[9fans] Plan9 on QNAP TS-212 NAS (kw)

[Jared Jennings <jjenning@gmail.com>]

Hello everyone, I got a QNAP TS-212 filer, because it purports to have
the same processor as the SheevaPlug, but has space in its case for
two SATA hard drives, and a separate power supply, and a cooling fan,
thus neatly avoiding all the problems I foresaw in using a SheevaPlug
as a file server.

Anyway, upon booting 9plug according to the instructions in
booting(8), I got this sort of thing:

Marvell>> tftp 0x1000 kw-example
[...]
Marvell>> tftp 0x800000 9plug
[...]
Marvell>> go 0x800000
## Starting application at 0x00800000 ...

Plan 9 from Bell Labs

l1 D: 16384 bytes, 4 ways 128 sets 32 bytes/line; write-through only
l1 I: 16384 bytes, 4 ways 128 sets 32 bytes/line; write-back type `reg
7 ops, format C' (016) possible
l2 cache: 256K or 512K: 4 ways, 32-byte lines, write-back, sdram only
cpu0: 1200MHz ARM Marvell 88F6281 A1; arm926ej-s arch v5te rev 2.1 part 131
#l0: 88e1116: 100Mbps port 0xf1072000 irq 11: [mac address]
#l1: ether1116: init mii failure
#u/uspurious irqbridge interrupt: 00000010
spurious irqbridge interrupt: 00000010
spurious irqbridge interrupt: 00000010
spurious irqbridge interrupt: 00000010
spurious irqbridge interrupt: 00000010
[repeats for about 15 seconds at more than 100 messages per second,
then the system reboots]

Judging from the place where that message is printed, in
/sys/src/9/kw/trap.c (search for irq%s), the 'bridge' sort of
interrupt is flagged in the CPU status register; the documentation
from Marvell shows what each bit in the low and high interrupt
registers means, but that's not the sort of interrupt I'm getting
spuriously here.

I don't think it's far from working, but I don't know how to advance
from here. Any ideas?