[libvirt] Making panic great again

[Daniel P. Berrange]

On Fri, Apr 28, 2017 at 11:28:47AM -0700, Ed Swierk wrote:
> On Fri, Apr 28, 2017 at 1:46 AM, Daniel P. Berrange <berrange at redhat.com> wrote:
> > With the watchdog we have a much wider set of actions that we can
> > instruct QEMU to do:
> >
> >     'reset' — default, forcefully reset the guest
> >     'shutdown' — gracefully shutdown the guest (not recommended)
> >     'poweroff' — forcefully power off the guest
> >     'pause' — pause the guest
> >     'none' — do nothing
> >     'dump' — automatically dump the guest Since 0.8.7
> >     'inject-nmi' — inject a non-maskable interrupt into the guest Since 1.2.17
> >
> > IMHO, we need an RFE against QEMU to allow pvpanic to have the same kind
> > of configurability as watchdog. So instead of QEMU blindly pausing the
> > guest, it can be told 'none' at which point libvirt can emit the event
> > and the admin can decide what further action they wish to take, if any.
> 
> I agree the panic device should support the same actions as the watchdog does.
> 
> All of them could be implemented without changing QEMU, though. For
> example libvirt could implement the 'none' action by resuming the
> guest. That means the guest still gets paused briefly, but I'd view
> fixing this as more of a performance optimization than a prerequisite
> for supporting the full set of actions.

I'd prefer to have explicit QEMU support, because it is less chance of
libvirt's hack/workaround being accidentally broken by future QEMU changes


Regards,
Daniel
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