efifs VS grub-btrfs

See also UEFI drivers that can read a bunch of other file systems (btrfs, ext2/3/4, HFS, ISO, NTFS, UFS/FFS, XFS, ZFS, etc):

* https://efi.akeo.ie

* https://github.com/pbatard/efifs

The UEFI spec specifies (§13.3) that firmware is only required to read FAT32/16/12, which is generally why your /boot/efi is VFAT/FAT32.

In theory you would still need a FAT32 efi 'stub' partition with the exFAT filesystem drivers which you have to load before loading the WinPE loader (bootmgfw.efi).

I am pretty sure that that I am doing something incorrectly with the configuration files for the rEFInd bootloader, but everything else should be correct. However, as I write this, I barely realized did I not use the following commands recommended from the "Usage" section from the aforementioned website where I downloaded the zfs_x64.efi driver file for rEFInd:

I found the drivers here https://efi.akeo.ie/ . Which means, that any EFI bootloader able to load them will be able to use them. They are not for bootloader, but it is the firmware which will use them. As i said, i am little bit afraid that it will not work on any board as some manufacturers have pretty buggy firmware when talking about infrequently used features. Also i am bit unsure they will work with secure boot as they are gpl3 thus will be never signed by Microsoft and i don't know what UEFI requirements for drivers are in this regard.

Even for those using systemd-boot with custom efi drivers to provide functionality, it's worth noting that those drivers are being developed downstream of GRUB.

I think you can also add btrfs filesystem support for sd-boot by including the EFI drivers for it on the EFI partition instead, from https://github.com/pbatard/efifs/releases I think. Haven't tried it myself though.

EFI doesn't actually mandate FAT for the system partition. The system partition can be any filesystem that the firmware supports.

Of course, pretty much all EFI implementations only support FAT, so it's a bit of a moot point; the only one I'm aware of that supports anything else is the one on Intel Macs, which also understands HFS+.

You can find a huge selection of EFI filesystem drivers at https://efi.akeo.ie/ but they're derived from GRUB and hence GPL, so don't expect the likes of American Megatrends to be bundling these any time soon.

Afaik the proper solution is to use https://github.com/Antynea/grub-btrfs/blob/master/initramfs/readme.md and/or rollback the root to a snapshot.

In fact I’m pretty knowledgeable around btrfs and snapshot-tools as well. :D I codevelop https://github.com/Antynea/grub-btrfs.

Something I noticed is that the instructions here before step 2 suggest that the files /etc/initcpio/install/grub-btrfs-overlayfs and /etc/initcpio/hooks/grub-btrfs-overlayfs might exist, and they don't for me. Worth noting that I installed through pacman, which may be a reason they don't exist if I'm reading those instructions correctly.

In Debian, I see that there is a custom installer "Spiral Linux" (https://spirallinux.github.io) with non-default settings that achieves the same kind of mechanism using "grub-btrfs" (https://github.com/Antynea/grub-btrfs) in combination with "snapper-rollback" (https://github.com/jrabinow/snapper-rollback) and a BTRFS subvolume layout suggested by the Arch wiki (https://wiki.archlinux.org/index.php/Snapper#Suggested_filesystem_layout).

grub-btrfs

When the issue first arrived (around 01/11/2023, IIRC), I did try posting an "Issue" on the GitHub page for grub-btrfs (located here), & more specifically on Issue #254, however, for whatever reason (at that time) I wasn't able to make a post on that Issue/forum.