Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!cbosgd!ihnp4!zehntel!hplabs!hao!seismo!brl-tgr!tgr!bruce@godot.uucp From: bruce@godot.uucp Newsgroups: net.unix-wizards Subject: Re: What is this panic? Message-ID: <6565@brl-tgr.ARPA> Date: Sun, 9-Dec-84 16:28:53 EST Article-I.D.: brl-tgr.6565 Posted: Sun Dec 9 16:28:53 1984 Date-Received: Tue, 11-Dec-84 04:47:36 EST Sender: news@brl-tgr.ARPA Organization: Ballistic Research Lab Lines: 33 In article <13700084@uiucdcs.UUCP> irwin@uiucdcs.UUCP writes: >To quote, "The 750s have a problem with translation buffer parity errors >when running 4.2BSD, if the Rev 7 has not been installed. (tbuf panics) >These errors go away if the machine is brought to Rev 7. In addition to >this, 4.2BSD also has problems with cache memory parity errors, which >also cause panic type crashes. These will be fixed with Rev 8, which will >be available in the spring of '85. There are fixes in our software, both >VMS and our version of UNIX, which gets around the bug, but not in 4.2." He's being a little hard by half-blaming 4.2bsd for what is a DEC hardware bug. Pre rev 7 750s have a problem with tbuf par errors regardless of the software they are running. Some of the errors are recoverable and some are not; the proportion and frequency depend on the particular board set. VMS does go through more contortions trying to recover from it; the last I looked, it tries to recover, and if it can't, it terminates the running process if in user mode or crashes if in kernel mode. 4.2 panics when it can't immediately recover. My machine likes to take simultaneous tbuf parity, bus, and cache errors, which will also cause VMS to give up the ghost. I can't speak for rev 7; DEC has failed to show up twice this week to install it (but what's another few days, I was originally told to expect it in August). Actually, after going through 4 different L0003 modules, we finally have one which rarely gives the tbuf problem. There was also a bug in the original 4.2bsd tape in which a status word was masked incorrectly to determine whether it was a tbuf error, causing it to fail to try to recover on about half of the tbuf errors. -- --Bruce Nemnich, Thinking Machines Corporation, Cambridge, MA ihnp4!godot!bruce, bjn@mit-mc.arpa ... soon to be bruce@godot.arpa