build_image, build_kernel_image, update_bootloaders: fix up rootfs_verification

create_legacy_bootloader_templates.sh

 #!/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.
 
 # Helper script that generates the signed kernel image
 
 . "$(dirname "$0")/common.sh"
 
@@ skipping 81 matching lines @@
 
 # chromeos-hd.A / chromeos-vhd.A
 include /syslinux/root.A.cfg
 
 # chromeos-hd.B / chromeos-vhd.B
 include /syslinux/root.B.cfg
 EOF
   info "Emitted ${SYSLINUX_DIR}/syslinux.cfg"
 
   if [[ ${FLAGS_enable_rootfs_verification} -eq ${FLAGS_TRUE} ]]; then
-    # To change the active target, only this file needs to change.
-    cat <<EOF | sudo dd of="${SYSLINUX_DIR}/default.cfg" 2>/dev/null
-DEFAULT chromeos-vusb.A
-EOF
-  else
-      cat <<EOF | sudo dd of="${SYSLINUX_DIR}/default.cfg" 2>/dev/null
+    # TODO(wad, tgao) enable usb vbooting with initramfs or device probing.
+    warn "USB booting will not use rootfs verification."
+  fi
+  # To change the active target, only this file needs to change.
+  cat <<EOF | sudo dd of="${SYSLINUX_DIR}/default.cfg" 2>/dev/null
 DEFAULT chromeos-usb.A
 EOF
-  fi
   info "Emitted ${SYSLINUX_DIR}/default.cfg"
 
   cat <<EOF | sudo dd of="${SYSLINUX_DIR}/usb.A.cfg" 2>/dev/null
 label chromeos-usb.A
   menu label chromeos-usb.A
   kernel vmlinuz.A
   append ${common_args} root=${FLAGS_usb_disk} i915.modeset=1 cros_legacy
 
 label chromeos-vusb.A
   menu label chromeos-vusb.A
@@ skipping 74 matching lines @@
 EOF
   if [[ ${FLAGS_enable_rootfs_verification} -eq ${FLAGS_TRUE} ]]; then
     sudo sed -i -e 's/^set default=.*/set default=2/' \
        "${FLAGS_to}/efi/boot/grub.cfg"
   fi
   info "Emitted ${FLAGS_to}/efi/boot/grub.cfg"
   exit 0
 fi
 
 info "The target platform does not use bootloader templates."