Honestly, it's extremely difficult to update the kernel since it's usually tied to the BSP the SoC vendor is providing. Also, you gotta keep in mind the difficulties associated with the lazy 3rd parties providing drivers for a single kernel version, making updates almost impossible. -- Disclosure : I work for an OEM as a system architect, and it's been one of my goals to try and get newer kernel versions running. (Suffice to say I failed so far)