Hi folks, just thought I'd share.

After about a week of cpu time compiling kernals with various combinations
of options, I determined the following tidbit (which wasn't at all obvious
to me):

Even though you don't plan on using the serial ports on your 400 series
machine, you cannot comment out the following line:
apci*           at frodo? offset ?      # tty flavor

If you do, then the machine will hang after finding the scsi bus.

That was only part of the problem, the easy part.  I have two 400s
machines.  Machine A has no problems booting.  Machine B wouldn't boot when
I tried using any kernal I compiled (including GENERIC), up to and
including NetBSD 1.3.1.  Putting motherboard B in chassis A boots fine.  I
don't know if motherboard A in chassis B works, since I upgraded it to a
425 during the swap (it now boots any kernal I compile for it).

So, I've worked around the problem, but it still remains.  I don't know why
board B doesn't work in chassis B.  The only difference in the cases are
that:
A has two DIO-II slots and two RO3000T drives (has empty space where ISA(?)
  slots should be)
B has five DIO-II slots and three 2213A drives

Here's what got spat out when machine B crashes.

NetBSD 1.3.1 (FATMAC) #0: Sun May 10 15:42:46 EDT 1998
    mw@xarph:/mnt/fatmac/usr/src/sys/arch/hp300/compile/FATMAC
HP 9000/400 (50MHz MC68030 CPU+MMU, 50MHz MC68882 FPU, 32K physical-address
cach
e)
cpu: delay divisor 40, mmuid 7
real mem  = 67096576
avail mem = 56770560
using 1638 buffers containing 6709248 bytes of memory
Parity detection enabled
trap: bad kernel read access at 0x3
trap type 8, code = 0x4020755, v = 0x3
kernel program counter = 0x9348a
pid = 0, pc = 0009348A, ps = 2100, sfc = 1, dfc = 1
Registers:
             0        1        2        3        4        5        6        7
dreg: 00002704 0000000C 00000224 00000001 00000002 00000000 000A6000 00000002
areg: 00000000 000ADD84 000D1F78 000D1F74 FC0C9000 FC002000 000D1F2C FFEFFFFC

Kernel stack (000D1E3C):
0D1E3C: 00099ECC 000D1E8C 00000080 00000224 00000001 00000002 00000000 000A6000
0D1E5C: 00000002 000D1F78 000D1F74 FC0C9000 FC002000 00000000 00000000 000D1F2C
0D1E7C: 000018DE 00000008 04020755 00000003 00002704 0000000C 00000224 00000001
0D1E9C: 00000002 00000000 000A6000 00000002 00000000 000ADD84 000D1F78 000D1F74
0D1EBC: FC0C9000 FC002000 000D1F2C FFEFFFFC 00000000 21000009 348AB008 1EE80755
0D1EDC: 10280001 00000003 00000003 000D1F50 12280003 00093492 00093490 0009348E
0D1EFC: 00000000 0003FF0D 000FF487 00000000 00000000 FFFFC0C0 FFFF0000 20200000
0D1F1C: 00000003 00000000 00000019 000021C6 000D1F50 00001C1A 00002704 0000000C
0D1F3C: 00553040 000B74A0 20000000 21C60064 00094594 000D1F7C 00096090 0000000C
0D1F5C: FFF0C02C FC002000 000C7000 A0500004 FFEFFFFC 000BEB80 08E60000 005D4000
0D1F7C: 000D1FAC 00007BC4 000A73E4 0000000C FFF0C02C FC002000 FFEFFFFC FC0037EA
0D1F9C: 000D6000 00000000 00000000 FC002000 FFFFEF00 A0500004 00000002 FFEFFFFC
0D1FBC: FC0037EA FC0C9000 FC002000 00000001 00000000 00001000 FFEFFFFC FC0037EA
0D1FDC: 000D1FF4 00095CA4 000D6000 00001000 0000000C 00000000 00000000 00000000
0D1FFC: 00000000
panic: MMU fault
System halted.  Hit any key to reboot.

Good luck to anyone else that encounters this problem.

  -- MW