The build process allows you to use predefined configuration files for the kernel and for BusyBox. This is what you need to do in order to use your own predefined configuration files: 1) First of all you need to have '.config' configuration file. The assumption is that you already know what '.config' file is and how it is used during the kernel & BusyBox build process. Take the '.config', place it in this folder and finally rename the file. The predefined configuration file name is: kernel.config - for kernel (obviously) busybox.config - for BusyBox (what a surprise) 2) Change the corresponding property in the main '.config' (that's the minimal's config file) to value 'true': USE_PREDEFINED_KERNEL_CONFIG - for kernel USE_PREDEFINED_BUSYBOX_CONFIG - for BusyBox 3) That's it. Now during the build process instead of generating default '.config' files, the predefined configuration files will be used, That's particularly useful if you want to experiment with many non-default config options. In this case it's easier to use configuration file instead of using the scripts in order to generate tons of options. Another useful scenario is when you distribute your OS based on 'Minimal Linux Live' and you want to use non-default kernel and/or BusyBox options 'out of the box'.