linux-kernel - Re: [PATCH v5 0/3] watchdog: allow setting deadline for opening /dev/watchdogN

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Message-ID: <20170522194448.GA29867@roeck-us.net>
Date:   Mon, 22 May 2017 12:44:48 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        linux-watchdog@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Sebastian Reichel <sebastian.reichel@...labora.co.uk>,
        esben.haabendal@...il.com
Subject: Re: [PATCH v5 0/3] watchdog: allow setting deadline for opening
 /dev/watchdogN

On Mon, May 22, 2017 at 07:07:51PM +0100, Alan Cox wrote:
> On Mon, 22 May 2017 16:06:36 +0200
> Rasmus Villemoes <rasmus.villemoes@...vas.dk> wrote:
> 
> > If a watchdog driver tells the framework that the device is running,
> > the framework takes care of feeding the watchdog until userspace opens
> > the device. If the userspace application which is supposed to do that
> > never comes up properly, the watchdog is fed indefinitely by the
> > kernel. This can be especially problematic for embedded devices.
> > 
> > These patches allow one to set a maximum time for which the kernel
> > will feed the watchdog, thus ensuring that either userspace has come
> > up, or the board gets reset. This allows fallback logic in the
> > bootloader to attempt some recovery (for example, if an automatic
> > update is in progress, it could roll back to the previous version).
> 
> 
> This makes sense except for being a CONFIG_ option not a boot parameter.
> If it's a boot parameter then the same kernel works for multiple systems
> and is general. If it's compile time then you have to build a custom
> kernel.
> 
> For some embedded stuff that might not matter (although I bet they'd
> prefer it command line/device tree too) but for something like an x86
> platform where you are deploying a standard vendor supplied kernel it's
> bad to do it that way IMHO.
> 
> In other words I think you should drop patch 3 but the rest is good.
> 

Same here. Can we assume a formal Reviewed-by: from you for the first two
patches ?

Thanks,
Guenter

> Alan
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