 ``2006-06-17T16:01:21`` or ``2006-06-17``. The default base is UTC.
4054 By default the RTC is driven by the host system time. This allows
4055 using of the RTC as accurate reference clock inside the guest,
4056 specifically if the host time is smoothly following an accurate
4057 external reference clock, e.g. via NTP. If you want to isolate the
4058 guest time from the host, you can set ``clock`` to ``rt`` instead,
4059 which provides a host monotonic clock if host support it. To even
4060 prevent the RTC from progressing during suspension, you can set
4061 ``clock`` to ``vm`` (virtual clock). '\ ``clock=vm``\ ' is
4062 recommended especially in icount mode in order to preserve
4063 determinism; however, note that in icount mode the speed of the
4064 virtual clock is variable and can in general differ from the host
4067 Enable ``driftfix`` (i386 targets only) if you experience time drift
4068 problems, specifically with Windows' ACPI HAL. This option will try
4069 to figure out how many timer interrupts were not processed by the
4070 Windows guest and will re-inject them.
4073 DEF("icount
", HAS_ARG, QEMU_OPTION_icount, \
4074 "-icount
[shift
=N|auto
][,align
=on|off
][,sleep
=on|off
][,rr
=record|replay
,rrfile
=<filename
>[,rrsnapshot
=<snapshot
>]]\n" \
4075 " enable virtual instruction counter with
2^N clock ticks per
\n" \
4076 " instruction
, enable aligning the host and virtual clocks
\n" \
4077 " or disable real time cpu sleeping
, and optionally enable
\n" \
4078 " record
-and
-replay mode
\n", QEMU_ARCH_ALL)
4080 ``-icount [shift=N|auto][,align=on|off][,sleep=on|off][,rr=record|replay,rrfile=filename[,rrsnapshot=snapshot]]``
4081 Enable virtual instruction counter. The virtual cpu will execute one
4082 instruction every 2^N ns of virtual time. If ``auto`` is specified
4083 then the virtual cpu speed will be automatically adjusted to keep
4084 virtual time within a few seconds of real time.
4086 Note that while this option can give deterministic behavior, it does
4087 not provide cycle accurate emulation. Modern CPUs contain
4088 superscalar out of order cores with complex cache hierarchies. The
4089 number of instructions executed often has little or no correlation
4090 with actual performance.
4092 When the virtual cpu is sleeping, the virtual time will advance at
4093 default speed unless ``sleep=on`` is specified. With
4094 ``sleep=on``, the virtual time will jump to the next timer
4095 deadline instantly whenever the virtual cpu goes to sleep mode and
4096 will not advance if no timer is enabled. This behavior gives
4097 deterministic execution times from the guest point of view.
4098 The default if icount is enabled is ``sleep=off``.
4099 ``sleep=on`` cannot be used together with either ``shift=auto``
4102 ``align=on`` will activate the delay algorithm which will try to
4103 synchronise the host clock and the virtual clock. The goal is to
4104 have a guest running at the real frequency imposed by the shift
4105 option. Whenever the guest clock is behind the host clock and if
4106 ``align=on`` is specified then we print a message to the user to
4107 inform about the delay. Currently this option does not work when
4108 ``shift`` is ``auto``. Note: The sync algorithm will work for those
4109 shift values for which the guest clock runs ahead of the host clock.
4110 Typically this happens when the shift value is high (how high
4111 depends on the host machine). The default if icount is enabled
4114 When the ``rr`` option is specified deterministic record/replay is
4115 enabled. The ``rrfile=`` option must also be provided to
4116 specify the path to the replay log. In record mode data is written
4117 to this file, and in replay mode it is read back.
4118 If the ``rrsnapshot`` option is given then it specifies a VM snapshot
4119 name. In record mode, a new VM snapshot with the given name is created
4120 at the start of execution recording. In replay mode this option
4121 specifies the snapshot name used to load the initial VM state.
4124 DEF("watchdog
", HAS_ARG, QEMU_OPTION_watchdog, \
4125 "-watchdog model
\n" \
4126 " enable virtual hardware watchdog
[default=none
]\n",
4130 Create a virtual hardware watchdog device. Once enabled (by a guest
4131 action), the watchdog must be periodically polled by an agent inside
4132 the guest or else the guest will be restarted. Choose a model for
4133 which your guest has drivers.
4135 The model is the model of hardware watchdog to emulate. Use
4136 ``-watchdog help`` to list available hardware models. Only one
4137 watchdog can be enabled for a guest.
4139 The following models may be available:
4142 iBASE 700 is a very simple ISA watchdog with a single timer.
4145 Intel 6300ESB I/O controller hub is a much more featureful
4146 PCI-based dual-timer watchdog.
4149 A virtual watchdog for s390x backed by the diagnose 288
4150 hypercall (currently KVM only).
4153 DEF("watchdog
-action
", HAS_ARG, QEMU_OPTION_watchdog_action, \
4154 "-watchdog
-action reset|shutdown|poweroff|inject
-nmi|pause|debug|none
\n" \
4155 " action when watchdog fires
[default=reset
]\n",
4158 ``-watchdog-action action``
4159 The action controls what QEMU will do when the watchdog timer
4160 expires. The default is ``reset`` (forcefully reset the guest).
4161 Other possible actions are: ``shutdown`` (attempt to gracefully
4162 shutdown the guest), ``poweroff`` (forcefully poweroff the guest),
4163 ``inject-nmi`` (inject a NMI into the guest), ``pause`` (pause the
4164 guest), ``debug`` (print a debug message and continue), or ``none``
4167 Note that the ``shutdown`` action requires that the guest responds
4168 to ACPI signals, which it may not be able to do in the sort of
4169 situations where the watchdog would have expired, and thus
4170 ``-watchdog-action shutdown`` is not recommended for production use.
4174 ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700``
4178 DEF("echr
", HAS_ARG, QEMU_OPTION_echr, \
4179 "-echr chr set terminal escape character instead of ctrl
-a
\n",
4182 ``-echr numeric_ascii_value``
4183 Change the escape character used for switching to the monitor when
4184 using monitor and serial sharing. The default is ``0x01`` when using
4185 the ``-nographic`` option. ``0x01`` is equal to pressing
4186 ``Control-a``. You can select a different character from the ascii
4187 control keys where 1 through 26 map to Control-a through Control-z.
4188 For instance you could use the either of the following to change the
4189 escape character to Control-t.
4191 ``-echr 0x14``; \ ``-echr 20``
4195 DEF("incoming
", HAS_ARG, QEMU_OPTION_incoming, \
4196 "-incoming tcp
:[host
]:port
[,to
=maxport
][,ipv4
=on|off
][,ipv6
=on|off
]\n" \
4197 "-incoming rdma
:host
:port
[,ipv4
=on|off
][,ipv6
=on|off
]\n" \
4198 "-incoming unix
:socketpath
\n" \
4199 " prepare
for incoming migration
, listen on
\n" \
4200 " specified protocol and socket address
\n" \
4201 "-incoming fd
:fd
\n" \
4202 "-incoming exec
:cmdline
\n" \
4203 " accept incoming migration on given file descriptor
\n" \
4204 " or from given external command
\n" \
4205 "-incoming defer
\n" \
4206 " wait
for the URI to be specified via migrate_incoming
\n",
4209 ``-incoming tcp:[host]:port[,to=maxport][,ipv4=on|off][,ipv6=on|off]``
4211 ``-incoming rdma:host:port[,ipv4=on|off][,ipv6=on|off]``
4212 Prepare for incoming migration, listen on a given tcp port.
4214 ``-incoming unix:socketpath``
4215 Prepare for incoming migration, listen on a given unix socket.
4218 Accept incoming migration from a given filedescriptor.
4220 ``-incoming exec:cmdline``
4221 Accept incoming migration as an output from specified external
4225 Wait for the URI to be specified via migrate\_incoming. The monitor
4226 can be used to change settings (such as migration parameters) prior
4227 to issuing the migrate\_incoming to allow the migration to begin.
4230 DEF("only
-migratable
", 0, QEMU_OPTION_only_migratable, \
4231 "-only
-migratable allow only migratable devices
\n", QEMU_ARCH_ALL)
4233 ``-only-migratable``
4234 Only allow migratable devices. Devices will not be allowed to enter
4235 an unmigratable state.
4238 DEF("nodefaults
", 0, QEMU_OPTION_nodefaults, \
4239 "-nodefaults don
't create default devices\n", QEMU_ARCH_ALL)
4242 Don't create
default devices
. Normally
, QEMU sets the
default
4243 devices like serial port
, parallel port
, virtual console
, monitor
4244 device
, VGA adapter
, floppy and CD
-ROM drive and others
. The
4245 ``
-nodefaults`` option will disable all those
default devices
.
4249 DEF("chroot", HAS_ARG
, QEMU_OPTION_chroot
, \
4250 "-chroot dir chroot to dir just before starting the VM\n",
4255 Immediately before starting guest execution
, chroot to the specified
4256 directory
. Especially useful
in combination with
-runas
.
4260 DEF("runas", HAS_ARG
, QEMU_OPTION_runas
, \
4261 "-runas user change to user id user just before starting the VM\n" \
4262 " user can be numeric uid:gid instead\n",
4267 Immediately before starting guest execution
, drop root privileges
,
4268 switching to the specified user
.
4271 DEF("prom-env", HAS_ARG
, QEMU_OPTION_prom_env
,
4272 "-prom-env variable=value\n"
4273 " set OpenBIOS nvram variables\n",
4274 QEMU_ARCH_PPC | QEMU_ARCH_SPARC
)
4276 ``
-prom
-env variable
=value``
4277 Set OpenBIOS nvram variable to given
value (PPC
, SPARC only
).
4281 qemu
-system
-sparc
-prom
-env
'auto-boot?=false' \
4282 -prom
-env
'boot-device=sd(0,2,0):d' -prom
-env
'boot-args=linux single'
4286 qemu
-system
-ppc
-prom
-env
'auto-boot?=false' \
4287 -prom
-env
'boot-device=hd:2,\yaboot' \
4288 -prom
-env
'boot-args=conf=hd:2,\yaboot.conf'
4290 DEF("semihosting", 0, QEMU_OPTION_semihosting
,
4291 "-semihosting semihosting mode\n",
4292 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4293 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV
)
4296 Enable semihosting
mode (ARM
, M68K
, Xtensa
, MIPS
, Nios II
, RISC
-V only
).
4298 Note that
this allows guest direct access to the host filesystem
, so
4299 should only be used with a trusted guest OS
.
4301 See the
-semihosting
-config option documentation
for further
4302 information about the facilities
this enables
.
4304 DEF("semihosting-config", HAS_ARG
, QEMU_OPTION_semihosting_config
,
4305 "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
4306 " semihosting configuration\n",
4307 QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA | QEMU_ARCH_LM32 |
4308 QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV
)
4310 ``
-semihosting
-config
[enable
=on|off
][,target
=native|gdb|auto
][,chardev
=id
][,arg
=str
[,...]]``
4311 Enable and configure
semihosting (ARM
, M68K
, Xtensa
, MIPS
, Nios II
, RISC
-V
4314 Note that
this allows guest direct access to the host filesystem
, so
4315 should only be used with a trusted guest OS
.
4317 On Arm
this implements the standard semihosting API
, version
2.0.
4319 On M68K
this implements the
"ColdFire GDB" interface used by
4322 Xtensa semihosting provides basic file IO calls
, such as
4323 open
/read
/write
/seek
/select
. Tensilica baremetal libc
for ISS and
4324 linux platform
"sim" use
this interface.
4326 On RISC
-V
this implements the standard semihosting API
, version
0.2.
4328 ``target
=native|gdb|auto``
4329 Defines where the semihosting calls will be addressed
, to QEMU
4330 (``native``
) or to
GDB (``gdb``
). The
default is ``auto``
, which
4331 means ``gdb`` during debug sessions and ``native`` otherwise
.
4334 Send the output to a chardev backend output
for native or auto
4335 output when not
in gdb
4337 ``arg
=str1
,arg
=str2
,...``
4338 Allows the user to pass input arguments
, and can be used
4339 multiple times to build up a list
. The old
-style
4340 ``
-kernel``
/``
-append`` method of passing a command line is
4341 still supported
for backward compatibility
. If both the
4342 ``
--semihosting
-config arg`` and the ``
-kernel``
/``
-append`` are
4343 specified
, the former is passed to semihosting as it always
4346 DEF("old-param", 0, QEMU_OPTION_old_param
,
4347 "-old-param old param mode\n", QEMU_ARCH_ARM
)
4350 Old param
mode (ARM only
).
4353 DEF("sandbox", HAS_ARG
, QEMU_OPTION_sandbox
, \
4354 "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
4355 " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
4356 " Enable seccomp mode 2 system call filter (default 'off').\n" \
4357 " use 'obsolete' to allow obsolete system calls that are provided\n" \
4358 " by the kernel, but typically no longer used by modern\n" \
4359 " C library implementations.\n" \
4360 " use 'elevateprivileges' to allow or deny the QEMU process ability\n" \
4361 " to elevate privileges using set*uid|gid system calls.\n" \
4362 " The value 'children' will deny set*uid|gid system calls for\n" \
4363 " main QEMU process but will allow forks and execves to run unprivileged\n" \
4364 " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
4365 " blocking *fork and execve\n" \
4366 " use 'resourcecontrol' to disable process affinity and schedular priority\n",
4369 ``
-sandbox arg
[,obsolete
=string
][,elevateprivileges
=string
][,spawn
=string
][,resourcecontrol
=string
]``
4370 Enable Seccomp mode
2 system call filter
. 'on' will enable syscall
4371 filtering and
'off' will disable it
. The
default is
'off'.
4374 Enable Obsolete system calls
4376 ``elevateprivileges
=string``
4377 Disable set\
*uid\|gid system calls
4380 Disable \
*fork and execve
4382 ``resourcecontrol
=string``
4383 Disable process affinity and schedular priority
4386 DEF("readconfig", HAS_ARG
, QEMU_OPTION_readconfig
,
4387 "-readconfig <file>\n", QEMU_ARCH_ALL
)
4389 ``
-readconfig file``
4390 Read device configuration from file
. This approach is useful when
4391 you want to spawn QEMU process with many command line options but
4392 you don
't want to exceed the command line character limit.
4394 DEF("writeconfig", HAS_ARG, QEMU_OPTION_writeconfig,
4395 "-writeconfig <file>\n"
4396 " read/write config file (deprecated)\n", QEMU_ARCH_ALL)
4400 DEF("no-user-config", 0, QEMU_OPTION_nouserconfig,
4402 " do not load default user-provided config files at startup\n",
4406 The ``-no-user-config`` option makes QEMU not load any of the
4407 user-provided config files on sysconfdir.
4410 DEF("trace", HAS_ARG, QEMU_OPTION_trace,
4411 "-trace [[enable=]<pattern>][,events=<file>][,file=<file>]\n"
4412 " specify tracing options\n",
4415 ``-trace [[enable=]pattern][,events=file][,file=file]``
4416 .. include:: ../qemu-option-trace.rst.inc
4419 DEF("plugin", HAS_ARG, QEMU_OPTION_plugin,
4420 "-plugin [file=]<file>[,arg=<string>]\n"
4424 ``-plugin file=file[,arg=string]``
4428 Load the given plugin from a shared library file.
4431 Argument string passed to the plugin. (Can be given multiple
4436 DEF("qtest", HAS_ARG, QEMU_OPTION_qtest, "", QEMU_ARCH_ALL)
4437 DEF("qtest-log", HAS_ARG, QEMU_OPTION_qtest_log, "", QEMU_ARCH_ALL)
4440 DEF("enable-fips", 0, QEMU_OPTION_enablefips,
4441 "-enable-fips enable FIPS 140-2 compliance\n",
4446 Enable FIPS 140-2 compliance mode.
4449 DEF("msg", HAS_ARG, QEMU_OPTION_msg,
4450 "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
4451 " control error message format\n"
4452 " timestamp=on enables timestamps (default: off)\n"
4453 " guest-name=on enables guest name prefix but only if\n"
4454 " -name guest option is set (default: off)\n",
4457 ``-msg [timestamp[=on|off]][,guest-name[=on|off]]``
4458 Control error message format.
4460 ``timestamp=on|off``
4461 Prefix messages with a timestamp. Default is off.
4463 ``guest-name=on|off``
4464 Prefix messages with guest name but only if -name guest option is set
4465 otherwise the option is ignored. Default is off.
4468 DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
4469 "-dump-vmstate <file>\n"
4470 " Output vmstate information in JSON format to file.\n"
4471 " Use the scripts/vmstate-static-checker.py file to\n"
4472 " check for possible regressions in migration code\n"
4473 " by comparing two such vmstate dumps.\n",
4476 ``-dump-vmstate file``
4477 Dump json-encoded vmstate information for current machine type to
4481 DEF("enable-sync-profile", 0, QEMU_OPTION_enable_sync_profile,
4482 "-enable-sync-profile\n"
4483 " enable synchronization profiling\n",
4486 ``-enable-sync-profile``
4487 Enable synchronization profiling.
4492 DEFHEADING(Generic object creation:)
4494 DEF("object", HAS_ARG, QEMU_OPTION_object,
4495 "-object TYPENAME[,PROP1=VALUE1,...]\n"
4496 " create a new object of type TYPENAME setting properties\n"
4497 " in the order they are specified. Note that the 'id
'\n"
4498 " property must be set. These objects are placed in the\n"
4499 " '/objects
' path.\n",
4502 ``-object typename[,prop1=value1,...]``
4503 Create a new object of type typename setting properties in the order
4504 they are specified. Note that the 'id
' property must be set. These
4505 objects are placed in the '/objects
' path.
4507 ``-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``
4508 Creates a memory file backend object, which can be used to back
4509 the guest RAM with huge pages.
4511 The ``id`` parameter is a unique ID that will be used to
4512 reference this memory region when configuring the ``-numa``
4515 The ``size`` option provides the size of the memory region, and
4516 accepts common suffixes, eg ``500M``.
4518 The ``mem-path`` provides the path to either a shared memory or
4519 huge page filesystem mount.
4521 The ``share`` boolean option determines whether the memory
4522 region is marked as private to QEMU, or shared. The latter
4523 allows a co-operating external process to access the QEMU memory
4526 The ``share`` is also required for pvrdma devices due to
4527 limitations in the RDMA API provided by Linux.
4529 Setting share=on might affect the ability to configure NUMA
4530 bindings for the memory backend under some circumstances, see
4531 Documentation/vm/numa\_memory\_policy.txt on the Linux kernel
4532 source tree for additional details.
