Thread:Talk:BeagleBone Black Extracting eMMC contents/Thanks, Issues, and Suggestions

First off, thank you; this is a perfect way to handle reading/writing images.

However, it seems that the current boot image does not support writing files to FAT32 greater than 2GB, which makes it where a full image cannot be captured. I tried multiple SD cards formatted various ways, all of which only returned an image file of 2GB. By capturing the dd output to a log file I noticed:

dd: writing '/mnt/BeagleBoneBlack-eMMC-image-9466.img': File too large 206+0 records in 204+1 records out

At first I thought it was an issue with how the SD card was formatted, however by just booting the BBB to Debian and running a dd I was able to copy 4GB to the same SD card:

dd if=/dev/zero of=/mnt/zero.img bs=10M 410+0 records in 409+0 records out 4294967295 bytes (4.3 GB) copied, 421.259 s, 10.2 MB/s

So it would seem there is a big flaw in the current build. Perhaps it is related to this issue: https://groups.google.com/forum/#!topic/android-porting/alF-avcQNfI, which mentions some older linux kernels had the same issue?

I also suggest:

* Changing the dd line in the save autorun.sh to "dd if=/dev/mmcblk1 of=/mnt/BeagleBoneBlack-eMMC-image-$RANDOM.img bs=10M &> /mnt/autorun.log", or maybe even checking the length of the dd to ensure a full write. * Providing a warning that you should check that your img file is 4GB. * Note that the SD partition has to be "active" (as SaintGimp already mentioned, I just had the same issue initially). * Note that (on at least some revisions) the beaglebone must be powered by the barrel jack for it to work (I'm on a rev c board). * Note that you must let go of the S2 button after a couple seconds.