Re: [Qemu-devel] [RFC PATCH v2 0/3] Start fixing the pvpanic mess

[Daniel P. Berrange]

On Wed, Aug 21, 2013 at 06:51:11PM +0200, Paolo Bonzini wrote:
> Il 21/08/2013 18:48, Daniel P. Berrange ha scritto:
> > No, <on_crash> is the right thing to be using for this from
> > libvirt's pov & I don't think we should invent something new.
> > The <on_crash> element has always been intended to represent
> > handling of guest panics, not qemu internal errors.
> 
> Actually for Xen HVM guests, it mostly traps things such as failed
> vmentries.  The Xen PV-on-HVM drivers do not register a panic notifier
> that moves the guest to the "crashed" state.
> 
> <on_crash> cannot be salvaged, in my opinion, because all domain XMLs in
> the wild will have a setting that causes libvirt to add "-device
> isa-pvpanic".  Thus changing libvirt versions will change guest
> hardware, which is _very_ bad.
> 
> In addition, Windows XP and 2003 will show the annoying device wizard
> upon a libvirt upgrade, and fixing this is what surfaced all the mess.

The existance of a <on_crash> element should not be having any
effect on what hardware we create. That is merely a lifecycle
policy setting that should be completely independant of the
guest device model.

eg it is valid to have <on_crash> present in the XML at all
times, even if there's no pvpanic device present. That simply
means the actions will never be triggered.


Daniel
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