scripts/archlinux/create-efi-kernel.sh

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#!/bin/sh
#
# Purpose {{{
# This script will create an Unified Kernel + UEFI entry for ArchLinux
# 1. Verify dependancies (efibootmgr, objcopy…).
# 2. Clean older unified kernels.
# 3. Backup last unified kernel.
# 4. Create a new unified kernel from vmlinuz, initramfs, UUID of root,…
# 5. Ensure an UEFI entry exists for this unified kernel.
#
# 2023-08-17
# }}}
# TODO {{{
# 1. Encrypted LVM is not yet supported. See crypt_part_uuid relative comments.
# }}}
# Flags {{{
## Exit on error {{{
set -o errexit
## }}}
## Exit on unset var {{{
### Use "${VARNAME-}" to test a var that may not have been set
set -o nounset
## }}}
## Pipeline command is treated as failed {{{
### Not available in POSIX sh https://github.com/koalaman/shellcheck/wiki/SC3040
#set -o pipefail
## }}}
## Help with debugging {{{
### Call the script by prefixing it with "TRACE=1 ./script.sh"
if [ "${TRACE-0}" -eq 1 ]; then set -o xtrace; fi
## }}}
# }}}
# Vars {{{
PROGNAME=$(basename "${0}"); readonly PROGNAME
PROGDIR=$(readlink --canonicalize-missing $(dirname "${0}")); readonly PROGDIR
ARGS="${*}"; readonly ARGS
readonly NBARGS="${#}"
[ -z "${DEBUG-}" ] && DEBUG=1
## Export DEBUG for sub-script
export DEBUG
## Default values for Unified kernel
readonly ROOT_UUID_DEFAULT=$(findmnt --kernel --noheadings --output UUID -- /)
readonly ROOT_FSTYPE_DEFAULT=$(findmnt --kernel --noheadings --output FSTYPE -- /)
readonly CRYPT_PART_UUID_DEFAULT=$(blkid | sed --silent 's;/dev/.*_crypt.*UUID="\(.*\)".*TYPE=.*;\1;p')
readonly UEFI_BOOT_STUB_FILE_DEFAULT="/usr/lib/systemd/boot/efi/linuxx64.efi.stub"
## Default values for UEFI entry
readonly EFI_BASE_LABEL_DEFAULT="Arch Linux unified"
readonly EFI_MOUNT_PATH_DEFAULT="/boot/efi"
## Temp files
readonly temp_kernel_command_file="/tmp/kernel.command.temp"
## Colors
readonly PURPLE='\033[1;35m'
readonly RED='\033[0;31m'
readonly RESET='\033[0m'
readonly COLOR_DEBUG="${PURPLE}"
# }}}
usage() { # {{{
cat <<- HELP
usage: $PROGNAME [-d|-h|-b|-f|-k|-u|-l|-m]
Script to build unified kernel for Arch Linux will all required informations
(vmlinuz, initramfs, UUID of root's partition,…) and create an UEFI entry.
EXAMPLES:
- Build unified kernel with default :
${PROGNAME}
- Build unified kernel with current command line :
${PROGNAME} --kernel "\$(< /proc/cmdline)"
OPTIONS:
-d,--debug
Enable debug messages.
-h,--help
Print this help message.
Unified kernel OPTIONS :
-b,--boot-stub,--uefi-boot
Define UEFI boot stub file to use.
(default: ${UEFI_BOOT_STUB_FILE_DEFAULT})
For more infos, see: https://man.archlinux.org/man/linuxx64.efi.stub.7.en
-f,--fs,--root-fs
Define a different root partition's filesystem.
(default: ${ROOT_FSTYPE_DEFAULT})
Thanks to command : findmnt --kernel --noheadings --output FSTYPE -- /
-u,--uuid,--root-uuid
Define a different root partition's UUID.
(default: ${ROOT_UUID_DEFAULT})
Thanks to command : findmnt --kernel --noheadings --output UUID -- /
-k,--kernel,--kernel-cmd
Define the kernel command line to use.
(default: build with root-fs|root-uuid and add_efi_memmap + ro options)
UEFI entry OPTIONS:
-l,--label
Set a new label for UEFI entry.
(default: ${EFI_BASE_LABEL_DEFAULT})
-m,--mount-path,--esp
Define a different mountpoint for the EFI partition.
