Hi Ludwig, On Mon, 24 Nov 2025 at 02:21, Nussel, Ludwig <ludwig.nussel@siemens.com> wrote:
On Tue, 2025-11-18 at 11:55 -0700, Simon Glass wrote:
[...] Yes and I'm not too keen on that approach: - we cannot have a system relying on FAT since it can become corrupted if the media is yanked out (power failure, etc.)
Certainly (V)FAT isn't the most beautiful nor most simple FS for the purpose. But then which one would you choose?
ext4 as it can survive power failure and is relatively simple (compared to some).
Hmm, that means the bootloader has to deal with the complexity of also handling the journal though.
Yes, that's right. We discussed this a bit in the U-Boot call today. Tom suggested pulling in ext4 from Linux somehow.
- Type 1 is actually based on extlinux and has some benefits, but we cannot use that spec unless it supports FIT - Type 2 requires EFI so is a non-starter for systems that want to boot without it
I had a brief chat with Luca on all-systems-go, his concern with adding FIT to the official document was mostly that no other bootloader supports FIT. I found that at least barebox also supports it. So probably just a matter of coordination for broader support. Anyway U- Boot could just support FIT as extension from the standard while still following the general architecture and naming scheme.
Well, also Tianocore[1] and coreboot (for many years) at least. What other bootloaders are there, actually?
Ok, cool. I didn't know that.
Universal Payload Specification uses FIT as the file format and device tree (with some schema additions) as the handoff format.
The response I received on FIT was unfortunate, to say the least. To me it actually came across more as ignorance than anything else. I would love to see that issue reopened for some discussion. Please see if Luca might be open to that.
I do have the impression that the embedded, potentially non-EFI use case is a separate world that is not really that visible on the radar on systemd side indeed. The next chance to meet the group in person might be at FOSDEM. Unfortunately no dedicated devroom this year. Are you going there?
We definitely have two separate worlds, but I would like to bring them together. At present I'm in NZ at the end of January, so FOSDEM is unlikely. What else is on the calendar next year?
Another idea outlined in a talk about MBR booting at all-systems-go was to just treat the PE files as archive format. Ie don't execute a UKI but rather load it's kernel and initrd, then boot that without EFI.
Sure, but why? Using an EFI executable file as a container format is just not a good idea. FIT has a proper schema and is much more extensible.
I too find this abuse of PE stuff disturbing :-) It's just taking ties to EFI a bit too far IMO. Nevertheless the ability to read those files is a way to deal with the currently used formats.
Yes, it is a pragmatic solution within the limitations of EFI (FAT, EFI apps). But we should not build the world on it. Regards, Simon