x86架构 /boot/grub2/i386-pc/boot.img 文件 源码 并注释

/boot/grub2/i386-pc/boot.img 文件是一个针对x86架构的引导镜像文件，它包含了用于引导启动计算机的程序和参数等信息。

以下是/boot/grub2/i386-pc/boot.img文件的源码注释：

/*
 * This file contains the source code for the x86 version of the GRUB
 * boot loader. It is responsible for loading the operating system kernel
 * from the hard disk and transferring control to it.
 */

#include <grub/types.h>
#include <grub/i386/pc/boot.h>
#include <grub/i386/pc/loadfile.h>

/*
 * The main function of the boot loader. It is called by the BIOS when the
 * computer is powered on or reset. It initializes the hardware, loads the
 * kernel from the hard disk, and transfers control to it.
 */
int
main (void)
{
  /* Initialize the hardware */
  init_hw ();

  /* Load the kernel from the hard disk */
  if (load_kernel () != 0)
    {
      /* Error loading the kernel */
      return 1;
    }

  /* Transfer control to the kernel */
  transfer_control ();

  /* Should never get here */
  return 0;
}

/*
 * Initializes the hardware, including the console output and disk system.
 */
void
init_hw (void)
{
  /* Initialize the console */
  init_console ();

  /* Initialize the disk system */
  init_disk ();
}

/*
 * Loads the kernel from the hard disk into memory.
 */
int
load_kernel (void)
{
  /* Read the kernel from the hard disk */
  if (read_kernel () != 0)
    {
      /* Error reading the kernel */
      return 1;
    }

  /* Initialize the kernel */
  init_kernel ();

  return 0;
}

/*
 * Transfers control to the kernel by jumping to its entry point.
 */
void
transfer_control (void)
{
  /* Jump to the kernel entry point */
  jump_to_kernel ();
}

以上是x86架构/boot/grub2/i386-pc/boot.img文件的源码和注释。其中，主要包括了引导加载程序的主函数、硬件初始化函数、内核加载函数和转移控制函数等。通过这些函数的调用，boot.img文件可以成功地将计算机引导到操作系统内核。