[Qemu-devel] QMP event missed during startup

[Ross Lagerwall]

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?

Thanks,
--
Ross Lagerwall