Hi Brigitte,
The current version of the Arago Project is based on OpenEmbedded-Core and the Yocto Project.
There are some legacy products still being shipped that use Classic Arago.
Please refer the section Note from below wiki link.
http://arago-project.org/wiki/index.php/Main_Page
Please follow the below wiki link to build for OMAP-L1:
http://processors.wiki.ti.com/index.php/Arago_build_recipe_for_OMAPL1
Thanks.