kernel build: use %U+1 for dm-verity booting

update_bootloaders.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 legacy/efi bootloader partitions.
 # It does not populate the templates, but can update a loop device.
 
 # --- BEGIN COMMON.SH BOILERPLATE ---
@@ skipping 59 matching lines @@
 FLAGS "$@" || exit 1
 eval set -- "${FLAGS_ARGV}"
 set -e
 
 # If not provided by chromeos-common.sh, this will update all of the
 # boot loader files (both A and B) with the data pulled
 # from the kernel_partition.  The default boot target should
 # be set when the rootfs is stuffed.
 if ! type -p update_x86_bootloaders; then
   update_x86_bootloaders() {
-    local old_root="$1"  # e.g., sd%D%P
+    local old_root="$1"  # e.g., /dev/sd%D%P or %U+1
     local kernel_cmdline="$2"
     local esp_fs_dir="$3"
     local template_dir="$4"
 
     # Pull out the dm="" values
     dm_table=
     if echo "$kernel_cmdline" | grep -q 'dm="'; then
       dm_table=$(echo "$kernel_cmdline" | sed -s 's/.*dm="\([^"]*\)".*/\1/')
     fi
 
     # Rewrite grub table
-    grub_dm_table_a=${dm_table//${old_root}/\$linuxpartA}
-    grub_dm_table_b=${dm_table//${old_root}/\$linuxpartB}
+    grub_dm_table_a=${dm_table//${old_root}/\/dev\/\$linuxpartA}
+    grub_dm_table_b=${dm_table//${old_root}/\/dev\/\$linuxpartB}
     sed -e "s|DMTABLEA|${grub_dm_table_a}|g" \
         -e "s|DMTABLEB|${grub_dm_table_b}|g" \
         "${template_dir}"/efi/boot/grub.cfg |
         sudo dd of="${esp_fs_dir}"/efi/boot/grub.cfg
 
     # Rewrite syslinux DM_TABLE
-    syslinux_dm_table_usb=${dm_table//\/dev\/${old_root}/${FLAGS_usb_disk}}
+    syslinux_dm_table_usb=${dm_table//${old_root}/${FLAGS_usb_disk}}
     sed -e "s|DMTABLEA|${syslinux_dm_table_usb}|g" \
         "${template_dir}"/syslinux/usb.A.cfg |
         sudo dd of="${esp_fs_dir}"/syslinux/usb.A.cfg
 
-    syslinux_dm_table_a=${dm_table//\/dev\/${old_root}/HDROOTA}
+    syslinux_dm_table_a=${dm_table//${old_root}/HDROOTA}
     sed -e "s|DMTABLEA|${syslinux_dm_table_a}|g" \
         "${template_dir}"/syslinux/root.A.cfg |
         sudo dd of="${esp_fs_dir}"/syslinux/root.A.cfg
 
-    syslinux_dm_table_b=${dm_table//\/dev\/${old_root}/HDROOTB}
+    syslinux_dm_table_b=${dm_table//${old_root}/HDROOTB}
     sed -e "s|DMTABLEB|${syslinux_dm_table_b}|g" \
         "${template_dir}"/syslinux/root.B.cfg |
         sudo dd of="${esp_fs_dir}"/syslinux/root.B.cfg
 
     # Copy the vmlinuz's into place for syslinux
     sudo cp -f "${template_dir}"/vmlinuz "${esp_fs_dir}"/syslinux/vmlinuz.A
     sudo cp -f "${template_dir}"/vmlinuz "${esp_fs_dir}"/syslinux/vmlinuz.B
 
     # The only work left for the installer is to pick the correct defaults
-    # and replace HDROOTA and HDROOTB with the correct /dev/sd%D%P.
+    # and replace HDROOTA and HDROOTB with the correct /dev/sd%D%P/%U+1
   }
 fi
 
 ESP_DEV=
 if [[ ! -e "${FLAGS_to}" ]]; then
   error "The ESP doesn't exist"
   # This shouldn't happen.
   info "Creating a new esp image at ${FLAGS_to}" anyway.
   # Create EFI System Partition to boot stock EFI BIOS (but not ChromeOS EFI
   # BIOS).  ARM uses this space to determine which partition is bootable.
@@ skipping 49 matching lines @@
   # after the rootfs work is done.
   sudo mkdir -p "${ESP_FS_DIR}"/syslinux
   sudo cp -r "${FLAGS_from}"/syslinux/. "${ESP_FS_DIR}"/syslinux
 
   # Stage both kernels with the only one we built.
   sudo cp -f "${FLAGS_vmlinuz}" "${ESP_FS_DIR}"/syslinux/vmlinuz.A
   sudo cp -f "${FLAGS_vmlinuz}" "${ESP_FS_DIR}"/syslinux/vmlinuz.B
 
   # Extract kernel flags
   kernel_cfg=
-  old_root="sd%D%P"
+  old_root="%U+1"
   if [[ -n "${FLAGS_kernel_cmdline}" ]]; then
     info "Using supplied kernel_cmdline to update templates."
     kernel_cfg="${FLAGS_kernel_cmdline}"
   elif [[ -n "${FLAGS_kernel_partition}" ]]; then
     info "Extracting the kernel command line from ${FLAGS_kernel_partition}"
     kernel_cfg=$(dump_kernel_config "${FLAGS_kernel_partition}")
   fi
   update_x86_bootloaders "${old_root}" \
                          "${kernel_cfg}" \
                          "${ESP_FS_DIR}" \
@@ skipping 10 matching lines @@
 elif [[ "${FLAGS_arch}" = "arm" ]]; then
   # Copy u-boot script to ESP partition
   if [ -r "${FLAGS_from}/boot-A.scr.uimg" ]; then
     sudo mkdir -p "${ESP_FS_DIR}/u-boot"
     sudo cp "${FLAGS_from}/boot-A.scr.uimg" \
       "${ESP_FS_DIR}/u-boot/boot.scr.uimg"
   fi
 fi
 
 set +e