Chapter 27. Watchdog Resets
Sometimes a system will die with a “watchdog reset” message on the console and will drop into the boot PROM (or possibly reboot automatically). It’s not a panic: The system is no longer in control, it’s not dumping memory to disk, and the CPU has done a reset.
What is a watchdog?
Watchdog resets usually indicate a software problem, although the root cause may be hardware related. The immediate cause is a trap, like a page fault, that occurs in the middle of handling another trap. The kernel processes a trap with the Enable Traps bit in the Processor Status Register reset (turned off), which prevents the CPU from accepting another trap until the initial processing of the first one is complete. This means that another trap ...
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