yocto-pi-zero

Yocto repository based on "Ready, Set, Yocto!" for Raspberry Pi Zero

Setup

Install nix

Run

git submodule update --init
nix-shell

Enter build environment

If you are starting from scratch, remove the directory builds/rpi0 (rm -r builds/rpi0)

Run the following to enter the build environment:

source <path/to/repo>/poky/oe-init-build-env <path/to/repo>/builds/rpi0

This will drop you into the rpi0 directory. You need to make some changes to the configuration if you haven't set it up yet.

Edit conf/local.conf with the following changes:

MACHINE ??= "qemux86" --[to]--> MACHINE ??= "raspberrypi0-wifi"
Enable the UART: ENABLE_UART = "1"
Enable U_Boot: RPI_USE_U_BOOT = "1"

Edit conf/bblayers.conf so that the BBLAYERS variable includes the following:

BBLAYERS ?= " \
  <path/to/repo>/poky/meta \
  <path/to/repo>/poky/meta-poky \
  <path/to/repo>/poky/meta-yocto-bsp \
  <path/to/repo>/meta-openembedded/meta-oe \
  <path/to/repo>/meta-openembedded/meta-python \
  <path/to/repo>/meta-openembedded/meta-networking \
  <path/to/repo>/meta-openembedded/meta-multimedia \
  <path/to/repo>/meta-openembedded/meta-filesystems \
  <path/to/repo>/meta-raspberrypi \
  "

Raspberry Pi Kernel

The raspberry pi kernel can be difficult to fetch from the url. It is recommended to have a local copy of the repo and modify the path in the recipie to point at the local version.

A file local-raspberry-pi-kernel.patch contains the modifications needed to point at the local repo. To apply the changes, do:

cd meta-raspberrypi
git apply ../local-raspberry-pi-kernel.patch

By default, the raspberry pi kernel is cloned as a submodule in downloads/rpi-linux-kernel. You will need to update the absolute paths in the files modified by the patch above to work on your local system.

Build minimal image

This will take a while:

bitbake core-image-minimal

The output images will be in builds/rpi0/tmp/deploy/images/

Copy core-image-minimal to an SD Card

with dd:

sudo dd if=./tmp/deploy/images/core-image-minimal-raspberrypi0.ext3 of=<path/to/sdcard> bs=4M && sync

or using bmaptool

sudo bmaptool copy tmp/deploy/images/core-image-minimal-raspberrypi0.wic.bz2 <path/to/sdcard>