The embedded platform we’ve built for firmware at Oxide is called Hubris. It’s unusual for a microcontroller operating system, and probably the biggest thing that makes it unusual is its use of separately-compiled tasks.

Most firmware applications mash all of their task and OS code together in a common memory space, which is simple and efficient, but can lead to subtle bugs. Hubris instead places bits of code in their own isolated memory areas, where they can run (and crash!) separately. This requires that each bit be compiled as a standalone program.

The CPUs we target don’t have virtual memory, so each of these separate programs has to be laid out at a known place in the address space. This introduces some challenges, and has prevented us from “just” using an off-the-shelf build system.

This post will walk through the process of building a Hubris application from source, from the perspective of the build system, and examine some of these challenges and how we addressed them.