diff --git a/arch/sim/src/up_devconsole.c b/arch/sim/src/up_devconsole.c
index 31c4e46c60..1bb0debdd4 100644
--- a/arch/sim/src/up_devconsole.c
+++ b/arch/sim/src/up_devconsole.c
@@ -33,9 +33,9 @@
  *
  ************************************************************/
 
-#ifndef linux
+#if !defined(linux) && !defined(__CYGWIN__)
 # error "Sorry, this will only work with Linux"
-#endif
+#else
 
 /************************************************************
  * Included Files
@@ -138,3 +138,6 @@ int up_putc(int ch)
   (void)up_write(1, &b, 1);
   return ch;
 }
+
+#endif /* linux */
+
diff --git a/arch/sim/src/up_idle.c b/arch/sim/src/up_idle.c
index 01457962e6..5735540e16 100644
--- a/arch/sim/src/up_idle.c
+++ b/arch/sim/src/up_idle.c
@@ -83,7 +83,7 @@ void up_idle(void)
 
   /* Run the network if enabled */
 
-#ifdef CONFIG_NET
+#if defined(CONFIG_NET) && defined(linux)
   uipdriver_loop();
 #endif
 }
diff --git a/arch/sim/src/up_initialize.c b/arch/sim/src/up_initialize.c
index a7faa50329..82ba215d85 100644
--- a/arch/sim/src/up_initialize.c
+++ b/arch/sim/src/up_initialize.c
@@ -86,7 +86,7 @@ void up_initialize(void)
   devnull_register();       /* Standard /dev/null */
   up_devconsole();          /* Our private /dev/console */
   up_registerblockdevice(); /* Our simulated block device /dev/blkdev */
-#ifdef CONFIG_NET
+#if defined(CONFIG_NET) && defined(linux)
   uipdriver_init();         /* Our "real" netwok driver */
 #endif
 }
diff --git a/arch/sim/src/up_internal.h b/arch/sim/src/up_internal.h
index de83173d18..1d08f83817 100644
--- a/arch/sim/src/up_internal.h
+++ b/arch/sim/src/up_internal.h
@@ -118,7 +118,7 @@ extern void tapdev_send(char *buf, unsigned int buflen);
 
 /* up_uipdriver.c *********************************************************/
 
-#ifdef CONFIG_NET 
+#if defined(CONFIG_NET) && defined(linux)
 extern int uipdriver_init(void);
 extern void uipdriver_loop(void);
 #endif
diff --git a/arch/sim/src/up_setjmp.S b/arch/sim/src/up_setjmp.S
index 96b9bfee88..31b9e56c0f 100644
--- a/arch/sim/src/up_setjmp.S
+++ b/arch/sim/src/up_setjmp.S
@@ -1,129 +1,5 @@
-/**************************************************************************
- * up_setjmp.S
- *
- *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- * 3. Neither the name Gregory Nutt nor the names of its contributors may be
- *    used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- **************************************************************************/
-
-/**************************************************************************
- * Conditional Compilation Options
- **************************************************************************/
-
-/**************************************************************************
- * Included Files
- **************************************************************************/
-
-#include "up_internal.h"
-
-/**************************************************************************
- * Private Definitions
- **************************************************************************/
-
-/**************************************************************************
- * Private Types
- **************************************************************************/
-
-/**************************************************************************
- * Private Function Prototypes
- **************************************************************************/
-
-/**************************************************************************
- * Global Variables
- **************************************************************************/
-
-/**************************************************************************
- * Private Variables
- **************************************************************************/
-
-/**************************************************************************
- * Private Functions
- **************************************************************************/
-
-/**************************************************************************
- * Public Functions
- **************************************************************************/
-
-	.text
-	.globl	up_setjmp
-	.type	up_setjmp, @function
-up_setjmp:
-
-	/* %ebx, %esi, %edi, and %ebp must be preserved.
-	 * save %ebx, $esi, and %edi now... */
-
-        movl	4(%esp), %eax
-        movl	%ebx, (JB_EBX)(%eax)
-        movl	%esi, (JB_ESI)(%eax)
-        movl	%edi, (JB_EDI)(%eax)
-
-        /* Save the value of SP as will be after we return */
-
-        leal	4(%esp), %ecx
-        movl	%ecx, (JB_SP)(%eax)
-
-        /* Save the return PC */
-
-        movl	0(%esp), %ecx
-        movl	%ecx, (JB_PC)(%eax)
-
-        /* Save the framepointer */
-
-        movl %ebp, (JB_EBP)(%eax)
-
-	/* And return 0 */
-
-	xorl    %eax, %eax
-        ret
-	.size	up_setjmp, . - up_setjmp
-
-	.globl	up_longjmp
-	.type	up_longjmp, @function
-up_longjmp:
-        movl	4(%esp), %ecx      /* U_pthread_jmpbuf in %ecx.  */
-        movl	8(%esp), %eax      /* Second argument is return value.  */
-
-        /* Save the return address now.  */
-
-        movl (JB_PC)(%ecx), %edx
-
-        /* Restore registers.  */
-
-        movl (JB_EBX)(%ecx), %ebx
-        movl (JB_ESI)(%ecx), %esi
-        movl (JB_EDI)(%ecx), %edi
-        movl (JB_EBP)(%ecx), %ebp
-        movl (JB_SP)(%ecx), %esp
-
-        /* Jump to saved PC.  */
-
-        jmp *%edx
-	.size up_longjmp, . - up_longjmp
-
+# 1 "up_setjmp.S"
+# 1 "/home/Owner/projects/nuttx/arch/sim/src//"
+# 1 "<built-in>"
+# 1 "<command line>"
+# 1 "up_setjmp.S"
diff --git a/arch/sim/src/up_tapdev.c b/arch/sim/src/up_tapdev.c
index f742afeac8..bf9d9db81a 100644
--- a/arch/sim/src/up_tapdev.c
+++ b/arch/sim/src/up_tapdev.c
@@ -38,9 +38,7 @@
  *
  ****************************************************************************/
 
