mirror of
https://github.com/openglow-org/forgefirm.git
synced 2026-09-27 16:51:12 -07:00
docs: present-state build and update docs; fix the ring-size arithmetic
- kas/README.md: the real-time rationale rests on the feeder's bounded queue depth, not ring size; the ring is 16 MiB (~84 s at 200 kHz, ~28 min at the 10 kHz cloud tick), a capacity for cloud-mode preload. - BUILD.md, kas config, release checklist, cold-build workflow: only forgefirm and meta-openglow (branch scarthgap) are cloned as siblings; every ForgeFIRM source repo is fetched by pinned SRCREV. - UPDATE-SYSTEM.md reads as the present-state design: the cloud-mode compatibility baseline is the cloud client's configured firmware version, not release metadata; decisions and open items listed plainly. - README.md states what GRBL mode still needs the Glowforge service for (camera-referenced homing) and what runs without it. - BRINGUP.md: generic build-host and fwup-lab references, the retained reproductions of the no-fire drill, the System tab. - LIGHTBURN.md: the arm-window timeouts are machine settings. - forgefirm-image.bb describes forgectrl as the machine-services daemon and points at the right backlog entry. - American spelling throughout.
This commit is contained in:
ScottW514
+24
-19
@@ -29,15 +29,15 @@ openglow-forgefirm/
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│ ├── build/ ← bitbake output incl. images (gitignored)
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│ ├── downloads/ sstate-cache/ ← caches (gitignored)
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│ └── .gitignore
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├── meta-openglow/ ← Glowforge BSP layers (local sibling, under migration)
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└── kernel-module-glowforge/ ← glowforge.ko sources (pulled by recipe SRC_URI)
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└── meta-openglow/ ← Glowforge BSP layers (local sibling checkout)
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```
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`meta-openglow` is referenced as a **local sibling** (`../meta-openglow`) while
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we migrate it to Scarthgap, so its in-place edits are what gets built. Once that
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migration is committed/pushed, flip it to a kas-cloned + pinned repo (commented
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block in `forgefirm-glowforge.yml`) and the forgefirm repo becomes fully
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self-contained.
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`meta-openglow` is referenced as a **local sibling** (`../meta-openglow`), so
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its in-place edits are what gets built. The commented pinned-remote block in
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`forgefirm-glowforge.yml` makes the forgefirm repo fully self-contained when
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flipped on. The source repos the recipes build (`kernel-module-glowforge`,
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`grblHAL-glowforge`, `forgectrl`, `python3-gfhardware`, `Glowforge-Utilities`)
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are fetched by pinned `SRCREV` and are not needed as local checkouts.
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## Prerequisites
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@@ -122,7 +122,7 @@ config move in the right order. The sequence, with current status:
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All recipes fetch their pinned revision from GitHub, so an image build is
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reproducible from the repos alone. For fast iteration on a source repo, bump
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its pin per iteration, or add a **local, untracked** `externalsrc` bbappend
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pointing at the sibling checkout — never commit one, or released images stop
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pointing at a working checkout — never commit one, or released images stop
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matching the pins.
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## Scarthgap migration backlog
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@@ -158,8 +158,8 @@ Scarthgap, but the legacy (Dunfell/Gatesgarth) layers won't build clean until:
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- **`glowforge.ko`**: ported across many 6.12 API changes
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(`tasklet_hrtimer`→soft hrtimer, `timer_setup`, LED-trigger API,
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`pwm_get`, `spi_delay`/`controller`, `filelock.h`, void `.remove`,
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1-arg i2c probe). Compiles + links, 0 undefined symbols. Built from the
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local sibling via an `externalsrc` bbappend during migration.
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1-arg i2c probe). Compiles + links, 0 undefined symbols; the recipe
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fetches the module by pinned `SRCREV`.
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- **DT**: `glowforge,cnc/thermal/pic/head` re-added with `pwms`/`pwm-names`
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phandles; `glowforge.dtb` compiles with all motion nodes.
