Re: [gentoo-user] rescue cd for zfs 2.1 or thereabouts

[Neil Bothwick]

On Tue, 31 Aug 2021 20:44:50 +0100, Michael wrote:

> > systemd-boot and refind both support everything on EFI. I am pretty
> > sure GRUB does too, but I have no reason to use GRUB with EFI. My
> > setup on this box is /boot on FAT32 and / (and everything else) on
> > btrfs. I've also used the same setup with ZFS.
>
> Any boot option on a UEFI MoBo requires an 'EFI System Partition'
> (ESP), formatted as VFAT.  The UEFI firmware boot loader will
> list/load/run any *.efi software stored in the ESP compatible with the
> UEFI API, whether this is a boot loader, a kernel with an EFI stub, or
> some .efi diagnostic application.
>
> As long as your boot loader of choice, or kernel image and any initrd
> contains the requisite fs drivers, there will be no problem mounting
> and accessing whatever root fs needs to be accessed.
>
> GRUB contains a number of ZFS modules to do this job (zfscrypt.mod,
> zfsinfo.mod, zfs.mod) - not sure about the other boot managers.
>
> Typical GRUB installations have /boot/efi mounted on the ESP, with the
> grubx64.efi image on it, while the rest of the files, vmlinuz symlinks,
> etc. are on the root partition.
>
> Please beware, I have not used zfs to date, only btrfs, so the above
> merely reflects my understanding rather than in depth experience of the
> difficulty in managing such a setup.

I find it simpler to make /boot a FAT partition, then /boot/efi is the
ESP and all boot-related files are on the same filesystem. Like you, I
have only used this with btrfs (and ext4 on LVM). I do use ZFS but that
system is not EFI.


-- 
Neil Bothwick

Theory is when you know everything, but nothing works.
Reality is when everything works, but you don't know why.
However, usually theory and reality are mixed together :
Nothing works, and nobody knows why not.