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

Wed Apr 22 04:08:39 AEST 2026

On 4/21/2026 12:29 PM, Adam Koszek wrote:
> The Wikipedia says that Jolix could be another. Looks like they had the 
> copyright on it?
> 
> I’d be very interested in hearing more about commercial efforts - AIX, 
> IRIX, Solaris.

I'm not sure what you're asking about AIX. If you haven't read what I 
wrote at 
https://notes.technologists.com/notes/2017/03/08/lets-start-at-the-very-beginning-801-romp-rtpc-aix-versions/, 
see that. In brief, AIX 1 & 2 on the RT/PC used SVR1 "on top of" the VRM 
to provide paging and other augmentations. AIX 3 for RS/6000 (& RT) 
eliminated the "Virtual Machine Interface" boundary between the USG code 
and the IBM code. Charlie

> The part that always felt interesting was what cool things happened 
> behind the corporate door - which UNIX got to run on 2 CPUs first, and 
> then how it all got scaled up, who got SMP networking first.
> 
> I also remember from MeetBSD that folks had good words about Solaris 
> efforts to refactor things around VFS, buffer cache. Perhaps many more 
> ideas.
> 
> Adam
> 
>> On Apr 18, 2026, at 10:16 PM, Bakul Shah via TUHS <tuhs at tuhs.org> wrote:
>>
>>
>>
>>> On Apr 18, 2026, at 8:49 PM, Charles H. Sauer 
>>> <sauer at technologists.com> wrote:
>>>
>>>
>>>> On Apr 18, 2026, at 9:52 PM, Bakul Shah via TUHS <tuhs at tuhs.org> wrote:
>>>>
>>>> I believe Sol later merged into Chorus was a reimplementation in 
>>>> Pascal. I think this was a microkernel based system...
>>>> I believe Locus distributed OS designed at UCLA was also Unix 
>>>> compatible. I guess you can add Xinu as well as Amoeba to the list.
>>>
>>> I intentionally never looked at Locus source, but had much 
>>> interaction with Gerry Popek and Bruce Walker while I was at IBM and 
>>> they were working with IBM. I have a memory of Bruce telling me they 
>>> started with 4.1BSD, but I question that memory. Just glancing at 
>>> their book (https://www.penguinrandomhouse.com/books/655167/the- 
>>> locus-distributed-system-architecture-by-gerald-j-popek/), the only 
>>> cited Unix reference I see is the 1978 Ritchie/Thompson BSTJ paper. 
>>> Section 1.5 Unix Compatibility of their book says “For virtually all 
>>> applications code, the LOCUS system can provide complete 
>>> compatibility, at the object code level, with both Berkeley Unix and 
>>> System V, …” I suspect that the first Locus prototypes were based on 
>>> BSD earlier than 4.1.
>>
>> Thanks. I have the Locus book but couldn't find it. If they started 
>> with BSD code, they must've had to do major surgery to achieve a 
>> distributed system! Except for bootstrapping & drivers probably easier 
>> to start from scratch....
>>
>> I guess KeyNIX (atop KeyKOS) should be added as well:http://cap- 
>> lore.com/CapTheory/KK/UnixOnMicroKernel/ <http://cap-lore.com/ 
>> CapTheory/KK/UnixOnMicroKernel/>
> 

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