what mean 'journal-or-kmsg' systemd 'log-target'?

[Frantisek Hanzlik]

poma wrote:
> On 10.09.2013 12:01, Frantisek Hanzlik wrote:
>> poma wrote:
>>> On 10.09.2013 10:03, Frantisek Hanzlik wrote:
>>>> Know anyone what exactly mean 'journal-or-kmsg' value for '--log-target'
>>>> systemd option or 'LogTarget=' /etc/systemd/system.conf option?
>>>>
>>>> man page for F19 systemd v204-9 mention it, but without any explanation.
>>>> (as well for 'syslog-or-kmsg' value)
>>>>
>>>> TIA, Franta Hanzlik
>>>>
>>>
>>> You should try carefully to re-read the section of manual, it points to
>>> the "main" manual. ;)
>>> man 5 systemd-system.conf -> man 1 systemd
>>>
>>> man 7 signal - SIGRTMIN
>>>
>>>
>>> poma
>>
>> You think this piece in 'SIGNAL' systemd man page paragraph?:
>>
>> SIGRTMIN+26, SIGRTMIN+27, SIGRTMIN+28, SIGRTMIN+29
>>   Sets the log level to journal-or-kmsg (or console on SIGRTMIN+27,
>>   kmsg on SIGRTMIN+28, or syslog-or-kmsg on SIGRTMIN+29), as controlled
>>   via systemd.log_target=journal-or-kmsg (or systemd.log_target=console
>>   on SIGRTMIN+27, systemd.log_target=kmsg on SIGRTMIN+28, or
>>   systemd.log_target=syslog-or-kmsg on SIGRTMIN+29) on the kernel
>>   command line.
>>
>> where You see what is doing 'journal-or-kmsg' settings?
>>
>> Fr. Hanzlik
>>
> 
> Actually you're right, it's not explained. At least not the way you expect.
> With all the repeated explanations of all terms, the manual would be
> turned into an encyclopedia what wouldn't be bad at all. :)
> Just, try to find someone who'll do it. :)
> So, try to figure out the meaning of the words "journal" & "kmsg".
> This is a good example of the use,
> http://freedesktop.org/wiki/Software/systemd/Debugging/
> 
> 
> poma

I am afraid that Your both mails hints are useless (for me),
You perhaps not perceived what I ask.

But when I rightly grasp to systemd sources, then 'journal-to-kmsg' mean
1) in log opening time it tries open journal and then kmsg channel;
last what succeed will be taken as log target (weird?)
2) in write to log time, when record to journal should be done and
it fail, then channel to kmsg is opened and report is recorded to
kernel message buffer. But as according to 1) in 'normal' circumstances
with 'journal-to-kmsg' is opened only kmsg channel, this behavior is
tricky. Either I not uderstand this correctly, or there is something
broken - maybe systemd TODO file contain notice 'journal-or-kmsg is
currently broken? See ...'.

Maybe systemd maintainers at some time describe these options and
their behavior, IMO for now there is essential fix other, more
important things.

Franta Hanzlik