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Diffstat (limited to 'qemu/docs/qmp')
| -rw-r--r-- | qemu/docs/qmp/README | 87 | ||||
| -rw-r--r-- | qemu/docs/qmp/qmp-events.txt | 664 | ||||
| -rw-r--r-- | qemu/docs/qmp/qmp-spec.txt | 336 |
3 files changed, 0 insertions, 1087 deletions
diff --git a/qemu/docs/qmp/README b/qemu/docs/qmp/README deleted file mode 100644 index f6a3a031e..000000000 --- a/qemu/docs/qmp/README +++ /dev/null @@ -1,87 +0,0 @@ - QEMU Machine Protocol - ===================== - -Introduction ------------- - -The QEMU Machine Protocol (QMP) allows applications to operate a -QEMU instance. - -QMP is JSON[1] based and features the following: - -- Lightweight, text-based, easy to parse data format -- Asynchronous messages support (ie. events) -- Capabilities Negotiation - -For detailed information on QMP's usage, please, refer to the following files: - -o qmp-spec.txt QEMU Machine Protocol current specification -o qmp-commands.txt QMP supported commands (auto-generated at build-time) -o qmp-events.txt List of available asynchronous events - -[1] http://www.json.org - -Usage ------ - -You can use the -qmp option to enable QMP. For example, the following -makes QMP available on localhost port 4444: - -$ qemu [...] -qmp tcp:localhost:4444,server,nowait - -However, for more flexibility and to make use of more options, the -mon -command-line option should be used. For instance, the following example -creates one HMP instance (human monitor) on stdio and one QMP instance -on localhost port 4444: - -$ qemu [...] -chardev stdio,id=mon0 -mon chardev=mon0,mode=readline \ - -chardev socket,id=mon1,host=localhost,port=4444,server,nowait \ - -mon chardev=mon1,mode=control,pretty=on - -Please, refer to QEMU's manpage for more information. - -Simple Testing --------------- - -To manually test QMP one can connect with telnet and issue commands by hand: - -$ telnet localhost 4444 -Trying 127.0.0.1... -Connected to localhost. -Escape character is '^]'. -{ - "QMP": { - "version": { - "qemu": { - "micro": 50, - "minor": 6, - "major": 1 - }, - "package": "" - }, - "capabilities": [ - ] - } -} - -{ "execute": "qmp_capabilities" } -{ - "return": { - } -} - -{ "execute": "query-status" } -{ - "return": { - "status": "prelaunch", - "singlestep": false, - "running": false - } -} - -Please, refer to the qapi-schema.json file for a complete command reference. - -QMP wiki page -------------- - -http://wiki.qemu-project.org/QMP diff --git a/qemu/docs/qmp/qmp-events.txt b/qemu/docs/qmp/qmp-events.txt deleted file mode 100644 index d92cc4833..000000000 --- a/qemu/docs/qmp/qmp-events.txt +++ /dev/null @@ -1,664 +0,0 @@ - QEMU Machine Protocol Events - ============================ - -ACPI_DEVICE_OST ---------------- - -Emitted when guest executes ACPI _OST method. - - - data: ACPIOSTInfo type as described in qapi-schema.json - -{ "event": "ACPI_DEVICE_OST", - "data": { "device": "d1", "slot": "0", "slot-type": "DIMM", "source": 1, "status": 0 } } - -BALLOON_CHANGE --------------- - -Emitted when the guest changes the actual BALLOON level. This -value is equivalent to the 'actual' field return by the -'query-balloon' command - -Data: - -- "actual": actual level of the guest memory balloon in bytes (json-number) - -Example: - -{ "event": "BALLOON_CHANGE", - "data": { "actual": 944766976 }, - "timestamp": { "seconds": 1267020223, "microseconds": 435656 } } - -BLOCK_IMAGE_CORRUPTED ---------------------- - -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. - -Data: - -- "device": Device name (json-string) -- "node-name": Node name (json-string, optional) -- "msg": Informative message (e.g., reason for the corruption) - (json-string) -- "offset": If the corruption resulted from an image access, this - is the host's access offset into the image - (json-int, optional) -- "size": If the corruption resulted from an image access, this - is the access size (json-int, optional) - -Example: - -{ "event": "BLOCK_IMAGE_CORRUPTED", - "data": { "device": "ide0-hd0", "node-name": "node0", - "msg": "Prevented active L1 table overwrite", "offset": 196608, - "size": 65536 }, - "timestamp": { "seconds": 1378126126, "microseconds": 966463 } } - -BLOCK_IO_ERROR --------------- - -Emitted when a disk I/O error occurs. - -Data: - -- "device": device name (json-string) -- "operation": I/O operation (json-string, "read" or "write") -- "action": action that has been taken, it's one of the following (json-string): - "ignore": error has been ignored - "report": error has been reported to the device - "stop": the VM is going to stop because of the error - -Example: - -{ "event": "BLOCK_IO_ERROR", - "data": { "device": "ide0-hd1", - "operation": "write", - "action": "stop" }, - "timestamp": { "seconds": 1265044230, "microseconds": 450486 } } - -Note: If action is "stop", a STOP event will eventually follow the -BLOCK_IO_ERROR event. - -BLOCK_JOB_CANCELLED -------------------- - -Emitted when a block job has been cancelled. - -Data: - -- "type": Job type (json-string; "stream" for image streaming - "commit" for block commit) -- "device": Device name (json-string) -- "len": Maximum progress value (json-int) -- "offset": Current progress value (json-int) - On success this is equal to len. - On failure this is less than len. -- "speed": Rate limit, bytes per second (json-int) - -Example: - -{ "event": "BLOCK_JOB_CANCELLED", - "data": { "type": "stream", "device": "virtio-disk0", - "len": 10737418240, "offset": 134217728, - "speed": 0 }, - "timestamp": { "seconds": 1267061043, "microseconds": 959568 } } - -BLOCK_JOB_COMPLETED -------------------- - -Emitted when a block job has completed. - -Data: - -- "type": Job type (json-string; "stream" for image streaming - "commit" for block commit) -- "device": Device name (json-string) -- "len": Maximum progress value (json-int) -- "offset": Current progress value (json-int) - On success this is equal to len. - On failure this is less than len. -- "speed": Rate limit, bytes per second (json-int) -- "error": Error message (json-string, optional) - 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. - -Example: - -{ "event": "BLOCK_JOB_COMPLETED", - "data": { "type": "stream", "device": "virtio-disk0", - "len": 10737418240, "offset": 10737418240, - "speed": 0 }, - "timestamp": { "seconds": 1267061043, "microseconds": 959568 } } - -BLOCK_JOB_ERROR ---------------- - -Emitted when a block job encounters an error. - -Data: - -- "device": device name (json-string) -- "operation": I/O operation (json-string, "read" or "write") -- "action": action that has been taken, it's one of the following (json-string): - "ignore": error has been ignored, the job may fail later - "report": error will be reported and the job canceled - "stop": error caused job to be paused - -Example: - -{ "event": "BLOCK_JOB_ERROR", - "data": { "device": "ide0-hd1", - "operation": "write", - "action": "stop" }, - "timestamp": { "seconds": 1265044230, "microseconds": 450486 } } - -BLOCK_JOB_READY ---------------- - -Emitted when a block job is ready to complete. - -Data: - -- "type": Job type (json-string; "stream" for image streaming - "commit" for block commit) -- "device": Device name (json-string) -- "len": Maximum progress value (json-int) -- "offset": Current progress value (json-int) - On success this is equal to len. - On failure this is less than len. -- "speed": Rate limit, bytes per second (json-int) - -Example: - -{ "event": "BLOCK_JOB_READY", - "data": { "device": "drive0", "type": "mirror", "speed": 0, - "len": 2097152, "offset": 2097152 } - "timestamp": { "seconds": 1265044230, "microseconds": 450486 } } - -Note: The "ready to complete" status is always reset by a BLOCK_JOB_ERROR -event. - -DEVICE_DELETED --------------- - -Emitted whenever the device removal completion is acknowledged -by the guest. -At this point, it's safe to reuse the specified device ID. -Device removal can be initiated by the guest or by HMP/QMP commands. - -Data: - -- "device": device name (json-string, optional) -- "path": device path (json-string) - -{ "event": "DEVICE_DELETED", - "data": { "device": "virtio-net-pci-0", - "path": "/machine/peripheral/virtio-net-pci-0" }, - "timestamp": { "seconds": 1265044230, "microseconds": 450486 } } - -DEVICE_TRAY_MOVED ------------------ - -It's emitted whenever the tray of a removable device is moved by the guest -or by HMP/QMP commands. - -Data: - -- "device": device name (json-string) -- "tray-open": true if the tray has been opened or false if it has been closed - (json-bool) - -{ "event": "DEVICE_TRAY_MOVED", - "data": { "device": "ide1-cd0", - "tray-open": true - }, - "timestamp": { "seconds": 1265044230, "microseconds": 450486 } } - -GUEST_PANICKED --------------- - -Emitted when guest OS panic is detected. - -Data: - -- "action": Action that has been taken (json-string, currently always "pause"). - -Example: - -{ "event": "GUEST_PANICKED", - "data": { "action": "pause" } } - -MEM_UNPLUG_ERROR --------------------- -Emitted when memory hot unplug error occurs. - -Data: - -- "device": device name (json-string) -- "msg": Informative message (e.g., reason for the error) (json-string) - -Example: - -{ "event": "MEM_UNPLUG_ERROR" - "data": { "device": "dimm1", - "msg": "acpi: device unplug for unsupported device" - }, - "timestamp": { "seconds": 