Add QEMU interrupt handling (incomplete)

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3339 42af7a65-404d-4744-a932-0658087f49c3

9 files changed, 649 insertions, 26 deletions

diff --git a/nuttx/arch/x86/include/i486/arch.h b/nuttx/arch/x86/include/i486/arch.h
index fcce94fa4..f2c270067 100755
--- a/nuttx/arch/x86/include/i486/arch.h
+++ b/nuttx/arch/x86/include/i486/arch.h
@@ -82,6 +82,42 @@
 #define X86_EFLAGS_ID        (1 << 21) /* Bit 21: CPUID detection flag (Pentium+) */
 
 /****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/* GDT data structures
+ *
+ * The Global Descriptor Table or GDT is a data structure used by Intel x86-
+ * family processors starting with the 80286 in order to define the
+ * characteristics of the various memory areas used during program execution, 
+ * for example the base address, the size and access privileges like
+ * executability and writability. These memory areas are called segments in
+ * Intel terminology.
+ */
+
+/* This structure defines one segment */
+
+struct gdt_entry_s
+{
+  uint16_t lowlimit;           /* The lower 16 bits of the limit */
+  uint16_t lowbase;            /* The lower 16 bits of the base */
+  uint8_t  midbase;            /* The next 8 bits of the base */
+  uint8_t  access;             /* Access flags, determine ring segment can be used in */
+  uint8_t  granularity;
+  uint8_t  hibase;             /* The last 8 bits of the base */
+} __attribute__((packed));
+
+/* This structure refers to the array of GDT entries, and is in the format
+ * required by the lgdt instruction.
+ */
+
+struct gdt_ptr_s
+{
+  uint16_t limit;               /* The upper 16 bits of all selector limits */
+  uint32_t base;                /* The address of the first gdt_entry_t struct */
+} __attribute__((packed));
+
+/****************************************************************************
  * Inline functions
  ****************************************************************************/
 
diff --git a/nuttx/arch/x86/include/qemu/irq.h b/nuttx/arch/x86/include/qemu/irq.h
index a39876bc6..ef834b271 100755
--- a/nuttx/arch/x86/include/qemu/irq.h
+++ b/nuttx/arch/x86/include/qemu/irq.h
@@ -48,7 +48,57 @@
  * Definitions
  ****************************************************************************/
 
-#define NR_IRQS 0
+#define ISR0     0
+#define ISR1     1
+#define ISR2     2
+#define ISR3     3
+#define ISR4     4
+#define ISR5     5
+#define ISR6     6
+#define ISR7     7
+#define ISR8     8
+#define ISR9     9
+#define ISR10   10
+#define ISR11   11
+#define ISR12   12
+#define ISR13   13
+#define ISR14   14
+#define ISR15   15
+#define ISR16   16
+#define ISR17   17
+#define ISR18   18
+#define ISR19   19
+#define ISR20   20
+#define ISR21   21
+#define ISR22   22
+#define ISR23   23
+#define ISR24   24
+#define ISR25   25
+#define ISR26   26
+#define ISR27   27
+#define ISR28   28
+#define ISR29   29
+#define ISR30   30
+#define ISR31   31
+
+#define IRQ0    32
+#define IRQ1    33
+#define IRQ2    34
+#define IRQ3    35
+#define IRQ4    36
+#define IRQ5    37
+#define IRQ6    38
+#define IRQ7    39
+#define IRQ8    40
+#define IRQ9    41
+#define IRQ10   42
+#define IRQ11   43
+#define IRQ12   44
+#define IRQ13   45
+#define IRQ14   46
+#define IRQ15   47
+
+#define NR_IRQS 48
 
 /****************************************************************************
  * Public Types
diff --git a/nuttx/arch/x86/src/i486/up_assert.c b/nuttx/arch/x86/src/i486/up_assert.c
index 77d6ca3ba..e9be9bcfc 100644
--- a/nuttx/arch/x86/src/i486/up_assert.c
+++ b/nuttx/arch/x86/src/i486/up_assert.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * arch/x86/src/i486/up_assert.c
  *
- *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   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
diff --git a/nuttx/arch/x86/src/qemu/Make.defs b/nuttx/arch/x86/src/qemu/Make.defs
index 5793ecd09..0010f3f3e 100755
--- a/nuttx/arch/x86/src/qemu/Make.defs
+++ b/nuttx/arch/x86/src/qemu/Make.defs
@@ -50,7 +50,7 @@ CMN_CSRCS	= up_allocateheap.c up_assert.c up_blocktask.c up_copystate.c \
 