(default: ${EFI_MOUNT_PATH_DEFAULT})
HELP
}
# }}}
debug_message() { # {{{
local_debug_message="${1}"
## Print message if DEBUG is enable (=0)
[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6b\e[m\n' "DEBUG ${PROGNAME}: ${local_debug_message}"
unset local_debug_message
return 0
}
# }}}
error_message() { # {{{
local_error_message="${1}"
local_error_code="${2}"
## Print message
printf '%b\n' "ERROR ${PROGNAME}: ${RED}${local_error_message}${RESET}" >&2
unset local_error_message
exit "${local_error_code:=66}"
}
# }}}
define_vars() { # {{{
# If root_uuid wasn't defined (argument) {{{
if [ -z "${root_uuid-}" ]; then
## Use default value
readonly root_uuid="${ROOT_UUID_DEFAULT}"
fi
# }}}
# If root_fstype wasn't defined (argument) {{{
if [ -z "${root_fstype-}" ]; then
## Use default value
readonly root_fstype="${ROOT_FSTYPE_DEFAULT}"
fi
# }}}
# If kernel_command_line wasn't defined (argument) {{{
if [ -z "${kernel_command_line-}" ]; then
## Use default value
readonly kernel_command_line="root=UUID=${root_uuid} rootfstype=${root_fstype} add_efi_memmap ro"
## For encrypted LVM
#readonly kernel_command_line="root=UUID=${root_uuid} rootfstype=${root_fstype} add_efi_memmap ro cryptdevice=UUID=${crypt_part_uuid}:lvm"
fi
# }}}
# If uefi_boot_stub_file wasn't defined (argument) {{{
if [ -z "${uefi_boot_stub_file-}" ]; then
## Use default value
readonly uefi_boot_stub_file="${UEFI_BOOT_STUB_FILE_DEFAULT}"
fi
# }}}
# If efi_base_label wasn't defined (argument) {{{
if [ -z "${efi_base_label-}" ]; then
## Use default value
readonly efi_base_label="${EFI_BASE_LABEL_DEFAULT}"
fi
# }}}
# If efi_mount_path wasn't defined (argument) {{{
if [ -z "${efi_mount_path-}" ]; then
## Use default value
readonly efi_mount_path="${EFI_MOUNT_PATH_DEFAULT}"
fi
# }}}
# If esp_device wasn't defined (argument) {{{
if [ -z "${esp_device-}" ]; then
## Use default value
readonly esp_device=$(findmnt -kno SOURCE "${efi_mount_path}" | grep --invert-match -- systemd | sed s-/dev/--)
fi
# }}}
# If esp_disk wasn't defined (argument) {{{
if [ -z "${esp_disk-}" ]; then
## Use default value
readonly esp_disk=$(lsblk /dev/"${esp_device}" -no pkname)
fi
# }}}
# If esp_part wasn't defined (argument) {{{
if [ -z "${esp_part-}" ]; then
## Use default value
readonly esp_part=$(cat /sys/class/block/"${esp_device}"/partition)
fi
# }}}
}
# }}}
is_command_available() { # {{{
local_command_available_cmd="${1}"
debug_prefix="${2:-}"
## Return False by default
return_command_available="1"
if [ "$(command -v ${local_command_available_cmd})" ]; then
debug_message "${debug_prefix}is_command_available \
${RED}${local_command_available_cmd}${COLOR_DEBUG} seems present on this host."
return_command_available="0"
else
debug_message "${debug_prefix}is_command_available \
${RED}${local_command_available_cmd}${COLOR_DEBUG} is not available on this host."
return_command_available="1"
fi
unset local_command_available_cmd
unset debug_prefix
return "${return_command_available}"
}
# }}}
main() { # {{{
debug_message "--- MAIN BEGIN"
## If a efibootmgr is missing {{{
### Exit with error message
is_command_available "efibootmgr" "| " \
|| error_message "No efibootmgr command available. Please install efibootmgr package with your package manager (pacman -S efibootmgr)." 01
## }}}
## If a objcopy is missing {{{
### Exit with error message
is_command_available "objcopy" "| " \
|| error_message "No objcopy command available. Please install binutils package with your package manager (pacman -S binutils)." 02
## }}}
## Define all vars
define_vars
debug_message "| Define vars"
## If UEFI boot stub is missing {{{
### Exit with error message
test -f "${uefi_boot_stub_file}" \
|| error_message "No UEFI boot stub file available (${uefi_boot_stub_file}). Please verify your systemd installation (systemd or systemd-boot-efi packages)." 03
## }}}
## Ensure EFI device is mounted {{{
if ! mountpoint --quiet "${efi_mount_path}"; then
mount "${efi_mount_path}" \
|| error_message "Can't mount EFI device" 04
fi
## }}}
## Put Kernel command line in temp file {{{
rm --force -- "${temp_kernel_command_file}" ; touch "${temp_kernel_command_file}"
printf "%s" "${kernel_command_line}" >> "${temp_kernel_command_file}"
## }}}
## Calculate address values to use for each section {{{
osrel_offs=$(objdump --section-headers -- "${uefi_boot_stub_file}" | awk 'NF==7 {size=strtonum("0x"$3); offset=strtonum("0x"$4)} END {print size + offset}')
