Re: P6 NOPs again: MPSC?

H. Peter Anvin
2008-03-11T06:54:00Z

Hugh Dickins wrote:
>
> Yup, I realized that (with || in place of &&): I meant that perhaps
> it was supposed to say X86_64 || (!X86_GENERIC && (M686 || ....))
> since quite a lot of other options there have "|| X86_64" to cover
> all the 64-bit possibilities at once i.e. is it only MPSC that
> needs to be added, or both MPSC and CPU_GENERIC?
>

No. The left-hand clause (X86_64 || !X86_GENERIC) indicates when using
these NOPs are *permitted*; the right-hand clause indicates when doing
so is *desirable*. The latter isn't, for example, for K8, even on 64 bits.

-hpa