[OpenWrt-Devel] watchdog against router crash freezes?

[Marcel Partap]

[…]

> https://openwrt.org/docs/guide-developer/ubus/system has watchdog
> information, but also, bear in mind that it just uses the normal
> kernel infrastructure for watchdogs, so there's no particular
> openwrt specific information.
That page lacks the information that a watchdog mechanism is included and active by default in OpenWRT's procd; I didn't realize that... the kernel log is very sparse:
> [    9.751453] procd: - early -
> [    9.754508] procd: - watchdog -
> [   10.524521] procd: - watchdog -
> [   10.528108] procd: - ubus -

At the bottom of that ubus doc page, it does link to a blog entry from march 2018 but the URL is dead. It is available from the archive though:
https://web.archive.org/web/20180821003756/http://kernelreloaded.com/manually-controlling-openwrt-hardware-watchdog/

> Originally OpenWrt used watchdog daemon tool to manage hardware watchdog (there is a very detailed man page explaining what exactly watchdog daemon does).
> 
> If for any reason watchdog process stopped 'tickling' hardware watchdog trough /dev/watchdog device the hardware watchdog would trigger a hardware reset.
> 
> The confusion started when in 2013 OpenWrt developers removed watchdog daemon and implemented watchdog feature into procd.
> 
> The biggest issue was that there was no mechanism to take control back from procd so that you can manually tickle or not tickle hardware watchdog. 

This should be in the Developer Guide, also maybe also give the information that `ubus call system watchdog` will show current watchdog settings.
 
I still don't know if a hardware watchdog is active or if it is the kernel's softdog.. all I know is the router freezes frequently so it is probably broken beyond the point of where a watchdog setup will help.

Best Regards,
#marcel

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