I've been looking at the trap.c file for the sh3 port and I was
wondering about some specific differences between the handling of the
sh3 vs. sh4 arch in the trap.c file.  I've yet to figure out why the
SH4_P1SEG_TO_P2SEG is needed for the sh4... I checked out the hardware
docs for both cpus and I didn't find much difference, at least after a
quick look, between the two MMUs.

Also, in some cases there is a check for vm != NULL which is only
applied to the sh4 cpu and not the sh3... I'm not sure what his is
about.

Thanks,
Tyrel