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The current version that we use (2019.08) is here.

SLAC specifics

We can't use buildroot (tool) exactly as it comes from its website.  We have a git repo which contains all the SLAC-specific stuff.  The repo is here.  The master branch is not used (as I write this doc).  Instead, the branches are named by the release, e.g. br-2019.08.  This is done because each branch works with only a single version of buildroot (tool).  For example, br-2019.08 works with buildroot-2019.08, but not necessarily any other version.

The SLAC-specific stuff:

• config files for BusyBox, kernel, and buildroot (tool)
  • so you don't have to "make menuconfig" every time you want a new version of buildroot (artifacts)
• Preempt RT patch (big)
• other patches (several)
• pre-rootfs scripts for adding tools, creating users, adding a password to root

The README in the repo is useful, though vague.  I will update it to be more useful.

Note that the BusyBox config file is reset every time a "make clean" is performed in buildroot (tool).  The other config files are preserved.  I plan to fix this.