[PATCH v3] watchdog: Add hook for kicking in kdump path

Don Zickus dzickus at redhat.com
Thu Apr 18 13:44:32 EDT 2013

On Thu, Apr 18, 2013 at 09:35:05AM -0700, Eric W. Biederman wrote:
> Don Zickus <dzickus at redhat.com> writes:
> > A common problem with kdump is that during the boot up of the
> > second kernel, the hardware watchdog times out and reboots the
> > machine before a vmcore can be captured.
> >
> > Instead of tellling customers to disable their hardware watchdog
> > timers, I hacked up a hook to put in the kdump path that provides
> > one last kick before jumping into the second kernel.
> Having thought about this a little more this patch is actively wrong.
> The problem is you can easily be petting the watchdog in violation of
> whatever policy is normally in place.  Which means that this extra
> petting can result in a system that is unavailable for an unacceptably
> long period of time.

Not really, just an extra period which isn't that much.  This would only
be noticable if kdump is setup and enabled and then _hung_, otherwise it
just quickly reboots and noone notices. :-)

> I expect most watchdog policies are not that strict, but this patch
> would preclude using those that are.

I would assume most of those users would not enable kdump and would not be

> And like is being discussed in another subthread it does look like
> changing the timeout and the interval should be enough all on it's own.

Probably and I will pursue that.  Thanks for the suggestion.


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