Re: [9fans] PowerPC Booting

[Geoff Collyer <geoff@collyer.net>]

I'm not claiming that it's impossibly hard to port Plan 9 to the Mac
(and I'd be happy to have it running on more common systems, not just
PCs and bitsys), just that it will take some work.

I'd start by looking at a current Darwin release, though I have found
that it takes a while to distill BSD and Linux code, especially
drivers, to their essentials, since they tend to be excessively
complex.  As a recent example, 3ware's Linux driver for their IDE RAID
controller is a 4,174 lines long (3,155 NCSL).  That's over 74 pages,
printed with pr; it's a short book.  This is insane!  It's just a
bloody controller (and the hardware is supposed to be doing most of
the work, as it should).  The entire Unix V6 kernel was only 11,600
lines.  Admittedly, the OpenBSD 3ware driver is just 1,550 lines, but
that's still too big.  It's also true that hardware is even more of a
pain in the ass than it used to be, but over 4,000 lines to drive a
disk controller is just bloat.

As you've alluded, there's also a difference between having Plan 9
running on a particular Mac and having it running on all (or even just
New World) Macs.  For instance, for newer Macs, you'll need USB, USB
keyboard and, for terminals, USB mouse support, unless you can get by
with using the OpenFirmware routines.  I also don't know if the
existing Power PC ports of Plan 9 are prepared to cope with multiple
processors, which isn't fatal, but it would be good to exploit a
second processor on machines that have them.