| name | jetson-build-source |
| description | >- Use when you need to rebuild the BSP overlay — DT, OOT modules, or kernel — from changes under bsp_sources/. Triggers: build bsp, rebuild dtb, rebuild kernel. |
| version | 0.0.1 |
| license | "Apache-2.0" |
| argument-hint | "dt | oot | kernel | full" |
| metadata | data-classification: public author: "Jetson Team" team: pts tags: - bsp - build domain: meta |
Build BSP Source
Purpose
Rebuild the kernel-side artifacts (DTBs, OOT modules, in-tree
modules, kernel Image) implied by changes under
<source.root_path>/bsp_sources/, and write a manifest that
/jetson-promote-image reads to stage those outputs into the BSP
image. The skill never writes into <bsp_image.root_path> itself.
Prerequisites
- Active target-platform profile with
bsp_image: and
source.toolchain: resolved (run /jetson-init-image and
/jetson-init-source first).
<source.root_path>/bsp_sources/ populated with the kernel-side
checkout layout /jetson-init-source materializes.<bsp_image.root_path>/Linux_for_Tegra/source/kernel_src_build_env.sh
present (extracted from public_sources.tbz2).- Host packages:
flex, bison, libssl-dev (hard); git,
build-essential, bc, zstd (warn-only).
- Cross-toolchain at
${source.toolchain}gcc resolvable on disk.
Overview
This skill is the Build stage of the workflow — see
../../context/bsp-customization-workflow.md
for where it sits in the Setup → Customize → Build → Deploy pipeline
and what triggers it. The skill takes source-side customization
commits, rebuilds the implied artifacts, and records which were
rebuilt in a manifest. Outputs stay in-tree under
<source.root_path>/bsp_sources/;
jetson-promote-image reads the
manifest at Deploy to copy each rebuilt artifact into the matching
path under <bsp_image.root_path>/Linux_for_Tegra/.
Overlay-only edits (nvpmodel.conf, nvfancontrol.conf, BPMP DTB)
skip Build — customize-* stages them directly to the overlay
tracker; BPMP DTB uses the dtc decompile → edit → recompile loop in
../../references/bsp-customization-bpmp-dtb.md.
Custom-overlay slot ownership. Kernel-DT customizations from
every customize-* skill collect into a single composite
tegra<soc>-<carrier-id-sku>+<module-id>-xxxx-custom.dts per
active target — see
../../references/bsp-customization-kernel-dtb.md
for the filename / location / append protocol. This skill is the
sole owner of the composite's per-dir Makefile registration
(dtbo-y += <name>.dtbo) and the carrier flash conf's
OVERLAY_DTB_FILE+= line (the "Register composite custom overlay" step).
Four build modes matched to the dirty-repo profile:
| Mode | What's built | Auto-picks when |
|---|
| dt | NVIDIA DTBs only | only hardware/nvidia/* or kernel-devicetree dirty |
| oot | OOT modules (six repos) | only OOT repos dirty |
| kernel | Kernel Image + full in-tree .ko set + kernel-side dtbs | only kernel/$KERNEL_SRC_DIR dirty |
| full | Everything above + optional install consolidation | mixed dirty set |
Mode selection: auto (default — invoke /jetson-build-source
with no argument) walks the dirty-repo set; force a specific mode
by passing it as the skill argument.
Design principle: delegate to upstream. Every build primitive
already exists in <bsp_image.root_path>/Linux_for_Tegra/source/
— the env file, top-level Makefile (nvidia-dtbs / modules /
modules_install), kernel Makefile (kernel / install). The
skill drives those primitives against
<source.root_path>/bsp_sources/ — never duplicates their
logic in shell.
When to invoke
- Auto-chained at the end of a Customize
customize-* invocation
whenever Customize committed to a kernel-side source repo.
- Manual re-run via
/jetson-build-source [<mode>] when:
- the auto-chained build was interrupted,
- source commits arrived via
git pull from other users,
- the user wants to force a rebuild without a fresh edit,
- the user wants a specific mode (e.g. install consolidation for
a manual scp deploy to a DUT).
Instructions
Resolve active target + paths + upstream env
Resolve the active profile per
../../context/target-platform-contract.md.
