Re: [PATCH 3/3] efi_loader: disk: add EFI_PARTITION_INFO_PROTOCOL support

[Heinrich Schuchardt]

Am 13. Juni 2025 16:54:48 MESZ schrieb Javier Martinez Canillas <javierm at redhat.com>:
>Heinrich Schuchardt <xypron.glpk at gmx.de> writes:
>
>Hello Heinrich,
>
>Thanks for your feedback.
>
>> Am 13. Juni 2025 10:57:38 MESZ schrieb Javier Martinez Canillas <javierm at redhat.com>:
>>>The UEFI 2.10 specification mentions that this protocol shall be installed
>>>along with EFI_BLOCK_IO_PROTOCOL. It provides cached partition information
>>>for MBR and GPT partition types.
>>
>> U-Boot is targeting the EBBR specifcation which defines a subset of UEFI.
>>
>
>Interesting. I knew that the u-boot EFI implementation was to support
>SystemReady IR (what is now called SystemReady DeviceTree) and EBBR,
>but I didn't know that meant to only implement what's required by EBBR.
>
>I noticed that EFI_PARTITION_INFO_PROTOCOL is not even required by SBBR
>and only EFI_BLOCK_IO_PROTOCOL is required there just like for EBBR.
>
>> Which application needs this protocol?
>
>We are experimenting with a new A/B boot protocol and an EFI binary that
>implements it. It's inspired on what the Android Boot Loader does for its
>A/B booting too.
>
>The project is https://gitlab.com/CentOS/automotive/src/ukiboot and reads
>UKI (https://uapi-group.org/specifications/specs/unified_kernel_image)
>images from raw data partitions. Just like ABL reads Android Boot images.

Linaro already implemented A/B EFI Boot in U-Boot. (https://docs.u-boot.org/en/latest/develop/uefi/fwu_updates.html). What are you missing in the existing solution?

Best regards 

Heinrich

>
>> Are you planning to add it to the EBBR specification?
>>
>
>I haven't thought about it before but I also didn't know that u-boot had
>this requirement. Probably it should be documented somewhere to make it
>more clear? Maybe I didn't look enough but didn't find a doc in the repo.
>
>> Best regards 
>>
>> Heinrich 
>>
>