Re: origin of alloca(3) (was: Undocumented systems/standards PWB and 32V)

[Alejandro Colomar <alx@kernel.org>]

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Hi Branden,

On Thu, Jan 01, 2026 at 05:53:10PM -0600, G. Branden Robinson wrote:
> > It would be good to check in which one alloca(3) was present.
> 
> There's _an_ `alloca()` in PWB/Unix 1.0.
> 
> https://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/source/s4/util/alloca.s
> 
> It's not declared in any header file I can find, and as you can see it's
> written in PDP-11 assembly, but it's there, and appears to do what a
> modern C programmer would expect of it.[1]
> 
> It appeared to get stuck into a library called "libpw.a".
> 
> Static, of course, because there were no shared libraries back then.
> 
> https://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/source/s4/util/makefile
> 
> Close enough?  :)

Yup; I guess we could change PWB to PWB1 in the HISTORY of alloca(3).

Thanks!


Cheers,
Alex

> 
> Regards,
> Branden
> 
> [1] I see some other familiar stuff here...
> 
> https://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/source/s4/stdio



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