Subject: Re: Watchdog timer support
To: Jeff Smith <>
From: Jukka Marin <>
List: tech-kern
Date: 11/17/2000 08:43:13
On Thu, Nov 16, 2000 at 10:07:08PM -0800, Jeff Smith wrote:
> writes:
> > (Jason R Thorpe) writes:
> > > See the wdogctl(8) manual page for more information.
> > 
> > I've looked briefly at the manual page and the code, and, in at least
> > some ways, this interface seems Wrong.  What you "Really Want" in my
> > opinion is something more like:
> >
> >        * configure kernel to kick hw watchdog every (small amount of
> >          time).  (Fraction of a second, to multiple seconds if not
> >          running with next feature enabled.)
> >
> >        * optionally configure kernel to expect kick from userland
> >          every (larger amount of time).  (multiple seconds, or
> >          whatever you'd like.)
> This is very similar to what we have implemented in our watchdog
> code here at geocast.

I just implemented a system like this in our embedded system OS.  Any
number of processes can register themselves with the watchdog.  After
this, the processes are required to kick the dog regularly to keep the
kernel kicking the hw watchdog.  The processes may set their individual
watchdog timeouts if they like (to anything between 1 ms and 24 days).