Porting U-Boot's UEFI Payload to coreboot

[Heinrich Schuchardt]

On 3/8/22 13:59, Ahamed Husni wrote:
> Hi everyone,
>
> I am trying to work on a project to port the U-Boot UEFI code to coreboot
> as a payload.
> I haven't worked with UEFI before except running a basic EFI payload in a
> coreboot/u-boot environment. (Serial output:
> https://gist.github.com/drac98/6166d29f6c3a2baf2f4e791925ea98d3)
>
> I would like to know how UEFI is implemented in U-Boot. Is UEFI integrated
> into u-boot or is it implemented like a payload?

Hello Ahamed,

the UEFI API implementation is an integral part of U-Boot.

>
> Where is the UEFI source code? Is it the following files in the tree
> https://source.denx.de/u-boot/custodians/u-boot-efi
> lib/
> |__ efi/
> |__ efi_driver/
> |__ efi_loader/

U-Boot can both be run on top of UEFI. This is the code you find in
/lib/efi/. Furthermore UEFI can run as a firmware providing the UEFI
API. This is what you find in /lib/efi_loader/ and /lib/efi_driver/.

You can build U-Boot as payload for coreboot which offers the UEFI API
implementation. See configs/coreboot64_defconfig.

U-Boot runs ARM and RISC-V Linux successfully via UEFI.

What architecture are you looking at?

Simon (on CC) has been working on U-Boot on UEFI and Coreboot while I
have concentrated on the UEFI API implementation in U-Boot.

Best regards

Heinrich

>
>
> Please help me understand the structure.
>
> Best regards,
> Husni.
>