From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0EFBCC49EA5 for ; Thu, 24 Jun 2021 05:29:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1429613E2 for ; Thu, 24 Jun 2021 05:29:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230132AbhFXFbX (ORCPT ); Thu, 24 Jun 2021 01:31:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:49908 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229448AbhFXFbX (ORCPT ); Thu, 24 Jun 2021 01:31:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id CA203613E1; Thu, 24 Jun 2021 05:29:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624512545; bh=CrNTDEASE0hOIuPiLp9bEqtZG5PdJqBwgm5EWk5Moa8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dgkCqd8aSzCz5aPuT31Q+mRsU5exsL1ljJgUFfQi1UaKhFhMNgCPbvd2piVCS2QJD /TxeTOJJI+Kz76WmLScOvrnbQGQPgwft+l+HDUb1zXiHT/iJve3J8w26JMyoe/lt2L 8W1qbhYXfcSDiKszMprXGq2cKMnjyHpJGXMVFcyI= Date: Thu, 24 Jun 2021 07:29:01 +0200 From: Greg KH To: Rocco Yue Cc: "David S . Miller" , Jakub Kicinski , Jonathan Corbet , Hideaki YOSHIFUJI , David Ahern , Matthias Brugger , Felix Fietkau , John Crispin , Sean Wang , Mark Lee , netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, bpf@vger.kernel.org, wsd_upstream@mediatek.com, chao.song@mediatek.com, kuohong.wang@mediatek.com Subject: Re: [PATCH 1/4] net: if_arp: add ARPHRD_PUREIP type Message-ID: References: <20210624033353.25636-1-rocco.yue@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210624033353.25636-1-rocco.yue@mediatek.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Jun 24, 2021 at 11:33:53AM +0800, Rocco Yue wrote: > On Wed, 2021-06-23 at 19:19 +0200, Greg KH wrote: > On Wed, Jun 23, 2021 at 07:34:49PM +0800, Rocco Yue wrote: > >> This patch add the definition of ARPHRD_PUREIP which can for > >> example be used by mobile ccmni device as device type. > >> ARPHRD_PUREIP means that this device doesn't need kernel to > >> generate ipv6 link-local address in any addr_gen_mode. > >> > >> Signed-off-by: Rocco Yue > >> --- > >> include/uapi/linux/if_arp.h | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/include/uapi/linux/if_arp.h b/include/uapi/linux/if_arp.h > >> index c3cc5a9e5eaf..4463c9e9e8b4 100644 > >> --- a/include/uapi/linux/if_arp.h > >> +++ b/include/uapi/linux/if_arp.h > >> @@ -61,6 +61,7 @@ > >> #define ARPHRD_DDCMP 517 /* Digital's DDCMP protocol */ > >> #define ARPHRD_RAWHDLC 518 /* Raw HDLC */ > >> #define ARPHRD_RAWIP 519 /* Raw IP */ > >> +#define ARPHRD_PUREIP 520 /* Pure IP */ > > > > In looking at the patches, what differs "PUREIP" from "RAWIP"? It seems > > Thanks for your review. > > The difference between RAWIP and PUREIP is that they generate IPv6 > link-local address and IPv6 global address in different ways. > > RAWIP: > ~~~~~~ > In the ipv6_generate_eui64() function, using RAWIP will always return 0, > which will cause the kernel to automatically generate an IPv6 link-local > address in EUI64 format and an IPv6 global address in EUI64 format. > > PUREIP: > ~~~~~~~ > After this patch set, when using PUREIP, kernel doesn't generate IPv6 > link-local address regardless of which IN6_ADDR_GEN_MODE is used. > > @@ static void addrconf_dev_config(struct net_device *dev) > + if (dev->type == ARPHRD_PUREIP) > + return; > > And after recving RA message, kernel iterates over the link-local address > that exists for the interface and uses the low 64bits of the link-local > address to generate the IPv6 global address. > The general process is as follows: > ndisc_router_discovery() -> addrconf_prefix_rcv() -> ipv6_generate_eui64() -> ipv6_inherit_eui64() Thanks for the explaination, why is this hardware somehow "special" in this way that this has never been needed before? thanks, greg k-h