I’m trying to make 2 small changes to the start up process of the Linux build that is put onto the HiFive Unleashed board. 1) I want the startup process to automatically log in the root user and 2) I want to mount the persistent storage partition of the SD card on startup.
Looking around it seems like the best way to accomplish both of these tasks is to make changes to the busybox inittab file (freedom-u-sdk/buildroot/package/busybox/inittab) but any changes I make aren’t picked up by the Makefile which seems to think nothing has changed. Is there a way to force what needs to be rebuilt to rebuild without blowing away huge chunks of the stuff already built?
This style of Makefile relies on stamp files. If the stamp file exists and is newer than the src directory, nothing will be built. Otherwise, the build dir is rm -rf and rebuilt from scratch. Some of the stamp files are . files. You can always cd into the build dir and type make there and this may work. Then, you can then type make at the top level and hopefully it will notice stuff has changed and generate a new image. Otherwise the safe way to update is to remove the appropriate stamp file and just force that build dir to be rebuilt from scratch.
You didn’t mention whether you are using legacy v1_0 branch or current master branch. The legacy v1_0 is what ships with the board, but he current master branch is much more useful. The build process for both is similar though. The current branch has u-boot support, and can be configured to boot into a rootfs on the second partition. It comes with a debian rootfs that can be used for this.