 # Required QEMU files
 
-CHIP_ASRCS	= qemu_saveusercontext.S qemu_fullcontextrestore.S
+CHIP_ASRCS	= qemu_saveusercontext.S qemu_fullcontextrestore.S qemu_vectors.S
 CHIP_CSRCS	= qemu_idle.c qemu_irq.c qemu_lowputc.c qemu_lowsetup.c \
 			  qemu_timerisr.c
 
diff --git a/nuttx/arch/x86/src/qemu/qemu_head.S b/nuttx/arch/x86/src/qemu/qemu_head.S
index 9d436b4fd..cf754408f 100755
--- a/nuttx/arch/x86/src/qemu/qemu_head.S
+++ b/nuttx/arch/x86/src/qemu/qemu_head.S
@@ -40,20 +40,37 @@
 #include <nuttx/config.h>

 

 /****************************************************************************

- * .text

+ * Pre-processor definitions

+ ****************************************************************************/

+ 

+/* Memory Map: _sbss is the start of the BSS region (see ld.script) _ebss is

+ * the end of the BSS regsion (see ld.script). The idle task stack starts at

+ * the end of BSS and is of size CONFIG_IDLETHREAD_STACKSIZE.  The IDLE thread

+ * is the thread that the system boots on and, eventually, becomes the idle,

+ * do nothing task that runs only when there is nothing else to run.  The

+ * heap continues from there until the end of memory.  See g_heapbase below.

+ */

+

+#define STACKBASE	((_ebss + 0x1f) & 0xffffffe0)

+#define IDLE_STACK	(STACKBASE+CONFIG_IDLETHREAD_STACKSIZE)

+#define HEAP_BASE	(STACKBASE+CONFIG_IDLETHREAD_STACKSIZE)

+

+/****************************************************************************

+ * Nasm .text

  ****************************************************************************/

 

 #ifdef CONFIG_X86_NASM

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

-extern		os_start					/* os_start is defined elsewhere */

-extern		up_lowsetup					/* up_lowsetup is defined elsewhere */

+global		_g_heapbase					/* The start of the heap */

+extern		_os_start					/* os_start is defined elsewhere */

+extern		_up_lowsetup				/* up_lowsetup is defined elsewhere */

  

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

 

 MODULEALIGN	equ	1<<0					/* Align loaded modules on page boundaries */

 MEMINFO		equ	1<<1					/* Provide memory map */

 FLAGS		equ	MODULEALIGN | MEMINFO	/* This is the Multiboot 'flag' field */

-MAGIC		equ	0x1BADB002				/* 'magic number' lets bootloader find the header */

+MAGIC		equ	0x1badb002				/* 'magic number' lets bootloader find the header */

 CHECKSUM	equ -(MAGIC + FLAGS)		/* Checksum required */

  

 section .text

@@ -63,63 +80,129 @@ MultiBootHeader:
 	dd		FLAGS

 	dd		CHECKSUM

  

-/* Reserve initial kernel stack space */

-

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

- 

 __start:

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

+	/* Set up the stack */

+

+	mov		esp, idle_stack + CONFIG_IDLETHREAD_STACKSIZE

+

+	/* Multiboot setup */

+

 	push	eax							/* Pass Multiboot magic number */

 	push	ebx							/* Pass Multiboot info structure */

+

+	/* Initialize and start NuttX */

+

+	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 */

- 

+	/* NuttX will not return */

+

 	cli

 hang:

 	hlt									/* Halt machine should NuttX return */

 	jmp		hang

  

+/****************************************************************************

+ * .bss

+ ****************************************************************************/

+

+/* The stack for the IDLE task thread is declared in .bss.  NuttX boots and

+ * initializes on the IDLE thread, then at the completion of OS startup, this

+ * thread becomes the thread that executes when there is nothing else to

+ * do in the system (see up_idle()).

