Logging for ser2net

mer. 22 juin 2016 by Rémi Duraffort

Today, I was debugging an strange issue in LAVA while trying to boot a board.

I was under the impression that the board was not receiving all the u-boot commands that LAVA was sending.

The serial connection is accessible on the network by ser2net.

I discovered that ser2net can log inputs, outputs or both to a file:

TRACEFILE:trace1:/var/log/ser2net.2000.log
2000:telnet:0:/dev/ttyUSB0:9600 tr=trace1

ser2net will print both inputs and outputs characters to /var/log/ser2net.2000.log.

Going back to my issue, the logfile was:

sseetteennvv  aauuttoollooaadd  nnoo
sseettenv initrd_high '0xffffffff'

When the characters are doubled, it means that ser2net has sent and received that character. That's what I was expected as the board is supposed to echo all characters.

However, the characters are suddenly no longer doubled: the board is not echoing. This does explain why the board was not booting.

The question remains: why is the serial line breaking after a random number of characters.