QEMU-STORAGE-DAEMON-QMP-REF(7) QEMU QEMU-STORAGE-DAEMON-QMP-REF(7)

qemu-storage-daemon-qmp-ref - QEMU Storage Daemon QMP Reference Manual

•
QEMU Storage Daemon QMP Reference Manual
•
Common data types
  • IoOperationType (Enum)
  • OnOffAuto (Enum)
  • OnOffSplit (Enum)
  • String (Object)
  • StrOrNull (Alternate)
  • OffAutoPCIBAR (Enum)
  • PCIELinkSpeed (Enum)
  • PCIELinkWidth (Enum)
  • HostMemPolicy (Enum)
  • NetFilterDirection (Enum)
  • GrabToggleKeys (Enum)
  • HumanReadableText (Object)
•
Socket data types
  • NetworkAddressFamily (Enum)
  • InetSocketAddressBase (Object)
  • InetSocketAddress (Object)
  • UnixSocketAddress (Object)
  • VsockSocketAddress (Object)
  • InetSocketAddressWrapper (Object)
  • UnixSocketAddressWrapper (Object)
  • VsockSocketAddressWrapper (Object)
  • StringWrapper (Object)
  • SocketAddressLegacy (Object)
  • SocketAddressType (Enum)
  • SocketAddress (Object)
•
Cryptography
  • QCryptoTLSCredsEndpoint (Enum)
  • QCryptoSecretFormat (Enum)
  • QCryptoHashAlgorithm (Enum)
  • QCryptoCipherAlgorithm (Enum)
  • QCryptoCipherMode (Enum)
  • QCryptoIVGenAlgorithm (Enum)
  • QCryptoBlockFormat (Enum)
  • QCryptoBlockOptionsBase (Object)
  • QCryptoBlockOptionsQCow (Object)
  • QCryptoBlockOptionsLUKS (Object)
  • QCryptoBlockCreateOptionsLUKS (Object)
  • QCryptoBlockOpenOptions (Object)
  • QCryptoBlockCreateOptions (Object)
  • QCryptoBlockInfoBase (Object)
  • QCryptoBlockInfoLUKSSlot (Object)
  • QCryptoBlockInfoLUKS (Object)
  • QCryptoBlockInfo (Object)
  • QCryptoBlockLUKSKeyslotState (Enum)
  • QCryptoBlockAmendOptionsLUKS (Object)
  • QCryptoBlockAmendOptions (Object)
  • SecretCommonProperties (Object)
  • SecretProperties (Object)
  • SecretKeyringProperties (Object)
  • TlsCredsProperties (Object)
  • TlsCredsAnonProperties (Object)
  • TlsCredsPskProperties (Object)
  • TlsCredsX509Properties (Object)
  • QCryptoAkCipherAlgorithm (Enum)
  • QCryptoAkCipherKeyType (Enum)
  • QCryptoRSAPaddingAlgorithm (Enum)
  • QCryptoAkCipherOptionsRSA (Object)
  • QCryptoAkCipherOptions (Object)
•
Background jobs
  • JobType (Enum)
  • JobStatus (Enum)
  • JobVerb (Enum)
  • JOB_STATUS_CHANGE (Event)
  • job-pause (Command)
  • job-resume (Command)
  • job-cancel (Command)
  • job-complete (Command)
  • job-dismiss (Command)
  • job-finalize (Command)
  • JobInfo (Object)
  • query-jobs (Command)
•
Block devices
  • Block core (VM unrelated)
  • Block device exports
•
Character devices
  • ChardevInfo (Object)
  • query-chardev (Command)
  • ChardevBackendInfo (Object)
  • query-chardev-backends (Command)
  • DataFormat (Enum)
  • ringbuf-write (Command)
  • ringbuf-read (Command)
  • ChardevCommon (Object)
  • ChardevFile (Object)
  • ChardevHostdev (Object)
  • ChardevSocket (Object)
  • ChardevUdp (Object)
  • ChardevMux (Object)
  • ChardevStdio (Object)
  • ChardevSpiceChannel (Object)
  • ChardevSpicePort (Object)
  • ChardevDBus (Object)
  • ChardevVC (Object)
  • ChardevRingbuf (Object)
  • ChardevQemuVDAgent (Object)
  • ChardevBackendKind (Enum)
  • ChardevFileWrapper (Object)
  • ChardevHostdevWrapper (Object)
  • ChardevSocketWrapper (Object)
  • ChardevUdpWrapper (Object)
  • ChardevCommonWrapper (Object)
  • ChardevMuxWrapper (Object)
  • ChardevStdioWrapper (Object)
  • ChardevSpiceChannelWrapper (Object)
  • ChardevSpicePortWrapper (Object)
  • ChardevQemuVDAgentWrapper (Object)
  • ChardevDBusWrapper (Object)
  • ChardevVCWrapper (Object)
  • ChardevRingbufWrapper (Object)
  • ChardevBackend (Object)
  • ChardevReturn (Object)
  • chardev-add (Command)
  • chardev-change (Command)
  • chardev-remove (Command)
  • chardev-send-break (Command)
  • VSERPORT_CHANGE (Event)
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User authorization
  • QAuthZListPolicy (Enum)
  • QAuthZListFormat (Enum)
  • QAuthZListRule (Object)
  • AuthZListProperties (Object)
  • AuthZListFileProperties (Object)
  • AuthZPAMProperties (Object)
  • AuthZSimpleProperties (Object)
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Transactions
  • Abort (Object)
  • ActionCompletionMode (Enum)
  • TransactionActionKind (Enum)
  • AbortWrapper (Object)
  • BlockDirtyBitmapAddWrapper (Object)
  • BlockDirtyBitmapWrapper (Object)
  • BlockDirtyBitmapMergeWrapper (Object)
  • BlockdevBackupWrapper (Object)
  • BlockdevSnapshotWrapper (Object)
  • BlockdevSnapshotInternalWrapper (Object)
  • BlockdevSnapshotSyncWrapper (Object)
  • DriveBackupWrapper (Object)
  • TransactionAction (Object)
  • TransactionProperties (Object)
  • transaction (Command)
•
QMP monitor control
  • qmp_capabilities (Command)
  • QMPCapability (Enum)
  • VersionTriple (Object)
  • VersionInfo (Object)
  • query-version (Command)
  • CommandInfo (Object)
  • query-commands (Command)
  • quit (Command)
  • MonitorMode (Enum)
  • MonitorOptions (Object)
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QMP introspection
  • query-qmp-schema (Command)
  • SchemaMetaType (Enum)
  • SchemaInfo (Object)
  • SchemaInfoBuiltin (Object)
  • JSONType (Enum)
  • SchemaInfoEnum (Object)
  • SchemaInfoEnumMember (Object)
  • SchemaInfoArray (Object)
  • SchemaInfoObject (Object)
  • SchemaInfoObjectMember (Object)
  • SchemaInfoObjectVariant (Object)
  • SchemaInfoAlternate (Object)
  • SchemaInfoAlternateMember (Object)
  • SchemaInfoCommand (Object)
  • SchemaInfoEvent (Object)
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QEMU Object Model (QOM)
  • ObjectPropertyInfo (Object)
  • qom-list (Command)
  • qom-get (Command)
  • qom-set (Command)
  • ObjectTypeInfo (Object)
  • qom-list-types (Command)
  • qom-list-properties (Command)
  • CanHostSocketcanProperties (Object)
  • ColoCompareProperties (Object)
  • CryptodevBackendProperties (Object)
  • CryptodevVhostUserProperties (Object)
  • DBusVMStateProperties (Object)
  • NetfilterInsert (Enum)
  • NetfilterProperties (Object)
  • FilterBufferProperties (Object)
  • FilterDumpProperties (Object)
  • FilterMirrorProperties (Object)
  • FilterRedirectorProperties (Object)
  • FilterRewriterProperties (Object)
  • InputBarrierProperties (Object)
  • InputLinuxProperties (Object)
  • EventLoopBaseProperties (Object)
  • IothreadProperties (Object)
  • MainLoopProperties (Object)
  • MemoryBackendProperties (Object)
  • MemoryBackendFileProperties (Object)
  • MemoryBackendMemfdProperties (Object)
  • MemoryBackendEpcProperties (Object)
  • PrManagerHelperProperties (Object)
  • QtestProperties (Object)
  • RemoteObjectProperties (Object)
  • VfioUserServerProperties (Object)
  • RngProperties (Object)
  • RngEgdProperties (Object)
  • RngRandomProperties (Object)
  • SevGuestProperties (Object)
  • ThreadContextProperties (Object)
  • ObjectType (Enum)
  • ObjectOptions (Object)
  • object-add (Command)
  • object-del (Command)

IoOperationType (Enum)

An enumeration of the I/O operation types

read operation
write operation

2.1

OnOffAuto (Enum)

An enumeration of three options: on, off, and auto

QEMU selects the value between on and off
Enabled
Disabled

2.2

OnOffSplit (Enum)

An enumeration of three values: on, off, and split

Enabled
Disabled
Mixed

2.6

String (Object)

A fat type wrapping 'str', to be embedded in lists.

Not documented

1.2

StrOrNull (Alternate)

This is a string value or the explicit lack of a string (null pointer in C). Intended for cases when 'optional absent' already has a different meaning.

the string value
no string value

2.10

OffAutoPCIBAR (Enum)

An enumeration of options for specifying a PCI BAR

The specified feature is disabled
The PCI BAR for the feature is automatically selected
PCI BAR0 is used for the feature
PCI BAR1 is used for the feature
PCI BAR2 is used for the feature
PCI BAR3 is used for the feature
PCI BAR4 is used for the feature
PCI BAR5 is used for the feature

2.12

PCIELinkSpeed (Enum)

An enumeration of PCIe link speeds in units of GT/s

2_5
2.5GT/s
5
5.0GT/s
8
8.0GT/s
16
16.0GT/s

4.0

PCIELinkWidth (Enum)

An enumeration of PCIe link width

1
x1
2
x2
4
x4
8
x8
12
x12
16
x16
32
x32

4.0

HostMemPolicy (Enum)

Host memory policy types

restore default policy, remove any nondefault policy
set the preferred host nodes for allocation
a strict policy that restricts memory allocation to the host nodes specified
memory allocations are interleaved across the set of host nodes specified

2.1

NetFilterDirection (Enum)

Indicates whether a netfilter is attached to a netdev's transmit queue or receive queue or both.

the filter is attached both to the receive and the transmit queue of the netdev (default).
the filter is attached to the receive queue of the netdev, where it will receive packets sent to the netdev.
the filter is attached to the transmit queue of the netdev, where it will receive packets sent by the netdev.

2.5

GrabToggleKeys (Enum)

Keys to toggle input-linux between host and guest.

Not documented
Not documented
Not documented
Not documented
Not documented
Not documented

4.0

HumanReadableText (Object)

Formatted output intended for humans.

6.2

NetworkAddressFamily (Enum)

The network address family

IPV4 family
IPV6 family
unix socket
vsock family (since 2.8)
otherwise

2.1

InetSocketAddressBase (Object)

host part of the address
port part of the address

InetSocketAddress (Object)

Captures a socket address or address range in the Internet namespace.

true if the host/port are guaranteed to be numeric, false if name resolution should be attempted. Defaults to false. (Since 2.9)
If present, this is range of possible addresses, with port between port and to.
whether to accept IPv4 addresses, default try both IPv4 and IPv6
whether to accept IPv6 addresses, default try both IPv4 and IPv6
enable keep-alive when connecting to this socket. Not supported for passive sockets. (Since 4.2)
enable multi-path TCP. (Since 6.1)

1.3

UnixSocketAddress (Object)

Captures a socket address in the local ("Unix socket") namespace.

filesystem path to use
if true, this is a Linux abstract socket address. path will be prefixed by a null byte, and optionally padded with null bytes. Defaults to false. (Since 5.1)
if false, pad an abstract socket address with enough null bytes to make it fill struct sockaddr_un member sun_path. Defaults to true. (Since 5.1)

1.3

VsockSocketAddress (Object)

Captures a socket address in the vsock namespace.

unique host identifier
port

string types are used to allow for possible future hostname or service resolution support.

2.8

InetSocketAddressWrapper (Object)

Not documented

1.3

UnixSocketAddressWrapper (Object)

Not documented

1.3

VsockSocketAddressWrapper (Object)

Not documented

2.8

StringWrapper (Object)

Not documented

1.3

SocketAddressLegacy (Object)

Captures the address of a socket, which could also be a named file descriptor

Not documented

This type is deprecated in favor of SocketAddress. The difference between SocketAddressLegacy and SocketAddress is that the latter has fewer {} on the wire.

1.3

SocketAddressType (Enum)

Available SocketAddress types

Internet address
Unix domain socket
VMCI address
decimal is for file descriptor number, otherwise a file descriptor name. Named file descriptors are permitted in monitor commands, in combination with the 'getfd' command. Decimal file descriptors are permitted at startup or other contexts where no monitor context is active.

2.9

SocketAddress (Object)

Captures the address of a socket, which could also be a named file descriptor

Transport type

2.9

QCryptoTLSCredsEndpoint (Enum)

The type of network endpoint that will be using the credentials. Most types of credential require different setup / structures depending on whether they will be used in a server versus a client.

the network endpoint is acting as the client
the network endpoint is acting as the server

2.5

QCryptoSecretFormat (Enum)

The data format that the secret is provided in

raw bytes. When encoded in JSON only valid UTF-8 sequences can be used
arbitrary base64 encoded binary data

2.6

QCryptoHashAlgorithm (Enum)

The supported algorithms for computing content digests

MD5. Should not be used in any new code, legacy compat only
SHA-1. Should not be used in any new code, legacy compat only
SHA-224. (since 2.7)
SHA-256. Current recommended strong hash.
SHA-384. (since 2.7)
SHA-512. (since 2.7)
RIPEMD-160. (since 2.7)

2.6

QCryptoCipherAlgorithm (Enum)

The supported algorithms for content encryption ciphers

AES with 128 bit / 16 byte keys
AES with 192 bit / 24 byte keys
AES with 256 bit / 32 byte keys
DES with 56 bit / 8 byte keys. Do not use except in VNC. (since 6.1)
3des
3DES(EDE) with 192 bit / 24 byte keys (since 2.9)
Cast5 with 128 bit / 16 byte keys
Serpent with 128 bit / 16 byte keys
Serpent with 192 bit / 24 byte keys
Serpent with 256 bit / 32 byte keys
Twofish with 128 bit / 16 byte keys
Twofish with 192 bit / 24 byte keys
Twofish with 256 bit / 32 byte keys

2.6

QCryptoCipherMode (Enum)

The supported modes for content encryption ciphers

Electronic Code Book
Cipher Block Chaining
XEX with tweaked code book and ciphertext stealing
Counter (Since 2.8)

2.6

QCryptoIVGenAlgorithm (Enum)

The supported algorithms for generating initialization vectors for full disk encryption. The 'plain' generator should not be used for disks with sector numbers larger than 2^32, except where compatibility with pre-existing Linux dm-crypt volumes is required.

64-bit sector number truncated to 32-bits
64-bit sector number
64-bit sector number encrypted with a hash of the encryption key

2.6

QCryptoBlockFormat (Enum)

The supported full disk encryption formats

QCow/QCow2 built-in AES-CBC encryption. Use only for liberating data from old images.
LUKS encryption format. Recommended for new images

2.6

QCryptoBlockOptionsBase (Object)

The common options that apply to all full disk encryption formats

the encryption format

2.6

QCryptoBlockOptionsQCow (Object)

The options that apply to QCow/QCow2 AES-CBC encryption format

the ID of a QCryptoSecret object providing the decryption key. Mandatory except when probing image for metadata only.

2.6

QCryptoBlockOptionsLUKS (Object)

The options that apply to LUKS encryption format

the ID of a QCryptoSecret object providing the decryption key. Mandatory except when probing image for metadata only.

2.6

QCryptoBlockCreateOptionsLUKS (Object)

The options that apply to LUKS encryption format initialization

the cipher algorithm for data encryption Currently defaults to 'aes-256'.
the cipher mode for data encryption Currently defaults to 'xts'
the initialization vector generator Currently defaults to 'plain64'
the initialization vector generator hash Currently defaults to 'sha256'
the master key hash algorithm Currently defaults to 'sha256'
number of milliseconds to spend in PBKDF passphrase processing. Currently defaults to 2000. (since 2.8)

2.6

QCryptoBlockOpenOptions (Object)

The options that are available for all encryption formats when opening an existing volume

2.6

QCryptoBlockCreateOptions (Object)

The options that are available for all encryption formats when initializing a new volume

2.6

QCryptoBlockInfoBase (Object)

The common information that applies to all full disk encryption formats

the encryption format

2.7

QCryptoBlockInfoLUKSSlot (Object)

Information about the LUKS block encryption key slot options

whether the key slot is currently in use
offset to the key material in bytes
number of PBKDF2 iterations for key material
number of stripes for splitting key material

2.7

QCryptoBlockInfoLUKS (Object)

Information about the LUKS block encryption options

the cipher algorithm for data encryption
the cipher mode for data encryption
the initialization vector generator
the initialization vector generator hash
the master key hash algorithm
offset to the payload data in bytes
number of PBKDF2 iterations for key material
unique identifier for the volume
information about each key slot

2.7

QCryptoBlockInfo (Object)

Information about the block encryption options

2.7

QCryptoBlockLUKSKeyslotState (Enum)

Defines state of keyslots that are affected by the update

The slots contain the given password and marked as active
The slots are erased (contain garbage) and marked as inactive

5.1

QCryptoBlockAmendOptionsLUKS (Object)

This struct defines the update parameters that activate/de-activate set of keyslots

the desired state of the keyslots
The ID of a QCryptoSecret object providing the password to be written into added active keyslots
Optional (for deactivation only) If given will deactivate all keyslots that match password located in QCryptoSecret with this ID
Optional (for activation only) Number of milliseconds to spend in PBKDF passphrase processing for the newly activated keyslot. Currently defaults to 2000.
Optional. ID of the keyslot to activate/deactivate. For keyslot activation, keyslot should not be active already (this is unsafe to update an active keyslot), but possible if 'force' parameter is given. If keyslot is not given, first free keyslot will be written.

For keyslot deactivation, this parameter specifies the exact keyslot to deactivate

Optional. The ID of a QCryptoSecret object providing the password to use to retrieve current master key. Defaults to the same secret that was used to open the image

5.1

QCryptoBlockAmendOptions (Object)

The options that are available for all encryption formats when amending encryption settings

5.1

SecretCommonProperties (Object)

Properties for objects of classes derived from secret-common.

if true, the secret is loaded immediately when applying this option and will probably fail when processing the next option. Don't use; only provided for compatibility. (default: false)
the data format that the secret is provided in (default: raw)
the name of another secret that should be used to decrypt the provided data. If not present, the data is assumed to be unencrypted.
the random initialization vector used for encryption of this particular secret. Should be a base64 encrypted string of the 16-byte IV. Mandatory if keyid is given. Ignored if keyid is absent.

Member loaded is deprecated. Setting true doesn't make sense, and false is already the default.

2.6

SecretProperties (Object)

Properties for secret objects.

Either data or file must be provided, but not both.

the associated with the secret from
the filename to load the data associated with the secret from

2.6

SecretKeyringProperties (Object)

Properties for secret_keyring objects.

serial number that identifies a key to get from the kernel

5.1

TlsCredsProperties (Object)

Properties for objects of classes derived from tls-creds.

if true the peer credentials will be verified once the handshake is completed. This is a no-op for anonymous credentials. (default: true)
the path of the directory that contains the credential files
whether the QEMU network backend that uses the credentials will be acting as a client or as a server (default: client)
a gnutls priority string as described at https://gnutls.org/manual/html_node/Priority-Strings.html

2.5

TlsCredsAnonProperties (Object)

Properties for tls-creds-anon objects.

if true, the credentials are loaded immediately when applying this option and will ignore options that are processed later. Don't use; only provided for compatibility. (default: false)

Member loaded is deprecated. Setting true doesn't make sense, and false is already the default.

2.5

TlsCredsPskProperties (Object)

Properties for tls-creds-psk objects.

if true, the credentials are loaded immediately when applying this option and will ignore options that are processed later. Don't use; only provided for compatibility. (default: false)
the username which will be sent to the server. For clients only. If absent, "qemu" is sent and the property will read back as an empty string.