+ */

+

 section .bss

 align 4

-stack:

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

+idle_stack:

+	resb CONFIG_IDLETHREAD_STACKSIZE

+

+/****************************************************************************

+ * .rodata

+ ****************************************************************************/

+

+section .rodata

+

+/* HEAP BASE: _sbss is the start of the BSS region (see ld.script) _ebss is

+ * the end of the BSS region (see ld.script). The heap continues from there

+ * until the end of memory.

+ */

+

+align 4

+g_heapbase:

+	dd	_ebss

 

 #else /* !CONFIG_X86_NASM (GAS) */

 

+/****************************************************************************

+ * GAS .text

+ ****************************************************************************/

+

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

 	.global	_os_start					/* os_start is defined elsewhere */

 	.global	_up_lowsetup				/* up_lowsetup is defined elsewhere */

+	.global	_g_heapbase					/* The start of the heap */

 

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

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

 

 	.set	ALIGN, 1<<0					/* Align loaded modules on page boundaries */

 	.set	MEMINFO, 1<<1				/* Provide memory map */

 	.set	FLAGS, ALIGN | MEMINFO		/* This is the Multiboot 'flag' field */

-	.set	MAGIC, 0x1BADB002			/* 'magic number' lets bootloader find the header */

+	.set	MAGIC, 0x1badb002			/* 'magic number' lets bootloader find the header */

 	.set	CHECKSUM, -(MAGIC + FLAGS)	/* Checksum required */

 

+	.text

 	.align	4

 	.long	MAGIC

 	.long	FLAGS

 	.long	CHECKSUM

 

-/* Reserve initial kernel stack space */

+__start:

+	/* Set up the stack */

 

-	.set	STACKSIZE, 0x4000			/* That is, 16k */

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

+	mov		$(idle_stack + CONFIG_IDLETHREAD_STACKSIZE), %esp

+

+	/* Multiboot setup */

 

-__start:

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

 	push	%eax						/* Multiboot magic number */

 	push	%ebx						/* Multiboot data structure */

 

+	/* Initialize and start NuttX */

+

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

 	call	_os_start					/* Start NuttX */

 

+	/* NuttX will not return */

+

 	cli

 hang:

 	hlt									/* Halt machine should NuttX return */

 	jmp	hang

+

+/****************************************************************************

+ * .bss

+ ****************************************************************************/

+

+/* The stack for the IDLE task thread is declared in .bss.  NuttX boots and

+ * initializes on the IDLE thread, then at the completion of OS startup, this

+ * thread becomes the thread that executes when there is nothing else to

+ * do in the system (see up_idle()).

+ */

+

+	.comm   idle_stack, CONFIG_IDLETHREAD_STACKSIZE, 32

+

+/****************************************************************************

+ * .rodata

+ ****************************************************************************/

+

+	.section	.rodata, "a"

+

+/* HEAP BASE: _sbss is the start of the BSS region (see ld.script) _ebss is

+ * the end of the BSS region (see ld.script). The heap continues from there

+ * until the end of memory.

+ */

+

+_g_heapbase:

+	.word	_ebss

 	.end

 #endif /* CONFIG_X86_NASM */
\ No newline at end of file
diff --git a/nuttx/arch/x86/src/qemu/qemu_lowputc.c b/nuttx/arch/x86/src/qemu/qemu_lowputc.c
index 16d4425cc..4e3471e60 100644
--- a/nuttx/arch/x86/src/qemu/qemu_lowputc.c
+++ b/nuttx/arch/x86/src/qemu/qemu_lowputc.c
@@ -67,6 +67,14 @@
 
 void up_lowputc(char ch)
 {
+  /* Wait until the BIOS can accept another character (so that the OS will
+   * continue to run.
+   */
+
+  while ((inb(0x3f8+5) & (1 << 5)) == 0);
+
+  /* Then output the character */
+
   outb(ch, 0x3f8);
 }
 
diff --git a/nuttx/arch/x86/src/qemu/qemu_lowsetup.c b/nuttx/arch/x86/src/qemu/qemu_lowsetup.c
index ef48f0e7b..aac19042d 100644
--- a/nuttx/arch/x86/src/qemu/qemu_lowsetup.c
+++ b/nuttx/arch/x86/src/qemu/qemu_lowsetup.c
@@ -57,6 +57,57 @@
  ****************************************************************************/
 
