netdev - Re: Kill I4L?

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Date:	Mon, 9 Feb 2015 11:07:55 +0100
From:	Bas Peters <baspeters93@...il.com>
To:	Karsten Keil <kkeil@...ux-pingi.de>
Cc:	Tilman Schmidt <tilman@...p.cc>, Paul Bolle <pebolle@...cali.nl>,
	Joe Perches <joe@...ches.com>,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	"isdn@...ux-pingi.de" <isdn@...ux-pingi.de>,
	Julia Lawall <julia.lawall@...6.fr>,
	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: Kill I4L?

2015-02-09 0:59 GMT+01:00 Karsten Keil <kkeil@...ux-pingi.de>:
> Am 08.02.2015 um 20:47 schrieb Tilman Schmidt:
>> Am 07.02.2015 um 21:43 schrieb Paul Bolle:
>>> On Sat, 2015-02-07 at 11:19 -0800, Joe Perches wrote:
>>>> Does anyone still use these cards?
>>
>>> 0) Good question.
>>
>> I very much doubt it. It was an ISA card, not even PnP. I'd imagine
>> any systems of that kind would be retired by now.
>>
>
> Agreed in general, but I know people still running such ISA based
> machines - mostly PC in industrial environments with ISDN uplinks for
> service and maintenance.
> And I4L is also used in some vending machines for card authorization so
> far I know.
> They usually using old kernels (<3.0) so they are not directly affected
> if this will be removed.
>
>>> 2) Broader picture: if I remember correctly there are now four
>>> different flavors of ISDN in the kernel: - really old: pre-i4l
>>
>> I don't think any traces of that are still present in current kernel
>> releases. It should all have been left behind on the switch to 2.6.
>>
>
> Yes.
>
>>> - very old: i4l - just old: CAPI - not so old: mISDN
>>
>> Those are the in-tree ones. To make matters worse, the Asterisk people
>> invented three more (Zaptel, DAHDI and vISDN) which are maintained
>> out-of-tree. Apparently they weren't satisfied with any the in-tree
>> ones and didn't feel like helping to improve one of them to match
>> their needs.
>>
>>> [snip] So the current ISDN situation is a bit messy.
>>
>> That's putting it mildly.
>>
>>> Tilman might be able to provide a clearer, and maybe less grumpy,
>>> summary of the current situation.
>>
>> Don't know about either. ;-)
>>
>>> [M]aybe we should consider, say, removing i4l and pre i4l and see
>>> who complains. That might be a rude thing to do. So perhaps the
>>> various ISDN flavors should be left alone until ... what exactly?
>>
>> I'd support that step. I don't think it'll hurt anyone because the
>> cards supported by i4l are mostly ISA cards anyway. The only exceptions
>> are the HiSax family which is now supported by mISDN, and the Hypercope
>> family which is supported by CAPI.
>>
>> In the past we had Documentation/feature-removal-schedule.txt for
>> announcing removals like that but Linus shot that down on 2012-10-01
>> (commit 9c0ece069b32e8e122aea71aa47181c10eb85ba7) so I guess
>> somebody could just submit a patch series starting with
>>
>> --- a/drivers/isdn/Kconfig
>> +++ b/drivers/isdn/Kconfig
>> @@ -20,25 +20,6 @@ menuconfig ISDN
>>
>>  if ISDN
>>
>> -menuconfig ISDN_I4L
>> -       tristate "Old ISDN4Linux (deprecated)"
>> -       depends on TTY
>> -       ---help---
>> -         This driver allows you to use an ISDN adapter for networking
>> -         connections and as dialin/out device.  The isdn-tty's have a
>> built
>> -         in AT-compatible modem emulator.  Network devices support
>> autodial,
>> -         channel-bundling, callback and caller-authentication without
>> having
>> -         a daemon running.  A reduced T.70 protocol is supported with
>> tty's
>> -         suitable for German BTX.  On D-Channel, the protocols EDSS1
>> -         (Euro-ISDN) and 1TR6 (German style) are supported.  See
>> -         <file:Documentation/isdn/README> for more information.
>> -
>> -         ISDN support in the linux kernel is moving towards a new API,
>> -         called CAPI (Common ISDN Application Programming Interface).
>> -         Therefore the old ISDN4Linux layer will eventually become
>> obsolete.
>> -         It is still available, though, for use with adapters that
>> are not
>> -         supported by the new CAPI subsystem yet.
>> -
>>  source "drivers/isdn/i4l/Kconfig"
>>
>>  menuconfig ISDN_CAPI
>>
>> and working its way from that to remove anything that's become
>> unreachable.
>>
>> Shall I?
>>
>
> But I4L is still the default in some Distros, so we should allow a
> warning period. But again, I'm fine with this to do it.

Is there any explicit reason why 'dead' drivers that might still have
some users ought to be removed?
Does it hurt anyone to leave the code in there, despite it barely
being used? We're not talking about
a particularly huge driver here, either.

>
> Karsten
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