diff --git a/arch/sim/Kconfig b/arch/sim/Kconfig
index b0395968d7..7384d3d723 100644
--- a/arch/sim/Kconfig
+++ b/arch/sim/Kconfig
@@ -100,6 +100,39 @@ config SIM_WALLTIME
 		correct for the system timer tick rate.  With this definition in the configuration,
 		sleep() behavior is more or less normal.
 
+if HOST_LINUX
+choice
+	prompt "Simulation Network Type"
+	default SIM_NET_HOST_ROUTE
+
+config SIM_NET_HOST_ROUTE
+	bool "Use local host route"
+	---help---
+		Add a host route for the simulation that points to the created tap device.  The
+		simulation will not be able to access the public network unless iptables is
+		configured to masquerade for it.  See configs/sim/NETWORK-LINUX.txt for more 
+		information.
+
+config SIM_NET_BRIDGE
+	bool "Attach to Linux bridge"
+	 ---help---
+		Add the created tap device to the specified bridge.  You will need to manually
+		configure the bridge IP address (if any) and routes that point to the bridge.
+		See configs/sim/NETWORK-LINUX.txt for more information.
+
+endchoice
+endif
+
+if SIM_NET_BRIDGE
+config SIM_NET_BRIDGE_DEVICE
+	string "Bridge device to attach"
+	default "nuttx0"
+	---help---
+		The name of the bridge device (as passed to "brctl create") to which the simulation's
+		TAP interface should be added.
+
+endif
+
 config SIM_LCDDRIVER
 	bool "Build a simulated LCD driver"
 	default y
diff --git a/arch/sim/src/Makefile b/arch/sim/src/Makefile
index 1e3f52744a..72401d6c77 100644
--- a/arch/sim/src/Makefile
+++ b/arch/sim/src/Makefile
@@ -120,6 +120,13 @@ ifeq ($(CONFIG_NET_ETHERNET),y)
   HOSTCFLAGS += -DNETDEV_BUFSIZE=$(CONFIG_NET_ETH_MTU)
 ifneq ($(HOSTOS),Cygwin)
   HOSTSRCS += up_tapdev.c up_netdev.c
+ifeq ($(CONFIG_SIM_NET_BRIDGE),y)
+  HOSTCFLAGS += -DCONFIG_SIM_NET_BRIDGE
+  HOSTCFLAGS += -DCONFIG_SIM_NET_BRIDGE_DEVICE=\"$(CONFIG_SIM_NET_BRIDGE_DEVICE)\"
+endif
+ifeq ($(CONFIG_SIM_NET_HOST_ROUTE),y)
+  HOSTCFLAGS += -DCONFIG_SIM_NET_HOST_ROUTE
+endif
 else
   HOSTSRCS += up_wpcap.c up_netdev.c
   DRVLIB = /lib/w32api/libws2_32.a /lib/w32api/libiphlpapi.a
diff --git a/arch/sim/src/up_internal.h b/arch/sim/src/up_internal.h
index e1e69dc25b..ddae194a6a 100644
--- a/arch/sim/src/up_internal.h
+++ b/arch/sim/src/up_internal.h
@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/sim/src/up_internal.h
  *
- *   Copyright (C) 2007, 2009, 2011-2012, 2014 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011-2012, 2014, 2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -46,6 +46,7 @@
 #ifndef __ASSEMBLY__
 #  include <sys/types.h>
 #  include <stdbool.h>
+#  include <netinet/in.h>
 
 #  include <nuttx/irq.h>
 #  include <arch/irq.h>
@@ -308,10 +309,14 @@ int sim_ajoy_initialize(void);
 void tapdev_init(void);
 unsigned int tapdev_read(unsigned char *buf, unsigned int buflen);
 void tapdev_send(unsigned char *buf, unsigned int buflen);
+void tapdev_ifup(in_addr_t ifaddr);
+void tapdev_ifdown(void);
 
-#define netdev_init()           tapdev_init()
-#define netdev_read(buf,buflen) tapdev_read(buf,buflen)
-#define netdev_send(buf,buflen) tapdev_send(buf,buflen)
+#  define netdev_init()           tapdev_init()
+#  define netdev_read(buf,buflen) tapdev_read(buf,buflen)
+#  define netdev_send(buf,buflen) tapdev_send(buf,buflen)
+#  define netdev_ifup(ifaddr)     tapdev_ifup(ifaddr)
+#  define netdev_ifdown()         tapdev_ifdown()
 #endif
 
 /* up_wpcap.c *************************************************************/
@@ -321,9 +326,11 @@ void wpcap_init(void);
 unsigned int wpcap_read(unsigned char *buf, unsigned int buflen);
 void wpcap_send(unsigned char *buf, unsigned int buflen);
 
-#define netdev_init()           wpcap_init()
-#define netdev_read(buf,buflen) wpcap_read(buf,buflen)
-#define netdev_send(buf,buflen) wpcap_send(buf,buflen)
+#  define netdev_init()           wpcap_init()
+#  define netdev_read(buf,buflen) wpcap_read(buf,buflen)
+#  define netdev_send(buf,buflen) wpcap_send(buf,buflen)
+#  define netdev_ifup(ifaddr)     {}
+#  define netdev_ifdown()         {}
 #endif
 
 /* up_netdriver.c *********************************************************/
diff --git a/arch/sim/src/up_netdriver.c b/arch/sim/src/up_netdriver.c
index 346159157f..c785f49746 100644
--- a/arch/sim/src/up_netdriver.c
+++ b/arch/sim/src/up_netdriver.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/sim/src/up_netdriver.c
  *
- *   Copyright (C) 2007, 2009-2012, 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009-2012, 2015-2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Based on code from uIP which also has a BSD-like license:
@@ -186,21 +186,32 @@ void netdriver_loop(void)
        */
 
       eth = BUF;
-      if (g_sim_dev.d_len > ETH_HDRLEN &&
-          up_comparemac(eth->dest, &g_sim_dev.d_mac) == 0)
+      if (g_sim_dev.d_len > ETH_HDRLEN)
         {
+         int is_ours;
+
+         /* Figure out if this ethernet frame is addressed to us.  This affects
+           * what we're willing to receive.   Note that in promiscuous mode, the
+           * up_comparemac will always return 0.
+           */
+
+         is_ours = (up_comparemac(eth->dest, &g_sim_dev.d_mac) == 0);
+
 #ifdef CONFIG_NET_PKT
           /* When packet sockets are enabled, feed the frame into the packet
            * tap.
            */
 
-          pkt_input(&g_sim_dev);
+          if (is_ours)
+            {
+              pkt_input(&g_sim_dev);
+            }
 #endif
 
           /* We only accept IP packets of the configured type and ARP packets */
 
 #ifdef CONFIG_NET_IPv4
-          if (eth->type == HTONS(ETHTYPE_IP))
+          if (eth->type == HTONS(ETHTYPE_IP) && is_ours)
             {
               nllvdbg("IPv4 frame\n");
 
@@ -241,7 +252,7 @@ void netdriver_loop(void)
           else
 #endif
 #ifdef CONFIG_NET_IPv6
-          if (eth->type == HTONS(ETHTYPE_IP6))
+          if (eth->type == HTONS(ETHTYPE_IP6) && is_ours)
             {
               nllvdbg("Iv6 frame\n");
 
@@ -304,9 +315,22 @@ void netdriver_loop(void)
       timer_reset(&g_periodic_timer);
       devif_timer(&g_sim_dev, sim_txpoll);
     }
+
   sched_unlock();
 }
 
+int netdriver_ifup(struct net_driver_s *dev)
+{
+  netdev_ifup(dev->d_ipaddr);
+  return OK;
+}
+
+int netdriver_ifdown(struct net_driver_s *dev)
+{
+  netdev_ifdown();
+  return OK;
+}
+
 int netdriver_init(void)
 {
   /* Internal initalization */
@@ -314,6 +338,11 @@ int netdriver_init(void)
   timer_set(&g_periodic_timer, 500);
   netdev_init();
 
+  /* Set callbacks */
+
+  g_sim_dev.d_ifup   = netdriver_ifup;
+  g_sim_dev.d_ifdown = netdriver_ifdown;
+
   /* Register the device with the OS so that socket IOCTLs can be performed */
 
   (void)netdev_register(&g_sim_dev, NET_LL_ETHERNET);
diff --git a/arch/sim/src/up_tapdev.c b/arch/sim/src/up_tapdev.c
index 4fc1394e37..c3ed52e791 100644
--- a/arch/sim/src/up_tapdev.c
+++ b/arch/sim/src/up_tapdev.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/sim/src/up_tapdev.c
  *
- *   Copyright (C) 2007-2009, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011, 2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Based on code from uIP which also has a BSD-like license:
@@ -56,30 +56,25 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <string.h>
+#include <time.h>
 
-#include <linux/if.h>
+#ifdef CONFIG_SIM_NET_HOST_ROUTE
+#  include <net/route.h>
+#endif
+
+#include <net/if.h>
+#include <linux/sockios.h>
 #include <linux/if_tun.h>
 #include <linux/net.h>
+#include <netinet/in.h>
 
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define TAPDEV_DEBUG    1
+//#define TAPDEV_DEBUG  1
 
-#define DEVTAP          "/dev/net/tun"
-
-#ifndef CONFIG_EXAMPLES_WEBSERVER_DHCPC
-#  define TAP_IPADDR0   192
-#  define TAP_IPADDR1   168
-#  define TAP_IPADDR2   0
-#  define TAP_IPADDR3   128
-#else
-#  define TAP_IPADDR0   0
-#  define TAP_IPADDR1   0
-#  define TAP_IPADDR2   0
-#  define TAP_IPADDR3   0
-#endif
+#define DEVTAP        "/dev/net/tun"
 
 /* Syslog priority (must match definitions in nuttx/include/syslog.h) */
 
@@ -101,10 +96,6 @@ struct sel_arg_struct
   struct timeval *tvp;
 };
 
-/****************************************************************************
- * Private Function Prototypes
- ****************************************************************************/
-
 /****************************************************************************
  * NuttX Domain Public Function Prototypes
  ****************************************************************************/
@@ -117,9 +108,14 @@ int netdriver_setmacaddr(unsigned char *macaddr);
  ****************************************************************************/
 
 #ifdef TAPDEV_DEBUG
-static int gdrop = 0;
+static int  gdrop = 0;
+#endif
+static int  gtapdevfd;
+static char gdevname[IFNAMSIZ];
+
+#ifdef CONFIG_SIM_NET_HOST_ROUTE
+static struct rtentry ghostroute;
 #endif
-static int gtapdevfd;
 
 /****************************************************************************
  * Private Functions
@@ -145,32 +141,32 @@ static inline void dump_ethhdr(const char *msg, unsigned char *buf, int buflen)
 
 static int up_setmacaddr(void)
 {
-  int sockfd;
+  unsigned char mac[7];
   int ret = -1;
 
