This section explains what happens when the system crashes and how you can analyze crash dumps.
When the system crashes voluntarily, it displays a message of the form
panic: why i gave up the ghost
on the console, takes a dump on a mass storage peripheral, and then invokes an automatic reboot procedure as described in reboot.8 Unless some unexpected inconsistency is encountered in the state of the file systems due to hardware or software failure, the system will then resume multiuser operations.
The system has a large number of internal consistency checks; if one of these fails, it will panic with a very short message indicating which one failed.
When the system crashes it writes (or at least attempts to write) an image of memory into the back end of the primary swap area. After the system is rebooted, you can run the program savecore.8 to preserve a copy of this core image and kernel namelist for later perusal. See savecore.8 for details.
To analyze a dump you should begin by running adb.1 with the -k flag on the core dump, as described in [a manual with the abbreviation DEBUG].
The most common cause of system failures is hardware failure, which can reflect itself in different ways.
See DIAGNOSTICS for some messages that you may encounter, with some hints as to causes. In each case there is a possibility that a hardware or software error produced the message in some unexpected way.
[a manual with the abbreviation DEBUG]
The favorite trap types in system crashes are ``Bus error'' or ``Address error'', indicating a wild reference. The process-id is the ID of the process running at the time of the fault, program-counter is the hexadecimal value of the program counter, status-register is the hexadecimal value of the status register, and context-number is the context that the process was running in. These problems tend to be easy to track down if they are kernel bugs since the processor stops cold, but random flakiness seems to cause this sometimes.
Created by unroff & hp-tools. © by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97