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qmp-commands.txt
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QMP Supported Commands
----------------------
This document describes all commands currently supported by QMP.
Most of the time their usage is exactly the same as in the user Monitor, this
means that any other document which also describe commands (the manpage,
QEMU's manual, etc) can and should be consulted.
QMP has two types of commands: regular and query commands. Regular commands
usually change the Virtual Machine's state someway, while query commands just
return information. The sections below are divided accordingly.
It's important to observe that all communication examples are formatted in
a reader-friendly way, so that they're easier to understand. However, in real
protocol usage, they're emitted as a single line.
Also, the following notation is used to denote data flow:
-> data issued by the Client
<- Server data response
Please, refer to the QMP specification (docs/qmp-spec.txt) for detailed
information on the Server command and response formats.
NOTE: This document is temporary and will be replaced soon.
1. Stability Considerations
===========================
The current QMP command set (described in this file) may be useful for a
number of use cases, however it's limited and several commands have bad
defined semantics, specially with regard to command completion.
These problems are going to be solved incrementally in the next QEMU releases
and we're going to establish a deprecation policy for badly defined commands.
If you're planning to adopt QMP, please observe the following:
1. The deprecation policy will take effect and be documented soon, please
check the documentation of each used command as soon as a new release of
QEMU is available
2. DO NOT rely on anything which is not explicit documented
3. Errors, in special, are not documented. Applications should NOT check
for specific errors classes or data (it's strongly recommended to only
check for the "error" key)
2. Regular Commands
===================
Server's responses in the examples below are always a success response, please
refer to the QMP specification for more details on error responses.
quit
----
Quit the emulator.
Arguments: None.
Example:
-> { "execute": "quit" }
<- { "return": {} }
eject
-----
Eject a removable medium.
Arguments:
- "force": force ejection (json-bool, optional)
- "device": block device name (deprecated, use @id instead)
(json-string, optional)
- "id": the name or QOM path of the guest device (json-string, optional)
Example:
-> { "execute": "eject", "arguments": { "id": "ide0-1-0" } }
<- { "return": {} }
Note: The "force" argument defaults to false.
change
------
Change a removable medium or VNC configuration.
Arguments:
- "device": device name (json-string)
- "target": filename or item (json-string)
- "arg": additional argument (json-string, optional)
Examples:
1. Change a removable medium
-> { "execute": "change",
"arguments": { "device": "ide1-cd0",
"target": "/srv/images/Fedora-12-x86_64-DVD.iso" } }
<- { "return": {} }
2. Change VNC password
-> { "execute": "change",
"arguments": { "device": "vnc", "target": "password",
"arg": "foobar1" } }
<- { "return": {} }
screendump
----------
Save screen into PPM image.
Arguments:
- "filename": file path (json-string)
Example:
-> { "execute": "screendump", "arguments": { "filename": "/tmp/image" } }
<- { "return": {} }
stop
----
Stop the emulator.
Arguments: None.
Example:
-> { "execute": "stop" }
<- { "return": {} }
cont
----
Resume emulation.
Arguments: None.
Example:
-> { "execute": "cont" }
<- { "return": {} }
system_wakeup
-------------
Wakeup guest from suspend.
Arguments: None.
Example:
-> { "execute": "system_wakeup" }
<- { "return": {} }
system_reset
------------
Reset the system.
Arguments: None.
Example:
-> { "execute": "system_reset" }
<- { "return": {} }
system_powerdown
----------------
Send system power down event.
Arguments: None.
Example:
-> { "execute": "system_powerdown" }
<- { "return": {} }
device_add
----------
Add a device.
Arguments:
- "driver": the name of the new device's driver (json-string)
- "bus": the device's parent bus (device tree path, json-string, optional)
- "id": the device's ID, must be unique (json-string)
- device properties
Example:
-> { "execute": "device_add", "arguments": { "driver": "e1000", "id": "net1" } }
<- { "return": {} }
Notes:
(1) For detailed information about this command, please refer to the
'docs/qdev-device-use.txt' file.
(2) It's possible to list device properties by running QEMU with the
"-device DEVICE,\?" command-line argument, where DEVICE is the device's name
device_del
----------
Remove a device.
Arguments:
- "id": the device's ID or QOM path (json-string)
Example:
-> { "execute": "device_del", "arguments": { "id": "net1" } }
<- { "return": {} }
Example:
-> { "execute": "device_del", "arguments": { "id": "/machine/peripheral-anon/device[0]" } }
<- { "return": {} }
send-key
----------
Send keys to VM.
Arguments:
keys array:
- "key": key sequence (a json-array of key union values,
union can be number or qcode enum)
- hold-time: time to delay key up events, milliseconds. Defaults to 100
(json-int, optional)
Example:
-> { "execute": "send-key",
"arguments": { "keys": [ { "type": "qcode", "data": "ctrl" },
{ "type": "qcode", "data": "alt" },
{ "type": "qcode", "data": "delete" } ] } }
<- { "return": {} }
cpu
---
Set the default CPU.
Arguments:
- "index": the CPU's index (json-int)
Example:
-> { "execute": "cpu", "arguments": { "index": 0 } }
<- { "return": {} }
Note: CPUs' indexes are obtained with the 'query-cpus' command.
cpu-add
-------
Adds virtual cpu
Arguments:
- "id": cpu id (json-int)
Example:
-> { "execute": "cpu-add", "arguments": { "id": 2 } }
<- { "return": {} }
memsave
-------
Save to disk virtual memory dump starting at 'val' of size 'size'.
Arguments:
- "val": the starting address (json-int)
- "size": the memory size, in bytes (json-int)
- "filename": file path (json-string)
- "cpu": virtual CPU index (json-int, optional)
Example:
-> { "execute": "memsave",
"arguments": { "val": 10,
"size": 100,
"filename": "/tmp/virtual-mem-dump" } }
<- { "return": {} }
pmemsave
--------
Save to disk physical memory dump starting at 'val' of size 'size'.
Arguments:
- "val": the starting address (json-int)
- "size": the memory size, in bytes (json-int)
- "filename": file path (json-string)
Example:
-> { "execute": "pmemsave",
"arguments": { "val": 10,
"size": 100,
"filename": "/tmp/physical-mem-dump" } }
<- { "return": {} }
inject-nmi
----------
Inject an NMI on the default CPU (x86/s390) or all CPUs (ppc64).
Arguments: None.
Example:
-> { "execute": "inject-nmi" }
<- { "return": {} }
Note: inject-nmi fails when the guest doesn't support injecting.
ringbuf-write
-------------
Write to a ring buffer character device.
Arguments:
- "device": ring buffer character device name (json-string)
- "data": data to write (json-string)
- "format": data format (json-string, optional)
- Possible values: "utf8" (default), "base64"
Example:
-> { "execute": "ringbuf-write",
"arguments": { "device": "foo",
"data": "abcdefgh",
"format": "utf8" } }
<- { "return": {} }
ringbuf-read
-------------
Read from a ring buffer character device.
Arguments:
- "device": ring buffer character device name (json-string)
- "size": how many bytes to read at most (json-int)
- Number of data bytes, not number of characters in encoded data
- "format": data format (json-string, optional)
- Possible values: "utf8" (default), "base64"
- Naturally, format "utf8" works only when the ring buffer
contains valid UTF-8 text. Invalid UTF-8 sequences get
replaced. Bug: replacement doesn't work. Bug: can screw
up on encountering NUL characters, after the ring buffer
lost data, and when reading stops because the size limit
is reached.
Example:
-> { "execute": "ringbuf-read",
"arguments": { "device": "foo",
"size": 1000,
"format": "utf8" } }
<- {"return": "abcdefgh"}
xen-save-devices-state
-------
Save the state of all devices to file. The RAM and the block devices
of the VM are not saved by this command.
Arguments:
- "filename": the file to save the state of the devices to as binary
data. See xen-save-devices-state.txt for a description of the binary
format.
