CUDA Toolkit 13.4 is a vendor release that extends CUDA to Windows on Arm, adds preview support for the Rubin GPU architecture (compute capability 107), and introduces MPS V3, CUDA Compute Fabric Transport (CFT), locality domains, unified-memory residency queries, and a CDMM default on NVIDIA coherent platforms. It also updates CUDA Python, CCCL, CUDA Tile IR, and Nsight tools.1

Context

The release changes several operational boundaries rather than only adding APIs. Windows on Arm becomes a supported CUDA host platform in addition to Linux on Arm; CUDA SDK installers no longer bundle the NVIDIA driver; and on Grace Hopper, Grace Blackwell, and Vera Rubin, the driver defaults to Coherent Driver-based Memory Management (CDMM) instead of NUMA. MPS V3 exposes a scriptable CLI, named server instances, namespaces, TOML configuration, SM partition controls, and cgroup-integrated GPU memory limits.1

Assessment

The most consequential constraint shift is control over shared and disaggregated GPU resources: MPS V3 programmatically partitions compute, memory, and priority; CFT replaces virtual-address mapping of every remote GPU allocation with named endpoints and asynchronous put/get/reduction operations on NVLink; locality domains let applications co-locate SMs and device memory; and unified-memory residency queries expose where managed data resides. These are infrastructure-facing capabilities, not end-user features.1

Caveats

The evidence is a single vendor release note, so performance and portability claims lack independent verification. Rubin support is explicitly a preview for porting before general availability; CFT is available only through the CUDA Driver API and is intended for communication-library developers, with NCCL and NVSHMEM recommended for most developers; and the 92% memory-bandwidth utilization figure for cub::DeviceScan is stated without benchmark configuration. My assessment would change if independent testing showed Windows on Arm parity, if Rubin reached general availability with stable ABI and toolchain commitments, or if CDMM migration caused production regressions on coherent platforms.1