eal: add application usage hook

Signed-off-by: Intel

app/test/test_debug.c

@@ -138,6 +138,26 @@ test_exit(void)
 
 #endif
 
+static void
+dummy_app_usage(const char *progname)
+{
+	RTE_SET_USED(progname);
+}
+
+static int
+test_usage(void)
+{
+	if (rte_set_application_usage_hook(dummy_app_usage) != NULL) {
+		printf("Non-NULL value returned for initial usage hook\n");
+		return -1;
+	}
+	if (rte_set_application_usage_hook(NULL) != dummy_app_usage) {
+		printf("Incorrect value returned for application usage hook\n");
+		return -1;
+	}
+	return 0;
+}
+
 int
 test_debug(void)
 {
@@ -147,5 +167,7 @@ test_debug(void)
 		return -1;
 	if (test_exit() < 0)
 		return -1;
+	if (test_usage() < 0)
+		return -1;
 	return 0;
 }

lib/librte_eal/common/include/rte_eal.h

@@ -146,6 +146,37 @@ enum rte_proc_type_t rte_eal_process_type(void);
  *   - On failure, a negative error value.
  */
 int rte_eal_init(int argc, char **argv);
+/**
+ * Usage function typedef used by the application usage function.
+ *
+ * Use this function typedef to define and call rte_set_applcation_usage_hook()
+ * routine.
+ */
+typedef void	(*rte_usage_hook_t)(const char * prgname);
+
+/**
+ * Add application usage routine callout from the eal_usage() routine.
+ *
+ * This function allows the application to include its usage message
+ * in the EAL system usage message. The routine rte_set_application_usage_hook()
+ * needs to be called before the rte_eal_init() routine in the application.
+ *
+ * This routine is optional for the application and will behave as if the set
+ * routine was never called as the default behavior.
+ *
+ * @param func
+ *   The func argument is a function pointer to the application usage routine.
+ *   Called function is defined using rte_usage_hook_t typedef, which is of
+ *   the form void rte_usage_func(const char * prgname).
+ *
+ *   Calling this routine with a NULL value will reset the usage hook routine and
+ *   return the current value, which could be NULL.
+ * @return
+ *   - Returns the current value of the rte_application_usage pointer to allow
+ *     the caller to daisy chain the usage routines if needing more then one.
+ */
+rte_usage_hook_t
+rte_set_application_usage_hook( rte_usage_hook_t usage_func );
 
 /**
  * macro to get the lock of tailq in mem_config 

lib/librte_eal/linuxapp/eal/eal.c

@@ -103,6 +103,8 @@
 	(in) = end + 1;                                         \
 }
 
+/* Allow the application to print its usage message too if set */
+static rte_usage_hook_t	rte_application_usage_hook = NULL;
 /* early configuration structure, when memory config is not mmapped */
 static struct rte_mem_config early_mem_config;
 
@@ -329,6 +331,24 @@ eal_usage(const char *prgname)
 	       "  --"OPT_NO_HPET"  : disable hpet\n"
 	       "  --"OPT_NO_SHCONF": no shared config (mmap'd files)\n\n",
 	       prgname);
+	/* Allow the application to print its usage message too if hook is set */
+	if ( rte_application_usage_hook ) {
+		printf("===== Application Usage =====\n\n");
+		rte_application_usage_hook(prgname);
+	}
+}
+
+/* Set a per-application usage message */
+rte_usage_hook_t
+rte_set_application_usage_hook( rte_usage_hook_t usage_func )
+{
+	rte_usage_hook_t	old_func;
+
+	/* Will be NULL on the first call to denote the last usage routine. */
+	old_func					= rte_application_usage_hook;
+	rte_application_usage_hook	= usage_func;
+
+	return old_func;
 }
 
 /*