board/common: Restore capability to create QEMU image from tarball

Previously, post-image.sh was able to create QEMU images from an
existing release tarball. This was useful when you wanted to test a
new bootloader build without having to wait for a full Infix build.

Restore this capability by adding a separate image target for it, and
then allow image-itb-qcow to source its input images from that instead
of a locally build squash+aux.

board/common/Config.in

@@ -5,6 +5,7 @@ source "$BR2_EXTERNAL_INFIX_PATH/board/common/image/image-itb-aux/Config.in"
 source "$BR2_EXTERNAL_INFIX_PATH/board/common/image/image-itb-qcow/Config.in"
 source "$BR2_EXTERNAL_INFIX_PATH/board/common/image/image-itb-gns3a/Config.in"
 source "$BR2_EXTERNAL_INFIX_PATH/board/common/image/image-itb-rauc/Config.in"
+source "$BR2_EXTERNAL_INFIX_PATH/board/common/image/image-itb-dl-release/Config.in"
 source "$BR2_EXTERNAL_INFIX_PATH/board/common/image/image-readme/Config.in"
 
 endmenu

board/common/image/image-itb-dl-release/Config.in

@@ -0,0 +1,15 @@
+menuconfig IMAGE_ITB_DL_RELEASE
+	bool "Download existing release"
+	depends on !BR2_TARGET_ROOTFS_SQUASHFS
+	help
+	  This is primarily used by target specific builds, where the
+	  bootloader artifact needs to be combined with an existing
+	  Infix image, to create a full disk image that can be
+	  provisioned to an SD-card or eMMC.
+
+config IMAGE_ITB_DL_RELEASE_URL
+	string "URL"
+	depends on IMAGE_ITB_DL_RELEASE
+	default "https://github.com/kernelkit/infix/releases/download/latest/infix-${BR2_ARCH}.tar.gz"
+	help
+	  URL to release tarball.

board/common/image/image-itb-dl-release/generate.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+set -e
+
+squash="${BINARIES_DIR}"/rootfs.squashfs
+aux="${BINARIES_DIR}"/aux.ext4
+
+[ -f "${squash}" ] && [ -f "${aux}" ] && exit 0
+
+archive="${WORKDIR}/$(basename ${URL})"
+[ -f "${archive}" ] || wget -O"${archive}" "${URL}"
+
+echo "Unpacking..."
+tar -xa --strip-components=1 -C "${BINARIES_DIR}" -f "${archive}"
+
+auxsize=$(stat -c %s "${aux}")
+if [ "${auxsize}" -gt $((8 << 20)) ]; then
+    # In older releases, 16M aux.ext4 images were generated. In order
+    # to keep the image-itb-qcow logic simpler, trim it 8M, which we
+    # always generate nowadays.
+    echo "WARNING: Auxiliary partition is unexpectedly large. Resizing..."
+    resize2fs "${aux}" 8M
+    truncate -s 8M "${aux}"
+    tune2fs -l "${aux}"
+fi

board/common/image/image-itb-dl-release/image-itb-dl-release.mk

@@ -0,0 +1,9 @@
+################################################################################
+#
+# image-itb-dl-release
+#
+################################################################################
+
+IMAGE_ITB_DL_RELEASE_CONFIG_VARS := URL
+
+$(eval $(ix-image))

board/common/image/image-itb-qcow/Config.in

@@ -1,8 +1,6 @@
 menuconfig IMAGE_ITB_QCOW
 	bool "QEMU disk image (ITB)"
-	default y
-	select IMAGE_ITB_ROOTFS
-	select IMAGE_ITB_AUX
+	depends on (IMAGE_ITB_ROOTFS && IMAGE_ITB_AUX) || IMAGE_ITB_DL_RELEASE
 	select BR2_PACKAGE_HOST_GENIMAGE
 	help
 	  Compose a full disk image with redundant Linux OS partitions,
@@ -68,13 +66,3 @@ config IMAGE_ITB_QCOW_BOOT_OFFSET
 	  Offset at which the bootloader partition is placed. Remember
 	  to make sure that the GPT still fits at the start of the
 	  image.
-
-config IMAGE_ITB_QCOW_RELEASE_URL
-	string "Infix URL"
-	depends on IMAGE_ITB_QCOW
-	depends on !BR2_TARGET_ROOTFS_SQUASHFS
-	default "https://github.com/kernelkit/infix/releases/download/latest/infix-${BR2_ARCH}.tar.gz"
-	help
-	  In situations where Infix itself is not being built, but a
-	  disk image is, i.e. when building a bootloader: place this
-	  Infix release in the primary and secondary partitions.

board/common/image/image-itb-qcow/image-itb-qcow.mk

@@ -4,7 +4,12 @@
 #
 ################################################################################
 
-IMAGE_ITB_QCOW_DEPENDENCIES := host-genimage image-itb-rootfs image-itb-aux
+# We can source the rootfs+aux from a local build, or from a
+# downloaded release; so adjust our dependencies accordingly.
+IMAGE_ITB_QCOW_SRC-$(IMAGE_ITB_ROOTFS)     := image-itb-rootfs image-itb-aux
+IMAGE_ITB_QCOW_SRC-$(IMAGE_ITB_DL_RELEASE) := image-itb-dl-release
+
+IMAGE_ITB_QCOW_DEPENDENCIES := host-genimage $(IMAGE_ITB_QCOW_SRC-y)
 IMAGE_ITB_QCOW_CONFIG_VARS := BOOT_DATA BOOT_OFFSET SIZE
 
 $(eval $(ix-image))