NOTICE: major changes to ofppc incoming

[Tim Rightnour <root%garbled.net@localhost>]

A complete rewrite of the ofppc port has been committed to the
ppcoea-rennovation branch as of yesterday.  This rewrite will significantly
change how the port works in general, and there are some caveats that go with
this. Rationale for the change is at the bottom of this email.

1) The port is now more like other ppc ports, where we interface with the
hardware directly, rather than performing all IO/etc through the OFW builtin
drivers.  The OFW is now used to locate and setup devices, which we talk to via
the standard MI devices in NetBSD.

2) The port probably does not run on any machines as of today.  I believe that
it will be relatively straightforward to fix up the port to run on a number of
different machines that have been port targets for ofppc.  The amount of work
required to get the port running on those machines should now be much much less
than it would have been before.

I believe the IBM 7043-150 or 7046-B50 would be the easiest target to get the
new ofppc running on.  At a minimum, I suspect there would need to be some
fiddling with the console, bus_space, and isa code to get it to single user.

Other machines, like the pegasos, or efika, will be slightly more difficult,
but I feel that is primarily due to the interrupt controllers on those devices.

If anyone decides they would like to take a crack at porting ofppc to a
machine, and needs assistance understanding some of the code, I will be more
than glad to assist as much as I can.

Rationale for this change:

1) Accessing all hardware via OFW drivers was slow, and completely dependant on
the firmware being 100% compliant with the spec.  It seems to have turned out
that this is a rather rare occurance.

2) A large target "market" for ofppc is the IBM RS6000 series of machines that
run OFW (the black machines).

3) The amount of work required to rewrite ofppc in this manner was significant,
and it is believed that the initial hurdle of this rewrite is what was holding
back further development on the ofppc port.  Getting ofppc running on a machine
should now be a much more achievable goal for someone.

---
Tim Rightnour <root%garbled.net@localhost>
NetBSD: Free multi-architecture OS http://www.netbsd.org/
Genecys: Open Source 3D MMORPG: http://www.genecys.org/