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

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jun 26, 2014 at 03:30:11PM +0200, Paolo Bonzini wrote:
> Il 26/06/2014 13:36, Michael S. Tsirkin ha scritto:
> >>It should be this way in real hardware too
> >But it isn't.
> 
> That's why I mentioned that this hack should become architecturally
> specified (since it can work on real hardware too)

Someone will have to implement it on real hardware first :)
As long as no one does it's really PV.
I have no problem with PV as such, however
1. let's try to make it look less like a one-off hack
2. let's start with proper emulation, pv as step 2

> with QEMU doing the
> emulation for current-generation devices.
> 
> >> (not exactly _this_ hack, but at least no improper relationship among
> >> IGD/MCH/PCH).
> >
> >Well that dependency between devices is common for embedded hardware,
> >and this is what we have here.
> 
> Sure, but then you should put MCH/PCH/IGD in the same IOMMU group, which
> basically means forgetting about IGD assignment.
> 
> Paolo

I don't see why. We emulate parts of devices (e.g. BARs), ISA bridge/MCH is just
such part of device that we emulate.


-- 
MST