I am getting:

ok boot -a
Boot device: /iommu/sbus/espdma@f,400000/esp@f,800000/sd@1,0   File and args: -a
>> NetBSD/sparc Secondary Boot, Revision 1.7
>> (christos@sparx.nyc.deshaw.com, Mon Sep 29 19:01:34 EDT 1997)
device[/iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/sd@1,0:a]: /iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/sd@1,0:d
boot: netbsd
Booting netbsd @ 0x4000
1351680+114424+73016+[76008+88879]=0x1a404f
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

data fault: pc=0xf000a1c0 addr=0xf01d6ff8 sfsr=3a7<FAV,OW>
panic: kernel fault
halted

Program terminated

With an older kernel, it works fine: 

This works on both:
	NetBSD 1.2G (GENERIC) #1: Wed Sep 17 16:32:38 EDT 1997

This does not on the 4m, but does on a 4c.
	NetBSD 1.2G (GENERIC) #6: Mon Sep 29 18:25:39 EDT 1997

christos