As you might have guessed already, the Linux-libre 4.8-gnu kernel is based on the recently released Linux 4.8 kernel branch, but it contains lots of deblobbing changes for quite a large number of the newly included drivers, in particular those for AMD Radeon Evergreen graphics processing units. Some work was done as well to the internal documentation. With the GNU Linux-libre 4.8 kernel you have 100% freedom when running a GNU/Linux operating system, as the GNU Linux-libre project produces a special version of the latest mainline upstream Linux kernel that is 100% free of proprietary code. Basically, it does not contain any non-free components, and it also disables runtime requests for them.