Archive for the ‘embedded’ Category

My BeagleBone Black came pre-installed with a 2-year-old Debian Wheezy on it’s eMMC chip (image, hashes). The out-of-the-box experience is actually quite impressive: the BeagleBone presents itself over the USB bus as a mass storage device with the needed drivers and some documentation. Once you install the driver (only the RNDIS is needed, the Black does not have a serial-over-USB anymore), you can just surf to the BeagleBone and control USER-LEDs from your web browser. Impressive!

But I don’t want nor need these fancy features eating up CPU, diskspace and RAM, so I went looking for a minimal Debian image to use. Besides the bare minimum, I wanted the Ethernet-over-USB to work, and SSH.

  1. Get a copy of the BeagleBoard image builder
  2. Build a rootfs tarball for the desired config. I used, which matched my requirements quite nicely. You can see the (additional) packages that will be installed listed in the corresponding config file.
    ./ -c
  3. From the generated directory inside deploy, run
    ./ --img-1gb ~/disk-image.img --dtb beaglebone

    I wanted to keep the FAT boot partition, which is no longer needed, so I reverted that part of the commit before running the above command.

  4. dd the generated image (hash) onto an SD card.

To boot from the SD card, press the boot button (S2) at power-on and release when the 4 User-LEDs are on. Be patient: it took my board ~90 seconds to get SSHd up and running.

Note: sometimes, udhcpd would refuse to start. Rebooting (i.e. press the power button (S3) briefly, wait for the LEDs to go off, press-and-hold S2, press S3, release S2 when 4 LEDs are on) helped. I’m guessing it’s a race condition on bootup that sometimes prevent udhcpd from starting. Manually assigning your side also works.

You can use the /opt/scripts/tools/ script to grow the root partition to the actual size of the SD card instead of the 1GB it originally has.