Davinci DM6446 Linux 内核分析——head.S（一）

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源地址：http://bbs.ivsok.com/blog-2-8.html

//内核解压过程

/*
* linux/arch/arm/boot/compressed/head.S
*
* Copyright (C) 1996-2002 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/config.h>
#include <linux/linkage.h>
/*
* Debugging stuff
*
* Note that these macros must not contain any code which is not
* 100% relocatable. Any attempt to do so will result in a crash.
* Please select one of the following when turning on debugging.
*/

/* 一下是一些调试用的宏。*/
#ifdef DEBUG
#if defined(CONFIG_DEBUG_DC21285_PORT)

/*
这里定义了一个宏，宏名是loadsp，rb是这个宏的参数。宏的参数在宏里被引用时必须加”\”,如：
mov \rb, #0x50000000.
*/
  .macro loadsp, rb
  mov \rb, #0x42000000
  .endm
  .macro writeb, rb
  str \rb, [r3, #0x160]
  .endm
#elif defined(CONFIG_DEBUG_ICEDCC)
  .macro loadsp, rb
  .endm
  .macro writeb, rb
  mcr p14, 0, \rb, c0, c1, 0
  .endm
#elif defined(CONFIG_FOOTBRIDGE)
  .macro loadsp, rb
  mov \rb