termios VMIN VTIME and blocking/non-blocking read operations

Question

I am trying to write a simple C serial communication program for Linux. I am confused about the blocking/non-blocking reads and VMIN/VTIME relationships.

My question

Answer 1

Make sure to unset the FNDELAY flag for descriptor using fcntl, otherwise VMIN/VTIME are ignored. Serial Programming Guide for POSIX Operating Systems