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

[Marius Bakke <mbakke@fastmail.com>]

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Ludovic Courtès <ludo@gnu.org> writes:

> 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)?

The problem is missing UEFI firmware for the qemu calls. But we indeed
no longer need qemu@1.3.1 for the tests, at least on x86_64. I replaced
it with 'qemu-minimal'. Pushed!

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