Hello, everyone, I am a beginner to learn about the linux kernel. I met the following problem today: I created a C file called "drv_event.c", and put it into the location "/lib", since I want to link it to the library of the kernel, i.e., *lib.a*. I also put the header file "drv_event.h" into the directory "/include/linux". I recompile the directory "/lib", and my own object "drv_event.o" was successfully linked into the *lib.a*. However, I called one of the functions defined in the "drv_event.c" in my driver, and I compiled this driver, at the link time, I got the warning which shows that the function called is undefined. It seems although I do recompile the lib.a successfully, but I did not put the new one into the right place. I tried "make install lib" and also "make install" in the kernel source. However, I still got the same warning at the link time. So does someone can help me to get rid of this problem? Thanks so much. Best, Li