> short, xdm was causing 'shared memory corrupt' errors in my correctly 
> configured ed0 driver by reading from the card's shared memory 
> through /dev/mem.

Why was xdm reading /dev/mem in the first place?

Memory reads can affect some hardware.  Usually through auto-incrementing
registers (two successive reads return data from two successive memory
locations) or by clearing interrupts or something like that.  Isn't 'ed'
the driver that had a lot of problems with some destructive probes?

-allen

-- 
Allen Briggs - end killing - allen.briggs@bev.net ** MacBSD == NetBSD/mac68k **
   Where does all my time go?  <a href="http://www.netbsd.org/">Guess.</a>