There are hundreds of meta layers from the Yocto Project, OpenEmbedded, communities, and companies that should be manually cloned inside the project source directory to be used. We can find them at http://git.yoctoproject.org/ or http://layers.openembedded.org.

In order to include, for example, meta-realtime in our project, we can change the content of configuration for Layers; click on Add layer, browse to the meta-realtime folder, and click on OK if we use Hob, as shown in the following screenshot:

We notice that the layers meta, meta-yocto, and meta-hob cannot be removed as they provide the core infrastructure and BSP for Hob. These layers are the Yocto Project definition, plus the Hob provider layer.

If we use the BitBake command lines, we can add a new layer by changing the file conf/bblayer.conf and add the absolute path to the new meta layer directory, as shown in the following source code. The line highlighted is the one to be added. The others are the default values...