fix: complete ARM64 RPi build pipeline

- fetch-components.sh: download ARM64 KubeSolo binary (kubesolo-arm64)
- inject-kubesolo.sh: use arch-specific binaries for KubeSolo, cloud-init,
  and update agent; detect KVER from custom kernel when rootfs has none;
  cross-arch module resolution via find fallback when modprobe fails
- create-rpi-image.sh: kpartx support for Docker container builds
- Makefile: rootfs-arm64 depends on build-cross, includes pack-initramfs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Makefile

@@ -79,11 +79,13 @@ kernel-arm64:
 	@echo "==> Building ARM64 kernel for Raspberry Pi..."
 	$(BUILD_DIR)/scripts/build-kernel-arm64.sh
 
-rootfs-arm64:
+rootfs-arm64: build-cross
 	@echo "==> Preparing ARM64 rootfs..."
 	TARGET_ARCH=arm64 $(BUILD_DIR)/scripts/fetch-components.sh
 	TARGET_ARCH=arm64 $(BUILD_DIR)/scripts/extract-core.sh
 	TARGET_ARCH=arm64 $(BUILD_DIR)/scripts/inject-kubesolo.sh
+	@echo "==> Packing ARM64 initramfs..."
+	$(BUILD_DIR)/scripts/pack-initramfs.sh
 
 rpi-image: rootfs-arm64 kernel-arm64
 	@echo "==> Creating Raspberry Pi SD card image..."

build/scripts/create-rpi-image.sh

@@ -83,9 +83,38 @@ type=0FC63DAF-8483-4772-8E79-3D69D8477DE4, name="Data"
 EOF
 
 # --- Set up loop device ---
-LOOP=$(losetup --show -fP "$IMG_OUTPUT")
+LOOP=$(losetup --show -f "$IMG_OUTPUT")
 echo "==> Loop device: $LOOP"
 
+# Use kpartx for reliable partition device nodes (works in Docker/containers)
+USE_KPARTX=false
+if [ ! -b "${LOOP}p1" ]; then
+    if command -v kpartx >/dev/null 2>&1; then
+        kpartx -a "$LOOP"
+        USE_KPARTX=true
+        sleep 1
+        LOOP_NAME=$(basename "$LOOP")
+        P1="/dev/mapper/${LOOP_NAME}p1"
+        P2="/dev/mapper/${LOOP_NAME}p2"
+        P3="/dev/mapper/${LOOP_NAME}p3"
+        P4="/dev/mapper/${LOOP_NAME}p4"
+    else
+        # Retry with -P flag
+        losetup -d "$LOOP"
+        LOOP=$(losetup --show -fP "$IMG_OUTPUT")
+        sleep 1
+        P1="${LOOP}p1"
+        P2="${LOOP}p2"
+        P3="${LOOP}p3"
+        P4="${LOOP}p4"
+    fi
+else
+    P1="${LOOP}p1"
+    P2="${LOOP}p2"
+    P3="${LOOP}p3"
+    P4="${LOOP}p4"
+fi
+
 MNT_CTL=$(mktemp -d)
 MNT_BOOTA=$(mktemp -d)
 MNT_BOOTB=$(mktemp -d)
@@ -96,22 +125,25 @@ cleanup() {
     umount "$MNT_BOOTA" 2>/dev/null || true
     umount "$MNT_BOOTB" 2>/dev/null || true
     umount "$MNT_DATA" 2>/dev/null || true
+    if [ "$USE_KPARTX" = true ]; then
+        kpartx -d "$LOOP" 2>/dev/null || true
+    fi
     losetup -d "$LOOP" 2>/dev/null || true
     rm -rf "$MNT_CTL" "$MNT_BOOTA" "$MNT_BOOTB" "$MNT_DATA" 2>/dev/null || true
 }
 trap cleanup EXIT
 
 # --- Format partitions ---
-mkfs.vfat -F 32 -n KSOLOCTL "${LOOP}p1"
-mkfs.vfat -F 32 -n KSOLOA "${LOOP}p2"
-mkfs.vfat -F 32 -n KSOLOB "${LOOP}p3"
-mkfs.ext4 -q -L KSOLODATA "${LOOP}p4"
+mkfs.vfat -F 32 -n KSOLOCTL "$P1"
+mkfs.vfat -F 32 -n KSOLOA "$P2"
+mkfs.vfat -F 32 -n KSOLOB "$P3"
+mkfs.ext4 -q -L KSOLODATA "$P4"
 
 # --- Mount all partitions ---
-mount "${LOOP}p1" "$MNT_CTL"
-mount "${LOOP}p2" "$MNT_BOOTA"
-mount "${LOOP}p3" "$MNT_BOOTB"
-mount "${LOOP}p4" "$MNT_DATA"
+mount "$P1" "$MNT_CTL"
+mount "$P2" "$MNT_BOOTA"
+mount "$P3" "$MNT_BOOTB"
+mount "$P4" "$MNT_DATA"
 
