Folks...

I finally had the correct combination of "time" and "motivation" to
hack on the SGMAP DMA code a little, and get it working more the way
I'd like.

Why do you care?

Well, for those of you who have more memory than the direct-mapped DMA
window can address (this is usually ">1G" or ">2G"), then you can now
use all that memory.  It previously didn't work properly because I had
not yet implemented mbuf support in the SGMAP routines.

That is now fixed, and the routines are a bit more efficient -- I've
tested it by using all SGMAPs for all DMA on my AlphaServer 1200.

There is another optimization I plan on making, but it's not that
important right now.

I will be building a binary snapshot shortly that includes these
improvements.

-- 
        -- Jason R. Thorpe <thorpej@zembu.com>