L4Re

L4Re is an operating system framework that allows you to build custom operating systems. It also includes a hypervisor and virtual machine monitor.

The L4Re Operating System Framework provides the building blocks for creating custom operating systems with real-time, security, safety and virtualization features. Common deployments are the L4Re Hypervisor and L4Re Micro Hypervisor that form the base for a feature-rich virtualization platform for hosting workloads of general-purpose, real-time, security and safety kinds.

Website

You can find it more information on the official L4Re Website.