Watchdog

Setup watchdog in Ubuntu.

Enable Watchdog

Watchdog is disabled by default, use the commands below to enable it.

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khadas@Khadas:~$ sudo ln -s  /lib/systemd/system/watchdog.service /etc/systemd/system/multi-user.target.wants/watchdog.service
khadas@Khadas:~$ sudo systemctl enable watchdog.service
khadas@Khadas:~$ sudo systemctl start watchdog.service
Tips

You need to create the service link manually, due to a Debian bug.

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khadas@Khadas:~$ sudo systemctl enable watchdog.service
khadas@Khadas:~$ sudo systemctl start watchdog.service

Check Watchdog Status

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khadas@Khadas:~$ systemctl status watchdog.service 
● watchdog.service - watchdog daemon
     Loaded: loaded (/lib/systemd/system/watchdog.service; enabled; vendor pres>
     Active: active (running) since Fri 2021-03-26 10:00:38 UTC; 15min ago
    Process: 3381 ExecStartPre=/bin/sh -c [ -z "${watchdog_module}" ] || [ "${w>
    Process: 3382 ExecStart=/bin/sh -c [ $run_watchdog != 1 ] || exec /usr/sbin>
   Main PID: 3385 (watchdog)
      Tasks: 1 (limit: 2932)
     Memory: 864.0K
     CGroup: /system.slice/watchdog.service
             └─3385 /usr/sbin/watchdog -s -v -c /etc/watchdog.conf

Mar 26 10:15:38 Khadas watchdog[3385]: still alive after 120 interval(s)
Mar 26 10:15:39 Khadas watchdog[3385]: still alive after 121 interval(s)
Mar 26 10:15:40 Khadas watchdog[3385]: still alive after 122 interval(s)
Mar 26 10:15:41 Khadas watchdog[3385]: still alive after 123 interval(s)
Mar 26 10:15:42 Khadas watchdog[3385]: still alive after 124 interval(s)
Mar 26 10:15:43 Khadas watchdog[3385]: still alive after 125 interval(s)
Mar 26 10:15:44 Khadas watchdog[3385]: still alive after 126 interval(s)
Mar 26 10:15:45 Khadas watchdog[3385]: still alive after 127 interval(s)
Mar 26 10:15:46 Khadas watchdog[3385]: still alive after 128 interval(s)
Mar 26 10:15:47 Khadas watchdog[3385]: still alive after 129 interval(s)
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Set Watchdog Timeout

The default timeout is 15 seconds, you can edit the file /etc/watchdog.conf to change the value watchdog-timeout.

Restart the watchdog service to take effect.

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$ sudo systemctl restart watchdog

Test Watchdog

  • Trigger a Kernel crash.
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khadas@Khadas:~$ sudo -i
root@Khadas:~# echo c > /proc/sysrq-trigger

If watchdog was setup successfully, the system will automatically reboot after the Kernel crash, in accordance with the timeout you have set above.

  • Kill the Watchdog daemon

You can also kill the watchdog daemon to prevent an automatic restart after a Kernel crash.

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khadas@Khadas:~$ sudo pkill -9 watchdog
khadas@Khadas:~$ sudo pkill -9 wd_keepalive
khadas@Khadas:~$
khadas@Khadas:~$
khadas@Khadas:~$ G12B:BL:6e7c85:2a3b91;FEAT:E0F83180:402000;POC:F;RCY:0;EMMC:0;READ:0;0.
bl2_stage_init 0x01
bl2_stage_init 0x81
hw id: 0x0000 - pwm id 0x01
bl2_stage_init 0xc1
bl2_stage_init 0x02

L0:00000000
L1:20000703
L2:00008067
L3:14000000
B2:00402000
B1:e0f83180

TE: 207260

BL2 Built : 15:22:05, Aug 28 2019. g12b g1bf2b53 - user@domain
...

Disable Watchdog

  • Disable the Watchdog daemon
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khadas@Khadas:~$ sudo systemctl disable watchdog
khadas@Khadas:~$ sudo reboot
  • Disable Watchdog driver [Optional]

You can also disable the watchdog driver. Edit /boot/env.txt and remove watchdog in the overlays node, then save and reboot the system.