Re: [git pull] x86 fixes

Linus Torvalds
2008-09-09T16:16:19Z

On Tue, 9 Sep 2008, Adrian Bunk wrote:
>
> We use 3DNow! for bigger memcpy's if the kernel is configured for a K7.
>
> How does this fit into your picture?

It doesn't. I guess I don't care that much, since explicitly asking for
some odd-ball case does indicate that you want a very specific kernel. I
guess that's ok. I'm certainly not violently against it.

Of course, I also suspect that we _could_ fix it so that things like
memcpy really only have two cases:

- the special inlined "rep movs" thing. Although I'm not actually sure
gcc even does this, and I don't think we force it any more.

- If doing a function call, we could just fix things up to be more
dynamic. Of course, the fixups for the SMP cases are scary (ie we'd
probably have to first change it to a one-byte "int $3" instruction,
then change the target, and then write the first byte back - and handle
any race with another CPU by fixing up the trap).

but I dunno.

Linus