From: Rocco Yue <rocco.yue@mediatek.com>
To: 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 20:24:35 +0800 [thread overview]
Message-ID: <20210624122435.11887-1-rocco.yue@mediatek.com> (raw)
In-Reply-To: <YNRKhJB9/K4SKPdR@kroah.com>
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 ?
I am willing do it.
> 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.
But I also failed to find a man page or a description of these
device types.
Thanks,
Rocco
next prev parent reply other threads:[~2021-06-24 12:39 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 11:34 [PATCH 1/4] net: if_arp: add ARPHRD_PUREIP type Rocco Yue
2021-06-23 11:34 ` [PATCH 2/4] net: ipv6: don't generate link local address on PUREIP device Rocco Yue
2021-06-23 11:34 ` [PATCH 3/4] net: dev_is_mac_header_xmit() return false for ARPHRD_PUREIP Rocco Yue
2021-06-23 11:34 ` [PATCH 4/4] drivers: net: mediatek: initial implementation of ccmni Rocco Yue
2021-06-23 17:25 ` Greg KH
2021-06-23 17:31 ` Greg KH
2021-06-24 11:53 ` [PATCH 1/4] net: if_arp: add ARPHRD_PUREIP type Rocco Yue
2021-06-24 12:23 ` Greg KH
2021-06-24 15:55 ` [PATCH 4/4] drivers: net: mediatek: initial implementation of ccmni Rocco Yue
2021-06-24 16:51 ` Greg KH
2021-06-28 7:18 ` Rocco Yue
2021-06-28 9:30 ` Greg KH
2021-06-23 17:19 ` [PATCH 1/4] net: if_arp: add ARPHRD_PUREIP type Greg KH
2021-06-24 3:33 ` Rocco Yue
2021-06-24 5:15 ` David Ahern
2021-06-24 5:31 ` Rocco Yue
2021-06-24 5:29 ` Greg KH
2021-06-24 6:13 ` Rocco Yue
2021-06-24 9:04 ` Greg KH
2021-06-24 12:24 ` Rocco Yue [this message]
2021-06-24 13:06 ` Greg KH
2021-06-25 6:01 ` Rocco Yue
2021-06-24 16:14 ` Dan Williams
2021-06-25 6:04 ` Rocco Yue
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