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Tue, 10 Mar 2026 11:08:34 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 10 Mar 2026 15:08:32 -0300 Message-Id: Subject: Re: [PATCH 00/10 net-next v2] Convert CONFIG_IPV6 to built-in and remove stubs Cc: , , , , , , , To: "Fernando Fernandez Mancera" , From: =?utf-8?b?UmljYXJkbyBCLiBNYXJsacOocmU=?= X-Mailer: aerc 0.21.0-120-g22b95d38161f References: <20260310153506.5181-1-fmancera@suse.de> In-Reply-To: <20260310153506.5181-1-fmancera@suse.de> On Tue Mar 10, 2026 at 12:34 PM -03, Fernando Fernandez Mancera wrote: > Historically, the Linux kernel has supported compiling the IPv6 stack as > a loadable module. While this made sense in the early days of IPv6 > adoption, modern deployments and distributions overwhelmingly either > build IPv6 directly into the kernel (CONFIG_IPV6=3Dy) or disable it > entirely (CONFIG_IPV6=3Dn). The modular IPv6 use-case offers image size > and memory savings for specific setups, this benefit is outweighed by > the architectural burden it imposes on the subsystems on implementation > and maintenance. > > To allow core networking, BPF, Netfilter, and various device drivers to > safely interact with a potentially unloaded IPv6 module, the kernel > relies on indirect call structures like ipv6_stub, ipv6_bpf_stub, and > nf_ipv6_ops, along with dynamic RCU registrations for things like ICMPv6 > senders. > > This patch series addresses this by changing CONFIG_IPV6 from a tristate > to a boolean, enforcing that IPv6 is either built-in or disabled. This > allows us to completely rip out the stub infrastructures and safely > replace them with direct function calls. > > The bloat-o-meter report the following results for m68k, arm64, x86_64 > defconfig. > > m68k (keep on mind that CONFIG_IPV6 is disabled now): > add/remove: 65/938 grow/shrink: 36/254 up/down: 3022/-49692 (-46670) > > arm64: > add/remove: 1251/265 grow/shrink: 81/46 up/down: 448740/-71519 (377221) > > x86_64: > add/remove: 62/98 grow/shrink: 10/39 up/down: 2497/-4357 (-1860) > > All the patches has been independently build tested. With allmodconfig > and allmodconfig + CONFIG_IPV6=3Dn. In addition, net selftest has been ru= n > against them on virtme-ng. > > The series applied as a whole as been tested with allyesconfig and also > allyesconfig + CONFIG_IPV6=3Dn but not all patches has been independently > tested this way. > > This will like need to wait for [1] and [2] to be applied to avoid > conflicts from net tree and rebased in top of them. > > [1] https://lore.kernel.org/netdev/20260307-net-nd_tbl_fixes-v4-0-e2677e8= 5628c@suse.com/ > > [2] https://lore.kernel.org/netdev/20260308032304.1841198-1-kuniyu@google= .com/ > > Fernando Fernandez Mancera (10): > ipv6: convert CONFIG_IPV6 to built-in only and clean up Kconfigs > ipv6: replace IS_BUILTIN(CONFIG_IPV6) with IS_ENABLED(CONFIG_IPV6) > ipv6: remove dynamic ICMPv6 sender registration infrastructure > ipv6: prepare headers for ipv6_stub removal > drivers: net: drop ipv6_stub usage and use direct function calls > ipv4: drop ipv6_stub usage and use direct function calls > net: convert remaining ipv6_stub users to direct function calls > bpf: remove ipv6_bpf_stub completely and use direct function calls > ipv6: remove ipv6_stub infrastructure completely > netfilter: remove nf_ipv6_ops and use direct function calls Using defconfig + tools/testing/selftests/net/config: - All commits build with both IPV6=3Dy and IPV6=3Dn with no problems. - All net selftests report OK on tip commit. Tested-by: Ricardo B. Marli=C3=A8re > > arch/arm64/configs/defconfig | 2 +- > arch/m68k/configs/amiga_defconfig | 45 +------- > arch/m68k/configs/apollo_defconfig | 46 +------- > arch/m68k/configs/atari_defconfig | 45 +------- > arch/m68k/configs/bvme6000_defconfig | 45 +------- > arch/m68k/configs/hp300_defconfig | 47 +------- > arch/m68k/configs/mac_defconfig | 45 +------- > arch/m68k/configs/multi_defconfig | 45 +------- > arch/m68k/configs/mvme147_defconfig | 45 +------- > arch/m68k/configs/mvme16x_defconfig | 45 +------- > arch/m68k/configs/q40_defconfig | 45 +------- > arch/m68k/configs/sun3_defconfig | 45 +------- > arch/m68k/configs/sun3x_defconfig | 45 +------- > drivers/infiniband/Kconfig | 1 - > drivers/infiniband/core/addr.c | 3 +- > drivers/infiniband/hw/ocrdma/Kconfig | 2 +- > drivers/infiniband/sw/rxe/rxe_net.c | 6 +- > drivers/infiniband/ulp/ipoib/Kconfig | 2 +- > drivers/net/Kconfig | 9 -- > drivers/net/ethernet/broadcom/Kconfig | 2 +- > drivers/net/ethernet/chelsio/Kconfig | 2 +- > .../mellanox/mlx5/core/en/rep/neigh.c | 12 ++- > .../ethernet/mellanox/mlx5/core/en/tc_tun.c | 3 +- > .../mellanox/mlx5/core/en/tc_tun_encap.c | 2 +- > .../mellanox/mlx5/core/en_accel/ipsec.c | 1 - > .../net/ethernet/mellanox/mlx5/core/en_rep.c | 1 - > .../net/ethernet/mellanox/mlx5/core/en_tc.c | 1 - > drivers/net/ethernet/mellanox/mlxsw/Kconfig | 1 - > .../ethernet/mellanox/mlxsw/spectrum_router.c | 9 +- > .../ethernet/mellanox/mlxsw/spectrum_span.c | 3 +- > drivers/net/ethernet/netronome/Kconfig | 1 - > .../ethernet/netronome/nfp/flower/action.c | 2 +- > .../netronome/nfp/flower/tunnel_conf.c | 9 +- > drivers/net/ethernet/sfc/tc_counters.c | 2 +- > drivers/net/ethernet/sfc/tc_encap_actions.c | 5 +- > drivers/net/geneve.c | 1 - > drivers/net/gtp.c | 2 +- > drivers/net/ovpn/peer.c | 3 +- > drivers/net/ovpn/udp.c | 3 +- > drivers/net/usb/cdc_mbim.c | 17 +-- > drivers/net/vrf.c | 3 +- > drivers/net/vxlan/vxlan_core.c | 11 +- > drivers/net/vxlan/vxlan_multicast.c | 6 +- > drivers/net/wireguard/socket.c | 3 +- > drivers/net/wireless/intel/ipw2x00/ipw2100.c | 2 +- > drivers/scsi/bnx2fc/Kconfig | 1 - > drivers/scsi/bnx2i/Kconfig | 1 - > drivers/scsi/cxgbi/cxgb3i/Kconfig | 2 +- > drivers/scsi/cxgbi/cxgb4i/Kconfig | 2 +- > fs/dlm/Kconfig | 2 +- > fs/gfs2/Kconfig | 2 +- > include/linux/icmpv6.h | 26 +---- > include/linux/indirect_call_wrapper.h | 2 +- > include/linux/netfilter_ipv6.h | 102 ++---------------- > include/net/ip.h | 5 - > include/net/ip6_fib.h | 34 +++++- > include/net/ip6_route.h | 26 +++++ > include/net/ipv6.h | 12 +++ > include/net/ipv6_stubs.h | 102 ------------------ > include/net/ndisc.h | 38 +++---- > include/net/udp_tunnel.h | 3 +- > net/bridge/Kconfig | 1 - > net/bridge/br_arp_nd_proxy.c | 3 +- > net/bridge/br_netfilter_hooks.c | 12 +-- > net/bridge/br_netfilter_ipv6.c | 7 +- > net/core/filter.c | 70 ++++++------ > net/core/lwt_bpf.c | 10 +- > net/ieee802154/6lowpan/tx.c | 2 +- > net/ipv4/Kconfig | 9 +- > net/ipv4/fib_semantics.c | 11 +- > net/ipv4/icmp.c | 2 +- > net/ipv4/nexthop.c | 21 ++-- > net/ipv4/route.c | 2 +- > net/ipv4/udp.c | 7 +- > net/ipv6/Kconfig | 6 +- > net/ipv6/addrconf.c | 10 +- > net/ipv6/addrconf_core.c | 91 ---------------- > net/ipv6/af_inet6.c | 69 ++---------- > net/ipv6/icmp.c | 6 -- > net/ipv6/ip6_fib.c | 10 +- > net/ipv6/ip6_icmp.c | 46 +------- > net/ipv6/ip6_offload.c | 4 +- > net/ipv6/ip6_output.c | 5 +- > net/ipv6/ip6_udp_tunnel.c | 3 +- > net/ipv6/ndisc.c | 35 +++--- > net/ipv6/netfilter.c | 48 --------- > net/ipv6/route.c | 13 +-- > net/l2tp/Kconfig | 1 - > net/mpls/af_mpls.c | 3 +- > net/netfilter/Kconfig | 8 -- > net/netfilter/core.c | 3 - > net/netfilter/nf_nat_masquerade.c | 21 +--- > net/netfilter/nfnetlink_queue.c | 22 +++- > net/netfilter/utils.c | 1 - > net/openvswitch/actions.c | 3 +- > net/rxrpc/Kconfig | 2 +- > net/sched/sch_frag.c | 4 +- > net/sctp/Kconfig | 1 - > net/tipc/Kconfig | 1 - > net/tipc/udp_media.c | 9 +- > net/xfrm/espintcp.c | 5 +- > net/xfrm/xfrm_nat_keepalive.c | 4 +- > net/xfrm/xfrm_output.c | 3 +- > 103 files changed, 328 insertions(+), 1301 deletions(-) > delete mode 100644 include/net/ipv6_stubs.h