Re: 2.6.26-rc6-git2: Reported regressions from 2.6.25

Maciej W. Rozycki
2008-06-15T23:33:48Z

On Sat, 14 Jun 2008, Linus Torvalds wrote:

> > From what you have written it looks the dependency should actually be:
> >
> > depends on !M386 && !M486 && !M586 && !M586TSC && !M586MMX
> >
> > as none of the pre-Pentium-Pro processors had the PAE feature (I am not
> > sure about non-Intel implementations, so the case of M586 would have to be
> > investigated).
>
> Yes, it's the non-intel ones that would keep me from saying !M586.
>
> For intel, PAE was a PPro feature (at least officially, as you point out),
> but I do not know about various other manufacturers. From personal
> experience, the line between Pentium and PPro features doesn't tend to be
> totally black-and-white (although I suspect that when it comes to PAE it
> _may_ be).

Well, PAE is quite a significant block to implement and Intel kept it
hidden until they published the long awaited PentiumPro manual sometime in
1996. I am fairly sure the K5 did not implement it (it may have had PSE
and VME, especially in the later revisions) and Google does not show up
any Cyrix processors with PAE. I may have a K5 manual somewhere, so I can
see if I can verify it.

Please also note these processors tried to compete with Intel on the
desktop market where 4GB of RAM was completely unreasonable in late 90s.
I think unless someone can recall a counter-example, it can be safely
assumed these chips did not have the PAE. We could try to extend the
dependency and see if anybody screams.

Maciej