For SDL2 game controller support, at least SDL 2.0.4 is required.
Under the assets directory is the SDL2 game controller database: gamecontrollerdb.txt. This file contains many known control pad mappings for Windows, Linux and MAC OS. PPSSPPSDL will load this file at start-up and work out how to assign control pad buttons for your control pad.
Hot plugging of control pads is also supported.
If you control pad has a "Guide" or "Home" button then when pressed, this will trigger the emulator pause menu, thus allowing you to exit the emulator if you wish or load another game from your library.