General

Question 1

Disabling system error escalation. What is added in svos for RP error checking?

Answer 1

Adding super mon for RP error checking

Question 2

Does error escalation (SYstemError) has impact on error detection ?

Answer 2

No, just won’t get escalated into the system and hang it.

Question 3

Right way to disable aspm l1? Why?

Answer 3

Is better to turn off Aspm L1 from end point, because consumes less Bandwidth

Question 4

What are the buffer sizes for credits at Gen 3, Gen 4 and Gen 5 ?

Answer 4

Is implementation specific but commonly use:
Gen3: 64-Bytes
Gen4: 128 Bytes
Gen5: 256 Bytes

Question 5

How does a Outstanding transaction looks like on RP and EP.

Answer 5

Root Port: Sees the txs as pending transaction until it is knowledge by the EP device.
Endpoint: Once EP has proceed the transaction it returns the Ack (completion status) back to the RP.

Question 6

For a PCIe link what’s a system with segmentation ?

Answer 6

The segmentation allows the expansion and scalability of the PCIe fabric. By adding multiple interconnected switches.

Question 7

Mention the three PCIe accesses space?

Answer 7

MMIO, I/O and Configuration

Question 8

What are the MCTP messages

Answer 8

MCTP are messages of manageability transactions with data

Question 9

How is handled a MemRd and it’s completion originated on the RP?

Answer 9

When travels Downstream the MemRd, there are levels of decoding on switches to route the packet to the correct destination.

Question 10

How a MemRd originated by the EP is handled

Answer 10

The transaction travels Upstream so there is no need to decoding on switches, they just forward tx to the RC.
RC build the completion with ReqID information (ID routing) targeting the correct information routing of the devices requested the tx. The completion goes Downstream

Question 11

For server which are the types of P2P traffic.

Answer 11

Local P2P
Confined P2P
Remote P2P

Question 12

Describe local P2P traffic

Answer 12

The txs within controllers in the same socket.

Question 13

Describe Confined P2P traffic

Answer 13

The EP port 0 is talking to EP port1, etc. between ports on one controller, when a controller/stack is bifurcated

Question 14

What is the remote P2P traffic

Answer 14

An EP in one port on one socket talking to a port in a different socket

Question 15

P2P traffic flows all the way up to the RC?

Answer 15

Not really. Commonly is traveling from one EP through the switch to another target EP.

Question 16

Does the P2P could represent security concerns ?

Answer 16

Yes, but is the reason of ACS mechanism to preserve security

Question 17

Which are the DLLP packet structure?

Answer 17

DLLP -> 4B
CRC -> 2B

Type:
Ack/Nak packets
Flow Control packets
Power management packets
Vendor defined packets