Re: [PATCH] x86: simplify HIGHMEM-related Kconfig entries

From: Jan Beulich
Date: Thu Jan 15 2009 - 03:53:00 EST


>>> "H. Peter Anvin" <hpa@xxxxxxxxx> 14.01.09 20:39 >>>
>Jan Beulich wrote:
>> Additionally remove the dependency of X86_PAE on !HIGHMEM4G - at least
>> I can't understand why that dependency existed.
>
>At least originally, the meaning of the x86 highmem entries were:
>
> No highmem - No highmem, no PAE
> HIGHMEM4G - Highmem, no PAE
> HIGHMEM64G - Highmem, PAE
>
>So X86_PAE and HIGHMEM4G is a bit of a contradiction. I haven't looked
>at the logic in detail, or remember offhand if there have been any
>weakening of the definitions above; e.g. someone could have implemented
>a way to do PAE without highmem, to get access to the NX bits.

Exactly - .23 made PAE an independently selectable option (in particular,
the no-highmem+PAE combination is now valid), but I can't see why it
added the !HIGHMEM4G dependency.

Jan

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