AC_CONFIG_SUBDIRS

[Bob Rossi]

Hi,

I'd like to use AC_CONFIG_SUBDIRS, but would like to understand more
clearly what it does. I have a setup where you check out a project and
then you have a top-level ./configure script.

When you run the top-level configure script, it determines what libraries you 
need to build the project, and then downloads the .tar.gz dependency, untars
it, and configures it. Currently I ./configure the sub projects manually by
calling the sub projects ./configure directly. However, using AC_CONFIG_SUBDIRS 
might be better, because I think it'll pass down the top-level configure 
options 
to the subproject.

I'm wondering if there is a way to get AC_CONFIG_SUBDIRS to work, even
though the configure script or sub directory isn't available until
./configure is run and it determines what libraries to download. 

I'm wondering how options are passed down through AC_CONFIG_SUBDIRS from
the top-level Makefile. Can you tweak the options for each sub project?
I'd like to be able to cross compile, so it'd be nice if that was passed
down only when the cross compile commands were given at the top level.
However, I'd also like to have shared libraries, except for maybe one
particular package. So for that package, I'd like to override the
top-level option. 

How are these things accomplished? I'm currently doing it by simply
calling the ./configure script manually from within the top-level
configure. However, I have to explicitly put in all the options that I 
wanted to flow down from the top-level Makefile. The other option is to
use the AC_CONFIG_SUBDIRS option and explicitly remove the options that
I do not want to flow down.

What should I do? Any advice from people that have solved this problem
before?

Thanks,
Bob Rossi