The U-Boot boot loader running in the target board is able to write files to the Flash memory of the module. A TFTP server is required to transport these files via Ethernet from the host computer to the target.
Debian-like distributions users can execute the following command to install a TFTP server:
$ apt-get install tftpd-hpa
After completing installation, create a directory /tftpboot where exported files will be located (only root user can create this directory). Images can be placed in the directory automatically by Digi Embedded Linux build environment. Activate all the permissions of this folder.
$ mkdir /tftpboot $ chmod 1777 /tftpboot
To make sure the TFTP server is using the /tftpboot directory, edit the daemon's configuration file /etc/default/tftpd-hpa. Change the constant TFTP_DIRECTORY to point to your recently created /tftpboot folder:
# /etc/default/tftpd-hpa TFTP_USERNAME="tftp" TFTP_DIRECTORY="/tftpboot" TFTP_ADDRESS="0.0.0.0:69" TFTP_OPTIONS="--secure"
Restart the daemon so that it uses the new TFTP folder:
$ sudo service tftpd-hpa restart tftpd-hpa start/running, process 3297