[devel] i686: CPUs at stake

[Alexey Tourbin <at@altlinux.ru>]

On Wed, Mar 02, 2011 at 03:52:16AM +0300, Alexey Tourbin wrote:
> Важно разобраться, какое именно железо стоит на кону.

Nick Lowe	2011-02-16
https://bugzilla.redhat.com/show_bug.cgi?id=579838#c46

Now that binutils has been fixed, i686 is a sane baseline for a 32-bit build.
In my view, the entire 32-bit build of FC15 should be targeted for i686 with
-march=i686 with a fixed version of binutils (GAS) that does not make bad
assumption over the presence of NOPL.

As far as compatibility impact of compiling for i686, which need to be
understood and digested:

VIA Edens based on the 'Samuel 2' design do not support CMOV or NOPL. (These
would break.)
All VIA Edens based on the 'Nehemiah' design support CMOV but not NOPL.
(Introduced in 2003. These would not break.)

Via C3s based on the 'Samuel 2'or 'Ezra'/'Ezra-T' design do not support CMOV or
NOPL. (These would break.)
All C3s based on the 'Nehemiah' design support CMOV but not NOPL. (Introduced
in 2003. These would not break.)

National Semi's GXm, GXLV and GX1 do not support CMOV or NOPL. (These would
break.)
All Geodes since and including National Semi's GX2 support CMOV but not NOPL.
(Introduced in 2002. These would not break.)
The AMD branded Geodes (GX and LX) support CMOV but not NOPL. (These would not
break.)

The Cyrix 6x86 processors do not support CMOV or NOPL. (These would break.)
The Cyrix 8x86MX / Cyrix MII do support CMOV but not NOPL. (These would not
break.)

The AMD K6 and K6-2 do not support CMOV or NOPL. (These would break.)