Comment 35 for bug 1827884

I am seeing a similar problem.

Linux Mint 18.3 XFCE, Lenovo Thinkpad T60 i686 / ATI Radeon RV515 GPU

After upgrade to kernel 4.15.0-48, I get a black screen and frozen keyboard once the boot splash screen exits, when the login screen should appear. There is no mouse pointer, and I can't escape with ctrl-alt-f1, ctrl-alt-backspace, etc. If I leave the system running for a while, there is occasional disk activity, and syslog entries with later time stamps, indicating that the kernel is still running, but the X server is frozen.

Same thing with latest kernel 4.15.0-50.

I can boot into the previous kernel 4.15.0-47 with no problems.

If I boot into run level 3 (terminal only, no GUI) by editing the Grub kernel command line, the system will boot, but enters the same frozen state if I then start the GUI with 'sudo service lightdm start' (which works fine with the previous 4.15.0-47 kernel).

If I add "nomodeset" to the kernel command line, the system will boot into the GUI. In this case Xorg.0.log shows that the X server unloads the Radeon driver (which will not run without KMS) and loads the fallback VESA driver instead. I.e., on my computer the bug affects the Radeon driver but not the VESA driver. (However, this is not a solution for me because the VESA driver doesn't handle my 1400x1050 screen resolution correctly.)

One other thing - the bug happens maybe 9 times out of 10 but not every time. On the occasional successful boot, once the GUI comes up without freezing, everything seems to work OK.