4534 Setting the ``discard-data`` boolean option to on indicates that
4535 file contents can be destroyed when QEMU exits, to avoid
4536 unnecessarily flushing data to the backing file. Note that
4537 ``discard-data`` is only an optimization, and QEMU might not
4538 discard file contents if it aborts unexpectedly or is terminated
4541 The ``merge`` boolean option enables memory merge, also known as
4542 MADV\_MERGEABLE, so that Kernel Samepage Merging will consider
4543 the pages for memory deduplication.
4545 Setting the ``dump`` boolean option to off excludes the memory
4546 from core dumps. This feature is also known as MADV\_DONTDUMP.
4548 The ``prealloc`` boolean option enables memory preallocation.
4550 The ``host-nodes`` option binds the memory range to a list of
4553 The ``policy`` option sets the NUMA policy to one of the
4560 prefer the given host node list for allocation
4563 restrict memory allocation to the given host node list
4566 interleave memory allocations across the given host node
4569 The ``align`` option specifies the base address alignment when
4570 QEMU mmap(2) ``mem-path``, and accepts common suffixes, eg
4571 ``2M``. Some backend store specified by ``mem-path`` requires an
4572 alignment different than the default one used by QEMU, eg the
4573 device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In
4574 such cases, users can specify the required alignment via this
4577 The ``pmem`` option specifies whether the backing file specified
4578 by ``mem-path`` is in host persistent memory that can be
4579 accessed using the SNIA NVM programming model (e.g. Intel
4580 NVDIMM). If ``pmem`` is set to 'on
', QEMU will take necessary
4581 operations to guarantee the persistence of its own writes to
4582 ``mem-path`` (e.g. in vNVDIMM label emulation and live
4583 migration). Also, we will map the backend-file with MAP\_SYNC
4584 flag, which ensures the file metadata is in sync for
4585 ``mem-path`` in case of host crash or a power failure. MAP\_SYNC
4586 requires support from both the host kernel (since Linux kernel
4587 4.15) and the filesystem of ``mem-path`` mounted with DAX
4590 The ``readonly`` option specifies whether the backing file is opened
4591 read-only or read-write (default).
4593 ``-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``
4594 Creates a memory backend object, which can be used to back the
4595 guest RAM. Memory backend objects offer more control than the
4596 ``-m`` option that is traditionally used to define guest RAM.
4597 Please refer to ``memory-backend-file`` for a description of the
4600 ``-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``
4601 Creates an anonymous memory file backend object, which allows
4602 QEMU to share the memory with an external process (e.g. when
4603 using vhost-user). The memory is allocated with memfd and
4604 optional sealing. (Linux only)
4606 The ``seal`` option creates a sealed-file, that will block
4607 further resizing the memory ('on
' by default).
4609 The ``hugetlb`` option specify the file to be created resides in
4610 the hugetlbfs filesystem (since Linux 4.14). Used in conjunction
4611 with the ``hugetlb`` option, the ``hugetlbsize`` option specify
4612 the hugetlb page size on systems that support multiple hugetlb
4613 page sizes (it must be a power of 2 value supported by the
4616 In some versions of Linux, the ``hugetlb`` option is
4617 incompatible with the ``seal`` option (requires at least Linux
4620 Please refer to ``memory-backend-file`` for a description of the
4623 The ``share`` boolean option is on by default with memfd.
4625 ``-object rng-builtin,id=id``
4626 Creates a random number generator backend which obtains entropy
4627 from QEMU builtin functions. The ``id`` parameter is a unique ID
4628 that will be used to reference this entropy backend from the
4629 ``virtio-rng`` device. By default, the ``virtio-rng`` device
4630 uses this RNG backend.
4632 ``-object rng-random,id=id,filename=/dev/random``
4633 Creates a random number generator backend which obtains entropy
4634 from a device on the host. The ``id`` parameter is a unique ID
4635 that will be used to reference this entropy backend from the
4636 ``virtio-rng`` device. The ``filename`` parameter specifies
4637 which file to obtain entropy from and if omitted defaults to
4640 ``-object rng-egd,id=id,chardev=chardevid``
4641 Creates a random number generator backend which obtains entropy
4642 from an external daemon running on the host. The ``id``
4643 parameter is a unique ID that will be used to reference this
4644 entropy backend from the ``virtio-rng`` device. The ``chardev``
4645 parameter is the unique ID of a character device backend that
4646 provides the connection to the RNG daemon.
4648 ``-object tls-creds-anon,id=id,endpoint=endpoint,dir=/path/to/cred/dir,verify-peer=on|off``
4649 Creates a TLS anonymous credentials object, which can be used to
4650 provide TLS support on network backends. The ``id`` parameter is
4651 a unique ID which network backends will use to access the
4652 credentials. The ``endpoint`` is either ``server`` or ``client``
4653 depending on whether the QEMU network backend that uses the
4654 credentials will be acting as a client or as a server. If
4655 ``verify-peer`` is enabled (the default) then once the handshake
4656 is completed, the peer credentials will be verified, though this
4657 is a no-op for anonymous credentials.
4659 The dir parameter tells QEMU where to find the credential files.
4660 For server endpoints, this directory may contain a file
4661 dh-params.pem providing diffie-hellman parameters to use for the
4662 TLS server. If the file is missing, QEMU will generate a set of
4663 DH parameters at startup. This is a computationally expensive
4664 operation that consumes random pool entropy, so it is
4665 recommended that a persistent set of parameters be generated
4668 ``-object tls-creds-psk,id=id,endpoint=endpoint,dir=/path/to/keys/dir[,username=username]``
4669 Creates a TLS Pre-Shared Keys (PSK) credentials object, which
4670 can be used to provide TLS support on network backends. The
4671 ``id`` parameter is a unique ID which network backends will use
4672 to access the credentials. The ``endpoint`` is either ``server``
4673 or ``client`` depending on whether the QEMU network backend that
4674 uses the credentials will be acting as a client or as a server.
4675 For clients only, ``username`` is the username which will be
4676 sent to the server. If omitted it defaults to "qemu".
4678 The dir parameter tells QEMU where to find the keys file. It is
4679 called "dir/keys.psk" and contains "username:key" pairs. This
4680 file can most easily be created using the GnuTLS ``psktool``
4683 For server endpoints, dir may also contain a file dh-params.pem
4684 providing diffie-hellman parameters to use for the TLS server.
