Like many recent boards, the $9 C.H.I.P computer supports add-on boards, which can be dynamically discovered through a 1-Wire bus. The Device Tree overlay mechanism allows to to modify the device tree on-the-fly with dynamically loaded data. We have chosen to use this feature to configure the C.H.I.P. external capes at boot time.
This talk will describe how Device Tree overlays work and how they are generated, walk through the design of the cape manager used on the C.H.I.P and detail how a cape is detected and the Device Tree overlays applied at run-time.