On Sun, Jul 3, 2022 at 9:27 AM Clem Cole <clemc@ccc.com> wrote:

>
>
> On Sun, Jul 3, 2022 at 11:30 AM Bakul Shah <bakul@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.
>
> 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
>

IPMI is an entirely different subsystem from the ME.

ME runs on one of at least two superfluous x86 cores within the CPU die of
intel CPUs for a while that can run Intel and vendor supervisors.  When
this blew up in Intel’s face several years ago Minix 3 was the latest
incarnation.
https://github.com/hardenedlinux/firmware-anatomy/blob/master/hack_ME/me_info.md

IPMI is a sideband and could be anything including embedded Linux on a
dedicated ARM SoC which is common in large scale installations.

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

Maybe you are talking about something else.  Minix 3 (Andy’s last OS) does
indeed match this description, uK with NetBSD user.

 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.
>
> 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.
> ᐧ
> ᐧ
>