View source for PROJECT HOME

 PROJECT_HOME = &lt;Root Directory&gt;

When a project consists of several directories this variable needs to be set in subdirectories so that they can all create and access intermediate build results.  Otherwise individual Makefiles do not know  about anything outside of the directory where they reside.  The variable may also be set by the Makefile in the root directory, but it is not required.

The PROJECT_HOME variable needs to be set to an absolute path, but it is bad practice to code absolute paths.  In nearly every case you will want to code this setting using this format:

 PROJECT_HOME = $(realpath ../)

The number of <code>../</code> components should be the number of level up from the subdirectory to the root directory.