yeah, i’ve built an iso using archiso (https://wiki.archlinux.org/title/Archiso, https://github.com/archlinux/archiso). i’m running the 2 modprobe commands while booted into that iso (the live environment).

i have the following packages installed on the live iso when building that image:

• arch-install-scripts
• base
• base-devel
• bind
• btrfs-progs
• cryptsetup
• dosfstools
• dracut
• edk2-shell
• efibootmgr
• git
• gptfdisk
• inetutils
• libfido2
• linux-firmware
• linux-zen
• linux-zen-headers
• lvm2
• man
• memtest86+
• memtest86±efi
• net-tools
• parted
• thin-provisioning-tools
• usbutils
• util-linux
• vim
• wge

my next steps would normally be

cryptsetup -v luksFormat /dev/vda2

which asks for a passphrase, creates a key in slot 0, and seems to succeed in encrypting the partition.

cryptsetup luksOpen /dev/vda2 map-root

this asks for the passphrase to unlock, but gives the following response:

device-mapper: reload ioctl on map-root (253:0) failed: Invalid argument

and then my formatting step

mkfs.btrfs -f -L "fs-root-btrfs" /dev/mapper/map-root

clearly doesn’t work.

“pacman -Q cryptsetup” yields “cryptsetup 2.8.6-1”

“uname -a” yields

Linux larch.domain.net 7.1.3-zen1-2-zen #1 ZEN SMP PREEMPT_DYNAMIC Thu, 09 Jul 2026 20:39:38 +0000 x86_64 GNU/Linux

i initially tried this on my laptop, bc i didn’t expect any trouble. but i’m working with a libvirt virtual machine now until i figure out the issue.