[noggin]

That actually made me stop and think for a bit about how the Raspberry Pi runs 4.x.y ...

The RPi is actually a VideoCore 4 processor with an ARM co-processor. The VC4 part runs a closed source OS (TreadX, IIRC) that controls the board and then enables the ARM co-processor after booting. The ARM co-processor passes messages back and forth through a mailbox to the VC4 OS. Since the ARM part is just a co-processor, its far more trivial to port newer kernels to it.

With that in mind, we should be able to do the exact same "trick" on Odroid C2. We can boot the board with a XEN hypervisor and run a hardware accelerated VM with a mainline Linux kernel.

That is not very accurate. The VC4 firmware acts more like uboot than the linux kernel. It does some one time initialisation, like enabling sdram, starting clocks, enabling power domains to allow linux to boot, but linux runs just like on any other platform. If you are not actively using GPU features you can even crash the GPU and be completely unaware. The arm and linux will happily carry on running.

The reason the newer linux kernels run on it, is because each time a kernel revision comes out, I rebase onto it, fix merge conflicts, test it, fix any issues that have arisen, push it out to testers (e.g. Milhouse builds here, and "BRANCH-next rpi-update" for general linux users) and try to fix any issues that are reported in testing. Eventually we bump the stable kernel. The work required is by no means trivial.

If you like bleeding edge, the latest 4.5-rc4 kernel is here.

Thought so. No smoke and mirrors. No shortcuts. You're just putting the work in that other ARM platform developers aren't...