CR Request for WebGPU and WebGPU Shading Language - webgpu / WGSL

[tidoust]

Document title, URLs, estimated publication date

Two specs to transition:

• WebGPU: https://www.w3.org/TR/webgpu/
• WebGPU Shading Language: https://www.w3.org/TR/WGSL/

Note: The source of the specifications to publish as CR is maintained in a dedicated milestone-0 branch in the repository. The main branch contains further updates that will not be part of this snapshot.

No specific deadline for the publication date. Whenever transition is approved.

Abstract

• WebGPU: "WebGPU exposes an API for performing operations, such as rendering and computation, on a Graphics Processing Unit."
• WGSL: "Shading language for WebGPU."

Status

• WebGPU: https://www.w3.org/TR/webgpu/#sotd
• WGSL: https://www.w3.org/TR/WGSL/#sotd

The group intends to switch to the "Living Recommendations" mode for both specifications once the proposed charter has been reviewed by the AC and approved. If the specifications get published under the current charter and exit criteria need to be specified, the idea would be to use regular exit criteria, like:

• The API/shading language is implementable on top of modern GPU system APIs, such as Microsoft's Direct3D 12, Apple's Metal, and Khronos's Vulkan.
• The API/shading language has at least two independent, interoperable implementations of every feature defined in the specification, where interoperability can be verified by passing open test suites, and two or more implementations interoperating with each other.
• The API/shading language has an open test suite of every feature defined in the specification.

Minimal CR duration: 2 months.

Link to the group's decision to request transition

See resolution during last F2F. The group has resolved pending "milestone 0" since the F2F, also see the CR tracking issue

Changes

First CR

Requirements satisfied

Dependencies met (or not)

Normative dependencies are established standards with one exception: WebGPU specifies the integration with WebCodecs to process media frames, and WebCodecs is still a Working Draft at this stage. The VideoFrame interface at the core of this integration is stable and implemented across browsers already.

Wide Review

• For horizontal reviews, see Seek horizontal reviews gpuweb/gpuweb#2531
• For messages sent to relevant groups, see Criteria for pushing the WebGPU and WGSL specification to Candidate Recommendation gpuweb/gpuweb#3107 (comment)

An issue was raised during PING review on the fingerprinting surface of the API (gpuweb/gpuweb#3101). The group reduced the fingerprinting surface to 5 bits and documented the mitigations that were put in place and the rationale in the issue. This issue is still under discussion in PING.

Issues addressed

All issues at milestone 0 have been addressed.

Formal Objections

None

Implementation

Implementations of WebGPU and WGSL are shipping or are about to ship in major browser codebases:

• shipped in Chromium (behind a flag on Linux)
• behind flags in Firefox and WebKit

The group maintains a conformance test suite (no implementation report available today)

Patent disclosures

https://www.w3.org/groups/wg/gpu/ipr/

[plehegar]

We're checking with the Privacy WG regarding gpuweb/gpuweb#3101 .

[plehegar]

Latest horizontal reviews date back to 2022 and there has been a lot of changes since then. Were the latest substantive changes reviewed?