PANIC! UNIX System Crash Dump Analysis Handbook (Bk/CD-ROM)

What do you do next ?

Once you have the boot PROM ok prompt, you can use some special PROM commands, shown below, to dump out information about the state of the system when it received the watchdog. This information includes the actual instruction that caused the problem and a stack trace of how it got there. Note that some of these commands start with a dot.

• .registers ” Displays many of the kernel internal CPU registers.

• .locals ” Dumps out the registers in the current register "window." These are the registers that were in use at the time of the crash.

• .psr ” Prints the Processor Status Register contents in a readable format.

• ctrace ” Displays the return stack (similar to a $c command in adb ).

• wd-dump (sun4d architectures only) ” Displays watchdog information on the console, including the PC value, which is the location of the instruction that caused the crash.

It would be best to run every one of these commands. They all have useful information that will help you decipher where and why the system reset itself.

Unfortunately, at this point the kernel is not running, so you can't save this information to a file. You'll have to copy the information down on paper for later reference and analysis.

An alternative console device

Transcribing data from the console screen to paper is not much fun. One way around this is to use another system as a console server and tip into one of the tty ports from a command-tool window. You can then run commands from the other system and save the output. It does mean, however, that you have to set up your crashing system ahead of time so that the console is on one of the tty ports.