[TUHS] Is there a good, even definitive, list of reimplementations of the Unix kernel? What would good cut-off criteria be?

[Cameron Míċeál Tyre via TUHS]

Larry, thank you for that insight. It gives me a peace of mind. In my main job, the workday oftentimes starts with watching QNX Neutrino 6.3 boot up and later in each shift, my life literally depends on it. There is quadruple redundancy but it's still nice to get the insight from back when.

Cameron


-------- Original Message --------
On Sunday, 04/19/26 at 21:17 Larry McVoy via TUHS <tuhs at tuhs.org> wrote:

It was successful because only 3 people were allowed to commit code to the
microkernel itself.  They benchmarked every commit, down to counting cache
misses for important stuff like context switching and flagging commits
that increased cache misses.  That's what Dan Hildebrandt, one of 3 people
in question, told me.

I miss Dan, we were friends coming at the OS problem from different points
of view but we always managed to have great conversations.  He could point
out the benefits of a microkernel but acknowledge the costs.  It was never
personal with him, he was trying to strike a balance and I think QNX showed
that they did.

I have never seen that sort of discipline in any other OS team, including
the ones I worked on.

And I ran multiple people editing and compiling files on the pre-POSIX
QNX on a 286.  Pretty amazing.
--
---
Larry McVoy           Retired to fishing          http://www.mcvoy.com/lm/boat