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From:   Rocco Yue <rocco.yue@mediatek.com>
To:     David Ahern <dsahern@gmail.com>,
        Greg KH <gregkh@linuxfoundation.org>
CC:     "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
        Sean Wang <sean.wang@mediatek.com>,
        Mark Lee <Mark-MC.Lee@mediatek.com>, <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>, Rocco Yue <rocco.yue@mediatek.com>
Subject: Re: [PATCH 1/4] net: if_arp: add ARPHRD_PUREIP type
Date:   Thu, 24 Jun 2021 13:31:59 +0800
Message-ID: <20210624053159.22345-1-rocco.yue@mediatek.com>
In-Reply-To: <020403ac-0c2a-4ad8-236b-d32e59aef772@gmail.com>
References: <020403ac-0c2a-4ad8-236b-d32e59aef772@gmail.com>
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On Wed, 2021-06-23 at 23:15 -0600, David Ahern wrote:
On 6/23/21 9:33 PM, Rocco Yue wrote:
>> 
>> 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()
>> 
> 
> please add that to the commit message.

Thanks for your reminding, will do.

Thanks,
Rocco