Re: [PATCH dpdk] net: ipv6 link local compliance with rfc 4291

["Robin Jarry" <rjarry@redhat.com>]

Stephen Hemminger, Nov 14, 2025 at 17:05:
> On Fri, 14 Nov 2025 11:57:53 +0100
> Robin Jarry <rjarry@redhat.com> wrote:
>
>> diff --git a/app/test/test_net_ip6.c b/app/test/test_net_ip6.c
>> index cfc550940306..e4642c9a39d9 100644
>> --- a/app/test/test_net_ip6.c
>> +++ b/app/test/test_net_ip6.c
>> @@ -160,7 +160,7 @@ test_ipv6_llocal_from_ethernet(void)
>>  {
>>  	const struct rte_ether_addr local_mac = {{0x04, 0x7b, 0xcb, 0x5c, 0x08, 0x44}};
>>  	const struct rte_ipv6_addr local_ip =
>> -		RTE_IPV6(0xfe80, 0, 0, 0, 0x047b, 0xcbff, 0xfe5c, 0x0844);
>> +		RTE_IPV6(0xfe80, 0, 0, 0, 0x067b, 0xcbff, 0xfe5c, 0x0844);
>>  	struct rte_ipv6_addr ip;
>
> Reading the kernel source there is also special handling to include device
> id into link local address. This is to handle corner case where multiple network
> cards have same hardware MAC address.
>
> Perhaps DPDK should roll port id into link local address?

We discussed about this but it would break the API since you would need
to pass an additional parameter to this function.

And also, I couldn't find anything in the RFC that describes what the
kernel does with device IDs. Nothing mentions if the device id should be
big or little endian, etc.

I don't mind changing the API though but it seems very opinionated.

-- 
Robin

> Contest void where prohibited by law.