/** \brief vhost-user interface create request
@param client_index - opaque cookie to identify the sender
@param is_server - our side is socket server
@param sock_filename - unix socket filename, used to speak with frontend
@param use_custom_mac - enable or disable the use of the provided hardware address
/** \brief vhost-user interface create request
@param client_index - opaque cookie to identify the sender
@param is_server - our side is socket server
@param sock_filename - unix socket filename, used to speak with frontend
@param use_custom_mac - enable or disable the use of the provided hardware address