read kernel id from a file, make compression optional

meta-citadel/classes/citadel-image.bbclass

@@ -4,14 +4,12 @@ DEPENDS_append = " citadel-image-native mtools-native cryptsetup-native"
 # Block size must be 4096 or dm-verity won't work
 EXTRA_IMAGECMD_ext2 = "-i 4096 -b 4096"
 IMAGE_FSTYPES = "ext2"
+IMAGE_OVERHEAD_FACTOR = "1.1"
 
 inherit image
 
 CITADEL_IMAGE_CHANNEL ??= "dev"
-
-kernel_id() {
-    sha256sum ${DEPLOY_DIR_IMAGE}/bzImage-intel-corei7-64.bin | cut -d' ' -f1
-}
+CITADEL_IMAGE_COMPRESS ??= "true"
 
 do_citadel_mkimage() {
     cat > ${B}/mkimage.conf << EOF
@@ -20,12 +18,13 @@ channel = "${CITADEL_IMAGE_CHANNEL}"
 version = ${CITADEL_IMAGE_VERSION}
 timestamp = "${DATETIME}"
 source = "${IMGDEPLOYDIR}/${IMAGE_LINK_NAME}.ext2"
+compress = ${CITADEL_IMAGE_COMPRESS}
 EOF
 
     ver=$(printf "%03d" ${CITADEL_IMAGE_VERSION})
 
     if [ "${CITADEL_IMAGE_TYPE}" = "kernel" ]; then
-        KERNEL_ID=$(kernel_id)
+        KERNEL_ID=$(cat ${DEPLOY_DIR_IMAGE}/kernel.id)
         echo "kernel-version = \"${CITADEL_KERNEL_VERSION}\"" >> ${B}/mkimage.conf
         echo "kernel-id = \"${KERNEL_ID}\"" >> ${B}/mkimage.conf
         fname="citadel-kernel-${CITADEL_KERNEL_VERSION}-${CITADEL_IMAGE_CHANNEL}-${ver}.img"