I recently began learning Yocto/Poky and built Beaglebone Black artifacts 
using the pyro branch. I configured things such that uEnv.txt, u-boot.img, 
MLO, and zImage are on a bootable FAT32 partition. eMMC was erased. It 
boots fine.

I also did some reading of the AM335x reference manual where I learned that 
the primary program loader (PPL in ROM) can identify FAT12/16/32 partitions 
and load MLO from there but a raw mode also exists where no filesystem is 
needed at all for MLO and U-Boot.

I found this write-up 
<http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0> regarding a 
BBB partition scheme 2.0. It looks to me as if the PPL for OMAP3 on 
supported the FAT technique and that OMAP4 because supporting the raw mode.

Regarding uEnv.txt: I am seeing these files in several places:

Are these cumulative in the sense that each one found overrides / adds 
information or does it stop with the first hit?

Is this searching a generic thing in U-Boot or specific to Beaglebone?

If there are differences in searching for this file what is the history of 
U-Boot for Beaglebone? Does the Yocto version use code that evolved from 
AM335x support from TI? Or was that adopted from this community when Yocto 
began using the hardware as a reference?

Is there a document that explains the use of the various uEnv.txt as used 
by the partition scheme 2.0?

Regarding FAT v. raw mode: Since the PPL for the AM335 supports both why 
change to the 2.0 strategy? What is the advantage?

Thanks.

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