title: Creating a clean root filesystem (with overlay) without rebuilding all the packages
body: <p>I currently have a buildroot configuration that outputs a U-Boot-wrapped root filesystem. Part of that process overlays files from a outside directory, which contains things like network interfaces, profile.d scripts, and some custom executables.</p>
  
  <p>My question is this: what is the best way to recreate the root filesystem image, without rebuilding all the extra packages? Just deleting the output/images and output/target directories, followed by a "make all" doesn't seem to work. For the most common usage, I don't need to rebuild the toolchain, or any other packages. I just need the root filesystem recreated, with the overlay performed. However, there doesn't seem to be a good make target to do a clean on the output only, or a build of the target filesystem/images.</p>
  
  <p>Thanks, </p>
  
  <p>-D</p>