here I go: my OS is Ubuntu 14.04. I was wondering about upgrading the kernel to the recent and latest stable 4.0.1 version (my current one is 3.16). Since I have already installed AMD Omega drivers (14.501.1003/ 14.12), I did remember that those drivers can be patched unofficially, so I patched the menctioned driver following this instructions here. So, based on that patch, it is possible to do some changes on AMD driver and make it compatible with latest kernel 4.0 in a safe way?
I've had problems with catalyst drivers when I upgraded to 15.04 (3.19.0-16-generic)
I suggest you remove the drivers using
sudo apt-get purge fglrx, reboot and reinstall the drivers available on repository using
sudo apt-get install fglrx or
sudo apt-get install fglrx-updates
more information, please check on this wiki: