Manuel
The attached patch adds support for KMS/DRM context graphics.
It builds with no problem on X86_64 GNU/Linux systems, provided the needed libraries are present, and on ARM GNU/Linux systems that have KMS/DRM support and a GLES2 implementation.
Tested on Raspberry Pi: KMS/DRM is what the Raspberry Pi will use as default in the near future, once the propietary DispmanX API by Broadcom is overtaken by open graphics stack, it's possible to boot current Raspbian system in KMS mode by adding "dtoverlay=vc4-kms-v3d" to config.txt on Raspbian's boot partition.
X86 systems use KMS right away in every current GNU/Linux system.
Simple build instructions:
$./autogen.sh
$./configure --enable-video-kmsdrm
$make
kaisyu
In case of OpenGLES, the sequences of loading and unloading driver library should be like that:
SDL_Init
...
SDL_GL_LoadLibrary
SDL_EGL_LoadLibrary
...
SDL_Quit
...
SDL_GL_UnloadLibrary
SDL_EGL_UnloadLibrary
...
However, according to my test results, the varible '_this->gl_config.driver_loaded' does not allow 'SDL_GL_UnloadLibrary' to call 'SDL_EGL_UnloadLibrary'.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
