I have been happily using a cross toolchain on NetBSD
for a couple of years for bringing up my HW designs
based on 68332, MPC860 and MPC850.

Currently I use insight-5.0 (gdb-5.0 with a ticklish GUI)
with somewhat extended Sergey Drazhnikov's patches for
MPC8xx BDM. More work needs to be done to improve
robustness, make it disassemble from target memory rather
than from the image in the host's memory and smooth many
other rough edges. With the correct incantations it is,
however, perfectly usable for bringing up new boards,
memory testing, programming flash and doing firmware
development.

At some point I've got the Coldfire going with gdb-4.16
with modified Gunter Magin's patches, but since I have
soon switched to an MPC860 project, I've stopped further
work on Coldfire BDM. The mods are probably still somewhere
on the backups.

CPU32 and Coldfire have fairly similar low level BDM
command format - they both use almost the same set of
17-bit commands, but are different at the higher level -
resetting, stepping and breaking.

MPC8xx BDM is completely different, MPC8xxx BDM is surely
even more esoteric. The only thing all four families
have in common is that each has a synchronous serial
debug/jtag port.

Nenad Crnko