Pressing F7 during boot shows a black screen instead of console messages

[strugee]

Qubes OS version

R4.0

Affected component(s) or functionality

Plymouth

Brief summary

Pressing F7 during boot to show console messages shows a black screen instead.

To Reproduce
Steps to reproduce the behavior:

1. Boot
2. Wait until the splash screen shows up
3. Type in your disk encryption password
4. Press F7 to switch to the console

Not sure if step 3 is actually required but I didn't try to see what happens without it.

Expected behavior

I should see console messages about systemd services being started.

Actual behavior

Black screen.

Additional context

This appears to be further fallout from bug #3849. To be clear, I much prefer the current situation where I have a pretty splash screen, but this is still definitely a regression. I suspect it's because we're just working around the kernel bug by setting plymouth.ignore-serial-consoles and not actually fixing the root problem.

If you want to see the correct behavior, just press F7 on shutdown - it works as intended there.

Relevant documentation you've consulted

N/A - this is very clearly a regression

Related, non-duplicate issues

https://github.com/QubesOS/qubes-issues/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+boot+log+created%3A%3E%3D2019-01-01, https://github.com/QubesOS/qubes-issues/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+plymouth+f7+

[strugee]

Interestingly, today my Plymouth progress bar reached 100% and stayed there for a second or two. I hit F7 by habit to see what was going on, and saw a brief flash of logs before the display manager was started. It appears that this may start to work during very late boot.

[github-actions]

This issue is being closed because:

• This issue is on the "Release 4.0 updates" milestone.
• Qubes OS 4.0 reached EOL (end-of-life) over one year ago.
• There has not been any activity on this issue in over one year.

If anyone believes that this issue should be reopened and reassigned to an active milestone, please leave a brief comment.
(For example, if a bug still affects Qubes OS 4.1, then the comment "Affects 4.1" will suffice.)