[PATCH v2 0/7] Add basic Boot Loader Interface support

[Oliver Steffen]

This is a step towards supporting unified kernel images (UKI) in Grub.

Add a new module named bli, which provides a command with the same name.
It implements a small but quite useful part of the Boot Loader Interface
[0].  This interface uses EFI variables for communication between the
boot loader and the operating system.

This module sets two EFI variables under the vendor GUID
4a67b082-0a4c-41cf-b6c7-440b29bb8c4f:

- LoaderInfo: contains GRUB + <version number>.
  This allows the running operating system to identify the boot loader
  used during boot.

- LoaderDevicePartUUID: contains the partition UUID of the
  EFI System Partition (ESP). This is used by
  systemd-gpt-auto-generator [1] to find the root partitions (and
  others too), via partition type IDs [2]. This is especially useful for
  UKIs, where the kernel command line is fixed and usually does not
  contain any information about the root partition.

This module is only available on EFI platforms.

[0] https://systemd.io/BOOT_LOADER_INTERFACE/
[1] 
https://www.freedesktop.org/software/systemd/man/systemd-gpt-auto-generator.html
[2] 
https://uapi-group.org/specifications/specs/discoverable_partitions_specification/

v2:
- Addressed comments from Daniel
- Added a print function for gpt guids
- Added integer overflow check in UTF16 conversion
- Added config drop-in file that loads the module on EFI

v1:
https://mail.gnu.org/archive/html/grub-devel/2023-01/msg00104.html

Oliver Steffen (7):
  efi: add grub_efi_set_variable_with_attributes
  efi: check for integer overflow in string conversion
  Add a module for the Boot Loader Interface
  util/grub.d: activate bli module on EFI
  partmap/gpt: add print function for guids
  commands/probe: use grub_gpt_part_guid_snprint
  commands/bli: use grub_gpt_part_guid_snprint

 grub-core/Makefile.core.def             |   6 +
 grub-core/commands/bli.c                | 209 ++++++++++++++++++++++++
 grub-core/commands/probe.c              |  11 +-
 grub-core/kern/efi/efi.c                |  25 ++-
 grub-core/partmap/gpt.c                 |  13 ++
 include/grub/efi/api.h                  |   5 +
 include/grub/efi/efi.h                  |   6 +
 include/grub/gpt_partition.h            |   6 +
 util/grub.d/25_boot_loader_interface.in |  34 ++++
 9 files changed, 300 insertions(+), 15 deletions(-)
 create mode 100644 grub-core/commands/bli.c
 create mode 100644 util/grub.d/25_boot_loader_interface.in

-- 
2.39.2