+#define VHOST_USER_POLLING_MODE 0
+#define VHOST_USER_INTERRUPT_MODE 1
+#define VHOST_USER_ADAPTIVE_MODE 2
+
+static u8 *
+api_format_vhost_user_operation_mode (u8 * s, va_list * va)
+{
+ int operation_mode = va_arg (*va, int);
+
+ switch (operation_mode)
+ {
+ case VHOST_USER_POLLING_MODE:
+ s = format (s, "%-9s", "polling");
+ break;
+ case VHOST_USER_INTERRUPT_MODE:
+ s = format (s, "%-9s", "interrupt");
+ break;
+ default:
+ s = format (s, "%-9s", "invalid");
+ }
+ return s;
+}
+
+static uword
+api_unformat_vhost_user_operation_mode (unformat_input_t * input,
+ va_list * args)
+{
+ u8 *operation_mode = va_arg (*args, u8 *);
+ uword rc = 1;
+
+ if (unformat (input, "interrupt"))
+ *operation_mode = VHOST_USER_INTERRUPT_MODE;
+ else if (unformat (input, "polling"))
+ *operation_mode = VHOST_USER_POLLING_MODE;
+ else
+ rc = 0;
+
+ return rc;
+}
+