[all variants] Any way to chroot & update-grub without having grub scan drives outside the chroot?

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http://ubuntuforums.org – Hi :) I'm replacing a dying drive from my father's laptop. I've cloned it to a new one, which is native 4k as opposed to the old one being 512B, so I needed to repartition the target drive to align the partitions correctly. Thus, I need to update grub on the new drive. I don't have the laptop (my father lives in another region of the country), so I'm trying to chroot into it and just run update-grub from there. My Ubuntu box has some iSCSI volumes and of course its own Ubuntu installation. All of these are scanned by update-grub, even though none of them appear if I do a df inside the chroo (Hardware)