FROM scratch as base
ENV VERSION=6.6
ENV SRC_HASH=d926a06c63dd8ac7df3f86ee1ffc2ce2a3b81a2d168484e76b5b389aba8e56d0
ENV SRC_FILE=linux-${VERSION}.tar.xz
ENV SRC_SITE=http://mirrors.edge.kernel.org/pub/linux/kernel/v6.x/${SRC_FILE}

FROM base as fetch
ADD --checksum=sha256:${SRC_HASH} ${SRC_SITE} .

FROM fetch as build
COPY --from=busybox . /
COPY --from=musl . /
COPY --from=make . /
COPY --from=binutils . /
COPY --from=linux-headers . /
COPY --from=elfutils . /
COPY --from=openssl . /
COPY --from=perl . /
COPY --from=m4 . /
COPY --from=gcc . /
COPY --from=bison . /
COPY --from=libzstd . /
COPY --from=zlib . /
COPY --from=flex . /
COPY --from=pkgconf . /
RUN tar -xf ${SRC_FILE}
WORKDIR linux-${VERSION}
RUN <<-EOF
	set -eux
	make oldconfig
	make
EOF

FROM build as install
RUN <<-EOF
	set -eux
	make DESTDIR=/rootfs install
	mkdir -p /rootfs/usr
EOF
RUN find /rootfs -exec touch -hcd "@0" "{}" +

FROM scratch as package
COPY --from=install /rootfs /