You should have installed Ubuntu 14.04 development instead -- that's the first thing I did when I got a new Kabini APU laptop (A4-5000) in December. Worked perfectly out of the box with open source drivers ever since. The only thing really holding it back is the horrible performance of GLAMOR, which is still a lot faster than Catalyst's even worse 2D rendering.
No announcement yet.
Radeon 8000M problematic on Linux?