linux-kernel - Re: [PATCH v3] watchdog: Add hook for kicking in kdump path

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Message-ID: <20130418130009.GH79013@redhat.com>
Date:	Thu, 18 Apr 2013 09:00:09 -0400
From:	Don Zickus <dzickus@...hat.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	linux-watchdog@...r.kernel.org, kexec@...ts.infradead.org,
	wim@...ana.be, LKML <linux-kernel@...r.kernel.org>,
	vgoyal@...hat.com, dyoung@...hat.com, linux@...ck-us.net
Subject: Re: [PATCH v3] watchdog: Add hook for kicking in kdump path

On Wed, Apr 17, 2013 at 02:49:59PM -0700, Eric W. Biederman wrote:
> Don Zickus <dzickus@...hat.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.
> >
> > The assumption is the watchdog timeout is at least 10-30 seconds
> > long, enough to get the second kernel to userspace to kick the watchdog
> > again, if needed.
> 
> Why not double the watchdog timeout? and/or pet the watchdog a little
> more frequently.

I am not sure if the watchdog timeouts can be doubled.  I think Guenter
was saying some have a max of a couple seconds?? Petting a little more
frequently might be an option.  Guenter can that be done with a softdog
option?

Cheers,
Don
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