Back in (I think) October I posted a description of a problem with the
Sable's ethernet interface. (Periodically, and for no apparent reason,
inbound packets would get stuck. As soon as the system sent a packet
to some other machine, the inbound clog would clear.)
Through a combination of absentmindedness and overwork, I never did get
around to posting a summary. So better late than never, here it is ...
I got some really helpful replies from a couple of DEC folks (who shall
remain nameless to keep them from getting swamped with unsolicited mail).
The first reply I got said
| [...] I believe you're seeing a bug in the Tulip driver. One
| that was recently discovered, and that too quite by accident.
| (A line of code was deleted and did not get reinstated.)
|
| It has to do with the driver failing to reset a timer when the
| transmit ring transitions to an inactive state (0 entries pending).
|
| Each time a transmit packet is given to the device, a timer is
| reset to go off after 5 seconds. This timer therefore never goes
| off if the device is kept busy. If, however, a new transmit does
| not come in within 5 seconds of the last one, then the timer
| goes off and the interface is reset. I believe this reset is what
| causes things to get hung-up.
The bug apparently first appeared in V2.0b, but was discovered too late
for a fix to make it into V3.0. Anyway, the helpful DEC person sent me
a patched version of the TULIP driver, and the problems disappeared. He
also mentioned that he had arranged for the patches to be made available
through Digital's Customer Support Center (for folks covered by a support
contract, of course). The relevant patch numbers are
OSFV20-065 (for OSF/1 V2.0b)
and
OSFV30-40 (for OSF/1 V3.0)
Mark Bartelt 416/978-5619
Canadian Institute for mark_at_cita.toronto.edu
Theoretical Astrophysics mark_at_cita.utoronto.ca
"Clothes not busy being worn are busy drying." - Dylan, on laundry day
[ singing "It's all right, ma (I'm only bleaching)" ]
Received on Fri Feb 24 1995 - 10:24:57 NZDT