fwup meta layer

This is a Yocto meta layer for building fwup into Yocto projects.

Dependencies:

This layer depends on:

URI: https://github.com/openembedded/meta-openembedded.git layers: meta-oe branch: master

Usage

For conf/bblayers.conf you have to add

BBLAYERS ?= " \
   ...
  path_to_source/sources/meta-fwup \
  "

There are two main use cases:

One is to add IMAGE_INSTALL_append = "fwup" in conf/local.conf and run bitbake core-image-minimal to get an image with fwup support.

The second one is to add the following configuration in conf/local.conf:

# Add image_types_fwup to the system
IMAGE_CLASSES += "image_types_fwup"

# Declare that we want to make fwup images
IMAGE_FSTYPES = "fwup"

# It's mandatory to define a fwup config file format
FWUP_FILE = "sdimg-raspberrypi0-wifi.fwup"

When running bitbake core-image-minimal a .fw image will be created at tmp/deploy/image/<MACHINE NAME>/core-image-minimal-<MACHINE NAME>.rootfs.fw

Firmware authentication

fwup is able to create firmware authenticated archives. It's also possible to sign firmware archives generated by image_types_fwup image class. The following configuration can be added into local.conf configuration:

# Enable fwup sign
FWUP_SIGN_ENABLE = "1"

# Private key file location
FWUP_PRIVATE_KEY_FILE = "/data-work/yocto/work/fwup/build/fwup-key.priv"

# Public key file location
FWUP_PUBLIC_KEY_FILE = "/data-work/yocto/work/fwup/build/fwup-key.pub"

The variable FWUP_SIGN_ENABLE enables the code responsible for calling fwup command with the right parameters. Also the variables FWUP_PRIVATE_KEY_FILE and FWUP_PUBLIC_KEY_FILE have to point to the correct location of private and public key files.

One way to create a key pair is using the command fwup -g. However, others methods also exist.

Flashing images

In order to flash an image to a bootable device, it's possible to use either fwup or bmaptools.

Make sure you have write access to the bootable device before executing the below commands.

fwup

Update your local.conf file with:

IMAGE_FSTYPES += "fwup"

Get an image first:

bitbake fwup-native -caddto_recipe_sysroot

Call fwup-native:

oe-run-native fwup-native \
  fwup -a -d /dev/sdc -i myfirmware.fw -t complete \
  -i tmp/deploy/images/raspberrypi5/image.rootfs.fwup

bmaptools

Update your local.conf file with:

IMAGE_FSTYPES += "fwup fwup.bmap"

Get an image rebuild:

bitbake image

Add bmaptool-native to sysroot:

bitbake bmaptool-native -caddto_recipe_sysroot

Call bmaptool-native:

oe-run-native bmaptool-native bmaptool copy \
 tmp/deploy/images/raspberrypi5/image.rootfs.fwup \
 /dev/sdc

For more details, check the Yocto's documentation about Flashing Images Using bmaptool.