config.cudaSupport: init option

doc/languages-frameworks/cuda.section.md

@@ -13,7 +13,7 @@ compatible are available as well. For example, there can be a
 To use one or more CUDA packages in an expression, give the expression a `cudaPackages` parameter, and in case CUDA is optional
 ```nix
 { config
-, cudaSupport ? config.cudaSupport or false
+, cudaSupport ? config.cudaSupport
 , cudaPackages ? { }
 , ...
 }:

pkgs/top-level/config.nix

@@ -117,6 +117,12 @@ let
       '';
     };
 
+    cudaSupport = mkMassRebuild {
+      type = types.bool;
+      default = false;
+      feature = "build packages with CUDA support by default";
+    };
+
     showDerivationWarnings = mkOption {
       type = types.listOf (types.enum [ "maintainerless" ]);
       default = [];