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

[H. Peter Anvin]

On 09/10/2014 02:27 PM, Andy Lutomirski wrote:
>>
>> That's possible, but the only benefit is that we can enable WT on
>> pre-PAT systems, which I do not think anyone cares now...  WB & UC work
>> on pre-PAT systems.  WC & WT need PAT.  I think this requirement is
>> reasonable.
> 
> It might end up being a cleanup, though.  A whole bunch of
> rarely-exercised if (!pat_enabled) things would go away.
> 

Yes.  Don't think of it as PAT vs non-PAT.  Think of it as a specific
set of cache types available on different processors.  The fact that you
may have to frob an MSR to initialize it is almost trivial in comparison.

	-hpa


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