diff --git a/sdk_container/src/third_party/portage-stable/eclass/linux-mod-r1.eclass b/sdk_container/src/third_party/portage-stable/eclass/linux-mod-r1.eclass
index 16c280219e..91dca82c8f 100644
--- a/sdk_container/src/third_party/portage-stable/eclass/linux-mod-r1.eclass
+++ b/sdk_container/src/third_party/portage-stable/eclass/linux-mod-r1.eclass
@@ -351,6 +351,8 @@ linux-mod-r1_pkg_setup() {
 
 	_modules_set_makeargs
 
+	_modules_prepare_cross
+
 	_modules_sanity_gccplugins
 }
 
@@ -668,6 +670,36 @@ _modules_check_migration() {
 	# - ECONF_PARAMS: documented but was a no-op in linux-mod too
 }
 
+# @FUNCTION: _modules_prepare_cross
+# @INTERNAL
+# @DESCRIPTION:
+# Checks whether modpost works locally as it might have been built for a
+# different architecture.  If it doesn't work, it is built in a new
+# environment and KV_OUT_DIR is repointed there.
+_modules_prepare_cross() {
+	# modpost should do nothing successfully when called without args.
+	if ! "${KV_OUT_DIR}"/scripts/mod/modpost &>/dev/null; then
+		# Try to run make modules_prepare in a new separate output directory.
+		# This cannot be done if the source directory is not clean. In that
+		# case, copy the whole source directory.
+		if [[ -e ${KV_DIR}/.config ]]; then
+			cp -rLT --reflink=auto -- "${KV_DIR}" "${WORKDIR}"/extmod-build || die
+			emake -C "${WORKDIR}"/extmod-build "${MODULES_MAKEARGS[@]}" modules_prepare \
+				KBUILD_OUTPUT=
+		else
+			mkdir -- "${WORKDIR}"/extmod-build || die
+			cp -- "${KV_OUT_DIR}"/{.config,Module.symvers} "${WORKDIR}"/extmod-build || die
+			# KV_OUT_DIR may have been prepared with install-extmod-build, which
+			# doesn't include all the files needed to call make modules_prepare,
+			# so use the Makefile from the full kernel sources.
+			emake -C "${WORKDIR}"/extmod-build "${MODULES_MAKEARGS[@]}" modules_prepare \
+				KBUILD_OUTPUT="${WORKDIR}"/extmod-build -f "${KERNEL_MAKEFILE}"
+		fi
+		KV_OUT_DIR=${WORKDIR}/extmod-build
+		KBUILD_OUTPUT=${KBUILD_OUTPUT+${KV_OUT_DIR}}
+	fi
+}
+
 # @FUNCTION: _modules_prepare_kernel
 # @INTERNAL
 # @DESCRIPTION:
@@ -1259,6 +1291,7 @@ _modules_set_makeargs() {
 		# unrealistic when building modules that often have slow releases,
 		# but note that the kernel will still pass some -Werror=bad-thing
 		CONFIG_WERROR=
+		CONFIG_OBJTOOL_WERROR=
 
 		# these are only needed if using these arguments for installing, lets
 		# eclass handle strip, sign, compress, and depmod (CONFIG_ should