Re: [RFA] Introduce solib_loaded observer

Daniel Jacobowitz
2005-01-09T23:06:41Z

On Sun, Jan 09, 2005 at 11:58:18PM +0100, Mark Kettenis wrote:
> Date: Sun, 9 Jan 2005 17:37:33 -0500
> From: Daniel Jacobowitz <drow@false.org>
>
> On Sun, Jan 09, 2005 at 02:05:15PM +0100, Mark Kettenis wrote:
> >
> > Calling the observer after loading the symbols isn't possible. You
> > can set "auto-solib-add" to 0, and then the symbols will never be
> > loaded at all. So you'll always have to force loading the symbols
> > from within your observer anyway (but you only have to do so for the
> > threads library). From a code perspective the point where the
> > notification is called is the most logical. And that way it's less
> > likely that we see "auto-solib-add" related bugs ;-).
>
> At the same time, I worry that it's going to be confusingly
> inconsistent - for instance, I would have expected turning off
> auto-solib-add to prevent loading symbols for libpthread! Or at least,
> loading of full symbols (all libthread_db on GNU/Linux really needs are
> a couple of minsyms).
>
> We should try to be as consistent as possible. The current situation
> is very inconsistent too: if you turn off auto-solib-add, you won't
> get thread debugging support. It's true that for debugging support

Note that there's no other way to deliberately turn off thread
debugging at present.

> you usually only need a few minimal symbols. I considered rolling my
> own BFD-based lookup function, but I suspect that would result in a
> serious performance hit because I'd lose the benefit of caching.

I doubt it would be that serious. It'd be a bit tricky, of course, so
adding extra code for it seems like a shame. Perhaps we could read in
just the minsyms...

> Because of the auto-solib-add issue I don't think it is, but given the
> right arguments I think you can make me think differently. What to
> the others think of this?

I wonder if we can envision any other potential consumers for this
hook? What would they want to do?

--
Daniel Jacobowitz