[PATCH v2 1/1] efi_loader: expose the device-tree file name

[Simon Glass]

Hi Heinrich,

On Tue, 17 Oct 2023 at 07:50, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
> Forward and backward compatibility of Linux kernel device-trees is
> sometimes missing. One solution approach is to load a kernel specific
> device-tree. This can either be done via a U-Boot scripts (like the one
> generated by Debian package flash-kernel or by a boot loader like GRUB.
> The boot loader approach currently requires to know the device-tree name
> before first boot which makes it unusable for generic images.
>
> Expose the device-tree file name as EFI variable FdtFile.
> This will allow bootloaders to load a kernel specific device-tree.
>
> The variable will not be exposed on ACPI based systems or if the
> environment variable fdtfile is not defined.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
> v2:
>         Use a unique GUID to enable future U-Boot independent
>         standardization.
>         Do not try to add the variable on ACPI based systems.
> ---
>  include/efi_loader.h       |  5 +++++
>  lib/efi_loader/efi_setup.c | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 35 insertions(+)

I was too slow to reply to v1.

Does grub load the DT? I was assuming that U-Boot would pass it on?
What is the interface between U-Boot and grub?

Regards,
Simon