linux-2.5.6 scsi DMA mapping and compilation fixes (not yet working)

[Adam J. Richter]

	Warning: these drivers do not work yet.

	ftp://ftp.yggdrasil.com/private/adam/scsi-linux-2.5.6-diff.gz

	This patch allows all of the SCSI drivers that are available on
x86 to build, except for these:
		o The NCR53c80-based drivers (according to Alan Cox, there
		  is a new driver in the 2.4.x tree, and I don't want to
		  add a port of that driver to this already huge patch).

		o 53c7,8xx - I believe we have other scsi drivers that
		  cover the same hardware, so I have skipped this driver.

		o dpt_i2o - I need to understand the i2o system a little more
		  to determine whether all of the similar looking code in
		  drivers/messages/i2o and dpt_i2o is redundant or necessary.

	The patch adds a little code to scsi.c to allow scsi drivers
to tell the mid-level code to automatically map and unmap gather/scatter
lists.  This has simplified the porting process immensely.

	The patch also adds a routine for using the SCSI request
scratchpad area for accessing scsi requests in memory (primarily
for non-DMA drivers).  This eliminated some code replicated in
a multiple scsi drivers and basically enabled me to the need to
add very many calls to kmap and kunmap in each driver.

	There are also a few patches that juat add PCI or ISAPnP
device ID's, so that the boards will work with automatic
module loading based on device ID's.

	I owe an email to Tim Sullivan who tried my BusLogic and found
that it paniced at initialization.  So, these drivers probably do not
work yet.  Nevertheless, I would be interested in people looking
at the patch or even trying it just to see how it fares on other
hardware.  All that I know is that the code compiles and has no undefined
symbols, except for scsi_reset_host in BusLogic.c (I guess you can
comment it out for now, which is I told Tim to try).

	I want to emphasize that this patch is just a snapshot of
work in progress at this point.  I just finished getting the drivers
to compile and link.  I am going to step away from this for a while,
perhaps until tomorrow, but I thought I should post this in case
anyone is interested.

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