I've found that this code is not wrong. The problem was from IPC control in thread-ipc.c in sys-ipc() function, the kernel check whether the ipc is next_period() or not, but the check function is wrong i think because the function returns always "FALSE". That means that there is no next_period() ipc. so I've changed the code in shared/entry_frame-ia32-ux.cpp line 110 return false; --> return (_ecx == 0x04000400 && _esi == 0); I'm not sure that this code does not affect to the other ipc. However it is executing quite well. Jungwoo Yang.