i am working on iMXS6X-SDB board with our custom linux kernel image version 3.14.28. I have some python reboot tests which gives the reboot command via ssh, waits for some time and this cycle repeats.
While running those tests, when serial port was connected(A9), i saw below log trace on the console before eth1 dropped off the network:
libphy:2188000.ethernet:02 - Link is Down
and the board looks completely in hang state with no ethernet LEDS glowing (orange and Red color -nearby ethernet connector).
Also, serial port looks down - since also i cannot login inside the board to see more information inside dmesg and/or /var/log/messages.
Please let me know if you need any further details. I am not sure why eth1 link drops off after its power cycled multiple times.
This is seen when its power cycled over several hundreds times (though it may fall at any random attempt).
Note- that Sabre board is connected to gigabit ethernet switch and from python (running on PC desktop) is connected to gigabit ethernet switch via USB-gigabit adaptor in between creating a local network.