x86, mm: Add pointer about Xen mmu requirement for alloc_low_pages

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	279b706 x86,xen: introduce x86_init.mapping.pagetable_reserve

-v2: updated to commets from hpa to include commit name.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1353123563-3103-29-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
1 file changed