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In-Reply-To: <8cac820a181070ac2bad983dc49e4e4e@dev.tdt.de>
From:   Xie He <xie.he.0141@gmail.com>
Date:   Wed, 3 Mar 2021 12:23:24 -0800
Message-ID: <CAJht_ENFd74+MeqYDk4AtipKFcQ3n7WHG-rNL62Z=K3FxWct=A@mail.gmail.com>
Subject: Re: [PATCH net-next RFC v4] net: hdlc_x25: Queue outgoing LAPB frames
To:     Martin Schiller <ms@dev.tdt.de>
Cc:     Jakub Kicinski <kuba@kernel.org>,
        Leon Romanovsky <leon@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Linux X25 <linux-x25@vger.kernel.org>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Krzysztof Halasa <khc@pm.waw.pl>,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org
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On Wed, Mar 3, 2021 at 5:26 AM Martin Schiller <ms@dev.tdt.de> wrote:
>
> On 2021-03-03 00:30, Jakub Kicinski wrote:
> >
> > Hard question to answer, existing users seem happy and Xie's driver
> > isn't upstream, so the justification for potentially breaking backward
> > compatibility isn't exactly "strong".
> >
> > Can we cop out and add a knob somewhere to control spawning the extra
> > netdev? Let people who just want a newer kernel carry on without
> > distractions and those who want the extra layer can flip the switch?
>
> Yes, that would be a good compromise.
> I think a compile time selection option is enough here.
> We could introduce a new config option CONFIG_HDLC_X25_LEGACY (or
> something like that) and then implement the new or the old behavior in
> the driver accordingly.
>
> A switch that can be toggled at runtime (e.g. via sethdlc) would also be
> conceivable, but I don't think this is necessary.

Yes, I think adding a new config option would be a good way. Thank you both!!