OK, I have added the following builtins to klibc: __clone(flags, sp) and on IA64: __clone2(flags, sp, rsp) HOWEVER, these are really not useful to call if sp != NULL, so it's really: __clone(flags, NULL) Since this is the only use supported, I have added an inline for IA64 which calls __clone2() if the user calls __clone(). Note that this is different from the glibc clone()/clone2() wrappers. -hpa