Early display (plymouth) not working with Radeon cards

[jlj2]

Bug: During bootup backlight turns off.

Work around: After entering cryptography password correctly, can see certain journalctl(?) messages if the 'down arrow' is depressed, and can recover when darkened screen occurs if the 'down arrow' is again pressed 2-3 times immediately after backlight goes off.

NB: (1) Subgraph installed itself in legacy mode using MBR. Perhaps because original image was dd'd onto the installation medium (a USB stick) without a sync afterwards(??) (2) Other error messages appear in dmesg and journalctl; for example, Tor is disabled, but can connect. However, Subgraph is a pleasant experience despite the bugs.

Reports: journalctl dmesg

[xSmurf]

Do other Linux distribution behave the same way? What graphics card is in your machine?

[xSmurf]

Just double checked your logs, seems like you are on radeon, I'm not sure how plymouth likes that, can you try booting without splash in the kernel command line?

[jlj2]

Yes, the graphics are Radeon. Indeed, removing splash from the kernel line enabled the backlight to return on its own.

To keep these changes for the long term, please confirm which grub file to edit accordingly.

$ ls /etc/grub.d/
00_header        10_linux      30_os-prober      40_custom  README
05_debian_theme  20_linux_xen  30_uefi-firmware  41_custom

Then, run following?

$ sudo update-grub 

Thank you.

[xSmurf]

/etc/default/grub is the file you want to edit (then update-grub as you mentioned), but it's not impossible one of our packages managing configs (namely subgraph-grub-config) may blow it away in the future (you could potentially use dpkg-divert to prevent that). There may be a fix for plymouth to work with radeon, but I don't know it on top of my head, I've always stayed far away from ATI due to poor Linux support. Maybe @mckinney-subgraph has an idea?

[jlj2]

Backlight is failing again after 1-2 updates, yet splash doesn't appear to have returned to /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT="quiet apparmor=1 security=apparmor". Thank you very much for your suggestion with dpkg-divert, although I am not familiar with it. The work-around mentioned earlier still works.

[xSmurf]

Did you run update-grub after modifying the file?

[jlj2]

Yes, thanks.

[xSmurf]

Setting this as help wanted since we don't have hardware to test Radeon cards. For now I'll consider this fixed as disabling the splash returns minimal functionality. If someone knows what is needed to get Radeon to work from initramfs for Plymouth, let us known.