memory with __get_free_pages and disabling caching

[Paul Mackerras]

Kallol Biswas writes:

> We have a little endian device on a PPC 440GX based system.
> The descriptors need to be swapped. With E bit turned on we can save
> swapping time.

Writing the descriptors with stwbrx should be just as fast as using
stw, and eliminates the need for a special mapping.

If you need it to be cache-inhibited, you should be using
dma_alloc_coherent() or pci_alloc_consistent().

Paul.