From 578678e0510b6b5f422dc16975a07ad7b15274a4 Mon Sep 17 00:00:00 2001
From: Jakob Naucke <jakob.naucke@ibm.com>
Date: Tue, 15 Feb 2022 19:12:41 +0100
Subject: [PATCH] packaging: Enable cross-building agent

Requires setting ARCH and CC.

- Add CC linker option for building agent.
- Set host for building libseccomp.

Fixes: #3681
Signed-off-by: Jakob Naucke <jakob.naucke@ibm.com>
---
 ci/install_libseccomp.sh |  8 +++++---
 utils.mk                 | 11 ++++++++++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/ci/install_libseccomp.sh b/ci/install_libseccomp.sh
index 8933438860..5cbf8f0798 100755
--- a/ci/install_libseccomp.sh
+++ b/ci/install_libseccomp.sh
@@ -19,7 +19,7 @@ source "${tests_repo_dir}/.ci/lib.sh"
 # fail. So let's ensure they are unset here.
 unset PREFIX DESTDIR
 
-arch=$(uname -m)
+arch=${ARCH:-$(uname -m)}
 workdir="$(mktemp -d --tmpdir build-libseccomp.XXXXX)"
 
 # Variables for libseccomp
@@ -70,7 +70,9 @@ build_and_install_gperf() {
     curl -sLO "${gperf_tarball_url}"
     tar -xf "${gperf_tarball}"
     pushd "gperf-${gperf_version}"
-    ./configure --prefix="${gperf_install_dir}"
+    # gperf is a build time dependency of libseccomp and not to be used in the target.
+    # Unset $CC since that might point to a cross compiler.
+    CC= ./configure --prefix="${gperf_install_dir}"
     make
     make install
     export PATH=$PATH:"${gperf_install_dir}"/bin
@@ -84,7 +86,7 @@ build_and_install_libseccomp() {
     curl -sLO "${libseccomp_tarball_url}"
     tar -xf "${libseccomp_tarball}"
     pushd "libseccomp-${libseccomp_version}"
-    ./configure --prefix="${libseccomp_install_dir}" CFLAGS="${cflags}" --enable-static
+    ./configure --prefix="${libseccomp_install_dir}" CFLAGS="${cflags}" --enable-static --host="${arch}"
     make
     make install
     popd
diff --git a/utils.mk b/utils.mk
index e833b40d7a..3816fac2a1 100644
--- a/utils.mk
+++ b/utils.mk
@@ -112,8 +112,9 @@ endef
 ##VAR BUILD_TYPE=release|debug type of rust build
 BUILD_TYPE = release
 
+HOST_ARCH = $(shell uname -m)
 ##VAR ARCH=arch target to build (format: uname -m)
-ARCH = $(shell uname -m)
+ARCH ?= $(HOST_ARCH)
 ##VAR LIBC=musl|gnu
 LIBC ?= musl
 ifneq ($(LIBC),musl)
@@ -142,6 +143,14 @@ ifeq ($(ARCH), aarch64)
     $(warning "WARNING: aarch64-musl needs extra symbols from libgcc")
 endif
 
+ifneq ($(HOST_ARCH),$(ARCH))
+    ifeq ($(CC),)
+         CC = gcc
+         $(warning "WARNING: A foreign ARCH was passed, but no CC alternative. Using $(CC).")
+    endif
+    override EXTRA_RUSTFLAGS += -C linker=$(CC)
+endif
+
 TRIPLE = $(ARCH)-unknown-linux-$(LIBC)
 
 CWD := $(shell dirname $(realpath $(firstword $(MAKEFILE_LIST))))