mirror of
https://github.com/Klipper4FlashForge/firmware.git
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Oleksandr ShyshatskyiandClaude Opus 5
99706bb5f7
The Bootlin swap two commits ago (musl.cc -> mips32el) fixed a
reachability problem and kept a correctness one: mips32el is plain
mips32r1, whose musl crt/libc is legacy-NaN by construction and cannot
be made to emit nan2008 output at all -- forcing -mnan=2008 on it fails
to LINK ("mixing -mnan=2008 module with previous -mnan=legacy modules").
So every s6 binary this repo has shipped read e_flags=0x1007, defended
in five separate places as correct on the theory that a supervisor
doing no floating point cannot care about NaN encoding.
True of the arithmetic. False of exec(): docs/how-it-works.md already
documented, for a different binary, that "the Ingenic X2000 kernel
returns ENOEXEC for legacy-NaN MIPS" -- the ABI check happens before a
single instruction of the program's own runs, which means it was never
about what s6 computes. None of the replica gates that "measured s6
working on the printer" ever caught this, because none of them ran on
the printer: qemu-mipsel-static's user-mode emulation does not enforce
the same ABI check a real kernel's binfmt loader does. A build that
passed case-supervisor.sh, case-services.sh, case-moonraker313-s6.sh and
a full release run was still shipping a supervisor that a real X2000
kernel may refuse to start at all.
THE FIX. Bootlin also publishes mips32r5el: MIPS Release 5 has no
legacy-NaN silicon to be compatible with, so its musl crt/libc is
nan2008 by construction, and its default codegen already targets
mips32r2. Verified outside the repo before touching anything: fetched
the tarball, cross-compiled skalibs+s6 with it, every binary read
nan2008/o32/mips32r2, and s6-svscan ran and supervised under
qemu-mipsel-static. Section 5b now applies the same gcc-wrapper
discipline 5c already uses for the Ingenic toolchain -- -EL -mnan=2008
-march=mips32r2 baked into the driver, not left to CFLAGS, with a probe
gate before building anything on top -- because "the toolchain's default
happens to be right" is exactly the kind of assumption this bug was.
mips_abi_gate moved earlier in the file so 5b can use it, and s6 is IN
that gate now rather than exempt from it -- exempt is how this shipped
wrong for as long as it did. The gate itself grew a real relaxation
alongside the real tightening: a static EXEC from this musl toolchain
legitimately carries EF_MIPS_PIC (musl's crt is unconditionally -fPIC;
no combination of -static/-no-pie/-fno-PIC removes it, measured) and so
reads the DYN flag value anyway, which is a property of the toolchain
and not a sign of anything wrong -- so the gate now accepts either
0x70001405 or 0x70001407 for any object, rather than picking one from
the ELF Type.
Also bumped S6_STAMP to include MUSL_TOOLCHAIN_FILE: without that, a
checkout with an already-built work/.s6 from before this commit would
read its own stale legacy-NaN tree as current and never rebuild it.
Full real build: "s6: 14 ELF objects are nan2008/o32/mips32r2 -- good".
case-supervisor.sh green on the replica with the new binaries.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
226 lines
12 KiB
Markdown
226 lines
12 KiB
Markdown
# The Python packages Moonraker and klippy need, cross-built for mipsel
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The second half of phase 6. `tools/python/` builds the interpreter;
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this builds what runs on it. **Now wired into `bin/patch.sh` section 5c,
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step 4** -- see "What is left" at the bottom for what that did and did not
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settle. `build.sh` is the measurement harness, preserved here because it is
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where the findings live, exactly as `tools/supervisor/` is for s6; it is not
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what a release runs any more, and the two have drifted on purpose (patch.sh
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builds offline from `vendor/` and needs no docker, because the build lane has
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no docker socket). `fill-designators.py` is the exception: it is a real build
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input, called by `patch.sh` for greenlet.
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Everything below was run in the printer replica on the real
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`rootfs.squashfs`, not read off a project page.
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`test/integration/printer/case-pyext.sh` is that run, kept.
