cpu error 4 on R12000 O2

Hi,

I've been giving 5.1 a try on a couple of O2 systems. I did the install
on a R5000/180 O2 and that went smoothly, X11 works on the console and
I've successfully compiled a few packages from pkgsrc.

Next I moved the disk into my R12000/270 O2, it boots up OK, X11 works,
I can login and run some commands but after a short time I get error
messages like this:
crime: cpu error 4 at address 74518336
crime: cpu error 4 at address 68283400

After a few of these, with different addresses, the system hangs, no
response to the keyboard or to ping. A hard reset is needed to
reboot it. Now, I seem to remember a thread a while back about the
problems associated with R10000/R12000 CPUs so I'm just wondering
what is the current state of R12000 support? Should it work or is it
still known to be temperamental?

FYI, kernel is GENERIC32_IP3x.

George