Re: MODULAR option and advertised semaphore support

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

On Fri, Nov 05, 2010 at 11:33:45PM +0100, Nicolas Joly wrote:
> On Fri, Nov 05, 2010 at 06:05:14PM +0100, Nicolas Joly wrote:
> > On Fri, Nov 05, 2010 at 05:02:09PM +0100, Matthias Drochner wrote:
> > > 
> > > If I understand it correctly, with Nicolas' proposal an innocent
> > > "sysctl -a" would load the semaphore module. I don't have a better
> > > idea yet, but this approach doesn't scale -- if done for more
> > > modules all of them would be loaded with this single "sysctl"
> > > invocation.
> [...]
> > I'm not a sysctl expert, but does making them hidden (CTLFLAG_HIDDEN)
> > should help ? The way i understand it, only explicit calls would
> > triggers module loading ...
> 
> I do checked this, and CTLFLAG_HIDDEN do indeed prevent `sysctl -a'
> from calling/reporting it. It's only triggered for explicit request
> `sysctl kern.posix_semaphore'.

Being in turn neither a module(9) nor a sysctl(9) expert, I would assume
that one fundamental principle of modules is that these should completely
clean-up after an unload, leaving no traces to the system. Should a query of
_SC_SEMAPHORES succeed even if the corresponding module does not exist?
It is also unclear to me how a module can load itself.

- Jukka.