Re: [Qemu-devel] [Xen-devel] [v5][PATCH 0/5] xen: add Intel IGD passthrough support

[Chen, Tiejun]

On 2014/7/2 14:11, Michael S. Tsirkin wrote:
> On Tue, Jul 01, 2014 at 03:29:03PM -0400, Ross Philipson wrote:
> > On 07/01/2014 02:06 PM, Michael S. Tsirkin wrote:
> > > On Tue, Jul 01, 2014 at 01:39:04PM -0400, Ross Philipson wrote:
> >
> > [snip]
> >
> > > What class does your ISA bridge device have?
> >
> > #define PCI_CLASS_BRIDGE_ISA             0x0601
>
> Okay I guessed so. But IIRC Tiejun's suggesting giving it a different

Organically we really use this class. But Paolo said this introduce two 
ISA bridges, then something will be confused. Sorry I can't find that 
quickly since we have so long discussion, so long email thread :(

Thanks
Tiejun

> class. So we don't know what the effect will be on various guests
> without testing.
>
>
> > > > > > Also I don't like the idea of tying Tiejun's patch series, that covers a
> > > > > > very narrow use case, to something as important and general purpose as
> > > > > > upgrading chipset.
> > > > >
> > > > > If it's true that implementing igd passthrough on top of q35 is much
> > > > > cleaner architecturally, then I don't see why we should merge a stop-gap
> > > > > solution that we'll need to then support indefinitely.
> > > > >
> > > > > We are talking about upstreaming functionality that xen already has, right?
> > > > > So there's no time to market concern, whoever wants a solution today
> > > > > has it.  Why not do it in the cleanest possible way?
> > > >
> > > >
> > > > --
> > > > Ross Philipson
> > >
> > > -----
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> >
> >
> > --
> > Ross Philipson