LionsOS: an adaptable OS based on the seL4 microkernel

LionsOS is an operating system based on the seL4 microkernel with the goal of making the achievements of seL4 accessible. That is, to provide performance, security, and reliability.

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It is not a conventional operating system, but contains composable components for creating custom operating systems that are specific to a particular task. Components are joined together using the Microkit tool.
↫ LionsOS website

The project is under active research and development, led by the Trustworthy Systems research group at UNSW Sydney in Australia. The source code is available on GitHub.