M2-USBGUARD-01 — ready for owner device test

Superseded as the immediate next test by M2-USBACM-01 at the owner's request to combine enumeration and logging. This image remains an untested diagnostic fallback; the procedure below is its historical handoff.

2026-09-09, #23/#27 prerequisite under active M2 #28, baseline de1a6d0. Offline validated; not flashed or hardware tested.

/home/luca/Dokumente/Code/Y2Linux/out/m2-usbguard-01/BOOTIMG.img

1,097,728 bytes; SHA-256: e4078583ab53bd7e6388c94a357023fe8a7504ccc5a7499341cf72287ecd19b5.

Screen/build M2-USBGUARD-01, Linux 6.18.0-y2-m2-usbguard1. Exact diagnostic contract.

Purpose

Your CHRDET photos show successful PMIC detection in both reported startup conditions. With USB connected at startup, PHY6a=BE causes the wake guard to refuse before writing. The previous screen concealed the original guard inputs with unread zero-filled wake data.

This candidate preserves the original MAC/PHY/DMA/IRQ-enable rows when the early wake guard refuses. Unread fields display dashes; successful wake retains its before/after rows. There is no change to register accesses, guards or the cached 260-byte snapshot. Existing guarded PHY6a release remains possible under its proven passive-state conditions. No new PHY/PMIC/clock/VBUS/MAC/DMA write.

Validation

• One clean pinned Linux 6.18 / Clang 20.1.8 build, zero compiler warnings/errors.

  All 15 selected test methods pass, including 26 QEMU ARM PID1 scenarios and 49 production PHY-wake scenarios. Tests preserve distinct raw values on early refusal, show unread fields on partial reads, preserve the error and finish the bounded heartbeat loop. PHY6a=BE refuses with zero extra reads and zero writes. Sentinel fixture values are synthetic, not device measurements.

• Actual artifact/mutation, BOOTIMG, D08, time32 syscall, text/framebuffer and

  watchdog checks pass. Resolved config differs only in LOCALVERSION. DT memory and hardware policy remain unchanged; chosen initrd end follows its new size. Layout and iteration record retain exact results.

• Linked snapshot at c0015208 remains PID1-only/cached and checks size 260.

  Compared with CHRDET-01, its only two changed instructions load the relocated y2-usb-state resource-name pointer; both old/new strings were checked. All other snapshot instructions and the USB-read/PWRAP-read/request/ack/delay helpers compared are byte-identical. The guarded PHY write remains c0015b90. Hardware-access source hashes match the retained previous layout.

• D08 described RAM remains 24 MiB + 512 KiB. Resident kernel remains

  [0x80008000,0x8029f5b0). Initramfs gzip is 6472 bytes and ends at 0x84001948; decompressor workspace ends at 0x803909e8. Complete LK read-tail and 16 MiB BOOTIMG partition checks pass. No duplicate build or unchanged provenance audit.

• Output retains source snapshot, input lock, ELFs/config/build and test logs,

  focused linked disassembly/comparison and artifact hashes.

Owner test — stop here

Use the established BOOTIMG-only procedure. Attach the USB data cable to the Linux PC before powering on the Y2, and leave it attached throughout this boot. Keep the existing maximum 60 seconds from power-on and manual BOOTIMG restoration boundary. No other partition or persistent calibration is part of this experiment.

Expected: continuing heartbeat, PW:0 /7, CLK:0/15, valid CHRDET and either:

• Guard refuses again: LAST ERR PHY WAKE -19; bottom rows `PRE P:… D:…

  HW:… W:-19/0,PHY68:…,DMA:…,IRQE TX:… RX:… USB:…`. This is a useful result; it exposes the previously hidden startup state.

• Wake succeeds: established WAKE/6A/CTL/TRIM before/after rows. Record this

  result as seen; successful wake alone still does not establish a USB session.

Return two readable full-screen photos from the same boot, near BEAT 10 and near BEAT 50/STOP within the existing time limit, in out/m2-usbguard-01/. Include all four bottom rows, CHR/PW/CLK, LAST ERR, heartbeat/uptime and IRQ count. Report any freeze/reset and exact cable timing if it differed. If stalled, record the last visible stage and elapsed time; do not extend the time limit. No enumeration or ttyACM is expected yet.

Retained fallback: out/m2-chrdet-01/BOOTIMG.img, SHA-256 e511fb89e45326673183f426a4bdd3b6ca708c25bf3e6ceecfc4a67478aa9660. Its connected-start guard refusal is now documented; it is not a connected-wake success fallback. Earlier PHYWAKE-01 remains retained with its recorded evidence.

No physical device operation was performed. #23/#27/#28 remain open; M1 stays complete, M2 exit blocked, M3/audio and Y2PlayerNative deferred.