Re: [patch 0/4] x86: PAT followup - Incremental changes and bug fixes

H. Peter Anvin
2008-01-17T20:43:49Z

Ingo Molnar wrote:
> * Andreas Herrmann3 <andreas.herrmann3@amd.com> wrote:
>
>> For the failed devices I get:
>>
>> sata_sil 0000:00:12.0: version 2.3
>> ACPI: PCI Interrupt 0000:00:12.0[A] -> GSI 22 (level, low) -> IRQ 22
>> ioremap_nocache: addr c0403000, size 200
>> swapper:1 conflicting cache attribute c0403000-c0404000 uncached<->default
>> ACPI: PCI interrupt for device 0000:00:12.0 disabled
>
> hm, is the problem that the two devices share the same physical page,
> and thus get an overlapping area?
>
> as an intermediate fix, how about following the attribute of the already
> existing mapping, instead of rejecting the ioremap due to the conflict?
> I.e. something like below?

The correct behaviour probably would be to go with the most restrictive
caching behaviour, i.e. uncached in this case.

-hpa