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

[Javier Martinez Canillas]

Heinrich Schuchardt <xypron.glpk at gmx.de> writes:

Hello Heinrich,

Thanks for your feedback.

> On 1/20/26 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.
>> 
>> To implement this, the existing part_get_info_extended() function,
>> which already traverses DOS partitions, is refactored to optionally
>> retrieve the raw MBR partition record. This provides the necessary
>> data for the EFI subsystem.
>> 
>> Signed-off-by: Javier Martinez Canillas <javierm at redhat.com>
>> ---
>> 
>>   disk/part_dos.c           | 63 ++++++++++++++++++++++++---------------
>>   include/part.h            | 14 +++++++++
>>   lib/efi_loader/efi_disk.c |  9 ++++--
>>   3 files changed, 59 insertions(+), 27 deletions(-)
>> 
>> diff --git a/disk/part_dos.c b/disk/part_dos.c
>> index 60c3d6773696..5b508483bae7 100644
>> --- a/disk/part_dos.c
>> +++ b/disk/part_dos.c
>> @@ -201,7 +201,9 @@ static void print_partition_extended(struct blk_desc *desc,
>
> Please add a Sphinx style function description describing the usage of 
> the parameters.
>

Sure, I didn't add for the new parameter since the function didn't have
a description, but I'll add a preparatory patch in v2 to add that.

[...]
   
>> +/**
>> + * part_get_mbr() - Get the MBR partition record of a partition
>> + *
>> + * This function reads the MBR partition record for a given block
>> + * device and partition number.
>> + *
>> + * @desc:	block device descriptor
>> + * @part:	partition number for which to return the partition record
>> + * @mbr:	MBR partition record
>> + *
>> + * Return:	0 on success, otherwise error
>> + */
>> +int part_get_mbr(struct blk_desc *desc, int part, dos_partition_t *mbr);
>> +
>>   #endif
>>   
>
> Please, put the partition library changes into one patch and the EFI 
> changes into another.
>

Ok, I'll split these in v2.

> Best regards
>
> Heinrich
>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat