_REG_UNIQUE
gr[_REG_UNIQUE] = (unsigned long)private;
gr[_REG_UNIQUE] = (unsigned long)private;
gr[_REG_UNIQUE] = alpha_pal_rdunique();
gr[_REG_UNIQUE] = pcb->pcb_hw.apcb_unique;
lwp_setprivate(l, (void *)(uintptr_t)gr[_REG_UNIQUE]);