> Without TURBO040, this kernel works well.  With it, I cannot arrived at
> "login".
> [...]
> Enter pathname of shell or RETURN for sh:
> 
> Even though I could reached at that point and type "RETURN", the kernel
> stopped.

Good!  Everything looks correct up to here.  So the kernel is not
responding to the keyboard, right?

> Panic switch: PC is 0x8e6b6.
> Stopped at       _Debugger+0x6:  unlk    a6
> db>

And you cannot type at this prompt, right?
I'm not sure what to suggest at this point.  I plan to look into the
assertion that there is something wrong with the 040 bus/address error
handling.  If that is indeed the case, then it's probably the cause of
the error you get trying to load multi-user mode.  I will not be able
to look into that for another 12 hours or so.

-allen

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