REDZONEADDR
((char *)(l)->l_addr + (REDZONEADDR + VAX_NBPG))
(USPACE - (REDZONEADDR + VAX_NBPG))
uv += REDZONEADDR;
if (sizeof(struct pcb) > REDZONEADDR)
*(struct rpb *)0 = *(struct rpb *)(uvm_lwp_getuarea(&lwp0) + REDZONEADDR);
kvtopte((uintptr_t)uv + REDZONEADDR)->pg_v = 0;