After much effort, I just built a new -current kernel for my O2 natively.
NetBSD/sgimips seems to have several issues with my O2.  The first is that
clock interrupts doesn't seem to happen consistently.  My system constantly
loses time.  In fact, if I don't keep pinging the system constantly, the
system will eventually reset in watchdog timeout due to too much user time.
The other problem is while in 1.5A, the system usually could boot with the
ahc devices, in 1.5K the system just does a watchdog reset.

Setting $netaddr to 192.168.7.32 (from server fireball2)
memory 0x14e000 0xd50000
memory 0x1400000 0x8000000
Copyright (c) 1996, 1997, 1998, 1999, 2000
     The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
     The Regents of the University of California.  All rights reserved.

NetBSD 1.5K (GENERIC) #3: Thu Nov 23 22:32:28 PST 2000
     root@:/other/sgimips/kobj/GENERIC
128 MB memory, 110 MB free, 6848 KB for ARCS, 6656 KB in 1664 buffers
mainbus0 (root): SGI-IP32 [SGI, 6]
cpu0 at mainbus0: MIPS R5000 CPU (0x2321) Rev. 2.1 with MIPS R5010 FPC Rev. 1.0
cpu0: L1 cache: 32KB/32B instruction, 32KB/32B data, two way set associative
cpu0: L2 cache: 512KB/32B mixed, snooping
crime0 at mainbus0 addr 0x14000000: rev 1.1
mace0 at mainbus0 addr 0x1f000000
mace0: isa sts 0
mace0: isa msk 0
com0 at mace0 offset 0x390000 intr 4: ns16550a, working fifo
com0: console
com1 at mace0 offset 0x398000 intr 4: ns16550a, working fifo
pckbc0 at mace0 offset 0x320000 intr 5: stub
lpt0 at mace0 offset 0x380000 intr 4: stub
mec0 at mace0 offset 0x280000 intr 3: MAC-110 Ethernet, rev 1
mec0: station address 08:00:69:05:ad:d6
mec0: sorry, this is not a real driver
nsphy0 at mec0 phy 31: DP83840 10/100 media interface, rev. 1
nsphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
macepci0 at mace0 offset 0x80000 intr 7: rev 1
macepci0: ctrl ff0005ff
pci0 at macepci0 bus 0
pci0: i/o space, memory space enabled, rd/line, rd/mult, wr/inv ok
vendor 0x9004 product 0x8078 (SCSI mass storage) at pci0 dev 1 function 0 
not configured
vendor 0x9004 product 0x8078 (SCSI mass storage) at pci0 dev 2 function 0 
not configured
fxp0 at pci0 dev 3 function 0: Intel i82557 Ethernet, rev 5
fxp0: interrupting at mace
fxp0: detected 64 word EEPROM
fxp0: Ethernet address 00:90:27:37:a2:06, 10/100 Mb/s
inphy0 at fxp0 phy 1: i82555 10/100 media interface, rev. 0
inphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
biomask 7f netmask 7f ttymask 7f clockmask ff
boot device: <unknown>
root device: fxp0
dump device:
file system (default generic):
root on fxp0
mountroot: trying nfs...
nfs_boot: trying DHCP/BOOTP
nfs_boot: timeout...
nfs_boot: timeout...
nfs_boot: DHCP server: 192.168.7.3
nfs_boot: my_domain=local
nfs_boot: my_addr=192.168.7.32
nfs_boot: my_mask=255.255.255.0
root on fireball2:/clients/o2/root
root time: 0x3a1e0c88
root file system type: nfs
init: copying out flags `-s' 3
init: copying out path `/sbin/init' 11
Enter pathname of shell or RETURN for sh:
Terminal type is vt100.
We recommend creating a non-root account and using su(1) for root access.
#
--
Matt Thomas               Internet:   matt@3am-software.com
3am Software Foundry      WWW URL:    http://www.3am-software.com/bio/matt/
Cupertino, CA             Disclaimer: I avow all knowledge of this message