isdn: remove isdn4linux

With all isdn4linux hardware drivers gone, this is only a wrapper around
CAPI to support old user space. However, from looking at the mailing
list, it seems that the last time anyone asked about it was in 2014,
when the upgrade from a linux-2.4 installation failed, and mISDN was
suggested as a replacement.

The largest public ISDN network (Deutsche Telekom) was supposed to be
shut down 2018, which must have drastically reduced the number of legacy
installations.

When we last discussed removing i4l in 2016, Karsten Keil suggested
revisiting this in 2018. I guess this is overdue.

Link: http://listserv.isdn4linux.de/pipermail/isdn4linux/2014-October/006165.html
Link: https://patchwork.kernel.org/patch/8484861/#17900371
Link: https://listserv.isdn4linux.de/pipermail/isdn4linux/2019-April/thread.html
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 0 insertions, 224 deletions

diff --git a/Documentation/isdn/syncPPP.FAQ b/Documentation/isdn/syncPPP.FAQ
deleted file mode 100644
index 3257a4bc0786..000000000000
--- a/Documentation/isdn/syncPPP.FAQ
+++ /dev/null
@@ -1,224 +0,0 @@
-simple isdn4linux PPP FAQ .. to be continued .. not 'debugged' 
--------------------------------------------------------------------
-
-Q01: what's pppd, ipppd, syncPPP, asyncPPP ??
-Q02: error message "this system lacks PPP support"
-Q03: strange information using 'ifconfig'
-Q04: MPPP?? What's that and how can I use it ...
-Q05: I tried MPPP but it doesn't work 
-Q06: can I use asynchronous PPP encapsulation with network devices
-Q07: A SunISDN machine can't connect to my i4l system
-Q08: I wanna talk to several machines, which need different configs
-Q09: Starting the ipppd, I get only error messages from i4l
-Q10: I wanna use dynamic IP address assignment 
-Q11: I can't connect. How can I check where the problem is.
-Q12: How can I reduce login delay? 
-
--------------------------------------------------------------------
-
-Q01: pppd, ipppd, syncPPP, asyncPPP .. what is that ?
-   what should I use?
-A: The pppd is for asynchronous PPP .. asynchronous means
-   here, the framing is character based. (e.g when
-   using ttyI* or tty* devices)
-
-   The ipppd handles PPP packets coming in HDLC
-   frames (bit based protocol) ... The PPP driver
-   in isdn4linux pushes all IP packets direct
-   to the network layer and all PPP protocol
-   frames to the /dev/ippp* device. 
-   So, the ipppd is a simple external network
-   protocol handler.
-
-   If you login into a remote machine using the
-   /dev/ttyI* devices and then enable PPP on the
-   remote terminal server -> use the 'old' pppd
-
-   If your remote side immediately starts to send
-   frames ... you probably connect to a 
-   syncPPP machine .. use the network device part
-   of isdn4linux with the 'syncppp' encapsulation
-   and make sure, that the ipppd is running and 
-   connected to at least one /dev/ippp*. Check the 
-   isdn4linux manual on how to configure a network device.
-
---
-
-Q02: when I start the ipppd .. I only get the
-   error message "this system lacks PPP support"
-A: check that at least the device 'ippp0' exists.
-   (you can check this e.g with the program 'ifconfig')
-   The ipppd NEEDS this device under THIS name .. 
-   If this device doesn't exists, use:
-	isdnctrl addif ippp0
-	isdnctrl encap ippp0 syncppp
-	... (see isdn4linux doc for more) ...
-A: Maybe you have compiled the ipppd with another
-   kernel source tree than the kernel you currently
-   run ... 
-
---
-
-Q03: when I list the netdevices with ifconfig I see, that
-   my ISDN interface has a HWaddr and IRQ=0 and Base 
-   address = 0 
-A: The device is a fake ethernet device .. ignore IRQ and baseaddr
-   You need the HWaddr only for ethernet encapsulation.
-   
---
-
-Q04: MPPP?? What's that and how can I use it ...
-
-A: MPPP or MP or MPP (Warning: MP is also an 
-   acronym for 'Multi Processor') stands for
-   Multi Point to Point and means bundling
-   of several channels to one logical stream.
-   To enable MPPP negotiation you must call the
-   ipppd with the '+mp' option. 
-   You must also configure a slave device for
-   every additional channel. (see the i4l manual
-   for more)
-   To use channel bundling you must first activate
-   the 'master' or initial call. Now you can add 
-   the slave channels with the command:
-       isdnctrl addlink <device>
-   e.g:
-       isdnctrl addlink ippp0
-   This is different from other encapsulations of
-   isdn4linux! With syncPPP, there is no automatic
-   activation of slave devices.
-
---
-
-Q05: I tried MPPP but it doesn't work .. the ipppd
-   writes in the debug log something like:
