uboot启动过程详解 https://blog.csdn.net/weixin_34337265/article/details/91598222?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-9.nonecase&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-9.nonecase https://www.cnblogs.com/heaad/archive/2010/07/17/1779829.html