Undefined reference to `writev'

Hi guys, I managed to compile and upload the Zenoh protocol to a TI CC2538 board. However I had to comment out a vital line of code. The compiler could not detect the “writev” function, i.e. "int n = writev(sock, iov, iovcnt); "

Any ideas on how to solve this issue. Is there a USEMODULE I could apply?