ODROID-X2 install UART console driver

You must install specific driver to mount UART USB controller

Refer this page.

http://com.odroid.com/sigong/blog/blog_list.php?bid=128

You should download driver software in http://www.silabs.com/products/interface/usbtouart/Pages/usb-to-uart-bridge.aspx?tab=info

Download below driver file.

CP210x Software package for Linux, includes VCP Drivers

Install it

chmod a+x CP210x_Linux.bin

./CP210x_Linux.bin

After you installed it, you have to see /dev/ttyUSB0 when you connect UART USB controller into your USB port.