apic_read
data = apic_read(r, APIC_VERSION);
printf("0x%04x 0x%04x\n", apic_read(sc->sc_regs, APIC_ENT0(i)),
apic_read(sc->sc_regs, APIC_ENT1(i)));
uint32_t apic_read(volatile struct elroy_regs *, uint32_t reg);