x86计算机启动过程

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启动流程

  1. BIOS读取MBR(Master Boot record)
  2. MBR引导Bootloader(NTLOADER or GRUB or LILO…)
  3. Bootloader加载kernel
  4. init进程初始化

MBR结构

  • MBR只有512字节大小，存储在硬盘的０道０面１扇区
  • 引导代码（BootCode），446 bytes
  • 分区表（Partition table），64 bytes
  • Magic Number(55AA)，2 bytes
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     -+-  +-------------------+
      |   |                   |
      |   |                   |
      |   |                   |
      |   |                   |
446 B |   |     Boot Code     |
      |   |                   |
      |   |                   |
      |   |                   |                                              
      |   |                   |                                              
     -+-  +-------------------+                                              
      |   |                   |                   +-------------------------+
 64 B |   |     Partition     |                   |        Partition 1      |
      |   |       Table       |   --------->      +-------------------------+
      |   |                   |                   |        Partition 2      | 
     -+-  +-------------------+                   +-------------------------+
      |   |                   |                   |        Partition 3      |
  2 B |   |   Magic Number    |                   +-------------------------+
      |   |                   |                   |        Partition 4      |
     -+-  +-------------------+                   +-------------------------+
                                                                |
                                                                |
                                                                v
                                                                 
           +----------------+-----------+----------------+---------+-----------+------+
           | Partition flag | Start CHS | Partition byte | End CHS | Start LBA | Size |                                  
           +----------------+-----------+----------------+---------+-----------+------+

参考文献