HEADS UP: ATA bus dma code MFC'd

[Robert Watson]

On Fri, 5 Sep 2003, Mike Tancsa wrote:

>          A naive question, but what does the bus DMA code do in STABLE ?

busdma abstracts the management of buffer addresses for DMA to permit
drivers to operate across hardware architectures and addressing schemes
without modification.  This is required for some drivers to support PAE,
where the size of a hardware address is not the same as an address
pointer, which was an assumption present in several drivers previously. 
It's being used in -CURRENT to improve the portability of drivers to
64-bit architectures, but the primary benefit on -STABLE is making the
drivers work with PAE. 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Network Associates Laboratories