diff --git a/bsp/stm32f40x/applications/application.c b/bsp/stm32f40x/applications/application.c
index 2a01107f6b24f555815c5e324d20256c1346b308..c5e5bcf296eaa405c3d9ea6e87a2ae848e3ab290 100644
--- a/bsp/stm32f40x/applications/application.c
+++ b/bsp/stm32f40x/applications/application.c
@@ -23,8 +23,18 @@
 #include "stm32_eth.h"
 #endif
 
+#ifdef RT_USING_GDB
+#include <gdb_stub.h>
+#endif
+
 void rt_init_thread_entry(void* parameter)
 {
+    /* GDB STUB */
+#ifdef RT_USING_GDB
+    gdb_set_device("uart6");
+    gdb_start();
+#endif
+
     /* LwIP Initialization */
 #ifdef RT_USING_LWIP
     {
diff --git a/bsp/stm32f40x/drivers/board.h b/bsp/stm32f40x/drivers/board.h
index 44fef35cb32631a52cb343d12d19297a68d3a81e..33b423ae1c8cad7b60941c605d2117db4f79e18f 100644
--- a/bsp/stm32f40x/drivers/board.h
+++ b/bsp/stm32f40x/drivers/board.h
@@ -43,6 +43,7 @@
 //#define RT_USING_UART1
 #define RT_USING_UART2
 //#define RT_USING_UART3
+#define RT_USING_UART6
 
 // <o> Console on USART: <0=> no console <1=>USART 1 <2=>USART 2 <3=> USART 3
 // 	<i>Default: 1
diff --git a/bsp/stm32f40x/drivers/stm32f4xx_it.c b/bsp/stm32f40x/drivers/stm32f4xx_it.c
index 69a606874602aaf64729acbd778feb56ece23a00..b7a82e33021954ea684b514506a826e30b2c358c 100644
--- a/bsp/stm32f40x/drivers/stm32f4xx_it.c
+++ b/bsp/stm32f40x/drivers/stm32f4xx_it.c
@@ -117,9 +117,10 @@ void SVC_Handler(void)
   * @param  None
   * @retval None
   */
-void DebugMon_Handler(void)
-{
-}
+//void DebugMon_Handler(void)
+//{
+    //definitio in gdb/libcpu/cortexm
+//}
 
 /**
   * @brief  This function handles PendSVC exception.
diff --git a/bsp/stm32f40x/drivers/usart.c b/bsp/stm32f40x/drivers/usart.c
index 6864a3fc92784b0459390d928609f5a8421c39db..8b87dbbb107fff31d5b25f7db338b685a1c9537b 100644
--- a/bsp/stm32f40x/drivers/usart.c
+++ b/bsp/stm32f40x/drivers/usart.c
@@ -69,6 +69,17 @@ struct stm32_serial_device uart3 =
 struct rt_device uart3_device;
 #endif
 
+#ifdef RT_USING_UART6
+struct stm32_serial_int_rx uart6_int_rx;
+struct stm32_serial_device uart6 =
+{
+    USART6,
+    &uart6_int_rx,
+    RT_NULL
+};
+struct rt_device uart6_device;
+#endif
+
 //#define USART1_DR_Base  0x40013804
 //#define USART2_DR_Base  0x40004404
 //#define USART3_DR_Base  0x40004804
@@ -103,6 +114,14 @@ struct rt_device uart3_device;
 #define UART3_TX_DMA        DMA1_Stream1
 #define UART3_RX_DMA        DMA1_Stream3
 
+#define UART6_GPIO_TX       GPIO_Pin_6
+#define UART6_TX_PIN_SOURCE GPIO_PinSource6
+#define UART6_GPIO_RX       GPIO_Pin_7
+#define UART6_RX_PIN_SOURCE GPIO_PinSource7
+#define UART6_GPIO          GPIOC
+#define UART6_GPIO_RCC      RCC_AHB1Periph_GPIOC
+#define RCC_APBPeriph_UART6 RCC_APB2Periph_USART6
+
 static void RCC_Configuration(void)
 {
 #ifdef RT_USING_UART1
@@ -128,6 +147,13 @@ static void RCC_Configuration(void)
     /* DMA clock enable */
     RCC_APB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
 #endif
+
+#ifdef RT_USING_UART6
+    /* Enable USART6 GPIO clocks */
+    RCC_AHB1PeriphClockCmd(UART6_GPIO_RCC, ENABLE);
+    /* Enable USART6 clock */
+    RCC_APB2PeriphClockCmd(RCC_APBPeriph_UART6, ENABLE);
+#endif
 }
 
