diff --git a/include/nuttx/sched.h b/include/nuttx/sched.h
index 9c15efaf603..2d8395e0b02 100644
--- a/include/nuttx/sched.h
+++ b/include/nuttx/sched.h
@@ -781,11 +781,13 @@ begin_packed_struct struct tcbinfo_s
    * value 0: This regsiter was not priovided by NuttX
    */
 
+  begin_packed_struct
   union
   {
     uint8_t             u[8];
     FAR const uint16_t *p;
-  } reg_off;
+  }
+  end_packed_struct reg_off;
 } end_packed_struct;
 #endif
 
diff --git a/tools/.gitignore b/tools/.gitignore
index abded4c6ce9..6d6b124ab86 100644
--- a/tools/.gitignore
+++ b/tools/.gitignore
@@ -19,3 +19,4 @@
 /incdir
 /.k2h-body.dat
 /.k2h-apndx.dat
+/jlink-nuttx.so
diff --git a/tools/jlink-nuttx.c b/tools/jlink-nuttx.c
index b7597dfad7f..11ecc76c7bb 100644
--- a/tools/jlink-nuttx.c
+++ b/tools/jlink-nuttx.c
@@ -59,6 +59,25 @@
 #define PERROR                    g_plugin_priv.jops->erroroutf
 #define PLOG                      g_plugin_priv.jops->logoutf
 
+/* GCC specific definitions */
+
+#ifdef __GNUC__
+
+/* The packed attribute informs GCC that the structure elements are packed,
+ * ignoring other alignment rules.
+ */
+
+#  define begin_packed_struct
+#  define end_packed_struct __attribute__ ((packed))
+
+#else
+
+#  warning "Unsupported compiler"
+#  define begin_packed_struct
+#  define end_packed_struct
+
+#endif
+
 /****************************************************************************
  * Private Types
  ****************************************************************************/
@@ -72,20 +91,22 @@ enum symbol_e
   NSYMBOLS
 };
 
-__attribute__ ((packed)) struct tcbinfo_s
+begin_packed_struct struct tcbinfo_s
 {
   uint16_t pid_off;
   uint16_t state_off;
   uint16_t pri_off;
   uint16_t name_off;
   uint16_t reg_num;
+  begin_packed_struct
   union
   {
     uint8_t  u[8];
     uint16_t *p;
-  } reg_off;
+  }
+  end_packed_struct reg_off;
   uint16_t reg_offs[0];
-};
+} end_packed_struct;
 
 struct symbols_s
 {
diff --git a/tools/nxstyle.c b/tools/nxstyle.c
index f22a55a9c89..846780ea221 100644
--- a/tools/nxstyle.c
+++ b/tools/nxstyle.c
@@ -324,6 +324,24 @@ static const char *g_white_list[] =
   "__asan_loadN_noabort",
   "__asan_storeN_noabort",
 
+  /* Ref:
+   * tools/jlink-nuttx.c
+   */
+
+  "RTOS_Init",
+  "RTOS_GetVersion",
+  "RTOS_GetSymbols",
+  "RTOS_GetNumThreads",
+  "RTOS_GetCurrentThreadId",
+  "RTOS_GetThreadId",
+  "RTOS_GetThreadDisplay",
+  "RTOS_GetThreadReg",
+  "RTOS_GetThreadRegList",
+  "RTOS_GetThreadRegList",
+  "RTOS_SetThreadReg",
+  "RTOS_SetThreadRegList",
+  "RTOS_UpdateThreads",
+
   NULL
 };