Re: [Qemu-devel] QMP event missed during startup

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Ross Lagerwall (ross.lagerwall@citrix.com) wrote:
> Hi,
> 
> I have found an issue where QEMU emits the RESUME event during startup when
> it starts VM execution, but it is not possible to receive this event.
> 
> To repro this, run:
> qemu-system-i386 -m 256 -trace
> enable=monitor_protocol_event_emit,file=/tmp/out -qmp
> unix:/tmp/qmp,server,wait
> 
> QEMU will not start execution of the VM until something connects to the QMP
> socket (e.g. qmp-shell). Once connected, no event is received on the QMP
> connection but the tracepoint is hit indicating that an event has been
> emitted. I suspect that the event is emitted while the QMP client is doing
> the initial negotiation.
> 
> The reason I want to receive this event is that QEMU currently uses xenstore
> to communicate this information to the Xen toolstack (see
> xen-common.c:xen_change_state_handler) but we want to move to using QMP
> rather than xenstore for this kind of thing.
> 
> Is this a known issue or just a bug that should be fixed?

I'll leave it to Markus to say if it's a bug or not, but can't
you work around this by starting qemu with -S which leaves the guest
paused, and then continuing the guest when you have your QMP ?

Dave

> Thanks,
> -- 
> Ross Lagerwall
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK