After the last dom0 update a few days ago, the system doesn’t reach the Grub boot menu anymore. The screen stays completely black during boot and the monitor reports ‘no signal’ after a few seconds and auto-switches off after a few more.
I managed to get to a Grub command shell by pushing the esc key immediately after switching the machine on. The ‘reboot’ command in this shell worked flawlessly much to my surprise, it started and finished the normal Qubes boot sequence. Quite a step up from booting into a black screen and having to pull the plug.
Any ideas what might cause the black screen after boot and how to remedy this? Journalctl -b in Dom0 doesn’t even show the failed boot attempts where I ran into the black screen.
I’m on a Cezanne AMD 5700G CPU with integrated Vega 8 Graphics. 4.2.4 system has been stable for years.
Maybe something in the BIOS settings for the GPU can help solve the problem. The BIOS has some settings for the integrated graphics, but I don’t remember those from my head. I don’t know if anything from Qubes is executed before the GRUB. I have the same CPU and the latest update to dom0 seems to have made issues with the integrated amd gpu worse for me, but these issues are probably unrelated.
May you double check bios settings for SVM Mode?
Maybe after dom0 kernel update, there was an issue on boot and AMD motherboard self-reset to defaults, in such case SVM may be disabled and it result in black screen at boot.
Because the problems occur this early, I am also considering some sort of weird UEFI problem, yet I don’t think this one is plausible considering the fact the system behaves normal and is stable after finishing an also normal boot sequence from the GRUB shell prompt. The problems occured during the very first boot after the Dom0 update.
I was thinking of NB Configuration -> Primary Video Device setting. This came to my mind because early on with my multi GPU combination I had problems getting the motherboard activating the right GPU on boot. The integrated GPU wasn’t enabled if it found a discrete GPU. I’m not sure if this was the only setting I had to change.
The latest Dom0 update installed the 6.18.15 kernel which probably has become the new LTS kernel. It’s very likely the booting into a black screen is caused by this. AMD integrated new drivers in this kernel which should be an improvement for the AMD GPU, but there are more reports about pretty serious bugs.
I’ll have to revert to the previous LTS kernel 6.12.64. Since booting is not an option, I’ll have to edit Grub in Dom0. The Qubes documentation about this is weird: How to install software in dom0 — Qubes OS Documentation since this procedure involves a reboot!
If you’re not reaching GRUB, you’re not booting yet. The Linux kernel has no impact. Maybe the GRUB timeout and other settings have changed and you’re moving past the GRUB menu without noticing and then the boot fails to a black screen? You mentioned you need to press ESC to get to the GRUB shell. Try rebuilding GRUB anyway.
I was originally worried my integrated GPU started crashing (Dumping IP State) without stressing the CPU, but it seems it has worked like before for a few days now under normal heavy loads. I booted once to the older kernel in between. I’m pretty sure it crashes if I stress it, but that happened with the older kernel too. The problem after the integrated GPU has had its episode seems something that is actually happening in xen-blkback and should be recoverable, because I can move the mouse cursor on screen very choppily and the sound keeps playing choppy cuts (journalctl is getting new lines too) but nothing else (keyboard or power button) does anything.