I'm trying to write an API as a kernel module and hope to be able to call functions from my module in device drivers. These are the steps I have followed. Am I missing anything? 1.) Write module with some functions (code.h and code.c). 2.) Build module, load with insmod. 3.) Copy code.h into <kernel>/include/linux directory. 4.) #include <linux/code.h> in a driver. 5.) Add a call to a function from my API in the driver. 6.) Build the driver, load with insmod. But this isn't working. When I try to build the driver, I get warnings saying that the API functions are undefined. Any idea what's going on?