x86: set PAE PHYSICAL_MASK_SHIFT to 44 bits.

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When a 64-bit x86 processor runs in 32-bit PAE mode, a pte can
potentially have the same number of physical address bits as the
64-bit host ("Enhanced Legacy PAE Paging").  This means, in theory,
we could have up to 52 bits of physical address in a pte.

The 32-bit kernel uses a 32-bit unsigned long to represent a pfn.
This means that it can only represent physical addresses up to 32+12=44
bits wide.  Rather than widening pfns everywhere, just set 2^44 as the
Linux x86_32-PAE architectural limit for physical address size.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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Jeremy Fitzhardinge 2008-06-06 10:21:39 +01:00 • committed by Ingo Molnar

parent 668231141f

commit ce8e37cdbd

1 changed files with 2 additions and 1 deletions

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include/asm-x86/page_32.h

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