4685 If the file is missing, QEMU will generate a set of DH
4686 parameters at startup. This is a computationally expensive
4687 operation that consumes random pool entropy, so it is
4688 recommended that a persistent set of parameters be generated up
4691 ``-object tls-creds-x509,id=id,endpoint=endpoint,dir=/path/to/cred/dir,priority=priority,verify-peer=on|off,passwordid=id``
4692 Creates a TLS anonymous credentials object, which can be used to
4693 provide TLS support on network backends. The ``id`` parameter is
4694 a unique ID which network backends will use to access the
4695 credentials. The ``endpoint`` is either ``server`` or ``client``
4696 depending on whether the QEMU network backend that uses the
4697 credentials will be acting as a client or as a server. If
4698 ``verify-peer`` is enabled (the default) then once the handshake
4699 is completed, the peer credentials will be verified. With x509
4700 certificates, this implies that the clients must be provided
4701 with valid client certificates too.
4703 The dir parameter tells QEMU where to find the credential files.
4704 For server endpoints, this directory may contain a file
4705 dh-params.pem providing diffie-hellman parameters to use for the
4706 TLS server. If the file is missing, QEMU will generate a set of
4707 DH parameters at startup. This is a computationally expensive
4708 operation that consumes random pool entropy, so it is
4709 recommended that a persistent set of parameters be generated
4712 For x509 certificate credentials the directory will contain
4713 further files providing the x509 certificates. The certificates
4714 must be stored in PEM format, in filenames ca-cert.pem,
4715 ca-crl.pem (optional), server-cert.pem (only servers),
4716 server-key.pem (only servers), client-cert.pem (only clients),
4717 and client-key.pem (only clients).
4719 For the server-key.pem and client-key.pem files which contain
4720 sensitive private keys, it is possible to use an encrypted
4721 version by providing the passwordid parameter. This provides the
4722 ID of a previously created ``secret`` object containing the
4723 password for decryption.
4725 The priority parameter allows to override the global default
4726 priority used by gnutls. This can be useful if the system
4727 administrator needs to use a weaker set of crypto priorities for
4728 QEMU without potentially forcing the weakness onto all
4729 applications. Or conversely if one wants wants a stronger
4730 default for QEMU than for all other applications, they can do
4731 this through this parameter. Its format is a gnutls priority
4732 string as described at
4733 https://gnutls.org/manual/html_node/Priority-Strings.html.
4735 ``-object tls-cipher-suites,id=id,priority=priority``
4736 Creates a TLS cipher suites object, which can be used to control
4737 the TLS cipher/protocol algorithms that applications are permitted
4740 The ``id`` parameter is a unique ID which frontends will use to
4741 access the ordered list of permitted TLS cipher suites from the
4744 The ``priority`` parameter allows to override the global default
4745 priority used by gnutls. This can be useful if the system
4746 administrator needs to use a weaker set of crypto priorities for
4747 QEMU without potentially forcing the weakness onto all
4748 applications. Or conversely if one wants wants a stronger
4749 default for QEMU than for all other applications, they can do
4750 this through this parameter. Its format is a gnutls priority
4751 string as described at
4752 https://gnutls.org/manual/html_node/Priority-Strings.html.
4754 An example of use of this object is to control UEFI HTTPS Boot.
4755 The tls-cipher-suites object exposes the ordered list of permitted
4756 TLS cipher suites from the host side to the guest firmware, via
4757 fw_cfg. The list is represented as an array of IANA_TLS_CIPHER
4758 objects. The firmware uses the IANA_TLS_CIPHER array for configuring
4761 In the following example, the priority at which the host-side policy
4762 is retrieved is given by the ``priority`` property.
4763 Given that QEMU uses GNUTLS, ``priority=@SYSTEM`` may be used to
4764 refer to /etc/crypto-policies/back-ends/gnutls.config.
4769 -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \\
4770 -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0
4772 ``-object filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
4773 Interval t can't be
0, this filter batches the packet delivery
:
4774 all packets arriving
in a given interval on netdev netdevid are
4775 delayed until the end of the interval
. Interval is
in
4776 microseconds
. ``status`` is optional that indicate whether the
4777 netfilter is
on (enabled
) or
off (disabled
), the
default status
4778 for netfilter will be
'on'.
4780 queue all\|rx\|tx is an option that can be applied to any
4783 ``all``
: the filter is attached both to the receive and the
4784 transmit queue of the
netdev (default).
4786 ``rx``
: the filter is attached to the receive queue of the
4787 netdev
, where it will receive packets sent to the netdev
.
4789 ``tx``
: the filter is attached to the transmit queue of the
4790 netdev
, where it will receive packets sent by the netdev
.
4792 position head\|tail\|id
=<id
> is an option to specify where the
4793 filter should be inserted
in the filter list
. It can be applied
4796 ``head``
: the filter is inserted at the head of the filter list
,
4797 before any existing filters
.
4799 ``tail``
: the filter is inserted at the tail of the filter list
,
4800 behind any existing
filters (default).
4802 ``id
=<id
>``
: the filter is inserted before or behind the filter
4803 specified by
<id
>, see the insert option below
.
4805 insert behind\|before is an option to specify where to insert
4806 the
new filter relative to the one specified with
4807 position
=id
=<id
>. It can be applied to any netfilter
.
4809 ``before``
: insert before the specified filter
.
4811 ``behind``
: insert behind the specified
filter (default).
4813 ``
-object filter
-mirror
,id
=id
,netdev
=netdevid
,outdev
=chardevid
,queue
=all|rx|tx
[,vnet_hdr_support
][,position
=head|tail|id
=<id
>][,insert
=behind|before
]``
4814 filter
-mirror on netdev netdevid
,mirror net packet to
4815 chardevchardevid
, if it has the vnet\_hdr\_support flag
,
4816 filter
-mirror will mirror packet with vnet\_hdr\_len
.
4818 ``
-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
]``
4819 filter
-redirector on netdev netdevid
,redirect filter
's net
4820 packet to chardev chardevid,and redirect indev's packet to
4821 filter
.if it has the vnet\_hdr\_support flag
, filter
-redirector
4822 will redirect packet with vnet\_hdr\_len
. Create a
4823 filter
-redirector we need to differ outdev id from indev id
, id
4824 can not be the same
. we can just use indev or outdev
, but at
4825 least one of indev or outdev need to be specified
.
