I'm not fully sure about logical vs. virtual addressing in Linux under
PowerPC (AMCC 440GX to be precise). From what I've read, it seems like
the PowerPC implementation of Linux should not need a HIGH MEMORY
distinction and thus all kernel addresses will be logical address. This
means, also, that they all have mappings too. Am I right about this?

Also, when it comes to block device drivers that use DMA, how much
low-level work must the driver do? Am I done after calling
blk_rq_map_sg() or do I need to tickle the 440GX's DMA hardware myself?

- Mark