[TUHS] RFS (was Re: Re: forgotten versions)

Paul Ruizendaal via TUHS tuhs at tuhs.org
Mon Jun 20 22:28:06 AEST 2022

> I don't know the exact history of RFS a la System V, but I
> don't think it was Peter Weinberger's stuff, and it certainly
> wasn't his code.

Peter’s code is available in the V8 and V9 trees on TUHS.

The Sys V repositories on Github appear to include RFS code in all of R3.0, R3.1 and R3.2.

At first glance, it seems quite different from the V8/V9 code.

> Peter, being a self-described fan of cheap hacks, also wasn't
> inclined to spend much time thinking about general abstractions;
> in effect he just turned various existing kernel subroutines
> (when applied to a network file system) into RPCs.  The
> structure of the file system switch was rather UNIX-specific,
> reflecting that.

Yes, well put. I’ve back ported his filesystem switch to V6/V7 and it is very light touch: on the PDP11 it added only some 500 bytes of kernel code (after some refactoring).

With hindsight it seems such a logical idea, certainly in a context where the labs were experimenting with remote system calls in the mid 70’s (Heinz Lycklama's work on satellite Unix) and early 80’s (Gottfried Luderer et al. on distributed Unix — another forgotten version). It is such a powerful abstraction, but apparently very elusive to invent.


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