Date: Wed, 15 Jan 2014 11:55:12 -0500
From: Vivek Goyal <vgoyal@redhat.com>
To: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Dave Young <dyoung@redhat.com>, wim@iguana.be, dzickus@redhat.com,
        bhe@redhat.com, linux-watchdog@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] watchdog: add a parameter for stop wdt before register
Message-ID: <20140115165512.GD3180@redhat.com>
References: <20140114082323.GA4485@dhcp-16-126.nay.redhat.com>
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 <20140115005931.GB23767@dhcp-16-126.nay.redhat.com>
 <20140115121556.0407a099@alan.etchedpixels.co.uk>
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On Wed, Jan 15, 2014 at 12:15:56PM +0000, One Thousand Gnomes wrote:
> > watchdog and crash dump really conflicts to some degree, from the watchdog
> > point of view it can reboot system whhen kdump kernel hangs. But from kdump
> > point of view it want ensure saving the vmcore for later debugging.
> > 
> > Maybe we can only select only one in this case.
> 
> You want to be able to make a decision at runtime which to use.
> 
> > > - if it can be stopped, you can open and stop it
> > 
> > For the last one since crashing happens we have no chance to open and stop.
> 
> When you decide you need to set up to catch a core rather than just
> crash you can open and stop the watchdog (if supported), and you can then
> set up for a kdump and then at some point later if it crashes capture the
> dump.

Disabling watchdog if kdump serice starts will not make many happy. If
kernel hangs, we don't have a functionality to reboot it.

What about other idea of keeping watchdog interval long enough that new
kernel can boot, driver can load and then new driver/user space can
continue to kick the watchdog. And if second kernel hangs, watchdog will
reboot the system.

Thanks
Vivek
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