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gerrit.openbmc.org / openbmc / obmc-console / d802b11942abc8a4641976e70d567758ef0bbd58
commitd802b11942abc8a4641976e70d567758ef0bbd58[log] [tgz]
authorJoseph Reynolds <joseph-reynolds@charter.net>Mon Apr 20 21:19:15 2020 -0500
committerJoseph Reynolds <joseph-reynolds@charter.net>Mon Apr 20 21:22:41 2020 -0500
tree00b07bccb992002b276161e4f9afe2ea2a9a7994
parent44036f0b5cddc4fb92b24044729de3e136345eb4 [diff]
Add design notes - UART abstraction

This adds notes from an email that explains how to serve more than one
console:
https://lists.ozlabs.org/pipermail/openbmc/2020-March/020819.html

Signed-off-by: Joseph Reynolds <joseph-reynolds@charter.net>
Change-Id: Id6e87c7b0dc421e4e7aa62f74e797ee38f9d3fb3
1 file changed
tree: 00b07bccb992002b276161e4f9afe2ea2a9a7994
  1. conf/
  2. test/
  3. .gitignore
  4. .travis.yml
  5. bootstrap.sh
  6. config.c
  7. configure.ac
  8. console-client.c
  9. console-server.c
  10. console-server.h
  11. console-socket.c
  12. LICENSE
  13. log-handler.c
  14. MAINTAINERS
  15. Makefile.am
  16. README.md
  17. ringbuffer.c
  18. socket-handler.c
  19. tty-handler.c
  20. util.c
README.md

To Build

Note: In addition to a toolchain and autoconf tools, this requires autotools-archive to be installed.

To build this project, run the following shell commands:

./bootstrap.sh
./configure ${CONFIGURE_FLAGS}
make

To fully clean the repository, run:

./bootstrap.sh clean

To Run Server

Running the server requires a serial port (e.g. /dev/ttyS0):

touch obmc-console.conf
./obmc-console-server --config obmc-console.conf ttyS0

To Connect Client

To connect to the server, simply run the client:

./obmc-console-client

To disconnect the client, use the standard ~. combination.

Underlying design

This shows how the host UART connection is abstracted within the BMC as a Unix domain socket.

               +--------------------------------------------------------------------------------------------+
               |                                                                                            |
               |       obmc-console-client      unix domain socket         obmc-console-server              |
               |                                                                                            |
               |     +---------------------+                           +------------------------+           |
               |     | client.2200.conf    |  +---------------------+  | server.ttyVUART0.conf  |           |
           +---+--+  +---------------------+  |                     |  +------------------------+  +--------+-------+
Network    | 2200 +-->                     +->+ @obmc-console.host0 +<-+                        <--+ /dev/ttyVUART0 |   UARTs
           +---+--+  | socket-id = "host0" |  |                     |  | socket-id = "host0"    |  +--------+-------+
               |     |                     |  +---------------------+  |                        |           |
               |     +---------------------+                           +------------------------+           |
               |                                                                                            |
               |                                                                                            |
               |                                                                                            |
               +--------------------------------------------------------------------------------------------+

This supports multiple independent consoles. The socket-id is a unique portion for the unix domain socket created by the obmc-console-server instance. The server needs to know this because it needs to know what to name the pipe; the client needs to know it as it needs to form the abstract socket name to which to connect.