(Faulty) fstab entry makes BBB fall silent

New to BBB/Angstrom, but not to Linux, in my last step before catastrophy I added an fstab entry to the eMMC root file system which made the gadget inoperable - partially, at least.
What I did is

  1. partitioned and formatted an SD as Linux/ext3, with one single partition, and a name like ‘BBone’

  2. added a proper uEnv.txt to the SD root

  3. attached it and booted. Everything okay so far. Transferred some code to the SD, compiled it and ran the stuff - worked.

  4. added a mount entry to the fstab, looking like ‘LABEL=BBone /opt ext3 <defaults, maybe> 0 2’. (Sorry I don’t remember the exact entry contents)

  5. rebooted, and cried loud: the bone OS didn’t start up its USB-IP stack, so I couldn’t access it via TCP/IP any more, neither it did some DHCP request on the ethernet interface. It just does its well-known heartbeat pattern with the USRx-LED, so it is running in a certain way.
    It’s off-line. My question, now, is how to get it connected again on the shortest way. For me there are a few possibilities:

  6. Buy and attach UI-devices (screen, keyboard, etc) and do the fix via :0

  7. Install an OS to the SD, boot from there and fix the eMMC fstab

  8. Connect to the serial debug line - dunno what expects me there, but:complicated, as there are 3.3V levels AFAIK

Any recommendation and/or information very appreciated


If you didn’t change anything on the onboard flash you should be able to pull the SD card
and boot to the onboard flash. Then you can insert the flash and mount it and work on
the fstab file. The flash card is /dev/mmcblk0p1.

But your partitioning of the SD card doesn’t sound right to me. I’m using this procedure
for my SD card:


No, Rusty,

that would have been simple. But - as I said - I modified the fstab in the eMMC root file system, which is the onboard one.
And, the SD card is partitioned - and formatted - quite well: I remotely copied source to it, compiled & linked it, ran it. Wrote a few Megs of text files onto it, everything very okay.

The point is: my fstab entry accords to man mount' and man fstab’, which I consulted on a common Linux/GNU PC. On the BBB, the installed GNU systems seems to fall over this entry, it - maybe - doesn’t understand the ‘Label’ directive - dunno.
I suspect, there’s that busybox cripple in the game - could someone please do a

ls -l which mount
on the Bone and post the output here ? If this results in something like ‘/bin/busybox’ the next bug report is on its way …


Oops, sorry I missed the part about doing the fstab mangling on the eMMC.

Sounds to me like the easiest is your option 2; boot to a bootable SD card.

I wasn’t using the word mangling in a pejorative way, but rather as a fellow mangler; I’ve done
more than my share of mangling system configuration files.

Oh, Rusty,
I didn’t see it this way: I’m native German speaker, and may be that’s the reason I’ve a calm interpretation of the word ‘mangling’.

But, I appreciate your mindfullness, Thanks!

Great, thanks. I used to get in trouble with my co-workers because I’d make flippant remarks
which sometimes were interpreted differently than I had intended.