 /****************************************************************************
+ * Name: up_gdtentry
+ *
+ * Description:
+ *   Set the value of one GDT entry.
+ *
+ ****************************************************************************/
+
+static void up_gdtentry(struct gdt_entry_s *entry, uint32_t base,
+                        uint32_t limit, uint8_t access, uint8_t gran)
+{
+  entry->lowbase      = (base & 0xffff);
+  entry->midbase      = (base >> 16) & 0xff;
+  entry->hibase       = (base >> 24) & 0xff;
+
+  entry->lowlimit     = (limit & 0xffff);
+  entry->granularity  = (limit >> 16) & 0x0f;
+    
+  entry->granularity |= gran & 0xf0;
+  entry->access       = access;
+}
+
+/****************************************************************************
+ * Name: up_gdtinit
+ *
+ * Description:
+ *   Initialize the GDT. The Global Descriptor Table or GDT is a data
+ *   structure used by Intel x86-family processors starting with the 80286
+ *   in order to define the characteristics of the various memory areas used
+ *   during program execution, for example the base address, the size and
+ *   access privileges like executability and writability. These memory areas
+ *   are called segments in Intel terminology.
+ *
+ ****************************************************************************/
+
+static void up_gdtinit(void)
+{
+  struct gdt_entry_s gdt_entries[5];
+  struct gdt_ptr_s   gdt_ptr;
+
+  up_gdtentry(0, 0, 0, 0, 0);                /* Null segment */
+  up_gdtentry(1, 0, 0xffffffff, 0x9a, 0xcf); /* Code segment */
+  up_gdtentry(2, 0, 0xffffffff, 0x92, 0xcf); /* Data segment */
+  up_gdtentry(3, 0, 0xffffffff, 0xfa, 0xcf); /* User mode code segment */
+  up_gdtentry(4, 0, 0xffffffff, 0xf2, 0xcf); /* User mode data segment */
+
+  gdt_ptr.limit = (sizeof(struct gdt_entry_s) * 5) - 1;
+  gdt_ptr.base  = (uint32_t)gdt_entries;
+  gdt_flush((uint32_t )&gdt_ptr);
+}
+
+/****************************************************************************
  * Public Functions
  ****************************************************************************/
 
