I'm running Arch Linux, it uses
systemd-modules-load to load modules configured in /etc/rc.conf, but since I use a custom kernel and lts kernel, I had to put all possible modules in that config file (in custom kernel most of those are builtin)
During boot I could see errors from
XX is not implemented or so , for those builtin module.
Is that a bug ? (modprobe builtin_module doesn't print error)