[systemd-devel] Triggering the HW Watchdog

[D.S. Ljungmark]

( re-send as I forgot the list )

On 27/02/18 13:20, Lennart Poettering wrote:> 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)

It seems that SIGSTOP is being filtered, because nothing appears to
happen, and the system certainly isn't rebooting.


>> 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
Thanks,
  I'm trying to get to a state where the machine fails over and triggers
watchdog on known things, rather than triggering the rescue shell or
similar.


I'll try with a jobtimeout on multi-user.

//D.S.


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