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, Rocco
