Great job snesfan Out of ignorance I wanted to ask, if you port Opendingux to the rs97, will it be the same for the papk3p apart from the lcd and the controls? Is it possible a unified firmware for these machines?
Assuming everything on the board is identical minus just the LCD resolution and inputs, it should be fairly easy to make board files for buildroot. They can share most of the same rootfs. (Think a laptop and desktop can run the same distro of linux, same architecture but different components, same libraries and mostly same binaries) I'm using kernel headers for 4.x kernel so you probably don't want to try and link into it from the 2.6 kernel that comes on the papk3p.
So the kernel will likely need a bit more work to get to run. The kernel will need a branch of the config solely because of the LCD differences, and maybe ram chip(dont know the full extent of the differences) but can share a good majority of code because of its simularities.
The uboot might not need changed as long as you load the kernel to the correct memory address the current uboot is pointing. I will be making a device tree for the 4.x kernel and latest uboot for the rs97, I don't know how a bootloader without a device tree interacts with a kernel that uses one. The books and stuff I'm reading assumes you are doing both with device tree and sharing files between bootloader and kernel source.
I will assist anyone wanting to port what I come up with to the papk3p or any other device once I have something to release on the rs97. I plan on documenting the entire out of box to working OS stack process so it should be simple enough for someone with moderate programming skills and a desire to tinker. (Because that's where I'm at
info is just scattered everywhere)