[PATCH v1 0/2] 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 boot_loader_interface, 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-genereator [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/

Oliver Steffen (2):
  efi: add grub_variable_with_attributes
  Add a module for the Boot Loader Interface

 grub-core/Makefile.core.def                |   6 +
 grub-core/commands/boot_loader_interface.c | 217 +++++++++++++++++++++
 grub-core/kern/efi/efi.c                   |  19 +-
 include/grub/efi/efi.h                     |   6 +
 4 files changed, 242 insertions(+), 6 deletions(-)
 create mode 100644 grub-core/commands/boot_loader_interface.c

-- 
2.39.0