1265044230, "microseconds": 450486 } } - -NIC_RX_FILTER_CHANGED ---------------------- - -The event is emitted once until the query command is executed, -the first event will always be emitted. - -Data: - -- "name": net client name (json-string) -- "path": device path (json-string) - -{ "event": "NIC_RX_FILTER_CHANGED", - "data": { "name": "vnet0", - "path": "/machine/peripheral/vnet0/virtio-backend" }, - "timestamp": { "seconds": 1368697518, "microseconds": 326866 } } -} - -POWERDOWN ---------- - -Emitted when the Virtual Machine is powered down through the power -control system, such as via ACPI. - -Data: None. - -Example: - -{ "event": "POWERDOWN", - "timestamp": { "seconds": 1267040730, "microseconds": 682951 } } - -QUORUM_FAILURE --------------- - -Emitted by the Quorum block driver if it fails to establish a quorum. - -Data: - -- "reference": device name if defined else node name. -- "sector-num": Number of the first sector of the failed read operation. -- "sectors-count": Failed read operation sector count. - -Example: - -{ "event": "QUORUM_FAILURE", - "data": { "reference": "usr1", "sector-num": 345435, "sectors-count": 5 }, - "timestamp": { "seconds": 1344522075, "microseconds": 745528 } } - -QUORUM_REPORT_BAD ------------------ - -Emitted to report a corruption of a Quorum file. - -Data: - -- "error": Error message (json-string, optional) - 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. -- "node-name": The graph node name of the block driver state. -- "sector-num": Number of the first sector of the failed read operation. -- "sectors-count": Failed read operation sector count. - -Example: - -{ "event": "QUORUM_REPORT_BAD", - "data": { "node-name": "1.raw", "sector-num": 345435, "sectors-count": 5 }, - "timestamp": { "seconds": 1344522075, "microseconds": 745528 } } - -RESET ------ - -Emitted when the Virtual Machine is reset. - -Data: None. - -Example: - -{ "event": "RESET", - "timestamp": { "seconds": 1267041653, "microseconds": 9518 } } - -RESUME ------- - -Emitted when the Virtual Machine resumes execution. - -Data: None. - -Example: - -{ "event": "RESUME", - "timestamp": { "seconds": 1271770767, "microseconds": 582542 } } - -RTC_CHANGE ----------- - -Emitted when the guest changes the RTC time. - -Data: - -- "offset": Offset between base RTC clock (as specified by -rtc base), and -new RTC clock value (json-number) - -Example: - -{ "event": "RTC_CHANGE", - "data": { "offset": 78 }, - "timestamp": { "seconds": 1267020223, "microseconds": 435656 } } - -SHUTDOWN --------- - -Emitted when the Virtual Machine has shut down, indicating that qemu -is about to exit. - -Data: None. - -Example: - -{ "event": "SHUTDOWN", - "timestamp": { "seconds": 1267040730, "microseconds": 682951 } } - -Note: If the command-line option "-no-shutdown" has been specified, a STOP -event will eventually follow the SHUTDOWN event. - -SPICE_CONNECTED ---------------- - -Emitted when a SPICE client connects. - -Data: - -- "server": Server information (json-object) - - "host": IP address (json-string) - - "port": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") -- "client": Client information (json-object) - - "host": IP address (json-string) - - "port": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - -Example: - -{ "timestamp": {"seconds": 1290688046, "microseconds": 388707}, - "event": "SPICE_CONNECTED", - "data": { - "server": { "port": "5920", "family": "ipv4", "host": "127.0.0.1"}, - "client": {"port": "52873", "family": "ipv4", "host": "127.0.0.1"} -}} - -SPICE_DISCONNECTED ------------------- - -Emitted when a SPICE client disconnects. - -Data: - -- "server": Server information (json-object) - - "host": IP address (json-string) - - "port": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") -- "client": Client information (json-object) - - "host": IP address (json-string) - - "port": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - -Example: - -{ "timestamp": {"seconds": 1290688046, "microseconds": 388707}, - "event": "SPICE_DISCONNECTED", - "data": { - "server": { "port": "5920", "family": "ipv4", "host": "127.0.0.1"}, - "client": {"port": "52873", "family": "ipv4", "host": "127.0.0.1"} -}} - -SPICE_INITIALIZED ------------------ - -Emitted after initial handshake and authentication takes place (if any) -and the SPICE channel is up and running - -Data: - -- "server": Server information (json-object) - - "host": IP address (json-string) - - "port": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - - "auth": authentication method (json-string, optional) -- "client": Client information (json-object) - - "host": IP address (json-string) - - "port": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - - "connection-id": spice connection id. All channels with the same id - belong to the same spice session (json-int) - - "channel-type": channel type. "1" is the main control channel, filter for - this one if you want track spice sessions only (json-int) - - "channel-id": channel id. Usually "0", might be different needed when - multiple channels of the same type exist, such as multiple - display channels in a multihead setup (json-int) - - "tls": whevener the channel is encrypted (json-bool) - -Example: - -{ "timestamp": {"seconds": 1290688046, "microseconds": 417172}, - "event": "SPICE_INITIALIZED", - "data": {"server": {"auth": "spice", "port": "5921", - "family": "ipv4", "host": "127.0.0.1"}, - "client": {"port": "49004", "family": "ipv4", "channel-type": 3, - "connection-id": 1804289383, "host": "127.0.0.1", - "channel-id": 0, "tls": true} -}} - -SPICE_MIGRATE_COMPLETED ------------------------ - -Emitted when SPICE migration has completed - -Data: None. - -Example: - -{ "timestamp": {"seconds": 1290688046, "microseconds": 417172}, - "event": "SPICE_MIGRATE_COMPLETED" } - -MIGRATION ---------- - -Emitted when a migration event happens - -Data: None. - - - "status": migration status - See MigrationStatus in ~/qapi-schema.json for possible values - -Example: - -{"timestamp": {"seconds": 1432121972, "microseconds": 744001}, - "event": "MIGRATION", "data": {"status": "completed"}} - -STOP ----- - -Emitted when the Virtual Machine is stopped. - -Data: None. - -Example: - -{ "event": "STOP", - "timestamp": { "seconds": 1267041730, "microseconds": 281295 } } - -SUSPEND -------- - -Emitted when guest enters S3 state. - -Data: None. - -Example: - -{ "event": "SUSPEND", - "timestamp": { "seconds": 1344456160, "microseconds": 309119 } } - -SUSPEND_DISK ------------- - -Emitted when the guest makes a request to enter S4 state. - -Data: None. - -Example: - -{ "event": "SUSPEND_DISK", - "timestamp": { "seconds": 1344456160, "microseconds": 309119 } } - -Note: QEMU shuts down when entering S4 state. - -VNC_CONNECTED -------------- - -Emitted when a VNC client establishes a connection. - -Data: - -- "server": Server information (json-object) - - "host": IP address (json-string) - - "service": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - - "auth": authentication method (json-string, optional) -- "client": Client information (json-object) - - "host": IP address (json-string) - - "service": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - -Example: - -{ "event": "VNC_CONNECTED", - "data": { - "server": { "auth": "sasl", "family": "ipv4", - "service": "5901", "host": "0.0.0.0" }, - "client": { "family": "ipv4", "service": "58425", - "host": "127.0.0.1" } }, - "timestamp": { "seconds": 1262976601, "microseconds": 975795 } } - - -Note: This event is emitted before any authentication takes place, thus -the authentication ID is not provided. - -VNC_DISCONNECTED ----------------- - -Emitted when the connection is closed. - -Data: - -- "server": Server information (json-object) - - "host": IP address (json-string) - - "service": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - - "auth": authentication method (json-string, optional) -- "client": Client information (json-object) - - "host": IP address (json-string) - - "service": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - - "x509_dname": TLS dname (json-string, optional) - - "sasl_username": SASL username (json-string, optional) - -Example: - -{ "event": "VNC_DISCONNECTED", - "data": { - "server": { "auth": "sasl", "family": "ipv4", - "service": "5901", "host": "0.0.0.0" }, - "client": { "family": "ipv4", "service": "58425", - "host": "127.0.0.1", "sasl_username": "luiz" } }, - "timestamp": { "seconds": 1262976601, "microseconds": 975795 } } - -VNC_INITIALIZED ---------------- - -Emitted after authentication takes place (if any) and the VNC session is -made active. - -Data: - -- "server": Server information (json-object) - - "host": IP address (json-string) - - "service": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - - "auth": authentication method (json-string, optional) -- "client": Client information (json-object) - - "host": IP address (json-string) - - "service": port number (json-string) - - "family": address family (json-string, "ipv4" or "ipv6") - - "x509_dname": TLS dname (json-string, optional) - - "sasl_username": SASL username (json-string, optional) - -Example: - -{ "event": "VNC_INITIALIZED", - "data": { - "server": { "auth": "sasl", "family": "ipv4", - "service": "5901", "host": "0.0.0.0"}, - "client": { "family": "ipv4", "service": "46089", - "host": "127.0.0.1", "sasl_username": "luiz" } }, - "timestamp": { "seconds": 