BFE Engineering
c756622c96
The repo's documentation framed it as a support repo for one product (WardenOS). Since going public the real audience is anyone with a Luckfox Pico 86 Panel: a maintained 6.18 kernel, an off-device development loop, and a device simulator that exist nowhere else for this board. Reframe the README and top-level docs board-first, with WardenOS documented as the downstream consumer it is (ADR-0008). Also an editorial pass over the whole doc set: - every H1/H2 is now a short title, not a sentence (ADRs, qemu/, patches/, drivers/, architecture, NPU feasibility, config-lint, payload); workflow flowchart titles fixed at the source in tools/flowgen.py and regenerated with fresh bench numbers - README Quick Start commands verified against the scripts; requirements corrected (curl, bare python, gcc >= 14) and the MC/DC gate added as a step (run green locally on gcc 14.2) - dropped the 'needs python (not python3)' vendor dig: build-kernel.sh inherited the same requirement (filed #10 to remove it) - glossed MC/DC and HPMCU on first use; marked the tests/uboot-ab reference as flare-edge; deduplicated the three-simulator list into the root README table
100 lines
5.3 KiB
Markdown
100 lines
5.3 KiB
Markdown
# The Device Simulator
|
|
|
|
A QEMU virtual machine that boots the real forward-ported kernel (`build/` +
|
|
`patches/`) and real userspace, so the 86 Panel — init, daemons, networking,
|
|
OTA, watchdog, display — can be developed and tested with no board attached.
|
|
It is the third simulator in the stack (the root README's table has the
|
|
three-way split), deliberately not named "sim": where `sim/` models
|
|
registers, this runs the whole machine above the kernel entry point on real
|
|
binaries — bring your own, or drop prebuilt payloads in `payload/`.
|
|
|
|
Decision record: `docs/decisions/0006-qemu-device-sim.md`.
|
|
|
|
## The Boundary
|
|
|
|
There is no RV1106 machine model in QEMU and everything below the kernel is
|
|
closed rkbin blobs plus mask ROM, so the VM **enters at `-kernel zImage`** on
|
|
`-M virt,highmem=off` (single Cortex-A7, 256M — the RV1106G3's shape).
|
|
|
|
| Emulated / substituted | Not emulated (stays bench / `sim/` territory) |
|
|
|---|---|
|
|
| Kernel boot, init ordering, switch_root | BootROM, idblock/DDR-init, SPL, U-Boot |
|
|
| A/B *outcome* (`warden.slot=` cmdline) | Real BCB A/B selection, bootcount auto-revert |
|
|
| Storage: virtio-blk with the device's exact `blkdevparts=` layout + `/dev/block/by-name/` contract | eMMC controller itself |
|
|
| Network: virtio-net (slirp, hostfwd 22/80/28443) | GMAC, AIC8800 wifi, usb0 gadget |
|
|
| Display: virtio-gpu 720x720 via fbdev emulation | VOP/RGB666 pipeline, CH32V003 panel init, RGA blits |
|
|
| Touch: virtio-tablet (QMP `input-send-event`) | GT911 on I2C3 |
|
|
| Watchdog: i6300esb (PCI), `-action watchdog=reset` | DW watchdog @0xff5a0000, HPMCU supervisor |
|
|
| RS485: pci-serial chardev bridged to `sim/`'s `ModbusSlave` | Real UART4 timing/electrical behavior |
|
|
| RTC: PL031 (`--rtc` reproduces the no-RTC 2021-clock incident class) | The unpopulated backup-cell reality |
|
|
|
|
**"Boots/works under emulation" is never evidence of "works on silicon."**
|
|
The VM narrows which claims need a panel; on-device claims still need
|
|
on-device evidence. Conversely, the VM is the first environment that runs
|
|
production binaries on a non-RV1106 memory map — it found flare-edge #106
|
|
(fatal SIGBUS in flared's HPMCU probe) and #107 (Y2038 time_t truncation)
|
|
on its first two boots of real userspace.
|
|
|
|
Documented guest deviations from production, set by stage-2 init:
|
|
`WARDEN_FLARE_INSECURE=1` (the desk mock portal is plain HTTP) and
|
|
`WARDEN_HPMCU=0` (no mailbox SRAM on virt; flared >= flare-edge#106 fix
|
|
required, or the daemon dies of SIGBUS).
|
|
|
|
## Quick Start
|
|
|
|
```sh
|
|
# 1. kernel: canonical build boots the VM as-is; the fragment variant adds
|
|
# the scenario devices (PCI serial, watchdog, WireGuard, virtio-gpu/input)
|
|
WORK=$HOME/kbuild-out CROSS_COMPILE=arm-linux-gnueabihf- \
|
|
WARDEN_KCONFIG_FRAGMENT=qemu/configs/virt.fragment bash build/build-kernel.sh
|
|
|
|
# 2. initramfs (sha256-pinned static busybox + qemu/rootfs/) and A/B disk
|
|
bash qemu/mkinitramfs.sh
|
|
bash qemu/mkimage.sh # options: --portal-url --state K=V --fw-version
|
|
|
|
# 3. run (see run.sh header for all flags)
|
|
bash qemu/run.sh --kernel $HOME/kbuild-out/linux-6.18.46/arch/arm/boot/zImage --shell
|
|
```
|
|
|
|
Payload: drop static musl armv7 binaries into `qemu/payload/` (see its
|
|
README) — `warden-flared`, `warden-modbus`, and `warden-ui` (the LVGL
|
|
fbdev+evdev build from flare-edge `tools/build-ui-vm.sh`) are started by
|
|
stage-2 init when present.
|
|
|
|
## Scenarios
|
|
|
|
- `boot-smoke.sh <zImage>` — sentinel-asserting boot; runs in CI inside the
|
|
kernel-build job.
|
|
- `portal-scenario.sh <zImage>` (needs `FLARE_EDGE=<checkout>`) — the real
|
|
flared in the VM against the desk mock portal: authenticated check-in,
|
|
firmware desired-state pull, and download of a real signed tier-1 `.wfw`
|
|
offer. Verify/stage/APPLYING run as a dry run (no `WARDEN_FW_ALLOW_APPLY`);
|
|
flipping it on inside the VM is the documented stretch — apply writes
|
|
`/dev/block/by-name/rootfs_b` inside disk.img, then `--slot _b` boots it.
|
|
- `ui-shot.sh <zImage>` — display+touch: boots headless with virtio-gpu,
|
|
QMP-screendumps the 720x720 UI, taps the Metrics tab via `input-send-event`
|
|
(a 200 ms hold — an instantaneous press+release lands inside one LVGL poll
|
|
and never clicks), and asserts the frame changed. `qmp.py` is the tiny QMP
|
|
client.
|
|
- Watchdog: `run.sh --watchdog`, arm `/dev/watchdog` in the guest, don't pet —
|
|
the VM resets ~30 s later (verified). Do NOT combine with a flared payload
|
|
expecting survival: flared pets only while the UI heartbeat is fresh.
|
|
|
|
## Gotchas
|
|
|
|
- AF_UNIX socket paths cap at ~108 chars — keep `--rs485`/`--qmp` paths short.
|
|
- A serial port that is closed discards incoming bytes: hold ONE fd open
|
|
across write and read when scripting the guest side of the RS485 bridge.
|
|
- `highmem=off` and `-global virtio-mmio.force-legacy=false` are load-bearing
|
|
(32-bit ECAM reach; virtio-1-only gpu/input) — both live ONLY in run.sh,
|
|
which every script (boot smoke included) delegates to.
|
|
- Never pass `earlyprintk`: DEBUG_UART_PHYS is the RV1106's 0xff4c0000.
|
|
|
|
## Requirements
|
|
|
|
`qemu-system-arm` (Debian 13 ships QEMU 10), `curl`, `cpio`, `mkfs.ext4`,
|
|
`gcc-arm-linux-gnueabihf` (kernel build), `python3` (+`cryptography` for the
|
|
portal scenario's `.wfw` signing). CI: the hosted `qemu-tools` job builds the
|
|
tooling; the boot smoke runs inside the (also hosted, dispatch-only)
|
|
`kernel-build` job, which apt-installs its own toolchain and qemu (ADR-0007).
|