On Mon 2008-08-18 07:58:03, David Fries wrote:
quoted text
> On Mon, Aug 18, 2008 at 05:14:50AM +0100, Maciej W. Rozycki wrote:
> > On Sun, 17 Aug 2008, David Fries wrote:
> > > +	/* cr4 was introduced in the Pentium CPU */
> > 
> >  NACK.  Later i486 chips do have CR4 -- for PSE, VME, etc. (the set of
> > features varies across the line).  Use a fixup as elsewhere or something.

quoted text
> 
> That's what I get for reading the Intel instruction set reference,
> "The CR4 register was added to the Intel Architecture beginning with
> the Pentium processor."
> 
> Ingo Molnar, thanks, I'll try the read_cr4_safe() version tonight (the
> computer is in the trunk of my car and I'm about ready to head to
> work).
> 
> In light of the above, how about updating the comments
> -       /* cr4 was introduced in the Pentium CPU */
> -       jecxz   1f      # cr4 Pentium and higher, skip if zero
> +       /* cr4 not in i386 only some i486, skip if zero */
> +       jecxz   1f      # cr4 not in i386 only some i486, skip if zero

Okay, can it happen that that cr4 is zero legitimately? If newer 486SX
chips support cr4 but not coprocessor...?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/