老版本内核源码：
- https://mirrors.edge.kernel.org/pub/linux/kernel/Historic/old-versions/
内核源码分析开源项目：
- https://github.com/ultraji/linux-0.12/tree/master/src
- https://gitee.com/wslyx/linux-0.12
- https://github.com/0voice/linux_kernel_wiki
- https://github.com/ultraji/linux-0.12
