I seem to be having some difficulty installing NetBSD 1.3 on this
Sun 4/280. The setup is two NEC 2363 SMD disks on a Xylogics xd 
controller. Currently xd0 has a working SunOS system on it and I'd
like to try NetBSD on xd1. 

Firstly, are there restrictions on where you're allowed to put 
partitions? If you define partitions (using sunos format) with a
starting at cyl 0 and then dd the miniroot into it, the PROM refuses
to boot that partition. Also, I seem to have managed to trash the
drive's defect map at some point [is this as serious as it sounds?]

As I understand it you're supposed to dd the miniroot into partition
b (swap). So I defined some plausible looking partitions (a = root,
b = swap, g = /usr, c = whole disk) for xd1 and dd'd the miniroot into
/dev/xd1b. If you then reboot and tell the PROM to boot xd(0,1,1)
it successfully loads the kernel. However, the kernel then decides that
its root fs should be on /dev/xd1a and falls over because it can't find
init... Isn't the miniroot supposed to be self contained? 

If you dd the miniroot into /dev/xd1a then it boots correctly but
then the install process runs newfs on /dev/xd1a which trashes the 
miniroot before install has finished using it :-<

Is there a way to tell the kernel to use a given device as the root disk?
This would presumably be the Right Way to solve the problem.
My other plan of attack is to define partitions in SunOS such that xd1a
is the right size for the swap partition, boot the miniroot from it,
and then redefine the disklabel in install to swap xd1a and xd1b. Would
this work?

While I'm here, two quick queries. I also have a CDC Sabre SMD drive,
but I can't work out how to configure it to be SMD disk 1 so it's not
a lot of use [the DIP switches labelled 'disk ID' seem to have no effect].
Anybody know how to do this?
Finally, I have a half inch magtape drive on a Xylogics xt interface.
It's not on the 'supported hardware' list; is anybody working on
support for it at all? 

thanks,
Peter Maydell