How to differentiate PF vs VF in Intel 82599?

Question

I was trying to understand ixgbevf and ixbge driver. My question How can I differentiate PF device vs VF device by reading PCI configuration space.

Answer 1

You can differentiate PF or VF by reading 2byte from offset 0x0 of the Configuration Space of the Function. There is Vendor ID at offset 0x0.

PF returns 0x8086 for Vendor ID, and VF returns 0xFFFF for Vendor ID.

You can see Intel 82599 Datasheet here. Register maps of PF are from Section 9.3, and Register maps of VF are from Section 9.5.