make_image: Fake vmlinuz_hd.vblock on ARM.

- This unbreaks the devserver's update server for ARM.
- This also unforks some of build_image.

BUG=None
TEST=Installed to tegra2_seaboard from USB without --skip_vblock,
     updated tegra2_seaboard.

Review URL: http://codereview.chromium.org/3493004

Change-Id: I6e66344de51609393407934f78aa20f49974efef

bin/cros_make_image_bootable

@@ -191,10 +191,8 @@ make_image_bootable() {
   # In original CL: http://codereview.chromium.org/2868044, this was done in
   # create_base_image(). However, it could break the build if it is a clean
   # build because vmlinuz_hd.vblock hasn't been created by build_kernel_image.sh
-  if [[ "${FLAGS_arch}" = "x86" ]]; then
-    sudo cp "${FLAGS_output_dir}/vmlinuz_hd.vblock" \
-            "${FLAGS_statefulfs_mountpoint}"
-  fi
+  sudo cp "${FLAGS_output_dir}/vmlinuz_hd.vblock" \
+          "${FLAGS_statefulfs_mountpoint}"
 
   # START_KERN_A is set by the first call to install the gpt.
   local koffset="$(partoffset ${image} 2)"

build_kernel_image.sh

@@ -226,6 +226,11 @@ elif [[ "${FLAGS_arch}" = "arm" ]]; then
   rm -f "${FLAGS_to}"
   dd if="${kernel_script_img}" of="${FLAGS_to}" bs=512 count="${script_size}"
   dd if="${kernel_image}" of="${FLAGS_to}" bs=512 seek="${script_size}"
+
+  # TODO: HACK: Until the kernel partition contains a signed image, create a
+  # phony hd.vblock to keep chromeos-install and cros_generate_update_payload
+  # working.
+  dd if="${FLAGS_to}" of="${FLAGS_hd_vblock}" bs=64K count=1
 else
   error "Unknown arch: ${FLAGS_arch}"
 fi