Conforme indicado na seção "uso", -p
irá ignorar montagens pseudo-FS (tmpfs, AutoFS e outras):
usage: genfstab [options] root
Options:
-L Use labels for source identifiers (shortcut for -t LABEL)
-p Avoid printing pseudofs mounts (default behavior)
-t TAG Use TAG for source identifiers
-U Use UUIDs for source identifiers (shortcut for -t UUID)-h Print this help message
genfstab generates output suitable for addition to an fstab file based on the devices mounted under the mountpoint specified by the given root.
Você pode verificar os detalhes em seu código-fonte: genfstab.in - arch-install -scripts.git | Repositório oficial arch-install-scripts