ISA physical I/O support

Hello, folks.

I've been playing with something which has festered a long time--support for
ISA DMA on systems with > 16M of memory. Right now the kernel quietly
ignores memory above the ISA limit, but this drove me crazy with my 64M PC.
So I've just gotten wired memory hooks set up so the bounce buffer support
of the floppy driver now correctly can get a low (< 16M) memory page and
handle requests from buffers in the upper 48M. page_wire() now takes a
third parameter, which is flags which can be defined on a per-architecture
basis. On PC/ISA, one flag is for WIRE_16M, and the PC-dependent VM will
try to go grab a suitable page and make it replace any existing page.

I need to do some more testing, and then apply similar changes to the SCSI
support. It's kind of fun to be hacking VSTa again, after a year or so of
being CPU bound on Cisco development. :-)

                                                Andy Valencia
Received on Sat Oct 24 14:52:13 1998