Re: [PATCH 6/6] gnu: Add grub-efi.

[Marius Bakke]

Ludovic Courtès <address@hidden> writes:

>> Relatedly, I think the way to build a 'multi-grub' is to have one
>> expression for each supported grub platform, and then consolidate
>> out/lib/grub from each.
>
> So in essence, GRUB itself supports only one platform at a time?

AFAICT yes. Gentoo works around this by running the build for each
user-specified platform and combining the outputs. Most other distros
just carry separate grub-pc and grub-efi packages.

>>> Now there are things I didn’t quite get.  Apparently you’re supposed to
>>> have a /boot/efi as a vfat partition, and ‘grub-install’ is supposed to
>>> detect it and install the EFI stuff, or so I thought (info "(grub)
>>> Installing GRUB using grub-install").
>>>
>>> However, ‘grub-install’ still seems to be installing for “i386-pc”
>>> instead of EFI.
>>>
>>> What am I missing?
>>
>> IIRC grub-install will detect and install for the running mode (pc, efi,
>> etc). So in a classic chicken-and-egg situation, you need to be booted
>> with UEFI mode for grub to select the correct installation platform!
>
> My understanding is that it would install for UEFI if it fines
> /boot/efi or if --efi-directory is passed.

I'm not so sure, but it's been a while since I played around with this.
At least building the 'gnu/system/install.scm' image works fine when
passing --efi-directory (see the bottom two patches from
https://lists.gnu.org/archive/html/guix-devel/2016-12/txtchTym4QVKr.txt ),
and I think it would choose i386-pc even if x86_64-efi was available
since the VM boots in BIOS mode.

Tangentially, I'm not aware of any way to build a "hybrid" ISO image
using only grub. I've started work on packaging syslinux/isolinux which
is what Debian uses for their hybrid UEFI/BIOS install image.

> BTW, as far as I’m concerned, most of the other patches are ready:
>
>   https://lists.gnu.org/archive/html/guix-devel/2016-11/msg00303.html
>   https://lists.gnu.org/archive/html/guix-devel/2016-11/msg00304.html
>
> Could you push them?

Done.

> The remaining issue is how to run fsck for vfat.
>
> Currently I still have a preference for something like what I suggested
> at:
>
>   https://lists.gnu.org/archive/html/guix-devel/2016-12/msg00095.html
>
> Thoughts?

This approach looks better than the one I started working on. It's not
clear to me how to pass the device to these procedures, or how
'check-file-system' will know which checker to use. We should try to
have this in place before 0.13 :-)

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