More QEMU logic

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3337 42af7a65-404d-4744-a932-0658087f49c3

19 files changed, 1477 insertions, 36 deletions

diff --git a/nuttx/arch/x86/include/i486/arch.h b/nuttx/arch/x86/include/i486/arch.h
index 89901cb0a..fcce94fa4 100755
--- a/nuttx/arch/x86/include/i486/arch.h
+++ b/nuttx/arch/x86/include/i486/arch.h
@@ -44,6 +44,11 @@
  * Included Files
  ****************************************************************************/
 
+#include <nuttx/config.h>
+#ifndef __ASSEMBLY__
+#  include <stdint.h>
+#endif
+
 /****************************************************************************
  * Definitions
  ****************************************************************************/
@@ -80,6 +85,22 @@
  * Inline functions
  ****************************************************************************/
 
+#ifndef __ASSEMBLY__
+
+/* Return stack pointer */
+
+static inline uint32_t up_getsp()
+{
+  uint32_t regval;
+
+  asm volatile(
+    "\tmovl %%esp, %0\n"
+    : "=rm" (regval)
+    :
+    : "memory");
+  return regval;
+}
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -104,5 +125,6 @@ extern "C" {
 }
 #endif
 
+#endif /* __ASSEMBLY__ */
 #endif /* __ARCH_X86_INCLUDE_I486_ARCH_H */
 
diff --git a/nuttx/arch/x86/include/i486/io.h b/nuttx/arch/x86/include/i486/io.h
index 7a56ef626..b5a4e0ec1 100644
--- a/nuttx/arch/x86/include/i486/io.h
+++ b/nuttx/arch/x86/include/i486/io.h
@@ -113,7 +113,7 @@ static inline void outl(uint32_t regval, uint16_t port)
     );
 }
 
-static inline uint32_t inl(uint32_t port)
+static inline uint32_t inl(uint16_t port)
 {
   uint32_t regval;
   asm volatile(
diff --git a/nuttx/arch/x86/include/i486/irq.h b/nuttx/arch/x86/include/i486/irq.h
index d24e335f1..7f6d849ba 100755
--- a/nuttx/arch/x86/include/i486/irq.h
+++ b/nuttx/arch/x86/include/i486/irq.h
@@ -44,7 +44,7 @@
  * Included Files
  ****************************************************************************/
 
-#ifdef __ASSEMBLY__
+#ifndef __ASSEMBLY__
 #  include <stdint.h>
 #  include <stdbool.h>
 #  include <arch/arch.h>
diff --git a/nuttx/arch/x86/src/Makefile b/nuttx/arch/x86/src/Makefile
index 9281828bb..e34e85338 100644
--- a/nuttx/arch/x86/src/Makefile
+++ b/nuttx/arch/x86/src/Makefile
@@ -42,13 +42,13 @@ ARCH_SUBDIR	= i486
 endif
 
 ifeq ($(WINTOOL),y)
-  NUTTX		= "${shell cygpath -w $(TOPDIR)/nuttx}"
+  NUTTX		= "${shell cygpath -w $(TOPDIR)/nuttx$(EXEEXT)}"
   CFLAGS	+= -I "${shell cygpath -w $(ARCH_SRCDIR)/chip}" \
   		   -I "${shell cygpath -w $(ARCH_SRCDIR)/common}" \
 		   -I "${shell cygpath -w $(ARCH_SRCDIR)/$(ARCH_SUBDIR)}" \
 		   -I "${shell cygpath -w $(TOPDIR)/sched}"
 else
-  NUTTX		= $(TOPDIR)/nuttx
+  NUTTX		= $(TOPDIR)/nuttx$(EXEEXT)
   CFLAGS	+= -I$(ARCH_SRCDIR)/chip -I$(ARCH_SRCDIR)/common \
 		   -I$(ARCH_SRCDIR)/$(ARCH_SUBDIR) -I$(TOPDIR)/sched
 endif
@@ -99,8 +99,8 @@ libarch$(LIBEXT): $(OBJS)
 board/libboard$(LIBEXT):
 	@$(MAKE) -C board TOPDIR="$(TOPDIR)" libboard$(LIBEXT)
 
