SmartOS (based on IllumOS) released - with KVM

They are, separately, independent works, of course. However the KVM announced here is not the stock Linux KVM, but one ported (with significant effort) to work within Illumos. I thought that was reasonably obvious from the blog post. ;) I.e. it is a derived work of Linux KVM and Illumos.

To quote the blog post: "just getting it to compile in any meaningful form would take significant effort", "KVM is so tightly integrated into the Linux kernel", "hard to know when to pull in the Linux implementation of a particular facility or function versus writing our own or making a call to the illumos equivalent (if any)". The blog post seems to be fairly explicit about the fact that much judgement, work and creativity was needed to solve a number of problems. It's very hard to think software copyright wouldn't apply to the apparently substantial amount of code they say they had to modify, re-write and write.

My understanding is that the bar to a work being derived is pretty low. I.e. small patches with obvious, no-other-way fixes might not be worthy of copyright, but if there's any room for creativity then that implies that the work does fall under copyright. Further, when you have a one body of code dependent on a very *specific* other piece of code, then my understanding is that the dependent code derives from the other. The Illumos KVM patch seems, by the blog post, to depend on both the Linux KVM and IllumOS code.

That said, the CDDL and the GPL are both free software licenses, and if all the copyright holders concerned are all happy, then there needn't be a problem.