Re: [PATCH] percpu data: only iterate over possible CPUs

[Nathan Lynch]

Heiko Carstens wrote:
> > > Presumably not all architectures are doing that.
> > powerpc/ppc64, for instance, determines the number of possible cpus
> > from information exported by firmware (and I'm mystified as to why
> > other platforms don't do this).  So it's typical to have a kernel an a
> > pSeries partition with NR_CPUS=128, but cpu_possible_map = 0xff.
> 
> Simply because there is no such interface on s390. The only thing we know
> for sure is that if we are running under z/VM the user is free to
> configure up to 63 additional virtual cpus on the fly...

My "mystified" parenthetical was not meant as a criticism of
arch/!powerpc, but of the platform implementations themselves, for not
making such an interface available.
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