Re: [PATCH 4/4] MIPS: Avoid DIVU in `__div64_32' is result would be zero

From: Maciej W. Rozycki
Date: Tue Apr 27 2021 - 08:16:53 EST


On Thu, 22 Apr 2021, Maciej W. Rozycki wrote:

> NB, I have benchmarked the update with my DECstation, however my Malta
> has not come up after a reboot last evening and neither it has after a few
> remote power cycles. I have planned a visit in my lab next week anyway,
> so I'll see what has happened there; hopefully I'm able to bring the board
> back to life as I find it valuable for my purposes. I had to replace the
> PSU it came with already a couple years back and the new one is supposedly
> high-quality, so I fear it's the board itself.

For the record I have put the Malta back in service now.

It was weird: the YAMON status shown on the ASCII display was "E:P_UNKN",
i.e. "Unknown PCI device on board (should never happen)" (according to the
manual). Indeed I never saw that message before. By elimination I have
tracked down the DEFPA FDDI network interface to be the culprit and upon a
close inspection found a bent pin with the PFI ASIC (the PCI interface
chip), a 160-pin 20-mil PQFP part. It was IDSEL shorting to RST_L, the
adjacent pin. No wonder the card wreaked havoc with the system. Fixed by
carefully moving the pins apart with a razor blade (always good to have
one at hand!).

Now I wonder how this card happened to work with the pin bent for some
15 years and only finally developed a short now. Weird indeed, and
weirder even to see a second failure related to IC pins this year only.

Maciej