Requirements:
- you must have installed proxmox with root on zfs - aka when you installed proxmox you installed it on a zfs filesystem
mount /dev/nvme0n1p2 /boot/efi/
mkdir /boot/efi/EFI/zfsbootmenu/
cd /boot/efi/EFI/zfsbootmenu/
wget https://github.com/zbm-dev/zfsbootmenu/releases/download/v2.3.0/zfsbootmenu-release-x86_64-v2.3.0-vmlinuz.EFI -O zfsbootmenu.efi
cd /boot/efi/loader/entries
nano zfsbootmenu.conf
title ZFSBootMenu
efi /EFI/zfsbootmenu/zfsbootmenu.efi
Finally to also set the commandline options as applied to host (adjust to match host) - set the following zfs attribute:
(the middle and final bit "rpool/ROOT/pve-1
" is your dataset - use "zfs list
" and use the one where your root is mounted)
zfs set org.zfsbootmenu:commandline="root=ZFS=rpool/ROOT/pve-1 boot=zfs amd_iommu=on iommu=pt pcie_acs_override=downstream,multifunction" rpool/ROOT/pve-1