anchor.diff:            '';
         };
   
  +    virtualisation.efiVars =
  +      mkOption {
  +        default = "./${vmName}-efi-vars.fd";
  +        description =
  +          ''
  +            Path to nvram image containing UEFI variables.  The will be created
  +            on startup if it does not exist.
  +          '';
  +      };
  +
       virtualisation.bios =
         mkOption {
           default = null;
  
positive.code:               diskImage=$out/disk.img
                ${qemu}/bin/qemu-img create -f qcow2 $diskImage "60M"
                ${if cfg.useEFIBoot then ''
                  efiVars=$out/EFI_VARS.fd
                  cp ${efiVars} $efiVars
                  chmod 0644 $efiVars
                '' else ''
                ''}
  
negative.code:       ])
        (mkIf cfg.useEFIBoot [
          "-drive if=pflash,format=raw,unit=0,readonly,file=${efiFirmware}"
          "-drive if=pflash,format=raw,unit=1,file=$NIX_EFI_VARS"
        ])
        (mkIf (cfg.bios != null) [
          "-bios ${cfg.bios}/bios.bin"
  