I have posted this question before and my problem is not totally solved because I am not familiar with Makefile. I try to make my question more specific as follows.

I want to add new code, which is already organized under a directory, say, test. I want to add the directory test to main.c file for ARM VMM, located at ~/projects/vm/apps/vm/components/VM/src/main.c. In the program, we want to refer to the sub-directories by relative path to the directory test. what is the easy to do that? How can we add the directory test  to the search path so that we can include the header files by the relative path to the directory test, say include "test1/test1.h"? 

We tried to modify the makefile at  ~projects/vm/apps/vm, but we have to add all the sub-directories, and there are problems for the files with the same name under different directories. 

thanks

Peng