Nubus issue on LC II

[John Klos <john%ziaspace.com@localhost>]

This is an interesting one... I just got a Mac LC II motherboard which 
I've recapped so I could use it to test NetBSD. While a system with 10 MB 
of memory isn't going to be all that practical, it'll at least will let me 
have a system on which I can make sure m68030 stuff works.

Separately, it seems that sbc* with PDMA disabled is required for a 
SCSI2SD to work on this (and possibly other) m68030 Macs.

After compiling a kernel with lots of stuff removed, I booted and came 
across my first problem: ethernet didn't work. I could configure the card, 
but no bits flowed on the wire. This is an ae* card which I just bought, 
so instead I pulled a Sonic card from a working system, and got this:

...
nubus0 at mainbus0
sn0 at nubus0 slot a: Macintosh LC Ethernet Adapter
sn0: Ethernet address 00:01:98:34:0a:af
sn1 at nubus0 slot c: Macintosh LC Ethernet Adapter
sn1: Ethernet address 00:01:98:34:0a:af
sn2 at nubus0 slot e: Macintosh LC Ethernet Adapter
sn2: Ethernet address 00:01:98:34:0a:af
...

Trying to access sn0 causes the system to lock up. Trying to access sn1 
causes the system to lock up, but it's at least slightly responsive for a 
minute or so. Configuring sn2 gives me a working network connection.

Newer Tech Slot Info in System 7.6.1 shows the ethernet card in slot E and 
the other slots empty.

Can anyone venture any guesses about why the Nubus scan is problematic on 
this system? ae* scanned just fine.

Otherwise, I think it's very interesting that NetBSD 8 can still boot, 
albeit slowly and to a not very practical state, on a 16 MHz m68030 with 
10 megabytes of memory :)

John Klos