SYSCALL2(_SysOpen, SYS_OPEN) // char*, int
SYSCALL3(_SysOpenChild, SYS_OPENCHILD) // int, char*, int
SYSCALL3(_SysReopen, SYS_REOPEN) // int, char*, int
+SYSCALL2(_SysCopyFD, SYS_COPYFD) // int, int
SYSCALL1(_SysClose, SYS_CLOSE) // int
SYSCALL3(_SysRead, SYS_READ) // int, uint, void*
SYSCALL3(_SysWrite, SYS_WRITE) // int, uint, void*