Member loaded is deprecated. Setting true doesn't make sense, and false is already the default.

3.0

TlsCredsX509Properties (Object)

Properties for tls-creds-x509 objects.

if true, the credentials are loaded immediately when applying this option and will ignore options that are processed later. Don't use; only provided for compatibility. (default: false)
if true, perform some sanity checks before using the credentials (default: true)
For the server-key.pem and client-key.pem files which contain sensitive private keys, it is possible to use an encrypted version by providing the passwordid parameter. This provides the ID of a previously created secret object containing the password for decryption.

Member loaded is deprecated. Setting true doesn't make sense, and false is already the default.

2.5

QCryptoAkCipherAlgorithm (Enum)

The supported algorithms for asymmetric encryption ciphers

RSA algorithm

7.1

QCryptoAkCipherKeyType (Enum)

The type of asymmetric keys.

Not documented
Not documented

7.1

QCryptoRSAPaddingAlgorithm (Enum)

The padding algorithm for RSA.

no padding used
pkcs1#v1.5

7.1

QCryptoAkCipherOptionsRSA (Object)

Specific parameters for RSA algorithm.

QCryptoHashAlgorithm
QCryptoRSAPaddingAlgorithm

7.1

QCryptoAkCipherOptions (Object)

The options that are available for all asymmetric key algorithms when creating a new QCryptoAkCipher.

Not documented

7.1

JobType (Enum)

Type of a background job.

block commit job type, see "block-commit"
block stream job type, see "block-stream"
drive mirror job type, see "drive-mirror"
drive backup job type, see "drive-backup"
image creation job type, see "blockdev-create" (since 3.0)
image options amend job type, see "x-blockdev-amend" (since 5.1)
snapshot load job type, see "snapshot-load" (since 6.0)
snapshot save job type, see "snapshot-save" (since 6.0)
snapshot delete job type, see "snapshot-delete" (since 6.0)

1.7

JobStatus (Enum)

Indicates the present state of a given job in its lifetime.

Erroneous, default state. Should not ever be visible.
The job has been created, but not yet started.
The job is currently running.
The job is running, but paused. The pause may be requested by either the QMP user or by internal processes.
The job is running, but is ready for the user to signal completion. This is used for long-running jobs like mirror that are designed to run indefinitely.
The job is ready, but paused. This is nearly identical to paused. The job may return to ready or otherwise be canceled.
The job is waiting for other jobs in the transaction to converge to the waiting state. This status will likely not be visible for the last job in a transaction.
The job has finished its work, but has finalization steps that it needs to make prior to completing. These changes will require manual intervention via job-finalize if auto-finalize was set to false. These pending changes may still fail.
The job is in the process of being aborted, and will finish with an error. The job will afterwards report that it is concluded. This status may not be visible to the management process.
The job has finished all work. If auto-dismiss was set to false, the job will remain in the query list until it is dismissed via job-dismiss.
The job is in the process of being dismantled. This state should not ever be visible externally.

2.12

JobVerb (Enum)

Represents command verbs that can be applied to a job.

see job-cancel
see job-pause
see job-resume
see block-job-set-speed
see job-complete
see job-dismiss
see job-finalize
see block-job-change (since 8.2)

2.12

JOB_STATUS_CHANGE (Event)

Emitted when a job transitions to a different status.

The job identifier
The new job status

3.0

job-pause (Command)

Pause an active job.

This command returns immediately after marking the active job for pausing. Pausing an already paused job is an error.

The job will pause as soon as possible, which means transitioning into the PAUSED state if it was RUNNING, or into STANDBY if it was READY. The corresponding JOB_STATUS_CHANGE event will be emitted.

Cancelling a paused job automatically resumes it.

The job identifier.

3.0

job-resume (Command)

Resume a paused job.

This command returns immediately after resuming a paused job. Resuming an already running job is an error.

The job identifier.

3.0

job-cancel (Command)

Instruct an active background job to cancel at the next opportunity. This command returns immediately after marking the active job for cancellation.

The job will cancel as soon as possible and then emit a JOB_STATUS_CHANGE event. Usually, the status will change to ABORTING, but it is possible that a job successfully completes (e.g. because it was almost done and there was no opportunity to cancel earlier than completing the job) and transitions to PENDING instead.

The job identifier.

3.0

job-complete (Command)

Manually trigger completion of an active job in the READY state.

The job identifier.

3.0

job-dismiss (Command)

Deletes a job that is in the CONCLUDED state. This command only needs to be run explicitly for jobs that don't have automatic dismiss enabled.

This command will refuse to operate on any job that has not yet reached its terminal state, JOB_STATUS_CONCLUDED. For jobs that make use of JOB_READY event, job-cancel or job-complete will still need to be used as appropriate.

The job identifier.

3.0

job-finalize (Command)

Instructs all jobs in a transaction (or a single job if it is not part of any transaction) to finalize any graph changes and do any necessary cleanup. This command requires that all involved jobs are in the PENDING state.

For jobs in a transaction, instructing one job to finalize will force ALL jobs in the transaction to finalize, so it is only necessary to instruct a single member job to finalize.

The identifier of any job in the transaction, or of a job that is not part of any transaction.

3.0

JobInfo (Object)

Information about a job.

The job identifier
The kind of job that is being performed
Current job state/status
Progress made until now. The unit is arbitrary and the value can only meaningfully be used for the ratio of current-progress to total-progress. The value is monotonically increasing.
Estimated current-progress value at the completion of the job. This value can arbitrarily change while the job is running, in both directions.
If this field is present, the job failed; if it is still missing in the CONCLUDED state, this indicates successful completion.

The value is a human-readable error message to describe the reason for the job failure. It should not be parsed by applications.

3.0

query-jobs (Command)

Return information about jobs.

a list with a JobInfo for each active job

3.0

SnapshotInfo (Object)

unique snapshot id
user chosen name
size of the VM state
UTC date of the snapshot in seconds
fractional part in nano seconds to be used with date-sec
VM clock relative to boot in seconds
fractional part in nano seconds to be used with vm-clock-sec
Current instruction count. Appears when execution record/replay is enabled. Used for "time-traveling" to match the moment in the recorded execution with the snapshots. This counter may be obtained through query-replay command (since 5.2)

1.3

ImageInfoSpecificQCow2EncryptionBase (Object)

The encryption format

2.10

ImageInfoSpecificQCow2Encryption (Object)

2.10

ImageInfoSpecificQCow2 (Object)

compatibility level
the filename of the external data file that is stored in the image and used as a default for opening the image (since: 4.0)
True if the external data file must stay valid as a standalone (read-only) raw image without looking at qcow2 metadata (since: 4.0)
true if the image has extended L2 entries; only valid for compat >= 1.1 (since 5.2)
on or off; only valid for compat >= 1.1
true if the image has been marked corrupt; only valid for compat >= 1.1 (since 2.2)
width of a refcount entry in bits (since 2.3)
details about encryption parameters; only set if image is encrypted (since 2.10)
A list of qcow2 bitmap details (since 4.0)
the image cluster compression method (since 5.1)

1.7

ImageInfoSpecificVmdk (Object)

The create type of VMDK image
Content id of image
Parent VMDK image's cid
List of extent files

1.7

VmdkExtentInfo (Object)

Information about a VMDK extent file

Name of the extent file
Extent type (e.g. FLAT or SPARSE)
Number of bytes covered by this extent
Cluster size in bytes (for non-flat extents)
Whether this extent contains compressed data

8.0

ImageInfoSpecificRbd (Object)

Image encryption format

6.1

ImageInfoSpecificFile (Object)

Extent size hint (if available)

8.0

ImageInfoSpecificKind (Enum)

Since 2.7
Since 6.1
Since 8.0
Not documented
Not documented

1.7

ImageInfoSpecificQCow2Wrapper (Object)

Not documented

1.7

ImageInfoSpecificVmdkWrapper (Object)

Not documented

6.1

ImageInfoSpecificLUKSWrapper (Object)

Not documented

2.7

ImageInfoSpecificRbdWrapper (Object)

Not documented

6.1

ImageInfoSpecificFileWrapper (Object)

Not documented

8.0

ImageInfoSpecific (Object)

A discriminated record of image format specific information structures.

Not documented

1.7

BlockNodeInfo (Object)

Information about a QEMU image file

name of the image file
format of the image file
maximum capacity in bytes of the image
actual size on disk in bytes of the image
true if image is not cleanly closed
size of a cluster in bytes
true if the image is encrypted
true if the image is compressed (Since 1.7)
name of the backing file
full path of the backing file
the format of the backing file
list of VM snapshots
structure supplying additional format-specific information (since 1.7)

8.0

ImageInfo (Object)

Information about a QEMU image file, and potentially its backing image

info of the backing image

1.3

BlockChildInfo (Object)

Information about all nodes in the block graph starting at some node, annotated with information about that node in relation to its parent.

Child name of the root node in the BlockGraphInfo struct, in its role as the child of some undescribed parent node
Block graph information starting at this node

8.0

BlockGraphInfo (Object)

Information about all nodes in a block (sub)graph in the form of BlockNodeInfo data. The base BlockNodeInfo struct contains the information for the (sub)graph's root node.

Array of links to this node's child nodes' information

8.0

ImageCheck (Object)

Information about a QEMU image file check

name of the image file checked
format of the image file checked
number of unexpected errors occurred during check
offset (in bytes) where the image ends, this field is present if the driver for the image format supports it
number of corruptions found during the check if any
number of leaks found during the check if any
number of corruptions fixed during the check if any
number of leaks fixed during the check if any
total number of clusters, this field is present if the driver for the image format supports it
total number of allocated clusters, this field is present if the driver for the image format supports it
total number of fragmented clusters, this field is present if the driver for the image format supports it
total number of compressed clusters, this field is present if the driver for the image format supports it

1.4

MapEntry (Object)

Mapping information from a virtual block range to a host file range

virtual (guest) offset of the first byte described by this entry
the number of bytes of the mapped virtual range
reading the image will actually read data from a file (in particular, if offset is present this means that the sectors are not simply preallocated, but contain actual data in raw format)
whether the virtual blocks read as zeroes
true if the data is stored compressed (since 8.2)
number of layers (0 = top image, 1 = top image's backing file, ..., n - 1 = bottom image (where n is the number of images in the chain)) before reaching one for which the range is allocated
true if this layer provides the data, false if adding a backing layer could impact this region (since 6.1)
if present, the image file stores the data for this range in raw format at the given (host) offset
filename that is referred to by offset

2.6

BlockdevCacheInfo (Object)

Cache mode information for a block device

true if writeback mode is enabled
true if the host page cache is bypassed (O_DIRECT)
true if flush requests are ignored for the device

2.3

BlockDeviceInfo (Object)

Information about the backing device for a block device.

the filename of the backing device
the name of the block driver node (Since 2.0)
true if the backing device was open read-only
the name of the block format used to open the backing device. As of 0.14 this can be: 'blkdebug', 'bochs', 'cloop', 'cow', 'dmg', 'file', 'file', 'ftp', 'ftps', 'host_cdrom', 'host_device', 'http', 'https', 'luks', 'nbd', 'parallels', 'qcow', 'qcow2', 'raw', 'vdi', 'vmdk', 'vpc', 'vvfat' 2.2: 'archipelago' added, 'cow' dropped 2.3: 'host_floppy' deprecated 2.5: 'host_floppy' dropped 2.6: 'luks' added 2.8: 'replication' added, 'tftp' dropped 2.9: 'archipelago' dropped
the name of the backing file (for copy-on-write)
number of files in the backing file chain (since: 1.2)
true if the backing device is encrypted
detect and optimize zero writes (Since 2.1)
total throughput limit in bytes per second is specified
read throughput limit in bytes per second is specified
write throughput limit in bytes per second is specified
total I/O operations per second is specified
read I/O operations per second is specified
write I/O operations per second is specified
the info of image used (since: 1.6)
total throughput limit during bursts, in bytes (Since 1.7)
read throughput limit during bursts, in bytes (Since 1.7)
write throughput limit during bursts, in bytes (Since 1.7)
total I/O operations per second during bursts, in bytes (Since 1.7)
read I/O operations per second during bursts, in bytes (Since 1.7)
write I/O operations per second during bursts, in bytes (Since 1.7)
maximum length of the bps_max burst period, in seconds. (Since 2.6)
maximum length of the bps_rd_max burst period, in seconds. (Since 2.6)
maximum length of the bps_wr_max burst period, in seconds. (Since 2.6)
maximum length of the iops burst period, in seconds. (Since 2.6)
maximum length of the iops_rd_max burst period, in seconds. (Since 2.6)
maximum length of the iops_wr_max burst period, in seconds. (Since 2.6)
an I/O size in bytes (Since 1.7)
throttle group name (Since 2.4)
the cache mode used for the block device (since: 2.3)
configured write threshold for the device. 0 if disabled. (Since 2.3)
dirty bitmaps information (only present if node has one or more dirty bitmaps) (Since 4.2)

0.14

BlockDeviceIoStatus (Enum)

An enumeration of block device I/O status.

The last I/O operation has succeeded
The last I/O operation has failed
The last I/O operation has failed due to a no-space condition

1.0

BlockDirtyInfo (Object)

Block dirty bitmap information.

the name of the dirty bitmap (Since 2.4)
number of dirty bytes according to the dirty bitmap
granularity of the dirty bitmap in bytes (since 1.4)
true if the bitmap is recording new writes from the guest. (since 4.0)
true if the bitmap is in-use by some operation (NBD or jobs) and cannot be modified via QMP or used by another operation. (since 4.0)
true if the bitmap was stored on disk, is scheduled to be stored on disk, or both. (since 4.0)
true if this is a persistent bitmap that was improperly stored. Implies persistent to be true; recording and busy to be false. This bitmap cannot be used. To remove it, use block-dirty-bitmap-remove. (Since 4.0)

1.3

Qcow2BitmapInfoFlags (Enum)

An enumeration of flags that a bitmap can report to the user.

This flag is set by any process actively modifying the qcow2 file, and cleared when the updated bitmap is flushed to the qcow2 image. The presence of this flag in an offline image means that the bitmap was not saved correctly after its last usage, and may contain inconsistent data.
The bitmap must reflect all changes of the virtual disk by any application that would write to this qcow2 file.

4.0

Qcow2BitmapInfo (Object)

Qcow2 bitmap information.

the name of the bitmap
granularity of the bitmap in bytes
flags of the bitmap

4.0

BlockLatencyHistogramInfo (Object)

Block latency histogram.

list of interval boundary values in nanoseconds, all greater than zero and in ascending order. For example, the list [10, 50, 100] produces the following histogram intervals: [0, 10), [10, 50), [50, 100), [100, +inf).
list of io request counts corresponding to histogram intervals, one more element than boundaries has. For the example above, bins may be something like [3, 1, 5, 2], and corresponding histogram looks like:
5|           *
4|           *
3| *         *
2| *         *    *
1| *    *    *    *
 +------------------
     10   50   100

4.0

BlockInfo (Object)

Block device information. This structure describes a virtual device and the backing device associated with it.

The device name associated with the virtual device.
The qdev ID, or if no ID is assigned, the QOM path of the block device. (since 2.10)
This field is returned only for compatibility reasons, it should not be used (always returns 'unknown')
True if the device supports removable media.
True if the guest has locked this device from having its media removed
True if the device's tray is open (only present if it has a tray)
BlockDeviceIoStatus. Only present if the device supports it and the VM is configured to stop on errors (supported device models: virtio-blk, IDE, SCSI except scsi-generic)
BlockDeviceInfo describing the device if media is present

0.14

BlockMeasureInfo (Object)

Image file size calculation information. This structure describes the size requirements for creating a new image file.

The size requirements depend on the new image file format. File size always equals virtual disk size for the 'raw' format, even for sparse POSIX files. Compact formats such as 'qcow2' represent unallocated and zero regions efficiently so file size may be smaller than virtual disk size.

The values are upper bounds that are guaranteed to fit the new image file. Subsequent modification, such as internal snapshot or further bitmap creation, may require additional space and is not covered here.

Size required for a new image file, in bytes, when copying just allocated guest-visible contents.
Image file size, in bytes, once data has been written to all sectors, when copying just guest-visible contents.
Additional size required if all the top-level bitmap metadata in the source image were to be copied to the destination, present only when source and destination both support persistent bitmaps. (since 5.1)

2.10

query-block (Command)

Get a list of BlockInfo for all virtual block devices.

a list of BlockInfo describing each virtual block device. Filter nodes that were created implicitly are skipped over.

0.14

-> { "execute": "query-block" }
<- {
      "return":[
         {
            "io-status": "ok",
            "device":"ide0-hd0",
            "locked":false,
            "removable":false,
            "inserted":{
               "ro":false,
               "drv":"qcow2",
               "encrypted":false,
               "file":"disks/test.qcow2",
               "backing_file_depth":1,
               "bps":1000000,
               "bps_rd":0,
               "bps_wr":0,
               "iops":1000000,
               "iops_rd":0,
               "iops_wr":0,
               "bps_max": 8000000,
               "bps_rd_max": 0,
               "bps_wr_max": 0,
               "iops_max": 0,
               "iops_rd_max": 0,
               "iops_wr_max": 0,
               "iops_size": 0,
               "detect_zeroes": "on",
               "write_threshold": 0,
               "image":{
                  "filename":"disks/test.qcow2",
                  "format":"qcow2",
                  "virtual-size":2048000,
                  "backing_file":"base.qcow2",
                  "full-backing-filename":"disks/base.qcow2",
                  "backing-filename-format":"qcow2",
                  "snapshots":[
                     {
                        "id": "1",
                        "name": "snapshot1",
                        "vm-state-size": 0,
                        "date-sec": 10000200,
                        "date-nsec": 12,
                        "vm-clock-sec": 206,
                        "vm-clock-nsec": 30
                     }
                  ],
                  "backing-image":{
                      "filename":"disks/base.qcow2",
                      "format":"qcow2",
                      "virtual-size":2048000
                  }
               }
            },
            "qdev": "ide_disk",
            "type":"unknown"
         },
         {
            "io-status": "ok",
            "device":"ide1-cd0",
            "locked":false,
            "removable":true,
            "qdev": "/machine/unattached/device[23]",
            "tray_open": false,
            "type":"unknown"
         },
         {
            "device":"floppy0",
            "locked":false,
            "removable":true,
            "qdev": "/machine/unattached/device[20]",
            "type":"unknown"
         },
         {
            "device":"sd0",
            "locked":false,
            "removable":true,
            "type":"unknown"
         }
      ]
   }

BlockDeviceTimedStats (Object)

Statistics of a block device during a given interval of time.

Interval used for calculating the statistics, in seconds.
Minimum latency of read operations in the defined interval, in nanoseconds.
Minimum latency of write operations in the defined interval, in nanoseconds.
Minimum latency of zone append operations in the defined interval, in nanoseconds (since 8.1)
Minimum latency of flush operations in the defined interval, in nanoseconds.
Maximum latency of read operations in the defined interval, in nanoseconds.
Maximum latency of write operations in the defined interval, in nanoseconds.
Maximum latency of zone append operations in the defined interval, in nanoseconds (since 8.1)
Maximum latency of flush operations in the defined interval, in nanoseconds.
Average latency of read operations in the defined interval, in nanoseconds.
Average latency of write operations in the defined interval, in nanoseconds.
Average latency of zone append operations in the defined interval, in nanoseconds (since 8.1)
Average latency of flush operations in the defined interval, in nanoseconds.
Average number of pending read operations in the defined interval.
Average number of pending write operations in the defined interval.
Average number of pending zone append operations in the defined interval (since 8.1).

2.5

BlockDeviceStats (Object)

Statistics of a virtual block device or a block backing device.

