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            Userland dependency of wpeframework and snapshot feature is removed with vc4 changes. wayland opengl is enabled for gstreamer plugins. Gstreamer packages are enabled with GLES2 and EGL libraries.

  Westeros Changes :

      Userland uses dispmanx for rendering graphics and video. With vc4graphics instead of dispmanx, DRM (Direct Rendering Manager) module is used.  DRM is a subsystem of the Linux kernel responsible for interfacing with GPUs of modern video cards. DRM is a kernel module that gives direct hardware access to DRI clients. Westeros-dispmanx is suppressed and westeros-drm is used for rendering.  Westeros-sink is enabled to use v4l2 by modifying soc-path to v4l2.  Westeros was updated to latest revision for supporting video codecs that are already used.

     Gstreamer packages are enabled with GLES2 and EGL libraries. 

List of changes done

• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39272
• https://github.com/WebPlatformForEmbedded/meta-wpe/pull/450
• https://github.com/rdkcmfagherzan/westerosmeta-raspberrypi/commit/2a284afa462656602ea15acfad3150288ed1b6dbpull/647, this pull was modified for CMF as  https://code.rdkcentral.com/r/c/rdk/components/opensource/oe/meta-raspberrypi/+/39347
• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39279

• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39287

• https://code.rdkcentral.com/r/c/components/generic/rdk-oe/meta-cmf-raspberrypi/+/39285
• https://code.rdkcentral.com/r/c/components/opensourcegeneric/rdk-oe/meta-cmf-raspberrypi/+/3934739284

 System Work Flow

           Direct Rendering Infrastructure (DRI) provide interface to interface Mesa, OpenGL and other 3D rendering API libraries with the device drivers and hardware. Mesa also contains an implementation of software rendering called swrast that allows shaders to run on the CPU as a fallback when no graphics hardware accelerators are present. The Gallium software rasterizer is known as softpipe or when built with support for LLVM llvmpipe, which generates CPU code at runtime

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•  Flashing the image

     Image is flashed to micro SD card before inserting to RPI board.   

  Command to flash the image

      Generated image has to be flashed to an micro SD card using this command in local PC:

  $ sudo dd if=<path to ImageName.rpi-sdimg> of=<path to micro SD card space> bs=4M

The micro SD card is then inserted to the Raspberry Pi board and booted to check for containers created. The Raspberry Pi board is connected to the PC via a USB to serial converter and the logs can be checked in console or can be connected via HDMI cable to a TV and logs will be shown in the terminal

References

•  http://heim.ifi.uio.no/~knuto/kernel/4.14/gpu/vc4.html?highlight=vc4
•  https://en.wikipedia.org/wiki/Free_and_open-source_graphics_device_driver
• https://en.wikipedia.org/wiki/Mesa_(computer_graphics)
• https://www.raspberrypi.org/blog/open-source-arm-userspace/
• https://en.wikipedia.org/wiki/EGL_(API)
• https://www.khronos.org/opengl/wiki/Platform_specifics:_Linux
• https://en.wikipedia.org/wiki/OpenGL
• https://elinux.org/Raspberry_Pi_VideoCore_APIs