On Thu, Jun 24, 2021 at 11:33:53AM +0800, Rocco Yue wrote: > On Wed, 2021-06-23 at 19:19 +0200, Greg KH wrote: > On Wed, Jun 23, 2021 at 07:34:49PM +0800, Rocco Yue wrote: > >> This patch add the definition of ARPHRD_PUREIP which can for > >> example be used by mobile ccmni device as device type. > >> ARPHRD_PUREIP means that this device doesn't need kernel to > >> generate ipv6 link-local address in any addr_gen_mode. > >> > >> Signed-off-by: Rocco Yue <rocco.yue@xxxxxxxxxxxx> > >> --- > >> include/uapi/linux/if_arp.h | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/include/uapi/linux/if_arp.h b/include/uapi/linux/if_arp.h > >> index c3cc5a9e5eaf..4463c9e9e8b4 100644 > >> --- a/include/uapi/linux/if_arp.h > >> +++ b/include/uapi/linux/if_arp.h > >> @@ -61,6 +61,7 @@ > >> #define ARPHRD_DDCMP 517 /* Digital's DDCMP protocol */ > >> #define ARPHRD_RAWHDLC 518 /* Raw HDLC */ > >> #define ARPHRD_RAWIP 519 /* Raw IP */ > >> +#define ARPHRD_PUREIP 520 /* Pure IP */ > > > > In looking at the patches, what differs "PUREIP" from "RAWIP"? It seems > > Thanks for your review. > > The difference between RAWIP and PUREIP is that they generate IPv6 > link-local address and IPv6 global address in different ways. > > RAWIP: > ~~~~~~ > In the ipv6_generate_eui64() function, using RAWIP will always return 0, > which will cause the kernel to automatically generate an IPv6 link-local > address in EUI64 format and an IPv6 global address in EUI64 format. > > PUREIP: > ~~~~~~~ > After this patch set, when using PUREIP, kernel doesn't generate IPv6 > link-local address regardless of which IN6_ADDR_GEN_MODE is used. > > @@ static void addrconf_dev_config(struct net_device *dev) > + if (dev->type == ARPHRD_PUREIP) > + return; > > And after recving RA message, kernel iterates over the link-local address > that exists for the interface and uses the low 64bits of the link-local > address to generate the IPv6 global address. > The general process is as follows: > ndisc_router_discovery() -> addrconf_prefix_rcv() -> ipv6_generate_eui64() -> ipv6_inherit_eui64() Thanks for the explaination, why is this hardware somehow "special" in this way that this has never been needed before? thanks, greg k-h
