Raspberry Pi

Intro
=====

These instructions apply to all models of the Raspberry Pi:
- the original models A and B,
- the "enhanced" models A+ and B+,
- the model B2 (aka Raspberry Pi 2)
- the model B3 (aka Raspberry Pi 3).

How to build it
===============

Configure Buildroot
-------------------

There are two RaspberryPi defconfig files in Buildroot, one for each
major variant, which you should base your work on:

For models A, B, A+ or B+:

$ make raspberrypi_defconfig

For model 2 B:

$ make raspberrypi2_defconfig

For model 3 B:

$ make raspberrypi3_defconfig

Build the rootfs
----------------

Note: you will need to have access to the network, since Buildroot will
download the packages' sources.

You may now build your rootfs with:

$ make

(This may take a while, consider getting yourself a coffee ;-) )

Result of the build
-------------------

After building, you should obtain this tree:

output/images/
+-- bcm2708-rpi-b.dtb [1]
+-- bcm2708-rpi-b-plus.dtb [1]
+-- bcm2709-rpi-2-b.dtb [1]
+-- bcm2710-rpi-3-b.dtb [1]
+-- boot.vfat
+-- kernel-marked/zImage [2]
+-- rootfs.ext4
+-- rpi-firmware/
| +-- bootcode.bin
| +-- cmdline.txt
| +-- config.txt
| +-- fixup.dat
| `-- start.elf
+-- sdcard.img
`-- zImage

[1] Not all of them will be present, depending on the RaspberryPi
model you are using.

[2] This is the mkknlimg DT-marked kernel.

How to write the SD card
========================

Once the build process is finished you will have an image called "sdcard.img"
in the output/images/ directory.

Copy the bootable "sdcard.img" onto an SD card with "dd":

$ sudo dd if=output/images/sdcard.img of=/dev/sdX

Insert the SDcard into your Raspberry Pi, and power it up. Your new system
should come up now and start two consoles: one on the serial port on
the P1 header, one on the HDMI output where you can login using a USB
keyboard.