PCI SBDF value abnormal (bus:Bus:4294967295) get by command "vsish -e get /hardware/pci/seg/0/bus/0/slot/4/func/0/parent"

The PCI SBDF value seems abnormal (Bus = 4294967295?) and it get from "/hardware/pci/seg/0/bus/0/slot/4/func/0/paren"

Does anyone know why this command get the abnormal value?

>> vsish -e get /hardware/pci/seg/0/bus/0/slot/4/func/0/parent

PCI SBDF {

Segment:4294967295

Bus:4294967295

Device:4294967295

Function:4294967295

}