Re: [PATCH] [RFC] x86: work around MPX Erratum

From: Linus Torvalds
Date: Tue May 03 2016 - 17:33:08 EST

On Tue, May 3, 2016 at 2:28 PM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
>> So we won't init MPX on those...
> Yes, and as long as such a processor doesn't exist today and never
> exists in the future or the folks that buy such a processor truly don't
> care about MPX, that's fine to do. I'm just a bit nervous about the
> whole "never exists in the future" part.

I don't think we need to care.

If a CPU doesn't support SMEP, there really is no reason for us to
ever support MPX either.

It's not like there is a clamoring for MPX support in the first place
(have you ever heard of anybody actually asking for or using it?), and
quite frankly, it's a _lot_ more complicated from a CPU core side than
SMEP (which is trivial).

So if Intel ever releases a CPU with MPX but without SMEP, nobody will
ever care about the MPX part being useless.