qud

https://alientek-linux.coding.net/public/imx6ull/09_Tutorial_Doc/git/files/master/%E3%80%90%E6%AD%A3%E7%82%B9%E5%8E%9F%E5%AD%90%E3%80%91I.MX6U%E5%B5%8C%E5%85%A5%E5%BC%8FLinux%E9%A9%B1%E5%8A%A8%E5%BC%80%E5%8F%91%E6%8C%87%E5%8D%97V1.6.pdf