Can't get an OpenGL context above 1.3 in Stretch

[Daniel Keast <daniel@kea.st>]

Heya All,

I have some OpenGL code that used to work fine on Jessie, but now I'm running
Stretch I can't seem to get a context above 1.3. I have a ThinkPad X220, with
cpuinfo reporting that it has an "Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz".

This I think is the relevant bit of code, but I'm happy to provide the rest,
it's just noddy glued together examples to make a cube spin:

    window = SDL_CreateWindow("SDL", SDL_WINDOWPOS_CENTERED,
                                  SDL_WINDOWPOS_CENTERED, 0, 0,
                                  SDL_WINDOW_FULLSCREEN_DESKTOP
                                      | SDL_WINDOW_OPENGL);
    if (!window) sdl_fail();

    if (SDL_ShowCursor(SDL_DISABLE) < 0) sdl_fail();

    /* initialise opengl */
    if (SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2) != 0) sdl_fail
    if (SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1) != 0) sdl_fail
    if (SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1) != 0) sdl_fail();

    if (!SDL_GL_CreateContext(window)) sdl_fail();
    glEnable(GL_DEPTH_TEST);

    {
        GLenum err = glewInit();
        if (GLEW_OK != err) {
            fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
            exit(1);
        }
    }

    printf("GL_RENDERER:\t%s\n", glGetString(GL_RENDERER));
    printf("GL_VERSION:\t%s\n", glGetString(GL_VERSION));
    printf("GL_VENDOR:\t%s\n", glGetString(GL_VENDOR));

Just running as it is, I get this output:

    $ ./glthing
    MESA-LOADER: failed to retrieve device information
    GL_RENDERER:    Mesa DRI Unknown Intel Chipset
    GL_VERSION:     1.3 Mesa 13.0.6
    GL_VENDOR:      Intel Open Source Technology Center
    Segmentation fault

The segfault is happening just below this code, when it tries to call
glBindBuffers (which isn't in OpenGL 1.3). If I request an OpenGL 3.0 context
(I think this cpu should support slightly above that) it fails when creating the
context:

    $ ./glthing
    MESA-LOADER: failed to retrieve device information

    Could not create GL context: GLXBadFBConfig

If I dont use GLEW, and just use the OpenGL headers directly (and remove
anything not OpenGL 1) then I get the higher context, this seems to match what
happens with glxgears (which from the code seems to use the immediate mode):

    $ glxgears -info 2>&1 | grep GL_ | head -n 3
    GL_RENDERER   = Mesa DRI Intel(R) Sandybridge Mobile
    GL_VERSION    = 3.0 Mesa 13.0.6
    GL_VENDOR     = Intel Open Source Technology Center

There's no mention of the MESA-LOADER line in the raw output of glxgears. Some
searching online doesn't seem to have gotten me anything useful about what that
might be caused by.

Supertuxkart reports that same GLXBadFBConfig line, and then seems to work
anyway (reporting a 3.0 context).

    $ supertuxkart --log=2 | sed -ne '/Irrlicht/,$p'
    Irrlicht Engine version 1.8.0
    Linux 4.9.0-6-amd64 #1 SMP Debian 4.9.82-1+deb9u3 (2018-03-02) x86_64
    [warn   ] [IrrDriver Temp Logger]: Level 2: X Error: GLXBadFBConfig
    [warn   ] [IrrDriver Temp Logger]: Level 2: From call : unknown
    [warn   ] [IrrDriver Temp Logger]: Level 3: Vertex shader compilation failed at position -1:
    [warn   ] [IrrDriver Temp Logger]: Level 3: Pixel shader compilation failed at position -1:
    [warn   ] [IrrDriver Temp Logger]: Level 3: Vertex shader compilation failed at position -1:
    [warn   ] [IrrDriver Temp Logger]: Level 3: Pixel shader compilation failed at position -1:
    [warn   ] [IrrDriver Temp Logger]: Level 3: Vertex shader compilation failed at position -1:
    [warn   ] [IrrDriver Temp Logger]: Level 3: Pixel shader compilation failed at position -1:
    [info   ] IrrDriver: OpenGL version: 3.3
    [info   ] IrrDriver: OpenGL vendor: Intel Open Source Technology Center
    [info   ] IrrDriver: OpenGL renderer: Mesa DRI Intel(R) Sandybridge Mobile
    [info   ] IrrDriver: OpenGL version string: 3.3 (Core Profile) Mesa 13.0.6

I don't have any Xorg.conf.d lines now, although I've tried the intel and
modesetting driver, and both sna and uxa.

Oh, also if I use the LIBGL_SOFTWARE_ALWAYS=true environment variable the code
runs perfetly fine:

    $ LIBGL_ALWAYS_SOFTWARE=true ./glthing
    GL_VERSION:     Gallium 0.4 on llvmpipe (LLVM 3.9, 256 bits)
    GL_VERSION:     3.0 Mesa 13.0.6
    GL_VERSION:     VMware, Inc.

For the complexity of things that I'm rendering right now, software is perfectly
fine... it'd just be nice to have some idea of what's going on. Any chance
anyone could shed some light on this for me?

-- 
Daniel Keast

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