UEFI + LUKS + NVMe can be fun

Recently I get a new laptop at work. I finally wanted to make my dream come true and install Gentoo Linux on it. I’ve installed Gentoo already a few times so this wasn’t a big deal. Installing Gentoo is actually an awesome experience. I learnt so much when doing it for the first time. This time, everything went fine until I decided to install bootloader and boot the thing.

So what went wrong?

Legacy boot did not work.

I have no idea why. (How can I debug this actually?) I suspect that grub did not play well with the NVMe SSD.

Onto UEFI then!

I was actually glad this happened because I could finally boot with UEFI. I’ve never tried UEFI.

Except that it was so hard to make it work (mostly due to lack of knowledge on my side).

Lessons learnt

Here’s what went wrong for me, so you can learn from my mistakes:

  1. Please follow the official documentation.

  2. Your USB stick needs to boot from UEFI.
    The reason for this is that once you boot from UEFI, there will be a set of EFI variables exported via /sys/firmware/efi which are needed when installing grub.

  3. Gentoo LiveDVD is old.
    I write this in 2018 and last build of Gentoo LiveDVD is from 2016. 2016 kernel wasn’t able to mount my XFS filesystem made by 2018 kernel. (What was I thinking, right?)

  4. How do I make an USB stick UEFI bootable?
    This one is fairly easy:

    1. Download latest Fedora Workstation ISO.
    2. Modify the ISO in-place so it’s UEFI-bootable from USB stick: isohybrid -u Fedora-Workstation-Live-x86_64-28-1.1.iso.
    3. Put it on the stick: sudo dd if=Fedora-Workstation-Live-x86_64-28-1.1.iso status=progress of=/dev/<USB_STICK> bs=4M.
  5. grub-mkconfig or grub-install spits errors and can’t find the encrypted root.

    # grub-install /dev/nvme0n1
    Installing for i386-pc platform.
     /run/lvm/lvmetad.socket: connect failed: No such file or directory
     Volume group "crypt_root" not found
     Cannot process volume group crypt_root
     Volume group "crypt_root" not found
     Cannot process volume group crypt_root
    grub2-install: error: disk `lvm/crypt_root' not found.
    

    First make LVM available in the chroot environment. (Thanks to this comment.)

    $ mkdir /mnt/gentoo/run/lvm
    $ mount --bind /run/lvm /mnt/gentoo/run/lvm
    

    And then make sure that your grub is compiled with support for device-mapper.

    $ cat /etc/portage/package.use
    sys-boot/grub device-mapper
    
  6. Initramfs can’t detect the NVMe disk, sorry.
    I had to recompile the kernel and changed NVMe support to be directly included in the kernel (instead of being in a kernel module).

  7. Initramfs doesn’t invoke cryptsetup…
    …and errors out that it cannot find the root device.
    The issue for me was that I specified incorrect parameters on kernel command line (via /etc/default/grub).
    Most of the documentation mentions cryptdevice while only this document mentions crypt_root. And that one is correct:

    GRUB_CMDLINE_LINUX="crypt_root=UUID=2cc34ffc-adff-4f4e-b228-40b785677e4c"
    

Happy hacking.

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