 # --- Boot Control Partition (KSOLOCTL) ---
 echo "    Writing autoboot.txt..."

build/scripts/fetch-components.sh

@@ -51,6 +51,39 @@ if [ "$FETCH_ARCH" = "arm64" ]; then
     echo "==> Fetching RPi firmware..."
     "$SCRIPT_DIR/fetch-rpi-firmware.sh"
 
+    # Download ARM64 KubeSolo binary
+    KUBESOLO_VERSION="${KUBESOLO_VERSION:-v1.1.0}"
+    KUBESOLO_BIN_ARM64="$CACHE_DIR/kubesolo-arm64"
+    if [ -f "$KUBESOLO_BIN_ARM64" ]; then
+        echo "==> KubeSolo ARM64 binary already cached: $KUBESOLO_BIN_ARM64"
+    else
+        echo "==> Downloading KubeSolo ${KUBESOLO_VERSION} (arm64)..."
+        BIN_URL="https://github.com/portainer/kubesolo/releases/download/${KUBESOLO_VERSION}/kubesolo-${KUBESOLO_VERSION}-linux-arm64-musl.tar.gz"
+        BIN_URL_FALLBACK="https://github.com/portainer/kubesolo/releases/download/${KUBESOLO_VERSION}/kubesolo-${KUBESOLO_VERSION}-linux-arm64.tar.gz"
+        TEMP_DIR=$(mktemp -d)
+        echo "    URL: $BIN_URL"
+        if curl -fSL "$BIN_URL" -o "$TEMP_DIR/kubesolo.tar.gz" 2>/dev/null; then
+            echo "    Downloaded musl variant (arm64)"
+        elif curl -fSL "$BIN_URL_FALLBACK" -o "$TEMP_DIR/kubesolo.tar.gz" 2>/dev/null; then
+            echo "    Downloaded glibc variant (arm64 fallback)"
+        else
+            echo "ERROR: Failed to download KubeSolo ARM64 from GitHub."
+            rm -rf "$TEMP_DIR"
+            exit 1
+        fi
+        tar -xzf "$TEMP_DIR/kubesolo.tar.gz" -C "$TEMP_DIR"
+        FOUND_BIN=$(find "$TEMP_DIR" -name "kubesolo" -type f ! -name "*.tar.gz" | head -1)
+        if [ -z "$FOUND_BIN" ]; then
+            echo "ERROR: Could not find kubesolo binary in extracted archive"
+            rm -rf "$TEMP_DIR"
+            exit 1
+        fi
+        cp "$FOUND_BIN" "$KUBESOLO_BIN_ARM64"
+        chmod +x "$KUBESOLO_BIN_ARM64"
+        rm -rf "$TEMP_DIR"
+        echo "==> KubeSolo ARM64 binary: $KUBESOLO_BIN_ARM64 ($(du -h "$KUBESOLO_BIN_ARM64" | cut -f1))"
+    fi
+
     # Skip x86_64 ISO and TCZ downloads for ARM64
     echo ""
     echo "==> ARM64 fetch complete."

build/scripts/inject-kubesolo.sh

@@ -25,7 +25,11 @@ if [ ! -d "$ROOTFS" ]; then
     exit 1
 fi
 
-KUBESOLO_BIN="$CACHE_DIR/kubesolo"
+if [ "$INJECT_ARCH" = "arm64" ]; then
+    KUBESOLO_BIN="$CACHE_DIR/kubesolo-arm64"
+else
+    KUBESOLO_BIN="$CACHE_DIR/kubesolo"
+fi
 if [ ! -f "$KUBESOLO_BIN" ]; then
     echo "ERROR: KubeSolo binary not found: $KUBESOLO_BIN"
     echo "See fetch-components.sh output for instructions."
@@ -78,23 +82,27 @@ for lib in network.sh health.sh; do
 done
 
 # Cloud-init binary (Go, built separately)
-CLOUDINIT_BIN="$CACHE_DIR/kubesolo-cloudinit"
+# Try arch-specific binary first, then fall back to generic
+CLOUDINIT_BIN="$CACHE_DIR/kubesolo-cloudinit-linux-$INJECT_ARCH"
+[ ! -f "$CLOUDINIT_BIN" ] && CLOUDINIT_BIN="$CACHE_DIR/kubesolo-cloudinit"
 if [ -f "$CLOUDINIT_BIN" ]; then
     cp "$CLOUDINIT_BIN" "$ROOTFS/usr/lib/kubesolo-os/kubesolo-cloudinit"
     chmod +x "$ROOTFS/usr/lib/kubesolo-os/kubesolo-cloudinit"
     echo "    Installed cloud-init binary ($(du -h "$CLOUDINIT_BIN" | cut -f1))"
 else
-    echo "    WARN: Cloud-init binary not found (run 'make build-cloudinit' to build)"
+    echo "    WARN: Cloud-init binary not found (run 'make build-cloudinit' or 'make build-cross' to build)"
 fi
 