Refuse and route in these cases:
| Condition | Route to |
|---|
No active profile, or active: NA | /jetson-set-target or /jetson-init-target |
Profile lacks bsp_image: | /jetson-init-image |
Profile lacks source.toolchain: | /jetson-init-source |
<source.root_path>/bsp_sources/ missing or empty | /jetson-init-source |
<bsp_image.root_path>/Linux_for_Tegra/source/kernel_src_build_env.sh missing | /jetson-init-image (BSP not properly extracted) |
Bind:
WORKSPACE=<parent of target-platform/>
BSP_SRC=<bsp_image.root_path>/Linux_for_Tegra/source
KS=<source.root_path>/bsp_sources
KOUT=<source.root_path>/.build/kernel-out
STAGE=<source.root_path>/.build/install-stage
STATE=<source.root_path>/.build-state.yaml
MANIFEST=<source.root_path>/.build-manifest.yaml
Source the NVIDIA build env to inherit canonical names — never
hardcode kernel-noble, the OOT module list, or KERNEL_DEF_CONFIG:
source "$BSP_SRC/kernel_src_build_env.sh"
Refuse if $KS/kernel/$KERNEL_SRC_DIR/ is missing or if any name
in $OOT_SOURCE_LIST is missing under $KS/. Route to
/jetson-init-source.
Resolve toolchain (read-only)
Read source.toolchain from the active profile (authored by
jetson-init-source). Validate:
export ARCH=arm64
export CROSS_COMPILE=<source.toolchain>
[ -f "${CROSS_COMPILE}gcc" ] || refuse \
"source.toolchain points at ${CROSS_COMPILE}gcc which does not exist. Re-run /jetson-init-source."
A trailing dash on CROSS_COMPILE is mandatory — kbuild treats it
as a prefix (${CROSS_COMPILE}gcc); a missing dash breaks with
command not found. The [ -f ] check catches it before any
make runs.
This skill never prompts for the toolchain or attempts to
resolve a missing one — that's jetson-init-source's exclusive
responsibility. A missing field is a Setup gap; route there.
Verify build-host prerequisites once:
for p in flex bison libssl-dev; do
dpkg -s "$p" >/dev/null 2>&1 || refuse "host package missing: $p"
done
for p in git build-essential bc zstd; do
dpkg -s "$p" >/dev/null 2>&1 || warn "host package missing: $p"
done
Detect dirty source repos
The watermark file $STATE records the last successfully built
commit per kernel-side repo. The repo list is derived at runtime
from OOT_SOURCE_LIST + kernel/$KERNEL_SRC_DIR. For each repo:
HEAD ≠ watermark → dirty; uncommitted edits (git diff --quiet
non-zero) → also dirty.
Branch-A note: when bsp_sources/ is one mono-repo with a
single .git, every canonical sub-path shares the same HEAD —
the watermark schema still keys per-sub-path and the dirty set
still works (any change anywhere flips every sub-path's HEAD).
If STATE is absent (first build), treat all repos as clean
unless the auto-chain context says "Customize just committed". If
DIRTY is empty and no mode argument was passed: report
"nothing to build" and return.
Pick build mode
Map the dirty set to a mode (auto), or honor the mode argument:
| Dirty repos (auto) | Mode |
|---|
Only hardware/nvidia/* or kernel-devicetree | dt |
Only OOT subset of $OOT_SOURCE_LIST | oot |
Only kernel/$KERNEL_SRC_DIR | kernel |
| Any mix spanning the above | full |
Modes are union-able: full runs kernel → oot → dt in that
order (kernel produces headers OOT needs; nvidia-dtbs uses the
same generated headers). A manually passed mode argument skips
auto-detection.
Execute build
Common setup + per-mode build snippets
Common setup (validate orchestrator Makefiles, cd $KS) and the
exact make invocations for each mode (dt, oot, kernel,
full) plus the optional install consolidation pass live in
references/build-modes.md. Drive
the relevant mode's snippet against the bindings from the
"Resolve active target + paths + upstream env" step.
Register composite custom overlay (dt + full only)
Skip unless the selected mode is dt or full. The composite
overlay slot is documented in
../../references/bsp-customization-kernel-dtb.md;
this sub-step owns the build / Makefile / flash-conf side of it.
