[libvirt] Transitioning from HMP to QMP for QEMU

Stefan Berger stefanb at linux.vnet.ibm.com
Thu Dec 15 13:31:39 UTC 2011

On 12/15/2011 08:02 AM, Stefan Hajnoczi wrote:
> What is the status of QEMU's transition from HMP to the QMP interface?
> My current understanding is that QEMU provides new HMP commands for
> humans, but HMP is being phased out as an API.  Management tools
> should rely only on QMP for new commands.  That would mean new HMP
> commands are not guaranteed to produce backwards-compatible output
> because tools are not supposed to parse the output.
> On the libvirt side, new QEMU features should only be supported via
> the json monitor in the future (i.e. human monitor patches should not
> be sent/merged)?  Existing HMP commands will still need the human
> monitor support in order to handle old QEMU versions gracefully, but
> I'm thinking about new commands only.
> Does everyone agree on this?  I think this is an important discussion
> if we want our management interface to get better and more consistent
> in the future.
HMP is good for a human to interaction with Qemu, QMP mostly for a 
machine. At least that's my impression. If there are no new HMP commands 
hopefully there is an alternative for human interaction.


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