[PATCH 1/4] net: if_arp: add ARPHRD_PUREIP type
gregkh at linuxfoundation.org
Wed Jun 23 22:29:01 PDT 2021
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 at mediatek.com>
> >> ---
> >> 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.
> 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.
> 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?
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