Sun Sep 14 14:49:59 CEST 2014

BBB boot process

Assuming this requires a ttl serial on the on-board J1 connector.

4 RX
5 TX

This is /dev/ttyO0  (ttyO instead of ttyS?  seems arbitrary[5])
See next entry for boot log.

BBB uses U-Boot[2].  It seems that it first tries to boot from MMC0
(external), then MMC1 (internal).  But this[2] says otherwise.

Before running U-Boot, the Sitara boots MMC1 (internal) from ROM by
loading "MLO" file from a 12,16 or 32 bit FAT MBR.

/dev/mmcblk0p1 FAT U-Boot with "MLO" file.
/dev/mmcblk0p2 linux root

What are these?


They are eMMC hardware level partitions.  See[3][4].  Both are empty
on my BBB.

The simplest way to create an SSD boot card seems to be to clone the
eMMC.  I don't have a uSSD available.  Maybe it can boot from USB[6]?

This[7] confirms my impression:

  If the SDCard is present, it will attempt to boot from the SDCard
  FAT partition. If the SDCard isn’t present, it will boot from the
  eMMC FAT partition

[1] http://dave.cheney.net/2013/09/22/two-point-five-ways-to-access-the-serial-console-on-your-beaglebone-black
[2] http://wiki.beyondlogic.org/index.php/BeagleBoneBlack_Boot_Process
[3] http://www.micron.com/~/media/Documents/Products/Software%20Article/SWNL_hardware_vs_software_partitions.pdf
[4] http://www.crashcourse.ca/wiki/index.php/EMMC_on_the_BBB
[5] http://blog.nixpanic.net/2011/02/serial-ports-with-beagleboard-and-newer.html
[6] http://www.embeddedhobbyist.com/debian-tips/beaglebone-black/beaglebone-black-usb-boot/
[7] https://groups.google.com/forum/#!topic/beagleboard/_mOlo6T-70E