It must be maddening to believe you command developer loyalties and lead legions worldwide, then watch developers flock to the Linux kernel. Maddening, that is, if you're Microsoft. Why does Microsoft say its patents cover Linux, while at the same time reaching out to other open source code projects? It's the Linux kernel development process.Imagine you're Microsoft and you've spent years struggling to get Windows Server 2008 out the door and will be struggling afterward to add server virtualization? Then along comes Linus Torvalds and his merry band and they add KVM to the Linux kernel over the course of a few months, release a new kernel for review every 2 to 3 months, and attract thousands of developers interested in the new features. Linux had both VMware and Xen hypervisors running on it just fine. Now it's got another one freely available inside the kernel. It must feel in Redmond like Linux steals from the rich to give to the poor. It's not just the dollars at stake. Microsoft has understood better than most the value of developer loyalty. Windows bloomed as a platform as Microsoft attracted thousands of third-party developers to write for it. It provided tools, technical conferences, and otherwise skillfully cultivated its developer community, letting it leverage Windows.

Microsoft itself is an essentially developer culture, not an Apple consumer culture or an IBM enterprise culture. When it sees developers flocking to a new standard, it reacts with jealousy and defensiveness. I'm not thinking of Linux this time, but the reaction to Sun Microsystems' Java. As the Internet grew in importance, Java seemed to be the right language at the right time.

Microsoft reacted by changing Java on Windows to make it run better there, and, incidentally, to divide Java developers into those in the Windows camp and those outside it. Sun sued, because its Java license says if you adopt part of Java, you adopt all of it. That kept it a common standard on all platforms.

Microsoft e-mail disclosed during the discovery phase of the trial that it had wanted to drive a wedge into the unified world of Java and gain ownership over part of it. Microsoft settled with Sun out of court for about $200 million.

Later, Sun sued Microsoft for anticompetitive behavior in 2002 and as Sun fell on lean times, the two again settled out of court, this time for $1.9 billion.

The lesson I drew from this experience was that Microsoft was on shaky legal ground when it did what it did with Java, but it couldn't help itself. If there was something that developers wanted, then Microsoft needed to own it, or at least "own" the Windows developers devoted to it.

Now the Linux kernel development process, which has been under way for 16 years, represents the largest, most complicated ongoing software development project in the world, with the possible exception of Windows itself. It's moving fast, fluidly filling niches that Microsoft in the past had staked out. It's leading in virtualization, in virtual appliances, in mobile devices. It's threatening Windows on a number of fronts.

Microsoft doesn't want to jeopardize its huge customer based by attacking open source code in general and refusing to work with it. See Nick Hoover's recent interview with Microsoft's Bill Hilf to get a sense of the tightrope it must walk.

But all those developers contributing code to Linux, that loose but disciplined kernel maintainer process, those frequent releases of code -- it's frustrating. There's no single point of attack. And those tough competitors -- IBM, Google, Red Hat -- they all employ kernel developers, but they're keeping their hands out of the pot. See Linux Kernel Maintainers: Accountable To All, Beholden To None. Why can't they slight Linux' reputation by giving it a little vendor coloration, a little corporate self interest, a tarnish? Microsoft's "The Truth About Linux" advertising campaign didn't seem to affect the Linux adoption rate. Nor can Microsoft bad-mouth open source to such an extent that it sounds like it refuses to interoperate with it. Customers get concerned.

So Microsoft has started talking about its patents and, coincidentally, supplying former Microsoft execs to firms who are willing to sue Linux for patent infringement. If you can't own the right technology, maybe you can assert ownership rights other ways.

Linus Torvalds doesn't think the kernel development process can be stopped. Even if a court upheld a patent case against it, open source developers would flock to the opportunity to rewrite the code, document it, and Linux would continue on its merry way. But for Microsoft, you know nerves are getting frayed and options are running out when it starts resorting to talk of patents.