<div dir="auto">So then where does journald logs its own messages if he wants to?</div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, 27 Aug 2021, 13:37 Lennart Poettering, <<a href="mailto:lennart@poettering.net">lennart@poettering.net</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Fr, 27.08.21 10:01, Mantas Mikulėnas (<a href="mailto:grawity@gmail.com" target="_blank" rel="noreferrer">grawity@gmail.com</a>) wrote: > On Fri, Aug 27, 2021, 08:52 Nishant Nayan <<a href="mailto:nayan.nishant2000@gmail.com" target="_blank" rel="noreferrer">nayan.nishant2000@gmail.com</a>> > wrote: > > > I have just started to learn journald and in its main function (in > > journald.c) I encountered a function call "log_set_prohibit_ipc(true);" > > In systemd source, I can see the declaration in src/basic/log.h:/* > > > > If turned on, then we'll never use IPC-based logging, * i.e. never log to > > syslog or the journal. We'll only * log to stderr, the console or kmsg > > */void log_set_prohibit_ipc(bool b); > > > > I did not get this because Journald not writing to journal itself by > > default is strange, isn't it? > > What is the reason behind it? > > > > My understanding is that the point isn't to prevent logging to journal, but > to prevent logging *through IPC* specifically, i.e. make sure journald > doesn't try to create loopback connections to its own sockets. The journald > daemon is single-threaded, so if it tries to connect to itself, it'll > deadlock. > > But also if journald wants to log a critical error (e.g. running out of > space or something like that), then it can't really *rely* on journal still > working... > > Afaik, messages written to kmsg will be imported back into the journal > anyway, but that happens asynchronously so it's fine. The above describes exactly how it is, and why journald turns of logging via IPC. journald should not be a client to itself. Lennart -- Lennart Poettering, Berlin </blockquote></div>