dacbert: try enabling fscache for nfs

hosts/dacbert/default.nix

@@ -107,7 +107,7 @@ in
   fileSystems."/" = {
     device = "${hostRegistry.nfsroot.ip4}:/var/lib/nfsroot/dacbert";
     fsType = "nfs";
-    options = [ "nfsvers=3" "proto=tcp" "nolock" "hard" "async" "rw" ];
+    options = [ "nfsvers=3" "proto=tcp" "nolock" "hard" "async" "rw" "fsc" ];
   };
 
   networking = {

modules/rpi-netboot.nix

@@ -76,4 +76,10 @@
 
     echo "dwc_otg.lpm_enable=0 init=${config.system.build.toplevel}/init ${toString config.boot.kernelParams}" > $out/cmdline.txt
   '';
+
+  # NFS caching
+  services.cachefilesd = {
+    enable = true;
+    cacheDir = "/tmp/fscache";
+  };
 }