Example:
-> { "execute": "xen-save-devices-state",
"arguments": { "filename": "/tmp/save" } }
<- { "return": {} }
xen-load-devices-state
----------------------
Load the state of all devices from file. The RAM and the block devices
of the VM are not loaded by this command.
Arguments:
- "filename": the file to load the state of the devices from as binary
data. See xen-save-devices-state.txt for a description of the binary
format.
Example:
-> { "execute": "xen-load-devices-state",
"arguments": { "filename": "/tmp/resume" } }
<- { "return": {} }
xen-set-global-dirty-log
-------
Enable or disable the global dirty log mode.
Arguments:
- "enable": Enable it or disable it.
Example:
-> { "execute": "xen-set-global-dirty-log",
"arguments": { "enable": true } }
<- { "return": {} }
migrate
-------
Migrate to URI.
Arguments:
- "blk": block migration, full disk copy (json-bool, optional)
- "inc": incremental disk copy (json-bool, optional)
- "uri": Destination URI (json-string)
Example:
-> { "execute": "migrate", "arguments": { "uri": "tcp:0:4446" } }
<- { "return": {} }
Notes:
(1) The 'query-migrate' command should be used to check migration's progress
and final result (this information is provided by the 'status' member)
(2) All boolean arguments default to false
(3) The user Monitor's "detach" argument is invalid in QMP and should not
be used
migrate_cancel
--------------
Cancel the current migration.
Arguments: None.
Example:
-> { "execute": "migrate_cancel" }
<- { "return": {} }
migrate-incoming
----------------
Continue an incoming migration
Arguments:
- "uri": Source/listening URI (json-string)
Example:
-> { "execute": "migrate-incoming", "arguments": { "uri": "tcp::4446" } }
<- { "return": {} }
Notes:
(1) QEMU must be started with -incoming defer to allow migrate-incoming to
be used
(2) The uri format is the same as for -incoming
migrate-set-cache-size
----------------------
Set cache size to be used by XBZRLE migration, the cache size will be rounded
down to the nearest power of 2
Arguments:
- "value": cache size in bytes (json-int)
Example:
-> { "execute": "migrate-set-cache-size", "arguments": { "value": 536870912 } }
<- { "return": {} }
migrate-start-postcopy
----------------------
Switch an in-progress migration to postcopy mode. Ignored after the end of
migration (or once already in postcopy).
Example:
-> { "execute": "migrate-start-postcopy" }
<- { "return": {} }
query-migrate-cache-size
------------------------
Show cache size to be used by XBZRLE migration
returns a json-object with the following information:
- "size" : json-int
Example:
-> { "execute": "query-migrate-cache-size" }
<- { "return": 67108864 }
migrate_set_speed
-----------------
Set maximum speed for migrations.
Arguments:
- "value": maximum speed, in bytes per second (json-int)
Example:
-> { "execute": "migrate_set_speed", "arguments": { "value": 1024 } }
<- { "return": {} }
migrate_set_downtime
--------------------
Set maximum tolerated downtime (in seconds) for migrations.
Arguments:
- "value": maximum downtime (json-number)
Example:
-> { "execute": "migrate_set_downtime", "arguments": { "value": 0.1 } }
<- { "return": {} }
x-colo-lost-heartbeat
--------------------
Tell COLO that heartbeat is lost, a failover or takeover is needed.
Example:
-> { "execute": "x-colo-lost-heartbeat" }
<- { "return": {} }
client_migrate_info
-------------------
Set migration information for remote display. This makes the server
ask the client to automatically reconnect using the new parameters
once migration finished successfully. Only implemented for SPICE.
Arguments:
- "protocol": must be "spice" (json-string)
- "hostname": migration target hostname (json-string)
- "port": spice tcp port for plaintext channels (json-int, optional)
- "tls-port": spice tcp port for tls-secured channels (json-int, optional)
- "cert-subject": server certificate subject (json-string, optional)
Example:
-> { "execute": "client_migrate_info",
"arguments": { "protocol": "spice",
"hostname": "virt42.lab.kraxel.org",
"port": 1234 } }
<- { "return": {} }
dump
Dump guest memory to file. The file can be processed with crash or gdb.
