This docker image contains all the necessary tools to build projects for ARM Cortex M and R MCUs using the GCC-ARM embedded toolchain and GNU make. It also includes git and mercurial to fetch the project's sources and it's dependencies.
It is used as a base image for images that build more specific ARM embedded projects, e.g ARM mbed projects, and to build tests and examples for the tooling made for these projects in a CI system.
Since it is primarily used for testing stuff that should work on workstations this image is based on the latest LTS Ubuntu Docker image.