(from a 'private' email sent to me)
The manual page systemd-udevd.service(8) documents the kernel command line, and lists `udev.log_level=` and `rd.udev.log_level=`. Maybe that gives more information.
alas, it's already set to =debug. here, atm
cat /proc/cmdline
"... rd.debug=0 rd.shell=1 rd.auto=1 rd.udev.log_priority=debug systemd.log_target=kmsg printk.devkmsg=on systemd.log_level=info ..."
^^^^^^^^^^^^^^^^^^^^^^^^^
which is why, in my OP, is shown,
journalctl -b | grep systemd-udevd | grep /etc
Dec 20 19:24:16 dev systemd-udevd[522]: Trying to open "/etc/systemd/hwdb/hwdb.bin"...
Dec 20 19:24:16 dev systemd-udevd[522]: Trying to open "/etc/udev/hwdb.bin"...
Dec 20 19:24:16 dev systemd-udevd[522]: Reading rules file: /etc/udev/rules.d/11-dm.rules
...
where, the rules logged as IN /etc/udev/rules.d/ actually are NOT sourced from that path.
it's NOT that udev isn't being logged.
it's that udev rules ADDED aren't logged.
