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Diffstat (limited to 'QMP')
| -rw-r--r-- | QMP/README | 71 |
1 files changed, 48 insertions, 23 deletions
@@ -7,60 +7,85 @@ Introduction The QEMU Monitor Protocol (QMP) allows applications to communicate with QEMU's Monitor. -QMP is JSON[1] based and has the following features: +QMP is JSON[1] based and currently has the following features: - Lightweight, text-based, easy to parse data format -- Asynchronous events support -- Stability +- Asynchronous messages support (ie. events) +- Capabilities Negotiation -For more information, please, refer to the following files: +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 +o qmp-commands.txt QMP supported commands (auto-generated at build-time) o qmp-events.txt List of available asynchronous events There are also two simple Python scripts available: -o qmp-shell A shell -o vm-info Show some information about the Virtual Machine +o qmp-shell A shell +o vm-info Show some information about the Virtual Machine + +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, QEMU has to be started in "control mode". There are -two ways of doing this, the simplest one is using the the '-qmp' -command-line option. +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: -For example: + $ qemu [...] -qmp tcp:localhost:4444,server -$ 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. -Will start QEMU in control mode, waiting for a client TCP connection -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 -It is also possible to use the '-mon' command-line option to have -more complex combinations. Please, refer to the QEMU's manpage for -more information. +Please, refer to QEMU's manpage for more information. Simple Testing -------------- -To manually test QMP one can connect with telnet and issue commands: +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": "0.12.50", "package": ""}, "capabilities": []}} +{"QMP": {"version": {"qemu": {"micro": 50, "minor": 13, "major": 0}, "package": ""}, "capabilities": []}} { "execute": "qmp_capabilities" } {"return": {}} { "execute": "query-version" } -{"return": {"qemu": "0.12.50", "package": ""}} +{"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 qemu-monitor.hx one, which + is the file that should be edited. -Contact -------- +Homepage +-------- http://www.linux-kvm.org/page/MonitorProtocol -Luiz Fernando N. Capitulino <lcapitulino@redhat.com> |