Re: Modularizing net80211 (was: link_set info needed)

[David Laight <david%l8s.co.uk@localhost>]

On Sat, Apr 28, 2012 at 10:13:11AM -0700, Paul Goyette wrote:
> On Sat, 28 Apr 2012, Joerg Sonnenberger wrote:
> 
> >On Sat, Apr 28, 2012 at 05:09:16PM +0100, David Laight wrote:
> >>>
> >>>This mechanism only works for modules that are "separate" from the
> >>>kernel (loaded via "boot" or from "filesys").  "builtin" modules still
> >>>need to use the link_set mechanism.
> >>
> >>Shouldn't be that hard to put the contructor list address into a
> >>link_set - that would make it easy to get them called for 'built in'
> >>modules.
> >
> >It's not even that complicated. Just provide symbols for start and end
> >of the .ctor / .dtor section. That can be done either using linker
> >scripts or by prepending / appending a small object like crt* does.
> 
> But can you provide symbols for the start/end of each module's portion 
> of the .ctor / .dtor section?  I don't think you can even guarantee that 
> all contributions for a module would be co-located.  And I don't think 
> you would want to call all contructors for all (built-in) modules at the 
> same time, so you'd need a way to identify which entries belong to each 
> module.  This is essentially what the link_set mechanism does today - 
> the net80211 module (and other stuff) each gets its own .ctor section.

You could rename (or maybe name) the modules section to .ctor.module,
then you'd need to add a list of the .ctor.module names into the
linker script to getthem called in the right order.

I think the rename would be enough to get the symbols together.

Other schemes that might work involve doing an initial 'ld -r'
for the module, then processing the output of objdump/nm to generate an
extra object file to link into the output.
I'm not sure whether youcan use a linker script to control an 'ld -r'.

        David

-- 
David Laight: david%l8s.co.uk@localhost