[DCPM] hierarchies

Neil Williams linux at codehelp.co.uk
Fri Dec 15 15:40:07 PST 2006


On Fri, 15 Dec 2006 23:06:34 +0000
Simon Waters <simon at technocool.net> wrote:

> Neil Williams wrote:
> >
> > Given an existing set of packages A, which packages need to be built
> > *FIRST* in order to eventually build a system to support package set B.
>
> Can you define what problem you are trying to solve, rather than what
> you think you need to do to solve it.

A 'system' (which may be not much more than an ISO image or chroot jail) has a (small) set of packages A and needs a (large) set of packages B. Packages are available elsewhere to go from A to B but these are incompatible with A so each package must be rebuilt using only packages already available in set A. Once successfully built, new packages get included into set A so that you incrementally move closer to a full set B. By following the known dependencies of packages within B, identify the sequence that can build all packages in set B starting from set A. i.e. this is Build-Depends, rather than the binary depends.

The initial set of packages, A, includes a compiler for that system and nothing else - not even a kernel - because it is a cross-build. The script needs to lay out a path from a bare compiler system to a full Gnome environment without requiring any packages that are either not already installed or cannot be successfully built using the packages already installed. So start with packages that depend only on libc6 and tzdata, then move on to packages that need these packages but nothing else, etc.

Additionally, building any package will involve modifying the packages such as to remove unnecessary or unwanted modules thereby modifying the dependency tree on-the-fly. The target is to install the absolute minimum number of packages and/or substitute large packages for smaller ones such as to require the smallest total amount of installation space on the target system whilst still including as much as possible of set B.

--


Neil Williams
=============
http://www.data-freedom.org/
http://www.nosoftwarepatents.com/
http://www.linux.codehelp.co.uk/

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