Subject: Re: [PATCH net-next v3 2/5] dpll: spec: add support for pin-dpll signal phase offset/adjust

From: Kuba Kicinski <[email-masked]>
Date: Fri, 6 Oct 2023 12:44:57 -0700

On Fri, 6 Oct 2023 18:53:04 +0200 Jiri Pirko wrote:
> Fri, Oct 06, 2023 at 04:55:36PM CEST, [email-masked] wrote:
> >> I'm confused. Didn't you say you'll remove this? If not, my question
> >> from v1 still stands.  
> >
> >Perhaps we should dis-allow setting version in non-genetlink-legacy
> >specs? I thought it may be a useful thing to someone, at some point,
> >but so far the scoreboard is: legit uses: 0, confused uses: 1 :S
> >
> >Thoughts?  
> 
> I don't know what the meaning of version is. I just never saw that being
> touched. Is there any semantics documented for it?
> 
> Kuba, any opinion?

/me switches the first name in From :P

I think it basically predates the op / policy introspection,
and allows people to break backward compat.

drop_monitor bumped to 2 in 2009:

  683703a26e46 ("drop_monitor: Update netlink protocol to include
netlink attribute header in alert message")

which breaks backward compat.

genetlink ctrl went to 2 in 2006:

  334c29a64507 ("[GENETLINK]: Move command capabilities to flags.")

which moves some info around in attrs, also breaks backward compat
if someone depended on the old placement.

ovs did it in 2013:

  44da5ae5fbea ("openvswitch: Drop user features if old user space
attempted to create datapath")

again, breaks backwards compat.

I guess it may still make one day to bump the version for some proto
which has very tight control over the user space. But it hasn't
happened for 10 years.