1263475302, "microseconds": 150772 } } - -VSERPORT_CHANGE ---------------- - -Emitted when the guest opens or closes a virtio-serial port. - -Data: - -- "id": device identifier of the virtio-serial port (json-string) -- "open": true if the guest has opened the virtio-serial port (json-bool) - -Example: - -{ "event": "VSERPORT_CHANGE", - "data": { "id": "channel0", "open": true }, - "timestamp": { "seconds": 1401385907, "microseconds": 422329 } } - -WAKEUP ------- - -Emitted when the guest has woken up from S3 and is running. - -Data: None. - -Example: - -{ "event": "WAKEUP", - "timestamp": { "seconds": 1344522075, "microseconds": 745528 } } - -WATCHDOG --------- - -Emitted when the watchdog device's timer is expired. - -Data: - -- "action": Action that has been taken, it's one of the following (json-string): - "reset", "shutdown", "poweroff", "pause", "debug", or "none" - -Example: - -{ "event": "WATCHDOG", - "data": { "action": "reset" }, - "timestamp": { "seconds": 1267061043, "microseconds": 959568 } } - -Note: If action is "reset", "shutdown", or "pause" the WATCHDOG event is -followed respectively by the RESET, SHUTDOWN, or STOP events. diff --git a/qemu/docs/qmp/qmp-spec.txt b/qemu/docs/qmp/qmp-spec.txt deleted file mode 100644 index 4c28cd943..000000000 --- a/qemu/docs/qmp/qmp-spec.txt +++ /dev/null @@ -1,336 +0,0 @@ - QEMU Machine Protocol Specification - -0. About This Document -====================== - -Copyright (C) 2009-2015 Red Hat, Inc. - -This work is licensed under the terms of the GNU GPL, version 2 or -later. See the COPYING file in the top-level directory. - -1. Introduction -=============== - -This document specifies the QEMU Machine Protocol (QMP), a JSON-based -protocol which is available for applications to operate QEMU at the -machine-level. It is also in use by the QEMU Guest Agent (QGA), which -is available for host applications to interact with the guest -operating system. - -2. Protocol Specification -========================= - -This section details the protocol format. For the purpose of this document -"Client" is any application which is using QMP to communicate with QEMU and -"Server" is QEMU itself. - -JSON data structures, when mentioned in this document, are always in the -following format: - - json-DATA-STRUCTURE-NAME - -Where DATA-STRUCTURE-NAME is any valid JSON data structure, as defined -by the JSON standard: - -http://www.ietf.org/rfc/rfc7159.txt - -The protocol is always encoded in UTF-8 except for synchronization -bytes (documented below); although thanks to json-string escape -sequences, the server will reply using only the strict ASCII subset. - -For convenience, json-object members mentioned in this document will -be in a certain order. However, in real protocol usage they can be in -ANY order, thus no particular order should be assumed. On the other -hand, use of json-array elements presumes that preserving order is -important unless specifically documented otherwise. Repeating a key -within a json-object gives unpredictable results. - -Also for convenience, the server will accept an extension of -'single-quoted' strings in place of the usual "double-quoted" -json-string, and both input forms of strings understand an additional -escape sequence of "\'" for a single quote. The server will only use -double quoting on output. - -2.1 General Definitions ------------------------ - -2.1.1 All interactions transmitted by the Server are json-objects, always - terminating with CRLF - -2.1.2 All json-objects members are mandatory when not specified otherwise - -2.2 Server Greeting -------------------- - -Right when connected the Server will issue a greeting message, which signals -that the connection has been successfully established and that the Server is -ready for capabilities negotiation (for more information refer to section -'4. Capabilities Negotiation'). - -The greeting message format is: - -{ "QMP": { "version": json-object, "capabilities": json-array } } - - Where, - -- The "version" member contains the Server's version information (the format - is the same of the query-version command) -- The "capabilities" member specify the availability of features beyond the - baseline specification; the order of elements in this array has no - particular significance, so a client must search the entire array - when looking for a particular capability - -2.2.1 Capabilities ------------------- - -As of the date this document was last revised, no server or client -capability strings have been defined. - - -2.3 Issuing Commands --------------------- - -The