From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [PATCH net-next] ipv6: export IP6_RT_PRIO_* to userland Date: Fri, 09 Nov 2012 10:43:34 +0100 Message-ID: <509CD046.4060302@6wind.com> References: <1352129298-1104-1-git-send-email-nicolas.dichtel@6wind.com> <20121105.120017.1189906314924845791.davem@davemloft.net> <5097F5DF.7040507@6wind.com> <20121105.124305.1002288640313724910.davem@davemloft.net> <5098127A.2040405@6wind.com> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:51740 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751017Ab2KIJnj (ORCPT ); Fri, 9 Nov 2012 04:43:39 -0500 Received: by mail-bk0-f46.google.com with SMTP id jk13so1531480bkc.19 for ; Fri, 09 Nov 2012 01:43:38 -0800 (PST) In-Reply-To: <5098127A.2040405@6wind.com> Sender: netdev-owner@vger.kernel.org List-ID: Le 05/11/2012 20:24, Nicolas Dichtel a =E9crit : > Le 05/11/2012 18:43, David Miller a =E9crit : >> From: Nicolas Dichtel >> Date: Mon, 05 Nov 2012 18:22:39 +0100 >> >>> Le 05/11/2012 18:00, David Miller a =E9crit : >>>> From: Nicolas Dichtel >>>> Date: Mon, 5 Nov 2012 16:28:18 +0100 >>>> >>>>> The kernel uses some default metric when routes are managed. For >>>>> example, a >>>>> static route added with a metric set to 0 is inserted in the kern= el >>>>> with >>>>> metric 1024 (IP6_RT_PRIO_USER). >>>>> It is useful for routing daemons to know these values, to be able= to >>>>> set routes >>>>> without interfering with what the kernel does. >>>>> >>>>> Signed-off-by: Nicolas Dichtel >>>> >>>> But these belong in the libc headers anyways. >>>> >>>> If we haven't provided them for so long, there's no real value of >>>> adding them now. >>>> >>> But how can a daemon know which default values are used? If it want= s >>> to add a route with metric =3D default + x, it should first add it = with >>> metric =3D 0, check the result and then change the metric. >> >> What do we do on the ipv4 side and how do daemons cope in that situa= tion? >> > In IPv4, there is no such default metric. If you add a route with met= ric X, it > remains X in the kernel, even if it's 0. So we need to duplicate these values in the daemon?