OSDev.org

Dear all,
I have one question about the behavior of v2/3rd Gen Core processor PCI Express Root Port - 0155 ( where 0155 is the device id for this root port in Intel platform...)

@ platform information:
- OS: Win7 Pro 32bit
- MB: ASUS P8 Z77 VLE Plus
- CPU : Intel(R) Core(TM) i5-3470 CPU @ 3.20GHz

@ phenomenon:
- if one PCIe device is attached(plug) to PCI Express slot 5, then I can see "...v2/3rd Gen Core processor PCI Express Root Port - 0155" in [Device Manager].
- But if no device plug into slot 5, then this root port is absent in [Device Manager]

@ My questions are:

(1) why this root port is "disabled" without device attached ? ( for other pcie root ports, I found it is still present in [Device Manager] even though no device attached ! )

Can I enable it manually in Ex. DOS ?

(2) how to absolutely identify PCIe root port ?

Ex. PCIe root port is the PCI device in which:
a. class code is 0x6( bridge device)
b. PCIe capability exist

Am I correct ?

Thanks !