The guys from the (presumably dead) TUNES project seem to have liked writing essays more than actually writing code. (At least I was not able to find any). Compared to their cloud-castle project, Sysel seems boring and pure mainstream ^_^.
They seem to have a clear opinion on microkernel OS design (calling it an abstraction inversion) which I recommend reading.
While cannot agree with everything therein, the article (or manifesto or whatever it is) accurately points out the principal weaknesses of microkernel design as such (as well as the faults in existing microkernel-based designs).
HelenOS (Kids) Camp 2018 Report
2 months ago