Re: [RFC][PATCH 02/22] x86,mmx_32: Remove .fixup usage

Borislav Petkov
2021-11-04T18:00:54Z

On Thu, Nov 04, 2021 at 05:47:31PM +0100, Peter Zijlstra wrote:
> This code puts an exception table entry on the "PREFIX" instruction to
> overwrite it with a jmp.d8 when it triggers an exception. Except of
> course, our code is no longer writable, also SMP.
>
> Replace it with ALTERNATIVE, the novel
>
> XXX: arguably we should just delete this code

Yah, might as well.

Wikipedia says the last AMD CPU which supports 3DNow is A8-3870K which
is family 0x11, i.e.,

1. a real rarity
2. it is pretty much obsolete
3. even if not, it can do AMD64
4. and even if people who have it, wanna run 32-bit, they can use the
normal memcpy, i.e., CONFIG_X86_USE_3DNOW=n should work there

In our case, it is a bit different, though:

config X86_USE_3DNOW
def_bool y
depends on (MCYRIXIII || MK7 || MGEODE_LX) && !UML

MK7 is K7 - that is practically dead.

The only thing I have no clue about are those cyrix and geode things and
whether they're still actively used in some embedded gunk.

--
Regards/Gruss,
Boris.