А что, сайт Gentoo лежит?

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

EAPI=7

inherit kernel-build

MY_P=linux-${PV%.*}
GENPATCHES_P=genpatches-${PV%.*}-${PV##*.}
# https://koji.fedoraproject.org/koji/packageinfo?packageID=8
CONFIG_VER=5.9.2
CONFIG_HASH=94a4277f8827d1b2c911deabe56e7d929dc93146
GENTOO_CONFIG_VER=5.9.8-r1

DESCRIPTION="Linux kernel built with Gentoo patches"
HOMEPAGE="https://www.kernel.org/"
SRC_URI+=" https://cdn.kernel.org/pub/linux/kernel/v$(ver_cut 1).x/${MY_P}.tar.xz
	https://dev.gentoo.org/~mpagano/dist/genpatches/${GENPATCHES_P}.base.tar.xz
	https://dev.gentoo.org/~mpagano/dist/genpatches/${GENPATCHES_P}.extras.tar.xz
	https://github.com/mgorny/gentoo-kernel-config/archive/v${GENTOO_CONFIG_VER}.tar.gz
		-> gentoo-kernel-config-${GENTOO_CONFIG_VER}.tar.gz
	amd64? (
		https://src.fedoraproject.org/rpms/kernel/raw/${CONFIG_HASH}/f/kernel-x86_64-fedora.config
			-> kernel-x86_64-fedora.config.${CONFIG_VER}
	)
	arm64? (
		https://src.fedoraproject.org/rpms/kernel/raw/${CONFIG_HASH}/f/kernel-aarch64-fedora.config
			-> kernel-aarch64-fedora.config.${CONFIG_VER}
	)
	ppc64? (
		https://src.fedoraproject.org/rpms/kernel/raw/${CONFIG_HASH}/f/kernel-ppc64le-fedora.config
			-> kernel-ppc64le-fedora.config.${CONFIG_VER}
	)
	x86? (
		https://src.fedoraproject.org/rpms/kernel/raw/${CONFIG_HASH}/f/kernel-i686-fedora.config
			-> kernel-i686-fedora.config.${CONFIG_VER}
	)"
S=${WORKDIR}/${MY_P}

LICENSE="GPL-2"
KEYWORDS="~amd64 ~arm ~arm64 ~ppc64 ~x86"
IUSE="debug"
REQUIRED_USE="arm? ( savedconfig )"

RDEPEND="
	!sys-kernel/vanilla-kernel:${SLOT}
	!sys-kernel/vanilla-kernel-bin:${SLOT}"
BDEPEND="
	debug? ( dev-util/dwarves )"

src_prepare() {
	local PATCHES=(
		# meh, genpatches have no directory
		"${WORKDIR}"/*.patch
	)
	default

	# prepare the default config
	case ${ARCH} in
		amd64)
			cp "${DISTDIR}/kernel-x86_64-fedora.config.${CONFIG_VER}" .config || die
			;;
		arm)
			return
			;;
		arm64)
			cp "${DISTDIR}/kernel-aarch64-fedora.config.${CONFIG_VER}" .config || die
			;;
		ppc64)
			cp "${DISTDIR}/kernel-ppc64le-fedora.config.${CONFIG_VER}" .config || die
			;;
		x86)
			cp "${DISTDIR}/kernel-i686-fedora.config.${CONFIG_VER}" .config || die
			;;
		*)
			die "Unsupported arch ${ARCH}"
			;;
	esac

	local merge_configs=(
		"${WORKDIR}/gentoo-kernel-config-${GENTOO_CONFIG_VER}"/base.config
	)
	use debug || merge_configs+=(
		"${WORKDIR}/gentoo-kernel-config-${GENTOO_CONFIG_VER}"/no-debug.config
	)
	kernel-build_merge_configs "${merge_configs[@]}"
}