Hello, I have an embedded system that does not have a real-time clock. I was hoping to run journald on it, but have run into some problems.
My problem is that my system currently does not guarantee a monotonically increasing time, and that seems to confuse journald a bit. Btw: I've tested this on v243-stable. (The system syncs over NTP, but there are some issues with this as well, more on that later) I originally found the problem since there were boots missing. E.g) # journalctl --list-boots -4 44cabeed86e34d09a4eca0dbff43b19f Mon 2020-08-03 14:27:59 UTC—Tue 2020-09-15 09:13:52 UTC -3 71164e7d83a9448c9e70bb59b6190a45 Tue 2020-09-15 09:13:52 UTC—Tue 2020-09-15 09:14:48 UTC -2 2e565a1c8dc84d4e95055e4cb4d0cc25 Tue 2020-09-15 09:14:48 UTC—Tue 2020-09-15 09:16:11 UTC -1 3c672d6fb8084f5fa5923a1ae5e0e53d Tue 2020-09-15 09:16:11 UTC—Tue 2020-09-15 09:31:52 UTC 0 afc0d98f275e4999aa061c7bb61b85d2 Tue 2020-09-15 09:33:35 UTC—Tue 2020-09-15 09:56:12 UTC # journalctl -F _BOOT_ID 44cabeed86e34d09a4eca0dbff43b19f 71164e7d83a9448c9e70bb59b6190a45 1465a36c753f43df92bcc0a76d8e763e 2e565a1c8dc84d4e95055e4cb4d0cc25 3c672d6fb8084f5fa5923a1ae5e0e53d afc0d98f275e4999aa061c7bb61b85d2 302cc41b146c4b3c88f06df102913c3f I've poked around in the source code think I found the reason for this: journal_file_compare_locations() (in journal-file.c) compares seqnum if within the the same seqnum_id, but uses current_realtime if not within the same seqnum_id. Since my realtime can't be trusted I sometimes have journalfiles within the same seqnum_id which "jumps" back in time. That combined with the traversal in real_journal_next() gives a stochastic behaviour. I have tried fixing my clock to give a monotonically increasing clock. But: I want my system to boot as fast as possible, even without a NTP-syncronized time. And I've noticed that if I shutdown before getting a NTP time timesyncd will not have touched the "clock" file, and I end up in the situation above. Now to my question: What is the best practice in using journald on systems without RTC? It it even "supported"? /Regards, Magnus Berglund
_______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/systemd-devel