-nuttx: $(HEAD_AOBJ) board/libboard$(LIBEXT)
-	@echo "LD: nuttx"
+nuttx$(EXEEXT): $(HEAD_AOBJ) board/libboard$(LIBEXT)
+	@echo "LD: nuttx$(EXEEXT)"
 	@$(LD) --entry=__start $(LDFLAGS) $(LIBPATHS) -o $(NUTTX)$(EXEEXT) $(HEAD_AOBJ) $(EXTRA_OBJS) \
 		--start-group $(LDLIBS) -lboard --end-group $(EXTRA_LIBS) $(LIBGCC)
 ifeq ($(CONFIG_BOOT_RUNFROMFLASH),y)
diff --git a/nuttx/arch/x86/src/common/up_blocktask.c b/nuttx/arch/x86/src/common/up_blocktask.c
new file mode 100755
index 000000000..60606b75e
--- /dev/null
+++ b/nuttx/arch/x86/src/common/up_blocktask.c
@@ -0,0 +1,166 @@
+/****************************************************************************
+ * arch/x86/src/common/up_blocktask.c
+ *
+ *   Copyright (C) 2010 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_block_task
+ *
+ * Description:
+ *   The currently executing task at the head of the ready to run list must
+ *   be stopped.  Save its context and move it to the inactive list specified
+ *   by task_state.
+ *
+ * Inputs:
+ *   tcb: Refers to a task in the ready-to-run list (normally the task at the
+ *     head of the list).  It most be stopped, its context saved and moved
+ *     into one of the waiting task lists.  It it was the task at the head
+ *     of the ready-to-run list, then a context to the new ready to run task
+ *     must be performed.
+ *   task_state: Specifies which waiting task list should be
+ *     hold the blocked task TCB.
+ *
+ ****************************************************************************/
+
+void up_block_task(_TCB *tcb, tstate_t task_state)
+{
+  /* Verify that the context switch can be performed */
+
+  if ((tcb->task_state < FIRST_READY_TO_RUN_STATE) ||
+      (tcb->task_state > LAST_READY_TO_RUN_STATE))
+    {
+      PANIC(OSERR_BADBLOCKSTATE);
+    }
+  else
+    {
+      _TCB *rtcb = (_TCB*)g_readytorun.head;
+      bool switch_needed;
+
+      /* Remove the tcb task from the ready-to-run list.  If we
+       * are blocking the task at the head of the task list (the
+       * most likely case), then a context switch to the next
+       * ready-to-run task is needed. In this case, it should
+       * also be true that rtcb == tcb.
+       */
+
+      switch_needed = sched_removereadytorun(tcb);
+
+      /* Add the task to the specified blocked task list */
+
+      sched_addblocked(tcb, (tstate_t)task_state);
+
+      /* If there are any pending tasks, then add them to the g_readytorun
+       * task list now
+       */
+
+      if (g_pendingtasks.head)
+        {
+          switch_needed |= sched_mergepending();
+        }
+
+      /* Now, perform the context switch if one is needed */
+
+      if (switch_needed)
+        {
+          /* Are we in an interrupt handler? */
+
+          if (current_regs)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current_regs into the OLD rtcb.
+               */
+
+               up_savestate(rtcb->xcp.regs);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+
+              /* Then switch contexts */
+
+              up_restorestate(rtcb->xcp.regs);
+            }
+
+          /* Copy the user C context into the TCB at the (old) head of the
+           * g_readytorun Task list. if up_saveusercontext returns a non-zero
+           * value, then this is really the previously running task restarting!
+           */
+
+          else if (!up_saveusercontext(rtcb->xcp.regs))
+            {
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+
+              /* Then switch contexts */
+
+              up_fullcontextrestore(rtcb->xcp.regs);
+            }
+        }
+    }
+}
diff --git a/nuttx/arch/x86/src/common/up_copystate.c b/nuttx/arch/x86/src/common/up_copystate.c
new file mode 100644
index 000000000..983cd52fa
--- /dev/null
+++ b/nuttx/arch/x86/src/common/up_copystate.c
@@ -0,0 +1,82 @@
+/****************************************************************************
+ * arch/x86/src/common/up_copystate.c
+ *
+ *   Copyright (C) 2010 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_undefinedinsn
+ ****************************************************************************/
+
+/* A little faster than most memcpy's */
+
+void up_copystate(uint32_t *dest, uint32_t *src)
+{
+  int i;
+
+  /* In the current ARM model, the state is always copied to and from the
+   * stack and TCB.
+   */
+
+  for (i = 0; i < XCPTCONTEXT_REGS; i++)
+    {
+      *dest++ = *src++;
+    }
+}
+
diff --git a/nuttx/arch/x86/src/common/up_releasepending.c b/nuttx/arch/x86/src/common/up_releasepending.c
new file mode 100755
index 000000000..dcad40159
--- /dev/null
+++ b/nuttx/arch/x86/src/common/up_releasepending.c
@@ -0,0 +1,132 @@
+/****************************************************************************
+ *  arch/arm/src/arm/up_releasepending.c
+ *
+ *   Copyright (C) 2007-2009 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_release_pending
+ *
+ * Description:
+ *   Release and ready-to-run tasks that have
+ *   collected in the pending task list.  This can call a
+ *   context switch if a new task is placed at the head of
+ *   the ready to run list.
+ *
+ ****************************************************************************/
