More and more Debian source packages offer extra functionnality, besides building their regular binary packages. For instance, the source packages for gcc and binutils allow you to build cross-compilers, and emdebian offers tools for (cross-)building stripped-down versions of some source packages.

Debconf-src is a (mockup) proposal for standardizing access to such extra functionnality. It consists in a dpkg-buildpackage wrapper, called debconf-buildpackage, which allows its user to access alternative build configurations through Debconf questions.

It should be noted that debconf-buildpackage configures the source package only through environment variables, and will usually use its own Debconf database rather than polluting the system's one. Effort has been made to respect the debconf namespace nonetheless.

A preliminary debconf-src package is available in the repository, with manual pages documenting debconf-buildpackage and the interface. Feel free to have a look and send me your comments.