path: root/QMP
diff options
authorLuiz Capitulino <lcapitulino@redhat.com>2010-08-20 16:42:32 -0300
committerAnthony Liguori <aliguori@us.ibm.com>2010-08-22 17:11:06 -0500
commitd29f3196afddd356a8169780fa506f565adb5036 (patch)
tree823db8494af33232c61f409f4dbf4f2ef59f96aa /QMP
parent05705ce2f8dfd8dcb5622b66ece21c9737a8502c (diff)
QMP: Update README file
A number of changes I prefer to do in one shot: - Fix example - Small clarifications - Add multiple monitors example - Add 'Development Process' section Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'QMP')
1 files changed, 48 insertions, 23 deletions
diff --git a/QMP/README b/QMP/README
index 35a80c73e..948d4453d 100644
@@ -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
-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
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.
-Luiz Fernando N. Capitulino <lcapitulino@redhat.com>