[PATCH v3 RESEND 14/17] ARM: LPAE: accomodate >32-bit addresses for page table base

Catalin Marinas catalin.marinas at arm.com
Mon Sep 24 11:17:26 EDT 2012

On Fri, Sep 21, 2012 at 04:56:12PM +0100, Cyril Chemparathy wrote:
> This patch redefines the early boot time use of the R4 register to steal a few
> low order bits (ARCH_PGD_SHIFT bits) on LPAE systems.  This allows for up to
> 38-bit physical addresses.

That's fine. We figured out that on the vexpress with A15 and sparsemem
enabled could only use 36-bit because of section number stored in the
top bits of page->flags.

An alternative to this patch could be to always patch in the upper
32-bit of phys_offset like you do in virt_to_phys(). We know that pgd is
always lowmem.


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