OpenBMC host console infrastructure

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  1. 366651d log-handler: Set the end of the file as the file size by Marshall Zhan · 4 months ago master
  2. 6498f9f log-handler: fix console logs by Alexander Hansen · 4 months ago
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  4. 85055f9 docs/mux-support.md: Fix MD014 warnings by George Liu · 5 months ago
  5. ce3688c docs/mux-support.md: Fix MD040 warnings by George Liu · 5 months ago

obmc-console

To Build

To build this project, run the following shell commands:

meson setup build
meson compile -C build

To test:

dbus-run-session meson test -C build

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
        +---+--+  | console-id = "host0" |  |                     |  |  console-id = "host0"  |  +--------+-------+
            |     |                      |  +---------------------+  |                        |           |
            |     +----------------------+                           +------------------------+           |
            |                                                                                             |
            |                                                                                             |
            |                                                                                             |
            +---------------------------------------------------------------------------------------------+

This supports multiple independent consoles. The console-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.

Mux Support

In some hardware designs, multiple UARTS may be available behind a Mux. Please reference docs/mux-support.md in that case.

Sample Development Setup

For developing obmc-console, we can use pseudo terminals (pty's) in Linux.

The socat command will output names of 2 pty's, one of which is the master and the other one is the slave. The master pty can be used to emulate a UART.

$ socat -d -d pty,raw,echo=0,link=pty1 pty,raw,echo=0,link=pty2

$ obmc-console-server --console-id dev $(realpath pty2)

$ obmc-console-client -i dev

# this message should appear for the client
$ echo "hi" > pty1