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Motion polish: PWM prescaler (factory 1001) is **obsolete** — 6.12
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@@ -173,7 +173,7 @@ Scarthgap, but the legacy (Dunfell/Gatesgarth) layers won't build clean until:
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- **Camera — DONE and hardware-validated.** The factory
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`ov5648_mipi.c` (NXP's removed `v4l2_int_device`/`mxc_v4l2_capture`) is
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replaced by the mainline `ovti,ov5648` subdev + imx6 `imx-media` (IPU CSI)
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+ `imx6-mipi-csi2` receiver. The factory CAM_SEL MIPI switch is modelled
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+ `imx6-mipi-csi2` receiver. The factory CAM_SEL MIPI switch is modeled
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with the mainline `video-mux` (gpio-mux on `gpio7 10`): both sensors →
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video-mux → `mipi_csi` → IPU CSI. Sensor `xvclk` is the board's 24 MHz
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fixed oscillator (matching the factory DTB); avdd/dovdd/dvdd rails are in
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@@ -202,14 +202,19 @@ Scarthgap, but the legacy (Dunfell/Gatesgarth) layers won't build clean until:
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5. **Real-time strategy — decided.** The kernel runs
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`CONFIG_PREEMPT=y` (factory behavior; `imx_v6_v7_defconfig` alone gives only
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`PREEMPT_VOLUNTARY`). **PREEMPT_RT is not selectable on arm32 6.12** (no
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`ARCH_SUPPORTS_RT`) and is **not needed for the pulse feeder**: the SDMA
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ring is 128 MiB draining at 1 byte per EPIT tick — ≤200–400 KB/s even at
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the 200 kHz ceiling — so a full ring holds **~5–11 minutes** of stream and
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a modest 1 MiB of queued data already rides out ~3–5 s of scheduling
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latency, orders of magnitude beyond anything PREEMPT exhibits. Deep
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buffering + `SCHED_FIFO` for the feeder is the design; revisit RT only if
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the underrun bench ever contradicts this arithmetic. (Bench: 5 s of
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continuous feed at a 1 s buffer depth, zero underruns.)
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`ARCH_SUPPORTS_RT`) and is **not needed for the pulse feeder**. The
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argument is about queue depth, not ring size: the ring drains at 1 byte
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per EPIT tick (≤200 KB/s even at the 200 kHz ceiling), so the live
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feeder's bounded queue depth of ~150 ms — a few KB in flight — already
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rides out worst-case scheduling latency with orders of magnitude to spare
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(measured: 0.2 ms worst write latency under full CPU + I/O load; the
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underrun bench ran 100 kHz for 120 s with zero underruns). The ring
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itself is 16 MiB (the `ring_mb` module parameter, backed by the 16 MiB
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reserved pool): ~84 s of stream at 200 kHz, ~28 min at the 10 kHz
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cloud-mode tick — a capacity that matters for the whole-job preload of
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cloud mode, not for latency. Bounded queue depth + `SCHED_FIFO` for the
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feeder is the design; revisit RT only if the underrun bench ever
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contradicts this arithmetic.
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6. **gfui-client → forgectrl — DONE.** The stock `gfui-client` is excluded
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from `forgefirm-image` (`IMAGE_INSTALL:remove = "gfui-client"` in
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@@ -73,11 +73,10 @@ repos:
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.:
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# --- meta-openglow — Glowforge BSP layers ---------------------------------
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# ACTIVE DEVELOPMENT: referenced as a local sibling checkout (no url => kas
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# performs no git ops, so the scarthgap-migration edits we're making are what
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# gets built). The kernel-module-glowforge sources are NOT a layer; they are
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# pulled by the kernel-module-glowforge.bb recipe's SRC_URI, so kas does not
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# manage them here.
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# Referenced as a local sibling checkout (no url => kas performs no git ops,
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# so in-place BSP edits are what gets built). The kernel-module-glowforge
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# sources are NOT a layer; the kernel-module-glowforge.bb recipe fetches them
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# by pinned SRCREV, so kas does not manage them here.
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meta-openglow:
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path: ../meta-openglow
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layers:
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@@ -85,11 +84,8 @@ repos:
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meta-glowforge-bsp:
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# meta-openglow-bsp (separate OpenGlow_std board) intentionally excluded.
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#
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# FUTURE — flip to this pinned-remote block at release time (gated on
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# active BSP development settling — see kas/README.md "Push & release order".
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# When flipping, also drop meta-openglow's kernel-module-glowforge.bbappend
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# (externalsrc to the local sibling) so a fresh clone is self-contained; its
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# perl-native DEPENDS is already carried in the base recipe):
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# Pinned-remote alternative for a fully self-contained clone (see
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# kas/README.md "Push & release order"):
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# meta-openglow:
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# url: https://github.com/ScottW514/meta-openglow.git
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# branch: scarthgap # pin via kas lock / a tag at release
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@@ -122,9 +118,7 @@ local_conf_header:
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# release.sh gates the release rootfs against a passwordless root entry.
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build-tweaks: |
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# Parallelism for the 12-core / 16 GB WSL2 VM. (The earlier mid-build deaths
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# were the mirrored-networking vsock relay, not memory — see .wslconfig — so
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# this can comfortably use more of the VM.)
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# Parallelism sized for a 12-core / 16 GB build VM; raise on larger hosts.
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BB_NUMBER_THREADS = "8"
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PARALLEL_MAKE = "-j 8"
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# Caches kept inside the forgefirm repo (gitignored):
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