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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 0C72BC49EA5 for ; Thu, 24 Jun 2021 13:06:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E33E9613F7 for ; Thu, 24 Jun 2021 13:06:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230046AbhFXNIb (ORCPT ); Thu, 24 Jun 2021 09:08:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:47386 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229940AbhFXNIb (ORCPT ); Thu, 24 Jun 2021 09:08:31 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D974C613C3; Thu, 24 Jun 2021 13:06:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624539971; bh=X5fgruXZAH6/dwtIj9BUqyJ6jlUiiRQEvoljwULOpAw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OGYINAbuGasSG7nLZAa1F5HYrm1MRw/U0QA6imTs9s2BE2lPupOdkJkq0gZ87x0Sb yesHqPbqTj80zcQ+MmgtI5bRE7sFF0bQV4SBJdQRyd99mOxV4POTAfrCs9pMok1y/Q M8IzFW4pQrZMldEaFQlwECzz5es9sGGbKy5izkaY= Date: Thu, 24 Jun 2021 15:06:09 +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: <20210624122435.11887-1-rocco.yue@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210624122435.11887-1-rocco.yue@mediatek.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Jun 24, 2021 at 08:24:35PM +0800, Rocco Yue wrote: > On Thu, 2021-06-24 at 11:04 +0200, Greg KH wrote: > On Thu, Jun 24, 2021 at 02:13:10PM +0800, Rocco Yue wrote: > >> On Thu, 2021-06-24 at 07:29 +0200, Greg KH wrote: > >>> > >>> Thanks for the explaination, why is this hardware somehow "special" in > >>> this way that this has never been needed before? > >>> > >>> thanks, > >>> > >>> greg k-h > >>> > >> > >> Before kernel-4.18, RAWIP was the same as PUREIP, neither of them > >> automatically generates an IPv6 link-local address, and the way to > >> generate an IPv6 global address is the same. > >> > >> After kernel-4.18 (include 4.18 version), the behavior of RAWIP had > >> changed due to the following patch: > >> @@ static int ipv6_generate_eui64(u8 *eui, struct net_device *dev) > >> + case ARPHRD_RAWIP: > >> + return addrconf_ifid_rawip(eui, dev); > >> } > >> return -1; > >> } > >> > >> the reason why the kernel doesn't need to generate the link-local > >> address automatically is as follows: > >> > >> In the 3GPP 29.061, here is some description as follows: > >> "in order to avoid any conflict between the link-local address of > >> MS and that of the GGSN, the Interface-Identifier used by the MS to > >> build its link-local address shall be assigned by the GGSN. The GGSN > >> ensures the uniqueness of this Interface-Identifier. Then MT shall > >> then enforce the use of this Interface-Identifier by the TE" > >> > >> In other words, in the cellular network, GGSN determines whether to > >> reply to the Router Solicitation message of UE by identifying the > >> low 64bits of UE interface's ipv6 link-local address. > >> > >> When using a new kernel and RAWIP, kernel will generate an EUI64 > >> format ipv6 link-local address, and if the device uses this address > >> to send RS, GGSN will not reply RA message. > >> > >> Therefore, in that background, we came up with PUREIP to make kernel > >> doesn't generate a ipv6 link-local address in any address generate > >> mode. > > > > Thanks for the better description. That should go into the changelog > > text somewhere so that others know what is going on here with this new > > option. > > > > Does changelog mean adding these details to the commit message ? Yes please. > > And are these user-visable flags documented in a man page or something > > else somewhere? If not, how does userspace know about them? > > > > There are mappings of these device types value in the libc: > "/bionic/libc/kernel/uapi/linux/if_arp.h". > userspace can get it from here. Yes, they will show up in a libc definition, but where is it documented in text form what the flag does? thanks, greg k-h