installer/chromeos-install-kernel

#!/bin/sh
#
# Copyright 2022 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
# Install kernel and kernel modules from USB.  This script is used by ChromeOS
# kernel developers to recover from bad kernel updates.

# If we're not running as root, restart as root.
if [ "${UID:-$(id -u)}" -ne 0 ]; then
  exec sudo "$0" "$@"
fi

# Load functions and constants.
. /usr/share/misc/shflags || exit 1
. /usr/share/misc/chromeos-common.sh || exit 1
. /usr/sbin/write_gpt.sh || exit 1
load_base_vars

DEFINE_boolean clean "${FLAGS_TRUE}"  "Remove modules for old kernels"
DEFINE_boolean debug "${FLAGS_FALSE}" "Show debug output"

TMPMNT="$(mktemp -d)"

# Parse the command line.
FLAGS "$@" || exit 1
eval set -- "${FLAGS_ARGV}"

# Be aggressive in our error checking.  shflags functions leak non-zero error
# codes, so this has to be set after we're done parsing flags.
set -eu

remove_rootfs_verification() {
  local rootdev="$1"
  local partition="$2"
  local device

  device="$(make_partition_dev "${rootdev}" "${partition}")"

  # See remove_rootfs_verification() in make_dev_ssd.sh for how the kernel
  # config is modified when rootfs verification is off.
  if dump_kernel_config "${device}" | grep -q "root=/dev/dm"; then
    /usr/share/vboot/bin/make_dev_ssd.sh --remove_rootfs_verification -i \
      "${rootdev}" --partitions "${partition}"
  fi
}

cleanup() {
  set +eu
  if mount | grep -q "${TMPMNT}"; then
    umount "${TMPMNT}"
  fi
  rmdir "${TMPMNT}"
}

main() {
  local device
  local partition
  local rootdev
  local usbdev
  local version

  trap cleanup EXIT

  rootdev="$(get_fixed_dst_drive)"
  usbdev="$(rootdev -s -d)"
  version="$(uname -r)"

  if [ "${FLAGS_debug}" = "${FLAGS_TRUE}" ]; then
    set -x
  fi

  if [ "${rootdev}" = "${usbdev}" ]; then
    echo "Error: target and destination are the same: ${rootdev}"
    exit 1
  fi

  # Rootfs verification needs to be removed from the rootdev partitions so that
  # we can mount them and push new modules.  We remove it from the usbdev so
  # when we copy that kernel to rootdev it will boot successfully.
  remove_rootfs_verification "${rootdev}" "${PARTITION_NUM_KERN_A}"
  remove_rootfs_verification "${rootdev}" "${PARTITION_NUM_KERN_B}"
  remove_rootfs_verification "${usbdev}"  "${PARTITION_NUM_KERN_A}"

  for partition in "${PARTITION_NUM_ROOT_A}" "${PARTITION_NUM_ROOT_B}"; do
    device="$(make_partition_dev "${rootdev}" "${partition}")"

    mount "${device}" "${TMPMNT}"
    if [ "${FLAGS_clean}" = "${FLAGS_TRUE}" ]; then
      rm -rf "${TMPMNT}"/lib/modules/*
    else
      rm -rf "${TMPMNT}"/lib/modules/"${version}"
    fi

    cp -a /lib/modules/"${version}" "${TMPMNT}"/lib/modules/
    umount "${TMPMNT}"
  done

  device="$(make_partition_dev "${usbdev}" "${PARTITION_NUM_KERN_A}")"
  for partition in "${PARTITION_NUM_KERN_A}" "${PARTITION_NUM_KERN_B}"; do
    local target_device
    target_device="$(make_partition_dev "${rootdev}" "${partition}")"
    dd if="${device}" of="${target_device}" bs=4M
  done

  sync
  cleanup
  trap - EXIT

  echo "------------------------------------------------------------"
  echo "Installation to '${rootdev}' complete."
}

main "$@"