MCTP Daemon

This component implements MCTP Base Specification DSP0236(MCTP Base Specification), DSP0237(MCTP SMBus/I2C Transport Binding Specification) and DSP0238(MCTP PCIe VDM Transport Binding Specification).

Overview

MCTP service is responsible for discovering endpoints in the network (either as a bus owner or by querying routing table from bus owner). This also provides mechanisms(D-Bus methods) for upper layer applications to transmit and receive MCTP packets.

MCTP Over SMBus support(As MCTP bus owner)

Supports

1. Seperate instances on different physical bus
2. Device discovery
3. Hotplug device discovery
4. 'Pull Model - Support to initiate MCTP message for an endpoint' MCTP message support
5. Device watcher to handle rogue/buggy device
6. MCTP supported device list filter

Assumptions

1. Bus Owners to have a statically allocated pool of EIDs
2. SMBus ARP Master is out of scope for this document
3. PLDM, Intel Vendor Defined Messages and other MCTP Message Types are out of scope

Device Discovery

BMC takes statically configurations(EID pool, bus path etc..) exposed by entity-manager or by JSON file. BMC scans those buses for MCTP capable devices and executes the bus owner responsibilities of EID assignment and device capability discovery.

MCTP Control Commands Supported on SMBus Binding

MCTP Control command	Command Code	Requester	Responder	Comments
Set Endpoint ID	0x01	Supported	N/A	Allocated Endpoint IDs to MCTP Endpoints. Allocation of pool to bridges is not supported. Clause 12.3 in DPS0236 v1.3.0
Get Endpoint ID	0x02	Supported	Supported	Generates and responds to Get EID command. Clause 12.4 in DPS0236 v1.3.0
Get Endpoint UUID	0x03	Supported	N/A	Queries a device’s UUID available in the same network. Clause 12.5 in DPS0236 v1.3.0
Get MCTP Version Support	0x04	Supported	Supported	Clause 12.6 in DPS0236 v1.3.0
Get Message Type Support	0x05	Supported	Supported	Clause 12.7 in DPS0236 v1.3.0
Get Vendor Defined Message Support	0x06	Supported	Supported	Clause 12.8 in DPS0236 v1.3.0

I2C Multiplexer Support

BMC needs to keep the I2C Mux channel open for the endpoint devices to send the responses. In addition, "pull model" MCTP message support(Mux channels need to be opened for MCTP messages originating from the endpoint to reach BMC) is implemented using ReserveBandwidth and ReleaseBandwidth D-Bus method calls (Usecase: PLDM firmware update).

MCTP over PCIe VDM(As MCTP endpoint)

Supports

1. Discovery by a bus owner on the PCIe bus
2. MCTP communication with other endpoints on PCIe bus
3. Support for MCTP VDM PCI message format

MCTP Control commands supported in PCIe endpoint

MCTP Control command	Command Code	Requester	Responder	Comments
Set Endpoint ID	0x01	N/A	Supported	Accepts EID set by PCIe Bus Owner. Clause 12.3 in DPS0236 v1.3.0
Get Endpoint ID	0x02	N/A	Supported	Accepts incoming Get EID commands and responds appropriately. Clause 12.4 in DPS0236 v1.3.0
Get Endpoint UUID	0x03	Supported	N/A	Queries a device’s UUID available in the same network. Clause 12.5 in DPS0236 v1.3.0
Get MCTP Version Support	0x04	N/A	Supported	Clause 12.6 in DPS0236 v1.3.0
Get Message Type Support	0x05	Supported	Supported	Support for discovering a device’s MCTP capabilities as well as allow discovery of BMC’s supported MCTP Message Types. Clause 12.7 in DPS0236 v1.3.0
Get Vendor Defined Message Support	0x06	N/A	Supported	Allow discovery of BMC’s supported Vendor Defined MCTP Message Types. Clause 12.8 in DPS0236 v1.3.0
Get Routing Table Entries	0x0A	Supported	N/A	Used for discovery of neighboring MCTP Endpoints. Clause 12.12 in DPS0236 v1.3.0
Prepare for Endpoint Discovery	0x0B	N/A	Supported	Responds to Bus Owner’s prepare for Endpoint Discovery command. Clause 12.13 in DPS0236 v1.3.0
Endpoint Discovery	0x0C	N/A	Supported	Responds to Bus Owner’s Endpoint Discovery command. Clause 12.14 in DPS0236 v1.3.0
Discovery Notify	0x0D	Supported	N/A	Clause 12.15 in DPS0236 v1.3.0

Standalone Build

To build the package do the following

1. mkdir build
2. cd build
3. cmake -DBUILD_STANDALONE=ON -DMCTPD_BUILD_UT=ON ../
4. make

TODO Items

1. MCTP bridging