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From:   Lorenzo Colitti <lorenzo@google.com>
Date:   Mon, 13 Sep 2021 18:38:06 +0900
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Subject: Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen_mode
To:     Mark Smith <markzzzsmith@gmail.com>
Cc:     David Ahern <dsahern@gmail.com>,
        Rocco Yue <rocco.yue@mediatek.com>,
        "David S . Miller" <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Linux NetDev <netdev@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
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        rocco.yue@gmail.com, chao.song@mediatek.com,
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On Mon, Sep 13, 2021 at 12:47 AM Mark Smith <markzzzsmith@gmail.com> wrote:
> This is all going in the wrong direction. Link-local addresses are not
> optional on an interface, all IPv6 enabled interfaces are required to
> have one:

The original patch did indeed disable the generation of the link-local
address, but that patch was rejected. It sounds like the right
approach here is to provide two new addressing modes:

IN6_ADDR_GEN_MODE_RANDOM_LL_TOKEN
IN6_ADDR_GEN_MODE_STABLE_PRIVACY_LL_TOKEN

which would form the link-local address from the token passed in via
IFLA_INET6_TOKEN, but would form non-link-local addresses (e.g.,
global addresses) via the specified means (either random or stable
privacy). I haven't looked at how to do that yet though.