Repeatable panic at boot with ida(4)

[William Carrel]

With 5.1-RELEASE and all recent SNAP's a Compaq Proliant 1850R I have 
here will panic during boot.  The symptoms are consistent with the 
report mailed in by Ventsislav Velkov <veno at evrocom.net> on March 31st 
about other Compaq hardware, so it is within the realm of imagination 
that the machine has been broken for FreeBSD since at least then and 
that this impacts a variety of hardware.

On a verbose boot of the SNAP ISO we see:
...
Timecounters tick every 10.0000 msec
lo0: bpf attached
[0] f:00 typ:0 s(CHS):0/0/0 e(CHS):0/0/0 s:0 I:0
[1] f:00 typ:0 s(CHS):0/0/0 e(CHS):0/0/0 s:0 I:0
[2] f:00 typ:0 s(CHS):0/0/0 e(CHS):0/0/0 s:0 I:0
[3] f:80 typ:165 s(CHS):0/0/1 e(CHS):1023/254/63 s:0 I:50000
GEOM: Configure md0a, start 0 length 4423680 end 4423679
GEOM: Configure md0c, start 0 length 4423680 end 4423679
GEOM: new disk idad0


Fatal trap 12: page fault while in kernel mode
...
supervisor read, page not present
...
pid is 4 (g_down)
...
Stopped at:  ida_construct_qcb+0xca: movzbl 0x5c(%eax),%eax
db> trace
ida_construct_qcb...
ida_submit_buf...
idad_strategy...
g_disk_start...
g_io_schedule_down...
g_down_procbody...
fork_exit...
fork_trampoline...
--- trap 0x1, eip = 0, esp = 0xd6991d7c, ebp = 0 ---

It looks like this is coming from around line 396 in 
/usr/src/sys/dev/ida/ida.c where it bzero()s the hardware qcb...

Hopefully someone more familiar with this can give some pointers as to 
where I can help here.  The machine is empty so trial and error 
consists of burning ISOs/writing .flps and attempting boot with them.

Thanks
-- 
William Carrel