Resolve the composite path for the active target ($COMPOSITE_BASE,
$COMPOSITE_DTS, $COMPOSITE_MK) using the active profile's
chip family, carrier ID/SKU, and module ID — full snippet in
references/composite-registration.md.
Gate (symmetric). $COMPOSITE_DTS drives both directions:
present → apply the two idempotent patches below; absent → run the
cleanup pass
to strip any stale dtbo-y += / OVERLAY_DTB_FILE+= line from a
prior run. Either path keeps OVERLAY_DTB_FILE+= from referencing
an unbuilt .dtbo — the build-time enforcement of the
no-direct-in-tree-DT-edits rule.
- Per-dir Makefile — append
dtbo-y += <name>.dtbo after the
last literal-named dtbo-y += entry. Inserting after the
$(old-dtbo) merge-back line skips the $(addprefix makefile-path/,…) prefix pass and the build silently drops
the composite. Commit to the bsp_sources/ mono-repo. Full
snippet + rationale:
references/composite-registration.md.
- Carrier flash conf — append
OVERLAY_DTB_FILE+=",<name>.dtbo"
with first-touch pristine import on the overlay tracker. On a
fresh workspace the tracker is empty git-init; import the
conf from bsp_image and commit as pristine: before the
customization commit (workflow contract). Full snippet:
references/composite-registration.md.
The composite's parent sub-repo flipping HEAD during a customize-*
append is what the "Detect dirty source repos" step's dirty detection consumes — no extra
bookkeeping needed here.
Self-check before invoking nvidia-dtbs:
grep -qxF "dtbo-y += ${COMPOSITE_BASE}.dtbo" "$COMPOSITE_MK" \
|| refuse "Composite Makefile registration missing after patch."
grep -qxF "$line" "$FLASH_CONF" \
|| refuse "Composite flash-conf registration missing after patch."
Write the build manifest
Walk the DIRTY set and emit a manifest entry per implied artifact,
following the trace-to-dirty policy — only artifacts traceable
to a dirty source repo. Promoting baseline-divergence noise would
attribute it to a customization's audit trail (forbidden).
The full source → kbuild → destination mapping, YAML schema, and
filter rules live in
references/manifest-schema.md.
Atomic write: stage to ${MANIFEST}.tmp, then mv -f.
Update watermark + summary
On success, rewrite $STATE with the new per-repo HEADs, toolchain,
bsp_image.version, and last-run mode (schema in
references/manifest-schema.md).
Report:
- Toolchain (from
source.toolchain).
- Build mode:
<dt|oot|kernel|full> (auto-picked or forced by skill argument).
- Dirty repos and their new HEADs.
- Artifacts built: counts per kind (
.dtb, in-tree .ko, OOT .ko, Image).
- Manifest path + entry count.
- Consolidated install stage path (if the "Install consolidation" step ran).
- Next step:
/jetson-promote-image.
If a Customize skill triggered this run, prompt the user to re-issue
their original request.
Limitations
The top tier — failure modes that block a build or silently
produce wrong artifacts. See
references/long-tail-gotchas.md
for invariants, deploy patterns, and performance hints.
- Toolchain resolution is
jetson-init-source's job. This
skill only reads source.toolchain and exports CROSS_COMPILE.
Missing field → refuse and route, never resolve in-skill.
- R36.x Branch-A
$KS/Makefile collision. R36.x's
public_sources.tbz2 can leave the dGPU/OpenRM proprietary
Makefile at $KS/Makefile instead of the Tegra orchestrator;
its modules target recurses into kernel-open/ + src/nvidia/,
pulls host /lib/modules headers, and breaks arm64 cross-builds
with '-mlittle-endian' unrecognized. R38+ extractions are
unaffected. /jetson-init-source's step 3a is the primary defense
(extract-time); the "Common setup" check here is the safety net.
Don't relax the regex.
- Kernel-DT changes: composite-overlay-only, split ownership.
Direct edits to in-tree
.dts / .dtsi files under bsp_sources/
are forbidden for customize-* skills — every kernel-DT change
lands as a fragment in the composite overlay slot
(rule + rationale).
