Spring week notes: Chapel/PBT post, ActivityPub pulse, Vite 8

docs/bigscreen-beyond-edid-proof-packet-2026-04-25.md

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+# Bigscreen Beyond EDID Non-Desktop Handling: Proof Packet
+
+Date: `2026-04-25`
+Status: draft; pre-submission; quirk-only patch held; parser proof passed
+Decision gate: Monday evening, `2026-04-27`
+
+## Abstract
+
+A Bigscreen Beyond head-mounted display attached to the `honey` workstation
+reports EDID manufacturer `BIG`, product `0x1234`, and a DisplayID 2.0
+extension header whose primary-use field is `0x07`, corresponding to a
+head-mounted virtual reality display. The required DRM semantic result is
+`non_desktop = true`.
+
+A local downstream quirk patch can produce that result, but a quirk-only
+upstream submission is not presently appropriate. An identical `BIG/0x1234`
+quirk was submitted to `dri-devel` in May 2024, and reviewers directed the
+problem toward DisplayID parsing rather than an EDID quirk table entry.
+
+That parser route now has a positive result: a no-quirk KUnit test on `honey`
+against current `drm-misc-next` passed with this captured EDID and
+`non_desktop = true`. The remaining decision is whether to send a
+regression-test-only patch or to close the upstream submission lane as already
+handled by current upstream behavior.
+
+## Primary Evidence
+
+| Measurement | Value |
+| --- | --- |
+| Host | `honey` |
+| Kernel during capture | `6.19.5-7.xr.el10` |
+| DRM connector | `/sys/class/drm/card0-DP-2` |
+| EDID first 16 bytes | `00 ff ff ff ff ff ff 00 09 27 34 12 d2 04 00 00` |
+| EDID manufacturer/product | `BIG/0x1234` |
+| DisplayID extension prefix | `70 20 79 07 ...` |
+| DisplayID version byte | `0x20` |
+| DisplayID primary-use byte | `0x07` |
+| Primary-use interpretation | head-mounted virtual reality display |
+| Durable local capture | `Jesssullivan/Dell-7810:data/captures/honey/bigscreen-beyond-edid-2026-04-25.txt` |
+| No-quirk KUnit proof | `Jesssullivan/Dell-7810:data/captures/honey/bigscreen-displayid-kunit-2026-04-25.txt` |
+| KUnit base | `drm-misc-next` commit `03af6c3afc48` |
+| KUnit result | `drm_test_connector_edid_displayid_hmd_primary_use` passed |
+
+The current evidence proves the device identity, the DisplayID primary-use
+claim, and the upstream parser result for this EDID in a no-quirk kernel-tree
+test. It does not yet prove a live connector-property result from an
+unmodified upstream kernel booted on this hardware.
+
+## Structural EDID Preflight
+
+A local byte-level preflight of the captured EDID produced the following
+results:
+
+| Check | Result |
+| --- | --- |
+| Total length | 256 bytes |
+| Base EDID block checksum | `0x00` |
+| DisplayID extension block checksum | `0x00` |
+| DisplayID section checksum | `0x00` |
+| DisplayID declared payload length | 121 bytes |
+| First DisplayID block | tag `0x22`, revision `0x09`, payload length 40 bytes |
+| First DisplayID block bounds | valid within the declared DisplayID section |
+| Static parser expectation | `non_desktop = true` |
+
+This preflight showed that the captured EDID satisfies the structural
+assumptions that current `drm-misc-next` appears to require before
+`update_displayid_info()` can observe DisplayID version `0x20` and primary use
+`0x07`. The subsequent KUnit proof confirms that parser expectation in-tree.
+
+## Prior-Art Record
+
+The relevant public history is a May 2024 `dri-devel` thread and the associated
+freedesktop issue:
+
+- Sefa Eyeoglu submitted a `drm_edid.c` quirk adding `BIG/0x1234` to the
+  non-desktop table on `2024-05-17`.
+- Jani Nikula requested that the issue include EDID evidence and possibly
+  `drm.debug=14` dmesg so that the quirk would remain explainable later.
+- Sefa submitted a revised patch referencing freedesktop issue 39.
+- Philipp Zabel observed that the EDID's DisplayID block already describes the
+  primary use as a head-mounted virtual reality display and that
+  `update_displayid_info()` should use this to set `non_desktop`.
+- Sefa noted EDID conformance failures in the DisplayID data blocks.
+- Jani stated that the DisplayID header primary-use value should be sufficient
+  for classification.
