LAPIC_TPR
lapic_write32(LAPIC_TPR, vector);
tpr = lapic_read32(LAPIC_TPR) & ~APIC_TPR_PRIO;
lapic_write32(LAPIC_TPR, tpr);
db_printf("TPR = %02x\n", lapic_read32(LAPIC_TPR));
lapic_read32(LAPIC_TPR), lapic_read32(LAPIC_SVR));