firmware/docs/building.md

Building your own packages

You need a stock FlashForge update package for your model — this builds from it, it does not replace it. Everything else is Docker.

cp config.env.example config.env     # what to build, and what ships
$EDITOR config.env                   # point it at your stock package
make build                           # the firmware

The package lands in work/out/. make release builds both models into dist/.

Requirements

Docker. That is the whole list — the build image carries openssl, tar, xz, unzip, python3, binutils, squashfs-tools and qemu-user-static, and every target runs inside it. make shell drops you into it. LOCAL=1 make <target> runs on the host instead.

The test targets get the docker socket mounted through, so they can start the replica as a sibling container — and so does make shell, which shares their run flags. A build cannot reach the docker daemon.

The pipeline

fetch-assets.sh  download Mainsail + HelixScreen into vendor/ (see below)
unpack.sh   decrypt the stock .tgz, open the software component
patch.sh    apply the mods to work/software/ and build work/modpayload/
pack.sh     regenerate md5sum.list, tar, encrypt → work/out/<Model>-anvil-<date>.tgz
verify.sh   simulate every check the printer performs, against the built file

make build is all four. Each is idempotent and safe to re-run.

Packages carry only the software component by default. The stock installer skips any component that is absent, so the kernel, the rootfs image and the MCU/board firmware are left untouched — MCU flashing is the riskiest thing in a package and there is no reason to run it for a userspace mod. FULL=1 make <target> carries all four.

One build

There is one package: the forked Klipper with toolchanger support, Mainsail/Moonraker, ssh, and HelixScreen as the UI. bin/common.sh defaults the BUILD_* flags to exactly that, and config.env can override any of them if you want a piece left out.

There used to be a profiles/ directory choosing between builds — five of them at one point (ssh, web, full, helix) climbing one feature at a time, then two (probe, default). The intermediate rungs each cost their own flash-and-verify cycle while the recovery story stayed the same at every one of them (flash the stock package), so they bought caution nobody was spending; the last of them, probe, changed nothing on the printer and only wrote a diagnostic report to the USB stick, which was a bring-up aid rather than something to keep shipping. With one build left, the selection layer went with them.

make build                        # the firmware
make release                      # both models, into dist/
MODEL=Creator5 make build         # just the non-Pro

Two kinds of flag

This distinction is the one to keep straight:

• BUILD_* decides what goes into a package. Read at build time only, defaulted in bin/common.sh, never present on the printer. (BUILD_KLIPPER, BUILD_TOOLCHANGE, BUILD_MAINSAIL, BUILD_MOONRAKER, BUILD_HELIX.)
• MOD_* are runtime switches. They are written into /usr/data/anvil/anvil.conf, which the printer re-reads at every boot, so they can be changed over ssh afterwards and survive a mod update. (MOD_WEB, MOD_CAM, MOD_UI, MOD_WIFI, plus the MOD_CAM_* tunables.) MOD_SSH is the odd one out: it is written to the same file, but nothing on the printer reads it — it is consumed at build time by bin/patch.sh to decide whether to set a root password, and ssh itself comes from the stock /etc/init.d/S50dropbear regardless.

Third-party pieces are downloaded, not vendored

Mainsail and the HelixScreen build for this printer are large binaries, so the repo does not carry them — and never has, so there is nothing in the git history either. versions.env pins each one by version and sha256:

MAINSAIL_VERSION="v2.18.2"
HELIX_VERSION="v0.99.115-creator5"

bin/fetch-assets.sh downloads them into vendor/ (gitignored) and refuses anything whose sha256 does not match the pin. A cached file with the right hash is never re-downloaded, so it is a no-op on every build after the first. bin/build.sh calls it for you; make vendor pre-fetches everything.

To bump a version: edit versions.env — for HelixScreen that means both HELIX_VERSION and HELIX_FILE, which embeds the version in the filename — set the matching sha256 to SKIP, and run make vendor. It downloads the new file and prints its hash for you to paste back over the SKIP. With a stale hash left in place make vendor fails instead of printing anything.

Setting MAINSAIL_ZIP or HELIX_TGZ in config.env points the build at your own local copy. It is still checksummed against versions.env, and on a mismatch fetch-assets.sh overwrites your file with the pinned release — SKIP re-downloads too. To build against your own file, put its sha256 in versions.env as well; only an exact match is left alone.

If the build asks for Mainsail or HelixScreen and the file is not there, it fails. It used to skip silently, which shipped a package with an empty web root and no way to notice.

The root password

ROOT_PW_HASH in config.env is written straight into the shipped shadow file at build time. Leave it empty and the installer picks a random password on the printer instead, and writes it to anvil-password.txt on the USB stick it was flashed from.

