Linux: Cleaning the Kernel Headers

David Woodhouse offered a collection of patches aimed at cleaning up Linux kernel headers, explaining that he maintains the Fedora glibc-kernheaders package and has found the process of syncing with the latest kernel to be unnecessarily tedious. Linus Torvalds acknowledged the effort, noting that he preferred to wait until early in the 2.6.18 development cycle before merging the patches as things tend to break, "yeah, people shouldn't include kernel headers, but if they didn't, this patch wouldn't matter. And when they do, patches like this tends to show some strange app that depends on the current header layout.. Gaah."

David responded, "Well, yes, but we all know that people _have_ to include kernel headers. We can't just bury our head in the sand and say 'they mustn't do that'. The kernel headers contain all the juicy stuff like structure definitions and ioctls which you _need_ in order to communicate with the kernel. The problem is that we don't actually have any _discipline_ about how we throw our kernel headers over the wall. We never even _think_ about how usable they are in userspace, or how what we're doing will affect userspace."

Linus was quick to retort, "if this is work to try to make kernel headers generally palatable to user space, I'm not going to apply it at all. Not now, not early in the 2.6.18 sequence, not EVER. Because that's not a goal I believe in for a moment." He then went on to explain, "in contrast, if this is work to make it eventually _easier_ for _library_ people to decide to upgrade their kernel-related information, I'm ok with it. But that 'target audience' part really is very very important. The target audience should NOT be applications including kernel headers. The target audience should be distributions and library maintainers."

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