B14 — Cage + SDL2 modem UI (2026-10-04/05) — USERSPACE VALIDATED

Changes only in Alpine on p27 (no kernel/DTB/cache/GPT/firmware change). Running kernel 7.2.7-aurora-b12 (cache B12R).

1. SDL2

Alpine 3.24: native sdl2 2.32.10-r0 (not sdl2-compat). Compiled video drivers: x11 wayland KMSDRM offscreen dummy evdev; under Cage SDL_GetCurrentVideoDriver() = wayland (aurora-ui refuses to run on anything else). No Xwayland binary on the system.
Pitfalls found: (a) SDL2/Wayland has no shm framebuffer — every window path goes through EGL; (b) without wayland-libs-egl (libwayland-egl.so.1, dlopened) SDL2 segfaults in Wayland_CreateWindow (SDL_waylandwindow.c:2055, NULL wl_egl_window_create); (c) Mesa needs its libgallium/LLVM files (restored in B13W). With LIBGL_ALWAYS_SOFTWARE=1 the renderer is SDL opengl on Mesa llvmpipe via EGL/wl_shm (libgallium); the lavapipe Vulkan ICD (mesa-vulkan-swrast, installed while debugging) is not used (UI works with VK_ICD_FILENAMES=/nonexistent, no lvp mapping) — removal can be tested separately.
No SDL_ttf: 8x16 cp437 bitmap font extracted from Linux lib/fonts/font_8x16.c (GPL-2.0).

2–5. Application

b14/src/aurora-ui.c (~360 lines C, 75 KB binary, -Wall -Wextra clean), built on the board (apk add build-base sdl2-dev), installed /usr/local/bin/aurora-ui. Software-drawn 128x128 ARGB → streaming texture, redraw 1/s (+ on events), worker thread for slow sources. Layout (8 rows x 16 cols, 4 colours + grey):

BEELINE      LTE      operator / RAT                (mmcli every 5 s, timeout 3 s, only while ModemManager runs)
▂▄▆█▒ 70%             signal quality
10.82.242.155         wwan0 IPv4                    (/run/aurora-modem/ipcfg, every 2 s)
WiFi 1 cl             AP up + stations              (iw info + station dump every 5 s)
↓73B     ↑73B         throughput                    (1 s; wwan0 counters are always 0 on bam-dmux → wlan0 LAN counters)
BAT 4.13V   HOLD      VADC VBAT + supervisor state  (B10 /sys/kernel/debug/pm8916_lbc/state, 1 s) — no SOC (no fuel gauge)
PMIC 36°C    NAT      pm8916-thermal + default route
02:02     ONLINE      clock (TZ=MSK-3 from /etc/aurora/aurora-ui.conf) + overall

Before START OK the top rows show MODEM STARTING + the controller state; FAIL → MODEM FAIL. Missing sources render --. Finding: pm8916-bms-vm power_supply reports 4.41 V / "Over voltage" while the validated VADC says 4.19 V → the UI uses VADC only.

6–7. Launcher + wayvnc

b14/run/ui-up.sh [--stop-gui] (refuses if Xorg/Cage/Sway hold the panel; one instance; Pixman/seatd env; waits for first frame), ui-stop.sh, ui-status.sh → /usr/local/lib/b14/run. Process lookup via /proc/PID/exe (the OpenRC script has the same comm name). wayvnc (b13/run/wayvnc-up.sh) on Cage+aurora-ui: same output SPI-1, 172.16.42.1:5900 only (IPv6 listeners 0), TLS+password, VNC pointer/keys do not disturb the app.

