Relevant man pages say that with our previous code libc might return either. Glibc returns tcp but bionic returns udp. So specify it explicitly
uart
This contains functionality for talking to UART/Serial devices on different platforms. The official client will build either uart_posix.c and uart_win32.c. Build targets for these files are contained in client/Makefile.
If you want to implement support for other platforms, you need to implement the methods provided in uart.h.
Implementing a new driver
Each driver is called with a string, typically containing a path or other reference to a serial port on the host. The methods outlined in uart.h need to be implemented.
The hardware uses common/usb_cdc.c to implement a USB CDC endpoint exposed by the Atmel MCU.