The number of bytes read by the device.
The number of bytes written by the device.
The number of bytes appended by the zoned devices (since 8.1)
The number of bytes unmapped by the device (Since 4.2)
The number of read operations performed by the device.
The number of write operations performed by the device.
The number of zone append operations performed by the zoned devices (since 8.1)
The number of cache flush operations performed by the device (since 0.15)
The number of unmap operations performed by the device (Since 4.2)
Total time spent on reads in nanoseconds (since 0.15).
Total time spent on writes in nanoseconds (since 0.15).
Total time spent on zone append writes in nanoseconds (since 8.1)
Total time spent on cache flushes in nanoseconds (since 0.15).
Total time spent on unmap operations in nanoseconds (Since 4.2)
The offset after the greatest byte written to the device. The intended use of this information is for growable sparse files (like qcow2) that are used on top of a physical device.
Number of read requests that have been merged into another request (Since 2.3).
Number of write requests that have been merged into another request (Since 2.3).
Number of zone append requests that have been merged into another request (since 8.1)
Number of unmap requests that have been merged into another request (Since 4.2)
Time since the last I/O operation, in nanoseconds. If the field is absent it means that there haven't been any operations yet (Since 2.5).
The number of failed read operations performed by the device (Since 2.5)
The number of failed write operations performed by the device (Since 2.5)
The number of failed zone append write operations performed by the zoned devices (since 8.1)
The number of failed flush operations performed by the device (Since 2.5)
The number of failed unmap operations performed by the device (Since 4.2)
The number of invalid read operations performed by the device (Since 2.5)
The number of invalid write operations performed by the device (Since 2.5)
The number of invalid zone append operations performed by the zoned device (since 8.1)
The number of invalid flush operations performed by the device (Since 2.5)
The number of invalid unmap operations performed by the device (Since 4.2)
Whether invalid operations are included in the last access statistics (Since 2.5)
Whether failed operations are included in the latency and last access statistics (Since 2.5)
Statistics specific to the set of previously defined intervals of time (Since 2.5)
BlockLatencyHistogramInfo. (Since 4.0)
BlockLatencyHistogramInfo. (Since 4.0)
BlockLatencyHistogramInfo. (since 8.1)
BlockLatencyHistogramInfo. (Since 4.0)

0.14

BlockStatsSpecificFile (Object)

File driver statistics

The number of successful discard operations performed by the driver.
The number of failed discard operations performed by the driver.
The number of bytes discarded by the driver.

4.2

BlockStatsSpecificNvme (Object)

NVMe driver statistics

The number of completion errors.
The number of aligned accesses performed by the driver.
The number of unaligned accesses performed by the driver.

5.2

BlockStatsSpecific (Object)

Block driver specific statistics

Not documented

4.2

BlockStats (Object)

Statistics of a virtual block device or a block backing device.

If the stats are for a virtual block device, the name corresponding to the virtual block device.
The node name of the device. (Since 2.3)
The qdev ID, or if no ID is assigned, the QOM path of the block device. (since 3.0)
A BlockDeviceStats for the device.
Optional driver-specific stats. (Since 4.2)
This describes the file block device if it has one. Contains recursively the statistics of the underlying protocol (e.g. the host file for a qcow2 image). If there is no underlying protocol, this field is omitted
This describes the backing block device if it has one. (Since 2.0)

0.14

query-blockstats (Command)

Query the BlockStats for all virtual block devices.

If true, the command will query all the block nodes that have a node name, in a list which will include "parent" information, but not "backing". If false or omitted, the behavior is as before - query all the device backends, recursively including their "parent" and "backing". Filter nodes that were created implicitly are skipped over in this mode. (Since 2.3)

A list of BlockStats for each virtual block devices.

0.14

-> { "execute": "query-blockstats" }
<- {
      "return":[
         {
            "device":"ide0-hd0",
            "parent":{
               "stats":{
                  "wr_highest_offset":3686448128,
                  "wr_bytes":9786368,
                  "wr_operations":751,
                  "rd_bytes":122567168,
                  "rd_operations":36772
                  "wr_total_times_ns":313253456
                  "rd_total_times_ns":3465673657
                  "flush_total_times_ns":49653
                  "flush_operations":61,
                  "rd_merged":0,
                  "wr_merged":0,
                  "idle_time_ns":2953431879,
                  "account_invalid":true,
                  "account_failed":false
               }
            },
            "stats":{
               "wr_highest_offset":2821110784,
               "wr_bytes":9786368,
               "wr_operations":692,
               "rd_bytes":122739200,
               "rd_operations":36604
               "flush_operations":51,
               "wr_total_times_ns":313253456
               "rd_total_times_ns":3465673657
               "flush_total_times_ns":49653,
               "rd_merged":0,
               "wr_merged":0,
               "idle_time_ns":2953431879,
               "account_invalid":true,
               "account_failed":false
            },
            "qdev": "/machine/unattached/device[23]"
         },
         {
            "device":"ide1-cd0",
            "stats":{
               "wr_highest_offset":0,
               "wr_bytes":0,
               "wr_operations":0,
               "rd_bytes":0,
               "rd_operations":0
               "flush_operations":0,
               "wr_total_times_ns":0
               "rd_total_times_ns":0
               "flush_total_times_ns":0,
               "rd_merged":0,
               "wr_merged":0,
               "account_invalid":false,
               "account_failed":false
            },
            "qdev": "/machine/unattached/device[24]"
         },
         {
            "device":"floppy0",
            "stats":{
               "wr_highest_offset":0,
               "wr_bytes":0,
               "wr_operations":0,
               "rd_bytes":0,
               "rd_operations":0
               "flush_operations":0,
               "wr_total_times_ns":0
               "rd_total_times_ns":0
               "flush_total_times_ns":0,
               "rd_merged":0,
               "wr_merged":0,
               "account_invalid":false,
               "account_failed":false
            },
            "qdev": "/machine/unattached/device[16]"
         },
         {
            "device":"sd0",
            "stats":{
               "wr_highest_offset":0,
               "wr_bytes":0,
               "wr_operations":0,
               "rd_bytes":0,
               "rd_operations":0
               "flush_operations":0,
               "wr_total_times_ns":0
               "rd_total_times_ns":0
               "flush_total_times_ns":0,
               "rd_merged":0,
               "wr_merged":0,
               "account_invalid":false,
               "account_failed":false
            }
         }
      ]
   }

BlockdevOnError (Enum)

An enumeration of possible behaviors for errors on I/O operations. The exact meaning depends on whether the I/O was initiated by a guest or by a block job

for guest operations, report the error to the guest; for jobs, cancel the job
ignore the error, only report a QMP event (BLOCK_IO_ERROR or BLOCK_JOB_ERROR). The backup, mirror and commit block jobs retry the failing request later and may still complete successfully. The stream block job continues to stream and will complete with an error.
same as stop on ENOSPC, same as report otherwise.
for guest operations, stop the virtual machine; for jobs, pause the job
inherit the error handling policy of the backend (since: 2.7)

1.3

MirrorSyncMode (Enum)

An enumeration of possible behaviors for the initial synchronization phase of storage mirroring.

copies data in the topmost image to the destination
copies data from all images to the destination
only copy data written from now on
only copy data described by the dirty bitmap. (since: 2.4)
only copy data described by the dirty bitmap. (since: 4.2) Behavior on completion is determined by the BitmapSyncMode.

1.3

BitmapSyncMode (Enum)

An enumeration of possible behaviors for the synchronization of a bitmap when used for data copy operations.

The bitmap is only synced when the operation is successful. This is the behavior always used for 'INCREMENTAL' backups.
The bitmap is never synchronized with the operation, and is treated solely as a read-only manifest of blocks to copy.
The bitmap is always synchronized with the operation, regardless of whether or not the operation was successful.

4.2

MirrorCopyMode (Enum)

An enumeration whose values tell the mirror block job when to trigger writes to the target.

copy data in background only.
when data is written to the source, write it (synchronously) to the target as well. In addition, data is copied in background just like in background mode.

3.0

BlockJobInfoMirror (Object)

Information specific to mirror block jobs.

Whether the source is actively synced to the target, i.e. same data and new writes are done synchronously to both.

Since 8.2

BlockJobInfo (Object)

Information about a long-running block device operation.

the job type ('stream' for image streaming)
The job identifier. Originally the device name but other values are allowed since QEMU 2.7
Estimated offset value at the completion of the job. This value can arbitrarily change while the job is running, in both directions.
Progress made until now. The unit is arbitrary and the value can only meaningfully be used for the ratio of offset to len. The value is monotonically increasing.
false if the job is known to be in a quiescent state, with no pending I/O. (Since 1.3)
whether the job is paused or, if busy is true, will pause itself as soon as possible. (Since 1.3)
the rate limit, bytes per second
the status of the job (since 1.3)
true if the job may be completed (since 2.2)
Current job state/status (since 2.12)
Job will finalize itself when PENDING, moving to the CONCLUDED state. (since 2.12)
Job will dismiss itself when CONCLUDED, moving to the NULL state and disappearing from the query list. (since 2.12)
Error information if the job did not complete successfully. Not set if the job completed successfully. (since 2.12.1)

1.1

query-block-jobs (Command)

Return information about long-running block device operations.

a list of BlockJobInfo for each active block job

1.1

block_resize (Command)

Resize a block image while a guest is running.

Either device or node-name must be set but not both.

the name of the device to get the image resized
graph node name to get the image resized (Since 2.0)
new image size in bytes

  • nothing on success
  • If device is not a valid block device, DeviceNotFound

0.14

-> { "execute": "block_resize",
     "arguments": { "device": "scratch", "size": 1073741824 } }
<- { "return": {} }

NewImageMode (Enum)

An enumeration that tells QEMU how to set the backing file path in a new image file.

QEMU should look for an existing image file.
QEMU should create a new image with absolute paths for the backing file. If there is no backing file available, the new image will not be backed either.

1.1

BlockdevSnapshotSync (Object)

Either device or node-name must be set but not both.

the name of the device to take a snapshot of.
graph node name to generate the snapshot from (Since 2.0)
the target of the new overlay image. If the file exists, or if it is a device, the overlay will be created in the existing file/device. Otherwise, a new file will be created.
the graph node name of the new image (Since 2.0)
the format of the overlay image, default is 'qcow2'.
whether and how QEMU should create a new image, default is 'absolute-paths'.

BlockdevSnapshot (Object)

device or node name that will have a snapshot taken.
reference to the existing block device that will become the overlay of node, as part of taking the snapshot. It must not have a current backing file (this can be achieved by passing "backing": null to blockdev-add).

2.5

BackupPerf (Object)

Optional parameters for backup. These parameters don't affect functionality, but may significantly affect performance.

Use copy offloading. Default false.
Maximum number of parallel requests for the sustained background copying process. Doesn't influence copy-before-write operations. Default 64.
Maximum request length for the sustained background copying process. Doesn't influence copy-before-write operations. 0 means unlimited. If max-chunk is non-zero then it should not be less than job cluster size which is calculated as maximum of target image cluster size and 64k. Default 0.

6.0

BackupCommon (Object)

identifier for the newly-created block job. If omitted, the device name will be used. (Since 2.7)
the device name or node-name of a root node which should be copied.
what parts of the disk image should be copied to the destination (all the disk, only the sectors allocated in the topmost image, from a dirty bitmap, or only new I/O).
the maximum speed, in bytes per second. The default is 0, for unlimited.
The name of a dirty bitmap to use. Must be present if sync is "bitmap" or "incremental". Can be present if sync is "full" or "top". Must not be present otherwise. (Since 2.4 (drive-backup), 3.1 (blockdev-backup))
Specifies the type of data the bitmap should contain after the operation concludes. Must be present if a bitmap was provided, Must NOT be present otherwise. (Since 4.2)
true to compress data, if the target format supports it. (default: false) (since 2.8)
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 (see BlockInfo).
the action to take on an error on the target, default 'report' (no limitations, since this applies to a different block device than device).
When false, this job will wait in a PENDING state after it has finished its work, waiting for block-job-finalize before making any block graph changes. When true, this job will automatically perform its abort or commit actions. Defaults to true. (Since 2.12)
When false, this job will wait in a CONCLUDED state after it has completely ceased all work, and awaits block-job-dismiss. When true, this job will automatically disappear from the query list without user intervention. Defaults to true. (Since 2.12)
the node name that should be assigned to the filter driver that the backup job inserts into the graph above node specified by drive. If this option is not given, a node name is autogenerated. (Since: 4.2)
Performance options. (Since 6.0)

Member x-perf is experimental.

on-source-error and on-target-error only affect background I/O. If an error occurs during a guest write request, the device's rerror/werror actions will be used.

4.2

DriveBackup (Object)

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.
the format of the new destination, default is to probe if mode is 'existing', else the format of the source
whether and how QEMU should create a new image, default is 'absolute-paths'.

1.6

BlockdevBackup (Object)

the device name or node-name of the backup target node.

2.3

blockdev-snapshot-sync (Command)

Takes a synchronous snapshot of a block device.

For the arguments, see the documentation of BlockdevSnapshotSync.

  • nothing on success
  • If device is not a valid block device, DeviceNotFound

0.14

-> { "execute": "blockdev-snapshot-sync",
     "arguments": { "device": "ide-hd0",
                    "snapshot-file":
                    "/some/place/my-image",
                    "format": "qcow2" } }
<- { "return": {} }

blockdev-snapshot (Command)

Takes a snapshot of a block device.

Take a snapshot, by installing 'node' as the backing image of 'overlay'. Additionally, if 'node' is associated with a block device, the block device changes to using 'overlay' as its new active image.

For the arguments, see the documentation of BlockdevSnapshot.

If present, the check whether this operation is safe was relaxed so that it can be used to change backing file of a destination of a blockdev-mirror. (since 5.0)

2.5

-> { "execute": "blockdev-add",
     "arguments": { "driver": "qcow2",
                    "node-name": "node1534",
                    "file": { "driver": "file",
                              "filename": "hd1.qcow2" },
                    "backing": null } }
<- { "return": {} }
-> { "execute": "blockdev-snapshot",
     "arguments": { "node": "ide-hd0",
                    "overlay": "node1534" } }
<- { "return": {} }

change-backing-file (Command)

Change the backing file in the image file metadata. This does not cause QEMU to reopen the image file to reparse the backing filename (it may, however, perform a reopen to change permissions from r/o -> r/w -> r/o, if needed). The new backing file string is written into the image file metadata, and the QEMU internal strings are updated.

The name of the block driver state node of the image to modify. The "device" argument is used to verify "image-node-name" is in the chain described by "device".
The device name or node-name of the root node that owns image-node-name.
The string to write as the backing file. This string is not validated, so care should be taken when specifying the string or the image chain may not be able to be reopened again.

  • Nothing on success
  • If "device" does not exist or cannot be determined, DeviceNotFound

2.1

block-commit (Command)

Live commit of data from overlay image nodes into backing nodes - i.e., writes data between 'top' and 'base' into 'base'.

If top == base, that is an error. If top has no overlays on top of it, or if it is in use by a writer, the job will not be completed by itself. The 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.

identifier for the newly-created block job. If omitted, the device name will be used. (Since 2.7)
the device name or node-name of a root node
The node name of the backing image to write data into. If not specified, this is the deepest backing image. (since: 3.1)
Same as base-node, except that it is a file name rather than a node name. This must be the exact filename string that was used to open the node; other strings, even if addressing the same file, are not accepted
The node 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. (since: 3.1)
Same as top-node, except that it is a file name rather than a node name. This must be the exact filename string that was used to open the node; other strings, even if addressing the same file, are not accepted
The backing file string to write into the overlay image of 'top'. If 'top' does not have an overlay image, or if 'top' is in use by a writer, 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. (Since 2.1)

the maximum speed, in bytes per second
the action to take on an error. 'ignore' means that the request should be retried. (default: report; Since: 5.0)
the node name that should be assigned to the filter driver that the commit job inserts into the graph above top. If this option is not given, a node name is autogenerated. (Since: 2.9)
When false, this job will wait in a PENDING state after it has finished its work, waiting for block-job-finalize before making any block graph changes. When true, this job will automatically perform its abort or commit actions. Defaults to true. (Since 3.1)
When false, this job will wait in a CONCLUDED state after it has completely ceased all work, and awaits block-job-dismiss. When true, this job will automatically disappear from the query list without user intervention. Defaults to true. (Since 3.1)

Members base and top are deprecated. Use base-node and top-node instead.

  • Nothing on success
  • If device does not exist, DeviceNotFound
  • Any other error returns a GenericError.

1.3

-> { "execute": "block-commit",
     "arguments": { "device": "virtio0",
                    "top": "/tmp/snap1.qcow2" } }
<- { "return": {} }

drive-backup (Command)

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.

This command is deprecated. Use blockdev-backup instead.

  • nothing on success
  • If device is not a valid block device, GenericError

1.6

-> { "execute": "drive-backup",
     "arguments": { "device": "drive0",
                    "sync": "full",
                    "target": "backup.img" } }
<- { "return": {} }

blockdev-backup (Command)

Start a point-in-time copy of a block device to a new destination. The status of ongoing blockdev-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.

  • nothing on success
  • If device is not a valid block device, DeviceNotFound

2.3

-> { "execute": "blockdev-backup",
     "arguments": { "device": "src-id",
                    "sync": "full",
                    "target": "tgt-id" } }
<- { "return": {} }

query-named-block-nodes (Command)

Get the named block driver list

Omit the nested data about backing image ("backing-image" key) if true. Default is false (Since 5.0)

the list of BlockDeviceInfo

2.0

-> { "execute": "query-named-block-nodes" }
<- { "return": [ { "ro":false,
                   "drv":"qcow2",
                   "encrypted":false,
                   "file":"disks/test.qcow2",
                   "node-name": "my-node",
                   "backing_file_depth":1,
                   "detect_zeroes":"off",
                   "bps":1000000,
                   "bps_rd":0,
                   "bps_wr":0,
                   "iops":1000000,
                   "iops_rd":0,
                   "iops_wr":0,
                   "bps_max": 8000000,
                   "bps_rd_max": 0,
                   "bps_wr_max": 0,
                   "iops_max": 0,
                   "iops_rd_max": 0,
                   "iops_wr_max": 0,
                   "iops_size": 0,
                   "write_threshold": 0,
                   "image":{
                      "filename":"disks/test.qcow2",
                      "format":"qcow2",
                      "virtual-size":2048000,
                      "backing_file":"base.qcow2",
                      "full-backing-filename":"disks/base.qcow2",
                      "backing-filename-format":"qcow2",
                      "snapshots":[
                         {
                            "id": "1",
                            "name": "snapshot1",
                            "vm-state-size": 0,
                            "date-sec": 10000200,
                            "date-nsec": 12,
                            "vm-clock-sec": 206,
                            "vm-clock-nsec": 30
                         }
                      ],
                      "backing-image":{
                          "filename":"disks/base.qcow2",
                          "format":"qcow2",
                          "virtual-size":2048000
                      }
                   } } ] }

XDbgBlockGraphNodeType (Enum)

corresponds to BlockBackend
corresponds to BlockJob
corresponds to BlockDriverState

4.0

XDbgBlockGraphNode (Object)

Block graph node identifier. This id is generated only for x-debug-query-block-graph and does not relate to any other identifiers in Qemu.
Type of graph node. Can be one of block-backend, block-job or block-driver-state.
Human readable name of the node. Corresponds to node-name for block-driver-state nodes; is not guaranteed to be unique in the whole graph (with block-jobs and block-backends).

4.0

BlockPermission (Enum)

Enum of base block permissions.

A user that has the "permission" of consistent reads is guaranteed that their view of the contents of the block device is complete and self-consistent, representing the contents of a disk at a specific point. For most block devices (including their backing files) this is true, but the property cannot be maintained in a few situations like for intermediate nodes of a commit block job.
This permission is required to change the visible disk contents.
This permission (which is weaker than BLK_PERM_WRITE) is both enough and required for writes to the block node when the caller promises that the visible disk content doesn't change. As the BLK_PERM_WRITE permission is strictly stronger, either is sufficient to perform an unchanging write.
This permission is required to change the size of a block node.

4.0

XDbgBlockGraphEdge (Object)

Block Graph edge description for x-debug-query-block-graph.

parent id
child id
name of the relation (examples are 'file' and 'backing')
granted permissions for the parent operating on the child
permissions that can still be granted to other users of the child while it is still attached to this parent

4.0

XDbgBlockGraph (Object)

Block Graph - list of nodes and list of edges.

Not documented
Not documented

4.0

x-debug-query-block-graph (Command)

Get the block graph.

This command is meant for debugging.

4.0

drive-mirror (Command)

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.

