Re: [Qemu-devel] [PATCH 4/4] xen: Fix PV-on-HVM

[Michael S. Tsirkin]

On Wed, May 16, 2012 at 10:06:25AM +0200, Paolo Bonzini wrote:
> Il 15/05/2012 23:00, Michael S. Tsirkin ha scritto:
> > On Tue, May 15, 2012 at 04:26:39PM +0100, Anthony PERARD wrote:
> >> In the context of PV-on-HVM under Xen, the emulated nics are supposed to be
> >> unplug before the guest drivers are initialized. This mean that there must 
> >> be
> >> unplug without the consent of the guest.
> >>
> >> Without this patch, the guest end up with two nics with the same MAC, the
> >> emulated nic and the PV nic.
> >>
> >> Signed-off-by: Anthony PERARD <address@hidden>
> > 
> > OK, so on Xen there are special devices that can be safely removed
> > without telling the guest?  Does there need to be regular hotplug for
> > these devices too? Or can it be always surprise removal?
> 
> On Xen the PV drivers can ask the firmware to surprise-remove the
> emulated NICs.

So driver tells firmware (meaning acpi? how?) that it's ok
to do surprize removal?

> Of course it has to do it early enough so that the guest
> doesn't crash.
> 
> Paolo

What does early enough mean and how do we ensure that?

-- 
MST