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() > to be the same to me. If they are different, where is that documented? > > thanks, > > greg k-h I tried to find corresponding documents about other device types, but I am sorry I didn't find it. If it is needed, I am willing to provide. Thanks, Rocco
