Merge lp:~dannf/maas-images/xgene-uboot-compressed-images into lp:maas-images

[dann frazier]

=== modified file 'bin/kh-xgene'
--- bin/kh-xgene	2014-06-18 16:32:32 +0000
+++ bin/kh-xgene	2016-10-14 14:08:55 +0000
@@ -4,6 +4,19 @@
 error() { echo "$@" 1>&2; }
 fail() { [ $# -eq 0 ] || error "$@"; exit 1; }
 
+compress_type() {
+    local file="$1"
+    magic="$(od -x -N2 $file | head -1 | cut -d' ' -f2)"
+    case $magic in
+        8b1f)
+            echo "gzip"
+            ;;
+        *)
+            echo "none"
+            ;;
+    esac
+}
+
 TEMP_D=$(mktemp -d "${0##*/}.XXXXXX") &&
 	trap cleanup EXIT || exit 1
 
@@ -16,9 +29,11 @@
 cp "$initrd" "${TEMP_D}/initrd" ||
 	fail "failed copy initrd '$initrd'"
 
-mkimage -A arm -O linux -T kernel  -C none -a 0x80000 -e 0x80000 \
+comp="$(compress_type ${TEMP_D}/kernel)"
+mkimage -A arm -O linux -T kernel  -C $comp -a 0x80000 -e 0x80000 \
     -n "kernel $info" -d "${TEMP_D}/kernel" "$kernel" ||
 	fail "failed mkimage for kernel";
-mkimage -A arm -O linux -T ramdisk -C gzip -a 0x0     -e 0x0 \
+comp="$(compress_type ${TEMP_D}/initrd)"
+mkimage -A arm -O linux -T ramdisk -C $comp -a 0x0     -e 0x0 \
     -n "ramdisk $info" -d "${TEMP_D}/initrd" "$initrd" ||
 	fail "failed mkimage for initrd";