pcb_fsd
memcpy(&pcb->pcb_fsd, &gdtstore[GUDATA_SEL], sizeof(pcb->pcb_fsd));
(union descriptor *)&pcb->pcb_fsd);
memcpy(&pcb->pcb_fsd, &gdtstore[GUDATA_SEL], sizeof(pcb->pcb_fsd));
memcpy(&fsd, &pcb->pcb_fsd, sizeof(fsd));
struct segment_descriptor pcb_fsd; /* %fs descriptor */
memcpy(&pcb->pcb_fsd, &usd.sd,
sd = (void *)&curpcb->pcb_fsd;