create the summary file. Based on work of Werner (OpenMoko)
ROOT_FLASH_SIZE = "256"
# extra jffs2 tweaks
-EXTRA_IMAGECMD_jffs2 = "--little-endian --eraseblock=0x4000 --pad -n"
+EXTRA_IMAGECMD_jffs2 = "--little-endian --eraseblock=0x20000 --pagesize=0x800 \
+ --no-cleanmarkers --pad -n ; sumtool --eraseblock=0x20000 --no-cleanmarkers \
+ --littleendian --pad \
+ -i ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.rootfs.jffs2 \
+ -o ${DEPLOY_DIR_IMAGE}/${IMAGE_NAME}.rootfs.jffs2.summary"
# build / upload tools
EXTRA_IMAGEDEPENDS += "sjf2410-linux-native dfu-util-native"