qemu/QMP
Anthony Liguori 5ade767485 qom: quick and dirty QOM filesystem based on FUSE
Here's an example session:

anthony@titi:~/git/qemu/QMP$ QMP_SERVER=/tmp/server.sock ./qom-fuse tmp
anthony@titi:~/git/qemu/QMP$ ls tmp
machine  sysbus  type
anthony@titi:~/git/qemu/QMP$ ls tmp/machine
i440fx  peripheral  peripheral-anon  type  unattached
anthony@titi:~/git/qemu/QMP$ ls tmp/machine/i440fx
ioapic  parent_bus  pci.0  type
anthony@titi:~/git/qemu/QMP$ ls tmp/machine/i440fx/pci.0
child[0]  child[1]  child[2]  child[3]  child[4]  child[5]  type
anthony@titi:~/git/qemu/QMP$ ls tmp/machine/i440fx/pci.0/child[4]
addr                 legacy-addr                 multifunction  type
command_serr_enable  legacy-command_serr_enable  parent_bus
ide.0                legacy-multifunction        rombar
ide.1                legacy-romfile              romfile
anthony@titi:~/git/qemu/QMP$ cat tmp/machine/i440fx/pci.0/child[4]/type
piix3-ide
anthony@titi:~/git/qemu/QMP$ ls -al tmp/machine/i440fx/pci.0/child\[4\]/parent_bus
lrwxr-xr-x 2 anthony anthony 4096 1969-12-31 18:00 tmp/machine/i440fx/pci.0/child[4]/parent_bus -> ../../../machine/i440fx/pci.0

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-04-26 13:14:57 -05:00
..
qmp qmp: add test tool for QMP 2011-12-06 11:40:00 -02:00
qmp-events.txt qmp: add DEVICE_TRAY_MOVED event 2012-02-22 17:23:50 -02:00
qmp-shell QMP/qmp-shell: Introduce HMP mode 2010-11-17 09:52:24 -02:00
qmp-spec.txt qmp: document strict parsing 2012-03-27 09:15:52 -03:00
qmp.py qmp: make qmp.py easier to use 2012-02-22 12:18:26 -06:00
qom-fuse qom: quick and dirty QOM filesystem based on FUSE 2012-04-26 13:14:57 -05:00
qom-get qom: add test tools 2012-02-22 12:18:26 -06:00
qom-list qom: add test tools 2012-02-22 12:18:26 -06:00
qom-set qom: add test tools 2012-02-22 12:18:26 -06:00
README QMP: Drop vm-info example script 2010-11-17 09:51:07 -02:00

                          QEMU Monitor Protocol
                          =====================

Introduction
-------------

The QEMU Monitor Protocol (QMP) allows applications to communicate with
QEMU's Monitor.

QMP is JSON[1] based and currently has the following features:

- 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 Monitor Protocol current specification
o qmp-commands.txt  QMP supported commands (auto-generated at build-time)
o qmp-events.txt    List of available asynchronous events

There is also a simple Python script called 'qmp-shell' available.

IMPORTANT: It's strongly recommended to read the 'Stability Considerations'
section in the qmp-commands.txt file before making any serious use of QMP.


[1] http://www.json.org

Usage
-----

To enable QMP, you need a QEMU monitor instance in "control mode". There are
two ways of doing this.

The simplest one is using the '-qmp' command-line option. The following
example makes QMP available on localhost port 4444:

  $ qemu [...] -qmp tcp:localhost:4444,server

However, in order to have more complex combinations, like multiple monitors,
the '-mon' command-line option should be used along with the '-chardev' one.
For instance, the following example creates one user monitor on stdio and one
QMP monitor on localhost port 4444.

   $ qemu [...] -chardev stdio,id=mon0 -mon chardev=mon0,mode=readline \
                -chardev socket,id=mon1,host=localhost,port=4444,server \
                -mon chardev=mon1,mode=control

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": 13, "major": 0}, "package": ""}, "capabilities": []}}
{ "execute": "qmp_capabilities" }
{"return": {}}
{ "execute": "query-version" }
{"return": {"qemu": {"micro": 50, "minor": 13, "major": 0}, "package": ""}}

Development Process
-------------------

When changing QMP's interface (by adding new commands, events or modifying
existing ones) it's mandatory to update the relevant documentation, which is
one (or more) of the files listed in the 'Introduction' section*.

Also, it's strongly recommended to send the documentation patch first, before
doing any code change. This is so because:

  1. Avoids the code dictating the interface

  2. Review can improve your interface.  Letting that happen before
     you implement it can save you work.

* The qmp-commands.txt file is generated from the qmp-commands.hx one, which
  is the file that should be edited.

Homepage
--------

http://wiki.qemu.org/QMP