Gallium3D

Gallium3D is a driver framework within the Mesa 3D Graphics Library that provides a unified, API- and hardware-agnostic interface for 3D graphics drivers. It separates the front-end graphics APIs (such as OpenGL and OpenGL ES) from the back-end hardware drivers, enabling multiple API implementations to share core driver code. This abstraction aims to reduce duplication and improve portability and maintainability of drivers across different GPUs.

Architecture in Gallium3D centers on the concepts of state trackers, pipes, and screens. State trackers are the API-specific front ends that translate API calls into Gallium pipe commands. The hardware drivers implement the pipe interface for a particular GPU family, providing the low-level rendering functionality. Screens represent the actual device context. The framework also includes software renderers, such as llvmpipe and softpipe, which implement Gallium interfaces on the CPU for testing or virtualization scenarios.

History and scope: Gallium3D emerged in the Mesa project in the late 2000s as an effort to replace many older DRI-backed drivers with a common backend. It quickly became the foundational architecture for a broad range of Mesa drivers on Linux, enabling more efficient driver maintenance, feature support, and performance improvements across GPUs.

Notable drivers: Within the Gallium framework, Intel GPUs commonly use i965g or iris backends, AMD/ATI GPUs use r600g or radeonsi, and NVIDIA GPUs have a nouveau backend. Other examples include svga for VMware virtual GPUs and software renderers like llvmpipe.

Impact: Gallium3D significantly influenced Mesa driver design by emphasizing modularity, code reuse, and portability. It remains a core aspect of Mesa’s driver system, though ongoing development has introduced newer pipelines and backend variations over time.