Support an option to infer --disk {disk} based on an efi system mount point

[colemickens]

I just wound up on a system where our grub-install was working fine, but efibootmgr was failing unless the --disk /dev/nvme0n1 was specified.

It seems that grub-install takes an --efi-directory that I suspect it uses to resolve to the boot drive, to then appropriately call efibootmgr.

But why? Why make every caller do that? It seems like there ought to be a way to say sudo efibootmgr --create --efi-dir /boot or something whereby efibootmgr does the disk resolution. Maybe there's an easy way to do the reverse boot resolution, but my first approach is a bunch of string hacks and again, I know this functionality already exists in disparate places.

[colemickens]

Right now I have to do something like this:

part=''$(mount | grep "${efiMount}" | cut -d ' ' -f 1)
part=''${part#/dev/}
disk=''$(readlink /sys/class/block/$part)
disk=''${disk%/*}
disk=/dev/''${disk##*/}

shim_loader_name="nixos-grub-shim-''${part}";

sudo efibootmgr --create --label "$shim_loader_name" --loader "${shim_path}" --disk "$disk"

[frozencemetery]

As in the other issue, I'm not sure what your question is here.

If it helps, on Fedora-likes we don't run grub-install at all for UEFI. Package installation dumps files in /boot/efi/EFI directly.

[colemickens]

Making the user manually resolve the ESP mount point to determine the disk to pass to efibootmgr seems, at the least, inconvenient. And it does seem lots of folks don't use grub-install, which has its own consequences I've been noticing, I think we are unfortunately in the same boat. But in fact that exacerbates my point, I'd bet code similar to what I shared exists in Fedora... and many others.

It seems like a reasonable thing to ask efibootmgr to know how to resolve the ESP mount point to determine the --disk parameter.

[frozencemetery]

It seems like a reasonable thing to ask efibootmgr to know how to resolve the ESP mount point to determine the --disk parameter.

Sure, I'd be willing to review patches for that.

[colemickens]

Ack. I can't really claim to be able to get to this anytime soon, but this is what I'm doing now, maybe it can be helpful or a starting place to someone else. I also wrote this a while ago and haven't re-reviewed it, so please don't trust it blindly:

part="$(mount | grep "${efiMount}" | cut -d ' ' -f 1)"
partdev="${part#/dev/}"

disk="/dev/$(echo $partdev | cut -d 'p' -f1)"
partno="$(cat /sys/class/block/$partdev/partition)"

# later
efibootmgr ... --disk "$disk" --part "$partno"