Handle building on different architectures

.gitignore

@@ -6,7 +6,6 @@ build-*/
 CMakeCache.txt
 CMakeFiles/
 cmake_install.cmake
-Makefile
 install_manifest.txt
 kobo-pkg/
 *.tgz

Dockerfile.cross

@@ -52,11 +52,13 @@ FROM ubuntu:24.04 AS qt-target-builder
 ENV DEBIAN_FRONTEND=noninteractive
 ENV QT_VERSION=6.5.2
 
-# armhf packages live on ports.ubuntu.com, not archive.ubuntu.com
+# On amd64: archive.ubuntu.com only serves amd64, so add ports for armhf.
 RUN dpkg --add-architecture armhf \
-    && sed -i 's/^Types:/Architectures: amd64\nTypes:/' /etc/apt/sources.list.d/ubuntu.sources \
-    && printf 'Types: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble noble-updates noble-backports\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n\nTypes: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble-security\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n' \
-        > /etc/apt/sources.list.d/armhf-ports.sources \
+    && if [ "$(dpkg --print-architecture)" = "amd64" ]; then \
+        sed -i 's/^Types:/Architectures: amd64\nTypes:/' /etc/apt/sources.list.d/ubuntu.sources; \
+        printf 'Types: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble noble-updates noble-backports\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n\nTypes: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble-security\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n' \
+            > /etc/apt/sources.list.d/armhf-ports.sources; \
+    fi \
     && apt-get update \
     && apt-get install -y --no-install-recommends \
         build-essential cmake ninja-build pkg-config python3 perl \
@@ -104,16 +106,19 @@ RUN mkdir /qt-build-target && cd /qt-build-target \
     && cmake --install . \
     && rm -rf /qt-build-target /qt-src
 
-# ── Stage 2: Final cross-compilation image ────────────────────────
-FROM ubuntu:24.04
+# ── Stage 3: Final cross-compilation image ────────────────────────
+FROM ubuntu:24.04 AS cross-compiler
 
 ENV DEBIAN_FRONTEND=noninteractive
 
-# armhf packages live on ports.ubuntu.com, not archive.ubuntu.com
+# On amd64: archive.ubuntu.com only serves amd64, so add ports for armhf.
+# On arm64: ports.ubuntu.com already serves both arm64 and armhf — no changes needed.
 RUN dpkg --add-architecture armhf \
-    && sed -i 's/^Types:/Architectures: amd64\nTypes:/' /etc/apt/sources.list.d/ubuntu.sources \
-    && printf 'Types: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble noble-updates noble-backports\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n\nTypes: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble-security\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n' \
-        > /etc/apt/sources.list.d/armhf-ports.sources \
+    && if [ "$(dpkg --print-architecture)" = "amd64" ]; then \
+        sed -i 's/^Types:/Architectures: amd64\nTypes:/' /etc/apt/sources.list.d/ubuntu.sources; \
+        printf 'Types: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble noble-updates noble-backports\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n\nTypes: deb\nURIs: http://ports.ubuntu.com/ubuntu-ports\nSuites: noble-security\nComponents: main universe multiverse restricted\nArchitectures: armhf\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\n' \
+            > /etc/apt/sources.list.d/armhf-ports.sources; \
+    fi \
     && apt-get update \
     && apt-get install -y --no-install-recommends \
         # ── Build tools ──

Makefile

@@ -0,0 +1,8 @@
+.PHONY: build clean
+
+build:
+	./docker-build.sh
+
+clean:
+	docker run --rm -v "$(CURDIR)/build-kobo:/build" ubuntu:24.04 rm -rf /build/* /build/.[!.]* 2>/dev/null; \
+	rm -rf build-kobo

docker-build.sh

@@ -13,8 +13,19 @@ HOST_UID=1000
 HOST_GID=1000
 NINJA_PACKAGE_TARGET="${NINJA_PACKAGE_TARGET:-kobo-package}"
 
+# Some arch detection
+HOST_ARCH="$(uname -m)"
+case "${HOST_ARCH}" in
+    x86_64)  DOCKER_PLATFORM="linux/amd64" ;;
+    aarch64|arm64) DOCKER_PLATFORM="linux/arm64" ;;
+    *) echo "WARNING: unknown architecture '${HOST_ARCH}', defaulting to linux/amd64" >&2
+       DOCKER_PLATFORM="linux/amd64" ;;
+esac
+echo "==> Host architecture: ${HOST_ARCH} → Docker platform: ${DOCKER_PLATFORM}"
+
 echo "==> Building Docker cross-compilation image …"
-docker build -t "${IMAGE_NAME}" -f "${SCRIPT_DIR}/Dockerfile.cross" "${SCRIPT_DIR}"
+docker build --platform "${DOCKER_PLATFORM}" \
+    -t "${IMAGE_NAME}" -f "${SCRIPT_DIR}/Dockerfile.cross" "${SCRIPT_DIR}"
 
 mkdir -p "${BUILD_DIR}"
 
@@ -29,6 +40,7 @@ if [[ -z "${KOBO_SYSROOT:-}" && -f "${ROOTFS_IMG}" ]]; then
         zstd -d "${ROOTFS_IMG}" -o "${BUILD_DIR}/rootfs.ext4" --force
         # Mount the ext4 image and copy contents (works without root via Docker)
         docker run --rm --privileged \
+            --platform "${DOCKER_PLATFORM}" \
             -v "${BUILD_DIR}:/work" \
             "${IMAGE_NAME}" \
             bash -c "
@@ -62,6 +74,7 @@ fi
 echo "==> Cross-compiling sKeets for Kobo …"
 echo "==> Packaging target: ${NINJA_PACKAGE_TARGET}"
 docker run --rm \
+    --platform "${DOCKER_PLATFORM}" \
     --user "${HOST_UID}:${HOST_GID}" \
     -v "${SCRIPT_DIR}:/src:ro" \
     -v "${BUILD_DIR}:/build" \