powerpc: use mm zones more sensibly

[Michael Ellerman]

On Sun, 2018-12-16 at 16:53:49 UTC, Christoph Hellwig wrote:
> Powerpc has somewhat odd usage where ZONE_DMA is used for all memory on
> common 64-bit configfs, and ZONE_DMA32 is used for 31-bit schemes.
> 
> Move to a scheme closer to what other architectures use (and I dare to
> say the intent of the system):
> 
>  - ZONE_DMA: optionally for memory < 31-bit (64-bit embedded only)
>  - ZONE_NORMAL: everything addressable by the kernel
>  - ZONE_HIGHMEM: memory > 32-bit for 32-bit kernels
> 
> Also provide information on how ZONE_DMA is used by defining
> ARCH_ZONE_DMA_BITS.
> 
> Contains various fixes from Benjamin Herrenschmidt.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/25078dc1f74be16b858e914f52cc8f

cheers