[TUHS] History of symbol preemption

[Larry McVoy]

On Mon, Jan 13, 2020 at 01:45:48PM -0800, Rico Pajarola wrote:
> On Mon, Jan 13, 2020 at 1:44 PM Paul Winalski <paul.winalski at gmail.com>
> wrote:
> 
> > On 1/13/20, Rico Pajarola <rp at servium.ch> wrote:
> > >
> > > yes, but unless my memory is playing tricks, SunOS a.out had this
> > feature.
> >
> > Do you mean support for shared libraries, or symbol preemption?
> >
> symbol preemption

My memory of this is it was dns lookups that wanted something like this.
SunOS really wanted the world to love YP but the world wanted Sun to
support DNS.  You could, and people did, make a shared lib that overloaded
the default gethostbyname(3) that wanted to do YP, the lib would provide
a DNS based one instead.

That's where I first learned of this stuff.  Gingell would know if you
want to know for sure.