-  /* Get a socket (only so that we get access to the INET subsystem) */
+  /* Assign a random locally-created MAC address.
+   *
+   * This previously took the address from the TAP interface; that was
+   * incorrect, as that hardware address belongs to the host system.  Packets
+   * destined for the application aren't guaranteed to reach it if you do
+   * that, as the host may handle them at its discretion.
+   *
+   * With a unique MAC address, we get ALL the packets.
+   *
+   * TODO:  The generated MAC address should be checked to see if it
+   *        conflicts with something else on the network.
+   */
 
-  sockfd = socket(PF_INET, SOCK_DGRAM, 0);
-  if (sockfd >= 0)
-    {
-      struct ifreq req;
-      memset(&req, 0, sizeof(struct ifreq));
-
-      /* Put the driver name into the request */
-
-      strncpy(req.ifr_name, "tap0", IFNAMSIZ);
-
-      /* Perform the ioctl to get the MAC address */
-
-      ret = ioctl(sockfd, SIOCGIFHWADDR, (unsigned long)&req);
-      if (!ret)
-        {
-          /* Set the MAC address */
-
-          ret = netdriver_setmacaddr((unsigned char *)&req.ifr_hwaddr.sa_data);
-        }
-    }
+  srand(time(NULL));
+  mac[0] = 0x42;
+  mac[1] = rand() % 256;
+  mac[2] = rand() % 256;
+  mac[3] = rand() % 256;
+  mac[4] = rand() % 256;
+  mac[5] = rand() % 256;
+  mac[6] = 0;
 
+  ret = netdriver_setmacaddr(mac);
   return ret;
 }
 
@@ -181,9 +177,12 @@ static int up_setmacaddr(void)
 void tapdev_init(void)
 {
   struct ifreq ifr;
-  char buf[1024];
   int ret;
 
+#ifdef CONFIG_SIM_NET_BRIDGE
+  int sockfd;
+#endif
+
   /* Open the tap device */
 
   gtapdevfd = open(DEVTAP, O_RDWR, 0644);
@@ -204,11 +203,37 @@ void tapdev_init(void)
       return;
    }
 
-  /* Assign an IPv4 address to the tap device */
+  /* Save the tap device name */
 
-  snprintf(buf, sizeof(buf), "/sbin/ifconfig tap0 inet %d.%d.%d.%d\n",
-           TAP_IPADDR0, TAP_IPADDR1, TAP_IPADDR2, TAP_IPADDR3);
-  system(buf);
+  strncpy(gdevname, ifr.ifr_name, IFNAMSIZ);
+
+#ifdef CONFIG_SIM_NET_BRIDGE
+  /* Get a socket with which to manipulate the tap device; the remaining
+   * ioctl calls unfortunately won't work on the tap device fd.
+   */
+
+  sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+  if (sockfd < 0)
+    {
+      syslog(LOG_ERR, "TAPDEV: Can't open socket: %d\n", -sockfd);
+      return;
+    }
+
+  /* Assign the tap device to a bridge */
+
+  memset(&ifr, 0, sizeof(ifr));
+  strncpy(ifr.ifr_name, CONFIG_SIM_NET_BRIDGE_DEVICE, IFNAMSIZ);
+  ifr.ifr_ifindex = if_nametoindex(gdevname);
+
+  ret = ioctl(sockfd, SIOCBRADDIF, &ifr);
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "TAPDEV: ioctl failed (can't add interface %s to bridge %s): %d\n",
+             devname, CONFIG_SIM_NET_BRIDGE_DEVICE, -ret);
+    }
+
+  close(sockfd);
+#endif
 
   /* Set the MAC address */
 
@@ -273,9 +298,101 @@ void tapdev_send(unsigned char *buf, unsigned int buflen)
       syslog(LOG_ERR, "TAPDEV: write failed: %d", -ret);
       exit(1);
     }
+
   dump_ethhdr("write", buf, buflen);
 }
 
+void tapdev_ifup(in_addr_t ifaddr)
+{
+  struct ifreq ifr;
+  int          sockfd;
+  int          ret;
+
+#ifdef CONFIG_SIM_NET_HOST_ROUTE
+  struct sockaddr_in *addr;
+#endif
+
+  /* Get a socket with which to manipulate the tap device */
+
+  sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+  if (sockfd < 0)
+    {
+      syslog(LOG_ERR, "TAPDEV: Can't open socket: %d\n", -sockfd);
+      return;
+    }
+
+  /* Bring the TAP interface up */
+
+  strncpy(ifr.ifr_name, gdevname, IFNAMSIZ);
+
+  ret = ioctl(sockfd, SIOCGIFFLAGS, (unsigned long)&ifr);
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "TAPDEV: ioctl failed (can't get interface flags): %d\n", -ret);
+      close(sockfd);
+      return;
+    }
+
+  ifr.ifr_flags |= IFF_UP;
+  ret = ioctl(sockfd, SIOCSIFFLAGS, (unsigned long)&ifr);
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "TAPDEV: ioctl failed (can't set interface flags): %d\n", -ret);
+      close(sockfd);
+      return;
+    }
+
+#ifdef CONFIG_SIM_NET_HOST_ROUTE
+  /* Add host route */
+
+  memset(&ghostroute, 0, sizeof(ghostroute));
+
+  addr = (struct sockaddr_in *)&ghostroute.rt_dst;
+  addr->sin_family = AF_INET;
+  addr->sin_addr.s_addr = ifaddr;
+
+  ghostroute.rt_dev    = gdevname;
+  ghostroute.rt_flags  = RTF_UP | RTF_HOST;
+  ghostroute.rt_metric = 0;
+
+  ret = ioctl(sockfd, SIOCADDRT, (unsigned long)&ghostroute);
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "TAPDEV: ioctl failed (can't add host route): %d\n", -ret);
+      close(sockfd);
+      return;
+    }
+#endif
+
+  close(sockfd);
+}
+
+void tapdev_ifdown(void)
+{
+#ifdef CONFIG_SIM_NET_HOST_ROUTE
+  int sockfd;
+  int ret;
+
+  if (((struct sockaddr_in *)&ghostroute.rt_dst)->sin_addr.s_addr != 0)
+    {
+      /* Get a socket with which to manipulate the tap device */
+
+      sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+      if (sockfd < 0)
+        {
+          syslog(LOG_ERR, "TAPDEV: Can't open socket: %d\n", -sockfd);
+          return;
+        }
+
+      ret = ioctl(sockfd, SIOCDELRT, (unsigned long)&ghostroute);
+      if (ret < 0)
+        {
+          syslog(LOG_ERR, "TAPDEV: ioctl failed (can't delete host route): %d\n", -ret);
+        }
+
+      close(sockfd);
+    }
+#endif
+}
+
 #endif /* !__CYGWIN__ */
-
-
diff --git a/configs/sim/nettest/defconfig b/configs/sim/nettest/defconfig
index 80ce9f678f..acfdb50999 100644
--- a/configs/sim/nettest/defconfig
+++ b/configs/sim/nettest/defconfig
@@ -37,6 +37,7 @@ CONFIG_BUILD_FLAT=y
 # CONFIG_ARCH_MATH_H is not set
 # CONFIG_ARCH_FLOAT_H is not set
 # CONFIG_ARCH_STDARG_H is not set
+# CONFIG_ARCH_DEBUG_H is not set
 
 #
 # Debug Options
@@ -73,6 +74,8 @@ CONFIG_HOST_X86_64=y
 CONFIG_SIM_X8664_SYSTEMV=y
 # CONFIG_SIM_X8664_MICROSOFT is not set
 # CONFIG_SIM_WALLTIME is not set
+CONFIG_SIM_NET_HOST_ROUTE=y
+# CONFIG_SIM_NET_BRIDGE is not set
 # CONFIG_SIM_FRAMEBUFFER is not set
 # CONFIG_SIM_SPIFLASH is not set
 
@@ -87,6 +90,7 @@ CONFIG_SIM_X8664_SYSTEMV=y
 # CONFIG_ARCH_HAVE_COHERENT_DCACHE is not set
 # CONFIG_ARCH_HAVE_ADDRENV is not set
 # CONFIG_ARCH_NEED_ADDRENV_MAPPING is not set
+CONFIG_ARCH_HAVE_MULTICPU=y
 # CONFIG_ARCH_HAVE_VFORK is not set
 # CONFIG_ARCH_HAVE_MMU is not set
 # CONFIG_ARCH_HAVE_MPU is not set
@@ -230,9 +234,10 @@ CONFIG_SIG_SIGCONDTIMEDOUT=16
 #
 CONFIG_PREALLOC_MQ_MSGS=32
 CONFIG_MQ_MAXMSGSIZE=32
+# CONFIG_MODULE is not set
 
 #
-# Work Queue Support
+# Work queue support
 #
 # CONFIG_SCHED_WORKQUEUE is not set
 # CONFIG_SCHED_HPWORK is not set
@@ -281,8 +286,16 @@ CONFIG_DEV_NULL=y
 # CONFIG_VIDEO_DEVICES is not set
 # CONFIG_BCH is not set
 # CONFIG_INPUT is not set
+# CONFIG_IOEXPANDER is not set
 # CONFIG_LCD is not set
+
+#
+# LED Support
+#
+# CONFIG_RGBLED is not set
+# CONFIG_PCA9635PW is not set
 # CONFIG_MMCSD is not set
+# CONFIG_MODEM is not set
 # CONFIG_MTD is not set
 # CONFIG_EEPROM is not set
 # CONFIG_NETDEVICES is not set
@@ -475,7 +488,9 @@ CONFIG_FS_FAT=y
 # CONFIG_FAT_LCNAMES is not set
 # CONFIG_FAT_LFN is not set
 # CONFIG_FS_FATTIME is not set
+# CONFIG_FAT_FORCE_INDIRECT is not set
 # CONFIG_FAT_DMAMEMORY is not set
+# CONFIG_FAT_DIRECT_RETRY is not set
 # CONFIG_FS_NXFFS is not set
 # CONFIG_FS_ROMFS is not set
 # CONFIG_FS_TMPFS is not set
@@ -508,6 +523,10 @@ CONFIG_MM_REGIONS=1
 #
 # CONFIG_AUDIO is not set
 
+#
+# Wireless Support
+#
+
 #
 # Binary Loader
 #
@@ -553,6 +572,8 @@ CONFIG_ARCH_LOWPUTC=y
 CONFIG_LIB_SENDFILE_BUFSIZE=512
 # CONFIG_ARCH_ROMGETC is not set
 # CONFIG_ARCH_OPTIMIZED_FUNCTIONS is not set
+CONFIG_ARCH_HAVE_TLS=y
+# CONFIG_TLS is not set
 # CONFIG_LIBC_NETDB is not set
 # CONFIG_NETDB_HOSTFILE is not set
 
@@ -579,6 +600,7 @@ CONFIG_LIB_SENDFILE_BUFSIZE=512
 #
 # Examples
 #
+# CONFIG_EXAMPLES_CHAT is not set
 # CONFIG_EXAMPLES_CONFIGDATA is not set
 # CONFIG_EXAMPLES_CPUHOG is not set
 # CONFIG_EXAMPLES_DHCPD is not set
@@ -620,11 +642,12 @@ CONFIG_EXAMPLES_NETTEST_CLIENTIP=0xc0a8006a
 # CONFIG_EXAMPLES_NXLINES is not set
 # CONFIG_EXAMPLES_NXTEXT is not set
 # CONFIG_EXAMPLES_OSTEST is not set
+# CONFIG_EXAMPLES_PCA9635 is not set
 # CONFIG_EXAMPLES_PIPE is not set
 # CONFIG_EXAMPLES_POLL is not set
 # CONFIG_EXAMPLES_PPPD is not set
 # CONFIG_EXAMPLES_POSIXSPAWN is not set
-# CONFIG_EXAMPLES_QENCODER is not set
+# CONFIG_EXAMPLES_RGBLED is not set
 # CONFIG_EXAMPLES_RGMP is not set
 # CONFIG_EXAMPLES_SENDMAIL is not set
 # CONFIG_EXAMPLES_SERIALBLASTER is not set
@@ -632,12 +655,12 @@ CONFIG_EXAMPLES_NETTEST_CLIENTIP=0xc0a8006a
 # CONFIG_EXAMPLES_SERLOOP is not set
 # CONFIG_EXAMPLES_SLCD is not set
 # CONFIG_EXAMPLES_SMART is not set
+# CONFIG_EXAMPLES_SMP is not set
 # CONFIG_EXAMPLES_TCPECHO is not set
 # CONFIG_EXAMPLES_TELNETD is not set
 # CONFIG_EXAMPLES_TIFF is not set
 # CONFIG_EXAMPLES_TOUCHSCREEN is not set
 # CONFIG_EXAMPLES_WEBSERVER is not set
-# CONFIG_EXAMPLES_USBSERIAL is not set
 # CONFIG_EXAMPLES_USBTERM is not set
 # CONFIG_EXAMPLES_WATCHDOG is not set
 # CONFIG_EXAMPLES_WGET is not set
@@ -645,6 +668,13 @@ CONFIG_EXAMPLES_NETTEST_CLIENTIP=0xc0a8006a
 #
 # File System Utilities
 #
+# CONFIG_FSUTILS_INIFILE is not set
+# CONFIG_FSUTILS_PASSWD is not set
+
+#
+# GPS Utilities
+#
+# CONFIG_GPSUTILS_MINMEA_LIB is not set
 
 #
 # Graphics Support
@@ -700,11 +730,11 @@ CONFIG_NETUTILS_NETLIB=y
 # CONFIG_SYSTEM_CUTERM is not set
 # CONFIG_SYSTEM_INSTALL is not set
 # CONFIG_SYSTEM_HEX2BIN is not set
-# CONFIG_FSUTILS_INIFILE is not set
 # CONFIG_SYSTEM_HEXED is not set
 # CONFIG_SYSTEM_RAMTEST is not set
 # CONFIG_READLINE_HAVE_EXTMATCH is not set
 # CONFIG_SYSTEM_READLINE is not set
 # CONFIG_SYSTEM_SUDOKU is not set
 # CONFIG_SYSTEM_VI is not set
+# CONFIG_SYSTEM_UBLOXMODEM is not set
 # CONFIG_SYSTEM_ZMODEM is not set
diff --git a/configs/sim/udgram/defconfig b/configs/sim/udgram/defconfig
index bf678170a0..c46a0d0bdd 100644
--- a/configs/sim/udgram/defconfig
+++ b/configs/sim/udgram/defconfig
@@ -37,6 +37,7 @@ CONFIG_BUILD_FLAT=y
 # CONFIG_ARCH_MATH_H is not set
 # CONFIG_ARCH_FLOAT_H is not set
 # CONFIG_ARCH_STDARG_H is not set
+# CONFIG_ARCH_DEBUG_H is not set
 
 #
 # Debug Options
@@ -73,6 +74,8 @@ CONFIG_HOST_X86_64=y
 CONFIG_SIM_X8664_SYSTEMV=y
 # CONFIG_SIM_X8664_MICROSOFT is not set
 CONFIG_SIM_WALLTIME=y
+CONFIG_SIM_NET_HOST_ROUTE=y
+# CONFIG_SIM_NET_BRIDGE is not set
 # CONFIG_SIM_FRAMEBUFFER is not set
 # CONFIG_SIM_SPIFLASH is not set
 
@@ -87,6 +90,7 @@ CONFIG_SIM_WALLTIME=y
 # CONFIG_ARCH_HAVE_COHERENT_DCACHE is not set
 # CONFIG_ARCH_HAVE_ADDRENV is not set
 # CONFIG_ARCH_NEED_ADDRENV_MAPPING is not set
+CONFIG_ARCH_HAVE_MULTICPU=y
 # CONFIG_ARCH_HAVE_VFORK is not set
 # CONFIG_ARCH_HAVE_MMU is not set
 # CONFIG_ARCH_HAVE_MPU is not set
@@ -242,9 +246,10 @@ CONFIG_SIG_SIGCONDTIMEDOUT=16
 #
 CONFIG_PREALLOC_MQ_MSGS=32
 CONFIG_MQ_MAXMSGSIZE=32
+# CONFIG_MODULE is not set
 
 #
-# Work Queue Support
+# Work queue support
 #
 # CONFIG_SCHED_WORKQUEUE is not set
 # CONFIG_SCHED_HPWORK is not set
@@ -293,8 +298,16 @@ CONFIG_DEV_NULL=y
 # CONFIG_VIDEO_DEVICES is not set
 # CONFIG_BCH is not set
 # CONFIG_INPUT is not set
+# CONFIG_IOEXPANDER is not set
 # CONFIG_LCD is not set
+
+#
+# LED Support
+#
+# CONFIG_RGBLED is not set
+# CONFIG_PCA9635PW is not set
 # CONFIG_MMCSD is not set
+# CONFIG_MODEM is not set
 # CONFIG_MTD is not set
 # CONFIG_EEPROM is not set
 # CONFIG_NETDEVICES is not set
@@ -464,13 +477,16 @@ CONFIG_FAT_LCNAMES=y
 CONFIG_FAT_LFN=y
 CONFIG_FAT_MAXFNAME=32
 # CONFIG_FS_FATTIME is not set
+# CONFIG_FAT_FORCE_INDIRECT is not set
 # CONFIG_FAT_DMAMEMORY is not set
+# CONFIG_FAT_DIRECT_RETRY is not set
 # CONFIG_FS_NXFFS is not set
 CONFIG_FS_ROMFS=y
 # CONFIG_FS_TMPFS is not set
 # CONFIG_FS_SMARTFS is not set
 CONFIG_FS_BINFS=y
 CONFIG_FS_PROCFS=y
+# CONFIG_FS_PROCFS_REGISTER is not set
 
 #
 # Exclude individual procfs entries
@@ -506,6 +522,10 @@ CONFIG_MM_REGIONS=1
 #
 # CONFIG_AUDIO is not set
 
+#
+# Wireless Support
+#
+
 #
 # Binary Loader
 #
@@ -555,6 +575,8 @@ CONFIG_ARCH_LOWPUTC=y
 CONFIG_LIB_SENDFILE_BUFSIZE=512
 # CONFIG_ARCH_ROMGETC is not set
 # CONFIG_ARCH_OPTIMIZED_FUNCTIONS is not set
+CONFIG_ARCH_HAVE_TLS=y
+# CONFIG_TLS is not set
 CONFIG_LIBC_NETDB=y
 # CONFIG_NETDB_HOSTFILE is not set
 
@@ -586,6 +608,7 @@ CONFIG_BUILTIN_PROXY_STACKSIZE=1024
 #
 # Examples
 #
+# CONFIG_EXAMPLES_CHAT is not set
 # CONFIG_EXAMPLES_CONFIGDATA is not set
 # CONFIG_EXAMPLES_CPUHOG is not set
 # CONFIG_EXAMPLES_DHCPD is not set
@@ -594,6 +617,8 @@ CONFIG_BUILTIN_PROXY_STACKSIZE=1024
 # CONFIG_EXAMPLES_FTPC is not set
 # CONFIG_EXAMPLES_FTPD is not set
 CONFIG_EXAMPLES_HELLO=y
+CONFIG_EXAMPLES_HELLO_PRIORITY=100
+CONFIG_EXAMPLES_HELLO_STACKSIZE=2048
 # CONFIG_EXAMPLES_JSON is not set
 # CONFIG_EXAMPLES_HIDKBD is not set
 # CONFIG_EXAMPLES_KEYPADTEST is not set
@@ -613,10 +638,11 @@ CONFIG_EXAMPLES_NSH=y
 # CONFIG_EXAMPLES_NXLINES is not set
 # CONFIG_EXAMPLES_NXTEXT is not set
 # CONFIG_EXAMPLES_OSTEST is not set
+# CONFIG_EXAMPLES_PCA9635 is not set
 # CONFIG_EXAMPLES_PIPE is not set
 # CONFIG_EXAMPLES_PPPD is not set
 # CONFIG_EXAMPLES_POSIXSPAWN is not set
-# CONFIG_EXAMPLES_QENCODER is not set
+# CONFIG_EXAMPLES_RGBLED is not set
 # CONFIG_EXAMPLES_RGMP is not set
 # CONFIG_EXAMPLES_ROMFS is not set
 # CONFIG_EXAMPLES_SENDMAIL is not set
@@ -626,6 +652,7 @@ CONFIG_EXAMPLES_NSH=y
 # CONFIG_EXAMPLES_SLCD is not set
 # CONFIG_EXAMPLES_SMART_TEST is not set
 # CONFIG_EXAMPLES_SMART is not set
+# CONFIG_EXAMPLES_SMP is not set
 # CONFIG_EXAMPLES_TCPECHO is not set
 # CONFIG_EXAMPLES_TELNETD is not set
 # CONFIG_EXAMPLES_THTTPD is not set
@@ -649,6 +676,13 @@ CONFIG_EXAMPLES_UDGRAM_CLIENT_PRIORITY=100
 #
 # File System Utilities
 #
+# CONFIG_FSUTILS_INIFILE is not set
+# CONFIG_FSUTILS_PASSWD is not set
+
+#
+# GPS Utilities
+#
+# CONFIG_GPSUTILS_MINMEA_LIB is not set
 
 #
 # Graphics Support
@@ -682,6 +716,7 @@ CONFIG_NETUTILS_NETLIB=y
 # NSH Library
 #
 CONFIG_NSH_LIBRARY=y
+# CONFIG_NSH_MOTD is not set
 
 #
 # Command Line Configuration
@@ -742,6 +777,7 @@ CONFIG_NSH_DISABLE_LOSMART=y
 # CONFIG_NSH_DISABLE_SET is not set
 # CONFIG_NSH_DISABLE_SH is not set
 # CONFIG_NSH_DISABLE_SLEEP is not set
+# CONFIG_NSH_DISABLE_TIME is not set
 # CONFIG_NSH_DISABLE_TEST is not set
 # CONFIG_NSH_DISABLE_UMOUNT is not set
 # CONFIG_NSH_DISABLE_UNAME is not set
@@ -796,6 +832,8 @@ CONFIG_NSH_ARCHINIT=y
 #
 # CONFIG_NSH_NOMAC is not set
 CONFIG_NSH_MAX_ROUNDTRIP=20
+# CONFIG_NSH_LOGIN is not set
+# CONFIG_NSH_CONSOLE_LOGIN is not set
 
 #
 # NxWidgets/NxWM
@@ -814,7 +852,6 @@ CONFIG_NSH_MAX_ROUNDTRIP=20
 # CONFIG_SYSTEM_CUTERM is not set
 # CONFIG_SYSTEM_INSTALL is not set
 # CONFIG_SYSTEM_HEX2BIN is not set
-# CONFIG_FSUTILS_INIFILE is not set
 # CONFIG_SYSTEM_HEXED is not set
 # CONFIG_SYSTEM_NETDB is not set
 # CONFIG_SYSTEM_RAMTEST is not set
@@ -826,4 +863,5 @@ CONFIG_READLINE_ECHO=y
 # CONFIG_SYSTEM_SUDOKU is not set
 # CONFIG_SYSTEM_VI is not set
 # CONFIG_SYSTEM_SYMTAB is not set
+# CONFIG_SYSTEM_UBLOXMODEM is not set
 # CONFIG_SYSTEM_ZMODEM is not set
diff --git a/configs/sim/ustream/defconfig b/configs/sim/ustream/defconfig
index 31a861a5ac..10b60384dc 100644
--- a/configs/sim/ustream/defconfig
+++ b/configs/sim/ustream/defconfig
@@ -37,6 +37,7 @@ CONFIG_BUILD_FLAT=y
 # CONFIG_ARCH_MATH_H is not set
 # CONFIG_ARCH_FLOAT_H is not set
 # CONFIG_ARCH_STDARG_H is not set
+# CONFIG_ARCH_DEBUG_H is not set
 
 #
 # Debug Options
@@ -73,6 +74,8 @@ CONFIG_HOST_X86_64=y
 CONFIG_SIM_X8664_SYSTEMV=y
 # CONFIG_SIM_X8664_MICROSOFT is not set
 CONFIG_SIM_WALLTIME=y
+CONFIG_SIM_NET_HOST_ROUTE=y
+# CONFIG_SIM_NET_BRIDGE is not set
 # CONFIG_SIM_FRAMEBUFFER is not set
 # CONFIG_SIM_SPIFLASH is not set
 
@@ -87,6 +90,7 @@ CONFIG_SIM_WALLTIME=y
 # CONFIG_ARCH_HAVE_COHERENT_DCACHE is not set
 # CONFIG_ARCH_HAVE_ADDRENV is not set
 # CONFIG_ARCH_NEED_ADDRENV_MAPPING is not set
+CONFIG_ARCH_HAVE_MULTICPU=y
 # CONFIG_ARCH_HAVE_VFORK is not set
 # CONFIG_ARCH_HAVE_MMU is not set
 # CONFIG_ARCH_HAVE_MPU is not set
@@ -242,9 +246,10 @@ CONFIG_SIG_SIGCONDTIMEDOUT=16
 #
 CONFIG_PREALLOC_MQ_MSGS=32
 CONFIG_MQ_MAXMSGSIZE=32
+# CONFIG_MODULE is not set
 
 #
-# Work Queue Support
+# Work queue support
 #
 # CONFIG_SCHED_WORKQUEUE is not set
 # CONFIG_SCHED_HPWORK is not set
@@ -293,8 +298,16 @@ CONFIG_DEV_NULL=y
 # CONFIG_VIDEO_DEVICES is not set
 # CONFIG_BCH is not set
 # CONFIG_INPUT is not set
+# CONFIG_IOEXPANDER is not set
 # CONFIG_LCD is not set
+
+#
+# LED Support
+#
+# CONFIG_RGBLED is not set
+# CONFIG_PCA9635PW is not set
 # CONFIG_MMCSD is not set
+# CONFIG_MODEM is not set
 # CONFIG_MTD is not set
 # CONFIG_EEPROM is not set
 # CONFIG_NETDEVICES is not set
@@ -464,13 +477,16 @@ CONFIG_FAT_LCNAMES=y
 CONFIG_FAT_LFN=y
 CONFIG_FAT_MAXFNAME=32
 # CONFIG_FS_FATTIME is not set
+# CONFIG_FAT_FORCE_INDIRECT is not set
 # CONFIG_FAT_DMAMEMORY is not set
+# CONFIG_FAT_DIRECT_RETRY is not set
 # CONFIG_FS_NXFFS is not set
 CONFIG_FS_ROMFS=y
 # CONFIG_FS_TMPFS is not set
 # CONFIG_FS_SMARTFS is not set
 CONFIG_FS_BINFS=y
 CONFIG_FS_PROCFS=y
+# CONFIG_FS_PROCFS_REGISTER is not set
 
 #
 # Exclude individual procfs entries
@@ -506,6 +522,10 @@ CONFIG_MM_REGIONS=1
 #
 # CONFIG_AUDIO is not set
 
+#
+# Wireless Support
+#
+
 #
 # Binary Loader
 #
@@ -555,6 +575,8 @@ CONFIG_ARCH_LOWPUTC=y
 CONFIG_LIB_SENDFILE_BUFSIZE=512
 # CONFIG_ARCH_ROMGETC is not set
 # CONFIG_ARCH_OPTIMIZED_FUNCTIONS is not set
+CONFIG_ARCH_HAVE_TLS=y
+# CONFIG_TLS is not set
 CONFIG_LIBC_NETDB=y
 # CONFIG_NETDB_HOSTFILE is not set
 
@@ -586,6 +608,7 @@ CONFIG_BUILTIN_PROXY_STACKSIZE=1024
 #
 # Examples
 #
+# CONFIG_EXAMPLES_CHAT is not set
 # CONFIG_EXAMPLES_CONFIGDATA is not set
 # CONFIG_EXAMPLES_CPUHOG is not set
 # CONFIG_EXAMPLES_DHCPD is not set
@@ -594,6 +617,8 @@ CONFIG_BUILTIN_PROXY_STACKSIZE=1024
 # CONFIG_EXAMPLES_FTPC is not set
 # CONFIG_EXAMPLES_FTPD is not set
 CONFIG_EXAMPLES_HELLO=y
+CONFIG_EXAMPLES_HELLO_PRIORITY=100
+CONFIG_EXAMPLES_HELLO_STACKSIZE=2048
 # CONFIG_EXAMPLES_JSON is not set
 # CONFIG_EXAMPLES_HIDKBD is not set
 # CONFIG_EXAMPLES_KEYPADTEST is not set
@@ -613,10 +638,11 @@ CONFIG_EXAMPLES_NSH=y
 # CONFIG_EXAMPLES_NXLINES is not set
 # CONFIG_EXAMPLES_NXTEXT is not set
 # CONFIG_EXAMPLES_OSTEST is not set
+# CONFIG_EXAMPLES_PCA9635 is not set
 # CONFIG_EXAMPLES_PIPE is not set
 # CONFIG_EXAMPLES_PPPD is not set
 # CONFIG_EXAMPLES_POSIXSPAWN is not set
-# CONFIG_EXAMPLES_QENCODER is not set
+# CONFIG_EXAMPLES_RGBLED is not set
 # CONFIG_EXAMPLES_RGMP is not set
 # CONFIG_EXAMPLES_ROMFS is not set
 # CONFIG_EXAMPLES_SENDMAIL is not set
@@ -626,6 +652,7 @@ CONFIG_EXAMPLES_NSH=y
 # CONFIG_EXAMPLES_SLCD is not set
 # CONFIG_EXAMPLES_SMART_TEST is not set
 # CONFIG_EXAMPLES_SMART is not set
+# CONFIG_EXAMPLES_SMP is not set
 # CONFIG_EXAMPLES_TCPECHO is not set
 # CONFIG_EXAMPLES_TELNETD is not set
 # CONFIG_EXAMPLES_THTTPD is not set
@@ -644,6 +671,13 @@ CONFIG_EXAMPLES_USTREAM_ADDR="/dev/fifo"
 #
 # File System Utilities
 #
+# CONFIG_FSUTILS_INIFILE is not set
+# CONFIG_FSUTILS_PASSWD is not set
+
+#
+# GPS Utilities
+#
+# CONFIG_GPSUTILS_MINMEA_LIB is not set
 
 #
 # Graphics Support
@@ -677,6 +711,7 @@ CONFIG_NETUTILS_NETLIB=y
 # NSH Library
 #
 CONFIG_NSH_LIBRARY=y
+# CONFIG_NSH_MOTD is not set
 
 #
 # Command Line Configuration
@@ -737,6 +772,7 @@ CONFIG_NSH_DISABLE_LOSMART=y
 # CONFIG_NSH_DISABLE_SET is not set
 # CONFIG_NSH_DISABLE_SH is not set
 # CONFIG_NSH_DISABLE_SLEEP is not set
+# CONFIG_NSH_DISABLE_TIME is not set
 # CONFIG_NSH_DISABLE_TEST is not set
 # CONFIG_NSH_DISABLE_UMOUNT is not set
 # CONFIG_NSH_DISABLE_UNAME is not set
@@ -791,6 +827,8 @@ CONFIG_NSH_ARCHINIT=y
 #
 # CONFIG_NSH_NOMAC is not set
 CONFIG_NSH_MAX_ROUNDTRIP=20
+# CONFIG_NSH_LOGIN is not set
+# CONFIG_NSH_CONSOLE_LOGIN is not set
 
 #
 # NxWidgets/NxWM
@@ -809,7 +847,6 @@ CONFIG_NSH_MAX_ROUNDTRIP=20
 # CONFIG_SYSTEM_CUTERM is not set
 # CONFIG_SYSTEM_INSTALL is not set
 # CONFIG_SYSTEM_HEX2BIN is not set
-# CONFIG_FSUTILS_INIFILE is not set
 # CONFIG_SYSTEM_HEXED is not set
 # CONFIG_SYSTEM_NETDB is not set
 # CONFIG_SYSTEM_RAMTEST is not set
@@ -821,4 +858,5 @@ CONFIG_READLINE_ECHO=y
 # CONFIG_SYSTEM_SUDOKU is not set
 # CONFIG_SYSTEM_VI is not set
 # CONFIG_SYSTEM_SYMTAB is not set
+# CONFIG_SYSTEM_UBLOXMODEM is not set
 # CONFIG_SYSTEM_ZMODEM is not set
diff --git a/net/arp/arp_send.c b/net/arp/arp_send.c
index b6431582b1..0fff9041c3 100644
--- a/net/arp/arp_send.c
+++ b/net/arp/arp_send.c
@@ -344,7 +344,10 @@ int arp_send(in_addr_t ipaddr)
        * its single argument to lookup the network interface.
        */
 
-      dev->d_txavail(dev);
+      if (dev->d_txavail)
+        {
+          dev->d_txavail(dev);
+        }
 
       /* Wait for the send to complete or an error to occur: NOTES: (1)
        * net_lockedwait will also terminate if a signal is received, (2)