kbuild

#!/bin/bash
# Author: Pasha Tatashin <pasha.tatashin@soleen.com>
set -e

M="x86_64"
FORCE=0

usage() {
	cat << EOF
Usage: $0 [-a ARCH] [-f] [-h]

Builds lightweight with virtualization extensions kernel for ARCH (default: $M)
outside of source tree. Optioanlly, adds configs in pub/pub.config.

Supported ARCH: x86_64, arm64.
Auto-configures if ARCH/.config is missing or -f is used.

Options:
  -a ARCH   Target architecture (x86_64 or arm64). Defaults to $M.
  -f        Force clean (mrproper) and re-configure the build.
  -h        Show this help message and exit.
EOF
	# Exit with 0 if called via -h, 1 otherwise
	[[ "$1" == "h" ]] && exit 0 || exit 1
}

configure_build() {
	$MAKE mrproper
	$MAKE defconfig
	if [ -f pub/pub.config ]; then
		cat pub/pub.config >> "$M/.config"
		$MAKE olddefconfig
	fi
	$MAKE kvm_guest.config
}

while getopts "a:fh" o; do
	case "${o}" in
		a)
			M="${OPTARG}"
			;;
		f)
			FORCE=1
			;;
		h)
			usage "h"
			;;
		*)
			usage
			;;
	esac
done
shift $((OPTIND-1))

if [[ $# -gt 0 ]]; then
	echo "Error: Unexpected arguments: $*" >&2
	usage
fi

if [[ "$M" == "x86_64" ]]; then
	unset CROSS_COMPILE
elif [[ "$M" == "arm64" ]]; then
	export CROSS_COMPILE=aarch64-linux-gnu-
else
	echo "Error: Invalid architecture '$M'. Please use 'x86_64' or 'arm64'." >&2
	usage # Exit with usage help
fi

# Define the base make command
MAKE="make -k O=$M ARCH=$M -s -j $(nproc)"
CONFIG_PATH="$M/.config"

if [[ "$FORCE" == "1" || ! -f "$CONFIG_PATH" ]]; then
	mkdir -p "$M"
	configure_build
fi

time $MAKE