Re: [PATCH 4/5] efi_loader: disk: Extend EFI_PARTITION_INFO_PROTOCOL to support MBR

[Javier Martinez Canillas <javierm@redhat.com>]

Jan Kiszka <jan.kiszka@siemens.com> writes:

Hello Jan,

> On 20.01.26 14:36, Javier Martinez Canillas wrote:
>> The EFI_PARTITION_INFO_PROTOCOL provides detailed information about
>> partitions. The UEFI specification mentions that both GPT and MBR
>> partition schemes are supported, but the U-Boot implementation only
>> supports the former.
>> 
>> This can cause compatibility issues for platforms whose boot ROM only
>> supports MBR. This change adds support for MBR partition tables to
>> the protocol, making U-Boot compatible with systems that require a
>> legacy MBR table.
>
> Normally, this is simple to address via hybrid partition tables. I've
> done that already for two different SoCs (TI AM62 and Altera Cyclone V),
> and this allows to use all the nifty features of the modern GPT without
> upsetting the ROM loaders. Do you have a SoC where this does not work?
>

Yes, I know that could be worked around by using hybrid partition tables
but IMO using that could be fragile.

> That said, adding this feature may still be valuable.
>

Indeed and as mentioned in the commit message it is something supported by
the EFI partition info protocol according to the spec, so it makes sense
for U-boot to also implement support for MBR.

> Jan
>
> -- 
> Siemens AG, Foundational Technologies
> Linux Expert Center
>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat