4.2::SYSV compatability problem

[Guy Harris]

> > (Discussion of the fact that some System V versions enforce the
> > "only one definition of an extern" rule)

> I have great sympathy for you, having once lived in a motel
> room in Red Bank, New Jersey while fixing a very large (> 100,000
> lines) C program written in BSD C so that SYS V C could load it.
> 
> Besides, even on BSD, its nice to know where your
> variables are really allocated, in case you ever want to tune your
> programs to reduce paging, etc.

****it, the world is *NOT* divided into BSD and System V - it's not
even divided into BSD and USG!  System V is the *only* UNIX system that
enforced that rule.  V6, PWB/UNIX 1.0, V7, and System III worked the same
way as 4.xBSD did - in fact, 4.xBSD behaved that way because 32V behaved
that way, and 32V behaved that way because V7 behaved that way, and...

So next time you run into an incompatibility between one version of UNIX
and another, don't jump to conclusions as to whose fault it is... System V
Release 2 backed the change out, probably because so many people lived
in motel rooms in Red Bank (count your blessings, it wasn't Secaucus).
Lay the blame/credit for that one squarely at the feet of the USDL.

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy