If at first you don't succeed, try try again: Flashing an old Beaglebone Black eMMC

 

2019 Hugo Award for Best Novelette: Zen Cho

Back in 2016 I bought a few Beaglebone Blacks, but did not get round to using them. I guess they were superseded by the later-model Raspberry Pi's. 

Beaglebone Black

The Pi has always been less reliable than the Beagleboard or Beaglebone. Broadcom USB subsystem was especially flaky and since the Pi USB bus handled both disk IO as well as Ethernet, you are often SOL as Broadcom is not really reknown for fixing things. Little things like industrial temperature rating of 85 degrees Celsius. And having to run Linux from sdcards, which are certain to wear out. Even worse the full-size sdcard sockets fail after a few years. Luckily the later Pi models use microsd sockets, but I am still stuck with a bunch of Pi Model Bs and their flaky sdcards.

The Pi had irresistible things going for it. It was way cheaper, had more addon modules (ie 'hats'), and best of all, it had Debian. There was no longer the month-long struggle to get Angstrom Linux to run properly. Yet those niggling problems ...

Getting my Beaglebone Black running was unexpectedly painless. I plugged it into my laptop USB port and it was running. It came up as /dev/ttyACM0 a serial port. No problem, all I needed was minicom, and the default settings of 115200 baud, 8 bits, 1 stop, no parity.

Default account is 'debian' and password 'tempwd'. There is no root password. I did not have to struggle with Angstrom. In fact I forgot to put in the sdcard. That meant it loaded from on-board mass storage. And it was Debian!

root@beaglebone:~# cat /etc/dogtag

BeagleBoard.org Debian Image 2015-03-01

Turned out the onboard memory was eMMC, still flash memory, but in IC form without those dreaded sockets. Memory is 512MB and there is no built-in WiFi; that would come only in the Beaglebone Black Wireless.

From bottom left: USB Master socket, microsd  and the elusive User-boot button

First order of business with Debian is to get it up to date. I connected it via copper LAN to my ADSL modem where it found the Internet on its own. But 'apt-get update' had errors, even though it technically did not fail:

root@beaglebone:~# apt-get update

W: Failed to fetch http://ftp.us.debian.org/debian/dists/wheezy/contrib/binary-a

rmhf/Packages  404  Not Found [IP: 64.50.233.100 80]

W: Failed to fetch http://ftp.us.debian.org/debian/dists/wheezy/non-free/binary-

armhf/Packages  404  Not Found [IP: 64.50.233.100 80]

W: Failed to fetch http://ftp.us.debian.org/debian/dists/wheezy-updates/main/bin

ary-armhf/Packages  404  Not Found [IP: 64.50.233.100 80]

'apt-get upgrade' finished OK:

root@beaglebone:/home/debian# apt-get upgrade

But the version was wheezy, and really old. Not to worry, I reached for the latest images, and downloaded AM3358 Debian 9.12 2020-04-06 4GB SD ImgTec. It only needed a tiny (4GB!) microsd card, and:

$xzcat bone-debian-10.3-iot-armhf-2020-04-06-4gb.img.xz | sudo dd of=/dev/sdc

7372800+0 records in

7372800+0 records out

3774873600 bytes (3.8 GB, 3.5 GiB) copied, 3001 s, 1.3 MB/s

But it did not boot from the microsd, and instead after an hour or so booted from eMMC. Time to Read the Manual. The manual is no fluffy faux-friendly 'Getting Started' guide; it reads like a datasheet with schematics in glorious abundance.

There is mention of a 'Boot button', where if held down and the beaglebone is power-cycled it will force a boot from sdcard. But it did not work - and eventually always reverted to the old eMMC wheezy Debian.

After wasting a couple of days ruling out a hardware malfunction, the problem had to be the Debian image. One hint was that Debian Image 2015-03-01 would not mount  Debian 2020-04-06. That would point to an ext3 filesystem incompatibility. The existing eMMC Debian code would be needed to mount and boot the new Debian before flashing can commence.

And yet all this  has been solved before; one compromise is to use an fossil filesystem (like FAT16) just for booting, and indeed Debian 015-03-01 had such a partition but not Debian 2020-04-06. Usually SoCs have separate bootrom to prevent bricking incidents like this (like its close cousin the Beaglebone White), but this is easy enough to test.

beaglebard.org maintains a complete archive of old images, and hoping for an intermediate Debian that will be compatible with both, I picked Debian 2016-12-09. Then it s a simple matter of:

$xzcat bone-debian-8.6-iot-armhf-2016-12-09-4gb.img.xz > /dev/sdc

And it booted from microsd, just like that.

root@beaglebone:~# cat /proc/version

Linux version 4.4.36-ti-r72 (root@a2-imx6q-wandboard-2gb) (gcc version 4.9.2 (Debian 4.9.2-10) ) #1 SMP Wed Dec 7 22:29:53 UTC 2016

You need to prepare the new image for flashing. Just find the file /boot/uEnv.txt and uncomment the last line:

cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh

To flash the eMMC, I added the 5V power cable, and powered off. Then with the microsd still in, held down 'User boot'  button and powered back on. This worked right off the bat; the blinkenlights did an impression of Pong, and when finished, all lit up, then shut down.

On powering up, and removing the microsd, I get:

root@beaglebone:~# cat /etc/dogtag

BeagleBoard.org Debian Image 2016-12-09

Our imugi is not yet a dragon, but this is clearly The Way. The trusty sdcard is then repurposed with:

$xzcat bone-debian-10.3-iot-armhf-2020-04-06-4gb.img.xz | sudo dd of=/dev/sdc

And now it booted off the microsd. Now all I need to do is to repeat the eMMC flashing process with the latest Debian Image, 2020-04-06. As a precaution I first upgraded without incident:

root@beaglebone:~# apt-get update

root@beaglebone:~# apt-get upgrade

Changed the default passwords did the usual sysadmin stuff. The eMMC flash went without incident, and unlike Zen Cho's Byam, my Beaglebone Black did not turn back but transformed its eMMC to Debian 2020-04-06.

Happy Trails.