Watchdog timer expired, but panic logs not seen

Kaustubh Ashtekar ksashtekar at
Tue Sep 13 00:55:36 EDT 2011

On Fri, Sep 9, 2011 at 5:51 PM, sandeep kumar <coolsandyforyou at>wrote:

> Hi all,
> I wanted to manipulate the watchdog timer driver to see how it works in
> deadlocks.

> <snip>

> My question is this,
> When watch dog timer expires(hardware watchdog), its interrupt directly
> resets the system
> (or) it is treated as an interrupt and a handler is executed.

AFAIK, after the watchdog is triggered, the SoC/processor is completely
reset including all the peripherals. The main purpose of a watchdog is to
reset a processor which has locked up somewhere in some thread (with
interrupts disabled, maybe), effectively starving the thread which is
supposed to reset the watchdog periodically. Hence, there is no point in
having an interrupt handler to service watchdog interrupt.

But maybe some processors may have an option to have an periodic interrupt
from watchdog timer, whose only purpose is to reset the watchdog timer. If
this interrupt is not serviced for long time then the watchdog would reset
the system directly in hardware.

> THanks,
> Sandeep.
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