/host-software/nvidia-gpu-drivers
NVIDIA GPU Drivers
The NVIDIA GPU drivers mediate the interaction between host programs or the host operating system and the GPU device. The primary interfaces to the GPU drivers for applications are, in order, the CUDA Runtime API and the CUDA Driver API .
The CUDA Toolkit. The NVIDIA GPU Driver (highlighted), is the only component that communicates directly with the GPU. Adapted from the Professional CUDA C Programming Guide.
NVIDIA has released the source for their Linux Open GPU Kernel Module .