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HXCOMM QMP dispatch table and documentation

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SQMP

                        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 (QMP/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.

EQMP

    {

        .name       = "quit",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_quit,

    },

SQMP

quit

----

Quit the emulator.

Arguments: None.

Example:

-> { "execute": "quit" }

<- { "return": {} }

EQMP

    {

        .name       = "eject",

        .args_type  = "force:-f,device:B",

        .mhandler.cmd_new = qmp_marshal_input_eject,

    },

SQMP

eject

-----

Eject a removable medium.

Arguments: 

- force: force ejection (json-bool, optional)

- device: device name (json-string)

Example:

-> { "execute": "eject", "arguments": { "device": "ide1-cd0" } }

<- { "return": {} }

Note: The "force" argument defaults to false.

EQMP

    {

        .name       = "change",

        .args_type  = "device:B,target:F,arg:s?",

        .mhandler.cmd_new = qmp_marshal_input_change,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "screendump",

        .args_type  = "filename:F",

        .mhandler.cmd_new = qmp_marshal_input_screendump,

    },

SQMP

screendump

----------

Save screen into PPM image.

Arguments:

- "filename": file path (json-string)

Example:

-> { "execute": "screendump", "arguments": { "filename": "/tmp/image" } }

<- { "return": {} }

EQMP

    {

        .name       = "stop",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_stop,

    },

SQMP

stop

----

Stop the emulator.

Arguments: None.

Example:

-> { "execute": "stop" }

<- { "return": {} }

EQMP

    {

        .name       = "cont",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_cont,

    },

SQMP

cont

----

Resume emulation.

Arguments: None.

Example:

-> { "execute": "cont" }

<- { "return": {} }

EQMP

    {

        .name       = "system_wakeup",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_system_wakeup,

    },

SQMP

system_wakeup

-------------

Wakeup guest from suspend.

Arguments: None.

Example:

-> { "execute": "system_wakeup" }

<- { "return": {} }

EQMP

    {

        .name       = "system_reset",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_system_reset,

    },

SQMP

system_reset

------------

Reset the system.

Arguments: None.

Example:

-> { "execute": "system_reset" }

<- { "return": {} }

EQMP

    {

        .name       = "system_powerdown",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_system_powerdown,

    },

SQMP

system_powerdown

----------------

Send system power down event.

Arguments: None.

Example:

-> { "execute": "system_powerdown" }

<- { "return": {} }

EQMP

    {

        .name       = "device_add",

        .args_type  = "device:O",

        .params     = "driver[,prop=value][,...]",

        .help       = "add device, like -device on the command line",

        .user_print = monitor_user_noop,

        .mhandler.cmd_new = do_device_add,

    },

SQMP

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

EQMP

    {

        .name       = "device_del",

        .args_type  = "id:s",

        .mhandler.cmd_new = qmp_marshal_input_device_del,

    },

SQMP

device_del

----------

Remove a device.

Arguments:

- "id": the device's ID (json-string)

Example:

-> { "execute": "device_del", "arguments": { "id": "net1" } }

<- { "return": {} }

EQMP

    {

        .name       = "send-key",

        .args_type  = "keys:O,hold-time:i?",

        .mhandler.cmd_new = qmp_marshal_input_send_key,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "cpu",

        .args_type  = "index:i",

        .mhandler.cmd_new = qmp_marshal_input_cpu,

    },

SQMP

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.

EQMP

    {

        .name       = "cpu-add",

        .args_type  = "id:i",

        .mhandler.cmd_new = qmp_marshal_input_cpu_add,

    },

SQMP

cpu-add

-------

Adds virtual cpu

Arguments:

- "id": cpu id (json-int)

Example:

-> { "execute": "cpu-add", "arguments": { "id": 2 } }

<- { "return": {} }

EQMP

    {

        .name       = "memsave",

        .args_type  = "val:l,size:i,filename:s,cpu:i?",

        .mhandler.cmd_new = qmp_marshal_input_memsave,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "pmemsave",

        .args_type  = "val:l,size:i,filename:s",

        .mhandler.cmd_new = qmp_marshal_input_pmemsave,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "inject-nmi",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_inject_nmi,

    },

SQMP

inject-nmi

----------

Inject an NMI on guest's CPUs.

Arguments: None.

