Re: [PATCH net-next v3 11/11] wireguard: netlink: generate netlink code

Asbjørn Sloth Tønnesen
2025-11-20T19:49:42Z

On 11/20/25 12:54 AM, Jason A. Donenfeld wrote:
> On Tue, Nov 18, 2025 at 05:00:45PM -0800, Jakub Kicinski wrote:
>> On Tue, 18 Nov 2025 23:51:37 +0100 Jason A. Donenfeld wrote:
>>> I mean, there is *tons* of generated code in the kernel. This is how it
>>> works. And you *want the output to change when the tool changes*. That's
>>> literally the point. It would be like if you wanted to check in all the
>>> .o files, in case the compiler started generating different output, or
>>> if you wanted the objtool output or anything else to be checked in. And
>>> sheerly from a git perspective, it seems outrageous to touch a zillion
>>> files every time the ynl code changes. Rather, the fact that it's
>>> generated on the fly ensures that the ynl generator stays correctly
>>> implemented. It's the best way to keep that code from rotting.
>>
>> CI checks validate that the files are up to date.
>> There has been no churn to the kernel side of the generated code.
>> Let's be practical.
>
> Okay, it sounds like neither of you want to do this. Darn. I really hate
> having generated artifacts laying around that can be created efficiently
> at compile time. But okay, so it goes. I guess we'll do that.

I generally agree, but given this generates code across the tree, then I
prefer this, as side-effects are more obvious.

To complete Jakub's earlier argument of not complicating everyone's life,
then this code generator is Python-based and depends on yaml and jsonschema.
Even doing compile-time generation for a single family, would elevate those
packages from developer-dependencies to build-dependencies.

> I would like to ask two things, then, which may or may not be possible:
>
> 1) Can we put this in drivers/net/wireguard/generated/netlink.{c.h}
> And then in the Makefile, do `wireguard-y += netlink.o generated/netlink.o`
> on one line like that. I prefer this to keeping it in the same
> directory with the awkward -gen suffix.

Sure, there isn't much consistency across families anyway.