• Late 2013 MacBook Pro Retina
    • 16gb RAM, no swap space enabled
    • aftermarket 2TB SSD
  • Brand new Thunderbolt to Ethernet adapter


  • Fresh install of Ubuntu Server 22.04.3, with GNU/Linux 5.15.0-84-generic x86_64 kernel
  • No other operating systems on machine


This used to work. These problems are new, after recently completely wiping and reinstalling the system, and using a brand new Thunderbolt to Ethernet adapter (old one seems to have died).

The issue:

When booting the machine, with ethernet connected via the Thunderbolt/Ethernet adapter, I'm immediately greeted with an error stating

Error: out of memory
Press any key to continue

Which is followed by a kernel panic stating

VFS: cannot open root device "mapper/vg0-lv--root" or unknown-block(0,0): error -6
Please append a correct "root=" boot option, here are the available partitions:
Kernel panic - not syncing: VFS: unable to mount root fs on unknown-block(0,0)

See the screenshot for the complete error.

Kernel panic

It is only the dongle being plugged in that causes this error. Meaning, the error occurs even when the dongle is plugged in, but no ethernet cord is plugged into it.

The fun part:

The computer boots normally in both of the following scenarios:

  1. The Thunderbolt/Ethernet adapter is unplugged.
  2. I hold down the "option" key at startup, which brings up the (MacBook) screen for choosing which drive to boot from (in this case, there's only one). Selecting the "EFI Boot" device then boots it normally.

Attempts to fix:

  • Editing /etc/initramfs-tools/initramfs.conf, setting MODULES=dep, COMPRESS=xz, then doing sudo update-initramfs -c -k all && sudo update-grub.

I'm not really sure what else to do.

1 Answer 1


I'd say the dongle also brings up a block device, that the computer tries to unsuccessfully boot from.

Probably by then the drive mapping is no longer correct for your lvm.

When you use the option key it you actually avoid booting from it.

You could try to:

  • force EFI boot (not sure if that can be done on your hardware)
  • configure LVM to use UUID instead of device names
  • check if the dongle is brought up with a disk device, if so, you could even setup EFI/Grub on it

If nothing works, it could help to add more information to the question, such as the exact Thunderbolt/Ethernet adapter model and the lines preceding LVM in a normal boot.

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