Buildroot for Raspberry Pi

This buildroot overlay will produce a bleeding-edge, light-weight and trimmed down toolchain, rootfs and kernel for the Raspberry Pi. It's intended for advanced users and specific embedded applications.

Before You Begin

• If you're not familiar with Buildroot and what it can and can't do, please take the time to read the manual.

• You must be pretty comfortable with cross-compilation in order to use rpi-buildroot.

Test Drive

You can test drive rpi-buildroot by following the instructions below:

wget http://dl.guillermoamaral.com/rpi/sdcard.img.xz
xz -d sdcard.img.xz
sudo dd if=sdcard.img of=/dev/sdx # replace *sdx* with your actual sdcard device node

There's now also a test drive image for the Raspberry Pi 2:

wget http://dl.guillermoamaral.com/rpi/sdcard2.img.xz
xz -d sdcard2.img.xz
sudo dd if=sdcard2.img of=/dev/sdx # replace *sdx* with your actual sdcard device node

The default user is root, no password is required.

Building

git clone --depth 1 git://github.com/gamaral/rpi-buildroot.git
cd rpi-buildroot
make raspberrypi_defconfig # if your target is a Raspberry Pi 2, use 'raspberrypi2_defconfig'
make nconfig         # if you want to add packages or fiddle around with it
make                 # build (NOTICE: Don't use the **-j** switch, it's set to auto-detect)

Deploying

Script

I've added a script that can automatically flash your sdcard, you simply need to point it to the correct device node, confirm and you're done!

Notice you will need to replace sdx in the following commands with the actual device node for your sdcard.

# run the following as root (sudo)
board/raspberrypi/mksdcard /dev/sdx

Manual

You will need to create two partitions in your sdcard, the first (boot) needs to be a small W95 FAT16 (LBA) patition (that's partition id e), about 32 MB will do.

Notice you will need to replace sdx in the following commands with the actual device node for your sdcard.

Create the partitions on the SD card. Run the following as root. Notice all data on the SD card will be lost.

fdisk /dev/sdx
> p             # prints partition table
> d             # repeat until all partitions are deleted
> n             # create a new partition
> p             # create primary
> 1             # make it the first partition
> <enter>       # use the default sector
> +32M          # create a boot partition with 32MB of space
> n             # create rootfs partition
> p
> 2
> <enter>
> <enter>       # fill the remaining disk, adjust size to fit your needs
> t             # change partition type
> 1             # select first partition
> e             # use type 'e' (FAT16)
> a             # make partition bootable
> 1             # select first partition
> p             # double check everything looks right
> w             # write partition table to disk.

Now format the boot partition as FAT 16

# run the following as root
mkfs.vfat -F16 -n BOOT /dev/sdx1
mkdir -p /media/boot
mount /dev/sdx1 /media/boot

You will need to copy all the files in output/images/boot to your boot partition.

# run the following as root
cp output/images/rpi-firmware/bootcode.bin /media/boot
cp output/images/rpi-firmware/fixup.dat /media/boot
cp output/images/rpi-firmware/start.elf /media/boot
cp output/images/zImage /media/boot/kernel.img
cp output/images/*.dtb /media/boot
umount /media/boot

The second (rootfs) can be as big as you want, but with a 200 MB minimum, and formated as ext4.

# run the following as root
mkfs.ext4 -L rootfs /dev/sdx2
mkdir -p /media/rootfs
mount /dev/sdx2 /media/rootfs

You will need to extract output/images/rootfs.tar onto the partition, as root.

# run the following as root
tar -xvpsf output/images/rootfs.tar -C /media/rootfs # replace with your mount directory
umount /media/rootfs