BFE EngineeringandClaude Fable 5
13b7d063a2
Phase 4+5 of the device sim: - Display + touch verified end-to-end: virtio-gpu at 720x720 (fbdev emulation) renders the real WardenOS dashboard from the static LVGL fbdev+evdev UI build (flare-edge qemu-vm-support tools/build-ui-vm.sh); QMP input-send-event taps the Metrics tab and qemu/tests/ui-shot.sh asserts the repaint from screendumps. Two load-bearing QEMU flags found and documented: -global virtio-mmio.force-legacy=false (gpu/input are VERSION_1-only) and the 200ms press hold (an instantaneous press+release lands inside one LVGL indev poll and never clicks). - qemu/tests/qmp.py: minimal QMP client (screendump, tap, quit). - stage-2 init starts warden-ui when present and fb0 exists. - docs/decisions/0006-qemu-device-sim.md: virt-not-custom-board, the enters-at-kernel boundary, fragment policy, naming, consequences. - docs/architecture.md: new section 7 (device emulation), order-of-work item 7; modbus cross-reference to the bridge. - qemu/README.md: emulated-vs-not table, scenarios, gotchas, host/runner requirements. docs/ci-cd.md: runner needs one-time qemu-system-arm install (fail-closed smoke until then, [maintainer]-gated). Repo README updated. Final sweep on this commit: shellcheck clean, bridge 7/7 tests, boot smoke PASS, portal scenario PASS (check-in + fw pull + signed .wfw download), ui-shot PASS (touch navigates to Metrics) — all under the final flags. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018HUayid7W5w7jBdb9Rrj1K
3.4 KiB
ADR 0006 — QEMU device sim: generic -M virt, entered at the kernel
Status: Accepted (2026-08-29).
Context
The two existing simulators cannot test the device: lvglsim (flare-edge)
is an SDL rendering harness, and sim/ models registers behind driver seams.
Init ordering, the daemons as real processes, networking/enrollment against
FLARE, OTA, and the watchdog were testable only on a bench panel — flare-edge's
fault suite marks five scenarios "HIL, human prompts", its Playwright e2e needs
a live panel on the LAN, and its OTA desk test stops at "reached APPLYING".
Two ways to emulate the panel were considered:
- A custom RV1106 QEMU board model. Nothing exists upstream or in the
community, so this means writing VOP/CRU/GRF/eMMC/HPMCU device models from
scratch and maintaining them against QEMU — months of work that duplicates
what
sim/already models in Rust. It still could not run the boot chain: BootROM is mask ROM and the DDR-init/idblock stages are closed rkbin blobs. - The generic
-M virtmachine, entering at-kernel zImage. The forward-ported 6.18.46 config is multi_v7-derived and already carriesARCH_VIRTplus the full virtio set — the canonical RV1106 zImage boots virt unmodified (verified 2026-08-29). Peripherals become virtio substitutes; SoC-block behavior stays insim/, bridged in (the RS485 chardev bridge) rather than re-modeled.
Decision
Option 2. qemu/ holds the harness: qemu-system-arm -M virt,highmem=off -cpu cortex-a7 -smp 1 -m 256M (the RV1106G3's shape), one canonical kernel
image plus an optional additive config fragment (qemu/configs/virt.fragment
via the WARDEN_KCONFIG_FRAGMENT hook — PCI/pci-serial/i6300esb/WireGuard/
virtio-gpu/virtio-input; the RV1106 build is byte-identical with the variable
unset). The VM carries the device's real 12-partition blkdevparts= A/B
layout on a virtio disk and populates the /dev/block/by-name/ contract.
The name is qemu/, not any variant of "sim" — the wikis already warn that
"sim" is two different things.
Notable mechanics: highmem=off because the non-LPAE 32-bit kernel cannot
reach virt's default 40-bit PCIe ECAM; -global virtio-mmio.force-legacy=false
because virtio-gpu/input are VERSION_1-only devices.
Consequences
- Everything below the kernel is out of scope: BootROM, idblock, U-Boot,
the real BCB-driven A/B selection and bootcount auto-revert. The initramfs
warden.slot=switch emulates U-Boot's choice, not the mechanism. The untested A/B rollback chain stays bench territory. - Display, input, network, and storage are substitutes (virtio), not models. "Boots/works under emulation" is never evidence of "works on silicon"; the VM narrows which claims need a panel.
- The VM is the first environment that runs production userspace binaries on a non-RV1106 physical memory map, which makes it a canary for baked-in hardware assumptions (it immediately found flare-edge #106, a fatal SIGBUS in flared's HPMCU probe, and #107, a Y2038 time_t truncation in the UI).
- The guest deliberately deviates from production in documented ways
(
WARDEN_FLARE_INSECURE=1for the desk mock portal,WARDEN_HPMCU=0); qemu/README.md carries the emulated-vs-not table. - The kernel-build CI job gains a fail-closed qemu boot smoke; hosted runners build (but cannot boot) the initramfs and disk image.