Re: Loss of PAT-WC after resume on i5

From: H. Peter Anvin
Date: Mon Jan 03 2011 - 12:31:53 EST

On 01/03/2011 08:21 AM, Chris Wilson wrote:
> On Mon, 03 Jan 2011 08:01:05 -0800, "H. Peter Anvin" <hpa@xxxxxxxxx> wrote:
>> Sounds like it. It sounds based on your description that it's something
>> more fundamental than just the state of the PAT MSR being lost, too,
>> although perhaps that's the first thing to check...
> Right, I should have mentioned that a rdmsr(MSR_ISA32_CR_PAT) showed no
> change across a dysfunctional resume. And that
> /sys/kernel/debug/x86/pat_memtype_list had the same contents (just the
> first entries reversed upon resume).

OK, this is doubly strange: both that entries would have change order
and that they would not be active, if the PAT MSR is set correctly.
That would imply that the page tables are somehow corrupt, which seems
like a scary concept.


H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at