Re: [v1 1/2] xen/p2m: Create identity mappings for PFNs beyound E820 and PCI BARs

Konrad Rzeszutek Wilk
2013-10-29T14:46:46Z

On Tue, Oct 29, 2013 at 08:23:30AM +0000, Jan Beulich wrote:
> >>> On 28.10.13 at 17:58, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:
> > On Fri, Oct 25, 2013 at 04:08:19PM -0600, Bjorn Helgaas wrote:
> >> If you can look at PCI host bridge apertures instead of BARs, that
> >> would solve both problems. Reassigning those apertures is
> >> theoretically possible but is not even a gleam in our eyes yet.
> >
> > <nods> I think I have to have both (BARs and host bridge apertures) as when
> > we do PCI passthrough to a guest - we might do it without a bridge.
>
> Why? Aren't the host bridge ranges necessarily a superset of the
> individual devices' BARs?

Yes. But when you pass in a PCI device to a PV guest you don't pass in the
bridge. Just the PCI device itself.

>
> Jan
>