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Re: [Qemu-devel] QMP event missed during startup
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] QMP event missed during startup |
Date: |
Mon, 30 Oct 2017 17:18:15 +0000 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
* Ross Lagerwall (address@hidden) 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 / address@hidden / Manchester, UK