[atheros] Implement a preliminary combined image format.

[openwrt.git] / scripts / combined-image.sh

diff --git a/scripts/combined-image.sh b/scripts/combined-image.sh
new file mode 100644 (file)
index 0000000..eecd3d7
--- /dev/null
+++ b/scripts/combined-image.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+BLKSZ=65536
+
+[ -f "$1" -a -f "$2" ] || {
+       echo "Usage: $0 <kernel image> <rootfs image> [output file]"
+       exit 1
+}
+
+# Make sure provided images are 64k aligned.
+kern=$(tempfile)
+root=$(tempfile)
+dd if="$1" of="$kern" bs=$BLKSZ conv=sync 2>/dev/null
+dd if="$2" of="$root" bs=$BLKSZ conv=sync 2>/dev/null
+
+# Calculate md5sum over combined kernel and rootfs image.
+md5=$(cat "$kern" "$root" | md5sum -)
+
+# Write image header followed by kernel and rootfs image.
+# The header is padded to 64k, format is:
+#  CI               magic word ("Combined Image")
+#  <kernel length>  length of kernel encoded as zero padded 8 digit hex
+#  <rootfs length>  length of rootfs encoded as zero padded 8 digit hex
+#  <md5sum>         checksum of the combined kernel and rootfs image
+( printf "CI%08x%08x%32s" \
+       $(stat -c "%s" "$kern") $(stat -c "%s" "$root") "${md5%% *}" | \
+       dd bs=$BLKSZ conv=sync;
+  cat "$kern" "$root"
+) > ${3:-openwrt-combined.img} 2>/dev/null
+
+# Clean up.
+rm -f "$kern" "$root"