[TUHS] shared memory on Unix

Clem Cole clemc at ccc.com
Thu Feb 2 03:18:47 AEST 2017


‚ÄčI do not remember the BBN share memory code, but the Columbus shared
memory and semaphore changes were certainly known in 1978 and 1979.   I
remember seeing a man page for them from one of the OYOC types - Phil Karn
maybe, but its possible it was tjk.   As quick scan of my paper archives,
did not turn anything up; and I do not remember any system at CMU that had
the code, only looking at a hard copy of the man pages.

My memory is that the API changed a little by the time they became the
System V API; as I remember thinking that the IPC was "new" when I first
saw it in a system that had all three.

On Wed, Feb 1, 2017 at 11:21 AM, Mary Ann Horton <mah at mhorton.net> wrote:

> I*'m not sure what you mean by CB3, but these features (shared memory,
> semaphores, IPC) were added to CB-UNIX (Bell Labs, Columbus) precisely
> because they were needed in real time telco systems and not preset in the
> versions from New Jersey.  This would have been in the early 1980s.  When I
> got there in 1981 I think CB-UNIX was already well established and had
> these features.  (These would show up, ironically, in /usr/ucb, which did
> not stand for Berkeley.)
>
>     Mary Ann
>
>
>
> On 02/01/2017 06:18 AM, Paul Ruizendaal wrote:
>
>> The presence of some sort of shared memory facility in the
>> BBN V6 Unix kernel got me thinking about the origins of
>> shared memory on Unix.
>>
>> I had a vague recollection that primordial versions were present
>> in either PWB or CB3, but a quick glance at the source indicates
>> that this is not correct.
>>
>> What are the origins of shared memory on Unix, i.e. what came
>> before mmap() and SysV IPC? Was the BBN kernel the first to
>> implement such a facility on Unix?
>>
>> Paul
>>
>>
>
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