Re: RFC: [2.6 patch] better i386 CPU selection

[Adrian Bunk <bunk@fs.tum.de>]

On Sun, Sep 07, 2003 at 07:09:49PM +0100, Alan Cox wrote:
>...
> > I'm not sure if an Athlon is "lower" than a PII or not....  Which do I
> > option do I pick, to run on either of those without including
> > redundant stuff for older CPUs?
> 
> Right now its ordered
> 
> 386 - 486 - 586 - 586+TSC - 686 - PPro - PII - PIII - PIV
> 
> Geode is a branch off 586+TSC and supports 686+ too
> Athlon branches off from PIII if I remember rightly
> Winchip branches off from 586 and supports all later x86 too
> ELAN is its own weird world
> Xmeta comes off 686 somewhere depending how you handle PGE

x86 is a complicated family...

My current list of CPU specific questions is:

- Does the Cyrix III support 686 instructions?
- Do -march=winchip{2,-c6} and -march=c3{,-2} add anything not in
  -march=i686 (except optimizations of otherwise compatible code)?
- Which CPUs exactly need X86_ALIGNMENT_16?
- X86_GOOD_APIC: Are there really that many processors with a bad APIC?

TIA
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed