Re: How to compose kernel makeoptions

[Chuck Swiger <cswiger%mac.com@localhost>]

On Feb 25, 2011, at 5:25 PM, charles wrote:
> so i guess i can ignore/not worry about the makeoptions line in the config 
> or/and add "-march=pentium3"
> 
> and if that's so ... well it was strange to see the new option as a 
> makeoption instead of what is was before, so i'm making something out of 
> nothing perhaps.

Well, you're welcome to try your own benchmarks and see for yourself whether 
there is a meaningful difference for your workload.  :-)

> where do i find the march definitions? is there a master list?

-march=native is easier than processing the whole list, but "man cc" (or "info 
gcc", perhaps) will give you a huge long list which starts:

           i386
               Original Intel's i386 CPU.

           i486
               Intel's i486 CPU.  (No scheduling is implemented for this chip.)

           i586, pentium
               Intel Pentium CPU with no MMX support.

           pentium-mmx
               Intel PentiumMMX CPU based on Pentium core with MMX instruction
               set support.

           pentiumpro
               Intel PentiumPro CPU.

           i686
               Same as "generic", but when used as "march" option, PentiumPro
               instruction set will be used, so the code will run on all i686
               family chips.

           pentium2
               Intel Pentium2 CPU based on PentiumPro core with MMX instruc-
               tion set support.

           pentium3, pentium3m
               Intel Pentium3 CPU based on PentiumPro core with MMX and SSE
               instruction set support.
[ ...and then wanders off into P4/Prescott/Nocona, AMD Athlon/Opteron, VIA C3, 
etc... ]

Regards,
-- 
-Chuck