Hello!

I am trying to launch tests that rely on CUDA, following help from Gaétan Lepage yesterday, but I do not succeed.
My host is running nixpkgs 25.05, with a clone of nixpkgs/master in the current directory.

Any idea how to get this to run?

nix-build -I nixpkgs=. --arg config '{ allowUnfree = true; cudaSupport = true;}' -A python313Packages.triton.tests.axpy-cuda.gpuCheck
this derivation will be built:
  /nix/store/2m1zkm221qr6ziw2qkbds3r37r57f7xj-test-cuda.drv
building '/nix/store/2m1zkm221qr6ziw2qkbds3r37r57f7xj-test-cuda.drv'...
Traceback (most recent call last):
  File "/nix/store/biwmrywsnh5nvfxg13d319cx65956rvc-tester-cuda/bin/tester-cuda", line 38, in <module>
    x = torch.rand(size, device='cuda')
  File "/nix/store/419qp86g5l617y4pv5m0fgj04rhfnxrp-python3-3.13.6-env/lib/python3.13/site-packages/torch/cuda/__init__.py", line 412, in _lazy_init
    torch._C._cuda_init()
    ~~~~~~~~~~~~~~~~~~~^^
RuntimeError: Found no NVIDIA driver on your system. Please check that you have an NVIDIA GPU and installed a driver from http://www.nvidia.com/Download/index.aspx
error: builder for '/nix/store/2m1zkm221qr6ziw2qkbds3r37r57f7xj-test-cuda.drv' failed with exit code 1;
       last 7 log lines:
       > Traceback (most recent call last):
       >   File "/nix/store/biwmrywsnh5nvfxg13d319cx65956rvc-tester-cuda/bin/tester-cuda", line 38, in <module>
       >     x = torch.rand(size, device='cuda')
       >   File "/nix/store/419qp86g5l617y4pv5m0fgj04rhfnxrp-python3-3.13.6-env/lib/python3.13/site-packages/torch/cuda/__init__.py", line 412, in _lazy_init
       >     torch._C._cuda_init()
       >     ~~~~~~~~~~~~~~~~~~~^^
       > RuntimeError: Found no NVIDIA driver on your system. Please check that you have an NVIDIA GPU and installed a driver from http://www.nvidia.com/Download/index.aspx
       For full logs, run:
         nix log /nix/store/2m1zkm221qr6ziw2qkbds3r37r57f7xj-test-cuda.drv

 python
Python 3.12.11 (main, Jun  3 2025, 15:41:47) [GCC 14.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import torch
>>> torch.cuda.is_available()
True

nix-shell -I nixpkgs=. --arg config '{ allowUnfree = true; cudaSupport = true;}' -p python312Packages.torch

[nix-shell:~/Repos/hoh/nixpkgs]$ python
Python 3.12.11 (main, Jun  3 2025, 15:41:47) [GCC 14.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import torch
>>> torch.cuda.is_available()
True