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/****************************************************************************
* arch/x86/src/qemu/qemu_head.S
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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>
.file "qemu_head.S"
/****************************************************************************
* 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_idle_topstack below.
*/
#define STACKBASE ((_ebss + 0x1f) & 0xffffffe0)
#define IDLE_STACK (STACKBASE+CONFIG_IDLETHREAD_STACKSIZE)
#define HEAP_BASE (STACKBASE+CONFIG_IDLETHREAD_STACKSIZE)
/****************************************************************************
* Macros
****************************************************************************/
/* Trace macros, use like trace 'i' to print char to serial port. */
.macro trace, ch
#ifdef CONFIG_DEBUG
mov $0x3f8, %dx
mov $\ch, %al
out %al, %dx
#endif
.endm
/****************************************************************************
* Global Symbols
****************************************************************************/
.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_idle_topstack /* The start of the heap */
/****************************************************************************
* .text
****************************************************************************/
/****************************************************************************
* Multiboot Header
****************************************************************************/
/* 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 CHECKSUM, -(MAGIC + FLAGS) /* Checksum required */
.text
.align 4
.long MAGIC
.long FLAGS
.long CHECKSUM
/****************************************************************************
* Name: Start
****************************************************************************/
.type __start, @function
__start:
/* Set up the stack */
mov $(idle_stack + CONFIG_IDLETHREAD_STACKSIZE), %esp
/* Multiboot setup */
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
.size __start, . - __start
/****************************************************************************
* .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()).
*/
.type idle_stack, @object
.comm idle_stack, CONFIG_IDLETHREAD_STACKSIZE, 32
.size idle_stack, CONFIG_IDLETHREAD_STACKSIZE
/****************************************************************************
* .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.
*/
.type g_idle_topstack, @object
g_idle_topstack:
.long _ebss
.size g_idle_topstack, . - g_idle_topstack
.end
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