Re: GRUB search doesn't set btrfs subvolume

[Lyubomir Parvanov]

On Sun, 12 Mar 2023 at 08:21, Andrei Borzenkov <arvidjaar@gmail.com> wrote:

> On 11.03.2023 22:46, Lyubomir Parvanov wrote:
> >>
> >> And what is this search command?
> >>
> > https://www.gnu.org/software/grub/manual/grub/html_node/search.html
> >
>
> I know what grub search command is. You said "call to the search command
> in order to set the prefix environment variable. But as far as I
> understand it doesn't take into account the btrfs subvolumes" and I
> asked you to show this search command invocation.
>
There's the menuentry named "Ubuntu" (the one that is booted) with the
following call on line 181 of the grub.cfg file that i attached:
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2
--hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2
 5f772e81-6e8f-4194-b9b7-5de280170447

I just got up this morning and had an eureka moment now:
1. I remembered that more than a week ago i actually moved grub from the
root btrfs volume to a subvolume.
2. I wondered if it's not searching for something built into its executable
3. i found out the initial grub config at
/boot/efi/EFI/ubuntu/grub.cfg with the
following content:
search.fs_uuid 5f772e81-6e8f-4194-b9b7-5de280170447 root hd0,gpt2
set prefix=($root)'/grub'
configfile $prefix/grub.cfg

So i think i understand what's happening here. GRUB can't find it's main
config because the bootstrap config in the boot/efi tells it/still thinks
it's located on the root btrfs instead of on a subvolume.
I just didn't think of this back at the moment cause after all it stays the
same /boot/efi path. But i totally didn't realize that this is itself
relative to the root/prefix.
I think i gotta reinstall grub and see if that'll fix things.