We've validated 17.10 against Ubuntu 16.04.02 and Kernel 4.8, so I recommend to use these. Using a different version will cause issues as we don't test Xubuntu.
I have the same problem. Used amdgpu-pro 17.10 Ubuntu 16.04.02 and Kernel 4.8.
All I got was a black screen . I had to reinstall Ubuntu again.
I thought R9 380 was supported