#!/usr/bin/ksh93

#

# Build Debian RT kernel from source,

# and retain the kernel build including source and *.o

# files so we can build custom kernel modules from

# that

#

compound bconfig=(

	# config

	typeset kernel_maj_min='5.10'

	# 32bit == 'config.i386_rt_686-pae', 64bit == 'config.amd64_rt_amd64'

	typeset kernel_config_name='config.amd64_rt_amd64'

	# calculated values

	typeset kernel_build_path

)

function build_debian_kernel_from_src

{

	set -o xtrace

	set -o errexit

	set -o nounset

	integer res

	integer num_cpus=$(getconf '_NPROCESSORS_CONF')

	tar xf "/usr/src/linux-source-${bconfig.kernel_maj_min}.tar.xz"

	cd "linux-source-${bconfig.kernel_maj_min}"

	unxz <"/usr/src/linux-patch-${bconfig.kernel_maj_min}-rt.patch.xz" | patch -p1

	cp "/usr/src/linux-config-${bconfig.kernel_maj_min}/${bconfig.kernel_config_name}.xz" .

	unxz "${bconfig.kernel_config_name}.xz"

	# copy config and make kernel build accept it without

	# jumping to the $ make menu # menu

	cp "${bconfig.kernel_config_name}" '.config'

	make oldconfig <'/dev/null'

	# show any modifications $ make oldconfig # did to the kernel config

	print '--------------------------------------'

	diff -u "${bconfig.kernel_config_name}" '.config' || true

	print '--------------------------------------'

	make clean

	time nice -n 19 make -j$((num_cpus*4)) deb-pkg 2>&1 | tee -a buildlog.log

	(( res=$? ))

	printf '#### Kernel build finished, return code = %d\n' res

	if (( res == 0 )) ; then

		# remember the path to the kernel build, but only if we were successful

		bconfig.kernel_build_path="$PWD/"

	fi

	return $res

}

function build_simatic_kernel_modules

{

	set -o xtrace

	set -o errexit

	set -o nounset

	# dummy for now

	rm -Rf simatic_build

	mkdir simatic_build

	cd simatic_build

	cp "${bconfig.simatic_src_gitbundle}" .

	git clone rovema_simatickernelmodules_git20220304_001.bundle

	cd rovema_simatickernelmodules_git20220304_001/simatic-ipc-modules-lsp-v1.2.0RC1/

	make -C "${bconfig.kernel_build_path}" KSRC="${bconfig.kernel_build_path}" M=$PWD

	#

	# ToDo: Install in root/ dir, and turn that filesystem hieracy into a

	# Debian package

	# see https://unix.stackexchange.com/questions/30303/how-to-create-a-deb-file-manually

	#

	return 1

}

function build_igb_avb_kernel_module

{

	set -o xtrace

	set -o errexit

	set -o nounset

	rm -Rf igb_avb_build

	mkdir igb_avb_build

	cd igb_avb_build

	cp "${bconfig.igb_avb_src_gitbundle}" .

	git clone rovema_igb_avb_git20220302_001.bundle

	cd rovema_igb_avb_git20220302_001/kmod

	make -C "${bconfig.kernel_build_path}" KSRC="${bconfig.kernel_build_path}" M=$PWD clean

	make -C ${bconfig.kernel_build_path} KSRC="${bconfig.kernel_build_path}" M=$PWD

	cd ../lib

	make

	#

	# ToDo: Install in root/ dir, and turn that filesystem hieracy into a

	# Debian package

	#

	# dummy for now

	# see https://unix.stackexchange.com/questions/30303/how-to-create-a-deb-file-manually

	return 1

}

function main

{

	set -o xtrace

	set -o errexit

	set -o nounset

	typeset bbd="$PWD" # base build directory

	if (( 1 )) ; then

		cd $bbd && build_debian_kernel_from_src

	else

		bconfig.kernel_build_path="$PWD/linux-source-${bconfig.kernel_maj_min}/"

	fi

	cd $bbd ; build_simatic_kernel_modules || true

	cd $bbd ; build_igb_avb_kernel_module

}

#

# main

#

builtin getconf

main "$@"

# EOF.