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Miller" , "Eric Dumazet" , "Jakub Kicinski" , "Paolo Abeni" , "David Ahern" , "Simon Horman" , "Ido Schimmel" , "Jason Gunthorpe" , "Leon Romanovsky" , "Andrew Lunn" , "Anthony L Nguyen" , "Przemek Kitszel" , "Elad Nachman" , "Saeed Mahameed" , "Tariq Toukan" , "Mark Bloch" , "Petr Machata" , "Edward Cree" , "Maxime Coquelin" , "Alexandre Torgue" , "Arend van Spriel" , "Miri Korenblit" , "Keith Busch" , "Jens Axboe" , "Christoph Hellwig" , "Sagi Grimberg" , "Chaitanya Kulkarni" , "Saurav Kashyap" , "Javed Hasan" , GR-QLogic-Storage-Upstream@marvell.com, "James E . J . Bottomley" , "Martin K. Petersen" , "Nilesh Javali" , "Manish Rangankar" , "Varun Prakash" , "Alexander Viro" , "Christian Brauner" , "Jan Kara" , "David Howells" , "Marc Dionne" , "Trond Myklebust" , "Anna Schumaker" , "Chuck Lever" , "Jeff Layton" , NeilBrown , "Olga Kornievskaia" , "Dai Ngo" , "Tom Talpey" , "Marek Lindner" , "Simon Wunderlich" , "Antonio Quartulli" , "Sven Eckelmann" , "Nikolay Aleksandrov" , "Pablo Neira Ayuso" , "Florian Westphal" , "Phil Sutter" , "Johannes Berg" , "Matthieu Baerts" , "Mat Martineau" , "Geliang Tang" , "Julian Anastasov" , "Aaron Conole" , "Eelco Chaudron" , "Ilya Maximets" , "Allison Henderson" , "Jamal Hadi Salim" , "Jiri Pirko" , "Marcelo Ricardo Leitner" , "Xin Long" , "D. Wythe" , "Dust Li" , "Sidraya Jayagond" , "Wenjia Zhang" , "Mahanta Jambigi" , "Tony Lu" , "Wen Gu" , "Jon Maloy" , "Steffen Klassert" , "Herbert Xu" , "Vikas Gupta" , "Rajashekar Hudumula" , "Justin Chen" , "Bhargava Marreddy" , "Nicolai Buchwitz" , "Florian Fainelli" , "Heiner Kallweit" , "Krzysztof Kozlowski" , "Russell King" , "Yao Zi" , "Yanteng Si" , "Maxime Chevallier" , "Julian Braha" , "Joey Lu" , "Shangjuan Wei" , "Chen-Yu Tsai" , "Inochi Amaoto" , "Lad, Prabhakar" , "Qingfang Deng" , "Greg Kroah-Hartman" , "Eric Biggers" , "Ethan Nelson-Moore" , "Ard Biesheuvel" , "Dmitry Safonov" <0x7f454c46@gmail.com>, "Kuniyuki Iwashima" , "Alyssa Ross" , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, "intel-wired-lan@lists.osuosl.org" , "open list:NETRONOME ETHERNET DRIVERS" , linux-net-drivers@amd.com, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-wireless@vger.kernel.org, brcm80211@lists.linux.dev, brcm80211-dev-list.pdl@broadcom.com, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org, "open list:ETHERNET BRIDGE" , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, mptcp@lists.linux.dev, lvs-devel@vger.kernel.org, dev@openvswitch.org, rds-devel@oss.oracle.com, linux-sctp@vger.kernel.org, linux-s390@vger.kernel.org, "open list:TIPC NETWORK LAYER" Message-Id: <713178ff-0fb2-4f1b-90bc-9841cd42c20e@app.fastmail.com> In-Reply-To: <2256daf4-d03c-4a57-9d72-7a388d823f18@suse.de> References: <20260712013941.4570-1-fmancera@suse.de> <20260712013941.4570-2-fmancera@suse.de> <12ffac6a-649a-4e4a-8d12-0b48171e1d95@app.fastmail.com> <2256daf4-d03c-4a57-9d72-7a388d823f18@suse.de> Subject: Re: [PATCH 01/13 RFC net-next] net: ipv4: introduce CONFIG_IPV4 to decouple the IPv4 stack Content-Type: text/plain Content-Transfer-Encoding: 7bit On Mon, Jul 13, 2026, at 16:00, Fernando Fernandez Mancera wrote: > On 7/12/26 1:01 PM, Arnd Bergmann wrote: >> On Sun, Jul 12, 2026, at 03:38, Fernando Fernandez Mancera wrote: >>> Historically, the IPv4 protocol has been linked to the core INET >>> subsystem. Because shared infrastructure like the TCP/UDP engine, >>> routing or INET hashtables live inside net/ipv4/, it has been impossible >>> to compile a kernel with only IPv6 support. >>> >>> This patch introduces the CONFIG_IPV4 Kconfig symbol, which is set to >>> 'def_bool y' for now. This does not allow to completely disable the >>> IPv4 stack yet but it lays the necessary build-system work for that >>> goal. >> >> I expect this will cause additional (trivial) build regression in the >> next step when randconfig builds run into obscure corner cases, either >> with INET=y IPV4=n IPV6=y or with INET=y IPV4=n IPV6=n. >> >> I can probably give your patch (with IPV4 visible or disabled) an >> early go on the randconfig tree to find these more quickly. >> If I run into regressions, should I just add more 'depends on IPV4', >> or do you have other plans? >> > > Yes, I have a job running randconfig and verifying nothing breaks. If > something breaks and it isn't core networking stack I would just make > the Kconfig symbol depend on IPv4. > > Then later we will have more time to write a dedicate patch so it does > not depend on IPv4. Ok >> Should we have some logic to ensure that at least one of IPV4 or >> IPV6 is enabled? I think this would work >> >> config IPV4 >> bool "The IPv4 protocol" if IPV6 >> default INET >> >> which only allows turning IPV4 off if IPV6 has enabled. >> > > I do wonder, should we? I mean, I didn't try it off but I don't see why > we should not allow a pure L2 system.. I expected a pure L2 system to be CONFIG_ETHERNET=y CONFIG_INET=n. Which user-visible parts of CONFIG_INET would you want keep working when both v4 and v6 are disabled? Arnd