Hey Alex
thanks for the reply. In the meantime I rebuilt the image using the image-full-galileo target and clanton-full to give an eglibc image. This fixes the opencv problem.
The Arduino IDE on Linux doesn't work properly: it will build a sketch fine, but it will not communicate over serial/zmodem with the board. THe sketch will run if you put it on the board manually into /sketch/sketch.elf and make it executable - you have to rebuild the cross compiler toolchain for eglibc using yocto and put that onto your Linux machine but there is an excellent post on this forum which explains how to do that.
I have spent many the hour researching zmodem, and it was not until earlier today that I noticed that the *Windows* Arduino IDE will talk fine to the board over serial. It's just the Linux Arduino IDE which will not.
The problem is that all lsz commands after the first one just time out.
You can replicate this from the command line too. And, for the matter, if you use the OS-provided "sz" command, you get the same behaviour. The first command to the board works (e.g. something like lsz --binary --zmodem --command "yada yada" < /dev/ttyACM0 > /dev/ttyACM0). The second one just times out.
Very peculiar.