Panic! UNIX® System Crash Dump Analysis

Chapter 32. Hanging Instead of Swapping

Let’s examine a system hang. This is a SunOS 4.1.2 (Solaris 1.0.1) sun4c machine that was “not responding to the keyboard.” The user at the console, using the window system, had the system freeze up on him. It did respond to the L1-A sequence, so he killed it.

Initial information

To start, verify a few things. We can be sure this is a crash dump taken from a hang by looking at the panic message that was printed on the console: “panic: zero” means it was forced by someone via the keyboard (either with an L1-A sequence or a Break). We should also verify that it is a 4.1.2 release kernel.

zatch 11: strings vmunix.2|grep SunOS 
SunOS Release 4.1.2 (WRANGLER) #2: Thu Aug 20 18:52:38 CDT 1992 

zatch 12: adb -k vmunix.2 ...