Since the first Microkernel OS Devroom at FOSDEM 2012 and culminating today, there have been exactly 15 devrooms in 15 years dedicated to microkernel-based operating systems at each FOSDEM. As surprising or shocking this may sound to somebody who has been there all along, this time period already constitutes a small piece of history. While the computing world of today is not dramatically different or unrecognizable compared to 2012, maybe except for a few "minor" technologies such as HTML5 and LLMs ;), there have definitively been some changes and shifts of priorities.

Let us take this opportunity for a small retrospective of the last 15 years in the context of open-source microkernel-based operating systems. What problems have we been facing back then and how do they relate to the problems we face today? What have been the ups and downs? What are the important lessons learned?