Thanks – again – to Tomas Pruzina, there is a Kernel 4.10 patch for new beta driver 378.09, and details are here: https://devtalk.nvidia.com/default/topic/988958/linux/-patch-378-09-4-10-0-rc4-patches/

I have applied this to 378.09 on Kernel 4.10-rc4, and can confirm that it now compiles OK..

.............................
/home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia/svnp01_linux.o
ld -r -o /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-modeset/nv-modeset-interface.o /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-modeset/nvidia-modeset-linux.o
 Building modules, stage 2.
 MODPOST 4 modules
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-drm.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-drm.ko
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-modeset.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-modeset.ko
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-uvm.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia-uvm.ko
 CC /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia.mod.o
 LD [M] /home/rgadsdon/kernel/NVIDIA-Linux-x86_64-378.09-patched/kernel/nvidia.ko
make[2]: Leaving directory '/usr/src/linux-4.10-rc4'
make[1]: Leaving directory '/usr/src/linux-4.10-rc4'

As with the 375.26 patch, the hotplug functionality is simply ‘bypassed’ in the patch..

Robert Gadsdon.   January 19, 2017.