Re: [GIT pull] x86 mpx support for 3.19

[H. Peter Anvin]

On 12/10/2014 12:49 PM, Linus Torvalds wrote:
> On Wed, Dec 10, 2014 at 12:39 PM, Dave Hansen
> <dave.hansen@xxxxxxxxxxxxxxx> wrote:
>>
>> I misspoke there.  I meant SMAP (I placed MPX below its config option).
> 
> Ok, I agree on SMAP, we might want to have that be configurable too,
> especially for smaller systems (I *think* SMAP is big-core only,
> right?). I'm not sure how much of a possible performance downside it
> has, but it does add instructions to potentially critical areas.
> 

*As far as I know*, SMAP will be pushed into all CPUs over time.

SMAP is already configurable, although the overhead on non-SMAP-enabled
hardware is minimal (the CLAC/STAC instructions get patched out.)

	-hpa


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