Watchdog timer expired, but panic logs not seen

Mulyadi Santosa mulyadi.santosa at
Tue Sep 13 17:22:04 EDT 2011


On Tue, Sep 13, 2011 at 11:55, Kaustubh Ashtekar <ksashtekar at> wrote:
> 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.

Just to add, AFAIK watchdog is used in "locked" scenario because it
can't be masked and disabled...and it receives highest priority in
trap/interrupt by the processors.

AFAIK too, in most scenarios, handler is placed to picked up watchdog
signal...and it is this handler which is then fix the situation.

Only my 2 cents idea...


Mulyadi Santosa
Freelance Linux trainer and consultant


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