安装的Fedora自带的mkimage打包镜像的时候报错了。于是下载最新的u-boot源码，编译
$ tar xf u-boot-2021.07-rc3.tar.bz2
$ make qemu-x86_64_defconfig
$ make tools
需要安装python开发库
$ sudo dnf install python3-devel
参考
https://stackoverflow.com/questions/63996205/how-to-install-uboot-tools-in-centos-8