Init Functions
The init.h header defines a mechanism to register code to run during boot.
Blocks of code (initializers) can be registered to run during boot with the DEFINE_INIT macro.
This macro takes a priority as well. Initializers are run from the lowest priority to highest. If two initializers have the same priority, they may be run in any order.
Priorities
INIT_REGISTER_DRIVERS: The priority level at which drivers should register themselves.