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gerrit.openbmc.org / openbmc / libmctp / c2def9f30cd41f33df60cd0795b449267e3329c6
commitc2def9f30cd41f33df60cd0795b449267e3329c6[log] [tgz]
authorEd Tanous <ed.tanous@intel.com>Thu Feb 21 08:33:08 2019 -0800
committerJeremy Kerr <jk@ozlabs.org>Wed Mar 13 16:47:34 2019 +0800
tree568c5326da4cb24f624c40fff44c13d47ca14834
parent6328ffb1d466921871368b00967c240b679abbe4 [diff]
core: Fix sequencing number issues

Sequencing in MCTP allows SOM to declare a completely new sequence
number. Also add an implementation that handles messages that are
neither SOM or EOM.

Minor changes from Jeremy Kerr <jk@ozlabs.org>

Signed-off-by: Ed Tanous <ed.tanous@intel.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
2 files changed
tree: 568c5326da4cb24f624c40fff44c13d47ca14834
  1. tests/
  2. utils/
  3. alloc.c
  4. CMakeLists.txt
  5. core.c
  6. libmctp-alloc.h
  7. libmctp-log.h
  8. libmctp-serial.h
  9. libmctp.h
  10. LICENSE
  11. Makefile
  12. Makefile.inc
  13. README.md
  14. 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.

Integration

The libmctp code is intended to be integrated into other codebases by two methods:

  1. as a simple library (libmctp.a), which can be compiled separately and linked into the containing project

  2. as a set of sources to be included into the containing project (either imported, or as a git subtree/submodule)

For (1), you can use the top-level makefile to produce libmtcp.a.

For (2), the Makefile.inc file provides the minimum set of dependencies to either build libmctp.a, or just the actual object files (LIBMCTP_OBS), which you can include into your existing make definitions. You'll want to set LIBMTCP_DIR to refer to the subdirectory that contains that makefile, so we can set the correct paths to sources.

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, ...) (....)

  • MCTP_NO_DEFAULT_ALLOC: do not set default allocator functions (malloc, free, realloc), and require the use of mctp_set_alloc_ops.

TODO

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