> the sunos boot blocks stop some feature
> from working (i think symbol table stuff.. pk?),

You need to use the NetBSD/sparc bootblocks in sparc/stand. They load
the symbol table into kernel memory. The SunOS boot blocks do not load
the symbol table.  Some stuff was broken, and just got fixed a few
hours ago.

> and the
> total lack of anything but a copyright in
> sys/arch/sparc/sparc/db_disasm.c stops you disassembling
> anything on the fly.

Someone should write a sparc disassembler. It should be rather easy.
(Chris Hopps wrote the m68k ddb disassembler in a few days. The figure
of 4 pizzas and numerous packages of smokes comes to mind.  The sparc
is a lot simpler.)