问题如下：
。。。。
INFO: Installing PetaLinux...
*********************************************
WARNING: PetaLinux installation directory: /opt/pkg/petalinux/. is not empty!
*********************************************
Please input "y" to continue to install PetaLinux in that directory?[n]y
INFO: Checking PetaLinux installer integrity...
INFO: Installing PetaLinux SDK to "/opt/pkg/petalinux/."
INFO: Installing aarch64 Yocto SDK to "/opt/pkg/petalinux/./components/yocto/source/aarch64"...
*********************************************
ERROR: Failed to install Yocto SDK for aarch64.
*********************************************
Please refer to the PetaLinux Tools Installation Guide.
Check the troubleshooting guide at the end of that manual, and if you are
unable to resolve the issue please contact customer support with file:
/home/***/Tools/work/petalinux_installation_log
原因之一：
抛开其它博文中普遍提到的：
可参考：https://blog.csdn.net/mcupro/article/details/91973744
1. 需先安装相关库；
2. 切换到bash；
3. 不要使用root模式安装；
等等。
我碰到的一个情况是：系统中还未安装python，并且需要是v2.xx版本。
其实这点，可以从安装fail时的log文件/home/***/Tools/work/petalinux_installation_log
中看到提示（早没想到直接去看看，折腾半天时间。。。）
sudo apt install python
之后重新安装petalinux，注意最好吧原目录中的log文件删掉，最终，成功
。。
INFO: PetaLinux SDK has been installed to /opt/pkg/petalinux/.