There's a Haiku trac ticket for some missing support in termios.h, but it fails to provide a complete list of what is actually missing.

We need this to be further researched, comparing what is in Haiku and what's POSIX required/recommended, which can be found at opengroup.org

http://dev.haiku-os.org/ticket/1989

Once you have identified all of this attach it to the trac ticket.