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

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

On Mon, Jun 30, 2014 at 01:18:51PM +0200, Paolo Bonzini wrote:
> Il 30/06/2014 12:20, Chen, Tiejun ha scritto:
> >
> >I already post this to mainline to change as follows:
> >
> >-    while ((pch = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, pch))) {
> >+    pch = pci_get_bus_and_slot(0, PCI_DEVFN(0x1f, 0));
> >+    if (pch) {
> >
> >Please refer to this,
> >
> >[RFC][PATCH] gpu:drm:i915:intel_detect_pch: back to check devfn instead
> >of check class type
> >
> >Linux Native guys would like to accept this. And actually Windows always
> >use devfn to detect this.
> 
> Fair enough, but that means that, when using IGD, Q35 will have to move the
> ISA bridge off 1f.0.
> 
> To me it seems fairly clear that as things stand IGD is not virtualizable
> without PV support.  We're beating a dead horse.
> 
> Paolo

It seems virtualizeable without PV.  Virtualizing it just requires
emulating a chipset that's closer to what the driver expects,
which seems to be more effort than Tiejun is prepared to put in.

-- 
MST