使用arm-none-eabi-5.4版本编译器编译2017.09版本的U-Boot出现了如下问题，怎么解决
gcc: error: unrecognized command line option ‘-mthumb’; did you mean ‘-mtbm’?
gcc: error: unrecognized command line option ‘-mno-unaligned-access’; did you mean ‘-Wno-static-access’?
http://blog.csdn.net/weixin_35695833/article/details/72865487
不知道第三步什么意思