tftpd/rootfs/tmp/etc/nginx/nginx.conf

worker_processes  1;
events {
    worker_connections  1024;
}

http {
    include                /etc/nginx/mime.types;
    default_type           application/octet-stream;
    sendfile               on;
    keepalive_timeout      65;

    server {
        listen             80;
        root               /data/tftpd;
        autoindex          on;
    }
}