Re: unified percpu stuff

From: Jeremy Fitzhardinge
Date: Tue Jan 27 2009 - 12:51:18 EST

Brian Gerst wrote:
BTW, does the initial cpu0 percpu area get reallocated and moved during
boot, or does cpu0 keep using the same memory forever?

It is reallocated in setup_per_cpu_areas().

Hm, OK. What's the reason we need to move cpu 0's percpu area? Its always seemed a bit awkward.

Once it has been moved, how can I find the address of a variable in the original boot-time cpu 0 percpu area? There's a couple of pages which Xen will have marked RO which need to be made RW if they're being freed back into the kernel pool. Currently I use per_cpu_var(gdt_page), but guess that's a small offset rather than a directly usable address.

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