  • nothing on success
  • If device is not a valid block device, GenericError

1.3

-> { "execute": "drive-mirror",
     "arguments": { "device": "ide-hd0",
                    "target": "/some/place/my-image",
                    "sync": "full",
                    "format": "qcow2" } }
<- { "return": {} }

DriveMirror (Object)

A set of parameters describing drive mirror setup.

identifier for the newly-created block job. If omitted, the device name will be used. (Since 2.7)
the device name or node-name of a root node whose writes should be mirrored.
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.
the format of the new destination, default is to probe if mode is 'existing', else the format of the source
the new block driver state node name in the graph (Since 2.1)
with sync=full graph node name to be replaced by the new image when a whole image copy is done. This can be used to repair broken Quorum files. By default, device is replaced, although implicitly created filters on it are kept. (Since 2.1)
whether and how QEMU should create a new image, default is 'absolute-paths'.
the maximum speed, in bytes per second
what parts of the disk image should be copied to the destination (all the disk, only the sectors allocated in the topmost image, or only new I/O).
granularity of the dirty bitmap, default is 64K if the image format doesn't have clusters, 4K if the clusters are smaller than that, else the cluster size. Must be a power of 2 between 512 and 64M (since 1.4).
maximum amount of data in flight from source to target (since 1.4).
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 (see BlockInfo).
the action to take on an error on the target, default 'report' (no limitations, since this applies to a different block device than device).
Whether to try to unmap target sectors where source has only zero. If true, and target unallocated sectors will read as zero, target image sectors will be unmapped; otherwise, zeroes will be written. Both will result in identical contents. Default is true. (Since 2.4)
when to copy data to the destination; defaults to 'background' (Since: 3.0)
When false, this job will wait in a PENDING state after it has finished its work, waiting for block-job-finalize before making any block graph changes. When true, this job will automatically perform its abort or commit actions. Defaults to true. (Since 3.1)
When false, this job will wait in a CONCLUDED state after it has completely ceased all work, and awaits block-job-dismiss. When true, this job will automatically disappear from the query list without user intervention. Defaults to true. (Since 3.1)

1.3

BlockDirtyBitmap (Object)

name of device/node which the bitmap is tracking
name of the dirty bitmap

2.4

BlockDirtyBitmapAdd (Object)

name of device/node which the bitmap is tracking
name of the dirty bitmap (must be less than 1024 bytes)
the bitmap granularity, default is 64k for block-dirty-bitmap-add
the bitmap is persistent, i.e. it will be saved to the corresponding block device image file on its close. For now only Qcow2 disks support persistent bitmaps. Default is false for block-dirty-bitmap-add. (Since: 2.10)
the bitmap is created in the disabled state, which means that it will not track drive changes. The bitmap may be enabled with block-dirty-bitmap-enable. Default is false. (Since: 4.0)

2.4

BlockDirtyBitmapOrStr (Alternate)

name of the bitmap, attached to the same node as target bitmap.
bitmap with specified node

4.1

BlockDirtyBitmapMerge (Object)

name of device/node which the target bitmap is tracking
name of the destination dirty bitmap
name(s) of the source dirty bitmap(s) at node and/or fully specified BlockDirtyBitmap elements. The latter are supported since 4.1.

4.0

block-dirty-bitmap-add (Command)

Create a dirty bitmap with a name on the node, and start tracking the writes.

  • nothing on success
  • If node is not a valid block device or node, DeviceNotFound
  • If name is already taken, GenericError with an explanation

2.4

-> { "execute": "block-dirty-bitmap-add",
     "arguments": { "node": "drive0", "name": "bitmap0" } }
<- { "return": {} }

block-dirty-bitmap-remove (Command)

Stop write tracking and remove the dirty bitmap that was created with block-dirty-bitmap-add. If the bitmap is persistent, remove it from its storage too.

  • nothing on success
  • If node is not a valid block device or node, DeviceNotFound
  • If name is not found, GenericError with an explanation
  • if name is frozen by an operation, GenericError

2.4

-> { "execute": "block-dirty-bitmap-remove",
     "arguments": { "node": "drive0", "name": "bitmap0" } }
<- { "return": {} }

block-dirty-bitmap-clear (Command)

Clear (reset) a dirty bitmap on the device, so that an incremental backup from this point in time forward will only backup clusters modified after this clear operation.

  • nothing on success
  • If node is not a valid block device, DeviceNotFound
  • If name is not found, GenericError with an explanation

2.4

-> { "execute": "block-dirty-bitmap-clear",
     "arguments": { "node": "drive0", "name": "bitmap0" } }
<- { "return": {} }

block-dirty-bitmap-enable (Command)

Enables a dirty bitmap so that it will begin tracking disk changes.

  • nothing on success
  • If node is not a valid block device, DeviceNotFound
  • If name is not found, GenericError with an explanation

4.0

-> { "execute": "block-dirty-bitmap-enable",
     "arguments": { "node": "drive0", "name": "bitmap0" } }
<- { "return": {} }

block-dirty-bitmap-disable (Command)

Disables a dirty bitmap so that it will stop tracking disk changes.

  • nothing on success
  • If node is not a valid block device, DeviceNotFound
  • If name is not found, GenericError with an explanation

4.0

-> { "execute": "block-dirty-bitmap-disable",
     "arguments": { "node": "drive0", "name": "bitmap0" } }
<- { "return": {} }

block-dirty-bitmap-merge (Command)

Merge dirty bitmaps listed in bitmaps to the target dirty bitmap. Dirty bitmaps in bitmaps will be unchanged, except if it also appears as the target bitmap. Any bits already set in target will still be set after the merge, i.e., this operation does not clear the target. On error, target is unchanged.

The resulting bitmap will count as dirty any clusters that were dirty in any of the source bitmaps. This can be used to achieve backup checkpoints, or in simpler usages, to copy bitmaps.

  • nothing on success
  • If node is not a valid block device, DeviceNotFound
  • If any bitmap in bitmaps or target is not found, GenericError
  • If any of the bitmaps have different sizes or granularities, GenericError

4.0

-> { "execute": "block-dirty-bitmap-merge",
     "arguments": { "node": "drive0", "target": "bitmap0",
                    "bitmaps": ["bitmap1"] } }
<- { "return": {} }

BlockDirtyBitmapSha256 (Object)

SHA256 hash of dirty bitmap data

ASCII representation of SHA256 bitmap hash

2.10

x-debug-block-dirty-bitmap-sha256 (Command)

Get bitmap SHA256.

This command is meant for debugging.

  • BlockDirtyBitmapSha256 on success
  • If node is not a valid block device, DeviceNotFound
  • If name is not found or if hashing has failed, GenericError with an explanation

2.10

blockdev-mirror (Command)

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

identifier for the newly-created block job. If omitted, the device name will be used. (Since 2.7)
The device name or node-name of a root node whose writes should be mirrored.
the id or node-name of the block device to mirror to. This mustn't be attached to guest.
with sync=full graph node name to be replaced by the new image when a whole image copy is done. This can be used to repair broken Quorum files. By default, device is replaced, although implicitly created filters on it are kept.
the maximum speed, in bytes per second
what parts of the disk image should be copied to the destination (all the disk, only the sectors allocated in the topmost image, or only new I/O).
granularity of the dirty bitmap, default is 64K if the image format doesn't have clusters, 4K if the clusters are smaller than that, else the cluster size. Must be a power of 2 between 512 and 64M
maximum amount of data in flight from source to target
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 (see BlockInfo).
the action to take on an error on the target, default 'report' (no limitations, since this applies to a different block device than device).
the node name that should be assigned to the filter driver that the mirror job inserts into the graph above device. If this option is not given, a node name is autogenerated. (Since: 2.9)
when to copy data to the destination; defaults to 'background' (Since: 3.0)
When false, this job will wait in a PENDING state after it has finished its work, waiting for block-job-finalize before making any block graph changes. When true, this job will automatically perform its abort or commit actions. Defaults to true. (Since 3.1)
When false, this job will wait in a CONCLUDED state after it has completely ceased all work, and awaits block-job-dismiss. When true, this job will automatically disappear from the query list without user intervention. Defaults to true. (Since 3.1)

nothing on success.

2.6

-> { "execute": "blockdev-mirror",
     "arguments": { "device": "ide-hd0",
                    "target": "target0",
                    "sync": "full" } }
<- { "return": {} }

BlockIOThrottle (Object)

A set of parameters describing block throttling.

Block device name
The name or QOM path of the guest device (since: 2.8)
total throughput limit in bytes per second
read throughput limit in bytes per second
write throughput limit in bytes per second
total I/O operations per second
read I/O operations per second
write I/O operations per second
total throughput limit during bursts, in bytes (Since 1.7)
read throughput limit during bursts, in bytes (Since 1.7)
write throughput limit during bursts, in bytes (Since 1.7)
total I/O operations per second during bursts, in bytes (Since 1.7)
read I/O operations per second during bursts, in bytes (Since 1.7)
write I/O operations per second during bursts, in bytes (Since 1.7)
maximum length of the bps_max burst period, in seconds. It must only be set if bps_max is set as well. Defaults to 1. (Since 2.6)
maximum length of the bps_rd_max burst period, in seconds. It must only be set if bps_rd_max is set as well. Defaults to 1. (Since 2.6)
maximum length of the bps_wr_max burst period, in seconds. It must only be set if bps_wr_max is set as well. Defaults to 1. (Since 2.6)
maximum length of the iops burst period, in seconds. It must only be set if iops_max is set as well. Defaults to 1. (Since 2.6)
maximum length of the iops_rd_max burst period, in seconds. It must only be set if iops_rd_max is set as well. Defaults to 1. (Since 2.6)
maximum length of the iops_wr_max burst period, in seconds. It must only be set if iops_wr_max is set as well. Defaults to 1. (Since 2.6)
an I/O size in bytes (Since 1.7)
throttle group name (Since 2.4)

Member device is deprecated. Use id instead.

1.1

ThrottleLimits (Object)

Limit parameters for throttling. Since some limit combinations are illegal, limits should always be set in one transaction. All fields are optional. When setting limits, if a field is missing the current value is not changed.

limit total I/O operations per second
I/O operations burst
length of the iops-total-max burst period, in seconds It must only be set if iops-total-max is set as well.
limit read operations per second
I/O operations read burst
length of the iops-read-max burst period, in seconds It must only be set if iops-read-max is set as well.
limit write operations per second
I/O operations write burst
length of the iops-write-max burst period, in seconds It must only be set if iops-write-max is set as well.
limit total bytes per second
total bytes burst
length of the bps-total-max burst period, in seconds. It must only be set if bps-total-max is set as well.
limit read bytes per second
total bytes read burst
length of the bps-read-max burst period, in seconds It must only be set if bps-read-max is set as well.
limit write bytes per second
total bytes write burst
length of the bps-write-max burst period, in seconds It must only be set if bps-write-max is set as well.
when limiting by iops max size of an I/O in bytes

2.11

ThrottleGroupProperties (Object)

Properties for throttle-group objects.

limits to apply for this throttle group
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented

All members starting with x- are aliases for the same key without x- in the limits object. This is not a stable interface and may be removed or changed incompatibly in the future. Use limits for a supported stable interface.

2.11

block-stream (Command)

Copy data from a backing file into a block device.

The block streaming operation is performed in the background until the entire backing file has been copied. This command returns immediately once streaming has started. The status of ongoing block streaming operations can be checked with query-block-jobs. The operation can be stopped before it has completed using the block-job-cancel command.

The node that receives the data is called the top image, can be located in any part of the chain (but always above the base image; see below) and can be specified using its device or node name. Earlier qemu versions only allowed 'device' to name the top level node; presence of the 'base-node' parameter during introspection can be used as a witness of the enhanced semantics of 'device'.

If a base file is specified then sectors are not copied from that base file and its backing chain. This can be used to stream a subset of the backing file chain instead of flattening the entire image. When streaming completes the image file will have the base file as its backing file, unless that node was changed while the job was running. In that case, base's parent's backing (or filtered, whichever exists) child (i.e., base at the beginning of the job) will be the new backing file.

On successful completion the image file is updated to drop the backing file and the BLOCK_JOB_COMPLETED event is emitted.

In case device is a filter node, block-stream modifies the first non-filter overlay node below it to point to the new backing node instead of modifying device itself.

identifier for the newly-created block job. If omitted, the device name will be used. (Since 2.7)
the device or node name of the top image
the common backing file name. It cannot be set if base-node or bottom is also set.
the node name of the backing file. It cannot be set if base or bottom is also set. (Since 2.8)
the last node in the chain that should be streamed into top. It cannot be set if base or base-node is also set. It cannot be filter node. (Since 6.0)
The backing file string to write into the top image. 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. (Since 2.1)

the maximum speed, in bytes per second
the action to take on an error (default report). 'stop' and 'enospc' can only be used if the block device supports io-status (see BlockInfo). (Since 1.3)
the node name that should be assigned to the filter driver that the stream job inserts into the graph above device. If this option is not given, a node name is autogenerated. (Since: 6.0)
When false, this job will wait in a PENDING state after it has finished its work, waiting for block-job-finalize before making any block graph changes. When true, this job will automatically perform its abort or commit actions. Defaults to true. (Since 3.1)
When false, this job will wait in a CONCLUDED state after it has completely ceased all work, and awaits block-job-dismiss. When true, this job will automatically disappear from the query list without user intervention. Defaults to true. (Since 3.1)

  • Nothing on success.
  • If device does not exist, DeviceNotFound.

1.1

-> { "execute": "block-stream",
     "arguments": { "device": "virtio0",
                    "base": "/tmp/master.qcow2" } }
<- { "return": {} }

block-job-set-speed (Command)

Set maximum speed for a background block operation.

This command can only be issued when there is an active block job.

Throttling can be disabled by setting the speed to 0.

The job identifier. This used to be a device name (hence the name of the parameter), but since QEMU 2.7 it can have other values.
the maximum speed, in bytes per second, or 0 for unlimited. Defaults to 0.

  • Nothing on success
  • If no background operation is active on this device, DeviceNotActive

1.1

block-job-cancel (Command)

Stop an active background block operation.

This command returns immediately after marking the active background block operation for cancellation. It is an error to call this command if no operation is in progress.

The operation will cancel as soon as possible and then emit the BLOCK_JOB_CANCELLED event. Before that happens the job is still visible when enumerated using query-block-jobs.

Note that if you issue 'block-job-cancel' after 'drive-mirror' has indicated (via the event BLOCK_JOB_READY) that the source and destination are synchronized, then the event triggered by this command changes to BLOCK_JOB_COMPLETED, to indicate that the mirroring has ended and the destination now has a point-in-time copy tied to the time of the cancellation.

For streaming, the image file retains its backing file unless the streaming operation happens to complete just as it is being cancelled. A new streaming operation can be started at a later time to finish copying all data from the backing file.

The job identifier. This used to be a device name (hence the name of the parameter), but since QEMU 2.7 it can have other values.
If true, and the job has already emitted the event BLOCK_JOB_READY, abandon the job immediately (even if it is paused) instead of waiting for the destination to complete its final synchronization (since 1.3)

  • Nothing on success
  • If no background operation is active on this device, DeviceNotActive

1.1

block-job-pause (Command)

Pause an active background block operation.

This command returns immediately after marking the active background block operation for pausing. It is an error to call this command if no operation is in progress or if the job is already paused.

The operation will pause as soon as possible. No event is emitted when the operation is actually paused. Cancelling a paused job automatically resumes it.

The job identifier. This used to be a device name (hence the name of the parameter), but since QEMU 2.7 it can have other values.

  • Nothing on success
  • If no background operation is active on this device, DeviceNotActive

1.3

block-job-resume (Command)

Resume an active background block operation.

This command returns immediately after resuming a paused background block operation. It is an error to call this command if no operation is in progress or if the job is not paused.

This command also clears the error status of the job.

The job identifier. This used to be a device name (hence the name of the parameter), but since QEMU 2.7 it can have other values.

  • Nothing on success
  • If no background operation is active on this device, DeviceNotActive

1.3

block-job-complete (Command)

Manually trigger completion of an active background block operation. This is supported for drive mirroring, where it also switches the device to write to the target path only. The ability to complete is signaled with a BLOCK_JOB_READY event.

This command completes an active background block operation synchronously. The ordering of this command's return with the BLOCK_JOB_COMPLETED event is not defined. Note that if an I/O error occurs during the processing of this command: 1) the command itself will fail; 2) the error will be processed according to the rerror/werror arguments that were specified when starting the operation.

A cancelled or paused job cannot be completed.

The job identifier. This used to be a device name (hence the name of the parameter), but since QEMU 2.7 it can have other values.

  • Nothing on success
  • If no background operation is active on this device, DeviceNotActive

1.3

block-job-dismiss (Command)

For jobs that have already concluded, remove them from the block-job-query list. This command only needs to be run for jobs which were started with QEMU 2.12+ job lifetime management semantics.

This command will refuse to operate on any job that has not yet reached its terminal state, JOB_STATUS_CONCLUDED. For jobs that make use of the BLOCK_JOB_READY event, block-job-cancel or block-job-complete will still need to be used as appropriate.

The job identifier.

Nothing on success

2.12

block-job-finalize (Command)

Once a job that has manual=true reaches the pending state, it can be instructed to finalize any graph changes and do any necessary cleanup via this command. For jobs in a transaction, instructing one job to finalize will force ALL jobs in the transaction to finalize, so it is only necessary to instruct a single member job to finalize.

The job identifier.

Nothing on success

2.12

BlockJobChangeOptionsMirror (Object)

Switch to this copy mode. Currently, only the switch from 'background' to 'write-blocking' is implemented.

8.2

BlockJobChangeOptions (Object)

Block job options that can be changed after job creation.

The job identifier
The job type

Since 8.2

block-job-change (Command)

Change the block job's options.

8.2

BlockdevDiscardOptions (Enum)

Determines how to handle discard requests.

Ignore the request
Forward as an unmap request

2.9

BlockdevDetectZeroesOptions (Enum)

Describes the operation mode for the automatic conversion of plain zero writes by the OS to driver specific optimized zero write commands.

Disabled (default)
Enabled
Enabled and even try to unmap blocks if possible. This requires also that BlockdevDiscardOptions is set to unmap for this device.

2.1

BlockdevAioOptions (Enum)

Selects the AIO backend to handle I/O requests

Use qemu's thread pool
Use native AIO backend (only Linux and Windows)
Use linux io_uring (since 5.0)

2.9

BlockdevCacheOptions (Object)

Includes cache-related options for block devices

enables use of O_DIRECT (bypass the host page cache; default: false)
ignore any flush requests for the device (default: false)

2.9

BlockdevDriver (Enum)

Drivers that are supported in block device operations.

Since 2.11
Since 2.12
Since 3.0
Since 3.0
Since 4.2
Since 5.0
Since 6.2
Since 7.0
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2.9

BlockdevOptionsFile (Object)

Driver specific block device options for the file backend.

path to the image file
the id for the object that will handle persistent reservations for this device (default: none, forward the commands via SG_IO; since 2.11)
AIO backend (default: threads) (since: 2.8)
maximum number of requests to batch together into a single submission in the AIO backend. The smallest value between this and the aio-max-batch value of the IOThread object is chosen. 0 means that the AIO backend will handle it automatically. (default: 0, since 6.2)
whether to enable file locking. If set to 'auto', only enable when Open File Descriptor (OFD) locking API is available (default: auto, since 2.10)
invalidate page cache during live migration. This prevents stale data on the migration destination with cache.direct=off. Currently only supported on Linux hosts. (default: on, since: 4.0)
whether to check that page cache was dropped on live migration. May cause noticeable delays if the image file is large, do not use in production. (default: off) (since: 3.0)

If present, enabled auto-read-only means that the driver will open the image read-only at first, dynamically reopen the image file read-write when the first writer is attached to the node and reopen read-only when the last writer is detached. This allows giving QEMU write permissions only on demand when an operation actually needs write access.
Member x-check-cache-dropped is meant for debugging.

2.9

BlockdevOptionsNull (Object)

Driver specific block device options for the null backend.

size of the device in bytes.
emulated latency (in nanoseconds) in processing requests. Default to zero which completes requests immediately. (Since 2.4)
if true, reads from the device produce zeroes; if false, the buffer is left unchanged. (default: false; since: 4.1)

2.9

BlockdevOptionsNVMe (Object)

Driver specific block device options for the NVMe backend.

PCI controller address of the NVMe device in format hhhh:bb:ss.f (host:bus:slot.function)
namespace number of the device, starting from 1.

Note that the PCI device must have been unbound from any host kernel driver before instructing QEMU to add the blockdev.

