boot zfs root filesystem on grub

from here

For some reason, grub was broken. I need to be able to boot my linux from GRUB shell

set root=(hd0,gptXXX)
linux /BOOT/ubuntu_YYY/@/vmlinuz root=ZFS=rpool/ROOT/ubuntu_YYY boot=zfs
initrd /BOOT/ubuntu_YYY/@/initrd.img
boot

the gptXXX i need to search around for a file until I found the /BOOT directory