 static void GPIO_Configuration(void)
@@ -168,6 +194,16 @@ static void GPIO_Configuration(void)
     GPIO_PinAFConfig(UART3_GPIO, UART3_TX_PIN_SOURCE, GPIO_AF_USART3);
     GPIO_PinAFConfig(UART3_GPIO, UART3_RX_PIN_SOURCE, GPIO_AF_USART3);
 #endif
+
+#ifdef RT_USING_UART6
+    /* Configure USART6 Rx/tx PIN */
+    GPIO_InitStructure.GPIO_Pin = UART6_GPIO_TX | UART6_GPIO_RX;
+    GPIO_Init(UART6_GPIO, &GPIO_InitStructure);
+
+    /* Connect alternate function */
+    GPIO_PinAFConfig(UART6_GPIO, UART6_TX_PIN_SOURCE, GPIO_AF_USART6);
+    GPIO_PinAFConfig(UART6_GPIO, UART6_RX_PIN_SOURCE, GPIO_AF_USART6);
+#endif
 }
 
 static void NVIC_Configuration(void)
@@ -204,6 +240,15 @@ static void NVIC_Configuration(void)
     NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
     NVIC_Init(&NVIC_InitStructure);
 #endif
+
+#ifdef RT_USING_UART6
+    /* Enable the USART6 Interrupt */
+    NVIC_InitStructure.NVIC_IRQChannel = USART6_IRQn;
+    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
+    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
+    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
+    NVIC_Init(&NVIC_InitStructure);
+#endif
 }
 
 static void DMA_Configuration(void)
@@ -346,4 +391,19 @@ void rt_hw_usart_init()
     /* enable interrupt */
     USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
 #endif
+
+#ifdef RT_USING_UART6
+    USART_InitStructure.USART_BaudRate = 9600;
+    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
+    USART_InitStructure.USART_StopBits = USART_StopBits_1;
+    USART_InitStructure.USART_Parity = USART_Parity_No;
+    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
+    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
+    USART_Init(USART6, &USART_InitStructure);
+
+    /* register uart6 */
+    rt_hw_serial_register(&uart6_device, "uart6",
+        RT_DEVICE_FLAG_RDWR | RT_DEVICE_FLAG_STREAM,
+        &uart6);
+#endif
 }
diff --git a/bsp/stm32f40x/rtconfig.h b/bsp/stm32f40x/rtconfig.h
index e961fb2e8f6af581136b57af29cb3a11df0dad04..64cc047ad83495dbdd2f7bb7f25487a3412dd846 100644
--- a/bsp/stm32f40x/rtconfig.h
+++ b/bsp/stm32f40x/rtconfig.h
@@ -2,6 +2,9 @@
 #ifndef __RTTHREAD_CFG_H__
 #define __RTTHREAD_CFG_H__
 
+/* RT_GDB_STUB */
+//#define RT_USING_GDB
+
 /* RT_NAME_MAX*/
 #define RT_NAME_MAX	   8
 
diff --git a/bsp/stm32f40x/stm32_rom.ld b/bsp/stm32f40x/stm32_rom.ld
index bd2ef9fe4487debae8a58a84b2b40a5c22c53af2..aa9c9b2af28c750ebc70720c84c1f1889ca6c949 100644
--- a/bsp/stm32f40x/stm32_rom.ld
+++ b/bsp/stm32f40x/stm32_rom.ld
@@ -10,7 +10,7 @@ MEMORY
     DATA (rw) : ORIGIN = 0x20000000, LENGTH =  128k /* 128K sram */
 }
 ENTRY(Reset_Handler)
-_system_stack_size = 0x100;
+_system_stack_size = 0x200;
 
 SECTIONS
 {