@@ -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 <lcapitulino@redhat.com>
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 <lcapitulino@redhat.com> --- QMP/README | 67 +++++++++++++++++++++++++++++++++++++++++------------------ 1 files changed, 46 insertions(+), 21 deletions(-)