ChoosePixelFormat() in wingdi.h returns system error 203 ERROR_ENVVAR_NOT_FOUND when using any software back-end.

[tfinnegan937]

I am using mesa-dist-win version 24.2.7 on Windows version 9045.5131.

I am attempting to use llvmpipe for our application under single-threaded rendering.

The following call:

    int32_t pixelFormat;
    static PIXELFORMATDESCRIPTOR pfd =
    {
        sizeof(PIXELFORMATDESCRIPTOR),              // Size of this pixel format descriptor
        1,                                          // Version number
        PFD_DRAW_TO_WINDOW |                        // Format must support window
        PFD_SUPPORT_OPENGL |                        // Format must support OpenGL
        PFD_DOUBLEBUFFER,                           // Must support double buffering
        PFD_TYPE_RGBA,                              // Request an RGBA format
        32,                                         // Select our color depth
        0, 0, 0, 0, 0, 0,                           // Color bits ignored
        0,                                          // No alpha buffer
        0,                                          // Shift bit ignored
        0,                                          // No accumulation buffer
        0, 0, 0, 0,                                 // Accumulation bits ignored
        24,                                         // 32 Bit z-buffer (depth buffer)
        8,                                          // Stencil buffer
        0,                                          // No auxiliary buffer
        PFD_MAIN_PLANE,                             // Main drawing layer
        0,                                          // Reserved
        0, 0, 0                                     // Layer masks ignored
    };

    pixelFormat = ChoosePixelFormat(hdc, &pfd);

returns 0, with error 203 being the output from GetLastError().

This occurs under the the following environment variable configurations:

1. GALLIUM_DRIVER=llvmpipe;LP_NUM_THREADS=1;
2. GALLIUM_DRIVER=softpipe;
3. GALLIUM_DRIVER=zink;LIBGL_ALWAYS_SOFTWARE=1

It does NOT occur with none of these variables set. This is a system with an RTX 3070 GPU.

Furthermore, if I replace PFD_DRAW_TO_WINDOW with PFD_DRAW_TO_BITMAP, I believe I run into a driver error. ChoosePixelForma() still returns 0, but no system error is generated with GetLastError().

[pal1000]

This issue is more suitable for upstream support.