BBBlfs

Beagle Bone Black Linux Flash System

This project provides a way to flash a BeagleBone Black via USB from a Linux machine. The project was developed during Google Summer of Code '13.

Build

sudo apt-get install libusb-1.0-0-dev automake
./autogen.sh
./configure
make

Usage

Press the S2 button on the BeagleBone Black and apply power to the board. The board should start now into USB boot mode.

Connect the board to the host PC. The kernel should now identify your board as an RNDIS interface. Be sure you do not have any BOOTP servers on your network.

Go to bin/ and execute flash_script.sh It needs the flashing image as argument to be provided.

For now only .xz compressed images are supported.

sudo ./flash_script.sh [ debian | ubuntu | image.xz ]

debian and ubuntu will use tarball from armhf.com website

If there are bugs please feel free to contact me.

How to build the binary blobs

The full system works as follow:

The AM335x ROM when in USB boot mode exposes a RNDIS interface to the PC and waits to TFTP a binary blob that it executes. That binary blob is the SPL
Once the SPL runs it applies the same proceure as the ROM and TFTPs U-Boot
Again U-Boot applies the same thinking and TFTPs a FIT(flatten image tree) which includes a Kernel, Ramdisk and the DTB
U-Boot runs this FIT and boots the Kernel
When the kernel starts the init script exports the eMMC using the g_mass_storage kernel module as an USB stick to the Linux so it can be flashed

Building U-Boot for USB booting

Grab the latest U-Boot sources from git://git.denx.de/u-boot.git
Checkout commit id 524123a70761110c5cf3ccc5f52f6d4da071b959
Install your favourite cross-compiler, I am using arm-linux-gnueabihf-
Apply this patch to U-Boot sources https://raw.githubusercontent.com/ungureanuvladvictor/BBBlfs/master/tools/USB_FLash.patch

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- am335x_evm_usbspl_config
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi-

Now you have u-boot.img which is the uboot binary and spl/u-boot-spl.bin which is the spl binary

Building the Kernel

Grab the latest from https://github.com/beagleboard/kernel

git checkout 3.14
./patch.sh
cp configs/beaglebone kernel/arch/arm/configs/beaglebone_defconfig
wget http://arago-project.org/git/projects/?p=am33x-cm3.git\;a=blob_plain\;f=bin/am335x-pm-firmware.bin\;hb=HEAD -O kernel/firmware/am335x-pm-firmware.bin
cd kernel
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- beaglebone_defconfig -j4
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage dtbs modules -j4

After compilation you have in arch/arm/boot/ the zImage

Building the ramdisk

Our initramfs will be built around BusyBox. First we create the basic folder structure.

mkdir initramfs
mkdir -p initramfs/{bin,sbin,etc,proc,sys}
cd initramfs
wget -O init https://raw.githubusercontent.com/ungureanuvladvictor/BBBlfs/master/tools/init
chmod +x init

Now we need to cross-compile BusyBox for our ARM architecture

git clone git://git.busybox.net/busybox
cd busybox
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- menuconfig

Now here we need to compile busybox as a static binary: Busybox Settings --> Build Options --> Build Busybox as a static binary (no shared libs) - Enable this option by pressing "Y"

make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -j4
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- install CONFIG_PREFIX=/path/to/initramfs

Now we need to install the kernel modules in our initramfs

cd /path/to/kernel/sources
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- modules_install INSTALL_MOD_PATH=/path/to/initramfs

Packing things up

Now we need to put our initramfs in a .gz archive that the kernel knows how to process

mkdir maker
cd /path/to/initramfs
find . | cpio -H newc -o > ../initramfs.cpio
cd .. && cat initramfs.cpio | gzip > initramfs.gz
mv initramfs.gz /path/to/maker/folder/ramdisk.cpio.gz

Now we need to pack all things in a FIT image. In order to do so we need some additional packages installed, namely the mkimage and dtc compiler.

sudo apt-get update
sudo apt-get install u-boot-tools device-tree-compiler
cd /path/to/maker/folder
wget -O maker.its https://raw.githubusercontent.com/ungureanuvladvictor/BBBlfs/master/tools/maker.its
cp /path/to/kernel/arch/arm/boot/zImage .
cp /path/to/kernel/arch/arm/boot/dts/am335x-boneblack.dtb .
mkimage -f maker.its FIT

At this point we have all things put into place. You need to copy the binary blobs in the bin/ folder and run flash_script.sh

#Contact vvu@vdev.ro

vvu on #beagle, #beagle-gsoc

rubienr/BBBlfs