From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephan Gatzka Subject: Re: IPv6 over Firewire Date: Fri, 21 Dec 2012 19:39:54 +0100 Message-ID: <50D4ACFA.6040901@gmail.com> References: <50D49659.1000101@gmail.com> <50D4A219.7080807@linux-ipv6.org> Reply-To: stephan.gatzka@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net To: YOSHIFUJI Hideaki Return-path: Received: from mail-bk0-f47.google.com ([209.85.214.47]:42293 "EHLO mail-bk0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751260Ab2LUSj6 (ORCPT ); Fri, 21 Dec 2012 13:39:58 -0500 Received: by mail-bk0-f47.google.com with SMTP id j4so2557462bkw.20 for ; Fri, 21 Dec 2012 10:39:57 -0800 (PST) In-Reply-To: <50D4A219.7080807@linux-ipv6.org> Sender: netdev-owner@vger.kernel.org List-ID: > If you are talking about how to build NS/NA/RS/Redirect messages, you > can just use ndisc_opt_addr_space() and ndisc_fill_addr_option() here. Thanks, these functions are certainly helpful. But ndisc_opt_addr_space() calculates the required space from dev->addr_len and ndisc_addr_option_pad(dev->type). The latter is 0 for IEEE1394 (firewire). So the required option space just comes from dev->addr_len, which is 8 for firewire, resulting in an option address space of 16 (2 octets). But rfc3146 requires an option address space of 3 octets. So my main question is if in such a situation the best is to reserve additional skb tail room using needed_tailroom in struct netdevice. This directly affects the memory allocated in ndisc_build_skb(). Regards, Stephan