I've been running systems up to Buster and have always had the 'quiet' option in the grub settings to show the regular service startup messages (the colored ones showing [ok] and such but not all the dmesg stuff). I just upgraded a server to bullseye and there are zero messages being displayed now except an immediate message about not being able to use IRQ 0. Worse, google can't seem to find any information on this. If I remove the quiet option from grub then I see those service messages again, along with all the other stuff I don't need.
What is broken and how do I fix this issue? I assumed it would be safe to upgrade by now but this seems like a pretty big problem if I ever need to troubleshoot a system.
[Edit] In case anyone else finds this post searching for the same issue… Apparently the trick is that now you MUST install plymouth, even on systems that do not have a desktop environment. For whatever reason plymouth has taken over the job of displaying the text startup messages now. Keep your same grub boot parameters (quiet by itself, without the splash option) and you will get the old format of startup messages showing once again. It’s been working fine the old way for 20+ years but hey let’s change something just for the sake of confusing everyone.
[Edit 2] Thanks to marvin below, I now have a final solution that no longer requires plymouth to be installed. Edit /etc/default/grub and add systemd.show_status=true to GRUB_CMDLINE_LINUX_DEFAULT. In my case to full line is:
GRUB_CMDLINE_LINUX_DEFAULT="quiet systemd.show_status=true"
Don't forget to run update-grub after you save your changes.
I finally had a chance to get back to this build, and wanted to thank you for this solution. It does indeed work even after removing plymouth and I'll update the OP as the best solution.