From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse Subject: Re: [patch 4/4] Configure out IGMP support Date: Mon, 04 Aug 2008 14:53:16 +0100 Message-ID: <1217857996.3454.622.camel@pmac.infradead.org> References: <20080731092703.661994657@free-electrons.com> <20080731093221.565015353@free-electrons.com> <1217619715.3454.488.camel@pmac.infradead.org> <20080804144807.6b2374d9@surf> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20080804144807.6b2374d9@surf> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="iso-8859-1" To: Thomas Petazzoni Cc: linux-kernel@vger.kernel.org, linux-embedded@vger.kernel.org, michael@free-electrons.com, Matt Mackall , netdev@vger.kernel.org, davem@davemloft.net, akpm@linux-foundation.org On Mon, 2008-08-04 at 14:48 +0200, Thomas Petazzoni wrote: > Le Fri, 01 Aug 2008 20:41:55 +0100, > David Woodhouse a =C3=A9crit : >=20 > > The config option probably lives in net/Kconfig, not init/Kconfig. >=20 > Yes, it could. But AFAIK, until now, all CONFIG_EMBEDDED-related > options have been put in init/Kconfig. But if it's preferred, I can o= f > course change the patch to move the config option to net/Kconfig. It clearly lives in net/Kconfig. > > And please could you make it clear how this interacts with > > IP_MULTICAST? > >=20 > > We already have a CONFIG_IP_MULTICAST option, for which the help te= xt > > says "For more people, it's safe to say N'. And I think it defaults= to > > that too. What more does CONFIG_IGMP remove? It's not made clear by > > the help text. >=20 > The interaction of IGMP support with CONFIG_IP_MULTICAST is fairly > unclear to me. >=20 > A large portion of igmp.c is already under #ifdef CONFIG_IP_MULTICAST= : > all the igmp_*() functions, amongst which is igmp_rcv(), referenced i= n > igmp_protocol in net/ipv4/af_inet.c, which is compiled-out > when !CONFIG_IP_MULTICAST. >=20 > All the proc-related code at the end of the file is only conditionnal= y > compiled on CONFIG_PROC_FS, but seems to in fact be only used if both > CONFIG_IP_MULTICAST and CONFIG_PROC_FS are selected: > igmp_mc_proc_init() in net/ipv4/ip_output.c is only called when > CONFIG_IP_MULTICAST and CONFIG_PROC_FS are selected. >=20 > Besides that, it's unclear to me why the ip_mc_*() functions are usef= ul > when !CONFIG_IP_MULTICAST, but I'm probably missing something.=20 Most of them aren't, as far as I can tell.=20 > They are used to implement setsockopt-operations related to multicast= , > hooks for the routing code to handle multicast-related traffic, etc. I wonder if those options should return errors now, rather than silentl= y failing but returning zero. Or maybe that _would_ cause a stock build o= f ntpd to fail? Not that it really matters if it _does_, though. It sounds like 'CONFIG_IGMP' is a bad name for the option, too -- and the help text is similarly misleading. I think you need to work out how it all fits together with CONFIG_IP_MULTICAST, fix it up, and resubmit it. --=20 David Woodhouse Open Source Technology Centr= e David.Woodhouse@intel.com Intel Corporatio= n