lkml.org 
[lkml]   [2007]   [Jan]   [4]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateThu, 4 Jan 2007 02:11:42 -0500
From"Albert Cahalan" <>
SubjectRe: kernel + gcc 4.1 = several problems
Linus Torvalds writes:
> [probably Mikael Pettersson] writes:

>> The suggestions I've had so far which I have not yet tried:
>>>> - Select a different x86 CPU in the config.>>   - Unfortunately the C3-2 flags seem to simply tell GCC to
>>     schedule for ppro (like i686) and enabled MMX and SSE
>>   - Probably useless>> Actually, try this one. Try using something that doesn't like "cmov".
> Maybe the C3-2 simply has some internal cmov bugginess.

Of course that changes register usage, register spilling,
and thus ultimately even the stack layout. :-(

Adjusting gcc flags to eliminate optimizations is another way to go.
Adding -fwrapv would be an excellent start. Lack of this flag breaks
most code which checks for integer wrap-around. The compiler "knows"
that signed integers don't ever wrap, and thus eliminates any code
which checks for values going negative after a wrap-around. I could
imagine this affecting a switch() or other jump table.
-
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/

\
 
 \ /
  Last update: 2007-01-04 07:15    [W:0.549 / U:0.040 seconds]
©2003-2008 Jasper Spaans