7.5 External Layers
For the examples in the preceding sections, we used software packages and package groups from the OE Core layer meta and the Yocto Project base layer meta-yocto.
With steadily increasing support and contributions to the Yocto Project and OpenEmbedded, a growing number of additional layers with hundreds of recipes for myriad software packages are now available. Many of them are cataloged on the OpenEmbedded website. If you are looking for a recipe to build a specific software package, chances are that someone has already done the work.
The OpenEmbedded website’s metadata index1 lets you search by layer, recipe, and machine. For example, searching for Java by layer gives you a list of the layers that provide Java. Searching for JDK by recipes gives you a list of all recipes that build JDK packages together with the layer that provides the recipe.
The metadata index also lets you filter for the supported Yocto Project release to see if a recipe or layer is compatible with that particular release. Once you find the layer containing the software package recipe you are looking for, all you need to do is download the layer, include its path into the BBLAYERS variable of the conf/bblayers.conf of your build environment, and add the desired software package to your image using one of the methods described earlier.