Marcus Folkesson

br2-readonly-rootfs-overlay This is a Buildroot external module that could be used as a reference design when building your own system with an overlayed root filesystem. It's created as an external module to make it easy to adapt for your to your own application. The goal is to achieve the same functionality I have in meta-readonly-rootfs-overlay [1] but for Buildroot. Why does this exists? Having a read-only root file system is useful for many scenarios:

Test packages in Buildroot When writing packages for Buildroot there are several conditions that you have to test your package against. This includes different toolchains, architectures, C-libraries, thread-implementations and more. To help you with that, Buildroot provides the utils/test-pkg script. Nothing describes the script better than its own help text [1]: test-pkg: test-build a package against various toolchains and architectures The supplied config snippet is appended to each toolchain config, the resulting configuration is checked to ensure it still contains all options specified in the snippet; if any is missing, the build is skipped, on the assumption that the package under test requires a toolchain or architecture feature that is missing.

Support for CRIU in Buildroot A couple of months ago I started to evaluate [1] CRIU [2] for a project I'm working on. The project itself is using Buildroot to build and generate the root filesystem. Unfortunately, Buildroot lacks support for CRIU so there were some work to do. To write the package was not straight forward. The package is only supported on certain architectures and the utils/test-pkg script failed for a few toolchains.

Buildroot: out-of-tree builds Like the Linux kernel, Buildroot supports building out-of-tree in a very similar way. This could be very useful when you have multiple configurations in the same Buildroot repository that you want to build without interference. Consider the following example: cd buildroot/ mkdir -p ../outputs/device{1,2} make O=../outputs/device1 menuconfig make O=../outputs/device1 make O=../outputs/device2 menuconfig make O=../outputs/device2 Each output has its own .config so you may change the build configurations independently.

config utility for Buildroot I'm using the ./scripts/config script in the Linux kernel tree a lot. The script is used to manipulate a .config file from the command line which is quite nice to be able to do. I use it mostly to enable configurations from a script or as a part of automated tests. Buildroot is also using KBuild as its configuration system so I adapted this script and submitted a patch.