idt                12 trap.c         struct gatedesc idt[256];
idt                23 trap.c             SETGATE(idt[i], 0, SEG_KCODE<<3, vectors[i], 0);
idt                24 trap.c           SETGATE(idt[T_SYSCALL], 1, SEG_KCODE<<3, vectors[T_SYSCALL], DPL_USER);
idt                32 trap.c           lidt(idt, sizeof(idt));