powerpc/32: Allow __ioremap on RAM addresses for kdump kernel

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While for debugging it is good to catch bogus users of ioremap, though
for kdump support it is more convenient to use __ioremap for
copy_oldmem_page() (exactly as we do for PPC64 currently).

Note that copy_oldmem_page() calls __ioremap with flags set to '0',
so it should be safe with the regard to the caches.

The other option is to use kmap_atomic_pfn()[1], but it will not work
for kernels compiled without HIGHMEM.

That is, on a board with 256MB RAM and crashkernel=64M@32M case, the
!HIGHMEM capturing kernel maps 0-96M range, which does not include all
the memory needed to capture the dump. And, obviously, accessing
anything upper than 96M will cause faults.

[1] http://ozlabs.org/pipermail/linuxppc-dev/2007-November/046747.html

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

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Anton Vorontsov 2008-12-17 10:09:10 +00:00 • committed by Paul Mackerras

parent 6f29c3298b

commit 01695a9687

1 changed files with 2 additions and 0 deletions

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arch/powerpc/mm/pgtable_32.c

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