supposed to be Window 1, but a cut'n'paste error made it stomp over
Window 0, thus breaking ISA DMA. Fix this. (Confirmed to work with
floppy driver.)
While I'm here, do something I've been meaning to do for a while: change
Window 1 from a 1G at 2G to a 2G at 2G direct-mapped window, and add
a Window 2 of 1G at 1G SGMAP-mapped. Chain Window 2 to Window 1, and
use it as a fall-back for PCI DMA if the system has more than 2G of RAM.
member to the DMA tag, and calling the direct-mapped back-ends directly,
rather than through chipset-specific front-ends which pass the window
base as an additional argument.