Build PX4 on Linux

Inputs

• A make target, for example px4_fmu-v6x_default or px4_sitl. Ask for it if missing; validate it against boards/.

Build the current checkout as-is, worktree or not. Do not create a worktree or switch branches to build.

Prepare

1. arm-none-eabi-gcc --version must succeed for NuttX targets. If it does not, the host needs Tools/setup/ubuntu.sh (Ubuntu) — tell the user rather than installing it, or build in the container: docker run --rm -w "$PWD" --user "$(id -u):$(id -g)" -v "$PWD:$PWD" px4io/px4-dev:v1.17.0 make <target>. Tools/docker_run.sh passes -it and fails without a TTY.
2. The build initializes submodules itself; do not overwrite locally modified ones.

Build

set -o pipefail
make <target> 2>&1 | tail -n 40

Report failures with the output; never treat an existing artifact as evidence of success. After changing a defconfig or Kconfig option, or switching toolchains, rm -rf build/<target> first: a stale build dir recompiles nothing and links mixed objects.

Do not run a NuttX build concurrently with make tests or SITL in the same tree.

Report

The artifact is build/<target>/<target>.px4 (NuttX) or build/px4_sitl_default/bin/px4 (SITL). Report the ref, commit, dirty state, target, and artifact path. Building is not flashing; never upload without a separate request.