anchor.diff:          ";
         };
   
  +      chrootDirs = mkOption {
  +        default = [];
  +	example = [ "/dev" "/proc" ];
  +	description =
  +	  ''
  +	    Directories from the host filesystem to be included
  +	    in the chroot.
  +	  '';
  +      };
  +
         extraOptions = mkOption {
           default = "";
           example = "
  
positive.code:                 build-users-group = nixbld
                  build-max-jobs = ${toString (config.nix.maxJobs)}
                  build-use-chroot = ${if config.nix.useChroot then "true" else "false"}
                  build-chroot-dirs = /dev /dev/pts /proc /bin $(echo $extraPaths) ${builtins.toString config.nix.extraChrootPaths}
                  $extraOptions
                  END
                '';
  
negative.code:   ###### implementation
  
    config = {
  
      nix.chrootDirs = [ "/dev" "/dev/pts" "/proc" "/bin" ];
  
      environment.etc =
        [ { # Nix configuration.
  