4827 ``
-object filter
-rewriter
,id
=id
,netdev
=netdevid
,queue
=all|rx|tx
,[vnet_hdr_support
][,position
=head|tail|id
=<id
>][,insert
=behind|before
]``
4828 Filter
-rewriter is a part of COLO project
.It will rewrite tcp
4829 packet to secondary from primary to keep secondary tcp
4830 connection
,and rewrite tcp packet to primary from secondary make
4831 tcp packet can be handled by client
.if it has the
4832 vnet\_hdr\_support flag
, we can parse packet with vnet header
.
4834 usage
: colo secondary
: -object
4835 filter
-redirector
,id
=f1
,netdev
=hn0
,queue
=tx
,indev
=red0
-object
4836 filter
-redirector
,id
=f2
,netdev
=hn0
,queue
=rx
,outdev
=red1
-object
4837 filter
-rewriter
,id
=rew0
,netdev
=hn0
,queue
=all
4839 ``
-object filter
-dump
,id
=id
,netdev
=dev
[,file
=filename
][,maxlen
=len
][,position
=head|tail|id
=<id
>][,insert
=behind|before
]``
4840 Dump the network traffic on netdev dev to the file specified by
4841 filename
. At most len
bytes (64k by
default) per packet are
4842 stored
. The file format is libpcap
, so it can be analyzed with
4843 tools such as tcpdump or Wireshark
.
4845 ``
-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
}]``
4846 Colo
-compare gets packet from primary\_in chardevid and
4847 secondary\_in
, then compare whether the payload of primary packet
4848 and secondary packet are the same
. If same
, it will output
4849 primary packet to out\_dev
, else it will notify COLO
-framework to
do
4850 checkpoint and send primary packet to out\_dev
. In order to
4851 improve efficiency
, we need to put the task of comparison
in
4852 another iothread
. If it has the vnet\_hdr\_support flag
,
4853 colo compare will send
/recv packet with vnet\_hdr\_len
.
4854 The compare\_timeout
=@
var{ms
} determines the maximum time of the
4855 colo
-compare hold the packet
. The expired\_scan\_cycle
=@
var{ms
}
4856 is to set the period of scanning expired primary node network packets
.
4857 The max\_queue\_size
=@
var{size
} is to set the max compare queue
4858 size depend on user environment
.
4859 If user want to use Xen COLO
, need to add the notify\_dev to
4860 notify Xen colo
-frame to
do checkpoint
.
4862 COLO
-compare must be used with the help of filter
-mirror
,
4863 filter
-redirector and filter
-rewriter
.
4870 -netdev tap
,id
=hn0
,vhost
=off
,script
=/etc
/qemu
-ifup
,downscript
=/etc
/qemu
-ifdown
4871 -device e1000
,id
=e0
,netdev
=hn0
,mac
=52:a4
:00:12:78:66
4872 -chardev socket
,id
=mirror0
,host
=3.3.3.3,port
=9003,server
=on
,wait
=off
4873 -chardev socket
,id
=compare1
,host
=3.3.3.3,port
=9004,server
=on
,wait
=off
4874 -chardev socket
,id
=compare0
,host
=3.3.3.3,port
=9001,server
=on
,wait
=off
4875 -chardev socket
,id
=compare0
-0,host
=3.3.3.3,port
=9001
4876 -chardev socket
,id
=compare_out
,host
=3.3.3.3,port
=9005,server
=on
,wait
=off
4877 -chardev socket
,id
=compare_out0
,host
=3.3.3.3,port
=9005
4878 -object iothread
,id
=iothread1
4879 -object filter
-mirror
,id
=m0
,netdev
=hn0
,queue
=tx
,outdev
=mirror0
4880 -object filter
-redirector
,netdev
=hn0
,id
=redire0
,queue
=rx
,indev
=compare_out
4881 -object filter
-redirector
,netdev
=hn0
,id
=redire1
,queue
=rx
,outdev
=compare0
4882 -object colo
-compare
,id
=comp0
,primary_in
=compare0
-0,secondary_in
=compare1
,outdev
=compare_out0
,iothread
=iothread1
4885 -netdev tap
,id
=hn0
,vhost
=off
,script
=/etc
/qemu
-ifup
,down script
=/etc
/qemu
-ifdown
4886 -device e1000
,netdev
=hn0
,mac
=52:a4
:00:12:78:66
4887 -chardev socket
,id
=red0
,host
=3.3.3.3,port
=9003
4888 -chardev socket
,id
=red1
,host
=3.3.3.3,port
=9004
4889 -object filter
-redirector
,id
=f1
,netdev
=hn0
,queue
=tx
,indev
=red0
4890 -object filter
-redirector
,id
=f2
,netdev
=hn0
,queue
=rx
,outdev
=red1
4896 -netdev tap
,id
=hn0
,vhost
=off
,script
=/etc
/qemu
-ifup
,downscript
=/etc
/qemu
-ifdown
4897 -device e1000
,id
=e0
,netdev
=hn0
,mac
=52:a4
:00:12:78:66
4898 -chardev socket
,id
=mirror0
,host
=3.3.3.3,port
=9003,server
=on
,wait
=off
4899 -chardev socket
,id
=compare1
,host
=3.3.3.3,port
=9004,server
=on
,wait
=off
4900 -chardev socket
,id
=compare0
,host
=3.3.3.3,port
=9001,server
=on
,wait
=off
4901 -chardev socket
,id
=compare0
-0,host
=3.3.3.3,port
=9001
4902 -chardev socket
,id
=compare_out
,host
=3.3.3.3,port
=9005,server
=on
,wait
=off
4903 -chardev socket
,id
=compare_out0
,host
=3.3.3.3,port
=9005
4904 -chardev socket
,id
=notify_way
,host
=3.3.3.3,port
=9009,server
=on
,wait
=off
4905 -object filter
-mirror
,id
=m0
,netdev
=hn0
,queue
=tx
,outdev
=mirror0
4906 -object filter
-redirector
,netdev
=hn0
,id
=redire0
,queue
=rx
,indev
=compare_out
4907 -object filter
-redirector
,netdev
=hn0
,id
=redire1
,queue
=rx
,outdev
=compare0
4908 -object iothread
,id
=iothread1
4909 -object colo
-compare
,id
=comp0
,primary_in
=compare0
-0,secondary_in
=compare1
,outdev
=compare_out0
,notify_dev
=nofity_way
,iothread
=iothread1
4912 -netdev tap
,id
=hn0
,vhost
=off
,script
=/etc
/qemu
-ifup
,down script
=/etc
/qemu
-ifdown
4913 -device e1000
,netdev
=hn0
,mac
=52:a4
:00:12:78:66
4914 -chardev socket
,id
=red0
,host
=3.3.3.3,port
=9003
4915 -chardev socket
,id
=red1
,host
=3.3.3.3,port
=9004
4916 -object filter
-redirector
,id
=f1
,netdev
=hn0
,queue
=tx
,indev
=red0
4917 -object filter
-redirector
,id
=f2
,netdev
=hn0
,queue
=rx
,outdev
=red1
4919 If you want to know the detail of above command line
, you can
4920 read the colo
-compare git log
.
