oops!  i forgot the "more in a bit" bit...  8-)

Re: device DMA into other devices' space:

	(1) if target device is on the same bus, then bus addresses
	    should be pretty easy.

	(2) if target device is on a different bus, then you need
	    to translate the address on one to the address on another.

The bus_dma* interfaces proposed here were intended for device<->memory
transfers, however.  I'm willing to say "cross the other bridge when
we come to it for real," since the possibility space is ... very large
and we need a real, practical solution to this problem Soon.



cgd