grub_install: use GRUB installed to the board root instead of SDK

Follow up to https://github.com/coreos/coreos-overlay/pull/1950

build_library/build_image_util.sh

@@ -379,10 +379,16 @@ finish_image() {
     for target in ${target_list}; do
       if [[ "${PROD_IMAGE}" -eq 1 && ${FLAGS_enable_verity} -eq ${FLAGS_TRUE} ]]; then
         ${BUILD_LIBRARY_DIR}/grub_install.sh \
-            --target="${target}" --disk_image="${disk_img}" --verity
+            --board="${BOARD}" \
+            --target="${target}" \
+            --disk_image="${disk_img}" \
+            --verity
       else
         ${BUILD_LIBRARY_DIR}/grub_install.sh \
-            --target="${target}" --disk_image="${disk_img}" --noverity
+            --board="${BOARD}" \
+            --target="${target}" \
+            --disk_image="${disk_img}" \
+            --noverity
       fi
     done
     ${BUILD_LIBRARY_DIR}/generate_grub_hashes.py ${disk_img} /usr/lib/grub/ ${pcr_dir} ${COREOS_VERSION}

build_library/grub_install.sh

@@ -14,6 +14,8 @@ SCRIPT_ROOT=$(readlink -f $(dirname "$0")/..)
 assert_inside_chroot
 
 # Flags.
+DEFINE_string board "${DEFAULT_BOARD}" \
+  "The name of the board"
 DEFINE_string target "" \
   "The GRUB target to install such as i386-pc or x86_64-efi"
 DEFINE_string disk_image "" \
@@ -26,15 +28,26 @@ FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 switch_to_strict_mode
 
+# must be sourced after flags are parsed.
+. "${BUILD_LIBRARY_DIR}/toolchain_util.sh" || exit 1
+. "${BUILD_LIBRARY_DIR}/board_options.sh" || exit 1
+
 # Our GRUB lives under coreos/grub so new pygrub versions cannot find grub.cfg
 GRUB_DIR="coreos/grub/${FLAGS_target}"
 
+# GRUB install location inside the SDK
+GRUB_SRC="/usr/lib/grub/${FLAGS_target}"
+
 # Modules required to boot a standard CoreOS configuration
 CORE_MODULES=( normal search test fat part_gpt search_fs_uuid gzio search_part_label terminal gptprio configfile memdisk tar echo )
 
 # Name of the core image, depends on target
 CORE_NAME=
 
+# Whether the SDK's grub or the board root's grub is used. Once amd64 is
+# fixed up the board root's grub will always be used.
+BOARD_GRUB=0
+
 case "${FLAGS_target}" in
     i386-pc)
         CORE_MODULES+=( biosdisk serial )
@@ -50,12 +63,20 @@ case "${FLAGS_target}" in
     arm64-efi)
         CORE_MODULES+=( serial efi_gop getenv smbios efinet verify http )
         CORE_NAME="core-arm64.efi"
+        BOARD_GRUB=1
         ;;
     *)
         die_notrace "Unknown GRUB target ${FLAGS_target}"
         ;;
 esac
 
+if [[ $BOARD_GRUB -eq 1 ]]; then
+    info "Updating GRUB in ${BOARD_ROOT}"
+    emerge-${BOARD} --nodeps --select -qugKN sys-boot/grub
+    GRUB_SRC="${BOARD_ROOT}/usr/lib/grub/${FLAGS_target}"
+fi
+[[ -d "${GRUB_SRC}" ]] || die "GRUB not installed at ${GRUB_SRC}"
+
 # In order for grub-setup-bios to properly detect the layout of the disk
 # image it expects a normal partitioned block device. For most of the build
 # disk_util maps individual loop devices to each partition in the image so
@@ -107,7 +128,7 @@ sudo mount -t vfat "${LOOP_DEV}p1" "${ESP_DIR}"
 sudo mkdir -p "${ESP_DIR}/${GRUB_DIR}"
 
 info "Compressing modules in ${GRUB_DIR}"
-for file in "/usr/lib/grub/${FLAGS_target}"/*{.lst,.mod}; do
+for file in "${GRUB_SRC}"/*{.lst,.mod}; do
     out="${ESP_DIR}/${GRUB_DIR}/${file##*/}"
     gzip --best --stdout "${file}" | sudo_clobber "${out}"
 done
@@ -149,7 +170,7 @@ info "Generating ${GRUB_DIR}/${CORE_NAME}"
 sudo grub-mkimage \
     --compression=auto \
     --format "${FLAGS_target}" \
-    --prefix "(,gpt1)/coreos/grub" \
+    --directory "${GRUB_SRC}" \
     --config "${ESP_DIR}/${GRUB_DIR}/load.cfg" \
     --memdisk "${ESP_DIR}/coreos/grub/grub.cfg.tar" \
     --output "${ESP_DIR}/${GRUB_DIR}/${CORE_NAME}" \
@@ -159,7 +180,7 @@ sudo grub-mkimage \
 case "${FLAGS_target}" in
     i386-pc)
         info "Installing MBR and the BIOS Boot partition."
-        sudo cp "/usr/lib/grub/i386-pc/boot.img" "${ESP_DIR}/${GRUB_DIR}"
+        sudo cp "${GRUB_SRC}/boot.img" "${ESP_DIR}/${GRUB_DIR}"
         sudo grub-bios-setup --device-map=/dev/null \
             --directory="${ESP_DIR}/${GRUB_DIR}" "${LOOP_DEV}"
         # boot.img gets manipulated by grub-bios-setup so it alone isn't