acpi_pcidev_pciroot_bus
if (ACPI_SUCCESS(acpi_pcidev_pciroot_bus(sc->sc_handle, &bus_start))) {
rv = acpi_pcidev_pciroot_bus(ad->ad_handle, &ap->ap_downbus);
ACPI_STATUS acpi_pcidev_pciroot_bus(ACPI_HANDLE, uint16_t *);