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

[Dave Jones <davej@redhat.com>]

On Mon, Jun 16, 2008 at 12:31:52AM +0100, Maciej W. Rozycki wrote:
 > 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.

Even the K6 didn't have PAE.  The Athlon was AMD's first CPU that had 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.
 
I agree.  To the best of my knowledge (and looking through output of
x86info from lots of old CPUs), Intel had the only CPUs with PAE in
that era.

	Dave

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