The composite .dts content is owned by each customize-*
skill; the build / Makefile / flash-conf registration is
owned by this skill (gated on the composite .dts existing — so
OVERLAY_DTB_FILE+= can't reference an unbuilt .dtbo).
- the "Register composite custom overlay" step Makefile insertion point matters. Insert after
the last literal-named
dtbo-y += entry; inserting after
$(old-dtbo) skips the $(addprefix makefile-path/,…) prefix
pass and the build silently drops your .dtbo. The regex
^dtbo-y *+= *[a-zA-Z0-9] filters correctly; do not relax it.
- the "Register composite custom overlay" step first-touch needs pristine import. On a fresh
workspace the overlay tracker is empty git-init — the carrier
flash conf is imported from
bsp_image and committed as
pristine: before the customization commit. Both commits go
through the workflow acceptance gate.
- Avoid bare
$0 in shell snippets inside this SKILL.md. When
invoked with an argument, the harness expands skill-body $0
against the caller's $0 before handing the rendered prompt to
the model. Use sed-based line splicing or
awk -v ROW="$0". See
references/composite-registration.md.
- No overlay staging. Build outputs stay where the build put
them; the manifest is the contract to
jetson-promote-image.
Deliberate divergence from the original overlay→promote
indirection — keeps the full build output set out of the
overlay tracker's git history.
KERNEL_HEADERS vs KERNEL_OUTPUT in DT mode. Different
semantics (srctree vs objtree); do not collapse. the "DT-only" step's
snippet is correct as written.- OOT mode prereq: previously-built kernel headers. A manual
oot invocation against a never-built tree refuses with "run
kernel (or full) first" rather than producing a confusing
build error.
Examples
Auto-detect mode from the dirty source tree (typical invocation):
/jetson-build-source
Force a single mode (skips auto-detect):
/jetson-build-source dt # rebuild NVIDIA DTBs only
/jetson-build-source oot # rebuild OOT modules only
/jetson-build-source kernel # rebuild kernel Image + in-tree modules
/jetson-build-source full # rebuild everything + install consolidation
Typical chain after a customize-* skill commits to a kernel-side
repo (the customize-* skill calls this automatically):
/jetson-customize-pcie ... # commits to hardware/nvidia/.../nv-public
↓
/jetson-build-source # auto-picks `dt` from the dirty set
↓
/jetson-promote-image # reads .build-manifest.yaml, stages into bsp_image
↓
/jetson-flash-image # flashes
Troubleshooting
| Error | Cause | Solution |
|---|
source.toolchain points at <...>gcc which does not exist | Toolchain field stale (path moved, install missing) | Re-run /jetson-init-source to re-resolve. This skill never resolves toolchain itself. |
No rule to make target '$KOUT/scripts/Makefile.compiler' | KERNEL_HEADERS set to $KOUT instead of $KS/kernel/$KERNEL_SRC_DIR | Use the DT-mode snippet in references/build-modes.md verbatim — srctree vs objtree must not collapse. |
'-mlittle-endian' unrecognized during make modules | R36.x Branch-A $KS/Makefile collision — dGPU/OpenRM Makefile in place of Tegra orchestrator | The Common-setup safety net normally repairs it; if not, git checkout HEAD -- Makefile then re-run /jetson-init-source step 3a. |
run kernel (or full) first on manual oot invocation | Kernel source tree never prepared | Run /jetson-build-source kernel (or full) once, then oot. |
nothing to build and dirty edits exist | Edits uncommitted in a sub-repo but .build-state.yaml watermark already matches HEAD | Commit the edits, or re-run with an explicit mode argument (/jetson-build-source dt etc.). |
Composite .dtbo silently missing from the output set | Per-dir Makefile insertion landed after $(old-dtbo) merge-back line | See references/composite-registration.md — insert after the last literal-named dtbo-y += entry. |
| Promote step copies stale baseline artifacts | Trace-to-dirty filter skipped after a manual cp into $KS | Only edit via a customize-* skill or git; the dirty detector keys on git HEAD, not file mtime. |
host package missing: <pkg> | flex/bison/libssl-dev refuse; others warn. | sudo apt install <pkg> per references/upstream-recipe.md. |
See also
