changes to SCSI drivers from 3.4 to 4.0

[Mike Caplinger]

I have a driver for a SCSI CDROM device that worked correctly under 3.4.
When I tried to recompile it under 4.0, it failed to compile because the
SCSI device unit block, struct scsi_unit in scsi.h, no longer has an
element struct  buf un_utab, which is described in a comment as "queue of
requests".  There have been a number of changes to the SCSI stuff, and I
was able to figure most of them out by reading include files, but nowhere
can I find a reference to the SCSI request queue.

Messing with the SCSI stuff has always been difficult, because Sun's "open
systems" policy apparently doesn't extend to the addition of new SCSI
devices -- there's no documentation I can find about the structure of how
SCSI devices work.  Note that the CDROM is not being treated as a block
device (only raw access is supported), but I still don't know enough about
the SCSI driver system internals to do the job.

Any help would be appreciated.  The only thing I need to know is where to
enqueue a SCSI I/O request for the generic SCSI driver code to find.

	thanks,
	Mike Caplinger, Ground Data Systems Scientist
	ASU/Caltech Mars Observer Camera Project
	mc at moc.jpl.nasa.gov