uefi-elf-bootloader VS efifs

Thanks all for their answers! You helped alot! In the meanwhile I've found this example loader and kernel: https://github.com/ajxs/uefi-elf-bootloader In that project the dev has chosen to disable the watchdog timer and newer return from boot loader. This is the end of efi_main

Example code for loading an ELF kernel from UEFI: https://github.com/ajxs/uefi-elf-bootloader

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.