[systemd-devel] Triggering the HW Watchdog

[Lennart Poettering]

On Di, 27.02.18 12:44, D.S. Ljungmark (ljungmark at modio.se) wrote:

> Hi list!
> 
>  We're using systemd to control the hardware watchdog, and would want to
> induce fail state to _verify_ that the shutdown/reboot process works as
> expected.
> 
> How do we make systemd "fail" to ping the watchdog?

I figure you can send SIGSTOP to PID 1, no? (there are some signals
the kernel blocks for PID 1, but I think SIGSTOP is not among them,
please try)

> How do we control which states ( root fs not available, etc) cause
> systemd to not ping the hardware watchdog?

The watchdog is for detecting software hanging. Root fs not being
available does not really qualify as "software hanging". If you want
to reboot the machine if it fails to bring everything up, then use
JobTimeoutAction= on some suitable action, for example local-fs.target
or multi-user.target.

Lennart

-- 
Lennart Poettering, Red Hat