Linux fragmenting at last?

Dan Walsh, a Red Hat developer working on SELinux, has criticized this move:

For years, critics have claimed that Linux would fragment much like Unix did, and that would be the downfall of the system. So far, Linux has steadfastly refused to fragment in this manner. But now we have a Linux developer saying that the same thing is happening. Red Hat and Novell also appear to be taking different approaches to 3D-enhanced window systems. Novell is pushing Xgl, Red Hat has AIGLX, and Linux users are left wondering when and how all that activity will yield better graphics support for them. At this level, too, it looks like Linux might finally be heading for a breakup.

Or is it? Perhaps we are simply seeing the development community at work.

With regard to SELinux, it is important to note that there is no real consensus, yet, on how the security problem should be solved. SELinux is a powerful system, beyond doubt; it allows the capabilities of users and programs to be specified in great detail. But SELinux is also highly complex, to the point that a large percentage of system administrators find themselves unable to cope with it. The fedora-devel list just had a discussion on how to get administrators to keep SELinux enabled on their systems. One participant, who teaches administration courses, noted:

The point here is not to criticize SELinux; that has been adequately done elsewhere. Instead, the real point is there is not, at this time, any sort of broad consensus that SELinux is the right tool for everybody's security problems. It may turn out that the best solution is to put more effort into making SELinux easier to deal with, but it seems premature to claim that SELinux will be the answer to security problems on Linux. It makes sense, in other words, to spend some time considering other approaches - especially those which are already implemented and relatively stable.

If SELinux is truly a superior solution, that will eventually become clear and users will vote with their keyboards. But to claim, at this point, that SELinux is the only solution and that looking at alternatives hurts the community would be a mistake. This community thrives on choices, and, to an extent, it thrives on competition between related projects. Since the alternatives are all free software, users are able to choose what works for them, and the best ideas (and code) can move from one project to another.

The process would be helped, however, if Novell would pull together the AppArmor source and submit it properly for review and eventual merging into the mainline kernel.

The story with Xgl and AIGLX is the same. There is no real consensus, yet, on how 3D graphics will be best supported in the X window system. So two groups have put together two different implementations, each with its advantages. It is easy to present this story as a classic developer flamewar, but that does not seem to match the reality of the situation. A look at the X.org mailing list, for example, shows Xgl developer David Reveman agreeing to adopt some interfaces put forward by the AIGLX group. Over the long term, the development community will almost certainly coalesce around the approach which seems to work best, but, for now, it is too early to say which one (if either) will be most successful.

If there is a problem here at all, it is that the distributors are being quick to make products out of technology which may not be entirely ready for prime time. Red Hat has operated this way for a very long time; anybody who remembers being pushed into, for example, the ELF or glibc2 transitions by Red Hat Linux upgrades knows that some of that code was a little rough around the edges then. But, by pushing that code out to the users, Red Hat almost certainly accelerated the stabilization process.

What we are seeing now is that Novell wants to get into the same game and put more leading technology into the traditionally conservative (by comparison) SUSE distribution. When things work well, Novell will be able to claim leading-edge features and the code will get wider testing, sooner. There is nothing that requires Novell, as it moves SUSE Linux toward the leading edge, to follow Red Hat's decisions on which approaches to adopt.

The risk is that each distributor's user base will find itself locked in to a different set of still-green technologies, making it harder for the development community to settle on a single choice. In the cases of security policies and 3D acceleration, however, the potential for lock-in seems low; most users will not care about which approach they use, as long as the system works well. So, most likely, those critics who have predicted the death by fragmentation of Linux will have to wait a while longer yet.

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