8. Test (manual start: X11 stop → Cage → aurora-ui → wayvnc)

Startup: 0.9–2.2 s to first frame (aurora-ui first frame 1.1–1.5 s after exec).
Soak 15 min (soak.log) + control 5 min (soak2.log): aurora-ui RSS 108–114 MB (PSS 95 MB; private dirty ~34 MB, ~43 MB clean mesa/LLVM file pages), Cage 47.6–48.2 MB, both flat; CPU aurora-ui 1.5–1.6 %, Cage 0.16–0.22 %; MemAvailable ~269–271 MB stable. modem BEARER_CONNECTED + LTE ping ok every minute; phone client: NAT forward counters grew, UI showed WiFi 1 cl and live ↓/↑; charger CHARGING → HOLD shown; PMIC 36–49 °C; NCM ping from 480s 919/920 over the soak; eMMC writes outside p27 = 0.
Kernel log: 65 cma: __cma_alloc_frozen: reserved: alloc failed, req-size: 8 pages, ret: -16 between uptime 3289–4892 s. Root cause analysis: the 32 MiB CMA area was filled by movable page cache (after the apk/gdb installs: CmaFree 112 kB) and page migration returned EBUSY; the bitmap had 8000 free pages. Not the UI: 0 failures without UI under LTE load, and after drop_caches (CmaFree 30.6 MB) 0 failures in the 5-min control soak with UI + wayvnc running. Allocations fell back (no traffic impact: ping/NAT fine). Follow-up candidate (separate): watch CMA after large apk operations / consider cma= or vm tuning.
Other kernel messages: only the known boot-time ones (wcnss.mdt at 1.4 s before /firmware, regulatory.db).

9. X11 regression — PASS

ui-stop → VT tty1 → aurora-x start fbdev → X-START OK 128x128, twm+xterm, x11vnc 172.16.42.1:5900 (IPv4 only), frame OK. UI restored afterwards.

PASS matrix

Cage starts ✔ · SDL2 uses Wayland ✔ · 128x128 physical UI correct ✔ (operator) · live LTE ✔ · Wi-Fi ✔ · traffic ✔ (after fix, operator) · battery/charger ✔ · clock ✔ · wayvnc same output ✔ · LTE/Wi-Fi/router/NCM/charger unaffected ✔ · no kernel errors caused by B14 ✔ (CMA warnings explained above) · no writes outside p27 ✔ · X11 regression ✔

B14 Cage + SDL2 modem UI: USERSPACE VALIDATED

10–11. OpenRC autostart (prepared, NOT enabled)

/etc/init.d/aurora-ui installed on p27 (source b14/run/aurora-ui.openrc), in no runlevel. Activation patch (separate GO):

rc-update add aurora-ui default

Order: need aurora-display; after aurora-ncm aurora-ro — it does not wait for the modem (UI shows MODEM STARTING), starts ui-up in the background so boot never blocks on the GUI; fbcon/getty on tty1 stay as fallback behind Cage; rc-service aurora-ui stop returns the console.

p27 footprint

New packages: sdl2, wayland-libs-egl, mesa-vulkan-swrast (unused), build-base + sdl2-dev (+deps, build only), gdb/musl-dbg/sdl2-dbg (debug). p27 now 1.0 GB used of 2.4 GB. Build/debug packages can be removed with apk del build-base sdl2-dev gdb musl-dbg sdl2-dbg.

Autostart (2026-10-05, GO)

rc-update add aurora-ui default on p27 (default runlevel: aurora-display, aurora-ui, aurora-modem, aurora-wifi, aurora-router, aurora-bootok).
cold1 (normal power-on, no RESET; logs/b14/cold1/): stage0 fsck clean + switch_root at 4.3 s, BOOT OK 6.6 s, UI UP at 9.47 s uptime (Cage + aurora-ui, first frame 1.04 s after exec, SDL wayland/opengl), modem START OK 81.6 s, AP 85.5 s, aurora-router autostart: ROUTER UP OK 88.1 s (first boot with the router in the runlevel), all default services started, CMA failures 0, eMMC writes only p27. Screenshot after boot: BEELINE LTE 60 %, 10.87.61.183, WiFi 0 cl, BAT 4.18 V CHG, PMIC 42 °C, NAT, ONLINE.
Undo: rc-update del aurora-ui default (console/getty on tty1 returns on the next boot) or rc-service aurora-ui stop for this boot.

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