watchdog: hw+sw?

[Andriy Gapon]

I have some vague thoughts on using SW_WATCHDOG and a hardware watchdog together.
I think this could be useful but I am not sure how to implement this.
The idea is this: timeout for SW_WATCHDOG is smaller than timeout for hw wd; when
some freeze happens sw wd logic kicks in first, stops hw wd and produces either
panic or ddb prompt; if the freeze is so severe that sw wd can't run (e.g.
hardware is messed up badly) then hw wd performs its duty.
I am mostly interested in having this in unattended mode where kernel dump could
be useful for later analysis but the system should recover in reasonable time.

Suggestions, opinions?

Thank you!

-- 
Andriy Gapon