From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756697Ab3DRNAz (ORCPT ); Thu, 18 Apr 2013 09:00:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53992 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755056Ab3DRNAy (ORCPT ); Thu, 18 Apr 2013 09:00:54 -0400 Date: Thu, 18 Apr 2013 09:00:09 -0400 From: Don Zickus To: "Eric W. Biederman" Cc: linux-watchdog@vger.kernel.org, kexec@lists.infradead.org, wim@iguana.be, LKML , vgoyal@redhat.com, dyoung@redhat.com, linux@roeck-us.net Subject: Re: [PATCH v3] watchdog: Add hook for kicking in kdump path Message-ID: <20130418130009.GH79013@redhat.com> References: <1366233596-34681-1-git-send-email-dzickus@redhat.com> <87li8gaku0.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87li8gaku0.fsf@xmission.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 17, 2013 at 02:49:59PM -0700, Eric W. Biederman wrote: > Don Zickus 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