4.2 disk driver bug (and fix!)

[Ed Gould]

> There is a bug in the 4.2 disk driver: bad sector forwarding
> does not work for EAGLEs with System Industries controller.
> Problem is that the SI controller clobbers the MBA registers -
> one must use the drive registers `hpdc' and `hpda' to find
> where the BSE error has occurred.

The problem is in the SI controller, not the driver.  Various of us
have been complaining to SI for *years* to get their controllers to
emulate the DEC controllers correctly.
 
> A fix is available - all changes are in vaxmba/hp.c

A workaround, perhaps.  The fix would need to be in the controller
itself.  SI has a driver that they'll supply.  It has code in it
that comes from Berkeley, from me, from Si Field, and others to
deal with their controller.  Their driver is about 70% different,
on a line-by line basis (counting lines with differences), than
the 4.2 driver.  I doubt that it will correctly work with either
DEC or Emulex controllers so for some of us, it's not an option.

> gene cristofor
> vax135!gc

-- 
Ed Gould		    mt Xinu, 739 Allston Way, Berkeley, CA  94710  USA
{ucbvax,decvax}!mtxinu!ed   +1 415 644 0146