CloverBootloader VS efifs

Definitely look into clover

You need to try and learn it ....clover is a bit eazy then OC https://github.com/CloverHackyColor/CloverBootloader/wiki/Configuration

I did manage to get Clover to boot, turns out it was a graphics card issue (Clover does not boot on ProLiant DL 560 Gen 8) so I threw an old HD 3470 I had laying around in it and I can now access Clover. I gonna play with Clover a little and see if I can get it to do what I want and if not, I grab the Slim ODD to SATA adapter you mentioned. Just need to find the cables to connect it.

In your case you may wish to research using a tool such as Clover Bootloader, which would allow you to install Proxmox to NVMe drives and then put Clover on an internal or external USB thumb drive. The boot process would start from Clover on USB before linking your NVMe installation and continuing from there.

Clover bootloader https://github.com/CloverHackyColor/CloverBootloader

You can use Clover to emulate UEFI on legacy BIOS computers.

Are there any other bootloaders I should be considering? My understanding was that LILO and BURG have essentially been abandoned so even if I were willing to rely on an abandoned project for something as important as the bootloader (I'm not btw) then it probably would not work with LUKS/Btrfs. While doing my initial research, I did come across Clover but I know even less about that than I do about Systemdboot and Refined. My initial impressions is that it seems very customizable theming-wise but it feels like maybe not too many people use it / I'd have a hard time finding help and that's IF it even supports LUKS/Btrfs.

You Clover outdated af (2017). Update to 5123.1, which is the last one with the old memory fixes: https://github.com/CloverHackyColor/CloverBootloader/releases/tag/5123.1

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.