Created attachment 142831 [details]
dmesg with 4.20.0-042000rc6-generic kernel
Various temporary UI freezes when booting Ubuntu 18.10.
dmesg reports various amdgpu warnings and errors.
Also tested with 4.20.0-042000rc6-generic kernel
Original launchpad bug report:
With 4.20.0-042000rc7-generic it is actually worse. The system hangs with a black screen while booting with power adapter connected. Without power adapter it does boot.
Created attachment 142842 [details]
Kern.log of failed boot (black screen) with 4.20.0-042000rc7-generic
Created attachment 142843 [details]
dmesg with 4.20.0-042000rc7-generic without ac adapter
Use latest AMd wip kernel, firmware files and Oibaf ppa.
With v5.0-rc1 the system hangs with a black screen after I login at gdm when the power adapter is connected
Created attachment 143004 [details]
kern.log using kernel v5.0-rc1 with black screen after login with power adapter plugged in
Without the power adapter connected v5.0-rc1 hangs with black screen at login screen before actual login.
Created attachment 143016 [details]
kern.log using kernel v5.0-rc1 with black screen before login without power adapter plugged in