and you can download and run it: https://barrelfish.org/download.html
sadly, last release 2020-03-23:
The Barrelfish project is no longer active. See https://systems.ethz.ch/ for information about our current research activities.
It is still interesting though.
Ten years of OS research, supporting x86, ARMv7 and ARMv8 devices, leading to 2021 talk about hardware and subsequent design of new hardware (RISC-V).