update-grub produces broken grub.cfg with ZFS mirror volume

[Will Rouesnel]

When running update-grub on Xenial with an mirrored ZFS root, broken grub.cfg files are consistently produced due to the root= line being formatted with block devices and a newline inserted.

Specifically I get a line like so:
 linux /ROOT/mint-13@/boot/vmlinuz-4.6.0-040600-generic root=/dev/sdj1
/dev/sdi3 ro nomdmonddf nomdmonisw

The newline is what's included.

[Will Rouesnel (w-rouesnel)]

The problem seems to be that grub-mkconfig doesn't account for grub-probe producing a multiple lines of output with a ZFS root device:

/usr/sbin/grub-probe --target=device /
/dev/sdj1
/dev/sdi3

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nick Niehoff (nniehoff)]

In Eoan a workaround for this seems to be to add head -1 to the following line of /etc/grub.d/10_linux_zfs:

initrd_device=$(${grub_probe} --target=device "${boot_dir}")

to

initrd_device=$(${grub_probe} --target=device "${boot_dir}" | head -1)

This limits the initrd devices to 1, this is only a workaround for this bug

[HARI NARAYAN MAHTO (hnm555)]

install ubuntu. then run boot-repair in terminal to fix this via liveusb then try to reboot system. i fixed this and now i'm able to boot into ubuntu 20.04.

[Brian Murray (brian-murray)]

The Eoan Ermine has reached end of life, so this bug will not be fixed for that release