[CLUE-Tech] Athlon = i686 in kernel 2.4.7 Makefile

[Timothy C. Klein]

* Jed S. Baer (thag at frii.com) wrote:
> On Sun, 24 Mar 2002 13:58:31 -0700
> Dave Anselmi <anselmi at americanisp.net> wrote:
> 
> > "Jed S. Baer" wrote:
> > 
> > > Hi Folks.
> > >
> > > I think this is the last strangeness from the RH7.2 upgrade. Searching
> > > through the kernel mailing list archive, I see speculation on why make
> > > would write -march=i686 instead of march=athlon, 
> > 
> > IIRC, gcc 2.x doesn't have athlon support.  gcc 3.x is the first place
> > that option shows up.  Now, should you use i586, i686, or k6?  I don't
> > know and I've never found a discussion of how to decide.
> 
> Well, I did test whether the compiler supports athlon. At least it doesn't
> complain about it. I get an error message from gcc -march=foobar, but not
> gcc -march=athlon. This was even before the upgrade to RH7.2. Could be
> that RH patches the compiler to support it? The kernel mailing list
> postings I found all argued against using k6, as i686 is much closer to
> athlon capabilities.
> 

Isn't the 2.96 that comes with Redhat the 3.0 prerelease?  If so, it
would support athlon as an arch.  And I would definetly say use i686
rather than K6 if you can't use Athlon.  However, I looked through
kernel makefiles, and it *does* support arch Athlon if your compiler
supports it, it would seem.  At least in 2.4.18.  It does a test to see
of -march=athlon is accepted, and if not, it uses -march=686.

I usually compile with gcc 2.95 on Debian Sid, which is the default.
However, if I edit the top-level kernel Makefile to use gcc-3.0, I have
support for the -march=athlon flag, and the kernel Makefiles are using
it automatically.  The kernel folks say that gcc 3.0 is dangerous,
though.  It is currently compiling now, I guess I will find out if
compiles all the way to the end.

Then, the real test will be to benchmark my current i686 arch kernel
versus the new athlon arch kernel, and see if there is a difference.
And if the gcc-3.0 version crashes on me :-)

Tim
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