yocto-public/2-usage/layercreate.md

Creating a Layer

The layer is nothing more than a folder with a single configuration file to indicate its name and where to find its resources.

The layer can be put anywhere on the system.

Manual creation

There are other ways to create layers that are specific to certain usages (BSP, Distribution, ...), but this is the manual way to create a minimal layer.

#The path to your layer
LAYER=$POKY/build/meta-mylayer

mkdir $LAYER
cd $LAYER

Write $LAYER/conf/layer.conf (replace mylayer by your layer name):

BBPATH .= ":${LAYERDIR}"

# Register the layer recipes into the variable BBFILES
BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
            ${LAYERDIR}/recipes-*/*/*.bbappend"

BBFILE_COLLECTIONS += "mylayer"
BBFILE_PATTERN_mylayer = "^${LAYERDIR}/"
BBFILE_PRIORITY_mylayer = "5"

Once created, you will need to add the layer path in the `BBLAYER` variable, usually defined in `$POKY/build/conf/local.conf`

Layer organization

Path	Role
conf/layer.conf	Layer configuration
conf/machine/*.conf	Machines
conf/distro/*.conf	Distributions
classes/	Classes
recipes-*/	Recipes
README	Readme file (optional)

Layer management tools

bitbake-layers <command> [arguments]
# Available commands:
#   help
#     display general help or help on a specified command
#   show-recipes
#     list available recipes, showing the layer they are provided by
#   show-cross-depends
#     figure out the dependency between recipes that crosses a layer boundary.
#   show-appends
#     list bbappend files and recipe files they apply to
#   flatten
#     flattens layer configuration into a separate output directory.
#   show-layers
#     show current configured layers
#   show-overlayed
#     list overlayed recipes (where the same recipe exists in another layer)