diff --git a/src/clock.c b/src/clock.c
index 0b91dbcfc69afa53f16f23c2c2d9d9b6e6eedf97..4f785dd5b91579518168cdcd1eabc2f244d2dab5 100644
--- a/src/clock.c
+++ b/src/clock.c
@@ -11,13 +11,13 @@
  * Date           Author       Notes
  * 2006-03-12     Bernard      first version
  * 2006-05-27     Bernard      add support for same priority thread schedule
- * 2006-08-10     Bernard      remove the last rt_schedule in rt_tick_increase
+ * 2006-08-10     Bernard      remove the last rt_schedule in rt_tick_increase
+ * 2010-03-08     Bernard      remove rt_passed_second
  */
 
 #include <rtthread.h>
 
 static rt_tick_t rt_tick;
-static rt_time_t rt_passed_second;
 
 extern void rt_timer_check(void);
 
@@ -29,7 +29,6 @@ extern void rt_timer_check(void);
 void rt_system_tick_init()
 {
 	rt_tick = 0;
-	rt_passed_second = 0;
 }
 
 /**
@@ -60,11 +59,6 @@ void rt_tick_increase()
 	/* increase the global tick */
 	++ rt_tick;
 
-	if (rt_tick % RT_TICK_PER_SECOND == 0)
-	{
-		++rt_passed_second;
-	}
-
 	/* check timer  */
 	rt_timer_check();
 
diff --git a/src/device.c b/src/device.c
index 818f4e04455c33fba36e86037031051333443b6e..6f709e38c06d238c3ac7aaf07bbc423e3a1f6706 100644
--- a/src/device.c
+++ b/src/device.c
@@ -81,12 +81,12 @@ rt_err_t rt_device_init_all()
 			result = init(device);
 			if (result != RT_EOK)
 			{
-				rt_kprintf("To initialize device:%s failed. The error code is %d\n",
+				rt_kprintf("To initialize device:%s failed. The error code is %d\n",
 					device->parent.name, result);
-			}
-			else
-			{
-				device->flag |= RT_DEVICE_FLAG_ACTIVATED;
+			}
+			else
+			{
+				device->flag |= RT_DEVICE_FLAG_ACTIVATED;
 			}
 		}
 	}
@@ -124,6 +124,22 @@ rt_err_t rt_device_open(rt_device_t dev, rt_uint16_t oflag)
 
 	result = RT_EOK;
 
+	/* if device is not initialized, initialize it. */
+	if (!(dev->flag & RT_DEVICE_FLAG_ACTIVATED))
+	{
+		result = dev->init(dev);
+		if (result != RT_EOK)
+		{
+			rt_kprintf("To initialize device:%s failed. The error code is %d\n",
+				dev->parent.name, result);
+			return result;
+		}
+		else
+		{
+			dev->flag |= RT_DEVICE_FLAG_ACTIVATED;
+		}
+	}
+
 	/* device is a standalone device and opened */
 	if ((dev->flag & RT_DEVICE_FLAG_STANDALONE) &&
 		(dev->open_flag & RT_DEVICE_OFLAG_OPEN))
diff --git a/src/irq.c b/src/irq.c
index 3edde2f7bf10510827f5e339db7e51e7439fe449..4effde32a009228538add2daa78fc5d149150f01 100644
--- a/src/irq.c
+++ b/src/irq.c
@@ -24,7 +24,7 @@
 
 /*@{*/
 
-volatile rt_uint32_t rt_interrupt_nest;
+volatile rt_uint8_t rt_interrupt_nest;
 
 /**
  * This function will be invoked by BSP, when enter interrupt service routine
diff --git a/src/kservice.c b/src/kservice.c
index 243d00cdfc733950a4060899ae7ceb9ed12e6e67..9d9732395091a76e082a993d190fbe32e86c1024 100644
--- a/src/kservice.c
+++ b/src/kservice.c
@@ -351,7 +351,7 @@ char *rt_strlcpy(char *dest, const char *src, rt_ubase_t n)
 	while(n--)
 		*tmp++ = *s++;
 	*tmp = '\0';
-	
+
 	return dest;
 }
 
@@ -427,8 +427,6 @@ void rt_show_version()
 	rt_kprintf(" 2006 - 2009 Copyright by rt-thread team\n");
 }
 
-static char rt_log_buf[RT_CONSOLEBUF_SIZE]; /* Message log buffer */
-
 /* private function */
 #define isdigit(c)  ((unsigned)((c) - '0') < 10)
 
@@ -904,7 +902,52 @@ rt_int32_t rt_sprintf(char *buf ,const char *format,...)
 
 	return n;
 }
+
+static rt_device_t _console_device = RT_NULL;
+/**
+ * This function will set console to a device.
+ * After set a device to console, all output of rt_kprintf will be
+ * written to this device.
+ *
+ * @param device the new console device
+ *
+ * @return the old console device
+ */
+rt_device_t rt_console_set_device(const char* name)
+{
+	rt_device_t new, old;
+
+	/* save old device */
+	old = _console_device;
 
+	/* find new console device */
+	new = rt_device_find(name);
+	if (new != RT_NULL)
+	{
+		if (_console_device != RT_NULL)
+		{
+			/* close old console device */
+			rt_device_close(_console_device);
+		}
+
+		/* set new console device */
+		_console_device = new;
+		rt_device_open(_console_device, RT_DEVICE_OFLAG_RDWR);
+	}
+
+	return old;
+}
+
+#if defined(__GNUC__)
+void rt_hw_console_output(const char* str) __attribute__((weak))
+#elif defined(__CC_ARM)
+__weak void rt_hw_console_output(const char* str)
+#elif defined(__ICCARM__)
+__weak void rt_hw_console_output(const char* str)
+#endif
+{
+    /* empty console output */
+}
 
 /**
  * This function will print a formatted string on system console
@@ -914,10 +957,20 @@ rt_int32_t rt_sprintf(char *buf ,const char *format,...)
 void rt_kprintf(const char *fmt, ...)
 {
 	va_list args;
+	rt_size_t length;
+	static char rt_log_buf[RT_CONSOLEBUF_SIZE];
+
 	va_start(args, fmt);
 
-	vsnprintf(rt_log_buf, sizeof(rt_log_buf), fmt, args);
-	rt_hw_console_output(rt_log_buf);
+	length = vsnprintf(rt_log_buf, sizeof(rt_log_buf), fmt, args);
+	if (_console_device == RT_NULL)
+	{
+        rt_hw_console_output(rt_log_buf);
+	}
+	else
+	{
+		rt_device_write(_console_device, 0, rt_log_buf, length);
+	}
 
 	va_end(args);
 }