[kenel] add static name for rt_object

include/rtdef.h

@@ -398,7 +398,11 @@ typedef struct rt_slist_node rt_slist_t;                /**< Type for single lis
  */
 struct rt_object
 {
-    char       name[RT_NAME_MAX];                       /**< name of kernel object */
+#if RT_NAME_MAX == 0
+    char      *name;                                    /**< static name of kernel object */
+#else
+    char       name[RT_NAME_MAX];                       /**< dynamic name of kernel object */
+#endif /* RT_NAME_MAX == 0 */
     rt_uint8_t type;                                    /**< type of kernel object */
     rt_uint8_t flag;                                    /**< flag of kernel object */
 
@@ -630,7 +634,11 @@ struct rt_cpu
 struct rt_thread
 {
     /* rt object */
-    char        name[RT_NAME_MAX];                      /**< the name of thread */
+#if RT_NAME_MAX == 0
+    char      *name;                                    /**< static name of kernel object */
+#else
+    char       name[RT_NAME_MAX];                       /**< dynamic name of kernel object */
+#endif /* RT_NAME_MAX == 0 */
     rt_uint8_t  type;                                   /**< type of object */
     rt_uint8_t  flags;                                  /**< thread's flags */
 

src/Kconfig

@@ -2,7 +2,7 @@ menu "RT-Thread Kernel"
 
 config RT_NAME_MAX
     int "The maximal size of kernel object name"
-    range 2 32
+    range 0 64
     default 8
     help
         Each kernel object, such as thread, timer, semaphore etc, has a name,

src/idle.c

@@ -306,13 +306,21 @@ static void rt_thread_system_entry(void *parameter)
 void rt_thread_idle_init(void)
 {
     rt_ubase_t i;
+#if RT_NAME_MAX > 0
     char idle_thread_name[RT_NAME_MAX];
+#endif /* RT_NAME_MAX > 0 */
 
     for (i = 0; i < _CPUS_NR; i++)
     {
-        rt_sprintf(idle_thread_name, "tidle%d", i);
+#if RT_NAME_MAX > 0
+        rt_snprintf(idle_thread_name, RT_NAME_MAX, "tidle%d", i);
+#endif /* RT_NAME_MAX > 0 */
         rt_thread_init(&idle_thread[i],
+#if RT_NAME_MAX > 0
                 idle_thread_name,
+#else
+                "tidle",
+#endif /* RT_NAME_MAX > 0 */
                 idle_thread_entry,
                 RT_NULL,
                 &idle_thread_stack[i][0],