Arguments:
- "paging": do paging to get guest's memory mapping (json-bool)
- "protocol": destination file(started with "file:") or destination file
descriptor (started with "fd:") (json-string)
- "detach": if specified, command will return immediately, without waiting
for the dump to finish. The user can track progress using
"query-dump". (json-bool)
- "begin": the starting physical address. It's optional, and should be specified
with length together (json-int)
- "length": the memory size, in bytes. It's optional, and should be specified
with begin together (json-int)
- "format": the format of guest memory dump. It's optional, and can be
elf|kdump-zlib|kdump-lzo|kdump-snappy, but non-elf formats will
conflict with paging and filter, ie. begin and length (json-string)
Example:
-> { "execute": "dump-guest-memory", "arguments": { "protocol": "fd:dump" } }
<- { "return": {} }
Notes:
(1) All boolean arguments default to false
query-dump-guest-memory-capability
----------
Show available formats for 'dump-guest-memory'
Example:
-> { "execute": "query-dump-guest-memory-capability" }
<- { "return": { "formats":
["elf", "kdump-zlib", "kdump-lzo", "kdump-snappy"] }
query-dump
----------
Query background dump status.
Arguments: None.
Example:
-> { "execute": "query-dump" }
<- { "return": { "status": "active", "completed": 1024000,
"total": 2048000 } }
dump-skeys
----------
Save guest storage keys to file.
Arguments:
- "filename": file path (json-string)
Example:
-> { "execute": "dump-skeys", "arguments": { "filename": "/tmp/skeys" } }
<- { "return": {} }
netdev_add
----------
Add host network device.
Arguments:
- "type": the device type, "tap", "user", ... (json-string)
- "id": the device's ID, must be unique (json-string)
- device options
Example:
-> { "execute": "netdev_add",
"arguments": { "type": "user", "id": "netdev1",
"dnssearch": "example.org" } }
<- { "return": {} }
Note: The supported device options are the same ones supported by the '-netdev'
command-line argument, which are listed in the '-help' output or QEMU's
manual
netdev_del
----------
Remove host network device.
Arguments:
- "id": the device's ID, must be unique (json-string)
Example:
-> { "execute": "netdev_del", "arguments": { "id": "netdev1" } }
<- { "return": {} }
object-add
----------
Create QOM object.
Arguments:
- "qom-type": the object's QOM type, i.e. the class name (json-string)
- "id": the object's ID, must be unique (json-string)
- "props": a dictionary of object property values (optional, json-dict)
Example:
-> { "execute": "object-add", "arguments": { "qom-type": "rng-random", "id": "rng1",
"props": { "filename": "/dev/hwrng" } } }
<- { "return": {} }
object-del
----------
Remove QOM object.
Arguments:
- "id": the object's ID (json-string)
Example:
-> { "execute": "object-del", "arguments": { "id": "rng1" } }
<- { "return": {} }
block_resize
------------
Resize a block image while a guest is running.
Arguments:
- "device": the device's ID, must be unique (json-string)
- "node-name": the node name in the block driver state graph (json-string)
- "size": new size
Example:
-> { "execute": "block_resize", "arguments": { "device": "scratch", "size": 1073741824 } }
<- { "return": {} }
block-stream
------------
Copy data from a backing file into a block device.
Arguments:
- "job-id": Identifier for the newly-created block job. If omitted,
the device name will be used. (json-string, optional)
- "device": The device name or node-name of a root node (json-string)
- "base": The file name of the backing image above which copying starts.
It cannot be set if 'base-node' is also set (json-string, optional)
- "base-node": the node name of the backing image above which copying starts.
It cannot be set if 'base' is also set.
(json-string, optional) (Since 2.8)
- "backing-file": The backing file string to write into the active layer. This
filename is not validated.
If a pathname string is such that it cannot be resolved by
QEMU, that means that subsequent QMP or HMP commands must use
node-names for the image in question, as filename lookup
methods will fail.
If not specified, QEMU will automatically determine the
backing file string to use, or error out if there is no
obvious choice. Care should be taken when specifying the
string, to specify a valid filename or protocol.
