|WATCHDOGD(8)||System Manager's Manual (smm)||WATCHDOGD(8)|
watchdogdis an advanced system and process supervisor daemon, primarily intended for embedded Linux and server systems. It can monitor critical system resources, supervise the heartbeat of processes and record deadline transgressions, and initiate a controlled reset if needed. When a system starts up,
watchdogddetermines the reset cause by querying the kernel. I case of system reset, and not power loss, the reset reason is available already in a file, stored by
watchdogdbefore the reset. This reset reason can be then be used by an operator or network management system (NMS) to put the system in an operational safe state, or non-operational safe state. /dev/watchdog, created automatically when the appropriate driver module is loaded. If your board does not have a WDT the kernel provides a "softdog" module which could be good enough. The idea is to have a process in userspace that runs in the background of your system, with the sole purpose of making sure the HW timer never expires by "kicking" it periodically. In case of system overload, when there is no more CPU time for the process to run, it fails to "kick" the kernel WDT driver, which in turn causes the WDT to reset the system.
watchdogdsupported more command line options, from v3.0
watchdogdhas been greatly simplified. Use watchdogctl(1) to query status and control
-n, log messages are printed to stdout.
watchdogd. Not supported in all WDT drivers due to HW limitations. Some drivers emulate support by keeping an in-kernel thread to continue kicking the WDT. Make sure to try it first, or verify the WDT driver source code.
watchdogdresponds to the following signals:
-xflag, otherwise same as PWR.
reloadcommand from watchdogctl(1).
watchdogdto maintain state across boots. If you want the status and reset reason, read /run/watchdogd.status instead.
watchdogdis ready to receive signals and register processes with the process supervisor API
watchdogdtimeout and period, and the reset reason
watchdogddetermined from this boot.
watchdogctlto connect to
watchdogdis an improved version of the original, created by Michele d'Amico and adapted to uClinux-dist by Mike Frysinger. It is maintained by Joachim Wiberg at GitHub.
|April 19, 2021||Debian|