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

From: Guenter Roeck <linux@roeck-us.net>
To: Wim Van Sebroeck <wim@iguana.be>
Cc: Don Zickus <dzickus@redhat.com>,
	linux-watchdog@vger.kernel.org, kexec@lists.infradead.org,
	LKML <linux-kernel@vger.kernel.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	dyoung@redhat.com, vgoyal@redhat.com
Subject: Re: [PATCH v3] watchdog: Add hook for kicking in kdump path
Date: Mon, 27 May 2013 18:10:47 -0700	[thread overview]
Message-ID: <20130528011047.GA28597@roeck-us.net> (raw)
In-Reply-To: <20130527191618.GD14258@spo001.leaseweb.com>

On Mon, May 27, 2013 at 09:16:18PM +0200, Wim Van Sebroeck wrote:
>  Hi Guenter,
> 
> > > Hi Guenter,
> > > 
> > > Is there an easy way to determine which driver is loaded for each
> > > /dev/watchdogN device (from a script perspective).
> > > 
> > > Basically, I wanted to determine the module that needs to be included in
> > > the kdump initrd image.
> > > 
> > Sometimes. For example, the iTCO_wdt driver has an entry in /sys/devices, and
> > /sys/class/watchdog/watchdogX/device points to it. That is not always the case,
> > howewver. In my system, for example, the MEI watchdog is active, but there is
> > nothing I can find that would give me an indication that /dev/watchdog0 actually
> > points to the MEI watchdog driver.
> > 
> > Of course I might be missing something, and there might be some other means
> > to identify the driver from userspace. Would be great, actually, as I am having
> > the same problem.
> 
> Only when you set the .parent field in the watchdog_device data you will get the
> referal in the /sys/class/... tree. In iTCO_wdt.c you have the following code
> that does that: iTCO_wdt_watchdog_dev.parent = dev->dev.parent;
> 
> From the watchdog-kernel-api documentation:
> * parent: set this to the parent device (or NULL) before calling
>   watchdog_register_device.
> 
Hi Wim,

We live and learn ... thanks a lot for the hint!

Guenter

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