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Date:   Tue, 17 Aug 2021 18:21:55 +0200
From:   Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>
To:     Guillaume Nault <gnault@redhat.com>
Cc:     James Carlson <carlsonj@workingcode.com>,
        Chris Fowler <cfowler@outpostsentinel.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paul Mackerras <paulus@samba.org>,
        "David S. Miller" <davem@davemloft.net>,
        "linux-ppp@vger.kernel.org" <linux-ppp@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ppp: Add rtnl attribute IFLA_PPP_UNIT_ID for specifying
 ppp unit id
Message-ID: <20210817162155.idyfy53qbxcsf2ga@pali>
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On Tuesday 17 August 2021 18:05:25 Guillaume Nault wrote:
> On Mon, Aug 16, 2021 at 06:23:55PM +0200, Pali Rohár wrote:
> > On Monday 16 August 2021 18:11:14 Guillaume Nault wrote:
> > > Do you have plans for adding netlink support to pppd? If so, is the
> > > project ready to accept such code?
> > 
> > Yes, I have already some WIP code and I'm planning to send a pull
> > request to pppd on github for it. I guess that it could be accepted,
> 
> I guess you can easily use the netlink api for cases where the "unit"
> option isn't specified and fall back to the ioctl api when it is. If
> all goes well, then we can extend the netlink api to accept a unit id.
> 
> But what about the lack of netlink feedback about the created
> interface? Are you restricted to use netlink only when the "ifname"
> option is provided?

Exactly, this is how I wrote my WIP code...

> > specially if there still would be backward compatibility via ioctl for
> > kernels which do not support rtnl API.
> 
> Indeed, I'd expect keeping compatiblitity with old kernels that only
> have the ioctl api to be a must (but I have no experience contributing
> to the pppd project).
> 
> > One of the argument which can be
> > used why rtnl API is better, is fixing issue: atomic creating of
> > interface with specific name.
> 
> Yes, that looks useful.
>