Thanks to loqs, there is now a viable patch for NVIDIA and Kernel 4.20.

I applied the patch to driver 415.18, and tested with Kernel 4.20-rc3, and the driver compiles cleanly, now:

...........................
ld -r -o /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-modeset/nv-modeset-interface.o /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-modeset/nvidia-modeset-linux.o
Building modules, stage 2.
MODPOST 4 modules
CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-drm.mod.o
LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-drm.ko
CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-modeset.mod.o
LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-modeset.ko
CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-uvm.mod.o
LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia-uvm.ko
CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia.mod.o
LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-415.18-420/kernel/nvidia.ko
make[2]: Leaving directory '/usr/src/linux-4.20-rc3'
make[1]: Leaving directory '/usr/src/linux-4.20-rc3'
.....................

– and everything appears to be working OK (KDE/Plasma etc..).

A link to the patch can be found in the comment under my previous article ( https://rglinuxtech.com/?p=2440 ).

Robert Gadsdon.  November 22, 2018