As a preface, this is all with a 1.3 kernel.
  I've been having problems with this DS3100 dying with a ktlbmiss before
starting /etc/init so I did some poking today.  On my 2100 (which works) I
notice that, at this point, there are only two valid TLB entries--the ones for
the u-area, so I gather.  However, on the 3100 there are *many* entries marked
as valid.
  From looking at code in mach_init() from mips/mips/machdep.c, it would appear
that only the first two TLB entries are ever touched--the rest are left in
their default state.  Should the PROM monitor normally be invalidating all of
the entries?
  Anyway, I'm going to have at this code and see if that fixes my problem.  If
anyone has any advice in the meantime please let me know.

-- 
David Evans          (NeXTMail/MIME OK)             dfevans@bbcr.uwaterloo.ca
Computer/Synth Junkie                      http://bbcr.uwaterloo.ca/~dfevans/
University of Waterloo         "Default is the value selected by the composer
Ontario, Canada           overridden by your command." - Roland TR-707 Manual