Example:

-> { "execute": "inject-nmi" }

<- { "return": {} }

Note: inject-nmi fails when the guest doesn't support injecting.

      Currently, only x86 (NMI) and s390x (RESTART) guests do.

EQMP

    {

        .name       = "ringbuf-write",

        .args_type  = "device:s,data:s,format:s?",

        .mhandler.cmd_new = qmp_marshal_input_ringbuf_write,

    },

SQMP

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"

            Bug: invalid base64 is currently not rejected.

            Whitespace *is* invalid.

Example:

-> { "execute": "ringbuf-write",

                "arguments": { "device": "foo",

                               "data": "abcdefgh",

                               "format": "utf8" } }

<- { "return": {} }

EQMP

    {

        .name       = "ringbuf-read",

        .args_type  = "device:s,size:i,format:s?",

        .mhandler.cmd_new = qmp_marshal_input_ringbuf_read,

    },

SQMP

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"}

EQMP

    {

        .name       = "xen-save-devices-state",

        .args_type  = "filename:F",

    .mhandler.cmd_new = qmp_marshal_input_xen_save_devices_state,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "xen-set-global-dirty-log",

        .args_type  = "enable:b",

        .mhandler.cmd_new = qmp_marshal_input_xen_set_global_dirty_log,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "migrate",

        .args_type  = "detach:-d,blk:-b,inc:-i,uri:s",

        .mhandler.cmd_new = qmp_marshal_input_migrate,

    },

SQMP

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

EQMP

    {

        .name       = "migrate_cancel",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_migrate_cancel,

    },

SQMP

migrate_cancel

--------------

Cancel the current migration.

Arguments: None.

Example:

-> { "execute": "migrate_cancel" }

<- { "return": {} }

EQMP

{

        .name       = "migrate-set-cache-size",

        .args_type  = "value:o",

        .mhandler.cmd_new = qmp_marshal_input_migrate_set_cache_size,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "query-migrate-cache-size",

        .args_type  = "",

        .mhandler.cmd_new = qmp_marshal_input_query_migrate_cache_size,

    },

SQMP

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 }

EQMP

    {

        .name       = "migrate_set_speed",

        .args_type  = "value:o",

        .mhandler.cmd_new = qmp_marshal_input_migrate_set_speed,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "migrate_set_downtime",

        .args_type  = "value:T",

        .mhandler.cmd_new = qmp_marshal_input_migrate_set_downtime,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "client_migrate_info",

        .args_type  = "protocol:s,hostname:s,port:i?,tls-port:i?,cert-subject:s?",

        .params     = "protocol hostname port tls-port cert-subject",

        .help       = "send migration info to spice/vnc client",

        .user_print = monitor_user_noop,

        .mhandler.cmd_async = client_migrate_info,

        .flags      = MONITOR_CMD_ASYNC,

    },

SQMP

client_migrate_info

------------------

Set the spice/vnc connection info for the migration target.  The spice/vnc

server will ask the spice/vnc client to automatically reconnect using the

new parameters (if specified) once the vm migration finished successfully.

Arguments:

- "protocol":     protocol: "spice" or "vnc" (json-string)

- "hostname":     migration target hostname (json-string)

- "port":         spice/vnc 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": {} }

EQMP

    {

        .name       = "dump-guest-memory",

        .args_type  = "paging:b,protocol:s,begin:i?,end:i?,format:s?",

        .params     = "-p protocol [begin] [length] [format]",

        .help       = "dump guest memory to file",

        .user_print = monitor_user_noop,

        .mhandler.cmd_new = qmp_marshal_input_dump_guest_memory,

    },

SQMP

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)

- "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

EQMP

    {

        .name       = "query-dump-guest-memory-capability",

        .args_type  = "",

    .mhandler.cmd_new = qmp_marshal_input_query_dump_guest_memory_capability,

    },

SQMP

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"] }

EQMP

    {

        .name       = "netdev_add",

        .args_type  = "netdev:O",

        .mhandler.cmd_new = qmp_netdev_add,

    },

SQMP

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" } }

<- { "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

EQMP

    {

        .name       = "netdev_del",

        .args_type  = "id:s",

        .mhandler.cmd_new = qmp_marshal_input_netdev_del,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "object-add",

        .args_type  = "qom-type:s,id:s,props:q?",

        .mhandler.cmd_new = qmp_object_add,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "object-del",

        .args_type  = "id:s",

        .mhandler.cmd_new = qmp_marshal_input_object_del,

    },

SQMP

object-del

----------

Remove QOM object.

Arguments:

- "id": the object's ID (json-string)

Example:

-> { "execute": "object-del", "arguments": { "id": "rng1" } }

<- { "return": {} }

EQMP

    {

        .name       = "block_resize",

        .args_type  = "device:s?,node-name:s?,size:o",

        .mhandler.cmd_new = qmp_marshal_input_block_resize,

    },

SQMP

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": {} }

EQMP

    {

        .name       = "block-stream",

        .args_type  = "device:B,base:s?,speed:o?,on-error:s?",

        .mhandler.cmd_new = qmp_marshal_input_block_stream,

    },

    {

        .name       = "block-commit",

        .args_type  = "device:B,base:s?,top:s,speed:o?",

        .mhandler.cmd_new = qmp_marshal_input_block_commit,

    },

SQMP

block-commit

------------

Live commit of data from overlay image nodes into backing nodes - i.e., writes

data between 'top' and 'base' into 'base'.

Arguments:

- "device": The device's ID, must be unique (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 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": {} }

EQMP

    {

        .name       = "drive-backup",

        .args_type  = "sync:s,device:B,target:s,speed:i?,mode:s?,format:s?,"

                      "on-source-error:s?,on-target-error:s?",

        .mhandler.cmd_new = qmp_marshal_input_drive_backup,

    },

SQMP

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:

- "device": the name of the device 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, or "none" to only replicate new I/O

  (MirrorSyncMode).

- "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)

- "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": {} }

EQMP

    {

        .name       = "block-job-set-speed",

        .args_type  = "device:B,speed:o",

        .mhandler.cmd_new = qmp_marshal_input_block_job_set_speed,

    },

    {

        .name       = "block-job-cancel",

        .args_type  = "device:B,force:b?",

        .mhandler.cmd_new = qmp_marshal_input_block_job_cancel,

    },

    {

        .name       = "block-job-pause",

        .args_type  = "device:B",

        .mhandler.cmd_new = qmp_marshal_input_block_job_pause,

    },

    {

        .name       = "block-job-resume",

        .args_type  = "device:B",

        .mhandler.cmd_new = qmp_marshal_input_block_job_resume,

    },

    {

        .name       = "block-job-complete",

        .args_type  = "device:B",

        .mhandler.cmd_new = qmp_marshal_input_block_job_complete,

    },

    {

        .name       = "transaction",

        .args_type  = "actions:q",

        .mhandler.cmd_new = qmp_marshal_input_transaction,

    },

SQMP

transaction

-----------

Atomically operate on one or more block devices.  The only supported operations

for now are drive-backup, internal and external snapshotting.  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.  The only supported

      value is "blockdev-snapshot-sync". (json-string)

    - "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": device name 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",

                                         "format": "qcow2" } },

         { 'type': 'blockdev-snapshot-internal-sync', 'data' : {

                                         "device": "ide-hd2",

                                         "name": "snapshot0" } } ] } }

<- { "return": {} }

EQMP

    {

        .name       = "blockdev-snapshot-sync",

        .args_type  = "device:s?,node-name:s?,snapshot-file:s,snapshot-node-name:s?,format:s?,mode:s?",

        .mhandler.cmd_new = qmp_marshal_input_blockdev_snapshot_sync,

    },

SQMP

blockdev-snapshot-sync

----------------------

Synchronous snapshot of a block device. snapshot-file specifies the

target of the new image. If the file exists, or if it is a device, the

snapshot will be created in the existing file/device. If does not

exist, a new file will be created. format specifies the format of the

snapshot image, default is qcow2.

Arguments:

- "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)

- "mode": whether and how QEMU should create the snapshot file

  (NewImageMode, optional, default "absolute-paths")

- "format": format of new image (json-string, optional)

Example:

-> { "execute": "blockdev-snapshot-sync", "arguments": { "device": "ide-hd0",

                                                         "snapshot-file":

                                                        "/some/place/my-image",

                                                        "format": "qcow2" } }

<- { "return": {} }

EQMP

    {

        .name       = "blockdev-snapshot-internal-sync",

        .args_type  = "device:B,name:s",

        .mhandler.cmd_new = qmp_marshal_input_blockdev_snapshot_internal_sync,

    },

SQMP

blockdev-snapshot-internal-sync

-------------------------------

Synchronously take an internal snapshot of a block device when the format of

image used supports it.  If the name is an empty string, or a snapshot with

name already exists, the operation will fail.