+
+void up_release_pending(void)
+{
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+
+  slldbg("From TCB=%p\n", rtcb);
+
+  /* Merge the g_pendingtasks list into the g_readytorun task list */
+
+  /* sched_lock(); */
+  if (sched_mergepending())
+    {
+      /* The currently active task has changed!  We will need to
+       * switch contexts.  First check if we are operating in
+       * interrupt context:
+       */
+
+      if (current_regs)
+        {
+          /* Yes, then we have to do things differently.
+           * Just copy the current_regs into the OLD rtcb.
+           */
+
+           up_savestate(rtcb->xcp.regs);
+
+          /* Restore the exception context of the rtcb at the (new) head 
+           * of the g_readytorun task list.
+           */
+
+          rtcb = (_TCB*)g_readytorun.head;
+          slldbg("New Active Task TCB=%p\n", rtcb);
+
+          /* Then switch contexts */
+
+          up_restorestate(rtcb->xcp.regs);
+        }
+
+      /* Copy the exception context into the TCB of the task that
+       * was currently active. if up_saveusercontext returns a non-zero
+       * value, then this is really the previously running task 
+       * restarting!
+       */
+
+      else if (!up_saveusercontext(rtcb->xcp.regs))
+        {
+          /* Restore the exception context of the rtcb at the (new) head 
+           * of the g_readytorun task list.
+           */
+
+          rtcb = (_TCB*)g_readytorun.head;
+          slldbg("New Active Task TCB=%p\n", rtcb);
+
+           /* Then switch contexts */
+
+          up_fullcontextrestore(rtcb->xcp.regs);
+        }
+    }
+}
diff --git a/nuttx/arch/x86/src/common/up_reprioritizertr.c b/nuttx/arch/x86/src/common/up_reprioritizertr.c
new file mode 100755
index 000000000..38bce2a72
--- /dev/null
+++ b/nuttx/arch/x86/src/common/up_reprioritizertr.c
@@ -0,0 +1,187 @@
+/****************************************************************************
+ *  arch/arm/src/arm/up_reprioritizertr.c
+ *
+ *   Copyright (C) 2007-2009 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_reprioritize_rtr
+ *
+ * Description:
+ *   Called when the priority of a running or
+ *   ready-to-run task changes and the reprioritization will 
+ *   cause a context switch.  Two cases:
+ *
+ *   1) The priority of the currently running task drops and the next
+ *      task in the ready to run list has priority.
+ *   2) An idle, ready to run task's priority has been raised above the
+ *      the priority of the current, running task and it now has the
+ *      priority.
+ *
+ * Inputs:
+ *   tcb: The TCB of the task that has been reprioritized
+ *   priority: The new task priority
+ *
+ ****************************************************************************/
+
+void up_reprioritize_rtr(_TCB *tcb, uint8_t priority)
+{
+  /* Verify that the caller is sane */
+
+  if (tcb->task_state < FIRST_READY_TO_RUN_STATE ||
+      tcb->task_state > LAST_READY_TO_RUN_STATE
+#if SCHED_PRIORITY_MIN > 0
+      || priority < SCHED_PRIORITY_MIN
+#endif
+#if SCHED_PRIORITY_MAX < UINT8_MAX
+      || priority > SCHED_PRIORITY_MAX
+#endif
+    )
+    {
+       PANIC(OSERR_BADREPRIORITIZESTATE);
+    }
+  else
+    {
+      _TCB *rtcb = (_TCB*)g_readytorun.head;
+      bool switch_needed;
+
+      slldbg("TCB=%p PRI=%d\n", tcb, priority);
+
+      /* Remove the tcb task from the ready-to-run list.
+       * sched_removereadytorun will return true if we just
+       * remove the head of the ready to run list.
+       */
+
+      switch_needed = sched_removereadytorun(tcb);
+
+      /* Setup up the new task priority */
+
+      tcb->sched_priority = (uint8_t)priority;
+
+      /* Return the task to the specified blocked task list.
+       * sched_addreadytorun will return true if the task was
+       * added to the new list.  We will need to perform a context
+       * switch only if the EXCLUSIVE or of the two calls is non-zero
+       * (i.e., one and only one the calls changes the head of the
+       * ready-to-run list).
+       */
+
+      switch_needed ^= sched_addreadytorun(tcb);
+
+      /* Now, perform the context switch if one is needed */
+
+      if (switch_needed)
+        {
+          /* If we are going to do a context switch, then now is the right
+           * time to add any pending tasks back into the ready-to-run list.
+           * task list now
+           */
+
+          if (g_pendingtasks.head)
+            {
+              sched_mergepending();
+            }
+
+         /* Are we in an interrupt handler? */
+
+          if (current_regs)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current_regs into the OLD rtcb.
+               */
+
+               up_savestate(rtcb->xcp.regs);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+              slldbg("New Active Task TCB=%p\n", rtcb);
+
+              /* Then switch contexts */
+
+              up_restorestate(rtcb->xcp.regs);
+            }
+
+          /* Copy the exception context into the TCB at the (old) head of the
+           * g_readytorun Task list. if up_saveusercontext returns a non-zero
+           * value, then this is really the previously running task restarting!
