Use new grub2 variables to boot from the device with the bootloader

src/scripts/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 349 matching lines @@
 if [ -z "$ESP_LOOP_DEV" ] ; then
   echo "No free loop device.  Free up a loop device or reboot.  exiting. "
   exit 1
 fi
 mkdir -p "${ESP_DIR}"
 sudo losetup "${ESP_LOOP_DEV}" "${ESP_IMG}"
 sudo mount "${ESP_LOOP_DEV}" "${ESP_DIR}"
 sudo mkdir -p "${ESP_DIR}/efi/boot"
 sudo grub-mkimage -p /efi/boot -o "${ESP_DIR}/efi/boot/bootx64.efi" \
   part_gpt fat ext2 normal boot sh chain configfile linux
-sudo cp "${ROOT_FS_DIR}/boot/vmlinuz" "${ESP_DIR}/efi/boot/vmlinuz"
-cat <<EOF | sudo dd of="${ESP_DIR}/efi/boot/grub.cfg"
+cat <<'EOF' | sudo dd of="${ESP_DIR}/efi/boot/grub.cfg"
+set default=0
 set timeout=2
-set default=0
 
-menuentry "boot from disk" {
-  linux /efi/boot/vmlinuz quiet console=tty2 init=/sbin/init boot=local rootwait root=/dev/sda3 ro noresume noswap i915.modeset=1 loglevel=1
+# 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 "boot from disk with serial debug" {
-  linux /efi/boot/vmlinuz earlyprintk=serial,ttyS0,115200 console=ttyS0,115200 init=/sbin/init boot=local rootwait root=/dev/sda3 ro noresume noswap i915.modeset=1 loglevel=7
-}
-
-menuentry "boot from usb" {
-  linux /efi/boot/vmlinuz quiet console=tty2 init=/sbin/init boot=local rootwait root=/dev/sdb3 ro noresume noswap i915.modeset=1 loglevel=1
-}
-
-menuentry "boot from usb with serial debug" {
-  linux /efi/boot/vmlinuz earlyprintk=serial,ttyS0,115200 console=ttyS0,115200 init=/sbin/init boot=local rootwait root=/dev/sdb3 ro noresume noswap i915.modeset=1 loglevel=7
+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
 }
 
 EOF
 
 # By default, dev mode should be activated for either development builds or
 # test builds.
 if [[ $FLAGS_withdev -eq $FLAGS_TRUE ]] ||\
     [[ $FLAGS_withtest -eq $FLAGS_TRUE ]]; then
   sudo touch "$ROOT_FS_DIR/root/.dev_mode"
 
@@ skipping 37 matching lines @@
 
 OUTSIDE_OUTPUT_DIR="../build/images/${FLAGS_board}/${IMAGE_SUBDIR}"
 echo "Done.  Image created in ${OUTPUT_DIR}"
 echo "To copy to USB keyfob, OUTSIDE the chroot, do something like:"
 echo "  ./image_to_usb.sh --from=${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."
 
 trap - EXIT