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gerrit.openbmc.org / openbmc / libmctp / 24db71fbb553c056f887be1eaafd10e2c7dd1f3f
commit24db71fbb553c056f887be1eaafd10e2c7dd1f3f[log] [tgz]
authorJeremy Kerr <jk@ozlabs.org>Thu Feb 07 21:37:35 2019 +0800
committerJeremy Kerr <jk@ozlabs.org>Fri Feb 08 10:03:00 2019 +0800
tree93085934115f887f77feacef79d06cabf0973a59
parent73d8bc801d7470da3674456d0b7c97f7ff82ec60 [diff]
core: implement packetisation and reassembly

Add a naive implementation of packetisation and reassembly of MCTP
messages. We use a (unbounded!) message buffer for reception, and a
queue of messages for transmission.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
2 files changed
tree: 93085934115f887f77feacef79d06cabf0973a59
  1. tests/
  2. alloc.c
  3. core.c
  4. libmctp-alloc.h
  5. libmctp-log.h
  6. libmctp-serial.h
  7. libmctp.h
  8. Makefile
  9. Makefile.inc
  10. README.md
  11. serial.c
README.md

libmctp: Implementation of MCTP (DTMF DSP0236)

This library is intended to be a portable implementation of the Management Component Transport Protocol (MCTP), as defined by DMTF standard "DSP0236", plus transport binding specifications.

Currently, the library is is only at prototyping stage. Interfaces will likely change, and are missing lots of components of the standard.

Core API

To initialise the MCTP stack with a single hardware bus:

  • mctp = mctp_init(): Initialise the MCTP core
  • binding = mctp_<binding>_init(): Initialise a hardware binding
  • mctp_register_bus(mctp, binding, eid): Register the hardware binding with the core, using a predefined EID

Then, register a function call to be invoked when a message is received:

  • mctp_set_rx_all(mctp, function): Provide a callback to be invoked when a MCTP message is received

Or transmit a message:

  • mctp_message_tx(mctp, message, len): Transmit a MCTP message

The binding may require you to notify it to receive packets. For example, for the serial binding, the mctp_serial_read() function should be invoked when the file-descriptor for the serial device has data available.

Environment configuration

This library is intended to be portable to be used in a range of environments, but the main targets are:

  • Linux userspace, typically for BMC use-cases
  • Low-level firmware environments

For the latter, we need to support customisation of the functions that libmctp uses (for example, POSIX file IO is not available).

In order to support these, we have a couple of compile-time definitions:

  • MCTP_FILEIO: define if POSIX file io is available, allowing the serial hardware binding to access char devices for IO.

  • MCTP_LOG_: allows selection of a logging backend. Currently available are:

    • MCTP_LOG_STDERR: use fprintf(stderr, ...) for log output

    • MCTP_LOG_SYSLOG: use syslog() for log output

    • MCTP_LOG_CUSTOM: provide your own macro for logging, of the format: #define mctp_prlog(level, fmt, ...) (....)

TODO

  • Partial packet queue transmit
  • Control messages
  • Message- and packet-buffer pools and preallocation
  • C++ API
  • Non-file-based serial binding