4922 ``
-object cryptodev
-backend
-builtin
,id
=id
[,queues
=queues
]``
4923 Creates a cryptodev backend which executes crypto opreation from
4924 the QEMU cipher APIS
. The id parameter is a unique ID that will
4925 be used to reference
this cryptodev backend from the
4926 ``virtio
-crypto`` device
. The queues parameter is optional
,
4927 which specify the queue number of cryptodev backend
, the
default
4934 -object cryptodev
-backend
-builtin
,id
=cryptodev0
\\
4935 -device virtio
-crypto
-pci
,id
=crypto0
,cryptodev
=cryptodev0
\\
4938 ``
-object cryptodev
-vhost
-user
,id
=id
,chardev
=chardevid
[,queues
=queues
]``
4939 Creates a vhost
-user cryptodev backend
, backed by a chardev
4940 chardevid
. The id parameter is a unique ID that will be used to
4941 reference
this cryptodev backend from the ``virtio
-crypto``
4942 device
. The chardev should be a unix domain socket backed one
.
4943 The vhost
-user uses a specifically defined protocol to pass
4944 vhost ioctl replacement messages to an application on the other
4945 end of the socket
. The queues parameter is optional
, which
4946 specify the queue number of cryptodev backend
for multiqueue
4947 vhost
-user
, the
default of queues is
1.
4953 -chardev socket
,id
=chardev0
,path
=/path
/to
/socket
\\
4954 -object cryptodev
-vhost
-user
,id
=cryptodev0
,chardev
=chardev0
\\
4955 -device virtio
-crypto
-pci
,id
=crypto0
,cryptodev
=cryptodev0
\\
4958 ``
-object secret
,id
=id
,data
=string
,format
=raw|base64
[,keyid
=secretid
,iv
=string
]``
4960 ``
-object secret
,id
=id
,file
=filename
,format
=raw|base64
[,keyid
=secretid
,iv
=string
]``
4961 Defines a secret to store a password
, encryption key
, or some
4962 other sensitive data
. The sensitive data can either be passed
4963 directly via the data parameter
, or indirectly via the file
4964 parameter
. Using the data parameter is insecure unless the
4965 sensitive data is encrypted
.
4967 The sensitive data can be provided
in raw
format (the
default),
4968 or base64
. When encoded as JSON
, the raw format only supports
4969 valid UTF
-8 characters
, so base64 is recommended
for sending
4970 binary data
. QEMU will convert from which ever format is
4971 provided to the format it needs internally
. eg
, an RBD password
4972 can be provided
in raw format
, even though it will be base64
4973 encoded when passed onto the RBD sever
.
4975 For added protection
, it is possible to encrypt the data
4976 associated with a secret
using the AES
-256-CBC cipher
. Use of
4977 encryption is indicated by providing the keyid and iv
4978 parameters
. The keyid parameter provides the ID of a previously
4979 defined secret that contains the AES
-256 decryption key
. This
4980 key should be
32-bytes long and be base64 encoded
. The iv
4981 parameter provides the random initialization vector used
for
4982 encryption of
this particular secret and should be a base64
4983 encrypted string of the
16-byte IV
.
4985 The
simplest (insecure
) usage is to provide the secret
inline
4989 # |qemu_system|
-object secret
,id
=sec0
,data
=letmein
,format
=raw
4991 The simplest secure usage is to provide the secret via a file
4993 # printf
"letmein" > mypasswd
.txt # QEMU\_SYSTEM\_MACRO
-object
4994 secret
,id
=sec0
,file
=mypasswd
.txt
,format
=raw
4996 For greater security
, AES
-256-CBC should be used
. To illustrate
4997 usage
, consider the openssl command line tool which can encrypt
4998 the data
. Note that when encrypting
, the plaintext must be
4999 padded to the cipher block
size (32 bytes
) using the standard
5000 PKCS#
5/6 compatible padding algorithm
.
5002 First a master key needs to be created
in base64 encoding
:
5006 # openssl rand
-base64
32 > key
.b64
5007 # KEY
=$
(base64
-d key
.b64 | hexdump
-v
-e
'/1 "%02X"')
5009 Each secret to be encrypted needs to have a random
5010 initialization vector generated
. These
do not need to be kept
5015 # openssl rand
-base64
16 > iv
.b64
5016 # IV
=$
(base64
-d iv
.b64 | hexdump
-v
-e
'/1 "%02X"')
5018 The secret to be defined can now be encrypted
, in this case
5019 we
're telling openssl to base64 encode the result, but it could
5020 be left as raw bytes if desired.
5024 # SECRET=$(printf "letmein" |
5025 openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
5027 When launching QEMU, create a master secret pointing to
5028 ``key.b64`` and specify that to be used to decrypt the user
5029 password. Pass the contents of ``iv.b64`` to the second secret
5034 -object secret,id=secmaster0,format=base64,file=key.b64 \\
5035 -object secret,id=sec0,keyid=secmaster0,format=base64,\\
5036 data=$SECRET,iv=$(<iv.b64)
5038 ``-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]``
5039 Create a Secure Encrypted Virtualization (SEV) guest object,
5040 which can be used to provide the guest memory encryption support
5043 When memory encryption is enabled, one of the physical address
5044 bit (aka the C-bit) is utilized to mark if a memory page is
5045 protected. The ``cbitpos`` is used to provide the C-bit
5046 position. The C-bit position is Host family dependent hence user
5047 must provide this value. On EPYC, the value should be 47.
5049 When memory encryption is enabled, we loose certain bits in
5050 physical address space. The ``reduced-phys-bits`` is used to
5051 provide the number of bits we loose in physical address space.
5052 Similar to C-bit, the value is Host family dependent. On EPYC,
5053 the value should be 5.
