On Tue, Jun 23, 2026 at 01:03:46PM +0200, Peter Krempa wrote:
> On Tue, Jun 23, 2026 at 10:55:16 +0100, Daniel P. Berrangé via Devel wrote:
> > Conceptually -object and object_add/object_del should be sufficient
> > for essentially all QEMU configuration....if only we ported all our
> > internal custom backends/devices/etc to QOM. That is of course a big
> > job which is why it hasn't happened.
> > 
> > This series started with the premise that the monitor is one of the
> > easier areas to convert since we have no more than three classes,
> > a common base, and QMP and HMP subclasses[1]. So why not give it a
> > go and thus unlock the ability to dynamically create/delete monitors
> > in QMP/HMP.
> > 
> > This series does the conversion in a great many small steps to better
> > understand the implications at each stage.
> > 
> > The high level outcome of this series is
> > 
> >  * HMP and QMP monitors are QOM objects, 'monitor-hmp' and
> >    'monitor-qmp' respectively
> > 
> >  * Both can be cold plugged and hot plugged. QMP only, can
> >    also be hot unplugged.
> > 
> >  * '-mon' is obsolete, deprecated and replaced by '-object',
> >    but -monitor, -qmp and kept  as high level syntax sugar
> 
> I was giving this a spin by implementing libvirt support for it. The
> basic usage seems to work well but I've encoutered a regression in
> behaviour which happens both when the QMP monitor is instantiated using
> the new syntax but also the old one
> ( -mon chardev=charmonitor,id=monitor,mode=control)
> 
> When libvirt wants to re-connect to a qemu running with these patches it
> re-issues a 'qmp_capabilities' command after connecting.
> 
> With these patches qemu does not respond to that command even when the
> old syntax is used. This makes libvirt stuck when re-connecting to VMs.

Oh that's odd, thanks for the warning. I'll investigate this.


With regards,
Daniel
-- 
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