static-build: cross build kernel

Prepare cross build environment based on current Dockerfile.

Fixes: #6557
Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>

tools/packaging/kernel/build-kernel.sh

@@ -65,6 +65,8 @@ kernel_url=""
 #Linux headers for GPU guest fs module building
 linux_headers=""
 
+CROSS_BUILD_ARG=""
+
 MEASURED_ROOTFS=${MEASURED_ROOTFS:-no}
 
 packaging_scripts_dir="${script_dir}/../scripts"
@@ -436,7 +438,7 @@ setup_kernel() {
 
 	info "Copying config file from: ${kernel_config_path}"
 	cp "${kernel_config_path}" ./.config
-	make oldconfig
+	ARCH=${arch_target}  make oldconfig ${CROSS_BUILD_ARG}
 	)
 }
 
@@ -447,7 +449,7 @@ build_kernel() {
 	[ -n "${arch_target}" ] || arch_target="$(uname -m)"
 	arch_target=$(arch_to_kernel "${arch_target}")
 	pushd "${kernel_path}" >>/dev/null
-	make -j $(nproc ${CI:+--ignore 1}) ARCH="${arch_target}"
+	make -j $(nproc ${CI:+--ignore 1}) ARCH="${arch_target}" ${CROSS_BUILD_ARG}
 	if [ "${conf_guest}" == "sev" ]; then
 		make -j $(nproc ${CI:+--ignore 1}) INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=${kernel_path} modules_install
 	fi
@@ -658,6 +660,8 @@ main() {
 
 	info "Kernel version: ${kernel_version}"
 
+	[ "${arch_target}" != "" -a "${arch_target}" != $(uname -m) ] && CROSS_BUILD_ARG="CROSS_COMPILE=${arch_target}-linux-gnu-"
+
 	case "${subcmd}" in
 		build)
 			build_kernel "${kernel_path}"

tools/packaging/kernel/kata_config_version

@@ -1 +1 @@
-111
+112

tools/packaging/static-build/kernel/Dockerfile

@@ -5,6 +5,8 @@
 FROM ubuntu:22.04
 ENV DEBIAN_FRONTEND=noninteractive
 
+ARG ARCH
+
 # kernel deps
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
@@ -23,4 +25,5 @@ RUN apt-get update && \
 	    rsync \
 	    cpio \
 	    patch && \
-    apt-get clean && apt-get autoclean
+    if [ "${ARCH}" != "$(uname -m)" ]; then apt-get install --no-install-recommends -y gcc-"${ARCH}"-linux-gnu binutils-"${ARCH}"-linux-gnu; fi && \
+    apt-get clean && apt-get autoclean && rm -rf /var/lib/apt/lists/*

tools/packaging/static-build/kernel/build.sh

@@ -14,12 +14,26 @@ source "${script_dir}/../../scripts/lib.sh"
 
 readonly kernel_builder="${repo_root_dir}/tools/packaging/kernel/build-kernel.sh"
 
+BUILDX=
+PLATFORM=
+
 DESTDIR=${DESTDIR:-${PWD}}
 PREFIX=${PREFIX:-/opt/kata}
 container_image="${KERNEL_CONTAINER_BUILDER:-$(get_kernel_image_name)}"
 
+if [ "${CROSS_BUILD}" == "true" ]; then
+       container_image="${container_image}-${ARCH}-cross-build"
+       # Need to build a s390x image due to an issue at
+       # https://github.com/kata-containers/kata-containers/pull/6586#issuecomment-1603189242
+       if [ ${ARCH} == "s390x" ]; then
+               BUILDX="buildx"
+               PLATFORM="--platform=linux/s390x"
+       fi
+fi
+
 sudo docker pull ${container_image} || \
-	(sudo docker build -t "${container_image}" "${script_dir}" && \
+	(sudo docker ${BUILDX} build ${PLATFORM} \
+	--build-arg ARCH=${ARCH} -t "${container_image}" "${script_dir}" && \
 	 # No-op unless PUSH_TO_REGISTRY is exported as "yes"
 	 push_to_registry "${container_image}")
 
@@ -27,21 +41,21 @@ sudo docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	--env MEASURED_ROOTFS="${MEASURED_ROOTFS:-}" \
 	"${container_image}" \
-	bash -c "${kernel_builder} $* setup"
+	bash -c "${kernel_builder} -a ${ARCH} $* setup"
 
 sudo docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	"${container_image}" \
-	bash -c "${kernel_builder} $* build"
+	bash -c "${kernel_builder} -a ${ARCH} $* build"
 
 sudo docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	--env DESTDIR="${DESTDIR}" --env PREFIX="${PREFIX}" \
 	"${container_image}" \
-	bash -c "${kernel_builder} $* install"
+	bash -c "${kernel_builder} -a ${ARCH} $* install"
 
 sudo docker run --rm -i -v "${repo_root_dir}:${repo_root_dir}" \
 	-w "${PWD}" \
 	--env DESTDIR="${DESTDIR}" --env PREFIX="${PREFIX}" \
 	"${container_image}" \
-	bash -c "${kernel_builder} $* build-headers"
+	bash -c "${kernel_builder} -a ${ARCH} $* build-headers"