The web site: http://eewiki.net/display/linuxonarm/BeagleBone+Black shows the instructions on how to compile from source for BBB. The site is a bit flaky and not all the text
is rendered and displayed (using Firefox!) so I've reproduced it here for
convenience. The only thing I've done it
mde sure the all content is shown. Full credit is attributed to Robert
The BBB boot process is actually a series of steps that can be control based on inputs. Changing the inputs can change how it boots. Just because an SD card inserted does not mean all the boot processes are originating from the SD card.