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## What builds
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18 sdists, 12 mipsel extension modules, from a 56-second clean build in one
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throwaway `debian:bookworm`. (This said 19 for a while; the list below is 18,
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and `versions.env` -- which is now the list that matters -- pins 18.) Every
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`.so` is gated at `e_flags=0x70001407`,
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`nan2008/o32/mips32r2` -- shared objects carry `EF_MIPS_PIC`, so they read
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`…07` where an executable reads `…05`.
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Native: cffi, greenlet, lmdb, markupsafe, streaming-form-data, tornado
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speedups, pillow. Pure: jinja2, distro, inotify-simple, libnacl, dbus-next,
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preprocess-cancellation, pyserial, pyserial-asyncio, pycparser, smart_open,
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setuptools.
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**The list is deliberately not `moonraker-requirements.txt`**, which installs
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every optional component's dependencies. It is the closure of what the
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*enabled* component set imports -- `moonraker.conf`'s sections plus
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`CORE_COMPONENTS` -- plus klippy's. So no apprise, ldap3, paho-mqtt, zeroconf
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or python-periphery. `msgspec` and `uvloop` are skipped on purpose: Moonraker
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guards both with `contextlib.suppress(ImportError)` and falls back to the
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stdlib, measured.
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## The method
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No crossenv. The staged interpreter already carries
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`_sysconfigdata__linux_mipsel-linux-gnu`, so exporting
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`_PYTHON_SYSCONFIGDATA_NAME` at an x86-64 build-python **of the same 3.13.7**
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makes setuptools answer every question for the target. The stage is
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bind-mounted at `/usr/data/anvil` so `INCLUDEPY` resolves unmodified. Plus the
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gcc-wrapper trick from `tools/python/build.sh`, which is what gets
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`-EL -mnan=2008` onto the link lines.
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## What fought back, and what it cost
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* **greenlet was the expected blocker, for an unexpected reason.** The MIPS
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stack-switching assembly was never a problem. greenlet 3.x is C++ and writes
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its `PyTypeObject`s as designated initializers, which gcc 7.2 accepts only
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in declaration order with no gaps:
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sorry, unimplemented: non-trivial designated initializers not supported
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The exact rule was probed rather than assumed: in-order contiguous is fine,
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a *trailing* gap is fine, an *interior* or *leading* gap is refused.
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`fill-designators.py` writes the skipped fields back as explicit zeros,
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taking field order from the target's own headers and refusing to guess when
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a designator is not in them. 55 fields across two files, semantically a
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no-op -- static storage duration, those fields were already zero -- and the
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result switches out and back, in order, on the printer.
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* **pip silently downloaded x86-64 manylinux wheels** for cffi, greenlet and
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tornado on the first run. Three wrong-architecture `.so` files sailed
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straight through the build and only the ABI gate caught them.
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`--no-binary :all:` is mandatory here, not caution.
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* **lmdb chose its cffi backend** and produced a `py3-none-any` wheel with
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`mdb.c` inside -- which is phase 6's recorded trap rebuilt from scratch: on
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the printer that path tries to invoke a compiler that does not exist.
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`LMDB_FORCE_CPYTHON=1` fixes it. Note `LMDB_FORCE_CFFI=0` makes it *worse*:
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the variable is tested for presence, so `"0"` selects cffi.
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* **pillow 10.3.0 cannot be built by any 3.13**, cross or not: its `setup.py`
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does `exec(...)` then reads `locals()["__version__"]`, which PEP 667 broke.
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11.0.0 is the first version that works.
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* **streaming-form-data 1.13.0** (Moonraker's pin) ships pregenerated Cython C
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calling the 4-argument `_PyLong_AsByteArray`, which grew a fifth parameter in
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3.13. 1.19.1 instead, which then wants `smart_open` at module scope.
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## What it proves
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Beyond "it imports", which proves very little on its own:
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* cffi does `cdef` + `dlopen` + call through libm -- klippy's exact ABI-mode
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usage.
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* **cffi dlopens the printer's own `/usr/prog/klipper/klippy/chelper/c_helper.so`,
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resolves `stepcompress_alloc`, `steppersync_alloc` and
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`itersolve_generate_steps`, and calls one.** That is phase 7's central
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question -- whether a Python we built can drive FlashForge's C helper --
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answered yes, and it is the reason the interpreter had to be glibc and not
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musl.
