Re: [RFC/PATCH 00/59] Make common x86 arch area for i386 and x86_64

From: Andi Kleen
Date: Wed Mar 14 2007 - 06:12:45 EST


On Tue, Mar 13, 2007 at 02:39:33PM -0700, Linus Torvalds wrote:
>
>
> On Tue, 13 Mar 2007, Steven Rostedt wrote:
> >
> > What we have currently is a bunch of hacks. Seems that people can't make
> > up their mind to what to do.

I think they work fine. I don't like such large scale renaming -- they
are a pain for anybody with external patches and make regression hunting
later painful. And the gain is about zero as far as I can see.
It won't fix a single bug, just cause pain.

>
> I don't mind the patches, but I'd be a lot happier if it also was a stated
> intention to actually make it be buildable as "x86", the same way that the
> separate 32-bit and 64-bit POWER architectures were merged into just one
> architecture that could be built either way.

I've thought about it, but it would be a lot of work and regression
test on old hardware would be a nightmare.

Besides still x86-64 is a lot cleaner than i386 and imho
easier to hack and with all the 32bit quirks readded it would probably
become worse than current i386. The only good option would be
a "modern 32bit only" but even that gets complicated quickly when
you consider all the corner cases. And a clean 32bit port wouldn't
cover enough hardware to be usable by distributions.

And I also don't have really time to work on that.

> The "32-bit code has legcay issues" thing that Andi complained about (eg
> there's no guarantee of a HPET on 32-bit x86) doesn't really change the

Most 64bit doesn't neither.

> fact that yes, we have to support those legacy issues *anyway*, and 64-bit
> x86 certainly has its set of issues already too.

Yes :/ The more supported systems, the more junk.

The recent nmi watchdog issues are a good example. All just because
a few vendors write crappy AML/SMM code.

> We've started to notice that the i386 build gets broken now that most
> developers tend to have newer CPU's and run mostly on x86-64 (and yes,
> that's me too), and while I don't think unifying things will guarantee
> that doesn't happen in the future, it will hopefully at least help make it
> not get much *worse*.

Build test would be needed anyways, doesn't make much difference I guess.

> As it is, the build environment has to know to pass in "-m32/-m64"
> anyway..

It already does that.

-Andi

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