Re: [PATCH v2 2/6] x86, mm, pat: Change reserve_memtype() to handle WT

[Andy Lutomirski]

On Wed, Sep 10, 2014 at 1:14 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 09/10/2014 12:30 PM, Toshi Kani wrote:
>>
>> When WT is unavailable due to the PAT errata, it does not fail but gets
>> redirected to UC-.  Similarly, when PAT is disabled, WT gets redirected
>> to UC- as well.
>>
>
> But on pre-PAT hardware you can still do WT.
>

Using MTRRs?  /me shudders, although I suppose this would be okay for
NV-DIMMs as long as you map the whole thing WT.

One of these days I'll finish excising mtrr_add from everything
outside arch/x86.  I already killed it in all modern graphics drivers
:)

--Andy



>         -hpa
>



-- 
Andy Lutomirski
AMA Capital Management, LLC
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