+           */
+
+          else if (!up_saveusercontext(rtcb->xcp.regs))
+            {
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+              slldbg("New Active Task TCB=%p\n", rtcb);
+
+              /* Then switch contexts */
+
+              up_fullcontextrestore(rtcb->xcp.regs);
+            }
+        }
+    }
+}
diff --git a/nuttx/arch/x86/src/common/up_unblocktask.c b/nuttx/arch/x86/src/common/up_unblocktask.c
new file mode 100755
index 000000000..31304e4ad
--- /dev/null
+++ b/nuttx/arch/x86/src/common/up_unblocktask.c
@@ -0,0 +1,158 @@
+/****************************************************************************
+ *  arch/x86/src/common/up_unblocktask.c
+ *
+ *   Copyright (C) 2010 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "clock_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_unblock_task
+ *
+ * Description:
+ *   A task is currently in an inactive task list but has been prepped to
+ *   execute.  Move the TCB to the ready-to-run list, restore its context,
+ *   and start execution.
+ *
+ * Inputs:
+ *   tcb: Refers to the tcb to be unblocked.  This tcb is in one of the
+ *     waiting tasks lists.  It must be moved to the ready-to-run list and,
+ *     if it is the highest priority ready to run taks, executed.
+ *
+ ****************************************************************************/
+
+void up_unblock_task(_TCB *tcb)
+{
+  /* Verify that the context switch can be performed */
+
+  if ((tcb->task_state < FIRST_BLOCKED_STATE) ||
+      (tcb->task_state > LAST_BLOCKED_STATE))
+    {
+      PANIC(OSERR_BADUNBLOCKSTATE);
+    }
+  else
+    {
+      _TCB *rtcb = (_TCB*)g_readytorun.head;
+
+      /* Remove the task from the blocked task list */
+
+      sched_removeblocked(tcb);
+
+      /* Reset its timeslice.  This is only meaningful for round
+       * robin tasks but it doesn't here to do it for everything
+       */
+
+#if CONFIG_RR_INTERVAL > 0
+      tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+#endif
+
+      /* Add the task in the correct location in the prioritized
+       * g_readytorun task list
+       */
+
+      if (sched_addreadytorun(tcb))
+        {
+          /* The currently active task has changed! We need to do
+           * a context switch to the new task.
+           *
+           * Are we in an interrupt handler? 
+           */
+
+          if (current_regs)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current_regs into the OLD rtcb.
+               */
+
+               up_savestate(rtcb->xcp.regs);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+
+              /* Then switch contexts */
+
+              up_restorestate(rtcb->xcp.regs);
+            }
+
+          /* We are not in an interrupt handler.  Copy the user C context
+           * into the TCB of the task that was previously active.  if 
+           * up_saveusercontext returns a non-zero value, then this is really the
+           * previously running task restarting!
+           */
+
+          else if (!up_saveusercontext(rtcb->xcp.regs))
+            {
+              /* Restore the exception context of the new task that is ready to
+               * run (probably tcb).  This is the new rtcb at the head of the
+               * g_readytorun task list.
+               */
+
+              rtcb = (_TCB*)g_readytorun.head;
+
+              /* Then switch contexts */
+
+              up_fullcontextrestore(rtcb->xcp.regs);
+            }
+        }
+    }
+}
diff --git a/nuttx/arch/x86/src/i486/up_assert.c b/nuttx/arch/x86/src/i486/up_assert.c
new file mode 100644
index 000000000..77d6ca3ba
--- /dev/null
+++ b/nuttx/arch/x86/src/i486/up_assert.c
@@ -0,0 +1,300 @@
+/****************************************************************************
+ * arch/x86/src/i486/up_assert.c
+ *
+ *   Copyright (C) 2010 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/arch.h>
+#include <arch/board/board.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Output debug info if stack dump is selected -- even if 
+ * debug is not selected.
+ */
+
+#ifdef CONFIG_ARCH_STACKDUMP
+# undef  lldbg
+# define lldbg lib_lowprintf
+#endif
+
+/* The following is just intended to keep some ugliness out of the mainline
+ * code.  We are going to print the task name if:
+ *
+ *  CONFIG_TASK_NAME_SIZE > 0 &&    <-- The task has a name
+ *  (defined(CONFIG_DEBUG)    ||    <-- And the debug is enabled (lldbg used)
+ *   defined(CONFIG_ARCH_STACKDUMP) <-- Or lib_lowprintf() is used
+ */
+
+#undef CONFIG_PRINT_TASKNAME
+#if CONFIG_TASK_NAME_SIZE > 0 && (defined(CONFIG_DEBUG) || defined(CONFIG_ARCH_STACKDUMP))
+#  define CONFIG_PRINT_TASKNAME 1
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_stackdump
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static void up_stackdump(uint32_t sp, uint32_t stack_base)
+{
+  uint32_t stack ;
+
+  for (stack = sp & ~0x1f; stack < stack_base; stack += 32)
+    {
+      uint32_t *ptr = (uint32_t*)stack;
+      lldbg("%08x: %08x %08x %08x %08x %08x %08x %08x %08x\n",
+             stack, ptr[0], ptr[1], ptr[2], ptr[3],
+             ptr[4], ptr[5], ptr[6], ptr[7]);
+    }
+}
+#else
