The family of processors Intel Atom E38xx has an internal Watchdog, supported in Linux with the driver iTCO_wdt. This driver is installed by default in Ubuntu 14.04 and Ubuntu 16.04. Inserting the module allows the daemon watchdog to control the internal Watchdog.
The Linux kernel can reset the system if serious problems are detected. This can be implemented via special watchdog hardware, or via a slightly less reliable software-only watchdog inside the kernel. Either way, there needs to be a daemon that tells the kernel the system is working fine. If the daemon stops doing that, the system is reset.
watchdog is such a daemon. It opens /dev/watchdog, and keeps writing on it often enough to keep the kernel from resetting, at least once per minute. Each write delays the reboot time another minute. After a minute of inactivity the watchdog hardware will cause the reset. In the case of the software watchdog the ability to reboot will depend on the state of the machines and interrupts.
More information in: https://linux.die.net/man/8/watchdog
For simplicity in this tutorial it is explained how to install and configure watchdog over Ubuntu 16.04 on E38xx watchdog (it will be called WDT from now on).
1. Installation of watchdog daemon
In Ubuntu install the package with the command:
apt-get install watchdog
2. Configuration of watchdog daemon
watchdog configuration daemon is done via /etc/watchdog.conf file.
There are a lot of parameters which can be configured, but for a simple watchdog configuration.
The full list of configuration parameters can be found in https://linux.die.net/man/5/watchdog.conf).
Configuración watchdog (/etc/watchdog.conf)
watchdog-device = /dev/watchdog interval = 1 watchdog-timeout = 15