To do that, simply disable Passenger for the directory of your PHP application.
Alias /forum /var/.../forum <Location /forum> # This allows PHP. PassengerEnabled off DirectoryIndex index.php allow from all Options +Indexes </Location>
Enjoy!
Alias /forum /var/.../forum <Location /forum> # This allows PHP. PassengerEnabled off DirectoryIndex index.php allow from all Options +Indexes </Location>