flatcar-postinst: Remove old kernel copying and bootloader handling

Flatcar doesn't ship the kernel image on /usr since 2021 and this anyway
didn't support dm-verity setups. The old bootloader handling is anyway
not needed for a long time now and also doesn't work without the kernel.
Remove the broken kernel and bootloader handling.

Author: pothos

flatcar-postinst

@@ -10,13 +10,6 @@ OEM_MNT="/usr/share/oem"
 
 INSTALL_MNT=$(dirname "$0")
 INSTALL_DEV="$1"
-INSTALL_KERNEL=""
-
-for arg in "$@"; do
-    case "${arg}" in
-        KERNEL=*) INSTALL_KERNEL="${arg#KERNEL=}" ;;
-    esac
-done
 
 # Figure out if the slot id is A or B
 INSTALL_LABEL=$(blkid -o value -s PARTLABEL "${INSTALL_DEV}")
@@ -30,71 +23,6 @@ case "${INSTALL_LABEL}" in
         exit 1
 esac
 
-# Find the ESP partition and mount it if needed
-ESP_PARTTYPE="c12a7328-f81f-11d2-ba4b-00a0c93ec93b"
-ESP_MNT=
-
-declare -a DEV_LIST
-mapfile DEV_LIST < <(lsblk -P -o NAME,PARTTYPE,MOUNTPOINT)
-
-for dev_info in "${DEV_LIST[@]}"; do
-    eval "$dev_info"
-
-    if [[ "${PARTTYPE}" != "${ESP_PARTTYPE}" ]]; then
-        continue
-    fi
-
-    if [[ -n "${MOUNTPOINT}" ]]; then
-        ESP_MNT="${MOUNTPOINT}"
-    else
-        ESP_MNT="$(mktemp -d /tmp/postinst_esp.XXXXXXXXXX)"
-        mount "/dev/${NAME}" "${ESP_MNT}"
-        trap "umount '${ESP_MNT}' && rmdir '${ESP_MNT}'" EXIT
-    fi
-
-    break
-done
-
-if [[ -z "${ESP_MNT}" ]]; then
-    echo "Failed to find ESP partition!" >&2
-    exit 1
-fi
-
-if [[ ! -d "${ESP_MNT}" ]]; then
-    echo "ESP partition mount point (${ESP_MNT}) is not a directory!" >&2
-    exit 1
-fi
-
-# Update bootloaders from CoreOS <= 522.x.x
-if grep -q cros_legacy /proc/cmdline; then
-    # Update kernel and bootloader configs
-    mkdir -p "${ESP_MNT}"{/syslinux,/boot/grub}
-    cp -v "${INSTALL_MNT}/boot/vmlinuz" \
-        "${ESP_MNT}/syslinux/vmlinuz.${SLOT}"
-    cp -v "${INSTALL_MNT}/boot/syslinux/root.${SLOT}.cfg" \
-        "${ESP_MNT}/syslinux/root.${SLOT}.cfg"
-
-    # For Xen's pvgrub
-    cp -v "${INSTALL_MNT}/boot/grub/menu.lst.${SLOT}" \
-        "${ESP_MNT}/boot/grub/menu.lst"
-
-    # For systems that have disabled boot_kernel and kexec
-    if ! grep -q boot_kernel "${ESP_MNT}/syslinux/default.cfg"; then
-        cp -v "${INSTALL_MNT}/boot/syslinux/default.cfg.${SLOT}" \
-            "${ESP_MNT}/syslinux/default.cfg"
-    fi
-elif [[ -z "${INSTALL_KERNEL}" ]]; then
-    # not a legacy system but update_engine didn't handle the kernel.
-    # kernel names are in lower case, ${SLOT,,} converts the slot name
-    if [ -e "${ESP_MNT}/coreos/vmlinuz-a" ] || [ -e "${ESP_MNT}/coreos/vmlinuz-b" ]; then
-        cp -v "${INSTALL_MNT}/boot/vmlinuz" \
-           "${ESP_MNT}/coreos/vmlinuz-${SLOT,,}"
-    else
-        cp -v "${INSTALL_MNT}/boot/vmlinuz" \
-           "${ESP_MNT}/flatcar/vmlinuz-${SLOT,,}"
-    fi
-fi
-
 # If the OEM provides a hook, call it
 if [[ -x "${OEM_MNT}/bin/oem-postinst" ]]; then
     "${OEM_MNT}/bin/oem-postinst" "${SLOT}" "${INSTALL_MNT}"

src/update_engine/omaha_response_handler_action.cc

@@ -112,25 +112,8 @@ bool OmahaResponseHandlerAction::GetInstallDev(const std::string& boot_dev,
   return true;
 }
 
-namespace {
-bool IsCrosLegacySystem() {
-  string cmdline;
-  TEST_AND_RETURN_FALSE(
-      files::ReadFileToString(files::FilePath("/proc/cmdline"), &cmdline));
-  return cmdline.find("cros_legacy") != string::npos;
-}
-}  // namespace
-
 bool OmahaResponseHandlerAction::GetKernelPath(const std::string& part_path,
                                                std::string* kernel_path) {
-  // If 'cros_legacy' is in the kernel args we are on an old system
-  // using SYSLINUX style bootloader configuration. Leave the kernel to
-  // the post install script on such systems.
-  if (IsCrosLegacySystem()) {
-    *kernel_path = "";
-    return true;
-  }
-
   files::FilePath coreos_kernel_a = files::FilePath("/boot/coreos/vmlinuz-a");
   files::FilePath coreos_kernel_b = files::FilePath("/boot/coreos/vmlinuz-b");