Just updated the test system to Kernel 4.15-rc3, and the GPL issue for NVIDIA drivers has been fixed, as mentioned – vaguely – in the brief details here:  http://lkml.iu.edu/hypermail/linux/kernel/1712.1/01379.html.

NVIDIA driver 384.98, with the first 4.15 patch (see http://rglinuxtech.com/?p=2134 ), now compiles and loads OK:

 ........
Building modules, stage 2.
 MODPOST 4 modules
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia-drm.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia-drm.ko
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia-modeset.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia-modeset.ko
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia-uvm.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia-uvm.ko
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-384.98-415/kernel/nvidia.ko
make[2]: Leaving directory '/usr/src/linux-4.15-rc3'
make[1]: Leaving directory '/usr/src/linux-4.15-rc3'

Robert Gadsdon.   December 10, 2017.