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* lmdb writes and a *second process* reads back.
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* pillow decodes, resizes and re-encodes a PNG: the real thumbnail path.
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* **all 16 Moonraker components import on 3.13**, the list taken from
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`CORE_COMPONENTS` + `moonraker.conf` rather than written down here.
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* zero `/usr/prog` libraries mapped, with every extension imported.
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* Negative control: move the tree aside and every third-party import fails.
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## Size
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13.5MB built, 2.9MB gzipped, 1073 files; 18.2MB on the printer once
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`__pycache__` exists. With the interpreter, about 50MB.
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`setuptools`/`pkg_resources` are 4.9MB of that -- 36% -- and are not needed at
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runtime: measured, with them removed lmdb still loads its CPython extension
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and all 16 components still import. The phase-6 trap was the lmdb *egg*'s cffi
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fallback, and installing lmdb as a wheel removes it. Dropping them is a size
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decision, not a correctness one.
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## Moonraker SERVES on 3.13 -- settled, not assumed
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Importing is not serving, so it was run. `test/integration/printer/case-moonraker313.sh`
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starts Moonraker on the exact command line `payload/etc/s6/moonraker/run`
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execs, only with our interpreter, against the mod's own `assets/moonraker.conf`:
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* bound :7125 in 3s, `/proc/PID/cmdline` confirming our interpreter and our
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entry point
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* `GET /server/info` 200 with **23 components loaded and 0 failed**;
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`/machine/system_info` (a different component, reading this box's /proc)
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reports `cpu: mips`, `python 3.13.7 [GCC 7.2.0]`
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* the **database really works**: POST wrote a namespace, GET read it back, the
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namespace appears beside Moonraker's own, and `data.mdb` is 147456 bytes on
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disk -- through `lmdb/cpython.cpython-313-mipsel-linux-gnu.so`, not the
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compile-at-import cffi fallback
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* alive and still answering **120 seconds later**, zero tracebacks in its log,
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and SIGTERM released the port in 2s
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* **the running process maps 0 libraries under `/usr/prog`**, with
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`LD_LIBRARY_PATH` completely unset -- not merely purged of `/usr/prog`
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* negative controls: nothing on :7125 beforehand, and with `site-packages`
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moved aside it never binds
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What is still unproven is endurance and integration, not capability: no real
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hardware, no live klippy attached (`klippy_connected=False` throughout, so the
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klippy_apis paths loaded but were never exercised), no upload through
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streaming_form_data, no websocket client, and it has not been run through
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`S62moonraker` under s6 on 3.13 -- the entry point was driven directly, on
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purpose, so that a failure would be the interpreter and not an init script.
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## libsodium: built into the prefix, and it costs anvil-env.sh nothing
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`build-libsodium.sh` cross-builds libsodium 1.0.20 with the Ingenic toolchain
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(24s), gated at `0x70001407` nan2008/o32/mips32r2, SONAME `libsodium.so.26`,
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needing only libpthread, libc and the loader. 406KB stripped, into
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`$MODDIR/lib`.
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It does not need a new `LD_LIBRARY_PATH` entry, which is the pleasant part.
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libnacl's third fallback is `__file__[0:__file__.find("lib")+3] +
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"/libsodium.so"`, and `__file__` is
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`$MODDIR/lib/python3.13/site-packages/libnacl/__init__.py`, so it resolves
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`$MODDIR/lib/libsodium.so` **by absolute path** -- measured working with
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`LD_LIBRARY_PATH` unset entirely. Worth writing down that this works because
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the prefix happens to contain the string `lib`; a prefix without it would
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break silently. Adding `$MODDIR/lib` to the path also works and is the
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belt-and-braces option, but it would put our libraries in front of everything
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for every mod process, which is the kind of entry this file's own history
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argues against.
