Upstream PR 3002 Unsupported Vertex Conversion

Upstream PR #3002 — Convert vertex attributes the device cannot consume

Upstream work · Actionable research · Research and retired work

Current disposition — November 1, 2026

Reviewed: November 1, 2026. Fork source: b7140848 (full SHA b71408480a3a979a9c584663e1d1f400904c8bb7). Latest stable checked: v0.8.136-0-g458730bf5373, September 30, source 458730bf5373f1f0d027450fef7443e3af7a3ae1. GitHub state, branch recommendation, source presence and release availability are separate facts. See current status and release versus main.

Current field	November 1, 2026 observation
GitHub source	Upstream #3002
GitHub state / draft	Open / No
Current head	873181abd5dbb51a35c37321d551d75d815098f9
Originally reviewed head	873181abd5dbb51a35c37321d551d75d815098f9
Last metadata update (UTC)	2026-10-18T20:59:11Z
Head versus original review	Same recorded head; metadata/state updates do not indicate a new proposal-code head.
Current action	Open proposal; refresh integration and focused tests before handoff.
Fork/release availability	This upstream proposal’s GitHub state does not establish full fork/release inclusion. The historical overlap below is scoped to its recorded fork baseline; use the current feature register for delivered fork behavior.

The current head matches the recorded September review head. Later updated_at metadata does not establish changed proposal code. The original fork overlap remains a dated source comparison, not a fresh integration or native qualification result.

This refresh checked GitHub identity/state and the specific source boundaries named above. It did not rerun native games, XISO timings or integration qualification. Historical performance claims remain attached to their original heads.

Historical review — September 21, 2026

The review below is preserved as written, including its original state, head, fork baseline and proposed handoff. Its present-tense statements apply to that dated review; the current disposition above governs today’s action.

← Upstream Work

Field	Value
Upstream PR	xemu-project/xemu#3002
State at 2026-09-21 audit	Open
Reviewed upstream head	873181abd5dbb51a35c37321d551d75d815098f9
Last upstream update seen	2026-09-06
Reviewed upstream base	f9b14039e5bb56ae2d8f028e31e7cc19f13f7e12
Fork baseline	82d04d84bdb3de956f20c3537e1da2cece0e8da2
Relationship	Complementary feature; no equivalent downstream conversion claimed
Related fork work	Vertex lifetime work and prewarm format admission
Contribution priority	Medium
Upstream contact status	No comment posted by this audit.

Summary

The PR converts guest vertex formats that the selected Vulkan device cannot consume directly.

Upstream scope

Device format capability determines whether an attribute can remain native or must be converted into a supported host format.

Corresponding fork work

Downstream prewarm admission learned to check VK_FORMAT_FEATURE_VERTEX_BUFFER_BIT; #85/#89 cover source-range correctness and lifetime. Those mechanisms complement conversion but do not implement it.

Difference that must remain explicit

Rejecting an unsupported prewarm recipe is not the same as converting a demanded draw. Capability checks, conversion selection, destination layout, and pipeline key identity must agree.

Transferable regression and review cases

• Controlled format-properties callback selects native versus converted path.
• Unsupported format never reaches pipeline creation with an invalid vertex format.
• Conversion preserves normalized/scaled/integer semantics and provoking-vertex behavior.
• Source stride/offset and destination stride/offset are distinguished.
• Converted buffers obey active-draw lifetime rules.

Suggested upstream handoff

Offer capability-admission and source-range tests. State that conversion remains upstream functionality.

Claims this page does not support

• It does not prove the upstream branch merges cleanly with current upstream.
• It does not prove a native correctness or performance result unless a linked exact-head run says so.
• It does not transfer favorable performance percentages between hardware, renderers, games, or source heads.
• It does not authorize posting a comment or review upstream.

Before sending anything upstream

• Refresh the PR state, head SHA, description, changed files, and newest review comments.
• Recheck the corresponding fork implementation on current main.
• Run or cite the narrow regression on an exact source state.
• Verify every public link and remove private paths, captures, game data, credentials, and internal logs.
• Phrase source concerns as source concerns and reproductions as reproductions.
• State the uncovered behavior and evidence limit.
• Add the posted URL and upstream response to this page.

Tracking log

Date	Upstream head	Action	Result
2026-09-21	873181abd5db	Fork/upstream source comparison recorded	Handoff prepared; nothing posted

References

• Upstream PR #3002
• Fork repository
• Upstream Work
• Pull Request Lessons