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Subject: Re: [PATCH 1/4] net: if_arp: add ARPHRD_PUREIP type
To:     Rocco Yue <rocco.yue@mediatek.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
References: <YNNtN3cdDL71SiNt@kroah.com>
 <20210624033353.25636-1-rocco.yue@mediatek.com>
From:   David Ahern <dsahern@gmail.com>
Message-ID: <020403ac-0c2a-4ad8-236b-d32e59aef772@gmail.com>
Date:   Wed, 23 Jun 2021 23:15:03 -0600
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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.