Here are a few possibilities I've come across: * OsmocomBB (http://bb.osmocom.org/trac/ http://bb.osmocom.org/trac/) * An old HN discussion: https://news.ycom

Here are a few possibilities I've come across: * OsmocomBB (http://bb.osmocom.org/trac/ http://bb.osmocom.org/trac/) * An old HN discussion: https://news.ycombinator.com/item?id=7064187 https://news.ycombinator.com/item?id=7064187 * OKL4, a hypervisor, is used widely in basebands. AFAICT It was developed by Open Kernel Labs and was open. It seems to have been acquired by General Dynamics and I don't know it's current status (does anyone know more about it?) (https://gdmissionsystems.com/cyber/products/trusted-computing-cross-domain/microvisor-products/ https://gdmissionsystems.com/cyber/products/trusted-computin...)