format for command execution is: - -{ "execute": json-string, "arguments": json-object, "id": json-value } - - Where, - -- The "execute" member identifies the command to be executed by the Server -- The "arguments" member is used to pass any arguments required for the - execution of the command, it is optional when no arguments are - required. Each command documents what contents will be considered - valid when handling the json-argument -- The "id" member is a transaction identification associated with the - command execution, it is optional and will be part of the response if - provided. The "id" member can be any json-value, although most - clients merely use a json-number incremented for each successive - command - -2.4 Commands Responses ----------------------- - -There are two possible responses which the Server will issue as the result -of a command execution: success or error. - -2.4.1 success -------------- - -The format of a success response is: - -{ "return": json-value, "id": json-value } - - Where, - -- The "return" member contains the data returned by the command, which - is defined on a per-command basis (usually a json-object or - json-array of json-objects, but sometimes a json-number, json-string, - or json-array of json-strings); it is an empty json-object if the - command does not return data -- The "id" member contains the transaction identification associated - with the command execution if issued by the Client - -2.4.2 error ------------ - -The format of an error response is: - -{ "error": { "class": json-string, "desc": json-string }, "id": json-value } - - Where, - -- The "class" member contains the error class name (eg. "GenericError") -- The "desc" member is a human-readable error message. Clients should - not attempt to parse this message. -- The "id" member contains the transaction identification associated with - the command execution if issued by the Client - -NOTE: Some errors can occur before the Server is able to read the "id" member, -in these cases the "id" member will not be part of the error response, even -if provided by the client. - -2.5 Asynchronous events ------------------------ - -As a result of state changes, the Server may send messages unilaterally -to the Client at any time, when not in the middle of any other -response. They are called "asynchronous events". - -The format of asynchronous events is: - -{ "event": json-string, "data": json-object, - "timestamp": { "seconds": json-number, "microseconds": json-number } } - - Where, - -- The "event" member contains the event's name -- The "data" member contains event specific data, which is defined in a - per-event basis, it is optional -- The "timestamp" member contains the exact time of when the event - occurred in the Server. It is a fixed json-object with time in - seconds and microseconds relative to the Unix Epoch (1 Jan 1970); if - there is a failure to retrieve host time, both members of the - timestamp will be set to -1. - -For a listing of supported asynchronous events, please, refer to the -qmp-events.txt file. - -2.5 QGA Synchronization ------------------------ - -When using QGA, an additional synchronization feature is built into -the protocol. If the Client sends a raw 0xFF sentinel byte (not valid -JSON), then the Server will reset its state and discard all pending -data prior to the sentinel. Conversely, if the Client makes use of -the 'guest-sync-delimited' command, the Server will send a raw 0xFF -sentinel byte prior to its response, to aid the Client in discarding -any data prior to the sentinel. - - -3. QMP Examples -=============== - -This section provides some examples of real QMP usage, in all of them -"C" stands for "Client" and "S" stands for "Server". - -3.1 Server greeting -------------------- - -S: { "QMP": { "version": { "qemu": { "micro": 50, "minor": 6, "major": 1 }, - "package": ""}, "capabilities": []}} - -3.2 Client QMP negotiation --------------------------- -C: { "execute": "qmp_capabilities" } -S: { "return": {}} - -3.3 Simple 'stop' execution ---------------------------- - -C: { "execute": "stop" } -S: { "return": {} } - -3.4 KVM information -------------------- - -C: { "execute": "query-kvm", "id": "example" } -S: { "return": { "enabled": true, "present": true }, "id": "example"} - -3.5 Parsing error ------------------- - -C: { "execute": } -S: { "error": { "class": "GenericError", "desc": "Invalid JSON syntax" } } - -3.6 Powerdown event -------------------- - -S: { "timestamp": { "seconds": 1258551470, "microseconds": 802384 }, - "event": "POWERDOWN" } - -4. Capabilities Negotiation -=========================== - -When a Client