Buildroot-arm

This is a 2013 Buildroot derivative configured to build an ARM toolchain, plus a couple other tools used to dissect firmware from device manufacturers. It includes FMK (firmware modification kit), binwalk, and reveng. This particular set of tools is capable of dissecting a Tenvis JPT3815w firmware, adding a program to it, opening up telnet, and then packaging the firmware back up.

You could use this set of tools, for example, to compile a program written in C or C++, then install this program onto an existing firmware image that you downloaded from the manufacturers website of various embedded products, such as wireless routers, IP Cams, and perhaps others.

The source code is available at:
https://github.com/tongfa/buildroot-arm.