Make Plymouth hide ALL messages on boot, reboot, halt. Plymouth ignores --no-boot-log flag

[Thomas Weissel]

running a fresh install of kubuntu 22.04
plymouth version: 0.9.5+git20211018-1ubuntu3

What should happen:
no bootmessages should be printed to console in the first place

What actually happens:
When Plymouth quits the last 2-3 messages are visible - so some boot messages are printed to console never the less

on shutdown for example i get:
[OK] Reached target Late Shutdown Services
[OK] Finished System Power Off
[OK] Reached target System Power off

it seems to be absolutely impossible to hide all boot messages
i've done everything from this arch wiki site (and more) to get a silent boot: https://wiki.archlinux.org/title/silent_boot
(this makes all acpi warnings and more go away.. but the [OK] reached/finished messages are not affected by those kernel parameters (this should also be fixed)

My Kernelparameters:quiet splash fbcon=nodefer rd.systemd.show_status=0 systemd.show_status=0 vt.global_cursor_default=0 loglevel=0 rd.udev.log_level=0 udev.log_level=0 rd.systemd.log_level=0 systemd.log_level=0

What part of the system throws these messages ?
i thought it is systemd?
so i even edited files in /usr/lib/systemd/system in order to set the StandardOutput to null for all of the halt and reboot and plymouth scripts

and i edited the plymouth start and stop scripts and added -no-boot-log but plymouth totally ignores this flag and still logs everything to console and to /var/log/boot.log

this defies the whole purpose of plymouth if plymouth itself spams the console with messages and if it's systemd why doesn't it respect the kernel parameters

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1970069, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

[Thomas Weissel (valueerror)]

i'm quite sure that this is NOT a duplicate.. the other bug refers to some kernel upgrades that lead to error messages with acpi and usb devices in 22.04 (i also have these kernel messages but they are easily hidden with the kernel boot parameters i've mentioned above - especially loglevel=0)

my bugreport says that even with all of these kernel parameters in place i still have the
[OK] Finished ServiceXY
messages.

so they are related (because if plymouth would do it's job it wouldn't matter that those boot parameters are ignored) but they actually target two different problems

also i believe that these messages (the ones i am talking about) aren't kernel messages but systemd or plymouth logs
they are written to boot.log

[Daniel van Vugt (vanvugt)]

The exact log messages are irrelevant. And where they come from is also probably irrelevant, be it kernel or daemons. Please feel free to generalize the description of bug 1970069.

[Thomas Weissel (valueerror)]

well i'm getting to the roots of this step by step.. but as far as i see it now i reported a bug where kernel parameters that set the loglevel are beeing ignored by system daemons that monitor the init process.

the other bug is about plymouth not hiding these messages.

so the headline of this bug should be corrected.. or.. i'll do another report that pinpoints the problem better
because it's probaly not even a plymouth problem ?