Terminology

Buildroot is the tool that we use to build the kernel, kernel modules, user tools, and root file system for our Linux RT machines.

The name we give to the artifacts that buildroot generates is "buildroot".  So, we talk about versions of buildroot as if they are releases of a Linux distribution like Red Hat or Ubuntu.  But they are unrelated to any distribution - they are just buildroot artifacts.

The machines and the buildroot running on these machines are critical to the experiment infrastructure at SLAC.  Experiments have very narrow timing requirements.  This is why we use buildroot.  Buildroot allows us to create a minimal kernel and minimal user tools.  So that for example the kernel is not needlessly interrupted to check for a system update when it should be gathering data for the experiment.

Buildroot also allows user to easily apply patches to the kernel.  We apply the Preempt RT (real time) kernel patch.  This patch makes modifications to the kernel such that kernel interruptions are time-bounded.

Links

• Buildroot
• Preempt RT

Why create a new version?

You might want to create a new version of buildroot if you've found a bug in the current version, or if a new feature is needed.  As I write this document, we have discovered three issues with the current buildroot that must be fixed.