Re: [PATCH 3/3 net-next v4] selftests: net: add test for IPv4 devconf netlink notifications

[Fernando Fernandez Mancera <fmancera@suse.de>]

On 5/15/26 1:24 AM, Jakub Kicinski wrote:
> On Thu, 14 May 2026 11:42:16 +0200 Fernando Fernandez Mancera wrote:
>> On 5/14/26 4:35 AM, Jakub Kicinski wrote:
>>> On Sun, 10 May 2026 10:15:28 +0200 Fernando Fernandez Mancera wrote:
>>>> Introduce a new test, `ipv4_devconf_notify`, to verify that the kernel
>>>> sends the appropriate netlink notifications when IPv4 devconf parameters
>>>> are modified.
>>>>
>>>> Since YNL currently has a bug where it declares an array of u32 values
>>>> instead of the nested attributes expected by the kernel for devconf set
>>>> operations, a temporary hack (`patched_add_attr`) is included to
>>>> pack the netlink attributes correctly.
>>>
>>> Right, YNL doesn't really support the level or weirdness that netconf
>>> requires. Why use YNL? Can't we test this with iproute2?
>>
>> No, AFAIU, iproute2 does not expose devconf settings. The main user of
>> IFLA_INET_CONF are netlink libraries and other userspace tools that
>> heavily rely on netlink operations like NetworkManager, nmstate, nispor,
>> rust-netlink..
> 
> Isn't this ip netconf ?
> 

Oh sorry, I should have clarified it. ip netconf only shows/query them 
but it cannot set them AFAICS.

Usage: ip netconf show [ dev STRING ]

>> FWIW, I plan to fix the YNL side of things so we have this fixed
>> properly.
> 
> If it adds any hacks or new concepts to YNL it's unlikely to
> be accepted :(
> 
>> But I would prefer if this isn't blocked. Another patchset
>> introducing IFLA_INET6_CONF support is also coming.. being able to avoid
>> sysctl usage is quite useful for these userspace tools.
>