On Fri, Aug 27, 2021, 08:52 Nishant Nayan <nayan.nishant2000@xxxxxxxxx> 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.
