Add alternate grub setting for some systems

build_image

 #!/bin/bash
 
 # Copyright (c) 2009 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 build a bootable keyfob-based chromeos system image from within
 # a chromiumos setup. This assumes that all needed packages have been built into
 # the given target's root with binary packages turned on. This script will
 # build the Chrome OS image using only pre-built binary packages.
@@ skipping 431 matching lines @@
 # NOTE: These magic grub variables are a Chrome OS hack. They are not portable.
 
 menuentry "local image A" {
   linux $grubpartA/boot/vmlinuz quiet console=tty2 init=/sbin/init boot=local rootwait root=/dev/$linuxpartA ro noresume noswap i915.modeset=1 loglevel=1
 }
 
 menuentry "local image B" {
   linux $grubpartB/boot/vmlinuz quiet console=tty2 init=/sbin/init boot=local rootwait root=/dev/$linuxpartB ro noresume noswap i915.modeset=1 loglevel=1
 }
 
+menuentry "Alternate USB Boot" {
+  linux (hd0,3)/boot/vmlinuz quiet console=tty2 init=/sbin/init boot=local rootwait root=/dev/sdb3 ro noresume noswap i915.modeset=1 loglevel=1
+}
+
 EOF
 
 # FIXME: At the moment, we're working on signed images for x86 only. ARM will
 # support this before shipping, but at the moment they don't.
 if [[ "$ARCH" = "x86" ]]; then
   
   # Legacy BIOS will use the kernel in the rootfs (via syslinux), as will
   # standard EFI BIOS (via grub, from the EFI System Partition). Chrome OS BIOS
   # will use a separate signed kernel partition, which we'll create now.
   # FIXME: remove serial output, debugging messages
@@ skipping 99 matching lines @@
   echo "Recovery image created as $PRISTINE_IMAGE_NAME"
 fi
 if [ "$FLAGS_withdev" -eq "$FLAGS_TRUE" ]; then
   echo "Developer image created as $DEVELOPER_IMAGE_NAME"
 fi
 echo "To copy to USB keyfob, OUTSIDE the chroot, do something like:"
 echo "  ./image_to_usb.sh --from=${OUTSIDE_OUTPUT_DIR} --to=/dev/sdX"
 echo "To convert to VMWare image, OUTSIDE the chroot, do something like:"
 echo "  ./image_to_vmware.sh --from=${OUTSIDE_OUTPUT_DIR}"
 echo "from the scripts directory where you entered the chroot."