2.12

BlockdevOptionsVVFAT (Object)

Driver specific block device options for the vvfat protocol.

directory to be exported as FAT image
FAT type: 12, 16 or 32
whether to export a floppy image (true) or partitioned hard disk (false; default)
set the volume label, limited to 11 bytes. FAT16 and FAT32 traditionally have some restrictions on labels, which are ignored by most operating systems. Defaults to "QEMU VVFAT". (since 2.4)
whether to allow write operations (default: false)

2.9

BlockdevOptionsGenericFormat (Object)

Driver specific block device options for image format that have no option besides their data source.

reference to or definition of the data source block device

2.9

BlockdevOptionsLUKS (Object)

Driver specific block device options for LUKS.

the ID of a QCryptoSecret object providing the decryption key (since 2.6). Mandatory except when doing a metadata-only probe of the image.

2.9

BlockdevOptionsGenericCOWFormat (Object)

Driver specific block device options for image format that have no option besides their data source and an optional backing file.

reference to or definition of the backing file block device, null disables the backing file entirely. Defaults to the backing file stored the image file.

2.9

Qcow2OverlapCheckMode (Enum)

General overlap check modes.

Do not perform any checks
Perform only checks which can be done in constant time and without reading anything from disk
Perform only checks which can be done without reading anything from disk
Perform all available overlap checks

2.9

Qcow2OverlapCheckFlags (Object)

Structure of flags for each metadata structure. Setting a field to 'true' makes qemu guard that structure against unintended overwriting. The default value is chosen according to the template given.

Specifies a template mode which can be adjusted using the other flags, defaults to 'cached'
since 3.0
Not documented
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2.9

Qcow2OverlapChecks (Alternate)

Specifies which metadata structures should be guarded against unintended overwriting.

set of flags for separate specification of each metadata structure type
named mode which chooses a specific set of flags

2.9

BlockdevQcowEncryptionFormat (Enum)

AES-CBC with plain64 initialization vectors

2.10

BlockdevQcowEncryption (Object)

Not documented

2.10

BlockdevOptionsQcow (Object)

Driver specific block device options for qcow.

Image decryption options. Mandatory for encrypted images, except when doing a metadata-only probe of the image.

2.10

BlockdevQcow2EncryptionFormat (Enum)

AES-CBC with plain64 initialization vectors
Not documented

2.10

BlockdevQcow2Encryption (Object)

Not documented

2.10

BlockdevOptionsPreallocate (Object)

Filter driver intended to be inserted between format and protocol node and do preallocation in protocol node on write.

on preallocation, align file length to this number, default 1048576 (1M)
how much to preallocate, default 134217728 (128M)

6.0

BlockdevOptionsQcow2 (Object)

Driver specific block device options for qcow2.

whether to enable the lazy refcounts feature (default is taken from the image file)
whether discard requests to the qcow2 device should be forwarded to the data source
whether discard requests for the data source should be issued when a snapshot operation (e.g. deleting a snapshot) frees clusters in the qcow2 file
whether discard requests for the data source should be issued on other occasions where a cluster gets freed
when enabled, data clusters will remain preallocated when they are no longer used, e.g. because they are discarded or converted to zero clusters. As usual, whether the old data is discarded or kept on the protocol level (i.e. in the image file) depends on the setting of the pass-discard-request option. Keeping the clusters preallocated prevents qcow2 fragmentation that would otherwise be caused by freeing and re-allocating them later. Besides potential performance degradation, such fragmentation can lead to increased allocation of clusters past the end of the image file, resulting in image files whose file length can grow much larger than their guest disk size would suggest. If image file length is of concern (e.g. when storing qcow2 images directly on block devices), you should consider enabling this option. (since 8.1)
which overlap checks to perform for writes to the image, defaults to 'cached' (since 2.2)
the maximum total size of the L2 table and refcount block caches in bytes (since 2.2)
the maximum size of the L2 table cache in bytes (since 2.2)
the size of each entry in the L2 cache in bytes. It must be a power of two between 512 and the cluster size. The default value is the cluster size (since 2.12)
the maximum size of the refcount block cache in bytes (since 2.2)
clean unused entries in the L2 and refcount caches. The interval is in seconds. The default value is 600 on supporting platforms, and 0 on other platforms. 0 disables this feature. (since 2.5)
Image decryption options. Mandatory for encrypted images, except when doing a metadata-only probe of the image. (since 2.10)
reference to or definition of the external data file. This may only be specified for images that require an external data file. If it is not specified for such an image, the data file name is loaded from the image file. (since 4.0)

2.9

SshHostKeyCheckMode (Enum)

Don't check the host key at all
Compare the host key with a given hash
Check the host key against the known_hosts file

2.12

SshHostKeyCheckHashType (Enum)

The given hash is an md5 hash
The given hash is an sha1 hash
The given hash is an sha256 hash

2.12

SshHostKeyHash (Object)

The hash algorithm used for the hash
The expected hash value

2.12

SshHostKeyCheck (Object)

Not documented

2.12

BlockdevOptionsSsh (Object)

host address
path to the image on the host
user as which to connect, defaults to current local user name
Defines how and what to check the host key against (default: known_hosts)

2.9

BlkdebugEvent (Enum)

Trigger events supported by blkdebug.

write zeros to the l1 table to shrink image. (since 2.11)
discard the l2 tables. (since 2.11)
a write due to copy-on-read (since 2.11)
an allocation of file space for a cluster (since 4.1)
triggers once at creation of the blkdebug node (since 4.1)
Not documented
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2.9

BlkdebugIOType (Enum)

Kinds of I/O that blkdebug can inject errors in.

.bdrv_co_preadv()
.bdrv_co_pwritev()
.bdrv_co_pwrite_zeroes()
.bdrv_co_pdiscard()
.bdrv_co_flush_to_disk()
.bdrv_co_block_status()

4.1

BlkdebugInjectErrorOptions (Object)

Describes a single error injection for blkdebug.

trigger event
the state identifier blkdebug needs to be in to actually trigger the event; defaults to "any"
the type of I/O operations on which this error should be injected; defaults to "all read, write, write-zeroes, discard, and flush operations" (since: 4.1)
error identifier (errno) to be returned; defaults to EIO
specifies the sector index which has to be affected in order to actually trigger the event; defaults to "any sector"
disables further events after this one has been triggered; defaults to false
fail immediately; defaults to false

2.9

BlkdebugSetStateOptions (Object)

Describes a single state-change event for blkdebug.

trigger event
the current state identifier blkdebug needs to be in; defaults to "any"
the state identifier blkdebug is supposed to assume if this event is triggered

2.9

BlockdevOptionsBlkdebug (Object)

Driver specific block device options for blkdebug.

underlying raw block device (or image file)
filename of the configuration file
required alignment for requests in bytes, must be positive power of 2, or 0 for default
maximum size for I/O transfers in bytes, must be positive multiple of align and of the underlying file's request alignment (but need not be a power of 2), or 0 for default (since 2.10)
preferred alignment for write zero requests in bytes, must be positive multiple of align and of the underlying file's request alignment (but need not be a power of 2), or 0 for default (since 2.10)
maximum size for write zero requests in bytes, must be positive multiple of align, of opt-write-zero, and of the underlying file's request alignment (but need not be a power of 2), or 0 for default (since 2.10)
preferred alignment for discard requests in bytes, must be positive multiple of align and of the underlying file's request alignment (but need not be a power of 2), or 0 for default (since 2.10)
maximum size for discard requests in bytes, must be positive multiple of align, of opt-discard, and of the underlying file's request alignment (but need not be a power of 2), or 0 for default (since 2.10)
array of error injection descriptions
array of state-change descriptions
Permissions to take on image in addition to what is necessary anyway (which depends on how the blkdebug node is used). Defaults to none. (since 5.0)
Permissions not to share on image in addition to what cannot be shared anyway (which depends on how the blkdebug node is used). Defaults to none. (since 5.0)

2.9

BlockdevOptionsBlklogwrites (Object)

Driver specific block device options for blklogwrites.

block device
block device used to log writes to file
sector size used in logging writes to file, determines granularity of offsets and sizes of writes (default: 512)
append to an existing log (default: false)
interval of write requests after which the log super block is updated to disk (default: 4096)

3.0

BlockdevOptionsBlkverify (Object)

Driver specific block device options for blkverify.

block device to be tested
raw image used for verification

2.9

BlockdevOptionsBlkreplay (Object)

Driver specific block device options for blkreplay.

disk image which should be controlled with blkreplay

4.2

QuorumReadPattern (Enum)

An enumeration of quorum read patterns.

read all the children and do a quorum vote on reads
read only from the first child that has not failed

2.9

BlockdevOptionsQuorum (Object)

Driver specific block device options for Quorum

true if the driver must print content mismatch set to false by default
the children block devices to use
the vote limit under which a read will fail
rewrite corrupted data when quorum is reached (Since 2.1)
choose read pattern and set to quorum by default (Since 2.2)

2.9

BlockdevOptionsGluster (Object)

Driver specific block device options for Gluster

name of gluster volume where VM image resides
absolute path to image file in gluster volume
gluster servers description
libgfapi log level (default '4' which is Error) (Since 2.8)
libgfapi log file (default /dev/stderr) (Since 2.8)

2.9

BlockdevOptionsIoUring (Object)

Driver specific block device options for the io_uring backend.

path to the image file

7.2

CONFIG_BLKIO

BlockdevOptionsNvmeIoUring (Object)

Driver specific block device options for the nvme-io_uring backend.

path to the NVMe namespace's character device (e.g. /dev/ng0n1).

7.2

CONFIG_BLKIO

BlockdevOptionsVirtioBlkVfioPci (Object)

Driver specific block device options for the virtio-blk-vfio-pci backend.

path to the PCI device's sysfs directory (e.g. /sys/bus/pci/devices/0000:00:01.0).

7.2

CONFIG_BLKIO

BlockdevOptionsVirtioBlkVhostUser (Object)

Driver specific block device options for the virtio-blk-vhost-user backend.

path to the vhost-user UNIX domain socket.

7.2

CONFIG_BLKIO

BlockdevOptionsVirtioBlkVhostVdpa (Object)

Driver specific block device options for the virtio-blk-vhost-vdpa backend.

path to the vhost-vdpa character device.

Member path supports the special "/dev/fdset/N" path (since 8.1)

7.2

CONFIG_BLKIO

IscsiTransport (Enum)

An enumeration of libiscsi transport types

Not documented
Not documented

2.9

IscsiHeaderDigest (Enum)

An enumeration of header digests supported by libiscsi

Not documented
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2.9

BlockdevOptionsIscsi (Object)

The iscsi transport type
The address of the iscsi portal
The target iqn name
LUN to connect to. Defaults to 0.
User name to log in with. If omitted, no CHAP authentication is performed.
The ID of a QCryptoSecret object providing the password for the login. This option is required if user is specified.
The iqn name we want to identify to the target as. If this option is not specified, an initiator name is generated automatically.
The desired header digest. Defaults to none-crc32c.
Timeout in seconds after which a request will timeout. 0 means no timeout and is the default.

Driver specific block device options for iscsi

2.9

RbdAuthMode (Enum)

Not documented
Not documented

3.0

RbdImageEncryptionFormat (Enum)

Used for opening either luks or luks2 (Since 8.0)
Not documented
Not documented

6.1

RbdEncryptionOptionsLUKSBase (Object)

ID of a QCryptoSecret object providing a passphrase for unlocking the encryption

6.1

RbdEncryptionCreateOptionsLUKSBase (Object)

The encryption algorithm

6.1

RbdEncryptionOptionsLUKS (Object)

6.1

RbdEncryptionOptionsLUKS2 (Object)

6.1

RbdEncryptionOptionsLUKSAny (Object)

8.0

RbdEncryptionCreateOptionsLUKS (Object)

6.1

RbdEncryptionCreateOptionsLUKS2 (Object)

6.1

RbdEncryptionOptions (Object)

Encryption format.
Parent image encryption options (for cloned images). Can be left unspecified if this cloned image is encrypted using the same format and secret as its parent image (i.e. not explicitly formatted) or if its parent image is not encrypted. (Since 8.0)

6.1

RbdEncryptionCreateOptions (Object)

Not documented

6.1

BlockdevOptionsRbd (Object)

Ceph pool name.
Rados namespace name in the Ceph pool. (Since 5.0)
Image name in the Ceph pool.
path to Ceph configuration file. Values in the configuration file will be overridden by options specified via QAPI.
Ceph snapshot name.
Image encryption options. (Since 6.1)
Ceph id name.
Acceptable authentication modes. This maps to Ceph configuration option "auth_client_required". (Since 3.0)
ID of a QCryptoSecret object providing a key for cephx authentication. This maps to Ceph configuration option "key". (Since 3.0)
Monitor host address and port. This maps to the "mon_host" Ceph option.

2.9

ReplicationMode (Enum)

An enumeration of replication modes.

Primary mode, the vm's state will be sent to secondary QEMU.
Secondary mode, receive the vm's state from primary QEMU.

2.9

CONFIG_REPLICATION

BlockdevOptionsReplication (Object)

Driver specific block device options for replication

the replication mode
In secondary mode, node name or device ID of the root node who owns the replication node chain. Must not be given in primary mode.

2.9

CONFIG_REPLICATION

NFSTransport (Enum)

An enumeration of NFS transport types

TCP transport

2.9

NFSServer (Object)

Captures the address of the socket

transport type used for NFS (only TCP supported)
host address for NFS server

2.9

BlockdevOptionsNfs (Object)

Driver specific block device option for NFS

host address
path of the image on the host
UID value to use when talking to the server (defaults to 65534 on Windows and getuid() on unix)
GID value to use when talking to the server (defaults to 65534 on Windows and getgid() in unix)
number of SYNs during the session establishment (defaults to libnfs default)
set the readahead size in bytes (defaults to libnfs default)
set the pagecache size in bytes (defaults to libnfs default)
set the NFS debug level (max 2) (defaults to libnfs default)

2.9

BlockdevOptionsCurlBase (Object)

Driver specific block device options shared by all protocols supported by the curl backend.

URL of the image file
Size of the read-ahead cache; must be a multiple of 512 (defaults to 256 kB)
Timeout for connections, in seconds (defaults to 5)
Username for authentication (defaults to none)
ID of a QCryptoSecret object providing a password for authentication (defaults to no password)
Username for proxy authentication (defaults to none)
ID of a QCryptoSecret object providing a password for proxy authentication (defaults to no password)

2.9

BlockdevOptionsCurlHttp (Object)

Driver specific block device options for HTTP connections over the curl backend. URLs must start with "http://".

List of cookies to set; format is "name1=content1; name2=content2;" as explained by CURLOPT_COOKIE(3). Defaults to no cookies.
ID of a QCryptoSecret object providing the cookie data in a secure way. See cookie for the format. (since 2.10)

2.9

BlockdevOptionsCurlHttps (Object)

Driver specific block device options for HTTPS connections over the curl backend. URLs must start with "https://".

List of cookies to set; format is "name1=content1; name2=content2;" as explained by CURLOPT_COOKIE(3). Defaults to no cookies.
Whether to verify the SSL certificate's validity (defaults to true)
ID of a QCryptoSecret object providing the cookie data in a secure way. See cookie for the format. (since 2.10)

2.9

BlockdevOptionsCurlFtp (Object)

Driver specific block device options for FTP connections over the curl backend. URLs must start with "ftp://".

2.9

BlockdevOptionsCurlFtps (Object)

Driver specific block device options for FTPS connections over the curl backend. URLs must start with "ftps://".

Whether to verify the SSL certificate's validity (defaults to true)

2.9

BlockdevOptionsNbd (Object)

Driver specific block device options for NBD.

NBD server address
export name
TLS credentials ID
TLS hostname override for certificate validation (Since 7.0)
A metadata context name such as "qemu:dirty-bitmap:NAME" or "qemu:allocation-depth" to query in place of the traditional "base:allocation" block status (see NBD_OPT_LIST_META_CONTEXT in the NBD protocol; and yes, naming this option x-context would have made more sense) (since 3.0)
On an unexpected disconnect, the nbd client tries to connect again until succeeding or encountering a serious error. During the first reconnect-delay seconds, all requests are paused and will be rerun on a successful reconnect. After that time, any delayed requests and all future requests before a successful reconnect will immediately fail. Default 0 (Since 4.2)
In seconds. If zero, the nbd driver tries the connection only once, and fails to open if the connection fails. If non-zero, the nbd driver will repeat connection attempts until successful or until open-timeout seconds have elapsed. Default 0 (Since 7.0)

Member x-dirty-bitmap is experimental.

2.9

BlockdevOptionsRaw (Object)

Driver specific block device options for the raw driver.

position where the block device starts
the assumed size of the device

2.9

BlockdevOptionsThrottle (Object)

Driver specific block device options for the throttle driver

the name of the throttle-group object to use. It must already exist.
reference to or definition of the data source block device

2.11

BlockdevOptionsCor (Object)

Driver specific block device options for the copy-on-read driver.

The name of a non-filter node (allocation-bearing layer) that limits the COR operations in the backing chain (inclusive), so that no data below this node will be copied by this filter. If option is absent, the limit is not applied, so that data from all backing layers may be copied.

6.0

OnCbwError (Enum)

An enumeration of possible behaviors for copy-before-write operation failures.

report the error to the guest. This way, the guest will not be able to overwrite areas that cannot be backed up, so the backup process remains valid.
continue guest write. Doing so will make the provided snapshot state invalid and any backup or export process based on it will finally fail.

7.1

BlockdevOptionsCbw (Object)

Driver specific block device options for the copy-before-write driver, which does so called copy-before-write operations: when data is written to the filter, the filter first reads corresponding blocks from its file child and copies them to target child. After successfully copying, the write request is propagated to file child. If copying fails, the original write request is failed too and no data is written to file child.

The target for copy-before-write operations.
If specified, copy-before-write filter will do copy-before-write operations only for dirty regions of the bitmap. Bitmap size must be equal to length of file and target child of the filter. Note also, that bitmap is used only to initialize internal bitmap of the process, so further modifications (or removing) of specified bitmap doesn't influence the filter. (Since 7.0)
Behavior on failure of copy-before-write operation. Default is break-guest-write. (Since 7.1)
Zero means no limit. Non-zero sets the timeout in seconds for copy-before-write operation. When a timeout occurs, the respective copy-before-write operation will fail, and the on-cbw-error parameter will decide how this failure is handled. Default 0. (Since 7.1)

6.2

BlockdevOptions (Object)

Options for creating a block device. Many options are available for all block devices, independent of the block driver:

block driver name
the node name of the new node (Since 2.0). This option is required on the top level of blockdev-add. Valid node names start with an alphabetic character and may contain only alphanumeric characters, '-', '.' and '_'. Their maximum length is 31 characters.
discard-related options (default: ignore)
cache-related options
whether the block device should be read-only (default: false). Note that some block drivers support only read-only access, either generally or in certain configurations. In this case, the default value does not work and the option must be specified explicitly.
if true and read-only is false, QEMU may automatically decide not to open the image read-write as requested, but fall back to read-only instead (and switch between the modes later), e.g. depending on whether the image file is writable or whether a writing user is attached to the node (default: false, since 3.1)
detect and optimize zero writes (Since 2.1) (default: off)
force share all permission on added nodes. Requires read-only=true. (Since 2.10)

Remaining options are determined by the block driver.

2.9

BlockdevRef (Alternate)

Reference to a block device.

defines a new block device inline
references the ID of an existing block device

2.9

BlockdevRefOrNull (Alternate)

Reference to a block device.

defines a new block device inline
references the ID of an existing block device. An empty string means that no block device should be referenced. Deprecated; use null instead.
No block device should be referenced (since 2.10)

2.9

blockdev-add (Command)

Creates a new block device.

2.9

-> { "execute": "blockdev-add",
     "arguments": {
          "driver": "qcow2",
          "node-name": "test1",
          "file": {
              "driver": "file",
              "filename": "test.qcow2"
           }
      }
    }
<- { "return": {} }
-> { "execute": "blockdev-add",
     "arguments": {
          "driver": "qcow2",
          "node-name": "node0",
          "discard": "unmap",
          "cache": {
             "direct": true
           },
           "file": {
             "driver": "file",
             "filename": "/tmp/test.qcow2"
           },
           "backing": {
              "driver": "raw",
              "file": {
                 "driver": "file",
                 "filename": "/dev/fdset/4"
               }
           }
       }
     }
<- { "return": {} }

blockdev-reopen (Command)

Reopens one or more block devices using the given set of options. Any option not specified will be reset to its default value regardless of its previous status. If an option cannot be changed or a particular driver does not support reopening then the command will return an error. All devices in the list are reopened in one transaction, so if one of them fails then the whole transaction is cancelled.

