Re: x86 status was Re: -mm merge plans for 2.6.23

From: Ingo Molnar
Date: Wed Jul 11 2007 - 20:28:56 EST



* Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:

> > i dont think "clean, modern x86 code" will ever happen - x86_64 has
> > and is going to have the exact same type of crap. And i'll say a
> > weird thing
>
> Yes, but it will be new crap, but no old crap anymore.
>
> If you always pile the new crap on the old crap at some point the
> whole thing might fall over. 64bit was intended as a fresh start.

I think there's no such thing as a fresh start for a diverse
architecture - the ia64 failure has proven that. x86_64 CPUs still do
A20 emulation today (!). We still have people running industrial boards
on real i386 DX CPUs, with the latest upstream kernel. 15 years ago an
i386 DX was already quite obsolete. 32-bit is not going to go away in
our lifetime, and we'll want to support it in a first-grade way. We
better realize that prospect and have it right before our eyes in a
single tree wherever it makes sense to share code - i'm certainly not
talking about sharing mtrr/centaur.c or k8.c. (and i'm not necessarily
suggesting to share io_apic.c either - although it's certainly
borderline.)

Ingo
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