anchor.diff:          mkOption {
             type = types.listOf (types.submodule driveOpts);
             description = "Drives passed to qemu.";
  +          apply = addDeviceNames;
           };
   
         diskInterface =
  
positive.code:       "/dev/sd${letter}"
      else
        "/dev/vd${letter}";
  
    # Shell script to start the VM.
    startVM =
  
negative.code:           };
        } // optionalAttrs cfg.useBootLoader
        { "/boot" =
            { device = "${lookupDriveDeviceName "boot" cfg.qemu.drives}2";
              fsType = "vfat";
              options = [ "ro" ];
              noCheck = true; # fsck fails on a r/o filesystem
  