The command receives a list of block devices to reopen. For each one of them, the top-level node-name option (from BlockdevOptions) must be specified and is used to select the block device to be reopened. Other node-name options must be either omitted or set to the current name of the appropriate node. This command won't change any node name and any attempt to do it will result in an error.

In the case of options that refer to child nodes, the behavior of this command depends on the value:

1.
A set of options (BlockdevOptions): the child is reopened with the specified set of options.
2.
A reference to the current child: the child is reopened using its existing set of options.
3.
A reference to a different node: the current child is replaced with the specified one.
4.
NULL: the current child (if any) is detached.

Options (1) and (2) are supported in all cases. Option (3) is supported for file and backing, and option (4) for backing only.

Unlike with blockdev-add, the backing option must always be present unless the node being reopened does not have a backing file and its image does not have a default backing file name as part of its metadata.

Not documented

6.1

blockdev-del (Command)

Deletes a block device that has been added using blockdev-add. The command will fail if the node is attached to a device or is otherwise being used.

Name of the graph node to delete.

2.9

-> { "execute": "blockdev-add",
     "arguments": {
          "driver": "qcow2",
          "node-name": "node0",
          "file": {
              "driver": "file",
              "filename": "test.qcow2"
          }
     }
   }
<- { "return": {} }
-> { "execute": "blockdev-del",
     "arguments": { "node-name": "node0" }
   }
<- { "return": {} }

BlockdevCreateOptionsFile (Object)

Driver specific image creation options for file.

Filename for the new image file
Size of the virtual disk in bytes
Preallocation mode for the new image (default: off; allowed values: off, falloc (if CONFIG_POSIX_FALLOCATE), full (if CONFIG_POSIX))
Turn off copy-on-write (valid only on btrfs; default: off)
Extent size hint to add to the image file; 0 for not adding an extent size hint (default: 1 MB, since 5.1)

2.12

BlockdevCreateOptionsGluster (Object)

Driver specific image creation options for gluster.

Where to store the new image file
Size of the virtual disk in bytes
Preallocation mode for the new image (default: off; allowed values: off, falloc (if CONFIG_GLUSTERFS_FALLOCATE), full (if CONFIG_GLUSTERFS_ZEROFILL))

2.12

BlockdevCreateOptionsLUKS (Object)

Driver specific image creation options for LUKS.

Node to create the image format on
Size of the virtual disk in bytes
Preallocation mode for the new image (since: 4.2) (default: off; allowed values: off, metadata, falloc, full)

2.12

BlockdevCreateOptionsNfs (Object)

Driver specific image creation options for NFS.

Where to store the new image file
Size of the virtual disk in bytes

2.12

BlockdevCreateOptionsParallels (Object)

Driver specific image creation options for parallels.

Node to create the image format on
Size of the virtual disk in bytes
Cluster size in bytes (default: 1 MB)

2.12

BlockdevCreateOptionsQcow (Object)

Driver specific image creation options for qcow.

Node to create the image format on
Size of the virtual disk in bytes
File name of the backing file if a backing file should be used
Encryption options if the image should be encrypted

2.12

BlockdevQcow2Version (Enum)

The original QCOW2 format as introduced in qemu 0.10 (version 2)
The extended QCOW2 format as introduced in qemu 1.1 (version 3)

2.12

Qcow2CompressionType (Enum)

Compression type used in qcow2 image file

zlib compression, see http://zlib.net/
zstd compression, see http://github.com/facebook/zstd

5.1

BlockdevCreateOptionsQcow2 (Object)

Driver specific image creation options for qcow2.

Node to create the image format on
Node to use as an external data file in which all guest data is stored so that only metadata remains in the qcow2 file (since: 4.0)
True if the external data file must stay valid as a standalone (read-only) raw image without looking at qcow2 metadata (default: false; since: 4.0)
True to make the image have extended L2 entries (default: false; since 5.2)
Size of the virtual disk in bytes
Compatibility level (default: v3)
File name of the backing file if a backing file should be used
Name of the block driver to use for the backing file
Encryption options if the image should be encrypted
qcow2 cluster size in bytes (default: 65536)
Preallocation mode for the new image (default: off; allowed values: off, falloc, full, metadata)
True if refcounts may be updated lazily (default: off)
Width of reference counts in bits (default: 16)
The image cluster compression method (default: zlib, since 5.1)

2.12

BlockdevCreateOptionsQed (Object)

Driver specific image creation options for qed.

Node to create the image format on
Size of the virtual disk in bytes
File name of the backing file if a backing file should be used
Name of the block driver to use for the backing file
Cluster size in bytes (default: 65536)
L1/L2 table size (in clusters)

2.12

BlockdevCreateOptionsRbd (Object)

Driver specific image creation options for rbd/Ceph.

Where to store the new image file. This location cannot point to a snapshot.
Size of the virtual disk in bytes
RBD object size
Image encryption options. (Since 6.1)

2.12

BlockdevVmdkSubformat (Enum)

Subformat options for VMDK images

Single file image with sparse cluster allocation
Single flat data image and a descriptor file
Data is split into 2GB (per virtual LBA) sparse extent files, in addition to a descriptor file
Data is split into 2GB (per virtual LBA) flat extent files, in addition to a descriptor file
Single file image sparse cluster allocation, optimized for streaming over network.

4.0

BlockdevVmdkAdapterType (Enum)

Adapter type info for VMDK images

Not documented
Not documented
Not documented
Not documented

4.0

BlockdevCreateOptionsVmdk (Object)

Driver specific image creation options for VMDK.

Where to store the new image file. This refers to the image file for monolithcSparse and streamOptimized format, or the descriptor file for other formats.
Size of the virtual disk in bytes
Where to store the data extents. Required for monolithcFlat, twoGbMaxExtentSparse and twoGbMaxExtentFlat formats. For monolithicFlat, only one entry is required; for twoGbMaxExtent* formats, the number of entries required is calculated as extent_number = virtual_size / 2GB. Providing more extents than will be used is an error.
The subformat of the VMDK image. Default: "monolithicSparse".
The path of backing file. Default: no backing file is used.
The adapter type used to fill in the descriptor. Default: ide.
Hardware version. The meaningful options are "4" or "6". Default: "4".
VMware guest tools version. Default: "2147483647" (Since 6.2)
Whether to enable zeroed-grain feature for sparse subformats. Default: false.

4.0

BlockdevCreateOptionsSsh (Object)

Driver specific image creation options for SSH.

Where to store the new image file
Size of the virtual disk in bytes

2.12

BlockdevCreateOptionsVdi (Object)

Driver specific image creation options for VDI.

Node to create the image format on
Size of the virtual disk in bytes
Preallocation mode for the new image (default: off; allowed values: off, metadata)

2.12

BlockdevVhdxSubformat (Enum)

Growing image file
Preallocated fixed-size image file

2.12

BlockdevCreateOptionsVhdx (Object)

Driver specific image creation options for vhdx.

Node to create the image format on
Size of the virtual disk in bytes
Log size in bytes, must be a multiple of 1 MB (default: 1 MB)
Block size in bytes, must be a multiple of 1 MB and not larger than 256 MB (default: automatically choose a block size depending on the image size)
vhdx subformat (default: dynamic)
Force use of payload blocks of type 'ZERO'. Non-standard, but default. Do not set to 'off' when using 'qemu-img convert' with subformat=dynamic.

2.12

BlockdevVpcSubformat (Enum)

Growing image file
Preallocated fixed-size image file

2.12

BlockdevCreateOptionsVpc (Object)

Driver specific image creation options for vpc (VHD).

Node to create the image format on
Size of the virtual disk in bytes
vhdx subformat (default: dynamic)
Force use of the exact byte size instead of rounding to the next size that can be represented in CHS geometry (default: false)

2.12

BlockdevCreateOptions (Object)

Options for creating an image format on a given node.

block driver to create the image format

2.12

blockdev-create (Command)

Starts a job to create an image format on a given node. The job is automatically finalized, but a manual job-dismiss is required.

Identifier for the newly created job.
Options for the image creation.

3.0

BlockdevAmendOptionsLUKS (Object)

Driver specific image amend options for LUKS.

5.1

BlockdevAmendOptionsQcow2 (Object)

Driver specific image amend options for qcow2. For now, only encryption options can be amended

Encryption options to be amended

5.1

BlockdevAmendOptions (Object)

Options for amending an image format

Block driver of the node to amend.

5.1

x-blockdev-amend (Command)

Starts a job to amend format specific options of an existing open block device The job is automatically finalized, but a manual job-dismiss is required.

Identifier for the newly created job.
Name of the block node to work on
Options (driver specific)
Allow unsafe operations, format specific For luks that allows erase of the last active keyslot (permanent loss of data), and replacement of an active keyslot (possible loss of data if IO error happens)

This command is experimental.

5.1

BlockErrorAction (Enum)

An enumeration of action that has been taken when a DISK I/O occurs

error has been ignored
error has been reported to the device
error caused VM to be stopped

2.1

BLOCK_IMAGE_CORRUPTED (Event)

Emitted when a disk image is being marked corrupt. The image can be identified by its device or node name. The 'device' field is always present for compatibility reasons, but it can be empty ("") if the image does not have a device name associated.

device name. This is always present for compatibility reasons, but it can be empty ("") if the image does not have a device name associated.
node name (Since: 2.4)
informative message for human consumption, such as the kind of corruption being detected. It should not be parsed by machine as it is not guaranteed to be stable
if the corruption resulted from an image access, this is the host's access offset into the image
if the corruption resulted from an image access, this is the access size
if set, the image is marked corrupt and therefore unusable after this event and must be repaired (Since 2.2; before, every BLOCK_IMAGE_CORRUPTED event was fatal)

If action is "stop", a STOP event will eventually follow the BLOCK_IO_ERROR event.

<- { "event": "BLOCK_IMAGE_CORRUPTED",
     "data": { "device": "", "node-name": "drive", "fatal": false,
               "msg": "L2 table offset 0x2a2a2a00 unaligned (L1 index: 0)" },
     "timestamp": { "seconds": 1648243240, "microseconds": 906060 } }

1.7

BLOCK_IO_ERROR (Event)

Emitted when a disk I/O error occurs

device name. This is always present for compatibility reasons, but it can be empty ("") if the image does not have a device name associated.
node name. Note that errors may be reported for the root node that is directly attached to a guest device rather than for the node where the error occurred. The node name is not present if the drive is empty. (Since: 2.8)
I/O operation
action that has been taken
true if I/O error was caused due to a no-space condition. This key is only present if query-block's io-status is present, please see query-block documentation for more information (since: 2.2)
human readable string describing the error cause. (This field is a debugging aid for humans, it should not be parsed by applications) (since: 2.2)

If action is "stop", a STOP event will eventually follow the BLOCK_IO_ERROR event

0.13

<- { "event": "BLOCK_IO_ERROR",
     "data": { "device": "ide0-hd1",
               "node-name": "#block212",
               "operation": "write",
               "action": "stop",
               "reason": "No space left on device" },
     "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }

BLOCK_JOB_COMPLETED (Event)

Emitted when a block job has completed

job type
The job identifier. Originally the device name but other values are allowed since QEMU 2.7
maximum progress value
current progress value. On success this is equal to len. On failure this is less than len
rate limit, bytes per second
error message. Only present on failure. This field contains a human-readable error message. There are no semantics other than that streaming has failed and clients should not try to interpret the error string

1.1

<- { "event": "BLOCK_JOB_COMPLETED",
     "data": { "type": "stream", "device": "virtio-disk0",
               "len": 10737418240, "offset": 10737418240,
               "speed": 0 },
     "timestamp": { "seconds": 1267061043, "microseconds": 959568 } }

BLOCK_JOB_CANCELLED (Event)

Emitted when a block job has been cancelled

job type
The job identifier. Originally the device name but other values are allowed since QEMU 2.7
maximum progress value
current progress value. On success this is equal to len. On failure this is less than len
rate limit, bytes per second

1.1

<- { "event": "BLOCK_JOB_CANCELLED",
     "data": { "type": "stream", "device": "virtio-disk0",
               "len": 10737418240, "offset": 134217728,
               "speed": 0 },
     "timestamp": { "seconds": 1267061043, "microseconds": 959568 } }

BLOCK_JOB_ERROR (Event)

Emitted when a block job encounters an error

The job identifier. Originally the device name but other values are allowed since QEMU 2.7
I/O operation
action that has been taken

1.3

<- { "event": "BLOCK_JOB_ERROR",
     "data": { "device": "ide0-hd1",
               "operation": "write",
               "action": "stop" },
     "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }

BLOCK_JOB_READY (Event)

Emitted when a block job is ready to complete

job type
The job identifier. Originally the device name but other values are allowed since QEMU 2.7
maximum progress value
current progress value. On success this is equal to len. On failure this is less than len
rate limit, bytes per second

The "ready to complete" status is always reset by a BLOCK_JOB_ERROR event

1.3

<- { "event": "BLOCK_JOB_READY",
     "data": { "device": "drive0", "type": "mirror", "speed": 0,
               "len": 2097152, "offset": 2097152 },
     "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }

BLOCK_JOB_PENDING (Event)

Emitted when a block job is awaiting explicit authorization to finalize graph changes via block-job-finalize. If this job is part of a transaction, it will not emit this event until the transaction has converged first.

job type
The job identifier.

2.12

<- { "event": "BLOCK_JOB_PENDING",
     "data": { "type": "mirror", "id": "backup_1" },
     "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }

PreallocMode (Enum)

Preallocation mode of QEMU image file

no preallocation
preallocate only for metadata
like full preallocation but allocate disk space by posix_fallocate() rather than writing data.
preallocate all data by writing it to the device to ensure disk space is really available. This data may or may not be zero, depending on the image format and storage. full preallocation also sets up metadata correctly.

2.2

BLOCK_WRITE_THRESHOLD (Event)

Emitted when writes on block device reaches or exceeds the configured write threshold. For thin-provisioned devices, this means the device should be extended to avoid pausing for disk exhaustion. The event is one shot. Once triggered, it needs to be re-registered with another block-set-write-threshold command.

graph node name on which the threshold was exceeded.
amount of data which exceeded the threshold, in bytes.
last configured threshold, in bytes.

2.3

block-set-write-threshold (Command)

Change the write threshold for a block drive. An event will be delivered if a write to this block drive crosses the configured threshold. The threshold is an offset, thus must be non-negative. Default is no write threshold. Setting the threshold to zero disables it.

This is useful to transparently resize thin-provisioned drives without the guest OS noticing.

graph node name on which the threshold must be set.
configured threshold for the block device, bytes. Use 0 to disable the threshold.

2.3

-> { "execute": "block-set-write-threshold",
     "arguments": { "node-name": "mydev",
                    "write-threshold": 17179869184 } }
<- { "return": {} }

x-blockdev-change (Command)

Dynamically reconfigure the block driver state graph. It can be used to add, remove, insert or replace a graph node. Currently only the Quorum driver implements this feature to add or remove its child. This is useful to fix a broken quorum child.

If node is specified, it will be inserted under parent. child may not be specified in this case. If both parent and child are specified but node is not, child will be detached from parent.

the id or name of the parent node.
the name of a child under the given parent node.
the name of the node that will be added.

This command is experimental, and its API is not stable. It does not support all kinds of operations, all kinds of children, nor all block drivers.

FIXME Removing children from a quorum node means introducing gaps in the child indices. This cannot be represented in the 'children' list of BlockdevOptionsQuorum, as returned by .bdrv_refresh_filename().

Warning: The data in a new quorum child MUST be consistent with that of the rest of the array.

2.7

1. Add a new node to a quorum
-> { "execute": "blockdev-add",
     "arguments": {
         "driver": "raw",
         "node-name": "new_node",
         "file": { "driver": "file",
                   "filename": "test.raw" } } }
<- { "return": {} }
-> { "execute": "x-blockdev-change",
     "arguments": { "parent": "disk1",
                    "node": "new_node" } }
<- { "return": {} }
2. Delete a quorum's node
-> { "execute": "x-blockdev-change",
     "arguments": { "parent": "disk1",
                    "child": "children.1" } }
<- { "return": {} }

x-blockdev-set-iothread (Command)

Move node and its children into the iothread. If iothread is null then move node and its children into the main loop.

The node must not be attached to a BlockBackend.

the name of the block driver node
the name of the IOThread object or null for the main loop
true if the node and its children should be moved when a BlockBackend is already attached

This command is experimental and intended for test cases that need control over IOThreads only.

2.12

1. Move a node into an IOThread
-> { "execute": "x-blockdev-set-iothread",
     "arguments": { "node-name": "disk1",
                    "iothread": "iothread0" } }
<- { "return": {} }
2. Move a node into the main loop
-> { "execute": "x-blockdev-set-iothread",
     "arguments": { "node-name": "disk1",
                    "iothread": null } }
<- { "return": {} }

QuorumOpType (Enum)

An enumeration of the quorum operation types

read operation
write operation
flush operation

2.6

QUORUM_FAILURE (Event)

Emitted by the Quorum block driver if it fails to establish a quorum

device name if defined else node name
number of the first sector of the failed read operation
failed read operation sector count

This event is rate-limited.

2.0

<- { "event": "QUORUM_FAILURE",
     "data": { "reference": "usr1", "sector-num": 345435, "sectors-count": 5 },
     "timestamp": { "seconds": 1344522075, "microseconds": 745528 } }

QUORUM_REPORT_BAD (Event)

Emitted to report a corruption of a Quorum file

quorum operation type (Since 2.6)
error message. Only present on failure. This field contains a human-readable error message. There are no semantics other than that the block layer reported an error and clients should not try to interpret the error string.
the graph node name of the block driver state
number of the first sector of the failed read operation
failed read operation sector count

This event is rate-limited.

2.0

1. Read operation
<- { "event": "QUORUM_REPORT_BAD",
     "data": { "node-name": "node0", "sector-num": 345435, "sectors-count": 5,
               "type": "read" },
     "timestamp": { "seconds": 1344522075, "microseconds": 745528 } }
2. Flush operation
<- { "event": "QUORUM_REPORT_BAD",
     "data": { "node-name": "node0", "sector-num": 0, "sectors-count": 2097120,
               "type": "flush", "error": "Broken pipe" },
     "timestamp": { "seconds": 1456406829, "microseconds": 291763 } }

BlockdevSnapshotInternal (Object)

the device name or node-name of a root node to generate the snapshot from
the name of the internal snapshot to be created

In transaction, if name is empty, or any snapshot matching name exists, the operation will fail. Only some image formats support it, for example, qcow2, and rbd.

1.7

blockdev-snapshot-internal-sync (Command)

Synchronously take an internal snapshot of a block device, when the format of the image used supports it. If the name is an empty string, or a snapshot with name already exists, the operation will fail.

For the arguments, see the documentation of BlockdevSnapshotInternal.

  • nothing on success
  • If device is not a valid block device, GenericError
  • If any snapshot matching name exists, or name is empty, GenericError
  • If the format of the image used does not support it, GenericError

1.7

-> { "execute": "blockdev-snapshot-internal-sync",
     "arguments": { "device": "ide-hd0",
                    "name": "snapshot0" }
   }
<- { "return": {} }

blockdev-snapshot-delete-internal-sync (Command)

Synchronously delete an internal snapshot of a block device, when the format of the image used support it. The snapshot is identified by name or id or both. One of the name or id is required. Return SnapshotInfo for the successfully deleted snapshot.

the device name or node-name of a root node to delete the snapshot from
optional the snapshot's ID to be deleted
optional the snapshot's name to be deleted

  • SnapshotInfo on success
  • If device is not a valid block device, GenericError
  • If snapshot not found, GenericError
  • If the format of the image used does not support it, GenericError
  • If id and name are both not specified, GenericError

1.7

-> { "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,
                   "icount": 220414
     }
   }

DummyBlockCoreForceArrays (Object)

Not used by QMP; hack to let us use BlockGraphInfoList internally

Not documented

8.0

NbdServerOptions (Object)

Keep this type consistent with the nbd-server-start arguments. The only intended difference is using SocketAddress instead of SocketAddressLegacy.

