Comment # 6 on bug 1232727 from Thomas Zimmermann

Results so far:

1) I set up a qemu system with bochs and disk encryption to simulate the test
environment.

2a) If CONFIG_FB_DEVICE=y, plymouth displays the password prompt.


2b) If CONFIG_FB_DEVICE=n, booting the kernel without 'splash=silent' and
'quite' displays the boot-up messages in text mode (without plymouth). I can
enter the password as usual here.

2c) If CONFIG_FB_DEVICE=n, plymouth does not display the password prompt. It
appears to hang the system boot. No input is being accepted and the previous
kernel messages are being displayed.

But I do briefly see plymouth's 'spinning wheel' animation show up. This has to
run on DRM interface. So I assume that plymouth tries to display the prompt to
DRM as well, but fails and releases DRM entirely. Hence the system displays
obsolete kernel output and waits for the password.