Re: RFC: A partition for grubenv, etc.

[Chris Murphy]

On Wed, May 26, 2021 at 2:08 AM Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
>
> On Tue, May 25, 2021 at 04:58:23PM -0600, Chris Murphy wrote:
> > Hi,
> >
> > It's not possible for GRUB pre-boot environment to write to grubenv
> > when it's on Btrfs, ZFS, LVM, mdadm raid, or LUKS. Also, at least XFS
> > upstream is super skeptical of anything except kernel code making any
> > kind of modification inside the file system region, and I suspect it's
> > the same concern with ext4 developers too. While there are file system
> > specific locations for bootloader usage, they're all different and
> > quite small. XFS has none. ext4 has 512 bytes. Btrfs has maybe 1 or 2
> > MiB, ZFS (?), mdadm (?) and LVM (?).
>
> Aren't most distro setups using EFI which in effect means GRUB has to
> deal most of the time with FAT32 file system? Does that work?

I'm not sure what most distros do, but grub-install creates a
grubx64.efi that expects to find /boot/grub/grubenv and
/boot/grub/grub.cfg and at least on Fedora we've unified UEFI and BIOS
GRUBs so that they use /boot/grub2/ for configuration files, not least
of which is for user sanity, but for future cloud images that are dual
bootloader thus a single image can boot UEFI or BIOS VMs, with a
single consistent configuration location.


-- 
Chris Murphy