Bug#831003: support gzip'd kernel image

[dann frazier <dannf@debian.org>]

Package: flash-kernel
Version: 3.67
Tags: patch

flash-kernel currently always sets the compression type to "none" when
generating uImages. However, if the source vmlinuz file is gzip'd - as
is the case if you build the "Image.gz" kernel target - this will
prevent U-Boot from being able to boot it[1]. If the uImage is
generated with a compression type of "gzip", then it boots fine.

The attached patch checks the source image type and sets the
compression setting appropriately.

[1] At least, this is true on APM Mustang systems

diff -urpN flash-kernel-3.67/debian/changelog flash-kernel-3.68/debian/changelog
--- flash-kernel-3.67/debian/changelog	2016-06-20 00:20:31.000000000 -0600
+++ flash-kernel-3.68/debian/changelog	2016-07-13 09:33:53.714642651 -0600
@@ -1,3 +1,9 @@
+flash-kernel (3.68) UNRELEASED; urgency=medium
+
+  * Add support for gzip-compressed kernel images
+
+ -- dann frazier <dannf@debian.org>  Wed, 13 Jul 2016 09:22:49 -0600
+
 flash-kernel (3.67) unstable; urgency=medium
 
   [ Vagrant Cascadian ]
diff -urpN flash-kernel-3.67/functions flash-kernel-3.68/functions
--- flash-kernel-3.67/functions	2016-04-01 21:01:45.000000000 -0600
+++ flash-kernel-3.68/functions	2016-07-13 09:25:43.520547829 -0600
@@ -409,15 +409,31 @@ get_kernel_cmdline_defaults() {
 	echo "$LINUX_KERNEL_CMDLINE_DEFAULTS"
 }
 
+compress_type() {
+    local file="$1"
+    magic="$(od -x -N2 $file | head -1 | cut -d' ' -f2)"
+    case $magic in
+	8b1f)
+	    echo "gzip"
+	    ;;
+	*)
+	    echo "none"
+	    ;;
+    esac
+}
+
 mkimage_kernel() {
 	local kaddr="$1"
 	local epoint="$2"
 	local kdesc="$3"
 	local kdata="$4"
 	local uimage="$5"
+	local comp
+
+	comp="$(compress_type $kdata)"
 
 	printf "Generating kernel u-boot image... " >&2
-	mkimage -A arm -O linux -T kernel -C none -a "$kaddr" -e "$epoint" \
+	mkimage -A arm -O linux -T kernel -C $comp -a "$kaddr" -e "$epoint" \
 		-n "$kdesc" -d "$kdata" "$uimage" >&2 1>/dev/null
 	echo "done." >&2
 }
diff -urpN flash-kernel-3.67/test_functions flash-kernel-3.68/test_functions
--- flash-kernel-3.67/test_functions	2016-02-14 21:01:43.000000000 -0700
+++ flash-kernel-3.68/test_functions	2016-07-13 09:28:35.812630206 -0600
@@ -569,23 +569,40 @@ test_set_machine_id() {
 }
 add_test test_set_machine_id
 
-test_mkimage_kernel() {
+_test_mkimage_kernel() {
+    local kdata="$1"
+    local expected="$2"
     (
         mkimage() {
             saved_args="$@"
         }
         . "$functions"
         saved_args=""
-        mkimage_kernel "0xdeadbeef" "0xbaddcafe" "desc" "input" "output" 2>/dev/null
-        expected="-A arm -O linux -T kernel -C none -a 0xdeadbeef -e 0xbaddcafe -n desc -d input output"
+        mkimage_kernel "0xdeadbeef" "0xbaddcafe" "desc" "$kdata" "output" 2>/dev/null
         if [ "$expected" != "$saved_args" ]; then
             echo "Expected mkimage_kernel to be called with \"$expected\" but it was called with \"$saved_args\"" >&2
-            exit 1
+            return 1
         fi
     )
 }
+
+test_mkimage_kernel() {
+    local kdata="/dev/zero"
+    local expected="-A arm -O linux -T kernel -C none -a 0xdeadbeef -e 0xbaddcafe -n desc -d $kdata output"
+    _test_mkimage_kernel "$kdata" "$expected" || exit 1
+}
 add_test test_mkimage_kernel
 
+test_mkimage_kernel_gzip() {
+    local kdata="$(mktemp)"
+    gzip < /dev/null > "$kdata"
+
+    local expected="-A arm -O linux -T kernel -C gzip -a 0xdeadbeef -e 0xbaddcafe -n desc -d $kdata output"
+    _test_mkimage_kernel "$kdata" "$expected" || exit 1
+    rm -f "$kdata"
+}
+add_test test_mkimage_kernel_gzip
+ 
 test_mkimage_initrd() {
     (
         mkimage() {