can mctpd be used as an Endpoint?

[rj-sunhui1]

From the documentation, it seems that mctpd is designed to operate only as a bus owner. Is that correct?

[jk-ozlabs]

Yes, mctpd can operate as an endpoint - or even bus owner on some interfaces, and endpoint on others.

From the docs:

Global settings

These apply to all modes of mctpd operation. One top-level setting is defined:

mode: mctpd mode of operation

• type: string enum: bus-owner or endpoint
• default: bus-owner

This sets the overall mode of mctpd, either as a Bus Owner (mode = "bus-owner") or Endpoint (mode = "endpoint"). In bus owner mode, mctpd will
assume responsibility for allocating addresses to other endpoints. In endpoint
mode, mctpd will not allocate addresses, but instead accept allocations from an
external bus owner.

Note that I have a proposed change that renames this to role, but mode will still work.

[rj-sunhui1]

Thank you for your explanation! I have a follow-up question. According to DSP0238, Figure 2 – Flow of Operations for Full MCTP Discovery over PCIe, an endpoint is expected to send a Discovery Notify request to the bus owner as the first step. However, I could not find the corresponding fields or logic in the mctpd code. Is this Discovery Notify request not mandatory to be sent?

[jk-ozlabs]

an endpoint is expected to send a Discovery Notify request to the bus owner as the first step

only on certain transport types.

I haven't needed that for any of the transports I typically deal with, so have not needed the discovery notify so far. Feel free to propose a change!