So far, It boots, running threads and such. It should be a good starting point if someone gets the hand dirty with better RTOS than what Arduino has offered.
I develop it on Windows, and build with the toolchain that Arduino uses. I suppose it works on Linux with almost no modification.
If I understand correctly, fat16lib's approach is run Chibios/RT scheduler with the Arduino Due existing Library. That said, to control the hardware register, you have to use the Arduino library (writing pins, USB, timer, etc), not the Chibios/RT.
While what I am doing is implementing the low level driver for Due on Chibios/RT. No dependency on the Arduino stack - which means instead of digitalWrite, one have to code in Chibios/RT style.