-   .. rcvd [0][proto=0x3d] c0 00 00 00 80 fd 01 01 00 0a ...
-   .. sent [0][LCP ProtRej id=0x2 00 3d c0 00 00 00 80 fd 01 ...
-
-A: you forgot to compile MPPP/RFC1717 support into the
-   ISDN Subsystem. Recompile with this option enabled.
-
---
-
-Q06: can I use asynchronous PPP encapsulation
-   over the network interface of isdn4linux ..
-
-A: No .. that's not possible .. Use the standard
-   PPP package over the /dev/ttyI* devices. You
-   must not use the ipppd for this.
-   
---
-
-Q07: A SunISDN machine tries to connect my i4l system,
-   which doesn't work.
-   Checking the debug log I just saw garbage like:
-!![ ... fill in the line ... ]!!
-
-A: The Sun tries to talk asynchronous PPP ... i4l
-   can't understand this ... try to use the ttyI*
-   devices with the standard PPP/pppd package
-
-A: (from Alexanter Strauss: )
-!![ ... fill in mail ]!!
-
---
-
-Q08: I wanna talk to remote machines, which need
-   a different configuration. The only way
-   I found to do this is to kill the ipppd and
-   start a new one with another config to connect
-   to the second machine. 
-
-A: you must bind a network interface explicitly to
-   an ippp device, where you can connect a (for this
-   interface) individually configured ipppd.
-
---
-
-Q09: When I start the ipppd I only get error messages
-   from the i4l driver .. 
-
-A: When starting, the ipppd calls functions which may 
-   trigger a network packet. (e.g gethostbyname()).
-   Without the ipppd (at this moment, it is not
-   fully started) we can't handle this network request.
-   Try to configure hostnames necessary for the ipppd
-   in your local /etc/hosts file or in a way, that
-   your system can resolve it without using an
-   isdn/ippp network-interface.
-
---
-
-Q10: I wanna use dynamic IP address assignment ... How 
-   must I configure the network device.
-
-A: At least you must have a route which forwards
-   a packet to the ippp network-interface to trigger
-   the dial-on-demand.
-   A default route to the ippp-interface will work.
-   Now you must choose a dummy IP address for your
-   interface.
-   If for some reason you can't set the default
-   route to the ippp interface, you may take any 
-   address of the subnet from which you expect your
-   dynamic IP number and set a 'network route' for
-   this subnet to the ippp interface.
-   To allow overriding of the dummy address you
-   must call the ipppd with the 'ipcp-accept-local' option.
-
-A: You must know, how the ipppd gets the addresses it wanna
-   configure. If you don't give any option, the ipppd
-   tries to negotiate the local host address!
-   With the option 'noipdefault' it requests an address
-   from the remote machine. With 'useifip' it gets the
-   addresses from the net interface. Or you set the address
-   on the option line with the <a.b.c.d:e.f.g.h> option.
-   Note: the IP address of the remote machine must be configured
-   locally or the remote machine must send it in an IPCP request.
-   If your side doesn't know the IP address after negotiation, it
-   closes the connection!
-   You must allow overriding of address with the 'ipcp-accept-*'
-   options, if you have set your own or the remote address 
-   explicitly.
-
-A: Maybe you try these options .. e.g:   
-
-    /sbin/ipppd :$REMOTE noipdefault /dev/ippp0
-
-   where REMOTE must be the address of the remote machine (the
-   machine, which gives you your address)
-
---
-
-Q11: I can't connect. How can I check where the problem is.
-
-A: A good help log is the debug output from the ipppd...
-   Check whether you can find there:
-   - only a few LCP-conf-req SENT messages (less then 10)
-     and then a Term-REQ:
-     -> check whether your ISDN card is well configured
-        it seems, that your machine doesn't dial
-        (IRQ,IO,Proto, etc problems)
-        Configure your ISDN card to print debug messages and
-        check the /dev/isdnctrl output next time. There
-        you can see, whether there is activity on the card/line.
-   - there are at least a few RECV messages in the log:
-     -> fine: your card is dialing and your remote machine
-        tries to talk with you. Maybe only a missing 
-        authentication. Check your ipppd configuration again.
-   - the ipppd exits for some reason:
-     -> not good ... check /var/adm/syslog and /var/adm/daemon.
-        Could be a bug in the ipppd.
-
---
-
-Q12: How can I reduce login delay?
-
-A: Log a login session ('debug' log) and check which options 
-  your remote side rejects. Next time configure your ipppd
-  to not negotiate these options. Another 'side effect' is, that
-  this increases redundancy. (e.g your remote side is buggy and
-  rejects options in a wrong way).
-
-
-