Chris,

I've just tested the boot.ip28 test on an Indigo 2 Impact R10K
machine.  It looks like it loaded, but bailed quickly.

I apologise for not having all the output... I don't have a serial
console on that machine yet.  It is a page full of register hex
dumps--way too much to transcribe to paper.  But here's the first 
few lines--I'll work on getting a serial console to the machine
to capture verbatim output.

>boot -f bootp():/tftpboot/boot.ip28
Obtaining /tftpboot/boot.ip28 from server mod1.mrynet.com
44976
Exception: <vector=Normal>
Status register: 0x34004883<CU1,CU0,FR,IM7,IM4,IPL=???,KX,MODE=KERNEL>
Cause register: 0x801c<CE=0,IP8,EXC=DBE>

(And a page full of more hex output.)

-scott