5055 The ``sev-device`` provides the device file to use for
5056 communicating with the SEV firmware running inside AMD Secure
5057 Processor. The default device is '/dev
/sev
'. If hardware
5058 supports memory encryption then /dev/sev devices are created by
5061 The ``policy`` provides the guest policy to be enforced by the
5062 SEV firmware and restrict what configuration and operational
5063 commands can be performed on this guest by the hypervisor. The
5064 policy should be provided by the guest owner and is bound to the
5065 guest and cannot be changed throughout the lifetime of the
5066 guest. The default is 0.
5068 If guest ``policy`` allows sharing the key with another SEV
5069 guest then ``handle`` can be use to provide handle of the guest
5070 from which to share the key.
5072 The ``dh-cert-file`` and ``session-file`` provides the guest
5073 owner's Public Diffie
-Hillman key defined
in SEV spec
. The PDH
5074 and session parameters are used
for establishing a cryptographic
5075 session with the guest owner to negotiate keys used
for
5076 attestation
. The file must be encoded
in base64
.
5078 e
.g to launch a SEV guest
5082 # |qemu_system_x86|
\\
5084 -object sev
-guest
,id
=sev0
,cbitpos
=47,reduced
-phys
-bits
=5 \\
5085 -machine
...,memory
-encryption
=sev0
\\
5088 ``
-object authz
-simple
,id
=id
,identity
=string``
5089 Create an authorization object that will control access to
5092 The ``identity`` parameter is identifies the user and its format
5093 depends on the network service that authorization object is
5094 associated with
. For authorizing based on TLS x509 certificates
,
5095 the identity must be the x509 distinguished name
. Note that care
5096 must be taken to escape any commas
in the distinguished name
.
5098 An example authorization object to validate a x509 distinguished
5099 name would look like
:
5105 -object
'authz-simple,id=auth0,identity=CN=laptop.example.com,,O=Example Org,,L=London,,ST=London,,C=GB' \\
5108 Note the use of quotes due to the x509 distinguished name
5109 containing whitespace
, and escaping of
','.
5111 ``
-object authz
-listfile
,id
=id
,filename
=path
,refresh
=on|off``
5112 Create an authorization object that will control access to
5115 The ``filename`` parameter is the fully qualified path to a file
5116 containing the access control list rules
in JSON format
.
5118 An example set of rules that match against SASL usernames might
5125 { "match": "fred", "policy": "allow", "format": "exact" },
5126 { "match": "bob", "policy": "allow", "format": "exact" },
5127 { "match": "danb", "policy": "deny", "format": "glob" },
5128 { "match": "dan*", "policy": "allow", "format": "exact" },
5133 When checking access the object will iterate over all the rules
5134 and the first rule to match will have its ``policy`` value
5135 returned as the result
. If no rules match
, then the
default
5136 ``policy`` value is returned
.
5138 The rules can either be an exact string match
, or they can use
5139 the simple UNIX glob pattern matching to allow wildcards to be
5142 If ``refresh`` is set to
true the file will be monitored and
5143 automatically reloaded whenever its content changes
.
5145 As with the ``authz
-simple`` object
, the format of the identity
5146 strings being matched depends on the network service
, but is
5147 usually a TLS x509 distinguished name
, or a SASL username
.
5149 An example authorization object to validate a SASL username
5156 -object authz
-simple
,id
=auth0
,filename
=/etc
/qemu
/vnc
-sasl
.acl
,refresh
=on
\\
5159 ``
-object authz
-pam
,id
=id
,service
=string``
5160 Create an authorization object that will control access to
5163 The ``service`` parameter provides the name of a PAM service to
5164 use
for authorization
. It requires that a file
5165 ``
/etc
/pam
.d
/service`` exist to provide the configuration
for
5166 the ``account`` subsystem
.
5168 An example authorization object to validate a TLS x509
5169 distinguished name would look like
:
5175 -object authz
-pam
,id
=auth0
,service
=qemu
-vnc
\\
5178 There would then be a corresponding config file
for PAM at
5179 ``
/etc
/pam
.d
/qemu
-vnc`` that contains
:
5183 account requisite pam_listfile
.so item
=user sense
=allow \
5184 file
=/etc
/qemu
/vnc
.allow
5186 Finally the ``
/etc
/qemu
/vnc
.allow`` file would contain the list
5187 of x509 distingished names that are permitted access
5191 CN
=laptop
.example
.com
,O
=Example Home
,L
=London
,ST
=London
,C
=GB
5193 ``
-object iothread
,id
=id
,poll
-max
-ns
=poll
-max
-ns
,poll
-grow
=poll
-grow
,poll
-shrink
=poll
-shrink``
5194 Creates a dedicated event loop thread that devices can be
5195 assigned to
. This is known as an IOThread
. By
default device
5196 emulation happens
in vCPU threads or the main event loop thread
.
5197 This can become a scalability bottleneck
. IOThreads allow device
5198 emulation and I
/O to run on other host CPUs
.
5200 The ``id`` parameter is a unique ID that will be used to
5201 reference
this IOThread from ``
-device
...,iothread
=id``
.
5202 Multiple devices can be assigned to an IOThread
. Note that not
5203 all devices support an ``iothread`` parameter
.
5205 The ``query
-iothreads`` QMP command lists IOThreads and reports
5206 their thread IDs so that the user can configure host CPU
5209 IOThreads use an adaptive polling algorithm to reduce event loop
5210 latency
. Instead of entering a blocking system call to monitor
5211 file descriptors and then pay the cost of being woken up when an
5212 event occurs
, the polling algorithm spins waiting
for events
for
5213 a short time
. The algorithm
's default parameters are suitable
5214 for many cases but can be adjusted based on knowledge of the
5215 workload and/or host device latency.
5217 The ``poll-max-ns`` parameter is the maximum number of
5218 nanoseconds to busy wait for events. Polling can be disabled by
5219 setting this value to 0.
5221 The ``poll-grow`` parameter is the multiplier used to increase
5222 the polling time when the algorithm detects it is missing events
5223 due to not polling long enough.
5225 The ``poll-shrink`` parameter is the divisor used to decrease
5226 the polling time when the algorithm detects it is spending too
5227 long polling without encountering events.
5229 The polling parameters can be modified at run-time using the
5230 ``qom-set`` command (where ``iothread1`` is the IOThread's
5235 (qemu
) qom
-set
/objects
/iothread1 poll
-max
-ns
100000
5239 HXCOMM This is the last statement
. Insert
new options before
this line
!