You wrote (in your message from Sat 17)
 > > 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?
 > 
xdm is chesuming the first 16M of /dev/mem to get a less predictable
random number generator than the ones in libc, to generate keys for
the XDM-AUTHORIZATION-1 autenthification protocol. (see
xc/programs/xdm/genauth.c for details).

It does this only if you have WrapHelp.c and build xdm with HasXdmAuth
defined in your site.def file. In this case, you can add a #define
FRAGILE_DEV_MEM in dm.h to skip the first megabyte of memory.

Another workaround is to give the resource DisplayManager.randomFile
a nonexisting file. xdm will then revert to a more classical random
number generator.

XDM-AUTHORIZATION-1 is not compiled in the standard XFree86 binary
distribution since I don't have the right to have WrapHelp.c on my
discs here in France. 


					Matthieu