-#ifndef linux
-# error "Sorry, this will only work with Linux"
-#endif
+#ifdef linux
 
 /****************************************************************************
  * Included Files
@@ -281,3 +279,6 @@ void tapdev_send(char *buf, unsigned int buflen)
     }
 }
 
+#endif /* linux */
+
+
diff --git a/arch/sim/src/up_uipdriver.c b/arch/sim/src/up_uipdriver.c
index 8783634b57..b49e772e01 100644
--- a/arch/sim/src/up_uipdriver.c
+++ b/arch/sim/src/up_uipdriver.c
@@ -38,6 +38,8 @@
  *
  ****************************************************************************/
 
+#ifdef linux
+
 /****************************************************************************
  * Included Files
  ****************************************************************************/
@@ -202,3 +204,6 @@ int uipdriver_init(void)
   (void)netdev_register(&g_sim_dev);
   return OK;
 }
+
+#endif /* linux */
+
diff --git a/include/nuttx/compiler.h b/include/nuttx/compiler.h
index 2b7a967887..f39d106740 100644
--- a/include/nuttx/compiler.h
+++ b/include/nuttx/compiler.h
@@ -53,11 +53,18 @@
  * excluded from the link.
  */
 
-# define CONFIG_HAVE_WEAKFUNCTIONS 1
-# define weak_alias(name, aliasname) \
-  extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
-# define weak_function __attribute__ ((weak))
-# define weak_const_function __attribute__ ((weak, __const__))
+# ifndef __CYGWIN__
+#  define CONFIG_HAVE_WEAKFUNCTIONS 1
+#  define weak_alias(name, aliasname) \
+   extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
+#  define weak_function __attribute__ ((weak))
+#  define weak_const_function __attribute__ ((weak, __const__))
+# else
+#  undef  CONFIG_HAVE_WEAKFUNCTIONS
+#  define weak_alias(name, aliasname)
+#  define weak_function
+#  define weak_const_function
+#endif
 
 /* The noreturn attribute informs GCC that the function will
  * not return.
diff --git a/net/send.c b/net/send.c
index 57e19ade77..dc5dbc75b7 100644
--- a/net/send.c
+++ b/net/send.c
@@ -165,12 +165,14 @@ static void send_interrupt(struct uip_driver_s *dev, void *private)
     {
       /* Stop further callbacks */
 
-      uip_udp_conn->private = NULL;
-      uip_udp_conn->event   = NULL;
+      conn               = (struct uip_conn *)pstate->snd_sock->s_conn;
+      conn->data_private = NULL;
+      conn->data_event   = NULL;
 
       /* Report not connected */
 
       pstate->snd_sent = -ENOTCONN;
+
       /* Wake up the waiting thread */
 
       sem_post(&pstate->snd_sem);
diff --git a/net/socket.c b/net/socket.c
index b35c8e8662..5efc86df9b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -88,9 +88,7 @@
 
 int socket(int domain, int type, int protocol)
 {
-#ifdef CONFIG_NET_UDP
   FAR struct socket *psock;
-#endif
   int sockfd;
   int err;
 
diff --git a/net/uip/uip.c b/net/uip/uip.c
index 677cf64db6..49536fa413 100644
--- a/net/uip/uip.c
+++ b/net/uip/uip.c
@@ -372,7 +372,9 @@ void uip_init(void)
 
   /* Initialize the UDP connection structures */
 
+#ifdef CONFIG_NET_UDP
   uip_udpinit();
+#endif
 
   /* IPv4 initialization. */
 }
@@ -561,6 +563,7 @@ static void uip_add_rcv_nxt(uint16 n)
   uip_conn->rcv_nxt[3] = uip_acc32[3];
 }
 
+#ifdef CONFIG_NET_UDP
 static void uip_udp_callback(struct uip_driver_s *dev)
 {
   /* Some sanity checking */
@@ -572,6 +575,7 @@ static void uip_udp_callback(struct uip_driver_s *dev)
       uip_udp_conn->event(dev, uip_udp_conn->private);
     }
 }
+#endif
 
 static void uip_tcp_callback(struct uip_driver_s *dev)
 {