BusyBox is a key component of most embedded Linux-based projects as it provides an alternative with a smaller footprint when compared to the usual Linux counterparts for the most commonly used utilities. It can be seen as a Swiss knife since it provides a huge set of utilities and is quite flexible regarding which utilities to enable or disable. Poky provides a default setting for BusyBox, and it sometimes may not fulfill our needs; so, changing this configuration is a common task. For example, the <layer>/recipes-core/busybox/busybox_1.22.1.bbappend file could have the following lines of code:

FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" 
SRC_URI += "file://enable-tftpd.cfg" 

The <layer>/recipes-core/busybox/busybox/enable-tftpd.cfg file contains the following:

CONFIG_TFTPD=y 

This combination of the .bbappend file and configuration file is enough to enable support for the TFTP server in BusyBox.