error: manifest missing or unreadable -- please run init

due to i made a mistake by deleting .git of kernel , i need recover it . so i found solution here 

https://blog.csdn.net/gh201030460222/article/details/80656513 

in short , i should delete kernel directory and .repo/project-objects/kernel 

then run .repo/repo/repo sync 

we will get what we want.