Address on which to listen.
ID of the TLS credentials object (since 2.6).
ID of the QAuthZ authorization object used to validate the client's x509 distinguished name. This object is is only resolved at time of use, so can be deleted and recreated on the fly while the NBD server is active. If missing, it will default to denying access (since 4.0).
The maximum number of connections to allow at the same time, 0 for unlimited. Setting this to 1 also stops the server from advertising multiple client support (since 5.2; default: 0)

4.2

nbd-server-start (Command)

Start an NBD server listening on the given host and port. Block devices can then be exported using nbd-server-add. The NBD server will present them as named exports; for example, another QEMU instance could refer to them as "nbd:HOST:PORT:exportname=NAME".

Keep this type consistent with the NbdServerOptions type. The only intended difference is using SocketAddressLegacy instead of SocketAddress.

Address on which to listen.
ID of the TLS credentials object (since 2.6).
ID of the QAuthZ authorization object used to validate the client's x509 distinguished name. This object is is only resolved at time of use, so can be deleted and recreated on the fly while the NBD server is active. If missing, it will default to denying access (since 4.0).
The maximum number of connections to allow at the same time, 0 for unlimited. Setting this to 1 also stops the server from advertising multiple client support (since 5.2; default: 0).

error if the server is already running.

1.3

BlockExportOptionsNbdBase (Object)

An NBD block export (common options shared between nbd-server-add and the NBD branch of block-export-add).

Export name. If unspecified, the device parameter is used as the export name. (Since 2.12)
Free-form description of the export, up to 4096 bytes. (Since 5.0)

5.0

BlockExportOptionsNbd (Object)

An NBD block export (distinct options used in the NBD branch of block-export-add).

Also export each of the named dirty bitmaps reachable from device, so the NBD client can use NBD_OPT_SET_META_CONTEXT with the metadata context name "qemu:dirty-bitmap:BITMAP" to inspect each bitmap. Since 7.1 bitmap may be specified by node/name pair.
Also export the allocation depth map for device, so the NBD client can use NBD_OPT_SET_META_CONTEXT with the metadata context name "qemu:allocation-depth" to inspect allocation details. (since 5.2)

5.2

BlockExportOptionsVhostUserBlk (Object)

A vhost-user-blk block export.

The vhost-user socket on which to listen. Both 'unix' and 'fd' SocketAddress types are supported. Passed fds must be UNIX domain sockets.
Logical block size in bytes. Defaults to 512 bytes.
Number of request virtqueues. Must be greater than 0. Defaults to 1.

5.2

FuseExportAllowOther (Enum)

Possible allow_other modes for FUSE exports.

Do not pass allow_other as a mount option.
Pass allow_other as a mount option.
Try mounting with allow_other first, and if that fails, retry without allow_other.

6.1

BlockExportOptionsFuse (Object)

Options for exporting a block graph node on some (file) mountpoint as a raw image.

Path on which to export the block device via FUSE. This must point to an existing regular file.
Whether writes beyond the EOF should grow the block node accordingly. (default: false)
If this is off, only qemu's user is allowed access to this export. That cannot be changed even with chmod or chown. Enabling this option will allow other users access to the export with the FUSE mount option "allow_other". Note that using allow_other as a non-root user requires user_allow_other to be enabled in the global fuse.conf configuration file. In auto mode (the default), the FUSE export driver will first attempt to mount the export with allow_other, and if that fails, try again without. (since 6.1; default: auto)

6.0

CONFIG_FUSE

BlockExportOptionsVduseBlk (Object)

A vduse-blk block export.

the name of VDUSE device (must be unique across the host).
the number of virtqueues. Defaults to 1.
the size of virtqueue. Defaults to 256.
Logical block size in bytes. Range [512, PAGE_SIZE] and must be power of 2. Defaults to 512 bytes.
the serial number of virtio block device. Defaults to empty string.

7.1

NbdServerAddOptions (Object)

An NBD block export, per legacy nbd-server-add command.

The device name or node name of the node to be exported
Whether clients should be able to write to the device via the NBD connection (default false).
Also export a single dirty bitmap reachable from device, so the NBD client can use NBD_OPT_SET_META_CONTEXT with the metadata context name "qemu:dirty-bitmap:BITMAP" to inspect the bitmap (since 4.0).

5.0

nbd-server-add (Command)

Export a block node to QEMU's embedded NBD server.

The export name will be used as the id for the resulting block export.

This command is deprecated. Use block-export-add instead.

error if the server is not running, or export with the same name already exists.

1.3

BlockExportRemoveMode (Enum)

Mode for removing a block export.

Remove export if there are no existing connections, fail otherwise.
Drop all connections immediately and remove export.

Potential additional modes to be added in the future:

hide: Just hide export from new clients, leave existing connections as is. Remove export after all clients are disconnected.

soft: Hide export from new clients, answer with ESHUTDOWN for all further requests from existing clients.

2.12

nbd-server-remove (Command)

Remove NBD export by name.

Block export id.
Mode of command operation. See BlockExportRemoveMode description. Default is 'safe'.

This command is deprecated. Use block-export-del instead.

error if

  • the server is not running
  • export is not found
  • mode is 'safe' and there are existing connections

2.12

nbd-server-stop (Command)

Stop QEMU's embedded NBD server, and unregister all devices previously added via nbd-server-add.

1.3

BlockExportType (Enum)

An enumeration of block export types

NBD export
vhost-user-blk export (since 5.2)
FUSE export (since: 6.0)
vduse-blk export (since 7.1)

4.2

BlockExportOptions (Object)

Describes a block export, i.e. how single node should be exported on an external interface.

A unique identifier for the block export (across all export types)
The node name of the block node to be exported (since: 5.2)
True if clients should be able to write to the export (default false)
If true, caches are flushed after every write request to the export before completion is signalled. (since: 5.2; default: false)
The name of the iothread object where the export will run. The default is to use the thread currently associated with the block node. (since: 5.2)
True prevents the block node from being moved to another thread while the export is active. If true and iothread is given, export creation fails if the block node cannot be moved to the iothread. The default is false. (since: 5.2)
Not documented

4.2

block-export-add (Command)

Creates a new block export.

5.2

block-export-del (Command)

Request to remove a block export. This drops the user's reference to the export, but the export may still stay around after this command returns until the shutdown of the export has completed.

Block export id.
Mode of command operation. See BlockExportRemoveMode description. Default is 'safe'.

Error if the export is not found or mode is 'safe' and the export is still in use (e.g. by existing client connections)

5.2

BLOCK_EXPORT_DELETED (Event)

Emitted when a block export is removed and its id can be reused.

Block export id.

5.2

BlockExportInfo (Object)

Information about a single block export.

The unique identifier for the block export
The block export type
The node name of the block node that is exported
True if the export is shutting down (e.g. after a block-export-del command, but before the shutdown has completed)

5.2

query-block-exports (Command)

A list of BlockExportInfo describing all block exports

5.2

ChardevInfo (Object)

Information about a character device.

the label of the character device
the filename of the character device
shows whether the frontend device attached to this backend (e.g. with the chardev=... option) is in open or closed state (since 2.1)

filename is encoded using the QEMU command line character device encoding. See the QEMU man page for details.

0.14

query-chardev (Command)

Returns information about current character devices.

a list of ChardevInfo

0.14

-> { "execute": "query-chardev" }
<- {
      "return": [
         {
            "label": "charchannel0",
            "filename": "unix:/var/lib/libvirt/qemu/seabios.rhel6.agent,server=on",
            "frontend-open": false
         },
         {
            "label": "charmonitor",
            "filename": "unix:/var/lib/libvirt/qemu/seabios.rhel6.monitor,server=on",
            "frontend-open": true
         },
         {
            "label": "charserial0",
            "filename": "pty:/dev/pts/2",
            "frontend-open": true
         }
      ]
   }

ChardevBackendInfo (Object)

Information about a character device backend

The backend name

2.0

query-chardev-backends (Command)

Returns information about character device backends.

a list of ChardevBackendInfo

2.0

-> { "execute": "query-chardev-backends" }
<- {
      "return":[
         {
            "name":"udp"
         },
         {
            "name":"tcp"
         },
         {
            "name":"unix"
         },
         {
            "name":"spiceport"
         }
      ]
   }

DataFormat (Enum)

An enumeration of data format.

Data is a UTF-8 string (RFC 3629)
Data is Base64 encoded binary (RFC 3548)

1.4

ringbuf-write (Command)

Write to a ring buffer character device.

the ring buffer character device name
data to write
data encoding (default 'utf8').
  • base64: data must be base64 encoded text. Its binary decoding gets written.
  • utf8: data's UTF-8 encoding is written
  • data itself is always Unicode regardless of format, like any other string.

Nothing on success

1.4

-> { "execute": "ringbuf-write",
     "arguments": { "device": "foo",
                    "data": "abcdefgh",
                    "format": "utf8" } }
<- { "return": {} }

ringbuf-read (Command)

Read from a ring buffer character device.

the ring buffer character device name
how many bytes to read at most
data encoding (default 'utf8').
  • base64: the data read is returned in base64 encoding.
  • utf8: the data read is interpreted as UTF-8. Bug: can screw up when the buffer contains invalid UTF-8 sequences, NUL characters, after the ring buffer lost data, and when reading stops because the size limit is reached.
  • The return value is always Unicode regardless of format, like any other string.

data read from the device

1.4

-> { "execute": "ringbuf-read",
     "arguments": { "device": "foo",
                    "size": 1000,
                    "format": "utf8" } }
<- { "return": "abcdefgh" }

ChardevCommon (Object)

Configuration shared across all chardev backends

The name of a logfile to save output
true to append instead of truncate (default to false to truncate)

2.6

ChardevFile (Object)

Configuration info for file chardevs.

The name of the input file
The name of the output file
Open the file in append mode (default false to truncate) (Since 2.6)

1.4

ChardevHostdev (Object)

Configuration info for device and pipe chardevs.

The name of the special file for the device, i.e. /dev/ttyS0 on Unix or COM1: on Windows

1.4

ChardevSocket (Object)

Configuration info for (stream) socket chardevs.

socket address to listen on (server=true) or connect to (server=false)
the ID of the TLS credentials object (since 2.6)
the ID of the QAuthZ authorization object against which the client's x509 distinguished name will be validated. This object is only resolved at time of use, so can be deleted and recreated on the fly while the chardev server is active. If missing, it will default to denying access (since 4.0)
create server socket (default: true)
wait for incoming connection on server sockets (default: false). Silently ignored with server: false. This use is deprecated.
set TCP_NODELAY socket option (default: false)
enable telnet protocol on server sockets (default: false)
enable tn3270 protocol on server sockets (default: false) (Since: 2.10)
enable websocket protocol on server sockets (default: false) (Since: 3.1)
For a client socket, if a socket is disconnected, then attempt a reconnect after the given number of seconds. Setting this to zero disables this function. (default: 0) (Since: 2.2)

1.4

ChardevUdp (Object)

Configuration info for datagram socket chardevs.

remote address
local address

1.5

ChardevMux (Object)

Configuration info for mux chardevs.

name of the base chardev.

1.5

ChardevStdio (Object)

Configuration info for stdio chardevs.

Allow signals (such as SIGINT triggered by ^C) be delivered to qemu. Default: true.

1.5

ChardevSpiceChannel (Object)

Configuration info for spice vm channel chardevs.

kind of channel (for example vdagent).

1.5

CONFIG_SPICE

ChardevSpicePort (Object)

Configuration info for spice port chardevs.

name of the channel (see docs/spice-port-fqdn.txt)

1.5

CONFIG_SPICE

ChardevDBus (Object)

Configuration info for DBus chardevs.

name of the channel (following docs/spice-port-fqdn.txt)

7.0

CONFIG_DBUS_DISPLAY

ChardevVC (Object)

Configuration info for virtual console chardevs.

console width, in pixels
console height, in pixels
console width, in chars
console height, in chars

the options are only effective when the VNC or SDL graphical display backend is active. They are ignored with the GTK, Spice, VNC and D-Bus display backends.

1.5

ChardevRingbuf (Object)

Configuration info for ring buffer chardevs.

ring buffer size, must be power of two, default is 65536

1.5

ChardevQemuVDAgent (Object)

Configuration info for qemu vdagent implementation.

enable/disable mouse, default is enabled.
enable/disable clipboard, default is disabled.

6.1

CONFIG_SPICE_PROTOCOL

ChardevBackendKind (Enum)

Since 1.5
Since 1.5
Since 1.5
Since 1.5
Since 2.9
Since 1.5
Since 2.2
Since 1.5
Since 1.5
Since 1.5
Since 1.5
Since 6.1
Since 7.0
v1.5
Since 1.6
Since 1.5
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented

1.4

ChardevFileWrapper (Object)

Not documented

1.4

ChardevHostdevWrapper (Object)

Not documented

1.4

ChardevSocketWrapper (Object)

Not documented

1.4

ChardevUdpWrapper (Object)

Not documented

1.5

ChardevCommonWrapper (Object)

Not documented

2.6

ChardevMuxWrapper (Object)

Not documented

1.5

ChardevStdioWrapper (Object)

Not documented

1.5

ChardevSpiceChannelWrapper (Object)

Not documented

1.5

CONFIG_SPICE

ChardevSpicePortWrapper (Object)

Not documented

1.5

CONFIG_SPICE

ChardevQemuVDAgentWrapper (Object)

Not documented

6.1

CONFIG_SPICE_PROTOCOL

ChardevDBusWrapper (Object)

Not documented

7.0

CONFIG_DBUS_DISPLAY

ChardevVCWrapper (Object)

Not documented

1.5

ChardevRingbufWrapper (Object)

Not documented

1.5

ChardevBackend (Object)

Configuration info for the new chardev backend.

Not documented

1.4

ChardevReturn (Object)

Return info about the chardev backend just created.

name of the slave pseudoterminal device, present if and only if a chardev of type 'pty' was created

1.4

chardev-add (Command)

Add a character device backend

the chardev's ID, must be unique
backend type and parameters

ChardevReturn.

1.4

-> { "execute" : "chardev-add",
     "arguments" : { "id" : "foo",
                     "backend" : { "type" : "null", "data" : {} } } }
<- { "return": {} }
-> { "execute" : "chardev-add",
     "arguments" : { "id" : "bar",
                     "backend" : { "type" : "file",
                                   "data" : { "out" : "/tmp/bar.log" } } } }
<- { "return": {} }
-> { "execute" : "chardev-add",
     "arguments" : { "id" : "baz",
                     "backend" : { "type" : "pty", "data" : {} } } }
<- { "return": { "pty" : "/dev/pty/42" } }

chardev-change (Command)

Change a character device backend

the chardev's ID, must exist
new backend type and parameters

ChardevReturn.

2.10

-> { "execute" : "chardev-change",
     "arguments" : { "id" : "baz",
                     "backend" : { "type" : "pty", "data" : {} } } }
<- { "return": { "pty" : "/dev/pty/42" } }
-> {"execute" : "chardev-change",
    "arguments" : {
        "id" : "charchannel2",
        "backend" : {
            "type" : "socket",
            "data" : {
                "addr" : {
                    "type" : "unix" ,
                    "data" : {
                        "path" : "/tmp/charchannel2.socket"
                    }
                 },
                 "server" : true,
                 "wait" : false }}}}
<- {"return": {}}

chardev-remove (Command)

Remove a character device backend

the chardev's ID, must exist and not be in use

Nothing on success

1.4

-> { "execute": "chardev-remove", "arguments": { "id" : "foo" } }
<- { "return": {} }

chardev-send-break (Command)

Send a break to a character device

the chardev's ID, must exist

Nothing on success

2.10

-> { "execute": "chardev-send-break", "arguments": { "id" : "foo" } }
<- { "return": {} }

VSERPORT_CHANGE (Event)

Emitted when the guest opens or closes a virtio-serial port.

device identifier of the virtio-serial port
true if the guest has opened the virtio-serial port

This event is rate-limited.

2.1

<- { "event": "VSERPORT_CHANGE",
     "data": { "id": "channel0", "open": true },
     "timestamp": { "seconds": 1401385907, "microseconds": 422329 } }

QAuthZListPolicy (Enum)

The authorization policy result

deny access
allow access

4.0

QAuthZListFormat (Enum)

The authorization policy match format

an exact string match
string with ? and * shell wildcard support

4.0

QAuthZListRule (Object)

A single authorization rule.

a string or glob to match against a user identity
the result to return if match evaluates to true
the format of the match rule (default 'exact')

4.0

AuthZListProperties (Object)

Properties for authz-list objects.

Default policy to apply when no rule matches (default: deny)
Authorization rules based on matching user

4.0

AuthZListFileProperties (Object)

Properties for authz-listfile objects.

File name to load the configuration from. The file must contain valid JSON for AuthZListProperties.
If true, inotify is used to monitor the file, automatically reloading changes. If an error occurs during reloading, all authorizations will fail until the file is next successfully loaded. (default: true if the binary was built with CONFIG_INOTIFY1, false otherwise)

4.0

AuthZPAMProperties (Object)

Properties for authz-pam objects.

PAM service name to use for authorization

4.0

AuthZSimpleProperties (Object)

Properties for authz-simple objects.

Identifies the allowed user. Its format depends on the network service that authorization object is associated with. For authorizing based on TLS x509 certificates, the identity must be the x509 distinguished name.

4.0

Abort (Object)

This action can be used to test transaction failure.

1.6

ActionCompletionMode (Enum)

An enumeration of Transactional completion modes.

Do not attempt to cancel any other Actions if any Actions fail after the Transaction request succeeds. All Actions that can complete successfully will do so without waiting on others. This is the default.
If any Action fails after the Transaction succeeds, cancel all Actions. Actions do not complete until all Actions are ready to complete. May be rejected by Actions that do not support this completion mode.

2.5

TransactionActionKind (Enum)

Since 1.6
Since 2.5
Since 4.2
Since 2.5
Since 4.0
Since 4.0
Since 4.0
Since 2.3
Since 2.5
Since 1.7
since 1.1
Since 1.6

Member drive-backup is deprecated. Use member blockdev-backup instead.

1.1

AbortWrapper (Object)

Not documented

1.6

BlockDirtyBitmapAddWrapper (Object)

Not documented

2.5

BlockDirtyBitmapWrapper (Object)

Not documented

2.5

BlockDirtyBitmapMergeWrapper (Object)

Not documented

4.0

BlockdevBackupWrapper (Object)

Not documented

2.3

BlockdevSnapshotWrapper (Object)

Not documented

2.5

BlockdevSnapshotInternalWrapper (Object)

Not documented

1.7

BlockdevSnapshotSyncWrapper (Object)

Not documented

1.1

DriveBackupWrapper (Object)

Not documented

1.6

TransactionAction (Object)

A discriminated record of operations that can be performed with transaction.

Not documented

1.1

TransactionProperties (Object)

Optional arguments to modify the behavior of a Transaction.

Controls how jobs launched asynchronously by Actions will complete or fail as a group. See ActionCompletionMode for details.

2.5

transaction (Command)

Executes a number of transactionable QMP commands atomically. If any operation fails, then the entire set of actions will be abandoned and the appropriate error returned.

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, and rbd,

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.

List of TransactionAction; information needed for the respective operations.
structure of additional options to control the execution of the transaction. See TransactionProperties for additional detail.

nothing on success

Errors depend on the operations of the transaction

The transaction aborts on the first failure. Therefore, there will be information on only one failed operation returned in an error condition, and subsequent actions will not have been attempted.

1.1

-> { "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": {} }

qmp_capabilities (Command)

Enable QMP capabilities.

Arguments:

An optional list of QMPCapability values to enable. The client must not enable any capability that is not mentioned in the QMP greeting message. If the field is not provided, it means no QMP capabilities will be enabled. (since 2.12)

-> { "execute": "qmp_capabilities",
     "arguments": { "enable": [ "oob" ] } }
<- { "return": {} }

This command is valid exactly when first connecting: it must be issued before any other command will be accepted, and will fail once the monitor is accepting other commands. (see qemu docs/interop/qmp-spec.rst)

The QMP client needs to explicitly enable QMP capabilities, otherwise all the QMP capabilities will be turned off by default.

0.13

QMPCapability (Enum)

Enumeration of capabilities to be advertised during initial client connection, used for agreeing on particular QMP extension behaviors.

QMP ability to support out-of-band requests. (Please refer to qmp-spec.rst for more information on OOB)

2.12

VersionTriple (Object)

A three-part version number.

The major version number.
The minor version number.
The micro version number.

2.4

VersionInfo (Object)

A description of QEMU's version.

