emerge -avt debootstrap kexec-tools dosfstools nbd[netlink] pigz pv pyudev pyyaml syslinux wireless-tools
Enable the stiefelsystem system-gentoo module!
Your Gentoo needs an initrd built with dracut with the following modules:
dracut-systemd- use systemd as initrd drivernetwork-manager- bring up the stiefel network via networkmanager- don't use
systemd-networkd- it does not connect the nbd yet (netrootis ignored?)
If your nbd-client does not have netlink support, it will be killed when your initrd switches root to the on-network block device, and then make the root fs unavailable. Hours on debugging were invested why this happens (because nbd-client should not be killed if it has argv[0][0] == '@'), but with netlink it survives the root switch.