NOCL: Mesa’s OpenCL-on-CUDA Effort Advances as a New Compute Option for NVIDIA Linux Driver

# What NOCL is NOCL is a Mesa Gallium3D driver that implements OpenCL on top of NVIDIA's CUDA driver API. The project began under the name CLUDA and has been in development for about a year. Its purpose is to provide an open-source path for running OpenCL workloads while using NVIDIA's proprietary Linux driver stack as the underlying execution layer.

# How it works NOCL is a compute-only Gallium driver. It relies on NVIDIA's CUDA driver API to submit work to NVIDIA hardware and uses the NVIDIA PTX intermediate representation for kernels. The driver is designed to pair with Rusticl, and it leverages PTX for the code path between Mesa and the NVIDIA driver.

# Why this matters NOCL offers a different OpenCL implementation than NVIDIA's proprietary OpenCL driver. According to the development notes, NOCL supports a larger set of OpenCL extensions than NVIDIA's closed driver. That makes NOCL useful for two concrete purposes: performance comparisons against NVIDIA's proprietary OpenCL implementation, and as a development exercise around working with the NVIDIA PTX IR.

# Recent progress and visibility Karol Herbst presented the latest NOCL developments at XDC 2026 in Toronto. The NOCL merge request for Mesa remains open and is tracked as an active ticket. The project is active in Mesa development discussions and available for review and testing by those following Mesa's compute stack.

# Technical implications beyond OpenCL Work on NOCL and particularly PTX-to-NIR support has implications outside pure OpenCL compatibility. PTX-to-NIR conversion is identified as an important component for other projects, for example enabling DLSS-related work in the NVK Mesa driver. That means improvements made for NOCL could enable better interoperability or feature parity in other parts of the open-source graphics and compute ecosystem.

# Who should follow NOCL

• Developers wanting an open-source OpenCL pathway on NVIDIA hardware for Linux.
• Engineers comparing OpenCL runtimes for performance or extension coverage.
• Contributors working on PTX-to-NIR tooling or on NVK/DLSS integration efforts.

# Current status and next steps NOCL is functional and showing useful behavior when paired with Rusticl and NVIDIA's driver. The merge request is still open in Mesa, so the code is not yet fully merged upstream. Interested parties can watch Karol Herbst's XDC 2026 presentation for a developer-focused update and follow the Mesa merge request ticket to track changes and review the code.

# Practical takeaway NOCL presents a practical, source-open option for running OpenCL on NVIDIA hardware via the proprietary CUDA driver. It expands extension coverage relative to NVIDIA's closed OpenCL driver and advances PTX-to-NIR tooling that will be relevant for other Mesa driver work.