RE: [ECOS] Hardware Watchdog

[Gary Thomas <gthomas at redhat dot com>]

On 26-Jul-2001 Doug Fraser wrote:
> Interrupts may not be enabled in redboot, but
> does that stop him from installing his own
> tick handler and servicing the watchdog from there?
> The maximum time on the 860 watchdog is around
> three seconds with a 50Mhz CPU clock.
> As Christoph mentioned, the watchdog activates
> a hard reset cycle, and there is nothing you can
> do to catch it. The other problem is that if you
> disable the watchdog, you cannot reenable it
> without performing a hard reset.
> 

So the idea is that you need some piece of code telling
the watchdog "I'm alive", correct?  Surely this can be
done without all of the baggage of handling interrupts.

> As well as servicing it with a tick interrupt
> during redboot, you could also disable it if
> the redboot polling mechanism detects a GDB
> connect. You probably want the watchdog off
> during debugging anyway, so that would allow the
> target to boot with a watchdog in a normal run
> state, yet reduce the complexity of having to
> service it during a debug session.
> 

I don't see how you can handle interrupts without enabling then.
Once they are enabled, then other interrupt conditions might need
to be serviced, etc.

I think it much better/wiser to figure out where it might be "looping"
and put in stuff to tickle the watchdog appropriately.