[TUHS] Thoughts on Licenses

Bakul Shah bakul at iitbombay.org
Mon Jul 4 03:48:02 AEST 2022

On Jul 3, 2022, at 11:26 AM, Clem Cole <clemc at ccc.com> wrote:
> On Sun, Jul 3, 2022 at 11:30 AM Bakul Shah <bakul at iitbombay.org <mailto:bakul at iitbombay.org>> wrote:
> You may be thinking of MINIX 1. It was a from-scratch implementation that was syscall compatible with V7 but IIRC it didn't have any sort of memory protection as it was designed to run on 8088.
> Minux and specifically M1 was and always has been, a uK.  And yes, M1 does not need an MMU - since it was designed to run on an 8088.  IIRC this was Linus' original objection when he wanted to run on his 386-based PC (Wyse 32:16 box, IIRC). The key was Andy wanted to teach his students about V7 without running afoul of the AT&T license as Lions had with V6.

Er.. a "microkernel" without an MMU is basically nothing more than a thread switcher (not unlike a variety of "realtime" embedded kernels like threadX and what not). 

> What runs on the Intel Management Engine
> It's called the Intelligent Platform Management Interface <https://streaklinks.com/BHBsBCyMjMy7xGTaiw4nohuO/https%3A%2F%2Fwww.intel.com%2Fcontent%2Fwww%2Fus%2Fen%2Fproducts%2Fdocs%2Fservers%2Fipmi%2Fipmi-second-gen-interface-spec-v2-rev1-1.html> - a.k.a. IPMI

>  is MINIX 3, ... with NetBSD userland.
> Actually, if you want to pick nits, neither statement is correct (remember for whom I work). 

Not sure which statements you are talking about that are incorrect.

Minix3 running on ME was in the news a few years back. See for instance: https://itsfoss.com/fact-intel-minix-case/ -- Websearch reveals many articles on IME + MINIX, hardly any to IPMI + MINIX.

MINIX 3 + NetBSD userland is pretty much what minix3.org website says!

[And no, I was not aware of who you work for.]

In any case, sounds like you were talking about something not (well)known outside of Intel.

>  MINIX 1 and MINIX 3 are related 
> That's because M3 added the MMU support that M1 lacked.   But there is nothing in M3 that IPMI is using other than it is the current version from Andy's team.  What IPMI has as an underlying uK is heavily hacked and is a 'derivative work' - the local uk is basically providing V7 interfaces to some special programs. 

I think Tanenbaum's point was that MINIX3 is nothing like MINIX1 except in name.

> It made little sense to recreate something for the platform engine, and Minux was picked because it was smaller than any of the *BSDs and was not GPL'ed so Intel IP was still protected.  

No argument here :-)
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