[TUHS] First Unix-like OSes not derived from AT&T code?

Miod Vallat miod at online.fr
Tue May 3 17:40:11 AEST 2022


> > At the end of the AOS work circa 1996, most of the kernel was 4.4,
> > except for the network stack which was 4.3-Reno, and the VM system which
> > was still 4.3 (hence no mmap).
> 
> 
> This happened outside of IBM, didn't it? What prevented the rest of the VM
> code being ported?

Most - if not all - the AOS work was done by Roger Florkowski and Mark
Dapoz, and Roger was definitely working for IBM at that time.

I think time was limiting factor, but also Roger was not really wanting
to port the Mach VM to AOS due to the RT MMU limitations - in
particular, there is no way for multiple virtual addresses to point to
the same page, so you need to keep evicting/switching mappings when you
want a page to be available to the kernel and the currently running
userland process. That was fixed in the POWER MMU.

> I vaguely remember Metaware being somewhat religiously extreme, but again
> the details are fuzzy now. Was there some kind of ecclesiastical reference
> in the man page?

I'm afraid that doesn't ring any bell.

Miod


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