A number of changes I prefer to do in one shot: - Add a note about instability - Add multiple monitors example - Add 'Development Process' section - Small clarifications
Signed-off-by: Luiz Capitulino <lcapitul...@redhat.com> --- QMP/README | 67 +++++++++++++++++++++++++++++++++++++++++------------------ 1 files changed, 46 insertions(+), 21 deletions(-) diff --git a/QMP/README b/QMP/README index 35a80c7..8618c6f 100644 --- a/QMP/README +++ b/QMP/README @@ -5,44 +5,52 @@ Introduction ------------- The QEMU Monitor Protocol (QMP) allows applications to communicate with -QEMU's Monitor. +QEMU's Monitor the right way. -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: +However, QMP is still under heavy development and is considered an unstable +protocol. This means that its interface is going to have incompatible changes +between QEMU releases. We plan to make QMP stable as soon as possible. + +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 [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 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 -------------- @@ -59,8 +67,25 @@ Escape character is '^]'. { "execute": "query-version" } {"return": {"qemu": "0.12.50", "package": ""}} -Contact -------- +Development Process +------------------- + +When changing QMP's interface (by adding new commands, events or modifying +existing ones) it's mandatory to update the relevant documention, 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. It's very likely that the interface will change during review, updating + the code at the same time might be a big waste of time + +* The qmp-commands.txt file is generated from the qemu-monitor.hx one, which + is the file that should be edited. + +Homepage +-------- http://www.linux-kvm.org/page/MonitorProtocol -Luiz Fernando N. Capitulino <lcapitul...@redhat.com> -- 1.7.2.rc3.43.g24e7a