An interesting point of view is given in https://www.youtube.com/watch?v=-zRN7XLCRhc https://www.youtube.com/watch?v=-zRN7XLCRhc (Fork Yeah! The Rise and Develo

An interesting point of view is given in https://www.youtube.com/watch?v=-zRN7XLCRhc https://www.youtube.com/watch?v=-zRN7XLCRhc (Fork Yeah! The Rise and Development of illumos). There are some sections that briefly touch on how Solaris was open-sourced, and how incredibly difficult and time intensive it was to do because of how much code there was that belonged to other people/companies that had to be rewritten or just excised if possible. And despite all the effort they put in, it still didn't work out 100% of the way they wanted it to (thus the existence of illumos).