Messages in this thread | | | Date | Thu, 15 Jan 2009 09:57:28 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86: simplify HIGHMEM-related Kconfig entries |
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* Jan Beulich <jbeulich@novell.com> wrote:
> >>> "H. Peter Anvin" <hpa@zytor.com> 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.
There's no deep reason, it just has never really been tested that way. I think we should try it.
Ingo
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