network programming with GHC 7

Hello, When I compiled a network server with GHC 7 without the "-threaded" option and ran it, I got the following error. file descriptor 5496824 out of range for select (0--1024). I have read the paper "Scalable Event Handling for GHC" and understand that this new IO manger assumes the "-threaded" option. Does this mean that we need the "-threaded" option to GHC 7 for networking programming and GHC 7 does not maintain backward compatibility? If so, this should be documented. --Kazu