lwp_usermap
lwp_usermap(lp2, 0);
lwp_usermap(lp, -1); /* second arg not yet XXX */
lwp_usermap(lp, -1);
lwp_usermap(lp, -1);
lwp_usermap(lp, -1);
void lwp_usermap(struct lwp *lp, int invfork);