Re: Unexpected prefix value

[Andrei Borzenkov]

On 27.11.2023 23:06, Pascal Hambourg wrote:
> Hello,
>
> Distribution: Debian 12 (bookworm)
> GRUB version: 2.06
>
> If I build an EFI GRUB core image with
>
>    grub-mkimage --prefix='(hd0,gpt4)/' --format=x86_64-efi \
>     --output=/boot/efi/EFI/azerty/core.efi part_gpt ext2
>
> when booting it, $prefix has the expected value:
>
>    cmdpath=(hd0,gpt1)/EFI/azerty
>    prefix=(hd0,gpt4)/
>
> But if I build an EFI GRUB core image with
>
>    grub-mkimage --prefix='(hd0,gpt4)' --format=x86_64-efi \
>     --output=/boot/efi/EFI/azerty/core.efi part_gpt ext2
>
> (no / at the end of prefix), then when booting it, the $prefix value
> seems to be the combination of the --prefix device and the $cmdpath path:
>
>    cmdpath=(hd0,gpt1)/EFI/azerty
>    prefix=(hd0,gpt4)/EFI/azerty
>
> Is this expected behaviour ?

Yes. $prefix consists of two parts - device and the directory path. If 
one of them is missing during initialization, grub attempts to guess and 
fill it in.