Have used Yocto and Buildroot for Freescale board's official images. Cannot recommend buildroot. Buildroot is a poor build system. Perhaps make has spoiled me,

Have used Yocto and Buildroot for Freescale board's official images. Cannot recommend buildroot. Buildroot is a poor build system. Perhaps make has spoiled me, but I expect anything that calls itself a build system to be able to find on its own what needs to be rebuilt. With buildroot, when I changed a component, I either had to explicitly ask for it to be rebuilt (and the explicitly ask the final image to be rebuilt), or explicitly mark the component dirty. The problem with the latter being that it's a one-way action; there's no way to clear the dirty flag without a full clean and rebuild of that component. Made our custom kernel dev work painfully slow. Yocto was simple enough to read about and understand the setup.