 # Update agent binary (Go, built separately)
-UPDATE_BIN="$CACHE_DIR/kubesolo-update"
+# Try arch-specific binary first, then fall back to generic
+UPDATE_BIN="$CACHE_DIR/kubesolo-update-linux-$INJECT_ARCH"
+[ ! -f "$UPDATE_BIN" ] && UPDATE_BIN="$CACHE_DIR/kubesolo-update"
 if [ -f "$UPDATE_BIN" ]; then
     cp "$UPDATE_BIN" "$ROOTFS/usr/lib/kubesolo-os/kubesolo-update"
     chmod +x "$ROOTFS/usr/lib/kubesolo-os/kubesolo-update"
     echo "    Installed update agent ($(du -h "$UPDATE_BIN" | cut -f1))"
 else
-    echo "    WARN: Update agent not found (run 'make build-update-agent' to build)"
+    echo "    WARN: Update agent not found (run 'make build-update-agent' or 'make build-cross' to build)"
 fi
 
 # --- 3. Custom kernel or TCZ kernel modules ---
@@ -115,8 +123,16 @@ for d in "$ROOTFS"/lib/modules/*/; do
     [ -d "$d" ] && KVER="$(basename "$d")" && break
 done
 
+# Fallback: detect from custom kernel modules directory
+if [ -z "$KVER" ] && [ -d "$CUSTOM_MODULES/lib/modules" ]; then
+    for d in "$CUSTOM_MODULES"/lib/modules/*/; do
+        [ -d "$d" ] && KVER="$(basename "$d")" && break
+    done
+    echo "    Detected kernel version from custom kernel: $KVER"
+fi
+
 if [ -z "$KVER" ]; then
-    echo "    WARN: Could not detect kernel version from rootfs"
+    echo "    WARN: Could not detect kernel version from rootfs or custom kernel"
 fi
 
 echo "    Kernel version: $KVER"
@@ -145,24 +161,49 @@ if [ -f "$CUSTOM_VMLINUZ" ] && [ -d "$CUSTOM_MODULES/lib/modules/$KVER" ]; then
         [ -f "$CUSTOM_MOD_DIR/$f" ] && cp "$CUSTOM_MOD_DIR/$f" "$ROOTFS/lib/modules/$KVER/"
     done
 
-    # Use modprobe --show-depends to resolve each module + its transitive deps
+    # Resolve and install modules from modules.list + transitive deps
     if [ "$INJECT_ARCH" = "arm64" ]; then
         MODULES_LIST="$PROJECT_ROOT/build/config/modules-arm64.list"
     else
         MODULES_LIST="$PROJECT_ROOT/build/config/modules.list"
     fi
     NEEDED_MODS=$(mktemp)
+
+    # Try modprobe first (works for same-arch builds)
+    MODPROBE_WORKS=true
+    FIRST_MOD=$(grep -v '^#' "$MODULES_LIST" | grep -v '^$' | head -1 | xargs)
+    if ! modprobe -S "$KVER" -d "$CUSTOM_MODULES" --show-depends "$FIRST_MOD" >/dev/null 2>&1; then
+        MODPROBE_WORKS=false
+        echo "    modprobe cannot resolve modules (cross-arch build) — using find fallback"
+    fi
+
     while IFS= read -r mod; do
         # Skip comments and blank lines
         case "$mod" in \#*|"") continue ;; esac
         mod=$(echo "$mod" | xargs)  # trim whitespace
         [ -z "$mod" ] && continue
 
-        # modprobe -S <ver> -d <root> --show-depends <module> lists all deps in load order
-        # Output format: "insmod /path/to/module.ko" — extract path with awk
-        modprobe -S "$KVER" -d "$CUSTOM_MODULES" --show-depends "$mod" 2>/dev/null \
-            | awk '/^insmod/{print $2}' >> "$NEEDED_MODS" \
-            || echo "    WARN: modprobe could not resolve: $mod"
+        if [ "$MODPROBE_WORKS" = true ]; then
+            # modprobe -S <ver> -d <root> --show-depends <module> lists all deps in load order
+            modprobe -S "$KVER" -d "$CUSTOM_MODULES" --show-depends "$mod" 2>/dev/null \
+                | awk '/^insmod/{print $2}' >> "$NEEDED_MODS" \
+                || echo "    WARN: modprobe could not resolve: $mod"
+        else
+            # Cross-arch fallback: find module by name in kernel tree
+            found=$(find "$CUSTOM_MOD_DIR/kernel" -name "${mod}.ko" -o -name "${mod}.ko.xz" -o -name "${mod}.ko.gz" -o -name "${mod}.ko.zst" 2>/dev/null | head -1)
+            if [ -n "$found" ]; then
+                echo "$found" >> "$NEEDED_MODS"
+            else
+                # Try replacing hyphens with underscores and vice versa
+                mod_alt=$(echo "$mod" | tr '-' '_')
+                found=$(find "$CUSTOM_MOD_DIR/kernel" -name "${mod_alt}.ko" -o -name "${mod_alt}.ko.xz" -o -name "${mod_alt}.ko.gz" -o -name "${mod_alt}.ko.zst" 2>/dev/null | head -1)
+                if [ -n "$found" ]; then
+                    echo "$found" >> "$NEEDED_MODS"
+                else
+                    echo "    WARN: could not find module: $mod"
+                fi
+            fi
+        fi
     done < "$MODULES_LIST"
 
     # Deduplicate and copy each needed module