[PATCH 1/3] ARM: Add default SPARSEMEM settings

[Gregory Fong]

On Thu, Sep 11, 2014 at 7:22 PM, Kevin Cernekee <cernekee at gmail.com> wrote:
> We can still override these settings via mach/memory.h, but let's provide
> sensible defaults so that SPARSEMEM is available in the multiplatform
> kernels.
>
> Two platforms currently use SECTION_SIZE_BITS < 28, but are expected to
> work with 28 (albeit slightly less efficiently if not all banks are
> populated):
>
>  - mach-rpc: uses 26 bits.  Based on mach/hardware.h it looks like this
>    platform puts RAM at 0x1000_0000 - 0x1fff_ffff, and I/O below
>    0x1000_0000.
>
>  - mach-sa1100: uses 27 bits.  mach/memory.h indicates that RAM occupies
>    the entire range of 0xc000_0000 - 0xdfff_ffff.
>
> Several platforms need MAX_PHYSMEM_BITS >= 36 so we'll pick that as the
> minimum.  Anything higher and we'll fail the SECTIONS_WIDTH + NODES_WIDTH +
> ZONES_WIDTH test in <linux/mm.h>.
>
> Signed-off-by: Kevin Cernekee <cernekee at gmail.com>

Acked-by: Gregory Fong <gregory.0xf0 at gmail.com>