When a P2-managed application starts, a set of configuration files are read to determine which plug-ins and features to enable. Even though files may be present in features/ and plugins/, they won't be installed into an Eclipse application unless the P2 configuration details refer to them. To understand how this works, it is informative to see how a modern Eclipse application launches and what configuration files are used.
The launcher is the eclipse executable (or Eclipse.app on Mac OS X). When run, the corresponding eclipse.ini configuration file is read. If Eclipse has been rebranded/renamed, then the executable will be called something else (notEclipse), and it will read the corresponding file (notEclipse.ini).
The launcher performs a few tasks; it shows a splash screen, creates a JVM with the arguments specified in the configuration file, and then hands over the execution to the Equinox launcher. It is also used to define an open action so that...