G3 experiments

[Erik Bertelsen <erik%mediator.uni-c.dk@localhost>]

I'm playing a little with NetBSD on my Macintosh G3 Desktop machine.

I've retrieved the NetBSD/macppc root disk image from nandra and
installed it at the beginning of an external SCSI disk. This set-up
is bootable, but only usable with a serial console on the G3 --
this surprised me a little, as I could use OpenFirmware
with the ADB keyboard and Mac monitor to walk the device tree and to
boot Linux/PPC... but what the heck...

By bootable I mean that I see the boot messages and that the boot
stops when it cannot find a root device, i.e. at a deterministic place.

The G3 is apparently different from the other machines that has
been used with NetBSD/macppc, as the code currently expects the 
device tree to start with a Bandit PCI bridge with (one ? or) two
PCI busses, while on the G3, there is no Bandit. The root of the
device tree is /pci@80000000 with most of the rest of devices
attached to /pci/mac-io.

I've also installed MKLinux on another SCSI disk and later Linux/ppc
on top of that.

By installing binutils and egcs from /usr/src/gnu/dist on Linux as
a cross compiler for powerpc-apple-netbsd1.3E, and porting a few
other utilities to Linux (in particular /usr/sbin/config), I'm 
actually in a position to compile and install new NetBSD kernels
on the NetBSD disk by mounting it as an UFS file system under Linux.

I'm no expert on neither OF nor PCI busses, but with /pci in the
device tree being the PCI bus, I wonder whether the root of the
device tree represents a PCI bridge.

I'll continue my experiments with changing arch/macppc/pci/bandit.c
and see if I can get the PCI bus configured correctly.

I know that there is still a long way until I have a working 
NetBSD/macppc system on my G3, as neither the mesh scsi controller
nor the bmac ethernet controller seem to be supported yet.

Is there any opinion about whether a PCI ethernet card will be
a viable solution for an NFS based system ?

Any other advice or warnings about dead ends are welcome :-)

best regards
Erik Bertelsen