1. does opengl work ?

   $ nixGL glxgears

2. does vulkaninfo work ?


For WSL2 (nvidia GPU)

3. basic GPU access

   $ nvidia-smi

   Thu Sep 18 14:45:54 2025
   +-----------------------------------------------------------------------------------------+
   | NVIDIA-SMI 580.76.04              Driver Version: 580.97         CUDA Version: 13.0     |
   +-----------------------------------------+------------------------+----------------------+
   | GPU  Name                 Persistence-M | Bus-Id          Disp.A | Volatile Uncorr. ECC |
   | Fan  Temp   Perf          Pwr:Usage/Cap |           Memory-Usage | GPU-Util  Compute M. |
   |                                         |                        |               MIG M. |
   |=========================================+========================+======================|
   |   0  NVIDIA GeForce RTX 4070        On  |   00000000:05:00.0  On |                  N/A |
   |  0%   51C    P8             13W /  200W |    2119MiB /  12282MiB |     15%      Default |
   |                                         |                        |                  N/A |
   +-----------------------------------------+------------------------+----------------------+

   +-----------------------------------------------------------------------------------------+
   | Processes:                                                                              |
   |  GPU   GI   CI              PID   Type   Process name                        GPU Memory |
   |        ID   ID                                                               Usage      |
   |=========================================================================================|
   |  No running processes found                                                             |
   +-----------------------------------------------------------------------------------------+

   $ nixGL gxinfo | grep 'OpenGL vendor'
   OpenGL vendor string: Mesa

3a. on ubuntu

    $ cat /proc/driver/nvidia/version  # for kernel module version
    [xo-umbrella2:main :nixcpp:nxfs proj/xo-umbrella2]$ cat /proc/driver/nvidia/version
    NVRM version: NVIDIA UNIX Open Kernel Module for x86_64  580.65.06  Release Build  (dvs-builder@U22-I3-AF03-09-1)  Sun Jul 27 06:54:38 UTC 2025
    GCC version:  gcc version 13.3.0 (Ubuntu 13.3.0-6ubuntu2~24.04)

    $ nvidia-smi --version
    NVML library version: 580.95

3b. on windows11+wsl2:

   check WSL driver

   $ cat /proc/version
   Linux version 6.6.87.2-microsoft-standard-WSL2 (root@439a258ad544) (gcc (GCC) 11.2.0, GNU ld (GNU Binutils) 2.37) #1 SMP PREEMPT_DYNAMIC Thu Jun  5 18:30:46 UTC 2025

   (not sure how this helps)

4. is GLX setup?

   $ glxinfo | head -20

   $ ldd $(which glxinfo)   # will stop at libglvnd.so, though

   $ strace -e openat glxinfo 2>&1

   look for libraries that aren't found.

4a. on ubuntu

   want xo-umbrella2/etc/hostubuntu with host symlinks for:

   libEGL_nvidia, libGLX_nvidia, libGL, libGLX_indirect, libGLX_nvidia, libGLX,
   libnvidia-glcore, libnvidia-glsi, libnvidia-gpucomp, libnvidia-tls

   $ __GL_SYNC_TO_VBLANK=0 glxgears
   57207 frames in 5.0 seconds = 11441.171 FPS

5. can vulkan start?

   $ vulkaninfo --summary
   $ vkcube

5a. on ubuntu

   works, needed libnvidia-glvkspirv.so

5b. on WSL
   (fails to find .so libs, e.g. libLLVM-15.so.1)

   $ nixGLNvidia vulkaninfo

6. if something doesn't run,  try running with LD_DEBUG=libs

   LD_DEBUG=libs vkcube

or similarly

   strace -f -e trace=openat nixGL vkcube 2>&1 | grep -E "(surface|wayland|xcb|X11)"

7. Can look at exact symbol resolution

   nixGLMesa vkcube 2>&1 | grep -A5 -B5 vkGetDeviceProcAddr

8. once glxgears and vkcube run, try building + running

   xo-imgui/example/ex1    # imgui demo app, opengl
   xo-imgui/example/ex2    # imgui incremental GC demo

   [xo-umbrella2:main :nixcpp:nxfs:xo4 proj/xo-umbrella2]$  .build/xo-imgui/example/ex2/imgui_ex2
   14:23:32.933846 +(0) main
   Hello, world!
   SDL version: 2.32.56
   SDL video driver: x11
   SDL_CreateWindow done
   Requested OpenGL vtersion: 3.0
   SDL_GL_CreateContext done
   glewInit done
   OpenGL version: [4.6.0 NVIDIA 580.95.05]
   loading font [/home/roland/nixroot/nix/store/if267lm2m7q7gs1gjvlkc1i69cs3ipg9-dejavu-fonts-2.37/share/fonts/truetype/DejaVuSans.ttf]
   font loaded

9. to build vulkan examples set XO_ENABLE_VULKAN

   cmake -B .build -DCMAKE_INSTALL_PREFIX=$PREFIX -DXO_ENABLE_EXAMPLES=1 -DXO_ENABLE_VULKAN=1

   xo-imgui/example/ex3    # imgui demo app, using vulkan
   xo-imgui/example/ex4    # NOT WORKING ON UBUNTU nov 2025