Re: P6 NOPs again: MPSC?

From: H. Peter Anvin
Date: Mon Mar 10 2008 - 16:28:14 EST


Hugh Dickins wrote:
I've now noticed that the machine I call MPENTIUM4 for 32-bit kernels
is called MPSC for 64-bit kernels, and in that case it still doesn't
get the P6 NOPs which I'm guessing it ought to (yeah, I'm so excited
about the speedup I can expect from P6 NOPs, can we perhaps have a
little silvery "Using Genuine P6 NOPs" sticker to put on the box? ;)

I'm suspecting that the patch below is actually wrong, and that it's
really the "(X86_64 || !X86_GENERIC) &&" which should be changed;
but very unsure of my ground and what's right for CPU_GENERIC -
the 32/64 heritage of x86/Kconfig.cpu rather confuses me.

Over to you to do the right thing, I'm hoping, please, Peter!


X86_64 && !X86_GENERIC comes from not wanting to be a compatibility issue when compiling for generic CPUs. There are some 32-bit otherwise i686-compatible chips (from VIA and Transmeta) which don't have these NOPs.

-hpa

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