Controlled first Linux modeset after stage-1 preservation

This trial separates the idle Linux kernel, the first Linux logo owner, and Sway on the current exact-mode preservation image. It is a serial-initiated warm boot on the existing card, not the second-card or power-on procedure.

Image and setup

The image remains the corrected initial-scene candidate from source 12c1b0e, whose code was integrated in 61dcc90. Its full image hash and derivation are in initial-scene build provenance. The running system is /nix/store/24h4sb1msncgbasnwl3ckdlxqf9v2g6r-nixos-system-nixos-26.11.20260919.20b1ddd. No source changed, no image was flashed, and no home state was restored.

Preparation temporarily adds systemd.mask=shell.service systemd.mask=k230-drm-splash.service to the boot arguments. Idle boot capture and idle inspection establish:

• The runtime splash flag is present and /dev/fb0 is absent.
• Both display services are inactive; seatd and firewall are active.
• The DRM debugfs client table contains its header and no clients.
• The kernel logs stage 1 splash: leaving fbdev unset, with no panel prepare or VO/DSI first-enable message yet.
• The idle physical photograph shows the retained K230 logo at the serial prompt.

This supplies the display-behavior evidence for task 4.3; its specified second-card prerequisite is still outstanding, so that task remains open.

Why the test uses the immutable logo owner

The installed modetest -h output in idle-inspection.txt offers built-in -F patterns and a writeback output file, but no input image. It cannot scan out a supplied copy of the U-Boot logo. The corrected same-image procedure uses the existing unchanged nix/drm-splash/drm-splash.c: read_asset() validates the immutable 2,799,104-byte B,G,R,X asset; fill_buffer() converts it to RG16; primary-plane format discovery checks support; and the first drmModeSetCrtc() displays that buffer. The unit’s immutable executable is /nix/store/qkvxyd8cajqsz2ablbngzxnzsn4a62cn-k230-drm-splash-riscv64-unknown-linux-gnu-0.1/bin/k230-drm-splash.

The capture script copies the built owner and shell units to alternate names under /run/systemd/system/. This allows deliberate startup while leaving the original command-line masks in place. It starts first-modeset-owner, then signals it to drop master and starts first-modeset-shell. No persistent unit override is installed.

First owner and successor

The 65-second physical recording starts four seconds before the first owner command. The camera audit records the visible transitions and limits. The Sway inspection includes the owner journal: framebuffer 49, connector 48, CRTC 46, RG16; master dropped while retaining that buffer; successor replacement; successful owner exit. It also records Sway’s initial scene seed and removal at replacement commit sequence 7. The native screenshot is a separate compositor-layout aid.

The completed audit reviews every captured frame from 2–16 seconds around the first owner start (420 frames at 30 fps): the logo remains visible in all of them. All 18 frames from 22.45–23.05 seconds cover the shell transition; the last logo-only frame is approximately 22.82 seconds and the first shell bar approximately 22.85 seconds. The observed dark interval is zero captured frames. This satisfies task 4.4’s filmed first-modeset check without triggering its dark-interval fallback; it does not rule out a sub-frame interruption.

owner-inspection.txt contains only the submitted command: its console capture window ended before the response. It is not evidence that those queries returned. The later journal captures provide the missing output. Previous-boot kernel journal identifies controlled boot 581861b66ba74a00ad7d227226e3e99b, matching idle-boot.txt, and records first VO preservation, the panel’s one-shot prepare skip, and first DSI preservation at the manual owner start. No full prepare or PHY timeout line appears in that filtered kernel journal. This is software-path evidence, not an electrical measurement of DCS traffic.

Recovery

The boot-argument restoration restores and compares the original file before the display experiment. Its SHA-256 is 90d0b406f88fe6cba2b175569f2a4402c5fe46e4e5db9549cb50cf7eb24a703e. Recovery boot, inspection, and physical shell photograph record normal automatic startup again: no mask arguments, original units loaded, runtime test units gone, shell/seatd/firewall active, owner replacement and Sway seed/removal logged. The logo remains the immutable image asset.

This trial does not establish battery-only operation, real-finger input, calibrated motion/geometry, or task 5.4’s complete power-on continuity.