The version of QEMU. By current convention, a micro version of 50 signifies a development branch. A micro version greater than or equal to 90 signifies a release candidate for the next minor version. A micro version of less than 50 signifies a stable release.
QEMU will always set this field to an empty string. Downstream versions of QEMU should set this to a non-empty string. The exact format depends on the downstream however it highly recommended that a unique name is used.

0.14

query-version (Command)

Returns the current version of QEMU.

A VersionInfo object describing the current version of QEMU.

0.14

-> { "execute": "query-version" }
<- {
      "return":{
         "qemu":{
            "major":0,
            "minor":11,
            "micro":5
         },
         "package":""
      }
   }

CommandInfo (Object)

Information about a QMP command

The command name

0.14

query-commands (Command)

Return a list of supported QMP commands by this server

A list of CommandInfo for all supported commands

0.14

-> { "execute": "query-commands" }
<- {
     "return":[
        {
           "name":"query-balloon"
        },
        {
           "name":"system_powerdown"
        }
     ]
   }

This example has been shortened as the real response is too long.

quit (Command)

This command will cause the QEMU process to exit gracefully. While every attempt is made to send the QMP response before terminating, this is not guaranteed. When using this interface, a premature EOF would not be unexpected.

0.14

-> { "execute": "quit" }
<- { "return": {} }

MonitorMode (Enum)

An enumeration of monitor modes.

HMP monitor (human-oriented command line interface)
QMP monitor (JSON-based machine interface)

5.0

MonitorOptions (Object)

Options to be used for adding a new monitor.

Name of the monitor
Selects the monitor mode (default: readline in the system emulator, control in qemu-storage-daemon)
Enables pretty printing (QMP only)
Name of a character device to expose the monitor on

5.0

query-qmp-schema (Command)

Command query-qmp-schema exposes the QMP wire ABI as an array of SchemaInfo. This lets QMP clients figure out what commands and events are available in this QEMU, and their parameters and results.

However, the SchemaInfo can't reflect all the rules and restrictions that apply to QMP. It's interface introspection (figuring out what's there), not interface specification. The specification is in the QAPI schema.

Furthermore, while we strive to keep the QMP wire format backwards-compatible across qemu versions, the introspection output is not guaranteed to have the same stability. For example, one version of qemu may list an object member as an optional non-variant, while another lists the same member only through the object's variants; or the type of a member may change from a generic string into a specific enum or from one specific type into an alternate that includes the original type alongside something else.

array of SchemaInfo, where each element describes an entity in the ABI: command, event, type, ...

The order of the various SchemaInfo is unspecified; however, all names are guaranteed to be unique (no name will be duplicated with different meta-types).

the QAPI schema is also used to help define internal interfaces, by defining QAPI types. These are not part of the QMP wire ABI, and therefore not returned by this command.

2.5

SchemaMetaType (Enum)

This is a SchemaInfo's meta type, i.e. the kind of entity it describes.

a predefined type such as 'int' or 'bool'.
an enumeration type
an array type
an object type (struct or union)
an alternate type
a QMP command
a QMP event

2.5

SchemaInfo (Object)

the entity's name, inherited from base. The SchemaInfo is always referenced by this name. Commands and events have the name defined in the QAPI schema. Unlike command and event names, type names are not part of the wire ABI. Consequently, type names are meaningless strings here, although they are still guaranteed unique regardless of meta-type.
the entity's meta type, inherited from base.
names of features associated with the entity, in no particular order. (since 4.1 for object types, 4.2 for commands, 5.0 for the rest)

Additional members depend on the value of meta-type.

2.5

SchemaInfoBuiltin (Object)

Additional SchemaInfo members for meta-type 'builtin'.

the JSON type used for this type on the wire.

2.5

JSONType (Enum)

The four primitive and two structured types according to RFC 8259 section 1, plus 'int' (split off 'number'), plus the obvious top type 'value'.

Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented
Not documented

2.5

SchemaInfoEnum (Object)

Additional SchemaInfo members for meta-type 'enum'.

the enum type's members, in no particular order (since 6.2).
the enumeration type's member names, in no particular order. Redundant with members. Just for backward compatibility.

Member values is deprecated. Use members instead.

Values of this type are JSON string on the wire.

2.5

SchemaInfoEnumMember (Object)

An object member.

the member's name, as defined in the QAPI schema.
names of features associated with the member, in no particular order.

6.2

SchemaInfoArray (Object)

Additional SchemaInfo members for meta-type 'array'.

the array type's element type.

Values of this type are JSON array on the wire.

2.5

SchemaInfoObject (Object)

Additional SchemaInfo members for meta-type 'object'.

the object type's (non-variant) members, in no particular order.
the name of the member serving as type tag. An element of members with this name must exist.
variant members, i.e. additional members that depend on the type tag's value. Present exactly when tag is present. The variants are in no particular order, and may even differ from the order of the values of the enum type of the tag.

Values of this type are JSON object on the wire.

2.5

SchemaInfoObjectMember (Object)

An object member.

the member's name, as defined in the QAPI schema.
the name of the member's type.
default when used as command parameter. If absent, the parameter is mandatory. If present, the value must be null. The parameter is optional, and behavior when it's missing is not specified here. Future extension: if present and non-null, the parameter is optional, and defaults to this value.
names of features associated with the member, in no particular order. (since 5.0)

2.5

SchemaInfoObjectVariant (Object)

The variant members for a value of the type tag.

a value of the type tag.
the name of the object type that provides the variant members when the type tag has value case.

2.5

SchemaInfoAlternate (Object)

Additional SchemaInfo members for meta-type 'alternate'.

the alternate type's members, in no particular order. The members' wire encoding is distinct, see docs/devel/qapi-code-gen.txt section Alternate types.

On the wire, this can be any of the members.

2.5

SchemaInfoAlternateMember (Object)

An alternate member.

the name of the member's type.

2.5

SchemaInfoCommand (Object)

Additional SchemaInfo members for meta-type 'command'.

the name of the object type that provides the command's parameters.
the name of the command's result type.
whether the command allows out-of-band execution, defaults to false (Since: 2.12)

2.5

SchemaInfoEvent (Object)

Additional SchemaInfo members for meta-type 'event'.

the name of the object type that provides the event's parameters.

2.5

ObjectPropertyInfo (Object)

the name of the property
the type of the property. This will typically come in one of four forms:
1.
A primitive type such as 'u8', 'u16', 'bool', 'str', or 'double'. These types are mapped to the appropriate JSON type.
2.
A child type in the form 'child<subtype>' where subtype is a qdev device type name. Child properties create the composition tree.
3.
A link type in the form 'link<subtype>' where subtype is a qdev device type name. Link properties form the device model graph.
if specified, the description of the property.
the default value, if any (since 5.0)

1.2

qom-list (Command)

This command will list any properties of a object given a path in the object model.

the path within the object model. See qom-get for a description of this parameter.

a list of ObjectPropertyInfo that describe the properties of the object.

1.2

-> { "execute": "qom-list",
     "arguments": { "path": "/chardevs" } }
<- { "return": [ { "name": "type", "type": "string" },
                 { "name": "parallel0", "type": "child<chardev-vc>" },
                 { "name": "serial0", "type": "child<chardev-vc>" },
                 { "name": "mon0", "type": "child<chardev-stdio>" } ] }

qom-get (Command)

This command will get a property from a object model path and return the value.

The path within the object model. There are two forms of supported paths--absolute and partial paths.

Absolute paths are derived from the root object and can follow child<> or link<> properties. Since they can follow link<> properties, they can be arbitrarily long. Absolute paths look like absolute filenames and are prefixed with a leading slash.

Partial paths look like relative filenames. They do not begin with a prefix. The matching rules for partial paths are subtle but designed to make specifying objects easy. At each level of the composition tree, the partial path is matched as an absolute path. The first match is not returned. At least two matches are searched for. A successful result is only returned if only one match is found. If more than one match is found, a flag is return to indicate that the match was ambiguous.

The property name to read

The property value. The type depends on the property type. child<> and link<> properties are returned as #str pathnames. All integer property types (u8, u16, etc) are returned as #int.

1.2

1. Use absolute path
-> { "execute": "qom-get",
     "arguments": { "path": "/machine/unattached/device[0]",
                    "property": "hotplugged" } }
<- { "return": false }
2. Use partial path
-> { "execute": "qom-get",
     "arguments": { "path": "unattached/sysbus",
                    "property": "type" } }
<- { "return": "System" }

qom-set (Command)

This command will set a property from a object model path.

see qom-get for a description of this parameter
the property name to set
a value who's type is appropriate for the property type. See qom-get for a description of type mapping.

1.2

-> { "execute": "qom-set",
     "arguments": { "path": "/machine",
                    "property": "graphics",
                    "value": false } }
<- { "return": {} }

ObjectTypeInfo (Object)

This structure describes a search result from qom-list-types

the type name found in the search
the type is abstract and can't be directly instantiated. Omitted if false. (since 2.10)
Name of parent type, if any (since 2.10)

1.1

qom-list-types (Command)

This command will return a list of types given search parameters

if specified, only return types that implement this type name
if true, include abstract types in the results

a list of ObjectTypeInfo or an empty list if no results are found

1.1

qom-list-properties (Command)

List properties associated with a QOM object.

the type name of an object

objects can create properties at runtime, for example to describe links between different devices and/or objects. These properties are not included in the output of this command.

a list of ObjectPropertyInfo describing object properties

2.12

CanHostSocketcanProperties (Object)

Properties for can-host-socketcan objects.

interface name of the host system CAN bus to connect to
object ID of the can-bus object to connect to the host interface

2.12

ColoCompareProperties (Object)

Properties for colo-compare objects.

name of the character device backend to use for the primary input (incoming packets are redirected to outdev)
name of the character device backend to use for secondary input (incoming packets are only compared to the input on primary_in and then dropped)
name of the character device backend to use for output
name of the iothread to run in
name of the character device backend to be used to communicate with the remote colo-frame (only for Xen COLO)
the maximum time to hold a packet from primary_in for comparison with an incoming packet on secondary_in in milliseconds (default: 3000)
the interval at which colo-compare checks whether packets from primary have timed out, in milliseconds (default: 3000)
the maximum number of packets to keep in the queue for comparing with incoming packets from secondary_in. If the queue is full and additional packets are received, the additional packets are dropped. (default: 1024)
if true, vnet header support is enabled (default: false)

2.8

CryptodevBackendProperties (Object)

Properties for cryptodev-backend and cryptodev-backend-builtin objects.

the number of queues for the cryptodev backend. Ignored for cryptodev-backend and must be 1 for cryptodev-backend-builtin. (default: 1)
limit total bytes per second (Since 8.0)
limit total operations per second (Since 8.0)

2.8

CryptodevVhostUserProperties (Object)

Properties for cryptodev-vhost-user objects.

the name of a Unix domain socket character device that connects to the vhost-user server

2.12

DBusVMStateProperties (Object)

Properties for dbus-vmstate objects.

the name of the DBus bus to connect to
a comma separated list of DBus IDs of helpers whose data should be included in the VM state on migration

5.0

NetfilterInsert (Enum)

Indicates where to insert a netfilter relative to a given other filter.

insert before the specified filter
insert behind the specified filter

5.0

NetfilterProperties (Object)

Properties for objects of classes derived from netfilter.

id of the network device backend to filter
indicates which queue(s) to filter (default: all)
indicates whether the filter is enabled ("on") or disabled ("off") (default: "on")
specifies where the filter should be inserted in the filter list. "head" means the filter is inserted at the head of the filter list, before any existing filters. "tail" means the filter is inserted at the tail of the filter list, behind any existing filters (default). "id=<id>" means the filter is inserted before or behind the filter specified by <id>, depending on the insert property. (default: "tail")
where to insert the filter relative to the filter given in position. Ignored if position is "head" or "tail". (default: behind)

2.5

FilterBufferProperties (Object)

Properties for filter-buffer objects.

a non-zero interval in microseconds. All packets arriving in the given interval are delayed until the end of the interval.

2.5

FilterDumpProperties (Object)

Properties for filter-dump objects.

the filename where the dumped packets should be stored
maximum number of bytes in a packet that are stored (default: 65536)

2.5

FilterMirrorProperties (Object)

Properties for filter-mirror objects.

the name of a character device backend to which all incoming packets are mirrored
if true, vnet header support is enabled (default: false)

2.6

FilterRedirectorProperties (Object)

Properties for filter-redirector objects.

At least one of indev or outdev must be present. If both are present, they must not refer to the same character device backend.

the name of a character device backend from which packets are received and redirected to the filtered network device
the name of a character device backend to which all incoming packets are redirected
if true, vnet header support is enabled (default: false)

2.6

FilterRewriterProperties (Object)

Properties for filter-rewriter objects.

if true, vnet header support is enabled (default: false)

2.8

InputBarrierProperties (Object)

Properties for input-barrier objects.

the screen name as declared in the screens section of barrier.conf
hostname of the Barrier server (default: "localhost")
TCP port of the Barrier server (default: "24800")
x coordinate of the leftmost pixel on the guest screen (default: "0")
y coordinate of the topmost pixel on the guest screen (default: "0")
the width of secondary screen in pixels (default: "1920")
the height of secondary screen in pixels (default: "1080")

4.2

InputLinuxProperties (Object)

Properties for input-linux objects.

the path of the host evdev device to use
if true, grab is toggled for all devices (e.g. both keyboard and mouse) instead of just one device (default: false)
enables auto-repeat events (default: false)
the key or key combination that toggles device grab (default: ctrl-ctrl)

2.6

EventLoopBaseProperties (Object)

Common properties for event loops

maximum number of requests in a batch for the AIO engine, 0 means that the engine will use its default. (default: 0)
minimum number of threads reserved in the thread pool (default:0)
maximum number of threads the thread pool can contain (default:64)

7.1

IothreadProperties (Object)

Properties for iothread objects.

the maximum number of nanoseconds to busy wait for events. 0 means polling is disabled (default: 32768 on POSIX hosts, 0 otherwise)
the multiplier used to increase the polling time when the algorithm detects it is missing events due to not polling long enough. 0 selects a default behaviour (default: 0)
the divisor used to decrease the polling time when the algorithm detects it is spending too long polling without encountering events. 0 selects a default behaviour (default: 0)

The aio-max-batch option is available since 6.1.

2.0

MainLoopProperties (Object)

Properties for the main-loop object.

7.1

MemoryBackendProperties (Object)

Properties for objects of classes derived from memory-backend.

if true, mark the memory as mergeable (default depends on the machine type)
if true, include the memory in core dumps (default depends on the machine type)
the list of NUMA host nodes to bind the memory to
the NUMA policy (default: 'default')
if true, preallocate memory (default: false)
number of CPU threads to use for prealloc (default: 1)
thread context to use for creation of preallocation threads (default: none) (since 7.2)
if false, the memory is private to QEMU; if true, it is shared (default: false)
if true, reserve swap space (or huge pages) if applicable (default: true) (since 6.1)
size of the memory region in bytes
if true, the canonical path is used for ramblock-id. Disable this for 4.0 machine types or older to allow migration with newer QEMU versions. (default: false generally, but true for machine types <= 4.0)

prealloc=true and reserve=false cannot be set at the same time. With reserve=true, the behavior depends on the operating system: for example, Linux will not reserve swap space for shared file mappings -- "not applicable". In contrast, reserve=false will bail out if it cannot be configured accordingly.

2.1

MemoryBackendFileProperties (Object)

Properties for memory-backend-file objects.

the base address alignment when QEMU mmap(2)s mem-path. Some backend stores specified by mem-path require an alignment different than the default one used by QEMU, e.g. the device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In such cases, users can specify the required alignment via this option. 0 selects a default alignment (currently the page size). (default: 0)
the offset into the target file that the region starts at. You can use this option to back multiple regions with a single file. Must be a multiple of the page size. (default: 0) (since 8.1)
if true, the file contents can be destroyed when QEMU exits, to avoid unnecessarily flushing data to the backing file. Note that discard-data is only an optimization, and QEMU might not discard file contents if it aborts unexpectedly or is terminated using SIGKILL. (default: false)
the path to either a shared memory or huge page filesystem mount
specifies whether the backing file specified by mem-path is in host persistent memory that can be accessed using the SNIA NVM programming model (e.g. Intel NVDIMM).
if true, the backing file is opened read-only; if false, it is opened read-write. (default: false)
whether to create Read Only Memory (ROM) that cannot be modified by the VM. Any write attempts to such ROM will be denied. Most use cases want writable RAM instead of ROM. However, selected use cases, like R/O NVDIMMs, can benefit from ROM. If set to 'on', create ROM; if set to 'off', create writable RAM; if set to 'auto', the value of the readonly property is used. This property is primarily helpful when we want to have proper RAM in configurations that would traditionally create ROM before this property was introduced: VM templating, where we want to open a file readonly (readonly set to true) and mark the memory to be private for QEMU (share set to false). For this use case, we need writable RAM instead of ROM, and want to set this property to 'off'. (default: auto, since 8.2)

2.1

MemoryBackendMemfdProperties (Object)

Properties for memory-backend-memfd objects.

The share boolean option is true by default with memfd.

if true, the file to be created resides in the hugetlbfs filesystem (default: false)
the hugetlb page size on systems that support multiple hugetlb page sizes (it must be a power of 2 value supported by the system). 0 selects a default page size. This option is ignored if hugetlb is false. (default: 0)
if true, create a sealed-file, which will block further resizing of the memory (default: true)

2.12

MemoryBackendEpcProperties (Object)

Properties for memory-backend-epc objects.

The share boolean option is true by default with epc

The merge boolean option is false by default with epc

The dump boolean option is false by default with epc

6.2

PrManagerHelperProperties (Object)

Properties for pr-manager-helper objects.

the path to a Unix domain socket for connecting to the external helper

2.11

QtestProperties (Object)

Properties for qtest objects.

the chardev to be used to receive qtest commands on.
the path to a log file

6.0

RemoteObjectProperties (Object)

Properties for x-remote-object objects.

file descriptor name previously passed via 'getfd' command
the id of the device to be associated with the file descriptor

6.0

VfioUserServerProperties (Object)

Properties for x-vfio-user-server objects.

socket to be used by the libvfio-user library
the ID of the device to be emulated at the server

7.1

RngProperties (Object)

Properties for objects of classes derived from rng.

if true, the device is opened immediately when applying this option and will probably fail when processing the next option. Don't use; only provided for compatibility. (default: false)

Member opened is deprecated. Setting true doesn't make sense, and false is already the default.

1.3

RngEgdProperties (Object)

Properties for rng-egd objects.

the name of a character device backend that provides the connection to the RNG daemon

1.3

RngRandomProperties (Object)

Properties for rng-random objects.

the filename of the device on the host to obtain entropy from (default: "/dev/urandom")

1.3

SevGuestProperties (Object)

Properties for sev-guest objects.

SEV device to use (default: "/dev/sev")
guest owners DH certificate (encoded with base64)
guest owners session parameters (encoded with base64)
SEV policy value (default: 0x1)
SEV firmware handle (default: 0)
C-bit location in page table entry (default: 0)
number of bits in physical addresses that become unavailable when SEV is enabled
if true, add hashes of kernel/initrd/cmdline to a designated guest firmware page for measured boot with -kernel (default: false) (since 6.2)

2.12

ThreadContextProperties (Object)

Properties for thread context objects.

the list of host CPU numbers used as CPU affinity for all threads created in the thread context (default: QEMU main thread CPU affinity)
the list of host node numbers that will be resolved to a list of host CPU numbers used as CPU affinity. This is a shortcut for specifying the list of host CPU numbers belonging to the host nodes manually by setting cpu-affinity. (default: QEMU main thread affinity)

7.2

ObjectType (Enum)

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Member x-remote-object is experimental.

6.0

ObjectOptions (Object)

Describes the options of a user creatable QOM object.

the class name for the object to be created
the name of the new object

6.0

object-add (Command)

Create a QOM object.

Nothing on success Error if qom-type is not a valid class name

2.0

-> { "execute": "object-add",
     "arguments": { "qom-type": "rng-random", "id": "rng1",
                    "filename": "/dev/hwrng" } }
<- { "return": {} }

object-del (Command)

Remove a QOM object.

the name of the QOM object to remove

Nothing on success Error if id is not a valid id for a QOM object

2.0

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

2024, The QEMU Project Developers

March 27, 2024 8.2.2