Re: [PATCH bpf] selftests/bpf: Support when CONFIG_VXLAN=m

["Alexis Lothoré" <alexis.lothore@bootlin.com>]

Hi Alan,

On Fri Jan 16, 2026 at 10:32 AM CET, Alan Maguire wrote:
> On 16/01/2026 08:30, Alexis Lothoré wrote:
>> Hello,
>> 
>> On Thu Jan 15, 2026 at 5:34 PM CET, Alan Maguire wrote:
>>> If CONFIG_VXLAN is 'm', struct vxlanhdr will not be in vmlinux.h.
>>> Add a ___local variant to support cases where vxlan is a module.
>> 
>> Just a naive question: for ebpf selftests, aren't we assuming a
>> dependency on a "fixed" kernel configuration (ie
>> tools/testing/selftests/bpf/{config,config.vm,config.<arch}), which
>> enables most of the features as built-in ? 
>> 
>
> It's a good question - my take here is that we also need to remember 
> that most folks interactions with BPF happen via distro kernels. Most distros 
> tend to modularize their configs more extensively, and they also want to use 
> the BPF selftests to qualify the particular config combination they have
> so that they can be sure that users have a good BPF experience.
> Often issues arise from this, and distro folks either report or post
> fixes. This is all good, so if the only cost is a bit more flexibility
> in the test environment, I'd say it's well worth supporting that. In
> particular blockers to selftests compilation cause problems for this
> process.
>
> There are of course cases where having a very old toolchain or a highly
> incompatible configuration that aren't supportable, but in general where there
> is low-hanging fruit in making tests a bit more flexible, it's worth doing I 
> think.

With a bit of delay: ok, thanks for your input. To clarify, my point was
not really about challenging your change but rather that I was not sure
about the policy here; supporting only the CI selftests configuration,
VS supporting other kernel configurations like distro configs (at the
cost of duplicating a bit kernel data strutures definitions).

Thanks,

Alexis

-- 
Alexis Lothoré, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com