[systemd-devel] EXT: Re: Triggering the HW Watchdog

[Ray, Ian (GE Healthcare)]

> On 27 Feb 2018, at 16.12, D.S. Ljungmark <ljungmark at modio.se> wrote:
> 
> ( 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.
> 

This works for me: `gdb --pid 1'.


> 
>>> 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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