Re: pud_bad vs pud_bad

From: Ingo Molnar
Date: Thu Feb 05 2009 - 16:51:19 EST



* Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

>> I sincerely hope 0! I shed no tears at losing support for NUMAQ, but why
>> should we be forced to double all the 32-bit ptes? You want us all to be
>> using NX? Or you just want to cut your test/edit matrix - that I can
>> well understand!
>
> Yes, that's the gist of it. We could simplify things by having only one
> pte format and only have to parameterise with 3/4 level pagetables. We'd
> lose support for non-PAE cpus, including the first Pentium M (which is
> probably still in fairly wide use, unfortunately).

We'd also lose a fair bit of performance (not to mention the pagetable
footprint doubling that Hugh already mentioned) on 32-bit PAE capable
systems that dont actually have RAM above 4G physical.

Bad idea really ...

Ingo
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