ADLINK CSA-5100 - Manual (Page 33)

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CSA-5100
5.3 SuperIO Watchdog Driver & API
A SuperIO Watchdog Driver and API (Linux only) is available to enable LAN bypass by
software control and to reboot the system when a crash occurs (LAN bypass can be enabled
on system restart). To make use of this feature, first install a Linux OS, and then install the
SuperIO Watchdog Driver.
5.3.1 Overview
A Watchdog Timer (WDT) is a hardware circuit that can reset the computer system in case of
a software fault. Usually a user space daemon will notify the kernel watchdog driver via the
/dev/watchdog special device file that user space is still alive, at regular intervals. When such
a notification occurs, the driver will usually tell the hardware watchdog that everything is in
order, and that the watchdog should wait for period of time to reset the system. If user space
fails (RAM error, kernel bug, etc.), the notifications cease to occur, and the hardware
watchdog will reset the system (causing a reboot) after the timeout occurs.
The figure below depicts all logical blocks in the CSA-5100 SuperIO watchdog
implementation.