(json-string, optional) (Since 2.1)
- "speed": the maximum speed, in bytes per second (json-int, optional)
- "on-error": the action to take on an error (default 'report'). 'stop' and
'enospc' can only be used if the block device supports io-status.
(json-string, optional) (Since 2.1)
Example:
-> { "execute": "block-stream", "arguments": { "device": "virtio0",
"base": "/tmp/master.qcow2" } }
<- { "return": {} }
block-commit
------------
Live commit of data from overlay image nodes into backing nodes - i.e., writes
data between 'top' and 'base' into 'base'.
Arguments:
- "job-id": Identifier for the newly-created block job. If omitted,
the device name will be used. (json-string, optional)
- "device": The device name or node-name of a root node (json-string)
- "base": The file name of the backing image to write data into.
If not specified, this is the deepest backing image
(json-string, optional)
- "top": The file name of the backing image within the image chain,
which contains the topmost data to be committed down. If
not specified, this is the active layer. (json-string, optional)
- backing-file: The backing file string to write into the overlay
image of 'top'. If 'top' is the active layer,
specifying a backing file string is an error. This
filename is not validated.
If a pathname string is such that it cannot be
resolved by QEMU, that means that subsequent QMP or
HMP commands must use node-names for the image in
question, as filename lookup methods will fail.
If not specified, QEMU will automatically determine
the backing file string to use, or error out if
there is no obvious choice. Care should be taken
when specifying the string, to specify a valid
filename or protocol.
(json-string, optional) (Since 2.1)
If top == base, that is an error.
If top == active, the job will not be completed by itself,
user needs to complete the job with the block-job-complete
command after getting the ready event. (Since 2.0)
If the base image is smaller than top, then the base image
will be resized to be the same size as top. If top is
smaller than the base image, the base will not be
truncated. If you want the base image size to match the
size of the smaller top, you can safely truncate it
yourself once the commit operation successfully completes.
(json-string)
- "speed": the maximum speed, in bytes per second (json-int, optional)
Example:
-> { "execute": "block-commit", "arguments": { "device": "virtio0",
"top": "/tmp/snap1.qcow2" } }
<- { "return": {} }
drive-backup
------------
Start a point-in-time copy of a block device to a new destination. The
status of ongoing drive-backup operations can be checked with
query-block-jobs where the BlockJobInfo.type field has the value 'backup'.
The operation can be stopped before it has completed using the
block-job-cancel command.
Arguments:
- "job-id": Identifier for the newly-created block job. If omitted,
the device name will be used. (json-string, optional)
- "device": the device name or node-name of a root node which should be copied.
(json-string)
- "target": the target of the new image. If the file exists, or if it is a
device, the existing file/device will be used as the new
destination. If it does not exist, a new file will be created.
(json-string)
- "format": the format of the new destination, default is to probe if 'mode' is
'existing', else the format of the source
(json-string, optional)
- "sync": what parts of the disk image should be copied to the destination;
possibilities include "full" for all the disk, "top" for only the sectors
allocated in the topmost image, "incremental" for only the dirty sectors in
the bitmap, or "none" to only replicate new I/O (MirrorSyncMode).
- "bitmap": dirty bitmap name for sync==incremental. Must be present if sync
is "incremental", must NOT be present otherwise.
- "mode": whether and how QEMU should create a new image
(NewImageMode, optional, default 'absolute-paths')
- "speed": the maximum speed, in bytes per second (json-int, optional)
- "compress": true to compress data, if the target format supports it.
(json-bool, optional, default false)
- "on-source-error": the action to take on an error on the source, default
'report'. 'stop' and 'enospc' can only be used
if the block device supports io-status.
(BlockdevOnError, optional)
- "on-target-error": the action to take on an error on the target, default
'report' (no limitations, since this applies to
a different block device than device).
(BlockdevOnError, optional)
Example:
-> { "execute": "drive-backup", "arguments": { "device": "drive0",
"sync": "full",
"target": "backup.img" } }
<- { "return": {} }
blockdev-backup
---------------
The device version of drive-backup: this command takes an existing named device
as backup target.
