Re: [Xen-devel] [PATCH 3/3] x86/AMD-Vi: Fix IVRS HPET special->handle override

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.09.13 at 18:48, Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> 
>>> wrote:
> I am a bit confused on what you want to do.  I believe all the systems 
> at this point
> should have only one HPET.  That's why the code only has one data 
> structure for
> initialize one HPET.  Are you expecting that certain systems could have 
> more than
> one HPETs?

Of course. The code assuming just one HPET is wrong in the first
place, so I'm really not looking towards making matters worse.
The only valid a priori information we have is that there's
exactly one HPET nominated as the legacy replacement one
(through the ACPI HPET table), but there could be more (as
said, this is quite likely on multi-node NUMA systems).

> Alternatively, I can try matching on the "SBDF" assuming that IVRS 
> doesn't screw up
> the SBDF part of the HPET special entry.

As long as we only support one, we should be prepared for
either ID or SBDF to be wrong, and should (for maximum
flexibility) probably allow matching in both directions. Or you'd
need to propose a new way of associating the IOMMU with
the HPET.

Jan


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