[PATCH] efi_loader: improve detection of ESP for storing UEFI variables

[Heinrich Schuchardt]

On 09.11.20 14:24, Paulo Alcantara wrote:
> Heinrich Schuchardt <xypron.glpk at gmx.de> writes:
>
>> On 09.11.20 00:58, Paulo Alcantara wrote:
>>> The UEFI specification does not restrict on the number and location of
>>> ESPs in a system.  They are discovered as required by looking at the
>>> partition type, but firmware implementations are allowed to support
>>> ESPs which do not contain a valid partition type.
>>
>> I guess you refer to chapter "13.3.3 Number and Location of System
>> Partitions" of the UEFI spec saying: "Further, UEFI implementations
>> may allow the use of conforming FAT partitions which do not use the
>> ESP GUID."
>
> Yep, sorry.  Thanks for pointing it out!
>
>> Why should U-Boot support FAT partitions that are not of type FAT 0xef
>> and GPT partition that do not use the ESP GUID?
>
> In most UEFI (EDK2-based) systems I used, I could boot my OSes and
> diagnostic tools by simply having a supported filesystem (FAT12/16/32)
> and /EFI/BOOT/BOOT{ARCH}.EFI file and never cared about setting the
> partition type at all.  It took me a while for figuring out why I
> couldn't get my UEFI variables loaded from my FAT partition that
> contained /ubootefi.var and /EFI/BOOT/BOOTAA64.efi files.
>
> I am not trying to support ESPs that lack the appropriate partition type
> everywhere in U-Boot, but at least for the UEFI variables (ubootefi.var)
> feature seemed a nice thing to have.
>
> Perhaps we could make it a separate config option like "Allow searching
> for ESPs without partition type" and default it to N, don't know...
>

In your last mail you wrote you are working for SUSE. Is there a bug in
the SUSE installer that makes it create the wrong partition type?

Best regards

Heinrich