I recently tried to install some new graphics drivers on my laptop running Ubuntu 18.04.4 LTS, but upon rebooting I ended up on a log screen (like you'd see in recovery) constantly flashing back and forth to a black screen. I have discerned that this is due to the Xorg server being unable to start. In the Xorg.0.log there are several notable error lines:
(EE) systemd-logind: failed to get session: PID 12463 does not belong to any known session
...
(II) RADEON: Driver for ATI/AMD Radeon chipsets:
(long list of GPUs)
(EE) No devices detected.
...
(EE) open /dev/dri/card0: no such file or directory
(WW) Falling back to old probe method for modesetting
(EE) open /dev/dri/card0: no such file or directory
...
(EE) Screen 0 deleted because of no matching config section.
...
(EE) AIGLX: reverting to software rendering
The server ends up terminating, then restarting, etc.
My computer uses an AMD Ryzen 5 3500U with integrated graphics. lspci indicates that:
...
03:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Picasso (rev c2)
...
Note: I'm performing these commands from the recovery mode root shell.
