Re: [Qemu-devel] Re: [patch 2/3] Add support for live block copy

[Anthony Liguori]

On 02/27/2011 10:02 AM, Dor Laor wrote:
> On 02/27/2011 03:49 PM, Anthony Liguori wrote:
> > On 02/27/2011 03:55 AM, Dor Laor wrote:
> > > What about a simpler approach were QMP events will be written to a
> > > event-log-file (or even named pipe).
> >
> > The management tool can just use a small daemon that does nothing other
> > than write QMP events to a log. There's no real need for this code to
> > live in QEMU.
>
> IIUC in case the management daemon will run qemu using named pipe for 
> qmp it will happen automatically.

No, the event model is changing (it was always intended to change 
though).  Events will need explicit registration so it's necessary to 
have bidirectional communication.

So you can't just do -qmp foo -chardev file:event.log,id=foo.  You won't 
actually see most of the events.

Regards,

Anthony Liguori

> If you agree to this approach it will simplify the more complex config 
> file option (although it is nice to have as independent option for 
> single hosts managed by simpler mgmts)
>
> > Since events are posted, even if we wrote it in QEMU, the event wouldn't
> > be guaranteed on disk by the time the event invocation returns.
> >
> > Regards,
> >
> > Anthony Liguori