Re: [Xen-devel] [PATCH 5/5] AMD IOMMU: widen NUMA nodes to be allocated from

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 03/10/2015 03:35 AM, Jan Beulich wrote:
> > > > On 09.03.15 at 20:02, <suravee.suthikulpanit@xxxxxxx> wrote:
> > I agree that having the IO page tables on the NUMA node that is closest
> > to the IOMMU would be beneficial.
> And I already withdrew this patch and the corresponding VT-d one.
>
> > However, I am not sure at the moment
> > that this information could be easily determined. I think ACPI _PXM for
> > devices should be able to provide this information, but this is optional
> > and often not available.
> And even if it was available, it would be too late at least for Dom0's
> allocations (as it requires Dom0's interpreter to dig out this detail).
> The best we could do in that case would be to try to replace the
> existing tables. Or assume Dom0 is being placed suitably by the
> dom0_nodes= option. Or add yet another option.
There is a nodeID register on each northbridge (D1<x>F0x60). You would 
have to figure out how to map it to _PXMs though.
-boris


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