I have two USB-serial adapters with a null-modem serial cable between them, similar to this user. I can setup an IP connection easily between two linux (ubuntu) boxes running this pppd command on one side:
pppd -detach crtscts lock 10.2.10.2:10.2.10.2 /dev/ttyUSB0 38400 &
and this on the other:
pppd -detach crtscts lock 10.2.10.1:10.2.10.1 /dev/ttyUSB0 38400 &
However, running the same command between a linux box and an embedded linux device (sama5d3x-mb) I receive the following error message:
Couldn't get channel number: Input/output error
This message can appear on either the desktop linux side or the embedded linux side, it just depends on which end the first command is issued. I also occasionally see this message:
LCP: timeout sending Config-Requests
Obviously something isn't setup correctly in the embedded environment. These are the only error messages that appear in the log.
If I instead open up the serial ports using putty/screen I can tx/rx characters back and forth just fine.
One thing I noticed is that on my desktop system I have a folder at
/etc/ppp that contains many files. Such a folder does not exist on the embedded environment. I tried dumping a copy there with rsync. However, their presence doesn't seem to make a difference.
Both the deskop and embedded platform report
pppd version 2.4.5
Google results mostly turn to dead ends. Short of browsing through the pppd source code, or setting up a sniffer to inspect for any traffic on the lines, I'm sure not where to go from here. Any recommendations?