the openCL component of this problem is addressed here: https://bugs.freedesktop.org/show_bug.cgi?id=99856#c24 related Debian bug report: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=857591 the unrelated Blender bugs are being discussed here: https://developer.blender.org/T50522 Hopefully, the solutions now available can be quickly applied. -- Ian Bruce