+
+Source links:
+
+- <https://lists.freedesktop.org/archives/dri-devel/2024-May/454216.html>
+- <https://lists.freedesktop.org/archives/dri-devel/2024-May/454226.html>
+- <https://lists.freedesktop.org/archives/dri-devel/2024-May/454244.html>
+- <https://lists.freedesktop.org/archives/dri-devel/2024-May/454248.html>
+- <https://lists.freedesktop.org/archives/dri-devel/2024-May/454255.html>
+- <https://lists.freedesktop.org/archives/dri-devel/2024-May/454416.html>
+- <https://gitlab.freedesktop.org/drm/misc/kernel/-/work_items/39>
+
+## Technical Implication
+
+The proposed upstream artifact cannot be framed as a novel EDID quirk. The
+review record establishes a stronger expected invariant:
+
+```text
+DisplayID version 2.0
++ primary-use field HEAD_MOUNTED_VR
+=> drm_display_info.non_desktop = true
+```
+
+Current `drm-misc-next` contains the intended decision point in
+`update_displayid_info()` in `drivers/gpu/drm/drm_edid.c`. The DisplayID
+iterator path in `drivers/gpu/drm/drm_displayid.c` exposes the extension
+version and primary-use byte. The relevant constants are
+`DISPLAY_ID_STRUCTURE_VER_20` and `PRIMARY_USE_HEAD_MOUNTED_VR`.
+
+The parser-path result is now positive. The technical question is no longer
+whether a quirk is needed for this EDID in current `drm-misc-next`; it is
+whether a small regression test is valuable upstream documentation for this
+previously disputed hardware case.
+
+## Candidate Paths
+
+### Path A: Parser Or Regression-Test Submission
+
+This is the preferred technical route.
+
+1. Current `drm-misc-next` has been evaluated against the captured Bigscreen
+   Beyond EDID by KUnit on `honey`.
+2. Because upstream sets `non_desktop`, retire the local quirk lane and
+   document the downstream cleanup.
+3. If submitting upstream, prefer a regression-test-only patch with references
+   to the 2024 review thread and freedesktop issue 39.
+4. Do not submit a parser fix unless a separate failure is found.
+5. Submit any patch with references to the 2024 review
+   thread and freedesktop issue 39.
+
+### Path B: Quirk With Explicit Rebuttal
+
+This path is not preferred. It is acceptable only if Path A produces evidence
+that the parser path cannot classify the connector correctly.
+
+The submission would need to include:
+
+- full EDID evidence;
+- the upstream failure mode;
+- the downstream result;
+- a direct explanation of why the DisplayID header should not be relied upon
+  for this EDID;
+- `drm.debug=14` dmesg if the failure mode is not self-evident.
+
+### Path C: Prior-Art Coordination
+
+Before any public patch that supersedes or reopens the 2024 work, contact Sefa
+Eyeoglu if feasible. Ask whether they prefer to resend, co-author, review, or
+be credited. Add credit trailers only with explicit consent.
+
+Path C can run in parallel with Path A. It should precede any public v1 that
+uses Sefa's prior submission as a foundation.
+
+## Verification Routes
+
+### Offline Parser Proof
+
+Use the captured 256-byte EDID as a fixed test vector. This route is complete
+for the current question: `drm_test_connector_edid_displayid_hmd_primary_use`
+passed against `drm-misc-next` commit `03af6c3afc48` without any `BIG/0x1234`
+quirk.
+
+Required output:
+
+- kernel tree and commit;
+- test vector hash or stored EDID path;
+- function or test target exercised;
+- observed `non_desktop` result: true;
+- whether any new patch is required.
+
+### Live Kernel Proof
+
+Boot or run an unmodified upstream-equivalent kernel on a host with the
+headset attached.
+
+Required output:
+
+- kernel build identity;
+- connector path;
+- raw EDID;
+- connector property result;
+- dmesg excerpt if the result differs from the parser expectation.
+
+### Runtime Context Proof
+
+This route is explanatory rather than necessary for the kernel decision. It may
+show why the classification matters to Monado, DRM leasing, and XoxdWM, but it
+must not be used as a substitute for the DRM parser proof.
+
+## Hardware Required
+
+- Original Bigscreen Beyond headset reporting `BIG/0x1234`.
+- Linux host with a DisplayPort path to the headset.
+- GPU and DRM stack exposing the headset connector through `/sys/class/drm`
+  and `/dev/dri`.
+- Ability to read EDID and connector properties without changing compositor or
+  service state.
+- Optional OpenXR/Monado stack for runtime context after the kernel property is
+  verified.
+
+## Submission Rules
+
+- Do not send the current quirk-only patch before the `2026-04-27` decision
+  gate.
+- Do not omit the 2024 thread from the patch rationale.
+- Do not use `Reported-by`, `Suggested-by`, `Reviewed-by`, or
+  `Co-developed-by` without explicit permission.
+- Do not include the Bigscreen Beyond 2e product ID `0x5095` unless separate
+  evidence is captured.
+- Do not claim unpatched upstream runtime behavior until it has been measured.
+- Do not include lab-private topology, credentials, or host-access details in
+  public kernel email.
+
+## Current Conclusion
+
+The strongest submission path remains Path A, with Path C running in parallel
+if a public patch is sent. Path A now says current upstream parser behavior is
+correct for the captured EDID. A quirk-only v1 would repeat the prior public
+patch and would likely receive the same technical objection. The next useful
+artifact is either a regression-test-only patch or a documented decision to
+retire the downstream quirk carry.