So I was having problems with the latest Ubuntu kernel in Ubuntu 18.04.2 and installed 18.04.1 from old-releases page
Now I wonder if I can update the kernel and have a good deal but I guess it will upgrade to the latest which doesn't work but I could manually install newer 4.15 kernels.
I have the initial Kernel for 18.04.1, I think it's 4.15.0-36 (but will confirm the version later) working with the latest driver version. So I think it's a good idea to compile the Kernel versions that are working in this post so that users can do the adjustments to make AMDGPU-PRO or AMDGPU work with Ubuntu.
18.50 - 4.15.0-47-generic Ubuntu 18.04.2 LTS