The reason it works that way: a package is one file that many people flash, so any password baked into it would be the same on every machine. Generating it on the device is what makes it per-printer, and the stick is the one channel back to the person standing at the machine.

If the stick cannot be written, no password is set — a password nobody can read is no better than no access, and leaving a guessable one behind would be worse than saying so.

bin/patch.sh decides which of the two applies and sets MOD_PW_AUTO in the injected install block; payload/run-append.sh does the on-device half with the printer's own mkpasswd.

Two config files

config.env	The build config: where your stock package and source trees are, which model, the root password hash. Some of it ships.
test.env	The replica config: the factory image, the partition sizes, an optional prebuilt printer image. None of it ships, ever.

Both are gitignored; copy the .example of each. CONFIG_ENV=<path> and TEST_ENV=<path> override the locations.

Layout

The repo has two lanes, and the directory a file sits in says which one it belongs to. Nothing from the test lane can reach a printer.

Ships — everything that ends up inside the .tgz and runs on the machine:

payload/        POSIX sh, busybox ash -- runs ON the printer
  firmwareExe     the wrapper that replaces the stock binary
  start.sh        replaces the stock Klipper launcher (priority, MCU bring-up)
  init.d/         S50wifi, S60web, S65camera, S70klipper, S80ui
  bin/            ff-mcu-bringup.py, wifi-action.sh
  klipper/        extras/ff_*.py and config/ff-*.cfg + printer.base.cfg
  helixscreen/    the printer-database entry that makes it a toolchanger
  anvil.conf      runtime switches, preserved across mod updates
  run-pre.sh      backups, injected at the TOP of the stock run.sh
  run-append.sh   payload install, injected before its exit
assets/         nginx.conf, moonraker.conf

Builds it — host-side, never installed:

bin/            fetch-assets -> unpack -> patch -> pack, plus verify
versions.env    pinned Mainsail / HelixScreen versions + sha256
vendor/         where fetch-assets.sh caches them (gitignored)
config.env      your paths, the root password hash, the model
docker/         Dockerfile.build -- the container every target runs in

Tests it — never ships, and never touched by a build:

test/           run-tests.py, and the shared pytest fixtures
  ffsim/          the host side of the harness, as a python package:
                  config loading, the docker plumbing, gate reporting
  integration/    the suite
    test_chamber.py         the Klipper config gate -- no firmware needed
    test_paths.py           payload paths against the real rootfs
    test_includes.py        the [include ff-*.cfg] block, exact set and order
    test_config_ownership.py  DO-NOT-EDIT banners on the mod-owned configs
    test_gcode.py           gcode/*.gcode against the macros we define
    test_harness.py         static checks on the harness itself
    make-stock-fixture.sh   synthetic stand-in for a stock package
    printer/        the replica itself: binfmt, mount layout, its two
                    Dockerfiles, and the cases that run inside it on the
                    printer's own binaries -- SHELL, because the printer's
                    busybox ash is the only interpreter that matters there
    extract-rootfs.py       pulls the real rootfs out of the stock package
    sim-*.py, printer-exec.py   host-side launchers, via the docker socket
    build-printer-image.sh  bakes a prebuilt replica image
test.env        replica settings only -- factory image, partition sizes
docs/           the documentation

Not everything in there needs the firmware — the config gate needs only python3 and jinja2, and runs on a bare checkout. It briefly had a directory of its own, test/unit, so that a pull request had something to run; with one maintainer who always has the firmware, that was a boundary kept in sync for nobody. run-tests.py extracts the rootfs before it runs pytest, so a single invocation covers as much as the machine allows and reports the rest as gates that did not run.

The line between Python and shell here is not taste. Everything that runs on YOUR machine is Python; everything executed by the printer's own busybox under qemu stays shell, because the fact that it survives that is a large part of what the suite proves. See testing.md for why the host half moved.

Two things keep the boundary from eroding: only payload/ and assets/ are ever copied into a package by patch.sh, and make verify fails if a built package contains any file byte-identical to one in bin/, test/ or docker/.

Rebuilding chelper

klippy/chelper/c_helper.so must be MIPS32r2 / nan2008 / o32 or klippy dies on import — patch.sh refuses to build a package with anything else, and test-install checks the copy that lands on the machine. Debian's cross-compiler cannot produce one; use the Ingenic/K1 toolchain. See the Klipper fork's own notes.

Nothing checks the .so's symbols against the klippy tree shipped beside it. cffi resolves symbols lazily, so a c_helper.so built from older sources than its klippy imports cleanly, passes the ABI check, installs and boots, and then dies at Unhandled exception during connect with a traceback pointing at cffi rather than at the stale build. If you see that on the printer, rebuild the .so before looking anywhere else.