[systemd-devel] --Reboot-- lines in journal

[Dave Howorth]

What do --Reboot-- lines in the journal mean and how do they get there?

I can't find any explanation on
https://www.freedesktop.org/software/systemd/man/journalctl.html or
related pages I've tried.

I should explain why I'm interested. On my openSUSE box, I can see for
example:

# journalctl --list-boots
-1 3c9ab70ade084dfab277efe733e18949 Mon 2020-03-02 23:44:11 GMT—Sun 2020-03-29 08:54:38 BST
 0 c56183ea7877444a8252dd89a32b31f3 Sun 2020-03-29 09:15:30 BST—Thu 2020-05-14 13:16:49 BST
# journalctl | grep Reboot
-- Reboot --
# 

Which looks fairly sane with what I think I should expect. But on two
Raspberry pis that I have with persistent logging enabled they both
have a huge excess of --Reboot-- lines. For example:

$ sudo journalctl --list-boots
-3 a9346655ca5d4700ab470bfd1b94d5da Thu 2019-02-14 10:11:59 GMT—Wed 2020-05-13 18:31:22 BST
-2 c4f8ab5ec73b40818b1607b3436b90b5 Wed 2020-05-13 18:32:51 BST—Wed 2020-05-13 18:46:29 BST
-1 0af9c854355f4a12a64dd00e6d3d98c1 Wed 2020-05-13 19:32:57 BST—Wed 2020-05-13 22:33:24 BST
 0 fc5b35dbb3604dfbb4e2cdc99e117a75 Wed 2020-05-13 22:33:24 BST—Thu 2020-05-14 12:46:07 BST
$ sudo journalctl | grep Reboot | wc
   1667    5047   22095
$

What do the apparently excess 1664 --Reboot-- messages mean?

I can post more journal content if required.