Re: [PATCH v2 5/5] isdn: move capi drivers to staging

From: Arnd Bergmann <arnd@arndb.de>
To: Thomas Jarosch <thomas.jarosch@intra2net.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Networking <netdev@vger.kernel.org>,
	Tilman Schmidt <tilman@imap.cc>,
	Karsten Keil <isdn@linux-pingi.de>,
	gigaset307x-common@lists.sourceforge.net,
	Marcel Holtmann <marcel@holtmann.org>,
	Paul Bolle <pebolle@tiscali.nl>,
	isdn4linux@listserv.isdn4linux.de,
	Al Viro <viro@zeniv.linux.org.uk>,
	Holger Schurig <holgerschurig@googlemail.com>,
	Harald Welte <laforge@gnumonks.org>
Subject: Re: [PATCH v2 5/5] isdn: move capi drivers to staging
Date: Mon, 8 Nov 2021 11:58:23 +0100	[thread overview]
Message-ID: <CAK8P3a0=+w-CR_3uUr3Vi8E7v1z1O40K81pZU6y67u5ns8tCHA@mail.gmail.com> (raw)
In-Reply-To: <20211108094845.cytlyen5nptv4elu@intra2net.com>

On Mon, Nov 8, 2021 at 10:48 AM Thomas Jarosch
<thomas.jarosch@intra2net.com> wrote:
> You wrote on Fri, Apr 26, 2019 at 09:58:49PM +0200:
> > I tried to find any indication of whether the capi drivers are still in
> > use, and have not found anything from a long time ago.
> >
> > With public ISDN networks almost completely shut down over the past 12
> > months, there is very little you can actually do with this hardware. The
> > main remaining use case would be to connect ISDN voice phones to an
> > in-house installation with Asterisk or LCR, but anyone trying this in
> > turn seems to be using either the mISDN driver stack, or out-of-tree
> > drivers from the hardware vendors.
> >
> > I may of course have missed something, so I would suggest moving these
> > three drivers (avm, hysdn, gigaset) into drivers/staging/ just in case
> > someone still uses them.
> >
> > If nobody complains, we can remove them entirely in six months, or
> > otherwise move the core code and any drivers that are still needed back
> > into drivers/isdn.
>
> just a quick follow up on this one: Intra2net is officially
> removing ISDN fax support from our distribution on 2022-06-30.
>
> Since we are still running on kernel 4.19 and plan on upgrading to 5.10 some day
> soonish, there's one less ISDN user to care about in future kernel maintenance.
>
> This makes me even wonder how many linux ISDN users are left these days.

isdn4linux was already removed from the kernel as planned above.

I'm fairly sure the bluetooth capi/cmtp support can just be removed, it
seems to only cause security holes as recently discussed, and is otherwise
fairly useless, but Marcel still wanted to keep it as part of the bluetooth
stack. If this is still the case, we could consider merging all of
drivers/isdn/capi/ into net/bluetooth/cmtp/.

When removal of mISDN came up last, Harald Welte mentioned that some
of the code is still used by Osmocom/OpenBSC[1] to drive the E1 line cards.
I'm not sure if this is still the case, of if they have since migrated
to another
driver.

I see that Karsten's external mISDN modules were last updated for
v5.4 and don't build with newer kernels because of trivial interface changes.

      Arnd

[1] https://osmocom.org/projects/openbsc/wiki/MISDN
[2] https://github.com/ISDN4Linux/mISDN