Search for MLO file on Beaglebone Black

Question

I have a Beaglebone Black industrial (BBBI) which I think is very similar to Beaglebone Black.

I want to make BBBI download to the microSD card by default, and I found this guide that suggests deleting the MLOfile from the boot partition. This has been mentioned in several places based on Google, so I guess it's worth a try

In order to rename the file, MLOI tried to find the file using $locateafter downloading without a microSD card, which is supposedly loaded into Debain on eMMC. This gives the following:

/opt/backup/uboot/MLO
/opt/source/pru-software-support-package/pru_cape/bin/MLO
/opt/source/pru-software-support-package/pru_cape/bin/MLO/beaglebone
/opt/source/pru-software-support-package/pru_cape/bin/MLO/beaglebone_black
/opt/source/pru-software-support-package/pru_cape/bin/MLO/beaglebone_black/MLO
/opt/source/pru-software-support-package/pru_cape/bin/MLO/beaglebone/MLO

I double checked that it /bootdoesn’t MLO. Can anyone share where the MLO is located, or did I miss something very obvious?

Alternatively, is there an easier way to boot from a microSD card without pressing the S2 button?

Answer 1

Newer images place MLOs outside of file systems, directly at a few "magic" offsets on the eMMC / SD card. This is described in TRM for the AM335x.

If you don't care about the current contents of eMMC, something like this will do the job brute force:

dd if=/dev/zero of=/dev/mmcblk0 bs=1M count=1
(make sure mmcblk 0 is an eMMC, not an SD card, it changes if you boot from SD and can be mmcblk 1 too)

It destroys the first megabyte of eMMC with zeros. Thus, the partition table and other things also disappeared. Essentially, you get an empty eMMC.

, script /opt/scripts. functions.sh.

, MLO SPL.