The new callback will be usefull when we will implement the support for Windows. The implementation of native serial set_timeout method uses a HANDLER on Windows and we will use the WinSock2 API which has a socket descriptor. Signed-off-by: Claudiu Olteanu <olteanu.claudiu@ymail.com> Signed-off-by: Dirk Hohndel <dirk@hohndel.org>