PiBox

Instead of calling reboot which will take the hardware back to the bootloader, it would be faster (and probably cleaner appearing) to use kexec.

1. Enable kexec in Buildroot: Target Packages->Debugging, Profiling and Benchmarking
2. Have S99zzreboot call rcK to shutdown everything
   1. Don't umount the squashfs however - it provides access to the kexec command. This might be possible to copy to a tmpfs before unmounting everything and then running it from the tmpfs.
3. Setup and run kexec

This would prevent the RPi 7" touchscreen from going into it's weird reboot mode (I think) and, more importantly, would be useful to Xeon to not have to hold down the volume down button on firstboot. Note that this will need to be manually migrated to Xeon after testing on PiBox builds.