diff --git a/nuttx/arch/x86/src/qemu/qemu_vectors.S b/nuttx/arch/x86/src/qemu/qemu_vectors.S
new file mode 100755
index 000000000..93cac4b3d
--- /dev/null
+++ b/nuttx/arch/x86/src/qemu/qemu_vectors.S
@@ -0,0 +1,395 @@
+/****************************************************************************
+ *  arch/x86/src/qemu/qemu_head.S
+ *
+ *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ *   Based on Bran's kernel development tutorials. Rewritten for JamesM's
+ *   kernel development tutorials.
+ *
+ * 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/irq.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define KSEG 0x10
+
+/****************************************************************************
+ * Nasm .text
+ ****************************************************************************/
+
+#ifdef CONFIG_X86_NASM
+extern _irq_handler
+extern _isr_handler
+
+/* Trace macros, use like trace 'i' to print char to serial port. */
+
+%macro	io_outb 2
+	mov		dx, %1				/* param1 = address, param2 = data. */
+	mov		al, %2
+	out		dx, al
+%endmacro
+
+%macro  trace 1
+	io_outb	0x3f8, %1			/*  diagnostic character */
+%endmacro
+
+/* This macro creates a stub for an ISR which does NOT pass it's own
+ * error code (adds a dummy errcode byte).
+ */
+
+%macro ISR_NOERRCODE 1
+  global	vector_isr%1
+  vector_isr%1:
+	cli							/* Disable interrupts firstly. */
+	push	byte 0				/* Push a dummy error code. */
+	push	byte %1				/* Push the interrupt number. */
+	jmp		isr_common			/* Go to our common handler code. */
+%endmacro
+
+/* This macro creates a stub for an ISR which passes it's own
+ * error code.
+ */
+
+%macro ISR_ERRCODE 1
+  global	vector_isr%1
+  vector_isr%1:
+	cli							/* Disable interrupts. */
+	push	byte %1				/* Push the interrupt number */
+	jmp		isr_common
+%endmacro
+
+/* This macro creates a stub for an IRQ - the first parameter is
+ * the IRQ number, the second is the ISR number it is remapped to.
+ */
+
+%macro IRQ 2
+  global	vector_irq%1
+  vector_irq%1:
+	cli
+	push	byte 0
+	push	byte %2
+	jmp		irq_common
+%endmacro
+		
+/* The following will be the vector address programmed into the IDT */
+
+ISR_NOERRCODE		ISR0
+ISR_NOERRCODE		ISR1
+ISR_NOERRCODE		ISR2
+ISR_NOERRCODE		ISR3
+ISR_NOERRCODE		ISR4
+ISR_NOERRCODE		ISR5
+ISR_NOERRCODE		ISR6
+ISR_NOERRCODE		ISR7
+ISR_ERRCODE			ISR8
+ISR_NOERRCODE		ISR9
+ISR_ERRCODE			ISR10
+ISR_ERRCODE			ISR11
+ISR_ERRCODE			ISR12
+ISR_ERRCODE			ISR13
+ISR_ERRCODE			ISR14
+ISR_NOERRCODE		ISR15
+ISR_NOERRCODE		ISR16
+ISR_NOERRCODE		ISR17
+ISR_NOERRCODE		ISR18
+ISR_NOERRCODE		ISR19
+ISR_NOERRCODE		ISR20
+ISR_NOERRCODE		ISR21
+ISR_NOERRCODE		ISR22
+ISR_NOERRCODE		ISR23
+ISR_NOERRCODE		ISR24
+ISR_NOERRCODE		ISR25
+ISR_NOERRCODE		ISR26
+ISR_NOERRCODE		ISR27
+ISR_NOERRCODE		ISR28
+ISR_NOERRCODE		ISR29
+ISR_NOERRCODE		ISR30
+ISR_NOERRCODE		ISR31
+IRQ				 0,	IRQ0
+IRQ				 1,	IRQ1
+IRQ 			 2,	IRQ2
+IRQ				 3,	IRQ3
+IRQ				 4,	IRQ4
+IRQ				 5,	IRQ5
+IRQ				 6,	IRQ6
+IRQ				 7,	IRQ7
+IRQ				 8,	IRQ8
+IRQ				 9,	IRQ9
+IRQ				10,	IRQ10
+IRQ				11,	IRQ11
+IRQ				12,	IRQ12
+IRQ				13,	IRQ13
+IRQ				14,	IRQ14
+IRQ				15,	IRQ15
+
+/* This is our common ISR stub. It saves the processor state, sets up for
+ * kernel mode segments, calls the C-level fault handler, and finally restores
+ * the stack frame.
+ */
+
+isr_common:
+/*	trace	'S' */
