How to determine whether a hardware or a software watchdog is implemented on the machine?

Question

I have an embedded computer I am trying to develop on and I wanted to know if the watchdog it has is a software watchdog or if it is a hardware watchdog.

First I checked and I saw that /dev/watchdog is present inside /dev. But I did not see a watchdog process when I issued ps. So I installed a watchdog daemon (or driver?) and verified that a watchdog is running, again I used ps.

My problem now is I have no idea whether this is a hardware or software watchdog... there is a .conf file and also a process called /usr/sbin/watchdog owned by root. In case that info helps.

TIA!

Niko

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The dmidecode does NOT show the watchdog information on this machine, whereas it does show watchdog present info on my peer's laptop:

On the other hand on my computer the /dev folder is NOT showing the watchdog entry nor does lsmod|grep softdog show anything.

From here: http://www.sat.dundee.ac.uk/psc/watchdog/watchdog-testing.html

Checking for the Watchdog Hardware If you have successfully loaded the watchdog hardware's driver module (or the 'softdog' > emulator) then you should see the entry in /dev corresponding to this. For example:

ls -l /dev/watch*
crw------- 1 root root 10, 130 May 13 16:27 /dev/watchdog

I need to know which module do I need to load for hardware watchdog and for that I need to know what module does my hardware watchdog require!

One board I have is: CAPA830 with Ubuntu 12.04 on it
and other is:
3.11.0-15-generic #25~precise1-Ubuntu SMP Thu Jan 30 17:39:31 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

dmesg on the second machine shows:
NMI watchdog: enabled on all CPUs, permanently consumes one hw-PMU counter.

Answer 1

If you are talking about Linux's software watchdog then softdog module should be loaded, which you can verify with

$lsmod|grep softdog
softdog                13319  0 

Answer 2

Only one watchdog could be present per system. That could be either a software watchdog or a hardware watchdog. Generally when a watchdog(software/hardware) is inserted, the kernel creates a device node as /dev/watchdog. You can check if the file is present or not. If yes, watchdog is active on your machine, else not.

Now, the /usr/bin/watchdog that your were referring to is a watchdog daemon. It runs in the background and continuously reports the system status to the watchdog(either implemented as hardware/software).

For more info on the daemon, please refer to the man page of watchdog man watchdog.

To check if it is a hardware/software watchdog, just do :

$ lmsmod | grep softdog

If you get an output, your system is running a software watchdog, else a hardware watchdog is implanted into the system. This check is to be done, provided, that you have a node named /dev/watchdog present.

Hope this helps.