mps(4) driver (LSI 6Gb SAS) commited to stable/8

[Kenneth D. Merry]

I just merged the mps(4) driver to stable/8, for those of you with LSI 6Gb
SAS hardware.

It is only included in GENERIC on amd64, since that is the only
architecture that I know of that it has been tested on.  It may work on
i386, if anyone would like to try it out.

There are known endian issues, so testing on a big-endian platform (like
powerpc) won't work.  If you'd like to help fix the endian issues, let me
know.

Integrated RAID support is not included in this version of the driver, but
LSI has almost completed their version of the driver that does include IR
support.  That will hopefully be going into -current in the next few weeks.
There are lots of changes in their version of the driver, particularly in
the probe code.

There are also a couple of othere issues with the driver that I am planning
to fix in -current today and merge back into stable/8 in a few days.  In
particular I have fixes for these issues:

 - I/O locks up when you run out of S/G chain frames.
 - The device queue is not frozen on errors.
 - For some firmware revisions, the firmware will not return all
   outstanding commands for a device when the device goes away.  Cleanup
   logic is needed.

Let me know if you run into any issues.

Ken
-- 
Kenneth Merry
ken at FreeBSD.ORG