What’s the CONFIG_OF in linux?

I see that it is being widely used at many places but could not understand in what scenarios I need to use it.

1. What is CONFIG_OF?
2. What is the full name of “OF”?

Answer

Open Firmware. This was invented long time ago when Apple was producing laptops based on PowerPC CPUs and Sun Microsystems workstations were still popular. Open Firmware provides a good description of the devices connected to the platform. In Linux kernel the part that works with device data is called Device Tree (DT). More details in the Usage model.