diff --git a/components/dfs/src/select.c b/components/dfs/src/select.c
index c72776399159c654557acd5f3f5f957ad36249ad..cbbd159557a813b2b3636672a9cb20eff6a12904 100644
--- a/components/dfs/src/select.c
+++ b/components/dfs/src/select.c
@@ -28,6 +28,23 @@
 #include <dfs_poll.h>
 #include <dfs_select.h>
 
+static void fdszero(fd_set *set, int nfds)
+{
+    fd_mask *m;
+    int n;
+    
+    /*
+      The 'sizeof(fd_set)' of the system space may differ from user space,
+      so the actual size of the 'fd_set' is determined here with the parameter 'nfds'
+    */
+    m = (fd_mask*)set;
+    for (n = 0; n < nfds; n += (sizeof(fd_mask) * 8))
+    {
+        rt_memset(m, 0, sizeof(fd_mask));
+        m ++;
+    }
+}
+
 int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
 {
     int fd;
@@ -113,17 +130,17 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struc
     /* Now set up the return values */
     if (readfds)
     {
-        memset(readfds, 0, sizeof(fd_set));
+        fdszero(readfds, nfds);
     }
 
     if (writefds)
     {
-        memset(writefds, 0, sizeof(fd_set));
+        fdszero(writefds, nfds);
     }
 
     if (exceptfds)
     {
-        memset(exceptfds, 0, sizeof(fd_set));
+        fdszero(exceptfds, nfds);
     }
 
     /* Convert the poll descriptor list back into selects 3 bitsets */
diff --git a/components/lwp/lwp_syscall.c b/components/lwp/lwp_syscall.c
index 1b5aa411aa7264c2b3ee4b7059cd48d31084539a..0150e50b62157654627d9f7cac706924a63c0d1a 100644
--- a/components/lwp/lwp_syscall.c
+++ b/components/lwp/lwp_syscall.c
@@ -27,6 +27,8 @@
 #include <lwp_syscall.h>
 
 #include <dfs_poll.h>
+#include <dfs_select.h>
+
 #if (defined(RT_USING_SAL) && defined(SAL_USING_POSIX))
 #include <sys/socket.h>
 
@@ -235,7 +237,7 @@ const static void* func_table[] =
 
     (void *)sys_gettimeofday,   // 0x0b
     (void *)sys_settimeofday,   // 0x0c
-        
+
     (void *)sys_malloc,         // 0x0d
     (void *)sys_free,           // 0x0e
     (void *)sys_realloc,      //0x0f
@@ -256,6 +258,8 @@ const static void* func_table[] =
     SYSCALL_NET(send),       // 0x1d
     SYSCALL_NET(sendto),     // 0x1e
     SYSCALL_NET(socket),     // 0x1f
+
+    select,                  // 0x20
 };
 
 const void *lwp_get_sys_api(rt_uint32_t number)