[TUHS] Early shared library implementations

[Charles H Sauer]

On 9/30/2021 5:39 AM, arnold at skeeve.com wrote:
> Paul Ruizendaal via TUHS <tuhs at minnie.tuhs.org> wrote:
> 
>> So far, I have not come across any shared library implementations or
>> precursors in early Unix prior to SunOS 4.
> 
> In more or less the same time frame, the AT&T UnixPC / 3B1, which was
> OEM'ed from Convergent, had shared libraries.  This was ~ 1986.
> 
> I don't know the details of how it worked and how one built the shared
> libraries; I am sure that it was an independent implementation from Sun's.
> 
> This was done on top of a System V Release 2 kernel.  Later versions
> of the OS had some bits of the SVR3 user land, but the kernel remained
> SVR2 based.
> 
> There is a 3B1 emulator and disk images for it available for anyone
> who really wants to go back to a system with short filenames and no
> job control. :-)

I'm very hazy on the details, because I wasn't directly involved, but we 
had shared libraries in AIX for the RT starting with the initial release 
in 1986 (based on SVR1). Larry Loucks did most of the design, with help 
from ISC folks and maybe Rick Simpson. Larry mentions this work in our 
AIX 2 paper 
(https://technologists.com/sauer/Advanced%20Interactive%20Executive%20(AIX)%20Operating%20System%20Overview.pdf) 
but I don't see any useful description, nor do I see anything useful 
skimming http://www.bitsavers.org/pdf/ibm/pc/rt/ docs. A more 
sophisticated shared library design was one of the additions in AIX 3.

Charlie

P.S. That paper and 
https://technologists.com/sauer/SA23-1057_IBM_RT_Personal_Computer_Technology_1986.pdf 
do include a bit more discussion of our memory mapped files since 
support for those was a primary goal of the 801 virtual memory design 
(summarized in the "Rosetta" paragraph of 
https://notes.technologists.com/notes/2017/03/08/lets-start-at-the-very-beginning-801-romp-rtpc-aix-versions/). 


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