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. And are these user-visable flags documented in a man page or something else somewhere? If not, how does userspace know about them? thanks, greg k-h
