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Date: Tue, 5 Jun 2007 08:38:54 -0700
From: Andrew Sharp <andy.sharp@onstor.com>
To: "Tim Gardner" <tim.gardner@onstor.com>
Subject: Re: watchdog device
Message-ID: <20070605083854.06e4b50d@ripper.onstor.net>
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You can disable it simply by closing the file descriptor.

Cheers,

a


On Mon, 4 Jun 2007 20:22:02 -0700 "Tim Gardner"
<tim.gardner@onstor.com> wrote:

> Thanks Andy. Very close to what we want but not quite.
> We need to be able to enable/disable the watchdog as well as set the
> timeout value. I will probably just steal the source for this driver
> and add a few ioctls.
> 
> ________________________________
> 
> From: Andy Sharp
> Sent: Mon 6/4/2007 4:15 PM
> To: Tim Gardner
> Subject: watchdog device
> 
> 
> 
> Here is the kernel help text for the watchdog device.  You can
> configure the software watchdog by adding support for SOFT_WATCHDOG.
> CONFIG_WATCHDOG is already set to 'y'.  So, add a line
> CONFIG_SOFT_WATCHDOG=y
> after the CONFIG_WATCHDOG line in .config and do a 'make' in
> linux-mips-2.6, or a 'make kernel-build' in the directory above
> (cougar/linux/kernel).
> 
> The user process then has to open and write to the file descriptor at
> least once a minute or the kernel will reboot.  I haven't tested it
> ~:^)
> 
> 
> CONFIG_WATCHDOG=y
> 
> If you say Y here (and to one of the following options) and create a
> character special file /dev/watchdog with major number 10 and minor
> number 130 using mknod ("man mknod"), you will get a watchdog, i.e.:
> subsequently opening the file and then failing to write to it for
> longer than 1 minute will result in rebooting the machine. This
> could be useful for a networked machine that needs to come back
> on-line as fast as possible after a lock-up. There's both a watchdog
> implementation entirely in software (which can sometimes fail to
> reboot the machine) and a driver for hardware watchdog boards, which
> are more robust and can also keep track of the temperature inside
> your computer. For details, read
> <file:Documentation/watchdog/watchdog.txt> in the kernel source.
> 
> The watchdog is usually used together with the watchdog daemon
> which is available from
> <ftp://ibiblio.org/pub/Linux/system/daemons/watchdog/>. This daemon
> can also monitor NFS connections and can reboot the machine when the
> process table is full.
> 
> 
> 
> 
> CONFIG_SOFT_WATCHDOG=[y|m]
> 
> A software monitoring watchdog. This will fail to reboot your system
> from some situations that the hardware watchdog will recover
> from. Equally it's a lot cheaper to install.
> 
> To compile this driver as a module, choose M here: the
> module will be called softdog.
> 
> 
> 
> CONFIG_WATCHDOG_NOWAYOUT=n
> 
> The default watchdog behaviour (which you get if you say N here) is
> to stop the timer if the process managing it closes the file
> /dev/watchdog. It's always remotely possible that this process might
> get killed. If you say Y here, the watchdog cannot be stopped once
> it has been started.
> 
> 
