The author successfully enabled peer-to-peer (P2P) data exchange on NVIDIA CMP 90HX mining cards. Previously, these cards were software-restricted from direct memory access, forcing data to route through system RAM, which significantly slowed down operations like running large language models across multiple GPUs.
By analyzing the NVIDIA Open Kernel Module (version 610.43.03), the author discovered internal mechanisms intended for testing and debugging. These include flags such as ForceP2P, RMForceP2PType, and RMDisableFeatureDisablement, which allow overriding hardware-specific restrictions that label P2P as 'not supported' for the CMP 90HX.
The process involved modifying the driver to force-enable P2P capabilities. Even though the GPU System Processor (GSP) initially reported P2P as unsupported, the author utilized the built-in override mechanisms left by NVIDIA engineers to bypass these checks and establish direct memory mapping between the cards.
This modification allows one GPU to access the memory of another directly via the PCIe bus without using system RAM as an intermediary. The author confirmed that the system correctly identified all five CMP 90HX cards and successfully established P2P communication after applying the driver patches.
