Which makes me wonder how does one read up on kernel internals outside of just perusing all the code, how do you get all the wonderful history that is just lost

Which makes me wonder how does one read up on kernel internals outside of just perusing all the code, how do you get all the wonderful history that is just lost unless you talk to someone who worked on it or find an insightful comment on HN. The one thing version control should emphasize more of is a way to go back through commits and let people (probably approved people) comb through and comment the code in a metadata way that the version control software can display without affecting commits. Would be neat to peruse code, hover (if you have a good editor / IDE ;) and see commentary by others on said code.