In many situations, open Source software developers need to deal with the maintenance of patches. Examples include :
- Unofficial versions of the linux kernel, where specific patches are applied (e.g. Xen kernel, openvz kernel, ..) and need to be constantly forward-ported to the latest kernel when it is released
- Distribution-specific changes (e.g. Ubuntu-specific changes to debian packages).
Maintaining one big diff file for all changes would clearly quickly become unmaintanable, so it looks like different approaches are now widely used instead :
- Maintaining stacks of patches, using specialized tools such as quilt.
- Using distributed VCS tools such as git.
How to survive with many patches describes the use of quilt. Here is some background :
“Andrew Morton originally developed a set of scripts for maintaining kernel patches outside of any SCM tool. Others extended these into a suite called quilt.
It looks like distributed VCS tools have now superceded quilt, as far as pure software development is concerned (linux kernel, etc.). But quilt remains very popular for maintaining distribution-specific changes to packages. Indeed, as distribution packages live outside a SCM tree, it is important to have mechanisms to apply distribution-specific changes to the upstream source packages. And this is where quilt comes to the rescue. Ubuntu packaging guide describes the use of quilt in debian’s packaging system. Such a simple system is clearly awesome, and the more I understand how the Open Source communities organize themselves, the more it makes me realize how technically advanced the Open Source world is compared to the corporate world ! No matter how much you might have heard that tooling is unimportant, the reality is that tools are important. Tools enable complex collaboration, and this is clearly an area where Open Source excels.