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It computes as well as loads: `sodium_version_string()` is 1.0.20, its
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BLAKE2b-256 matches CPython's own `_blake2` on the same kernel, and
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`libnacl.sign.Signer/Verifier` -- the exact ed25519 pair `authorization.py`
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imports -- signs, verifies and rejects a tampered message. With it,
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`/usr/prog/libsodium/lib` can come off `ANVIL_LIBS`, though only as part of the
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same one-line `FF_PYTHON` switch, since 3.8's libnacl still needs it.
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## What was left before FF_PYTHON could switch
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**Done as of the commit that flips `FF_PYTHON` in `payload/anvil-env.sh`.**
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Capability was settled first -- Moonraker serves, the database works,
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libsodium is ours -- and packaging and integration followed:
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1. ~~**Wire into `bin/patch.sh`.**~~ **Done.** The package build runs inside
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5c against the untrimmed stage, BEFORE the trim, which was the
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recommendation here and is still the only place all three things it needs
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exist at once: the headers `INCLUDEPY` points at, the static C libraries in
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`work/.py-dep` (pillow's zlib, cffi's libffi) and the x86-64 build-python.
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The consequence is that `work/.py313` has **two stamps** -- `.version` for
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the interpreter and `.pkg-version` for the packages -- and a package bump
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rebuilds CPython too, which is the price of not caching a second untrimmed
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tree. libsodium is its own section, 5d, cached separately in
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`work/.sodium`. Every pin is in `versions.env` with a sha256 and
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`bin/fetch-assets.sh` fetches them, so **patch.sh no longer talks to a
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network**: no `get-pip.py`, no PyPI, `pip --no-index` against hashed
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sdists. The build-python gets its pip from `--with-ensurepip=install` out
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of the same pinned CPython tarball. Two build-image packages were needed
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and are in `docker/Dockerfile.build` with the reason beside them:
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`zlib1g-dev` (a build-python without zlib cannot unpack a wheel, or pip
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itself) and `patch` (lmdb's `setup.py` shells out to `/usr/bin/patch`).
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2. ~~**Extend the ABI gate's reach.**~~ **Done**, as described: same rule,
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pointed at the staged payload instead of the build cache -- the
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interpreter, `lib/python3.13` (stdlib *and* site-packages) and libsodium's
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resolved `.so`. Originally not `$MOD_PAYLOAD/bin/s6-*`: s6 was believed
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exempt, reading `e_flags=0x1007` (legacy-NaN) from a plain mips32r1 musl
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toolchain on the theory that a supervisor doing no floating point cannot
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care about NaN encoding. True of the arithmetic, false of exec() -- a
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nan2008-only kernel can refuse a legacy-NaN binary outright, which
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qemu-mipsel-static's user-mode emulation never enforced, so this shipped
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before it was caught. s6 is IN the gate now, built with Bootlin's
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mips32r5el toolchain (nan2008 by construction), same rule as everything
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else in 5b.
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3. ~~**Run it through `S62moonraker` under s6 on 3.13.**~~ **Done.**
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`test/integration/printer/case-moonraker313-s6.sh` drives the real boot
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path -- S40s6's scandir, S62moonraker, readiness gating on `:7125`
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actually listening rather than the process forking, a `kill -9` respawn
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back onto 3.13, and a stop that stays stopped -- and all of it passed on
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the replica.
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4. ~~Then the switch itself.~~ **Done**: `FF_PYTHON` in `anvil-env.sh` and
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`/usr/prog/libsodium/lib` off `ANVIL_LIBS`, in the same commit.
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5. klippy is **not** blocked by packages, and was never part of this switch:
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it keeps running on FlashForge's 3.8.2, started independently by
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`/usr/prog/klipper/start.sh` (see `init.d/S70klipper`), not by
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`FF_PYTHON`. cffi, greenlet, jinja2, markupsafe
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and pyserial all build, and `c_helper.so` binds. `numpy` is the only gap,
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wanted solely by `extras/stepper_resonance_tester.py`, which Klipper loads
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on demand. numpy on 3.13 means numpy >= 2.1 and a Meson cross-file, and
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that genuinely is a multi-day rabbit hole. It costs input-shaper
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calibration, not printing.
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Unverified: no real hardware, replica only; nothing has run under sustained
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load; and the greenlet designator patch is a no-op by argument plus a working
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switch test, not by upstream blessing.
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