config: add enableCudaDriverCompat (#567786)

pkgs/development/cuda-modules/packages/cuda_compat.nix

@@ -1,4 +1,8 @@
-{ buildRedist }:
+{
+  buildRedist,
+  config,
+  lib,
+}:
 buildRedist {
   redistName = "cuda";
   pname = "cuda_compat";
@@ -16,5 +20,11 @@ buildRedist {
   meta = {
     description = "Provides minor version forward compatibility for the CUDA runtime";
     homepage = "https://docs.nvidia.com/deploy/cuda-compatibility";
+    problems = lib.optionalAttrs config.enableCudaDriverCompat {
+      cuda-compat-disabled = {
+        kind = "broken";
+        message = "cuda_compat must be explicitly enabled using config.enableCudaDriverCompat.";
+      };
+    };
   };
 }

pkgs/top-level/config.nix

@@ -348,6 +348,17 @@ let
       '';
     };
 
+    enableCudaDriverCompat = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Whether to enable the cuda_compat package which provides user mode backports of newer kernel
+        mode driver functionality.
+        Ony enable this if your host driver is older than the driver provided by the default
+        cudaPackages package set.
+      '';
+    };
+
     replaceBootstrapFiles = mkMassRebuild {
       type = types.functionTo (types.attrsOf types.package);
       default = lib.id;