fork1
error = fork1(&lwp0, RFFDG | RFPROC, &initproc);
error = fork1(lp, RFFDG | RFPROC | RFPGLOCK, &p2);
error = fork1(lp, RFFDG | RFPROC | RFPPWAIT | RFMEM | RFPGLOCK, &p2);
error = fork1(lp, uap->flags | RFPGLOCK, &p2);
error = fork1(&lwp0, RFMEM | RFFDG | RFPROC | flags, &p2);
int fork1 (struct lwp *, int, struct proc **);