2.76 - How to use ATI/AMD GPU without Linux proprietary driver? I'm running Kubuntu 15.10 with Blender 2.76 64-bit. PC is a laptop with the ATI Mobility Radeon HD5850 graphics card. (specs: kernel 4.2.0-16-generic, 12GB RAM, 2GB GPU RAM, KDE Plasma 5.4.2)

I can't install the fglrx proprietary driver, otherwise Kubuntu won't boot; I have to use the open-source driver.

My question is: is there a way I can utilize the GPU processing for Blender (using Cycles engine) in Ubuntu (Kubuntu, or any of Ubuntu's flavors) without install the ATI/AMD proprietary driver?

Thanks in advance!
I'm affraid that is not possible. Apparently (checked on luxrender) the GPU is only detected by blender using privative drivers, but even knowing that cycles is not fully capable with ATI/AMD cards. The kernel must compiled on the fly before start rendering and you can't use (even with the propietary drivers) volume absorption or scattering with the GPU and you still have to use CPU for it.
Blender works better with Nvidia CUDA i got the experience using blender on linux for several years and comparing with windows. and the results with AMD cards are disapointing.