+	pusha						/* Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax */
+
+	mov		ax, ds				/* Lower 16-bits of eax = ds. */
+	push	eax					/* Save the data segment descriptor */
+
+	mov		ax, KSEG			/* Load the kernel data segment descriptor */
+	mov		ds, ax
+	mov		es, ax
+	mov		fs, ax
+	mov		gs, ax
+
+	call	_isr_handler
+
+	pop		ebx					/* Reload the original data segment descriptor */
+	mov		ds, bx
+	mov		es, bx
+	mov		fs, bx
+	mov		gs, bx
+
+	popa						/* Pops edi,esi,ebp... */
+	add		esp, 8				/* Cleans up the pushed error code and pushed ISR number */
+	sti
+	iret						/* Pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP */
+
+/* This is our common IRQ stub. It saves the processor state, sets up for
+ * kernel mode segments, calls the C-level fault handler, and finally restores
+ * the stack frame.
+ */
+
+irq_common:
+/*	trace	'R' */
+	pusha						/* Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax */
+
+	mov		ax, ds				/* Lower 16-bits of eax = ds. */
+	push	eax					/* Save the data segment descriptor */
+
+	mov		ax, KSEG			/* Load the kernel data segment descriptor */
+	mov		ds, ax
+	mov		es, ax
+	mov		fs, ax
+	mov		gs, ax
+
+	call	_irq_handler
+
+	pop		ebx					/* Reload the original data segment descriptor */
+	mov		ds, bx
+	mov		es, bx
+	mov		fs, bx
+	mov		gs, bx
+
+	popa						/* Pops edi,esi,ebp... */
+	add		esp, 8				/* Cleans up the pushed error code and pushed ISR number */
+	sti
+	iret						/* Pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP */
+
+#else /* !CONFIG_X86_NASM (GAS) */
+
+/****************************************************************************
+ * GAS .text
+ ****************************************************************************/
+
+	.globl	_irq_handler
+	.globl	_isr_handler
+
+/* Trace macros, use like trace 'i' to print char to serial port. */
+
+	.macro	io_outb, addr, data
+	mov		dx, $\addr
+	mov		al, $\data
+	out		dx, al
+	.endm
+
+	.macro	trace, ch
+	io_outb	0x3f8, \ch
+	.endm
+
+/* This macro creates a stub for an ISR which does NOT pass it's own
+ * error code (adds a dummy errcode byte).
+ */
+
+	.macro ISR_NOERRCODE, intno
+	.globl	vector_isr\intno
+vector_isr\intno:
+	cli							/* Disable interrupts firstly. */
+	push	$0					/* Push a dummy error code. */
+	push	$\intno				/* Push the interrupt number. */
+	jmp		isr_common			/* Go to the common handler code. */
+	.endm
+
+/* This macro creates a stub for an ISR which passes it's own
+ * error code.
+ */
+
+	.macro	ISR_ERRCODE, intno
+	.globl	vector_isr\intno
+vector_isr\intno:
+	cli							/* Disable interrupts firstly. */
+	push	$\intno				/* Push the interrupt number. */
+	jmp		isr_common			/* Go to the common handler code. */
+	.endm
+
+/* This macro creates a stub for an IRQ - the first parameter is
+ * the IRQ number, the second is the ISR number it is remapped to.
+ */
+
+	.macro	IRQ, irqno, intno
+	.globl	vector_irq\irqno
+vector_irq\irqno:
+	cli							/* Disable interrupts firstly. */
+	push	$0					/* Push a dummy error code. */
+	push	$\intno				/* Push the interrupt number. */
+	jmp		isr_common			/* Go to the common handler code. */
+	.endm
+
+	/* The following will be the vector address programmed into the IDT */
+
+	ISR_NOERRCODE		ISR0
+	ISR_NOERRCODE		ISR1
+	ISR_NOERRCODE		ISR2
+	ISR_NOERRCODE		ISR3
+	ISR_NOERRCODE		ISR4
+	ISR_NOERRCODE		ISR5
+	ISR_NOERRCODE		ISR6
+	ISR_NOERRCODE		ISR7
+	ISR_ERRCODE			ISR8
+	ISR_NOERRCODE		ISR9
+	ISR_ERRCODE			ISR10
+	ISR_ERRCODE			ISR11
+	ISR_ERRCODE			ISR12
+	ISR_ERRCODE			ISR13
+	ISR_ERRCODE			ISR14
+	ISR_NOERRCODE		ISR15
+	ISR_NOERRCODE		ISR16
+	ISR_NOERRCODE		ISR17
+	ISR_NOERRCODE		ISR18
+	ISR_NOERRCODE		ISR19
+	ISR_NOERRCODE		ISR20
+	ISR_NOERRCODE		ISR21
+	ISR_NOERRCODE		ISR22
+	ISR_NOERRCODE		ISR23
+	ISR_NOERRCODE		ISR24
+	ISR_NOERRCODE		ISR25
+	ISR_NOERRCODE		ISR26
+	ISR_NOERRCODE		ISR27
+	ISR_NOERRCODE		ISR28
+	ISR_NOERRCODE		ISR29
+	ISR_NOERRCODE		ISR30
+	ISR_NOERRCODE		ISR31
+	IRQ				 0,	IRQ0
+	IRQ				 1,	IRQ1
+	IRQ 			 2,	IRQ2
+	IRQ				 3,	IRQ3
+	IRQ				 4,	IRQ4
+	IRQ				 5,	IRQ5
+	IRQ				 6,	IRQ6
+	IRQ				 7,	IRQ7
+	IRQ				 8,	IRQ8
+	IRQ				 9,	IRQ9
+	IRQ				10,	IRQ10
+	IRQ				11,	IRQ11
+	IRQ				12,	IRQ12
+	IRQ				13,	IRQ13
+	IRQ				14,	IRQ14
+	IRQ				15,	IRQ15
+
+/* This is our common ISR stub. It saves the processor state, sets up for
+ * kernel mode segments, calls the C-level fault handler, and finally restores
+ * the stack frame.
+ */
+
+isr_common:
+/*	trace	'S' */
+	pusha						/* Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax */
+
+	mov		%ax, ds				/* Lower 16-bits of eax = ds. */
+	pushl	%eax				/* Save the data segment descriptor */
+
+	mov		%ax, KSEG			/* Load the kernel data segment descriptor */
+	mov		ds, %ax
+	mov		es, %ax
+	mov		fs, %ax
+	mov		gs, %ax
+
+	call	_isr_handler
+
+	pop		ebx					/* Reload the original data segment descriptor */
+	mov		ds, %bx
+	mov		es, %bx
+	mov		fs, %bx
+	mov		gs, %bx
+
+	popa						/* Pops edi,esi,ebp... */
+	add		%esp, 8				/* Cleans up the pushed error code and pushed ISR number */
+	sti
+	iret						/* Pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP */
+
+/* This is our common IRQ stub. It saves the processor state, sets up for
+ * kernel mode segments, calls the C-level fault handler, and finally restores
+ * the stack frame.
+ */
+
+irq_common:
+/*	trace	'R' */
+	pusha						/* Pushes edi,esi,ebp,esp,ebx,edx,ecx,eax */
+
+	mov		%ax, ds				/* Lower 16-bits of eax = ds. */
+	push	%eax				/* Save the data segment descriptor */
+
+	mov		%ax, KSEG			/* Load the kernel data segment descriptor */
+	mov		ds, %ax
+	mov		es, %ax
+	mov		fs, %ax
+	mov		gs, %ax
+
+	call	_irq_handler
+
+	pop		%ebx				/* Reload the original data segment descriptor */
+	mov		ds, %bx
+	mov		es, %bx
+	mov		fs, %bx
+	mov		gs, %bx
+
+	popa						/* Pops edi,esi,ebp... */
+	add		%esp, 8				/* Cleans up the pushed error code and pushed ISR number */
+	sti
+	iret						/* Pops 5 things at once: CS, EIP, EFLAGS, SS, and ESP */
+	.end
+#endif /* CONFIG_X86_NASM */
diff --git a/nuttx/configs/qemu-i486/ostest/ld.script b/nuttx/configs/qemu-i486/ostest/ld.script
index 0996f5310..209a0089a 100755
--- a/nuttx/configs/qemu-i486/ostest/ld.script
+++ b/nuttx/configs/qemu-i486/ostest/ld.script
@@ -41,6 +41,7 @@ SECTIONS
 	.text : {
 		_stext = ABSOLUTE(.);
 		*(.text .text.*)        
+		*(.gnu.linkonce.t.*)
 		_etext = ABSOLUTE(.);
 	}
 
@@ -49,7 +50,6 @@ SECTIONS
 		*(.rodata .rodata.*)        
 		*(.fixup)
 		*(.gnu.warning)
-		*(.gnu.linkonce.t.*)
 		*(.glue_7)
 		*(.glue_7t)
 		*(.got)
@@ -74,7 +74,7 @@ SECTIONS
 		_ebss = ABSOLUTE(.);
 	}
 
-	/* Stabs debugging sections.	*/
+	/* Stabs debugging sections */
 	.stab 0 : { *(.stab) }
 	.stabstr 0 : { *(.stabstr) }
 	.stab.excl 0 : { *(.stab.excl) }