New nvidia drivers available
dfr at nlsystems.com
Sun Aug 15 08:26:55 PDT 2004
On Sunday 15 August 2004 16:16, Justin T. Gibbs wrote:
> >> I thought that static constructor invocation was deterministic
> >> based on link order. Does the C++ spec really indicate that the
> >> order of construction can be random?
> > I don't think the spec places any restrictions on constructor
> > ordering. The problem here is that you get different behaviour
> > depending on whether you link with libGL first followed by
> > libpthread (in that case libpthread initialises first) or if you
> > link in the other order (in which case libGL initialises first). As
> > far as I can see, rtld calls the _init sections of each shared
> > library in reverse order with the last library linked against being
> > initialised first.
> But such ordering restrictions also apply to things like weak
> symbols, so I don't think that imposing a link order restriction to
> solve this issue is really a problem.
The algorithm for weak symbols is pretty simple - you always get either
the first strong symbol that rtld finds in its search or the last weak
symbol. I think we arrange for stuff like open(2) to be weak in libc
and strong in libpthread.
> >From my Microsoft days, I know that at least PowerPoint took
> > advantage
> of the known order of static constructor invocation. The splash
> screen was executed from a static constructor in the first .o linked
> into the executable. I'm just curious if this is something the C++
> spec says anything about. I'd be surprised if it didn't.
I'm sure that constructor ordering differs between binutils toolchains
on unix systems and Microsoft toolchains on win32 systems. The software
I write in my day job uses C++ constructors heavily and I'm certain
that things get constructed in a different order on the two platforms.
We just accept it and write code that can initialise in any order.
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