PCIR_SUBBUS_1
sc->subbus = pci_read_config(dev, PCIR_SUBBUS_1, 1);
pci_write_config(dev, PCIR_SUBBUS_1, 0xa, 1);
sc->subbus = pci_read_config(dev, PCIR_SUBBUS_1, 1);
print_bus_range(fd, p, PCIR_SECBUS_1, PCIR_SUBBUS_1);