Re: [Xen-devel] [PATCH 3/3] qemu-xen-trad: IGD passthrough: Expose vendor specific pci cap on host bridge.

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Tue, Jul 16, 2013 at 01:55:20AM +0300, Pasi Kärkkäinen wrote:
> > >>How was that diagnosed? Perhaps that information can be part of the source
> > >>code to help in the future with diagnosiing which caps are needed and
> > >>which ones can be blacklisted?
> > >>
> > >
> > >I guess that's a question mostly for Ross/Jean as they're the original 
> > >authors of the patch?
> > 
> > We discovered the issue with Windows guests running the vendor
> > drivers for the passed in IGD graphics device. Under certain
> > circumstances (resuming from S3/S4 IIRC), the guest would BSOD. I
> > finally tracked it down to a bad state in the resuming driver
> > because it was not coded to handle the vendor capabilities not being
> > present on the host bridge. BTW, those capabilities are flags
> > indicating what features the IGD card has - their exact meaning is
> > of course proprietary.
> > 
> > I cannot say it was only a problem on Windows but rather that that
> > is the only place we ever saw it.
> > 
> > I never saw any other capabilities on the hosts bridges at that
> > time, just vendor ones so the patch just handled that. If there were
> > other capabilities, I would think it would have to be determined on
> > a case by case basis whether they were included. Inclusion of each
> > new type would have different ramifications it seems.
> > 
> 
> Thanks for the explanation. I guess parts of that should go to the patch 
> description aswell..
> 

Now patch 2/3 has been applied to qemu-traditional, so only this patch 3/3 is 
missing from qemu-traditional from this series.

Any other changes outstanding? or only to add some of Ross's comments to the 
patch description (and/or sources) ? 

Thanks,

-- Pasi


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