Re: Folding _PAGE_PWT into _PAGE_PCD (was Re: unify pagetable accessors patch causes double fault II)

Jeremy Fitzhardinge
2008-01-15T17:33:19Z

Andi Kleen wrote:
>> BTW, I just noticed that _PAGE_PWT has been folded into _PAGE_PCD. This
>> seems like a really bad idea to me, since it breaks the rule that
>> _PAGE_X == 1 << _PAGE_BIT_X. I can't think of a specific place where
>> this would cause problems, but this kind of non-uniformity always ends
>> up biting someone in the arse.
>>
>
> Agreed that it's a bad idea.
>
>
>> I think having a specific _PAGE_NOCACHE which combines these bits is a
>> better approach.
>>
>
> CPA series adds that already
>
> +/* Needs special handling for large pages */
> +#define _PAGE_CACHE (_PAGE_PCD|_PAGE_PWT|_PAGE_PAT)
>

Good, but isn't the name _PAGE_CACHE misleading? Or does it mean
something else in the context of PAT?

J