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 to 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.
Thanks for reference.
reference : https://www.systutorials.com/docs/linux/man/8-watchdog/
