> I have collected my idea...

Still I'm not sure what you exactly want to make.  I, and some in silence
supposedly, am afraid that you will make a bunch of fragmented files in
powerpc/ directory like as you did in other ports.  I'm very anxious the
revive of platid.c bozo.

1. it's a manageable practice to have a single plb.c or opb.c files with
#include files for supported processors, compared against having
myriad of xxx.c and xxx.h files which differs slightly and share common
in other file.

2. it's a matter of collaboration practice to have (to make efforts to have)
coherent set of program files for development aiming for the common goal.
It's the RULE of engineering of industrialized world.

3. it will not help releng pullup or portability for multiple targets to introduce
cpu_attach_args switch.

Toru Nishimura/ALKYL Technology