AU: when generating payload, don't patch kernel by default

cros_generate_update_payload

 #!/bin/bash
 
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Script to generate a Chromium OS update for use by the update engine.
 # If a source .bin is specified, the update is assumed to be a delta update.
 
 # Load common constants.  This should be the first executable line.
@@ skipping 82 matching lines @@
 }
 
 # We should be in the chroot.
 assert_inside_chroot
 
 DEFINE_string image "" "The image that should be sent to clients."
 DEFINE_string src_image "" "Optional: a source image. If specified, this makes\
  a delta update."
 DEFINE_boolean old_style "$FLAGS_TRUE" "Generate an old-style .gz full update."
 DEFINE_string output "" "Output file"
+DEFINE_boolean patch_kernel "$FLAGS_FALSE" "Whether or not to patch the kernel \
+with the patch from the stateful partition (default: false)"
 
 # Parse command line
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 
 set -e
 
 locate_gpt
 
 DELTA=$FLAGS_TRUE
@@ skipping 11 matching lines @@
 
 if [ "$DELTA" -eq "$FLAGS_TRUE" ]; then
   echo "Generating a delta update"
   
   # Sanity check that the real generator exists:
   GENERATOR="$(dirname "$0")/../platform/update_engine/delta_generator"
   [ -x "$GENERATOR" ] || die "$GENERATOR doesn't exist, or isn't executable"
 
   trap cleanup INT TERM EXIT
   SRC_KERNEL=$(extract_partition_to_temp_file "$FLAGS_src_image" 2)
-  patch_kernel "$FLAGS_src_image" "$SRC_KERNEL"
+  if [ "$FLAGS_patch_kernel" -eq "$FLAGS_TRUE" ]; then
+    patch_kernel "$FLAGS_src_image" "$SRC_KERNEL"
+  fi
   SRC_ROOT=$(extract_partition_to_temp_file "$FLAGS_src_image" 3)
 
   echo md5sum of src kernel:
   md5sum "$SRC_KERNEL"
   echo md5sum of src root:
   md5sum "$SRC_ROOT"
   
   DST_KERNEL=$(extract_partition_to_temp_file "$FLAGS_image" 2)
-  patch_kernel "$FLAGS_image" "$DST_KERNEL"
+  if [ "$FLAGS_patch_kernel" -eq "$FLAGS_TRUE" ]; then
+    patch_kernel "$FLAGS_image" "$DST_KERNEL"
+  fi
   DST_ROOT=$(extract_partition_to_temp_file "$FLAGS_image" 3)
   
   SRC_MNT=$(mktemp -d /tmp/src_root.XXXXXX)
   sudo mount -o loop,ro "$SRC_ROOT" "$SRC_MNT"
 
   DST_MNT=$(mktemp -d /tmp/src_root.XXXXXX)
   sudo mount -o loop,ro "$DST_ROOT" "$DST_MNT"
   
   sudo "$GENERATOR" \
       -new_dir "$DST_MNT" -new_image "$DST_ROOT" -new_kernel "$DST_KERNEL" \
       -old_dir "$SRC_MNT" -old_image "$SRC_ROOT" -old_kernel "$SRC_KERNEL" \
       -out_file "$FLAGS_output"
   
   trap - INT TERM EXIT
   cleanup noexit
   echo "Done generating delta."
 else
   echo "Generating full update"
   
   trap cleanup INT TERM EXIT
   DST_KERNEL=$(extract_partition_to_temp_file "$FLAGS_image" 2)
-  patch_kernel "$FLAGS_image" "$DST_KERNEL"
+  if [ "$FLAGS_patch_kernel" -eq "$FLAGS_TRUE" ]; then
+    patch_kernel "$FLAGS_image" "$DST_KERNEL"
+  fi
   DST_ROOT=$(extract_partition_to_temp_file "$FLAGS_image" 3)
   
   GENERATOR="$(dirname "$0")/mk_memento_images.sh"
 
   CROS_GENERATE_UPDATE_PAYLOAD_CALLED=1 "$GENERATOR" "$DST_KERNEL" "$DST_ROOT"
   mv "$(dirname "$DST_KERNEL")/update.gz" "$FLAGS_output"
   
   trap - INT TERM EXIT
   cleanup noexit
   echo "Done generating full update."
 fi