Complex sentence: The ports tree uses a set of standard makefiles, some of which are shared with the source tree, to provide the bulk of its functionality; this shared infrastructure includes many utility functions for port developers and means that ports can often be made very simply.
Split into simpler sentences: The ports tree uses a set of standard makefiles, some of which are shared with the source tree, to provide the bulk of its functionality. This shared infrastructure includes many utility functions for port developers and means that ports can often be made very simply.