Can't create environment with Cuda available for pytorch

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1

I’m trying to create nix-shell with pytorch setup. Here is my shell.nix:

{ pkgs ? import <nixpkgs> {
  config = {
    allowUnfree = true;
    cudaSupport = true;
  };
} }:
  pkgs.mkShell {
    # nativeBuildInputs is usually what you want -- tools you need to run
    nativeBuildInputs = with pkgs.buildPackages; [
      python311
      cudaPackages_12.cudatoolkit
      python311Packages.pytorch-bin
      python311Packages.pip
    ];

    shellHook = ''
      echo "You are now using a NIX environment"
      export CUDA_PATH=${pkgs.cudatoolkit}
    '';
}

but after setup I have this warning:

>>> import torch
>>> torch.cuda.is_available()
/nix/store/xyzf6xd9myyr7wih6w3h43zxjps6jxk0-python3.11-torch-2.3.0/lib/python3.11/site-packages/torch/cuda/__init__.py:118: UserWarning: CUDA initialization: CUDA unknown error - this may be due to an incorrectly set up environment, e.g. changing env variable CUDA_VISIBLE_DEVICES after program start. Setting the available devices to be zero. (Triggered internally at ../c10/cuda/CUDAFunctions.cpp:108.)
  return torch._C._cuda_getDeviceCount() > 0
False
>>>

I’m new in NixOS and can’t figure out how to fix this

2

I have figured it out! My RTX 4070 is probably unsupported with nvidia open drivers. So I need to set hardware.nvidia.open = false; and everything is fine now. Here is part of my /etc/nixos/configuration.nix in case somebody need it to reproduce:

    # Graphics Drivers ###########################
    # Enable OpenGL
  hardware.opengl = {
    enable = true;
    driSupport = true;
    driSupport32Bit = true;
  };

  # Load nvidia driver for Xorg and Wayland
  services.xserver.videoDrivers = ["nvidia"];

  hardware.nvidia = {

    # Modesetting is required.
    modesetting.enable = true;

    # Nvidia power management. Experimental, and can cause sleep/suspend to fail.
    powerManagement.enable = false;
    # Fine-grained power management. Turns off GPU when not in use.
    # Experimental and only works on modern Nvidia GPUs (Turing or newer).
    powerManagement.finegrained = false;

    # Use the NVidia open source kernel module (not to be confused with the
    # independent third-party "nouveau" open source driver).
    # Support is limited to the Turing and later architectures. Full list of
    # supported GPUs is at:
    # https://github.com/NVIDIA/open-gpu-kernel-modules#compatible-gpus
    # Only available from driver 515.43.04+
    # Do not disable this unless your GPU is unsupported or if you have a good reason to.
    open = false;

    # Enable the Nvidia settings menu,
        # accessible via `nvidia-settings`.
    nvidiaSettings = true;

    # Optionally, you may need to select the appropriate driver version for your specific GPU.
    package = config.boot.kernelPackages.nvidiaPackages.stable;

  };

  ## Graphics END #############################################
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