## deploying to SD card
- build a toplevel config: `nix build '.#hostSystems.moby'`
- mount a system:
  - `mkdir -p root/{nix,boot}`
  - `mount /dev/sdX1 root/boot`
  - `mount /dev/sdX2 root/nix`
- copy the config:
  - `sudo nix copy --no-check-sigs --to root/ $(readlink result)`
    - nix will copy stuff to `root/nix/store`
- install the boot files:
  - `sudo /nix/store/sbwpwngjlgw4f736ay9hgi69pj3fdwk5-extlinux-conf-builder.sh -d ./root/boot -t 5 -c $(readlink ./result)`
    - extlinux-conf-builder can be found in `/run/current-system/bin/switch-to-configuration`