cmdline_offs=$((osrel_offs + $(stat --dereference --format=%s -- "/usr/lib/os-release")))
linux_offs=$((cmdline_offs + $(stat --dereference --format=%s -- "${temp_kernel_command_file}")))
#linux_offs=$((cmdline_offs + $(stat --dereference --format=%s -- "/proc/cmdline")))
initrd_offs=$((linux_offs + $(stat --dereference --format=%s -- "/boot/vmlinuz-linux")))
## }}}
## Debug message {{{
debug_message "Try to build Unified kernel with from this informations :\r
* UEFI boot stub file: ${RED}${uefi_boot_stub_file}${COLOR_DEBUG}\r
* Root's UUID: ${RED}${root_uuid}${COLOR_DEBUG}\r
* Root's filesystem: ${RED}${root_fstype}${COLOR_DEBUG}\r
* Kernel command line: ${RED}${kernel_command_line}${COLOR_DEBUG}\r
* EFI device: ${RED}${esp_device}${COLOR_DEBUG}\r
* EFI disk: ${RED}${esp_disk}${COLOR_DEBUG}\r
* EFI partition number: ${RED}${esp_part}${COLOR_DEBUG}\r
Addresses values :\r
* osrel : ${RED}${osrel_offs}${COLOR_DEBUG}\r
* cmdline : ${RED}${cmdline_offs}${COLOR_DEBUG}\r
* linux : ${RED}${linux_offs}${COLOR_DEBUG}\r
* initrd : ${RED}${initrd_offs}${COLOR_DEBUG}\r
And generate UEFI entry :\r
* Label: ${RED}${efi_base_label}${COLOR_DEBUG}"
## }}}
## Ensure EFI mount path subdirectories exists
mkdir --parents -- "${efi_mount_path}/EFI/arch/"
## Create unified kernel blob {{{
objcopy \
--add-section .osrel="/usr/lib/os-release" --change-section-vma .osrel=$(printf 0x%x $osrel_offs) \
--add-section .cmdline="${temp_kernel_command_file}" --change-section-vma .cmdline=$(printf 0x%x $cmdline_offs) \
--add-section .linux="/boot/vmlinuz-linux" --change-section-vma .linux=$(printf 0x%x $linux_offs) \
--add-section .initrd="/boot/initramfs-linux.img" --change-section-vma .initrd=$(printf 0x%x $initrd_offs) \
"${uefi_boot_stub_file}" "${efi_mount_path}/EFI/arch/linux.arch.efi"
## }}}
## If no UEFI entry for this label + kernel {{{
## Create one
efibootmgr | grep --quiet -- "${efi_base_label}.*\\\EFI\\\arch\\\linux.arch.efi" \
|| efibootmgr --disk /dev/"${esp_disk}" --part "${esp_part}" --create --label "${efi_base_label}" --loader "\\EFI\\arch\\linux.arch.efi"
## }}}
## Remove temp files
rm --force -- "${temp_kernel_command_file}"
debug_message "--- MAIN END"
}
# }}}
# Manage arguments # {{{
# This code can't be in a function due to argument management
if [ ! "${NBARGS}" -eq "0" ]; then
manage_arg="0"
## If the first argument ask for help (h|help|-h|-help|-*h|-*help) {{{
if printf -- '%s' "${1-}" | grep --quiet --extended-regexp -- "^-*h(elp)?$"; then
usage
exit 0
fi
## }}}
## If the first argument is not an option
if ! printf -- '%s' "${1}" | grep --quiet --extended-regexp -- "^-+";
then
## Print help message and exit
printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
printf '%b\n' "---"
usage
exit 1
fi
# Parse all options (start with a "-") one by one
while printf -- '%s' "${1-}" | grep --quiet --extended-regexp -- "^-+"; do
case "${1}" in
## OPTIONS
-d|--debug ) ## debug
DEBUG=0
debug_message "--- Manage argument BEGIN"
;;
-h|--help ) ## display help message
usage
exit 0
;;
## Unified kernel OPTIONS
-u|--boot-stub|--uefi-boot ) ## Define uefi_boot_stub_file with given arg
## Move to the next argument
shift
## Define var
readonly uefi_boot_stub_file="${1}"
;;
-k|--kernel|--kernel-cmd ) ## Define kernel_command_line with given arg
## Move to the next argument
shift
## Define var
readonly kernel_command_line="${1}"
;;
-f|--fs|--root-fs ) ## Define root_fstype with given arg
## Move to the next argument
shift
## Define var
readonly root_fstype="${1}"
;;
-u|--uuid|--root-uuid ) ## Define root_uuid with given arg
## Move to the next argument
shift
## Define var
readonly root_uuid="${1}"
;;
## UEFI entry OPTIONS
-l|--label ) ## Define efi_base_label with given arg
## Move to the next argument
shift
## Define var
readonly efi_base_label="${1}"
;;
-m|--mount-path|--esp ) ## Define efi_mount_path with given arg
## Move to the next argument
shift
## Define var
readonly efi_mount_path="${1}"
;;
* ) ## unknow option
printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
printf '%b\n' "---"
usage
exit 1
;;
esac
debug_message "| ${RED}${1}${COLOR_DEBUG} option managed."
## Move to the next argument
shift
manage_arg=$((manage_arg+1))
done
debug_message "| ${RED}${manage_arg}${COLOR_DEBUG} argument(s) successfully managed."
else
debug_message "| No arguments/options to manage."
fi
debug_message "--- Manage argument END"
# }}}
main
exit 0