The Software Freedom Conservancy has stated in a blog post that they believe Canonical’s work to add ZFS to Ubuntu violates the GPL license. ZFS is a Unix file system that has been gaining popularity in recent years that is licensed under the Common Development and Distribution License (CDDLv1). Canonical’s decision to add this file system to Ubuntu has been well received, and it has been possible to install it since version 15.10.
Canonical recently announced that a binary distribution of ZFS would be included in Ubuntu 16.04, this decision is what sparked the SFC’s claim that they are violating the GPL license for the Linux Kernel. The conservancy has outlined their claim in great detail on their blog.