Add a build for the yubikey management raspberry pi image.

nix/yubipi/roles/optimized_build/default.nix

@@ -0,0 +1,78 @@
+{
+  config,
+  lib,
+  pkgs,
+  pkgs-unoptimized,
+  ...
+}:
+
+{
+  imports = [ ];
+
+  options.me = {
+    optimizations.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = "Whether we want to enable CPU optimizations (will trigger a rebuild from source).";
+    };
+
+    optimizations.arch = lib.mkOption {
+      type = lib.types.str;
+      default = null;
+      example = "znver4";
+      description = "The CPU arch for which programs should be optimized.";
+    };
+
+    optimizations.system_features = lib.mkOption {
+      type = lib.types.listOf lib.types.str;
+      default = [ ];
+      example = [
+        "gccarch-armv6l"
+        "benchmark"
+        "big-parallel"
+        "kvm"
+        "nixos-test"
+      ];
+      description = "The list of CPU features that should be enabled on this machine.";
+    };
+  };
+
+  config = lib.mkMerge [
+    (lib.mkIf (!config.me.optimizations.enable) (
+      lib.mkMerge [
+        {
+        }
+      ]
+    ))
+    (lib.mkIf config.me.optimizations.enable (
+      lib.mkMerge [
+        {
+          nixpkgs.config.allowUnsupportedSystem = true;
+
+          nixpkgs.hostPlatform = {
+            gcc.arch = config.me.optimizations.arch;
+            gcc.tune = config.me.optimizations.arch;
+            system = "armv6l-linux";
+          };
+
+          # Uncomment on of these to enable cross compiling:
+          # nixpkgs.buildPlatform = builtins.currentSystem;
+          # nixpkgs.buildPlatform = {
+          #   gcc.arch = "znver4";
+          #   gcc.tune = "znver4";
+          #   system = "x86_64-linux";
+          # };
+        }
+      ]
+    ))
+    (lib.mkIf (config.me.optimizations.system_features != [ ]) (
+      lib.mkMerge [
+        {
+          nix.settings.system-features = lib.mkForce config.me.optimizations.system_features;
+        }
+      ]
+    ))
+
+  ];
+}