Re: [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata

Andi Kleen
2003-09-11T14:26:38Z

On Thu, 11 Sep 2003 10:15:25 -0400
Jeff Garzik <jgarzik@pobox.com> wrote:

> Andi Kleen wrote:
> > It could be done but ... we are moving more and more to generic kernels
> > (e.g. see the alternative patch code which is enabled unconditionally)
> > So that when you have a kernel it will boot on near all modern CPUs.
>
>
> Only with CONFIG_X86_GENERIC. That's precisely why CONFIG_X86_GENERIC
> was created.

It was not created for that (I know that because I created it ;-)

X86_GENERIC is merely an optimization hint (currently it only changes the cache
line size hint) It does not change anything related to correctness. Everything
that handles correctness is checked unconditionally.

is_prefetch is a correctness thing.

>
> If I disabled CONFIG_X86_GENERIC and select CONFIG_MPENTIUM4, I darned
> well better not get any Athlon code. The cpu setup code in particular I
> want to conditionalize, and there are other bits that need work... but
> for the most part it works as intended.

Now that's becomming silly. It's alttogether only a few KB and all
__init code anyways.

-Andi