Capture Y2 CDC ACM logs

Current integrated candidate: M2-BASELINE-03 handoff. Baseline captures default to 180 seconds; the owner power-on limit is 300 seconds. The older USBACM-04 procedure below retains its historical 60-second boundary. Use its single combined host capture for delayed open, paused reads and one physical cable cycle. It identifies the actual USB tty on each enumeration; never infer the Y2 from ttyACM numbering alone. Run on the real host, outside any private-device sandbox, with permission to open both enumerations.

For ordinary USBACM-04 logging use usb_log_capture.py --output NEW_DIRECTORY. For a still-running USBACM-03 image add --build M2-USBACM-03; the default header now identifies USBACM-04. All older commands below require that explicit option when using the current tool. Keep each capture in a new directory.

The USBACM-03 success is already recorded and pushed: 11754 bytes, kernel sequence 0–77, BEAT 1–43 and normal 45-second exit 0. Current session host metadata identifies port 5-2, ttyACM0, 0525:a4a7 and the USBACM-03 manufacturer; host visibility succeeds, but luca lacks tty access (root:uucp 0660, no ACL, no passwordless sudo). Host permission is a separate prerequisite from visibility.

Historical USBACM-03 capture procedure

For M2-USBACM-03, Linux host, standard Python 3 only. Run from the repository before powering on the test image:

python3 tools/observation/usb_log_capture.py --output out/m2-usbacm-03/capture-01

Run on the real host with its /dev and /sys. A sandbox with private device nodes can report no matching device even when the host enumerates the Y2. USBACM-03 has now enumerated successfully; capture-01 failed on sandbox visibility and capture-02 failed on tty permissions. On this host the port is root:uucp 0660 and luca lacks access. For the next trial, the owner can run this one capture in their terminal, supplying the local sudo password there (not in chat):

sudo python3 tools/observation/usb_log_capture.py --output out/m2-usbacm-03/capture-03

This does not change groups, udev rules or global device permissions. It will create root-owned capture files. Keep prior capture directories intact.

The new output directory must not already exist. The tool waits up to 90s for one USB-backed ttyACM device with g_serial 0525:a4a7 and CDC ACM class/subclass. This host wait does not extend the Y2's 60s-from-power-on observation limit. It refuses multiple matches; optionally specify --device /dev/ttyACM0 after identifying the correct port. Selection still validates USB identity. No device is flashed, reset, mounted or exported by this tool.

Boot the Y2 without the USB cable. Wait for ATTACH USB CABLE NOW, then attach the data cable to this PC promptly. Leave it attached during this first trial. If the prompt never appears, return a readable full-screen photo, including POLL/PW/V, WACS and G rows if displayed. A failed live PMIC poll can replace the prompt before it is noticed. Do not try connected-start recovery. The old connected-start PHY6a=BE guard remains.

If enumeration works, the tool opens raw 115200/8N1 without flow control, asserts ACM DTR, sends only LOG1\n, and collects for at most 45s/1MiB. The baud setting is ACM line coding, not a UART wiring requirement. It accepts no shell commands. Capture may end on the candidate's 50s active-window disconnect; preserve the usual manual BOOTIMG restoration by 60s from power-on. Do not reconnect during this first trial: controller reconnect is not implemented or qualified yet.

The host user must already have permission to open the tty. If it fails, retain failure.json; no host group, service or udev rule is changed automatically. Do not substitute an unrelated tty or change permissions globally.

Return the whole capture directory:

• capture.json: USB parent/path, descriptors, identity, start time, byte count,

  SHA-256, stop reason, LOG1 header check and exit code.

• raw.bin: exact returned bytes, including native /dev/kmsg records and

  PID1 startup/heartbeat status. The first line should identify M2-USBACM-03.

• chunks.jsonl: monotonic receive timing and byte offsets.
• failure.json, if enumeration/identity/open failed.

A valid header and bytes are transport evidence, not automatic M2 qualification. The report always leaves hardware_qualified=false; an evidence review must establish early real kernel messages, increasing PID1 beats, timing, stability and any GAP/ERR markers. If enumeration fails, the stage/error/IRQ/DEVCTL screen and USB host diagnostics locate the failed part of the same combined attempt. Keep one readable full-screen photo near BEAT 10 and another late in that same boot, within 60s, if practical; note power-on and cable-attachment timing.

The host tool opens only a verified CDC ACM port and writes one log request plus standard line-control operations. It provides log inspection, not ADB or an interactive device shell. Its automated tests use PTYs/fake sysfs exclusively.