If I take a chapter of a textbook, modify it to be a standalone volume in a collection of books and start distributing it, I am distributing a derived work of t

If I take a chapter of a textbook, modify it to be a standalone volume in a collection of books and start distributing it, I am distributing a derived work of the original book, not a derived work of the collection of books. The latter constitutes an aggregation and unless there is some license (superseding doctrine of first sale in the case of books) that prevents it from being redistributed with such things, it is perfectly okay to do that. Similarly, the original code was taken from OpenSolaris and was adapted for Linux. No matter how we change it, it is a derived work of Solaris. Furthermore, it is distributed as part of a mere aggregation, which is okay with OSS under the OSD and also okay with the GPL under the GPL FAQ. The only time you can claim a combined work is formed is when the module is loaded into a running kernel, but the GPL does not restrict non-distribution and the kernel with the module loaded into it is not being distributed. As for removing it from the Linux kernel, given that it is an entire storage stack between the block layer and VFS, you would need to replace everything there (including the disk format), but yes, you would have a working system. As for all calls to Linux kernel symbols, those are provided to LKM so that they can function and they cannot function without it. There are symbols not provided at all, symbols provided only to GPL software and symbols provided to everyone. ZFS only uses the last group, which is intended for use by non-GPL software. You can design software to load a LKM from an arbitrary. FreeBSD had done that with Windows kernel modules for wireless drivers at one point. Wine does that for certain Windows drivers that do copy protection. There is nothing stopping you from creating a kernel under a difference license that loads modules in the LKM format of a given Linux kernel. Although the usual case is to port the code to another kernel's own LKM implementation. Attorneys with whom I (and apparently Canonical too) have spoken think this is okay.