@hunterk ,
hi , Today i’m going in trouble ;( my new laptop just crash (motherboard)
and meanwhile , i found an old HP laptop with ubuntu 12.04 and an poor intel gm45 for videocard .
that is for the story 
So i’ve just compiled an retroarch and seems to have a pb with it :
if i just load with : retroarch -v --menu or
with core that need SET_PIXEL_FORMAT: RGB565
always faced to :
RetroArch [ERROR] :: GL: Invalid value.
RetroArch [ERROR] :: Cannot open video driver … Exiting …
RetroArch [ERROR] :: Fatal error received in: “init_video_input()”
RetroArch: Environ SET_PIXEL_FORMAT: RGB565.
RetroArch: Version of libretro API: 1
RetroArch: Compiled against API: 1
RetroArch: Set audio input rate to: 29975.00 Hz.
RetroArch: Video @ 960x720
RetroArch: Found GL context: glx
RetroArch: Detecting screen resolution 1280x1024.
RetroArch: [GLX]: X = 0, Y = 0, W = 960, H = 720.
RetroArch: [GLX]: Found swap function: glXSwapIntervalMESA.
RetroArch: [GLX]: glXSwapInterval(1)
RetroArch: [GL]: Vendor: Tungsten Graphics, Inc, Renderer: Mesa DRI Mobile Intel® GM45 Express Chipset .
RetroArch: [GL]: Version: 2.1 Mesa 8.0.2.
RetroArch: Querying GL extension: ARB_ES2_compatibility => exists
RetroArch: Querying GL extension: ARB_sync => exists
RetroArch: Querying GL extension: ARB_texture_float => exists
RetroArch: GL: Using resolution 960x720
RetroArch: [GL]: Not loading any shader.
RetroArch: GL: Using 4 textures.
RetroArch: GL: Loaded 0 program(s).
RetroArch: [GL]: Using GL_RGB565 for texture uploads.
RetroArch: [Joypad]: Found pad: ST LIS3LV02DL Accelerometer on /dev/input/js0.
RetroArch: Found joypad driver: "linuxraw".
RetroArch: Using font rendering backend: freetype.
RetroArch [ERROR] :: GL: Invalid value.
RetroArch [ERROR] :: Cannot open video driver ... Exiting ...
RetroArch [ERROR] :: Fatal error received in: "init_video_input()"
But if i load a core which use SET_PIXEL_FORMAT: XRGB8888
it load fine .
RetroArch: Version of libretro API: 1
RetroArch: Compiled against API: 1
RetroArch: Environ PERFORMANCE_LEVEL: 3.
RetroArch: ROM loading skipped. Implementation will load it on its own.
RetroArch: Environ SET_PIXEL_FORMAT: XRGB8888.
RetroArch: Set audio input rate to: 23980.00 Hz.
RetroArch: Video @ 960x720
RetroArch: Found GL context: glx
RetroArch: Detecting screen resolution 1280x1024.
RetroArch: [GLX]: X = 0, Y = 0, W = 960, H = 720.
RetroArch: [GLX]: Found swap function: glXSwapIntervalMESA.
RetroArch: [GLX]: glXSwapInterval(1)
RetroArch: [GL]: Vendor: Tungsten Graphics, Inc, Renderer: Mesa DRI Mobile Intel® GM45 Express Chipset .
RetroArch: [GL]: Version: 2.1 Mesa 8.0.2.
RetroArch: Querying GL extension: ARB_ES2_compatibility => exists
RetroArch: Querying GL extension: ARB_sync => exists
RetroArch: Querying GL extension: ARB_texture_float => exists
RetroArch: GL: Using resolution 960x720
RetroArch: [GL]: Not loading any shader.
RetroArch: GL: Using 4 textures.
RetroArch: GL: Loaded 0 program(s).
RetroArch: [Joypad]: Found pad: ST LIS3LV02DL Accelerometer on /dev/input/js0.
RetroArch: Found joypad driver: "linuxraw".
RetroArch: Using font rendering backend: freetype.
RetroArch: Suspending screensaver (X11).
RetroArch: ALSA: Using signed 16-bit format.
RetroArch: ALSA: Period size: 768 frames
RetroArch: ALSA: Buffer size: 3072 frames
RetroArch: ALSA: Can pause: yes.
RetroArch: Sinc resampler [SSE]
RetroArch: SINC params (8 phase bits, 16 taps).
So if you have any clue , to how get it working with rgb565 , i’ll appreciate a lot