linux/scripts/package/install-extmod-build

#!/bin/sh
# SPDX-License-Identifier: GPL-2.0-only

set -eu

destdir=${1}

is_enabled() {
	grep -q "^$1=y" include/config/auto.conf
}

mkdir -p "${destdir}"

(
	cd "${srctree}"
	echo Makefile
	find "arch/${SRCARCH}" -maxdepth 1 -name 'Makefile*'
	find include scripts -type f -o -type l
	find "arch/${SRCARCH}" -name Kbuild.platforms -o -name Platform
	find "arch/${SRCARCH}" -name include -type d
) | tar -c -f - -C "${srctree}" -T - | tar -xf - -C "${destdir}"

{
	if is_enabled CONFIG_OBJTOOL; then
		echo tools/objtool/objtool
	fi

	find "arch/${SRCARCH}/include" Module.symvers include scripts -type f

	if is_enabled CONFIG_GCC_PLUGINS; then
		find scripts/gcc-plugins -name '*.so'
	fi
} | tar -c -f - -T - | tar -xf - -C "${destdir}"

# copy .config manually to be where it's expected to be
cp "${KCONFIG_CONFIG}" "${destdir}/.config"