Arguments:

- "device": device name to snapshot (json-string)

- "name": name of the new snapshot (json-string)

Example:

-> { "execute": "blockdev-snapshot-internal-sync",

                "arguments": { "device": "ide-hd0",

                               "name": "snapshot0" }

   }

<- { "return": {} }

EQMP

    {

        .name       = "blockdev-snapshot-delete-internal-sync",

        .args_type  = "device:B,id:s?,name:s?",

        .mhandler.cmd_new =

                      qmp_marshal_input_blockdev_snapshot_delete_internal_sync,

    },

SQMP

blockdev-snapshot-delete-internal-sync

--------------------------------------

Synchronously delete an internal snapshot of a block device when the format of

image used supports it.  The snapshot is identified by name or id or both.  One

of name or id is required.  If the snapshot is not found, the operation will

fail.

Arguments:

- "device": device name (json-string)

- "id": ID of the snapshot (json-string, optional)

- "name": name of the snapshot (json-string, optional)

Example:

-> { "execute": "blockdev-snapshot-delete-internal-sync",

                "arguments": { "device": "ide-hd0",

                               "name": "snapshot0" }

   }

<- { "return": {

                   "id": "1",

                   "name": "snapshot0",

                   "vm-state-size": 0,

                   "date-sec": 1000012,

                   "date-nsec": 10,

                   "vm-clock-sec": 100,

                   "vm-clock-nsec": 20

     }

   }

EQMP

    {

        .name       = "drive-mirror",

        .args_type  = "sync:s,device:B,target:s,speed:i?,mode:s?,format:s?,"

                      "on-source-error:s?,on-target-error:s?,"

                      "granularity:i?,buf-size:i?",

        .mhandler.cmd_new = qmp_marshal_input_drive_mirror,

    },

SQMP

drive-mirror

------------

Start mirroring a block device's writes to a new destination. target

specifies the target of the new image. If the file exists, or if it is

a device, it will be used as the new destination for writes. If it does not

exist, a new file will be created. format specifies the format of the

mirror image, default is to probe if mode='existing', else the format

of the source.

Arguments:

- "device": device name to operate on (json-string)

- "target": name of new image file (json-string)

- "format": format of new image (json-string, optional)

- "mode": how an image file should be created into the target

  file/device (NewImageMode, optional, default 'absolute-paths')

- "speed": maximum speed of the streaming job, in bytes per second

  (json-int)

- "granularity": granularity of the dirty bitmap, in bytes (json-int, optional)

- "buf_size": maximum amount of data in flight from source to target, in bytes

  (json-int, default 10M)

- "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).

- "on-source-error": the action to take on an error on the source

  (BlockdevOnError, default 'report')

- "on-target-error": the action to take on an error on the target

  (BlockdevOnError, default 'report')

The default value of the granularity is the image cluster size clamped

between 4096 and 65536, if the image format defines one.  If the format

does not define a cluster size, the default value of the granularity

is 65536.

Example:

-> { "execute": "drive-mirror", "arguments": { "device": "ide-hd0",

                                               "target": "/some/place/my-image",

                                               "sync": "full",

                                               "format": "qcow2" } }

<- { "return": {} }

EQMP

    {

        .name       = "balloon",

        .args_type  = "value:M",

        .mhandler.cmd_new = qmp_marshal_input_balloon,

    },

SQMP

balloon

-------

Request VM to change its memory allocation (in bytes).

Arguments:

- "value": New memory allocation (json-int)

Example:

-> { "execute": "balloon", "arguments": { "value": 536870912 } }

<- { "return": {} }

EQMP

    {

        .name       = "set_link",

        .args_type  = "name:s,up:b",

        .mhandler.cmd_new = qmp_marshal_input_set_link,

    },

SQMP

set_link

--------

Change the link status of a network adapter.

Arguments:

- "name": network device name (json-string)

- "up": status is up (json-bool)

Example:

-> { "execute": "set_link", "arguments": { "name": "e1000.0", "up": false } }

<- { "return": {} }

EQMP

    {

        .name       = "getfd",

        .args_type  = "fdname:s",

        .params     = "getfd name",

        .help       = "receive a file descriptor via SCM rights and assign it a name",

        .mhandler.cmd_new = qmp_marshal_input_getfd,

    },

SQMP

getfd

-----

Receive a file descriptor via SCM rights and assign it a name.

Arguments:

- "fdname": file descriptor name (json-string)

Example:

-> { "execute": "getfd", "arguments": { "fdname": "fd1" } }

<- { "return": {} }

Notes:

(1) If the name specified by the "fdname" argument already exists,

    the file descriptor assigned to it will be closed and replaced

    by the received file descriptor.

(2) The 'closefd' command can be used to explicitly close the file

    descriptor when it is no longer needed.

EQMP

    {

        .name       = "closefd",

        .args_type  = "fdname:s",

        .params     = "closefd name",

        .help       = "close a file descriptor previously passed via SCM rights",

        .mhandler.cmd_new = qmp_marshal_input_closefd,

    },

SQMP

closefd

-------

Close a file descriptor previously passed via SCM rights.

Arguments:

- "fdname": file descriptor name (json-string)

Example:

-> { "execute": "closefd", "arguments": { "fdname": "fd1" } }

<- { "return": {} }

EQMP

     {

        .name       = "add-fd",

        .args_type  = "fdset-id:i?,opaque:s?",

        .params     = "add-fd fdset-id opaque",

        .help       = "Add a file descriptor, that was passed via SCM rights, to an fd set",

        .mhandler.cmd_new = qmp_marshal_input_add_fd,

    },

SQMP

add-fd

-------

Add a file descriptor, that was passed via SCM rights, to an fd set.

Arguments:

- "fdset-id": The ID of the fd set to add the file descriptor to.

              (json-int, optional)

- "opaque": A free-form string that can be used to describe the fd.

            (json-string, optional)

Return a json-object with the following information:

- "fdset-id": The ID of the fd set that the fd was added to. (json-int)

- "fd": The file descriptor that was received via SCM rights and added to the

        fd set. (json-int)

Example:

-> { "execute": "add-fd", "arguments": { "fdset-id": 1 } }

<- { "return": { "fdset-id": 1, "fd": 3 } }

Notes:

(1) The list of fd sets is shared by all monitor connections.

(2) If "fdset-id" is not specified, a new fd set will be created.

EQMP

     {

        .name       = "remove-fd",

        .args_type  = "fdset-id:i,fd:i?",

        .params     = "remove-fd fdset-id fd",

        .help       = "Remove a file descriptor from an fd set",

        .mhandler.cmd_new = qmp_marshal_input_remove_fd,

    },

SQMP

remove-fd

---------

Remove a file descriptor from an fd set.

Arguments:

- "fdset-id": The ID of the fd set that the file descriptor belongs to.

              (json-int)

- "fd": The file descriptor that is to be removed. (json-int, optional)

Example:

-> { "execute": "remove-fd", "arguments": { "fdset-id": 1, "fd": 3 } }

<- { "return": {} }

Notes:

(1) The list of fd sets is shared by all monitor connections.

(2) If "fd" is not specified, all file descriptors in "fdset-id" will be

    removed.

EQMP

    {

        .name       = "query-fdsets",

        .args_type  = "",

        .help       = "Return information describing all fd sets",

        .mhandler.cmd_new = qmp_marshal_input_query_fdsets,

    },

SQMP

query-fdsets

-------------

Return information describing all fd sets.

Arguments: None

Example:

-> { "execute": "query-fdsets" }

<- { "return": [

       {

         "fds": [

           {

             "fd": 30,

             "opaque": "rdonly:/path/to/file"

           },

           {

             "fd": 24,

             "opaque": "rdwr:/path/to/file"

           }

         ],

         "fdset-id": 1

       },

       {

         "fds": [

           {

             "fd": 28

           },

           {

             "fd": 29

           }

         ],

         "fdset-id": 0

       }

     ]

   }

Note: The list of fd sets is shared by all monitor connections.

EQMP

    {

        .name       = "block_passwd",

        .args_type  = "device:s?,node-name:s?,password:s",

        .mhandler.cmd_new = qmp_marshal_input_block_passwd,

    },

SQMP

block_passwd

------------

Set the password of encrypted block devices.