Subject: Re: [RFC v2 2/4] net: enables interface option to skip IP

From: Dan Williams <[email-masked]>
Date: Mon, 24 Feb 2014 12:22:00 -0600

On Thu, 2014-02-20 at 12:31 -0800, Luis R. Rodriguez wrote:
> On Wed, Feb 19, 2014 at 4:56 PM, Dan Williams <[email-masked]> wrote:
> > Note that there isn't yet a disable_ipv4 knob though, I was
> > perhaps-too-subtly trying to get you to send a patch for it, since I can
> > use it too :)
> 
> Sure, can you describe a little better the use case, as I could use
> that for the commit log. My only current use case was the xen-netback
> case but Zoltan has noted a few cases where an IPv4 or IPv6 address
> *could* be used on the backend interfaces (which I'll still poke as
> its unclear to me why they have 'em).

My use-case would simply be to have an analogue for the disable_ipv6
case.  In the future I expect more people will want to disable IPv4 as
they move to IPv6.  If you don't have something like disable_ipv4, then
there's no way to ensure that some random program or something doesn't
set up IPv4 stuff that you don't want.

Same thing for IPv6; some people really don't want IPv6 enabled on an
interface no matter what; they don't want an IPv6LL address assigned,
they don't want kernel SLAAC, they want to ensure that *nothing*
IPv6-related gets done for that interface.  The same can be true for
IPv4, but we don't have a way of doing that right now.

Dan