Re: [PATCH UPDATED] x86: set PAE PHYSICAL_MASK_SHIFT to 44 bits.

Ingo Molnar
2008-06-10T10:32:23Z

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> 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.

applied to tip/x86/cleanups - thanks Jeremy. No urgency for v2.6.26,
right?

Ingo