Arguments:
- "job-id": Identifier for the newly-created block job. If omitted,
the device name will be used. (json-string, optional)
- "device": the device name or node-name of a root node which should be copied.
(json-string)
- "target": the name of the backup target device. (json-string)
- "sync": what parts of the disk image should be copied to the destination;
possibilities include "full" for all the disk, "top" for only the
sectors allocated in the topmost image, or "none" to only replicate
new I/O (MirrorSyncMode).
- "speed": the maximum speed, in bytes per second (json-int, optional)
- "compress": true to compress data, if the target format supports it.
(json-bool, optional, default false)
- "on-source-error": the action to take on an error on the source, default
'report'. 'stop' and 'enospc' can only be used
if the block device supports io-status.
(BlockdevOnError, optional)
- "on-target-error": the action to take on an error on the target, default
'report' (no limitations, since this applies to
a different block device than device).
(BlockdevOnError, optional)
Example:
-> { "execute": "blockdev-backup", "arguments": { "device": "src-id",
"sync": "full",
"target": "tgt-id" } }
<- { "return": {} }
transaction
-----------
Atomically operate on one or more block devices. Operations that are
currently supported:
- drive-backup
- blockdev-backup
- blockdev-snapshot-sync
- blockdev-snapshot-internal-sync
- abort
- block-dirty-bitmap-add
- block-dirty-bitmap-clear
Refer to the qemu/qapi-schema.json file for minimum required QEMU
versions for these operations. A list of dictionaries is accepted,
that contains the actions to be performed. If there is any failure
performing any of the operations, all operations for the group are
abandoned.
For external snapshots, the dictionary contains the device, the file to use for
the new snapshot, and the format. The default format, if not specified, is
qcow2.
Each new snapshot defaults to being created by QEMU (wiping any
contents if the file already exists), but it is also possible to reuse
an externally-created file. In the latter case, you should ensure that
the new image file has the same contents as the current one; QEMU cannot
perform any meaningful check. Typically this is achieved by using the
current image file as the backing file for the new image.
On failure, the original disks pre-snapshot attempt will be used.
For internal snapshots, the dictionary contains the device and the snapshot's
name. If an internal snapshot matching name already exists, the request will
be rejected. Only some image formats support it, for example, qcow2, rbd,
and sheepdog.
On failure, qemu will try delete the newly created internal snapshot in the
transaction. When an I/O error occurs during deletion, the user needs to fix
it later with qemu-img or other command.
Arguments:
actions array:
- "type": the operation to perform (json-string). Possible
values: "drive-backup", "blockdev-backup",
"blockdev-snapshot-sync",
"blockdev-snapshot-internal-sync",
"abort", "block-dirty-bitmap-add",
"block-dirty-bitmap-clear"
- "data": a dictionary. The contents depend on the value
of "type". When "type" is "blockdev-snapshot-sync":
- "device": device name to snapshot (json-string)
- "node-name": graph node name to snapshot (json-string)
- "snapshot-file": name of new image file (json-string)
- "snapshot-node-name": graph node name of the new snapshot (json-string)
- "format": format of new image (json-string, optional)
- "mode": whether and how QEMU should create the snapshot file
(NewImageMode, optional, default "absolute-paths")
When "type" is "blockdev-snapshot-internal-sync":
- "device": the device name or node-name of a root node to snapshot
(json-string)
- "name": name of the new snapshot (json-string)
Example:
-> { "execute": "transaction",
"arguments": { "actions": [
{ "type": "blockdev-snapshot-sync", "data" : { "device": "ide-hd0",
"snapshot-file": "/some/place/my-image",
"format": "qcow2" } },
{ "type": "blockdev-snapshot-sync", "data" : { "node-name": "myfile",
"snapshot-file": "/some/place/my-image2",
"snapshot-node-name": "node3432",
"mode": "existing",
"format": "qcow2" } },
{ "type": "blockdev-snapshot-sync", "data" : { "device": "ide-hd1",
"snapshot-file": "/some/place/my-image2",
"mode": "existing",