Hi,

I'm trying to install Gentoo on an AMD K6-III system -- successfully -- until 
I noticed that the ebuild for xine-lib-0.9.13-r3 had changed my -march=k6-3 
to i686 and libpng changed it to i586.

I understand why this is done, but I thought that a k6-III was equivalent to 
i586, and built my system (from stage 1) with CHOST="i586-pc-linux-gnu".

I know I can't use CHOST="k6-3-pc-linux-gnu" (at least in part because the 
extra '-' confuses the parsing) because I've tried on my Mandrake 9.1 :-) but 
should I use the default CHOST="i686-pc-linux-gnu" instead?

Gcc info page doesn't help;
> `-mcpu=CPU-TYPE'
>      Tune to CPU-TYPE everything applicable about the generated code,
>      except for the ABI and the set of available instructions.  The
>      choices for CPU-TYPE are `i386', `i486', `i586', `i686',
>      `pentium', `pentium-mmx', `pentiumpro', `pentium2', `pentium3',
>      `pentium4', `k6', `k6-2', `k6-3', `athlon', `athlon-tbird',
>      `athlon-4', `athlon-xp', `athlon-mp', `winchip-c6', `winchip2' and
>      `c3'.
> 
>      While picking a specific CPU-TYPE will schedule things
>      appropriately for that particular chip, the compiler will not
>      generate any code that does not run on the i386 without the
>      `-march=CPU-TYPE' option being used.  `i586' is equivalent to
>      `pentium' and `i686' is equivalent to `pentiumpro'.  `k6' and
>      `athlon' are the AMD chips as opposed to the Intel ones.
> 
> `-march=CPU-TYPE'
>      Generate instructions for the machine type CPU-TYPE.  The choices
>      for CPU-TYPE are the same as for `-mcpu'.  Moreover, specifying
>      `-march=CPU-TYPE' implies `-mcpu=CPU-TYPE'.
second paragraph, last sentence seems not to have been updated for a while...

I've seen a version of make.conf (quoted in a forum) 
http://forums.gentoo.org/viewtopic.php?t=89058&sid=d4c287758d27febac037f44b2b3e0c19
that says
> All K6's are i586.
-- but xine-lib leads me to doubt this -- and mine just says;

# If you are using a Pentium Pro or greater processor, leave this line as-is;
# otherwise, change to i586, i486 or i386 as appropriate. All modern systems
# (even Athlons) should use "i686-pc-linux-gnu".

I thought the Pentium Pro was a dead-end, and that the Pentium II was based on 
the Pentium.  Can I infer from "All modern systems (even Athlons)", that k6* 
_shouldn't_ use "i686-pc-linux-gnu" ?  If so, why am I able to compile with 
-march=i686?

I'm confused and worried that Im not giving this old nag free rein.

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