+# define up_stackdump()
+#endif
+
+/****************************************************************************
+ * Name: up_registerdump
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static inline void up_registerdump(void)
+{
+  /* Are user registers available from interrupt processing? */
+
+  if (current_regs)
+    {
+      lldbg("ebx:%08x esi:%08x edi:%08x ebp:%08x\n",
+            current_regs[REG_EBX], current_regs[REG_ESI], current_regs[REG_EDI], current_regs[REG_EBP]);
+      lldbg(" sp:%08x  pc:%08x\n",
+            current_regs[REG_SP], current_regs[REG_PC]);
+    }
+}
+#else
+# define up_registerdump()
+#endif
+
+/****************************************************************************
+ * Name: up_dumpstate
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static void up_dumpstate(void)
+{
+  _TCB    *rtcb = (_TCB*)g_readytorun.head;
+  uint32_t sp   = up_getsp();
+  uint32_t ustackbase;
+  uint32_t ustacksize;
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  uint32_t istackbase;
+  uint32_t istacksize;
+#endif
+
+  /* Get the limits on the user stack memory */
+
+  if (rtcb->pid == 0)
+    {
+      ustackbase = g_heapbase - 4;
+      ustacksize = CONFIG_IDLETHREAD_STACKSIZE;
+    }
+  else
+    {
+      ustackbase = (uint32_t)rtcb->adj_stack_ptr;
+      ustacksize = (uint32_t)rtcb->adj_stack_size;
+    }
+
+  /* Get the limits on the interrupt stack memory */
+
+#if CONFIG_ARCH_INTERRUPTSTACK > 3
+  istackbase = (uint32_t)&g_userstack;
+  istacksize = (CONFIG_ARCH_INTERRUPTSTACK & ~3) - 4;
+
+  /* Show interrupt stack info */
+
+  lldbg("sp:     %08x\n", sp);
+  lldbg("IRQ stack:\n");
+  lldbg("  base: %08x\n", istackbase);
+  lldbg("  size: %08x\n", istacksize);
+
+  /* Does the current stack pointer lie within the interrupt
+   * stack?
+   */
+
+  if (sp <= istackbase && sp > istackbase - istacksize)
+    {
+      /* Yes.. dump the interrupt stack */
+
+      up_stackdump(sp, istackbase);
+
+      /* Extract the user stack pointer which should lie
+       * at the base of the interrupt stack.
+       */
+
+      sp = g_userstack;
+      lldbg("sp:     %08x\n", sp);
+    }
+
+  /* Show user stack info */
+
+  lldbg("User stack:\n");
+  lldbg("  base: %08x\n", ustackbase);
+  lldbg("  size: %08x\n", ustacksize);
+#else
+  lldbg("sp:         %08x\n", sp);
+  lldbg("stack base: %08x\n", ustackbase);
+  lldbg("stack size: %08x\n", ustacksize);
+#endif
+
+  /* Dump the user stack if the stack pointer lies within the allocated user
+   * stack memory.
+   */
+
+  if (sp > ustackbase || sp <= ustackbase - ustacksize)
+    {
+#if !defined(CONFIG_ARCH_INTERRUPTSTACK) || CONFIG_ARCH_INTERRUPTSTACK < 4
+      lldbg("ERROR: Stack pointer is not within allocated stack\n");
+#endif
+    }
+  else
+    {
+      up_stackdump(sp, ustackbase);
+    }
+
+  /* Then dump the registers (if available) */
+
+  up_registerdump();
+}
+#else
+# define up_dumpstate()
+#endif
+
+/****************************************************************************
+ * Name: _up_assert
+ ****************************************************************************/
+
+static void _up_assert(int errorcode) /* __attribute__ ((noreturn)) */
+{
+  /* Are we in an interrupt handler or the idle task? */
+
+  if (current_regs || ((_TCB*)g_readytorun.head)->pid == 0)
+    {
+       (void)irqsave();
+        for(;;)
+          {
+#ifdef CONFIG_ARCH_LEDS
+            up_ledon(LED_PANIC);
+            up_mdelay(250);
+            up_ledoff(LED_PANIC);
+            up_mdelay(250);
+#endif
+          }
+    }
+  else
+    {
+      exit(errorcode);
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_assert
+ ****************************************************************************/
+
+void up_assert(const uint8_t *filename, int lineno)
+{
+#ifdef CONFIG_PRINT_TASKNAME
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+#endif
+
+  up_ledon(LED_ASSERTION);
+#ifdef CONFIG_PRINT_TASKNAME
+  lldbg("Assertion failed at file:%s line: %d task: %s\n",
+        filename, lineno, rtcb->name);
+#else
+  lldbg("Assertion failed at file:%s line: %d\n",
+        filename, lineno);
+#endif
+  up_dumpstate();
+  _up_assert(EXIT_FAILURE);
+}
+
+/****************************************************************************
+ * Name: up_assert_code
+ ****************************************************************************/
+
+void up_assert_code(const uint8_t *filename, int lineno, int errorcode)
+{
+#ifdef CONFIG_PRINT_TASKNAME
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+#endif
+
+  up_ledon(LED_ASSERTION);
+
+#ifdef CONFIG_PRINT_TASKNAME
+  lldbg("Assertion failed at file:%s line: %d task: %s error code: %d\n",
+        filename, lineno, rtcb->name, errorcode);
+#else
+  lldbg("Assertion failed at file:%s line: %d error code: %d\n",
+        filename, lineno, errorcode);
+#endif
+  up_dumpstate();
+  _up_assert(errorcode);
+}
diff --git a/nuttx/arch/x86/src/qemu/Make.defs b/nuttx/arch/x86/src/qemu/Make.defs
index 5e88c117e..c7a65ea10 100755
--- a/nuttx/arch/x86/src/qemu/Make.defs
+++ b/nuttx/arch/x86/src/qemu/Make.defs
@@ -40,13 +40,17 @@ HEAD_ASRC	= qemu_head.S
 # Common x86 and i486 files
 
 CMN_ASRCS	= 
-CMN_CSRCS	= up_createstack.c up_mdelay.c up_udelay.c up_exit.c up_initialize.c \
-		  up_interruptcontext.c up_modifyreg8.c up_modifyreg16.c \
-		  up_modifyreg32.c up_releasestack.c up_usestack.c
+CMN_CSRCS	= up_allocateheap.c up_assert.c up_blocktask.c up_copystate.c \
+			  up_createstack.c up_mdelay.c up_udelay.c up_exit.c \
+			  up_initialize.c up_interruptcontext.c up_modifyreg8.c \
+			  up_modifyreg16.c up_modifyreg32.c up_releasepending.c \
+			  up_releasestack.c up_reprioritizertr.c up_unblocktask.c \
+			  up_usestack.c
 
 # Required QEMU files
 
 CHIP_ASRCS	= qemu_saveusercontext.S qemu_fullcontextrestore.S
-CHIP_CSRCS	= qemu_idle.c
+CHIP_CSRCS	= qemu_idle.c qemu_irq.c qemu_lowputc.c qemu_lowsetup.c \
+			  qemu_timerisr.c
 
 # Configuration-dependent QEMU files
diff --git a/nuttx/arch/x86/src/qemu/qemu_fullcontextrestore.S b/nuttx/arch/x86/src/qemu/qemu_fullcontextrestore.S
index b70ab0984..49f1e5ee6 100644
--- a/nuttx/arch/x86/src/qemu/qemu_fullcontextrestore.S
+++ b/nuttx/arch/x86/src/qemu/qemu_fullcontextrestore.S
@@ -101,15 +101,15 @@ SYMBOL(up_fullcontextrestore):
 
 	/* Save the return address now.  */
 
-	movl (JB_PC)(%ecx), %edx
+	movl (REG_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
+	movl (REG_EBX)(%ecx), %ebx
+	movl (REG_ESI)(%ecx), %esi
+	movl (REG_EDI)(%ecx), %edi
+	movl (REG_EBP)(%ecx), %ebp
+	movl (REG_SP)(%ecx), %esp
 
 	/* Jump to saved PC.  */
 
diff --git a/nuttx/arch/x86/src/qemu/qemu_head.S b/nuttx/arch/x86/src/qemu/qemu_head.S
index a1c816827..9d436b4fd 100755
--- a/nuttx/arch/x86/src/qemu/qemu_head.S
+++ b/nuttx/arch/x86/src/qemu/qemu_head.S
@@ -44,7 +44,7 @@
  ****************************************************************************/

 

 #ifdef CONFIG_X86_NASM

-global		loader						/* Making entry point visible to linker */

+global		__start						/* Making entry point visible to linker */

 extern		os_start					/* os_start is defined elsewhere */

 extern		up_lowsetup					/* up_lowsetup is defined elsewhere */

  

@@ -67,7 +67,7 @@ MultiBootHeader:
 

 STACKSIZE	equ	0x4000					/* That's 16k */

  

-loader:

+__start:

 	mov		esp, stack+STACKSIZE		/* Set up the stack */

 	push	eax							/* Pass Multiboot magic number */

 	push	ebx							/* Pass Multiboot info structure */

@@ -85,11 +85,11 @@ align 4
 stack:

 	resb STACKSIZE						/* Reserve 16k stack on a doubleword boundary */

 

-#else /* GAS */

+#else /* !CONFIG_X86_NASM (GAS) */

 

-	.global	loader						/* Making entry point visible to linker */

-	.global	os_start					/* os_start is defined elsewhere */

-	.global	up_lowsetup					/* up_lowsetup is defined elsewhere */

+	.global	__start						/* Making entry point visible to linker */

+	.global	_os_start					/* os_start is defined elsewhere */

+	.global	_up_lowsetup				/* up_lowsetup is defined elsewhere */

 

 /* Setting up the Multiboot header - see GRUB docs for details */

 

@@ -109,18 +109,17 @@ stack:
 	.set	STACKSIZE, 0x4000			/* That is, 16k */

 	.comm	stack, STACKSIZE, 32		/* Reserve 16k stack on a quadword boundary */

 

-loader:

+__start:

 	mov		$(stack + STACKSIZE), %esp	/* Set up the stack */

 	push	%eax						/* Multiboot magic number */

 	push	%ebx						/* Multiboot data structure */

 

-	call	up_lowsetup					/* Low-level, pre-OS initialization */

-	call	os_start					/* Start NuttX */

+	call	_up_lowsetup				/* Low-level, pre-OS initialization */

+	call	_os_start					/* Start NuttX */

 

 	cli

 hang:

 	hlt									/* Halt machine should NuttX return */

 	jmp	hang

-#endif

 	.end

-#endif
\ No newline at end of file
+#endif /* CONFIG_X86_NASM */
\ No newline at end of file
diff --git a/nuttx/arch/x86/src/qemu/qemu_irq.c b/nuttx/arch/x86/src/qemu/qemu_irq.c
new file mode 100755
index 000000000..6d16cfc92
--- /dev/null
+++ b/nuttx/arch/x86/src/qemu/qemu_irq.c
@@ -0,0 +1,160 @@
+/****************************************************************************
+ * arch/x86/src/qemu/qemu_irq.c
+ * arch/x86/src/chip/qemu_irq.c
+ *
+ *   Copyright (C) 2011 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <arch/irq.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+#include "qemu_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+uint32_t *current_regs;
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_irqinitialize
+ ****************************************************************************/
+
+void up_irqinitialize(void)
+{
+  /* Disable all interrupts */
+
+  /* currents_regs is non-NULL only while processing an interrupt */
+
+  current_regs = NULL;
+
+  /* Initialize logic to support a second level of interrupt decoding for
+   * GPIO pins.
+   */
+ 
+#ifdef CONFIG_GPIO_IRQ
+  lpc17_gpioirqinitialize();
+#endif
+
+  /* And finally, enable interrupts */
+
+#ifndef CONFIG_SUPPRESS_INTERRUPTS
+  irqrestore(0);
+#endif
+}
+
+/****************************************************************************
+ * Name: up_disable_irq
+ *
+ * Description:
+ *   Disable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_disable_irq(int irq)
+{
+#warning "Missing Logic"
+}
+
+/****************************************************************************
+ * Name: up_enable_irq
+ *
+ * Description:
+ *   Enable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_enable_irq(int irq)
+{
+#warning "Missing Logic"
+}
+
+/****************************************************************************
+ * Name: up_maskack_irq
+ *
+ * Description:
+ *   Mask the IRQ and acknowledge it
+ *
+ ****************************************************************************/
+
+void up_maskack_irq(int irq)
+{
+#warning "Missing Logic"
+}
+
+/****************************************************************************
+ * Name: up_prioritize_irq
+ *
+ * Description:
+ *   Set the priority of an IRQ.
+ *
+ *   Since this API is not supported on all architectures, it should be
+ *   avoided in common implementations where possible.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_IRQPRIO
+int up_prioritize_irq(int irq, int priority)
+{
+#warning "Missing Logic"
+  return OK;
+}
+#endif
diff --git a/nuttx/arch/x86/src/qemu/qemu_lowputc.c b/nuttx/arch/x86/src/qemu/qemu_lowputc.c
new file mode 100644
index 000000000..16d4425cc
--- /dev/null
+++ b/nuttx/arch/x86/src/qemu/qemu_lowputc.c
@@ -0,0 +1,72 @@
+/****************************************************************************
+ *  arch/x86/src/qemu/qemu_lowputc.c
+ *
+ *   Copyright (C) 2011 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <arch/io.h>
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/**************************************************************************
+ * Name: up_lowputc
+ *
+ * Description:
+ *   Output one byte on the serial console
+ *
+ **************************************************************************/
+
+void up_lowputc(char ch)
+{
+  outb(ch, 0x3f8);
+}
+
diff --git a/nuttx/arch/x86/src/qemu/qemu_lowsetup.c b/nuttx/arch/x86/src/qemu/qemu_lowsetup.c
new file mode 100644
index 000000000..ef48f0e7b
--- /dev/null
+++ b/nuttx/arch/x86/src/qemu/qemu_lowsetup.c
@@ -0,0 +1,80 @@
+/****************************************************************************
+ *  arch/x86/src/qemu/qemu_lowsetup.c
+ *
+ *   Copyright (C) 2011 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_lowsetup
+ *
+ * Description:
+ *   Called from qemu_head BEFORE starting the operating system in order
+ *   perform any necessary, early initialization.
+ *
+ ****************************************************************************/
+
+void up_lowsetup(void)
+{
+  /* Perform chip-specific initializations */
+
+  /* Now perform board-specific initializations */
+
+  up_boardinitialize();
+}
+
diff --git a/nuttx/arch/x86/src/qemu/qemu_timerisr.c b/nuttx/arch/x86/src/qemu/qemu_timerisr.c
new file mode 100755
index 000000000..072a54aa9
--- /dev/null
+++ b/nuttx/arch/x86/src/qemu/qemu_timerisr.c
@@ -0,0 +1,84 @@
+/****************************************************************************
+ * arch/x86/src/qemu/qemu_timerisr.c
+ *
+ *   Copyright (C) 2011 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <time.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "clock_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+#include "chip.h"
+#include "qemu_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function:  up_timerinit
+ *
+ * Description:
+ *   This function is called during start-up to initialize
+ *   the timer interrupt.
+ *
+ ****************************************************************************/
+
+void up_timerinit(void)
+{
+#warning "Not implemented"
+}
diff --git a/nuttx/configs/qemu-i486/ostest/Make.defs b/nuttx/configs/qemu-i486/ostest/Make.defs
index e92dc4c5f..c27cac0ef 100644
--- a/nuttx/configs/qemu-i486/ostest/Make.defs
+++ b/nuttx/configs/qemu-i486/ostest/Make.defs
@@ -80,12 +80,7 @@ AFLAGS = $(CFLAGS) -D__ASSEMBLY__
 
 OBJEXT = .o
 LIBEXT = .a
-
-ifeq ($(HOSTOS),Cygwin)
-  EXEEXT = .exe
-else
-  EXEEXT =
-endif
+EXEEXT = .elf
 
 ifeq ("${CONFIG_DEBUG_SYMBOLS}","y")
   LDFLAGS += -g
diff --git a/nuttx/configs/qemu-i486/ostest/ld.script b/nuttx/configs/qemu-i486/ostest/ld.script
index 3f2ff760a..0996f5310 100755
--- a/nuttx/configs/qemu-i486/ostest/ld.script
+++ b/nuttx/configs/qemu-i486/ostest/ld.script
@@ -33,7 +33,7 @@
  *
  ****************************************************************************/
 
-ENTRY(.loader)
+ENTRY(__start)
 SECTIONS
 {
 	. = 0x00100000;
@@ -64,7 +64,7 @@ SECTIONS
 		*(.gnu.linkonce.d.*)
 		CONSTRUCTORS
 		_edata = ABSOLUTE(.);
-	} > sram AT > flash
+	}
 
 	.bss : {
 		_sbss = ABSOLUTE(.);
@@ -72,7 +72,7 @@ SECTIONS
 		*(.gnu.linkonce.b.*)
 		*(COMMON)
 		_ebss = ABSOLUTE(.);
-	} > sram
+	}
 
 	/* Stabs debugging sections.	*/
 	.stab 0 : { *(.stab) }