successfully establishes a connection, the Server is in -Capabilities Negotiation mode. - -In this mode only the qmp_capabilities command is allowed to run, all -other commands will return the CommandNotFound error. Asynchronous -messages are not delivered either. - -Clients should use the qmp_capabilities command to enable capabilities -advertised in the Server's greeting (section '2.2 Server Greeting') they -support. - -When the qmp_capabilities command is issued, and if it does not return an -error, the Server enters in Command mode where capabilities changes take -effect, all commands (except qmp_capabilities) are allowed and asynchronous -messages are delivered. - -5 Compatibility Considerations -============================== - -All protocol changes or new features which modify the protocol format in an -incompatible way are disabled by default and will be advertised by the -capabilities array (section '2.2 Server Greeting'). Thus, Clients can check -that array and enable the capabilities they support. - -The QMP Server performs a type check on the arguments to a command. It -generates an error if a value does not have the expected type for its -key, or if it does not understand a key that the Client included. The -strictness of the Server catches wrong assumptions of Clients about -the Server's schema. Clients can assume that, when such validation -errors occur, they will be reported before the command generated any -side effect. - -However, Clients must not assume any particular: - -- Length of json-arrays -- Size of json-objects; in particular, future versions of QEMU may add - new keys and Clients should be able to ignore them. -- Order of json-object members or json-array elements -- Amount of errors generated by a command, that is, new errors can be added - to any existing command in newer versions of the Server - -Any command or field name beginning with "x-" is deemed experimental, -and may be withdrawn or changed in an incompatible manner in a future -release. - -Of course, the Server does guarantee to send valid JSON. But apart from -this, a Client should be "conservative in what they send, and liberal in -what they accept". - -6. Downstream extension of QMP -============================== - -We recommend that downstream consumers of QEMU do *not* modify QMP. -Management tools should be able to support both upstream and downstream -versions of QMP without special logic, and downstream extensions are -inherently at odds with that. - -However, we recognize that it is sometimes impossible for downstreams to -avoid modifying QMP. Both upstream and downstream need to take care to -preserve long-term compatibility and interoperability. - -To help with that, QMP reserves JSON object member names beginning with -'__' (double underscore) for downstream use ("downstream names"). This -means upstream will never use any downstream names for its commands, -arguments, errors, asynchronous events, and so forth. - -Any new names downstream wishes to add must begin with '__'. To -ensure compatibility with other downstreams, it is strongly -recommended that you prefix your downstream names with '__RFQDN_' where -RFQDN is a valid, reverse fully qualified domain name which you -control. For example, a qemu-kvm specific monitor command would be: - - (qemu) __org.linux-kvm_enable_irqchip - -Downstream must not change the server greeting (section 2.2) other than -to offer additional capabilities. But see below for why even that is -discouraged. - -Section '5 Compatibility Considerations' applies to downstream as well -as to upstream, obviously. It follows that downstream must behave -exactly like upstream for any input not containing members with -downstream names ("downstream members"), except it may add members -with downstream names to its output. - -Thus, a client should not be able to distinguish downstream from -upstream as long as it doesn't send input with downstream members, and -properly ignores any downstream members in the output it receives. - -Advice on downstream modifications: - -1. Introducing new commands is okay. If you want to extend an existing - command, consider introducing a new one with the new behaviour - instead. - -2. Introducing new asynchronous messages is okay. If you want to extend - an existing message, consider adding a new one instead. - -3. Introducing new errors for use in new commands is okay. Adding new - errors to existing commands counts as extension, so 1. applies. - -4. New capabilities are strongly discouraged. Capabilities are for - evolving the basic protocol, and multiple diverging basic protocol - dialects are most undesirable. |