Re: [discuss] [Patch 1/2] x86, x86_64: Intel HT, Multi core detection fixes

From: Andi Kleen
Date: Wed Oct 12 2005 - 16:50:18 EST

On Wednesday 12 October 2005 23:36, Siddha, Suresh B wrote:

> Fields obtained through cpuid vector 0x1(ebx[16:23]) and
> vector 0x4(eax[14:25], eax[26:31]) indicate the maximum values and might not
> always be the same as what is available and what OS sees. So make sure
> "siblings" and "cpu cores" values in /proc/cpuinfo reflect the values as seen
> by OS instead of what cpuid instruction says. This will also fix the buggy BIOS
> cases (for example where cpuid on a single core cpu says there are "2" siblings,
> even when HT is disabled in the BIOS.

I'm not too fond of this new booted_core variable. How about
you just put the true number of cores into x86_num_cores?
What should x86_num_cores be in your setup anyways if not
"booted cores"?

Also I must admit the number of different variables to keep
track of multicore and siblingness starts to become mindboggling,
so I would recommend you add a fat overview comment somewhere
that describes their definition and relationship. Or better put
something into Documentation, it is probably as confusing for
user space /proc/cpuinfo consumer too.

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