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

[Andi Kleen <ak@suse.de>]

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. 
> http://bugzilla.kernel.org/show_bug.cgi?id=4359)

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.

-Andi