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
