kernel-install.eclass

# Copyright 2020 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

# @ECLASS: kernel-install.eclass
# @MAINTAINER:
# Distribution Kernel Project <dist-kernel@gentoo.org>
# @AUTHOR:
# Michał Górny <mgorny@gentoo.org>
# @SUPPORTED_EAPIS: 7
# @BLURB: Installation mechanics for Distribution Kernels
# @DESCRIPTION:
# This eclass provides the logic needed to test and install different
# kinds of Distribution Kernel packages, including both kernels built
# from source and distributed as binaries.  The eclass relies on the
# ebuild installing a subset of built kernel tree into
# /usr/src/linux-${PV} containing the kernel image in its standard
# location and System.map.
#
# The eclass exports src_test, pkg_postinst and pkg_postrm.
# Additionally, the inherited mount-boot eclass exports pkg_pretend.
# It also stubs out pkg_preinst and pkg_prerm defined by mount-boot.

if [[ ! ${_KERNEL_INSTALL_ECLASS} ]]; then

case "${EAPI:-0}" in
	0|1|2|3|4|5|6)
		die "Unsupported EAPI=${EAPI:-0} (too old) for ${ECLASS}"
		;;
	7)
		;;
	*)
		die "Unsupported EAPI=${EAPI} (unknown) for ${ECLASS}"
		;;
esac

inherit mount-boot

TCL_VER=10.1
SRC_URI+="
	test? (
		amd64? (
			https://dev.gentoo.org/~mgorny/dist/tinycorelinux-${TCL_VER}-amd64.qcow2
		)
		x86? (
				https://dev.gentoo.org/~mgorny/dist/tinycorelinux-${TCL_VER}-x86.qcow2
		)
	)"

SLOT="${PV}"
IUSE="+initramfs test"
RESTRICT+=" !test? ( test ) test? ( userpriv )"

# install-DEPEND actually
# note: we need installkernel with initramfs support!
RDEPEND="
	|| (
		sys-kernel/installkernel-gentoo
		sys-kernel/installkernel-systemd-boot
	)
	initramfs? ( >=sys-kernel/dracut-049-r3 )"
BDEPEND="
	test? (
		dev-tcltk/expect
		sys-kernel/dracut
		amd64? ( app-emulation/qemu[qemu_softmmu_targets_x86_64] )
		x86? ( app-emulation/qemu[qemu_softmmu_targets_i386] )
	)"

# @FUNCTION: kernel-install_build_initramfs
# @USAGE: <output> <version>
# @DESCRIPTION:
# Build an initramfs for the kernel.  <output> specifies the absolute
# path where initramfs will be created, while <version> specifies
# the kernel version, used to find modules.
kernel-install_build_initramfs() {
	debug-print-function ${FUNCNAME} "${@}"

	[[ ${#} -eq 2 ]] || die "${FUNCNAME}: invalid arguments"
	local output=${1}
	local version=${2}

	ebegin "Building initramfs via dracut"
	dracut --force "${output}" "${version}"
	eend ${?} || die "Building initramfs failed"
}

# @FUNCTION: kernel-install_get_image_path
# @DESCRIPTION:
# Get relative kernel image path specific to the current ${ARCH}.
kernel-install_get_image_path() {
	case ${ARCH} in
		amd64|x86)
			echo arch/x86/boot/bzImage
			;;
		*)
			die "${FUNCNAME}: unsupported ARCH=${ARCH}"
			;;
	esac
}

# @FUNCTION: kernel-install_install_kernel
# @USAGE: <version> <image> <system.map>
# @DESCRIPTION:
# Install kernel using installkernel tool.  <version> specifies
# the kernel version, <image> full path to the image, <system.map>
# full path to System.map.
kernel-install_install_kernel() {
	debug-print-function ${FUNCNAME} "${@}"

	[[ ${#} -eq 3 ]] || die "${FUNCNAME}: invalid arguments"
	local version=${1}
	local image=${2}
	local map=${3}

	ebegin "Installing the kernel via installkernel"
	# note: .config is taken relatively to System.map;
	# initrd relatively to bzImage
	installkernel "${version}" "${image}" "${map}"
	eend ${?} || die "Installing the kernel failed"
}

# @FUNCTION: kernel-install_update_symlink
# @USAGE: <target> <version>
# @DESCRIPTION:
# Update the kernel source symlink at <target> (full path) with a link
# to <target>-<version> if it's either missing or pointing out to
# an older version of this package.
kernel-install_update_symlink() {
	debug-print-function ${FUNCNAME} "${@}"

	[[ ${#} -eq 2 ]] || die "${FUNCNAME}: invalid arguments"
	local target=${1}
	local version=${2}

	if [[ ! -e ${target} ]]; then
		ebegin "Creating ${target} symlink"
		ln -f -n -s "${target##*/}-${version}" "${target}"
		eend ${?}
	else
		local symlink_target=$(readlink "${target}")
		local symlink_ver=${symlink_target#${target##*/}-}
		if [[ ${symlink_target} == ${target##*/}-* && \
				-z ${symlink_ver//[0-9.]/} ]]
		then
			local symlink_pkg=${CATEGORY}/${PN}-${symlink_ver}
			# if the current target is either being replaced, or still
			# installed (probably depclean candidate), update the symlink
			if has "${symlink_ver}" ${REPLACING_VERSIONS} ||
					has_version -r "~${symlink_pkg}"
			then
				ebegin "Updating ${target} symlink"
				ln -f -n -s "${target##*/}-${version}" "${target}"
				eend ${?}
			fi
		fi
	fi
}

# @FUNCTION: kernel-install_get_qemu_arch
# @DESCRIPTION:
# Get appropriate qemu suffix for the current ${ARCH}.
kernel-install_get_qemu_arch() {
	debug-print-function ${FUNCNAME} "${@}"

	case ${ARCH} in
		amd64)
			echo x86_64
			;;
		x86)
			echo i386
			;;
		*)
			die "${FUNCNAME}: unsupported ARCH=${ARCH}"
			;;
	esac
}

# @FUNCTION: kernel-install_test
# @USAGE: <version> <image> <modules>
# @DESCRIPTION:
# Test that the kernel can successfully boot a minimal system image
# in qemu.  <version> is the kernel version, <image> path to the image,
# <modules> path to module tree.
kernel-install_test() {
	debug-print-function ${FUNCNAME} "${@}"

	[[ ${#} -eq 3 ]] || die "${FUNCNAME}: invalid arguments"
	local version=${1}
	local image=${2}
	local modules=${3}

	local qemu_arch=$(kernel-install_get_qemu_arch)

	dracut \
		--conf /dev/null \
		--confdir /dev/null \
		--no-hostonly \
		--kmoddir "${modules}" \
		"${T}/initrd" "${version}" || die
	# get a read-write copy of the disk image
	cp "${DISTDIR}/tinycorelinux-${TCL_VER}-${ARCH}.qcow2" \
		"${T}/fs.qcow2" || die

	cd "${T}" || die
	cat > run.sh <<-EOF || die
		#!/bin/sh
		exec qemu-system-${qemu_arch} \
			-m 256M \
			-display none \
			-no-reboot \
			-kernel '${image}' \
			-initrd '${T}/initrd' \
			-serial mon:stdio \
			-hda '${T}/fs.qcow2' \
			-append 'root=/dev/sda console=ttyS0,115200n8'
	EOF
	chmod +x run.sh || die
	# TODO: initramfs does not let core finish starting on some systems,
	# figure out how to make it better at that
	expect - <<-EOF || die "Booting kernel failed"
		set timeout 900
		spawn ./run.sh
		expect {
			"Kernel panic" {
				send_error "\n* Kernel panic"
				exit 1
			}
			"Entering emergency mode" {
				send_error "\n* Initramfs failed to start the system"
				exit 1
			}
			"Core 10.1" {
				send_error "\n* Booted successfully"
				exit 0
			}
			timeout {
				send_error "\n* Kernel boot timed out"
				exit 2
			}
		}
	EOF
}

# @FUNCTION: kernel-install_src_test
# @DESCRIPTION:
# Boilerplate function to remind people to call the tests.
kernel-install_src_test() {
	debug-print-function ${FUNCNAME} "${@}"

	die "Please redefine src_test() and call kernel-install_test()."
}

# @FUNCTION: kernel-install_pkg_preinst
# @DESCRIPTION:
# Stub out mount-boot.eclass.
kernel-install_pkg_preinst() {
	debug-print-function ${FUNCNAME} "${@}"

	# (no-op)
}

# @FUNCTION: kernel-install_pkg_postinst
# @DESCRIPTION:
# Build an initramfs for the kernel, install it and update
# the /usr/src/linux symlink.
kernel-install_pkg_postinst() {
	debug-print-function ${FUNCNAME} "${@}"

	if [[ -z ${ROOT} ]]; then
		mount-boot_pkg_preinst

		local image_path=$(kernel-install_get_image_path)
		if use initramfs; then
			# putting it alongside kernel image as 'initrd' makes
			# kernel-install happier
			kernel-install_build_initramfs \
				"${EROOT}/usr/src/linux-${PV}/${image_path%/*}/initrd" \
				"${PV}"
		fi

		kernel-install_install_kernel "${PV}" \
			"${EROOT}/usr/src/linux-${PV}/${image_path}" \
			"${EROOT}/usr/src/linux-${PV}/System.map"
	fi

	kernel-install_update_symlink "${EROOT}/usr/src/linux" "${PV}"
}

# @FUNCTION: kernel-install_pkg_prerm
# @DESCRIPTION:
# Stub out mount-boot.eclass.
kernel-install_pkg_prerm() {
	debug-print-function ${FUNCNAME} "${@}"

	# (no-op)
}

# @FUNCTION: kernel-install_pkg_postrm
# @DESCRIPTION:
# No-op at the moment.  Will be used to remove obsolete kernels
# in the future.
kernel-install_pkg_postrm() {
	debug-print-function ${FUNCNAME} "${@}"

	if [[ -z ${ROOT} ]] && use initramfs; then
		local image_path=$(kernel-install_get_image_path)
		ebegin "Removing initramfs"
		rm -f "${EROOT}/usr/src/linux-${PV}/${image_path%/*}/initrd" &&
			find "${EROOT}/usr/src/linux-${PV}" -depth -type d -empty -delete
		eend ${?}
	fi
}

_KERNEL_INSTALL_ECLASS=1
fi

EXPORT_FUNCTIONS src_test pkg_preinst pkg_postinst pkg_prerm pkg_postrm