netdev - Re: [PATCH] net: ipv6: don't generate link-local address in any addr_gen

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Message-ID: <46a9dbf2-9748-330a-963e-57e615a15440@gmail.com>
Date:   Wed, 30 Jun 2021 22:41:26 -0600
From:   David Ahern <dsahern@...il.com>
To:     Rocco Yue <rocco.yue@...iatek.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, wsd_upstream@...iatek.com,
        rocco.yue@...il.com, chao.song@...iatek.com,
        kuohong.wang@...iatek.com, zhuoliang.zhang@...iatek.com
Subject: Re: [PATCH] net: ipv6: don't generate link-local address in any
 addr_gen_mode

On 6/30/21 9:39 PM, Rocco Yue wrote:
> On Wed, 2021-06-30 at 21:03 -0600, David Ahern wrote:
> On 6/30/21 7:59 PM, Rocco Yue wrote:
>>> This patch provides an ipv6 proc file named
>>> "disable_gen_linklocal_addr", its absolute path is as follows:
>>> "/proc/sys/net/ipv6/conf/<iface>/disable_gen_linklocal_addr".
>>>
>>> When the "disable_gen_linklocal_addr" value of a device is 1,
>>> it means that this device does not need the Linux kernel to
>>> automatically generate the ipv6 link-local address no matter
>>> which IN6_ADDR_GEN_MODE is used.
>>>
>>
>> doesn't this duplicate addr_gen_mode == 1 == IN6_ADDR_GEN_MODE_NONE?
>>
> 
> Hi David,
> 
> Thanks for your review.
> 
> This patch is different with IN6_ADDR_GEN_MODE_NONE.
> 
> When the addr_gen_mode == IN6_ADDR_GEN_MODE_NONE, the Linux kernel
> doesn't automatically generate the ipv6 link-local address.
> 

...

> 
> After this patch, when the "disable_gen_linklocal_addr" value of a device
> is 1, no matter in which addr_gen_mode, the Linux kernel will not automatically
> generate an ipv6 link-local for this device.
> 

those 2 sentences are saying the same thing to me.

for your use case, why is setting addr_gen_mode == 1 for the device not
sufficient?