designs/mctp/mctp-userspace.md

14 The MCTP core specification just provides the packetisation, routing and
20 provides a socket-based interface for other processes to send and receive
24 handling local MCTP-stack configuration, like local EID assignments.
28 1.  the core MCTP stack
30 2.  one or more binding implementations (eg, MCTP-over-serial), which interact
33 3.  an interface to handler applications over a unix-domain socket.
38 - an "upper" messaging transmit/receive interface, for tx/rx of a full message
41 - a "lower" hardware binding for transmit/receive of individual packets,
42   providing a method for the core to tx/rx each packet to hardware, and defines
45 The lower interface would be plugged in to one of a number of hardware-specific
47 tree, but others can be plugged-in too, perhaps where the physical layer
48 implementation does not make sense to include in the platform-agnostic library.
56 for the library should also allow this re-use; a dual Apache & GPLv2+ licence
62 read()/write() syscalls to a PTY device. An I2C binding for use in low-level
66 The application-specific handlers implement the actual functionality provided
71 The daemon's sockets to these handlers is configured for non-blocking IO, to
77 One design intention of the multiplexer daemon is to allow a future kernel-based
79 applications. The socket-based interface facilitates this, as the unix-domain
80 socket interface could be fairly easily swapped out with a new kernel-based
88 MCTP handlers (ie, clients of the demultiplexer) connect using a unix-domain
92 \0mctp-demux
97 Once connected, the client sends a single byte message, indicating what type of
124 implementation contained within a single process, using the libmctp API directly
125 for passing messages from the core code to application-level handlers. The
126 drawback of this approach is that this single process needs to implement all
129 implementation of those application-level handlers (programming language,
130 frameworks used, etc). Also, this single-process approach would likely need more
134 as a socket-based interface. However, an alternative here would be to pass MCTP
136 dbus is that the former allows a direct transition to a kernel-based socket API
141 For the core MCTP library, we are able to run tests there in complete isolation
143 to ensure that the core transport protocol works.
145 For MCTP hardware bindings, we would develop channel-specific tests that would