extend sysmon watchdog modes?

[Cliff Neighbors <cliff%netbsd.org@localhost>]

I am seeing a need for a new watchdog mode that is similar to
WDOG_MODE_KTICKLE but instead of the watchdog service function
running from a callout it needs to run from a (higher level)
hardware interrupt.

This mode would be useful for example when a system can 
legitimately spend significant time with callouts blocked, 
as when handling sustained heavy interrupt loads.

It would be especially useful on such systems when the only 
watchdog timeout behavior is system reset.

A simple way to provide such feature would be to add e.g.
WDOG_MODE_ITICKLE which if supported on a given system would 
allow the watchdog to be serviced from a machine-dependent 
hardware interrupt.

Ability to additionally specify what IPL use would be also nice
but perhaps not necessary.

Has anyone else run into a similar need?
Any thoughts on alternative solutions?

     -cliff-