Re: [PATCH] x86-64: fix 1:1 mapping init (hotplug case)

From: Ingo Molnar
Date: Fri Aug 22 2008 - 01:55:10 EST



* Jan Beulich <jbeulich@xxxxxxxxxx> wrote:

> While I don't have a hotplug capable system at hand, I think two issues need
> fixing:
> - pud_phys (in kernel_physical_ampping_init()) would remain uninitialized in
> the after_bootmem case
> - the locking done just around phys_pmd_{init,update}() would leave out pgd
> updates, and it was needlessly covering code portions that do allocations
> (perhaps using a more friendly gfp value in alloc_low_page() would then be
> possible)

applied to tip/x86/urgent. Some sort of memory hotplug simulation debug
code would be nice ... [bonus points for making it run automatically
during bootup, as part of the kernel init code]

it wouldnt even be all that expensive to test: we'd parts of RAM as
to-be-hotplugged, we'd boot in and then hot-add those ranges. It's not
full unrestricted RAM in the classic sense, but for most practical
purposes it would be that.

Ingo
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