I believe my issue is the same and that I could narrow it down more. The `mount --bind /nixos/nix /nix` command works, but if I put a line `"/nixos/nix /nix bind defaults"` in `/etc/fstab`, then mount will instead fail with: `mount: /nix: unknown filesystem type 'bind'.` If instead in fstab I use type `none` and put `bind` in the options, then `mount /nix` works at the command-line but interestlingly `guix system reconfigure guix-config.scm` still fails with: ``` guix system: warning: exception caught while executing 'start' on service 'file-system-/nix': In procedure mount: mount "/nixos/nix" on "///nix": No such device guix system: warning: some services could not be upgraded ``` Below is the `file-systems` definition of my `guix-config.scm`, in an attempt to share the `/nix` directory of my NixOS installation with GuixSD, just like I share the /guix directory of my GuixSD installation with NixOS: ``` (file-systems (append (let* ((boot (file-system ;;(uuid "C1D9-0574") (device "/dev/nvme0n1p1") (mount-point "/boot") (type "vfat"))) (root (file-system ;;(device "/dev/mapper/yew-guix") (device (uuid "43f7ca3e-c107-4f15-9756-5d3cbacad0a0")) (mount-point "/") (type "btrfs") #;(flags '(no-atime)) (options "compress=zstd") (dependencies mapped-devices))) (home (file-system ;;(device "/dev/yew/home") (device (uuid "a3602532-3527-4afc-9b40-5d01c58b5aa8")) (mount-point "/home") (type "ext4") (dependencies mapped-devices))) (nixos (file-system (device (uuid "ab3d691b-227a-4a05-a084-6928abbf0959")) (mount-point "/nixos") (type "ext4") (dependencies mapped-devices))) (nix (file-system (device "/nixos/nix") (mount-point "/nix") ;;(type "bind") ;; fails both at CLI and during reconfigure (type "none") (option "bind") ;; CLI OK, reconfigure FAIL (dependencies (list nixos))))) (append (list boot root home nixos nix) %base-file-systems)))) ``` Note that neither bind nor none appear in `/proc/filesystem` nor in `/run/booted-system/kernel/lib/modules/5.13.8/kernel/fs` — but then neither do they on NixOS and yet it all works there.