Re: [OE-core] [PATCH v3 01/11] systemd: enable efi support by default

Ilias Apalodimas
2025-04-10T16:51:24Z

Hi Alexander

On Thu, 10 Apr 2025 at 15:13, Alexander Kanavin <alex.kanavin@gmail.com> wrote:
>
> On Thu, 10 Apr 2025 at 13:50, Ilias Apalodimas via
> lists.openembedded.org
> <ilias.apalodimas=linaro.org@lists.openembedded.org> wrote:
> > > I would therefore like to see the EFI implementation remain
> > > opt-in until it covers at least the most important use cases for robust
> > > embedded systems. What I primarily miss with EFI is a reference
> > > implementation for an A/B update system without having to rely on a FAT
> > > partition without journaling. Please correct me if I'm missing
> > > something!
> >
> > Where does the FAT partition requirement come from?
>
> https://uefi.org/sites/default/files/resources/UEFI%202_5.pdf#page=585
>
> This is what one has to use to store that critical bit of info ('A' or
> 'B'?) and the bootloader code that picks one or the other, reads the
> kernel from it, and hands over the boot process. I'd say these are
> extremely critical things, and yet FAT design as hopefully everyone's
> aware is a 1980s MS DOS relic that is notorious for lack of metadata
> robustness and its frequent corruption.

I think you are misinterpreting that. That paragraph says "The file
system supported by the Extensible Firmware Interface is based on FAT"
-- IOW your *firmware* must support FAT.
It never dictates that the ESP has to be FAT as well. You are free to
format your ESP to whatever FS your board supports. For example, x86
macs use HFS IIRC.

Thanks
/Ilias
>
> Alex