GNU Linux-libre for those that don't know is the FSFLA effort to de-blob the mainline Linux kernel by removing support for loading binary-only modules as well as stripping out drivers or portions of driver code that rely upon closed-source/binary-only firmware/microcode images, which is quite common among newer hardware.
As with most kernel cycles, the graphics drivers are what gets most criticized for their lack of freedom.
Alexandre Oliva of the Free Software Foundation Latin America wrote, "GPU drivers remain as the most frequent offenders for new blobs: i915, adreno, amdgpu and radeon all introduced new blob requirements for (presumably) previously-unsupported hardware variants."
A new driver to the 4.10 kernel, st_fdma, also requires binary blobs. The st_fdma driver is for ST Microelectronics FDMA DMA Engine support.
The GNU Linux-Libre 4.10 release announcement can be read in full via the FSFLA mailing list.