/etc/portage/env/sys-kernel/gentoo-kernel

etcportageenvsys-kernelgentoo-kernel

# place this file to /etc/portage/env/sys-kernel/gentoo-kernel
# please, pre-fetch zfs tarball, like 'emerge zfs-kmod --fetchonly'
# also make sure that $PORTAGE_TMPDIR/portage/sys-fs/zfs-kmod* is not present

# simply set to false if not needed
: "${__EZFS_KERNEL_BUILTIN:=true}"

__ORIG_DISTDIR="${PORTAGE_ACTUAL_DISTDIR:-${DISTDIR}}"

post_src_unpack() {

	[[ ${__EZFS_KERNEL_BUILTIN} == true ]] || return

	ebegin "zfs-builtin: hooked by ${BASH_SOURCE[0]} in ${FUNCNAME[0]}"

	# this will obey keywords/masks, so make sure you have
	# it in sync with sys-fs/zfs
	# eg sys-fs/zfs-kmod-0.8.4-r1
	best_zfs_kmod="$(portageq best_visible ${EROOT%/}/ zfs-kmod 2>/dev/null)"
	einfo "zfs-builtin: will embed ${best_zfs_kmod} into linux source"	
	local orig_distdir zsrc_uri zdistfile
	
	orig_distdir="${__ORIG_DISTDIR}"
	zsrc_uri="$(portageq metadata ${EROOT%/}/ ebuild ${best_zfs_kmod} SRC_URI 2>/dev/null)"
	zdistfile="${zsrc_uri##*/}" # eg zfs-0.8.4.tar.gz
	
	# we need to copy it to tmpdir for further use below
	einfo "zfs-builtin: getting ${zdistfile}"
	cp -v "${orig_distdir}/${zdistfile}" "${T}" || die

	eend ${?}
}


post_src_configure() {
	
	[[ ${__EZFS_KERNEL_BUILTIN} == true ]] || return

	ebegin "zfs-builtin: hooked by ${BASH_SOURCE[0]} in ${FUNCNAME[0]}"

	local repo zpvr zpv zp

	repo="$(portageq get_repo_path ${EROOT%/}/ gentoo 2>/dev/null)" # eg /var/db/repos/gentoo
	zpvr="${best_zfs_kmod#*/}" # eg zfs-kmod-0.8.4-r1
	zp="${zpvr%-r*}" # eg zfs-kmod-0.8.4
	zpv="${zp#zfs-kmod-}" # eg 0.8.4
	zpv="${zpv%_rc*}" # unpacked directories never contain rcX suffix


	# we want to run this in a subshell to prevent env pollution
	# it still receives current env and subshell die works in EAPI=7
	(
	pushd "${repo}" > /dev/null || die

	# turn off some features, since we already sandboxed.
	# we have to pass DISTDIR here so it can find zfs tarball.
	FEATURES="-cgroup -ipc-sandbox -mount-sandbox -pid-sandbox" \
		KERNEL_DIR="${WORKDIR}/${MY_P}" KBUILD_OUTPUT="${WORKDIR}/modprep" \
		DISTDIR="${T}" EXTRA_ECONF="--enable-linux-builtin\
		--with-linux="${WORKDIR}/${MY_P}"\
		--with-linux-obj="${WORKDIR}"/modprep"\
		ebuild sys-fs/zfs-kmod/"${zpvr}".ebuild clean configure || die
	popd > /dev/null || die

	pushd "${PORTAGE_TMPDIR}/portage/${best_zfs_kmod}/work/zfs-${zpv}" > /dev/null || die
	./copy-builtin "${WORKDIR}/${MY_P}" || die
	popd > /dev/null || die
	)
	# end subshell

	einfo "zfs-builtin: ${zpvr} embedded into ${WORKDIR}/${MY_P}"

	# we now have to re-run configure phase with zfs enabled, so start clean
	# this is not really required, but better be safe
	rm -rf "${WORKDIR}"/build || die
	emake O="${WORKDIR}"/modprep "${MAKEARGS[@]}" clean
	emake O="${WORKDIR}"/modprep "${MAKEARGS[@]}" olddefconfig

	# it may be disabled if not restored from savedconfig
	einfo "zfs-builtin: enabling CONFIG_ZFS=y in case it's disabled"
	sed -i 's/# CONFIG_ZFS is not set/CONFIG_ZFS=y/' "${WORKDIR}"/modprep/.config || die

	emake O="${WORKDIR}"/modprep "${MAKEARGS[@]}" olddefconfig
	emake O="${WORKDIR}"/modprep "${MAKEARGS[@]}" modules_prepare
	cp -pR "${WORKDIR}"/modprep "${WORKDIR}"/build || die
	einfo "zfs-builtin: ZFSification done"
	eend ${?}
}

post_src_install() {

	[[ ${__EZFS_KERNEL_BUILTIN} == true ]] || return
	
	ebegin "zfs-builtin: hooked by ${BASH_SOURCE[0]} in ${FUNCNAME[0]}"

	# now it's safe to delete source
	# not needed to keep tree with zfs-2*, but does not hurt ether
	# https://github.com/openzfs/zfs/commit/71504277ae5537007a99864e53a3b5ceb211a660
	[[ -d "${PORTAGE_TMPDIR}/portage/${best_zfs_kmod}" ]] &&\
		{ rm -rf "${PORTAGE_TMPDIR}/portage/${best_zfs_kmod}" || die ; }
	einfo "zfs-builtin: ZFS src cleanup done"

	eend ${?}
}