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

[ludo@gnu.org (Ludovic Courtès)]

Marius Bakke <mbakke@fastmail.com> skribis:

> Ludovic Courtès <ludo@gnu.org> writes:
>
>> Hi Marius,
>>
>> Marius Bakke <mbakke@fastmail.com> skribis:
>>
>>> Ludovic Courtès <ludo@gnu.org> 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.
>>
>> OK.
>>
>> Having checked GRUB’s configure.ac etc., I realize that my suggestion of
>> having one ‘grub’ package doing both EFI and “PC” cannot work.  What you
>> suggested initially (a separate ‘grub-efi’ package) is the only thing we
>> can do (we could perhaps merge the lib/grub directories as you
>> suggested, but it’s not even clear that this would work.)
>>
>> Thus, I think we need to revert 3eee16130d858ae96510ec1c7d38d31290de2699
>> and install your initial ‘grub-efi’ patch.  How does that sound?
>
> OK. I'll try to find out why tests don't work with the UEFI variant
> first in order to at least write a meaningful comment. Maybe qemu needs
> UEFI support or something like that.

It might be that we no longer need QEMU 1.3.1 to run the tests (see the
top of gnu/packages/grub.scm)?

Ludo’.