Linux系统启动流程

挖坑，待填

1. http://www.ruanyifeng.com/blog/2013/02/booting.html
2. http://www.ruanyifeng.com/blog/2013/08/linux_boot_process.html
3. https://www.linuxidc.com/Linux/2017-08/146494.htm
4. https://www.ibm.com/developerworks/cn/linux/1407_liuming_init3/index.html