Re: [PATCH net-next] Remove DECnet support from kernel

Re: [PATCH net-next] Remove DECnet support from kernel

[Nikolay Aleksandrov]

On 18/08/2022 03:43, Stephen Hemminger wrote:
> DECnet is an obsolete network protocol that receives more attention
> from kernel janitors than users. It belongs in computer protocol
> history museum not in Linux kernel.
> 
> It has been "Orphaned" in kernel since 2010. The iproute2 support
> for DECnet was dropped in 5.0 release. The documentation link on
> Sourceforge says it is abandoned there as well.
> 
> Leave the UAPI alone to keep userspace programs compiling.
> This means that there is still an empty neighbour table
> for AF_DECNET.
> 
> The table of /proc/sys/net entries was updated to match
> current directories and reformatted to be alphabetical.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> Acked-by: David Ahern <dsahern@kernel.org>
> ---
> 
> Incorporates feedback from the initial RFC.
> The MPLS neighbour table to family table is left alone.
> 

Acked-by: Nikolay Aleksandrov <razor@blackwall.org>

Re: [PATCH net-next] Remove DECnet support from kernel

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem@davemloft.net>:

On Wed, 17 Aug 2022 17:43:21 -0700 you wrote:
> DECnet is an obsolete network protocol that receives more attention
> from kernel janitors than users. It belongs in computer protocol
> history museum not in Linux kernel.
> 
> It has been "Orphaned" in kernel since 2010. The iproute2 support
> for DECnet was dropped in 5.0 release. The documentation link on
> Sourceforge says it is abandoned there as well.
> 
> [...]

Here is the summary with links:
  - [net-next] Remove DECnet support from kernel
    https://git.kernel.org/netdev/net-next/c/1202cdd66531

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH net-next] Remove DECnet support from kernel

[Jiri Slaby]

On 18. 08. 22, 2:43, Stephen Hemminger wrote:
> DECnet is an obsolete network protocol that receives more attention
> from kernel janitors than users. It belongs in computer protocol
> history museum not in Linux kernel.
> 
> It has been "Orphaned" in kernel since 2010. The iproute2 support
> for DECnet was dropped in 5.0 release. The documentation link on
> Sourceforge says it is abandoned there as well.
> 
> Leave the UAPI alone to keep userspace programs compiling.
> This means that there is still an empty neighbour table
> for AF_DECNET.
> 
> The table of /proc/sys/net entries was updated to match
> current directories and reformatted to be alphabetical.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> Acked-by: David Ahern <dsahern@kernel.org>

...
>   include/uapi/linux/dn.h                       |  149 -
>   include/uapi/linux/netfilter_decnet.h         |   72 -

Hi,

this breaks userspace. Some projects include linux/dn.h:

   https://codesearch.debian.net/search?q=include.*linux%2Fdn.h&literal=0


I found Trinity fails to build:
  net/proto-decnet.c:5:10: fatal error: linux/dn.h: No such file or 
directory
      5 | #include <linux/dn.h>



Should we provide the above as empty files?

thanks,
-- 
js
suse labs

Re: [PATCH net-next] Remove DECnet support from kernel

[Jan Engelhardt]

On Monday 2023-01-09 08:04, Jiri Slaby wrote:
> On 18. 08. 22, 2:43, Stephen Hemminger wrote:
>> DECnet is an obsolete network protocol
>
> this breaks userspace. Some projects include linux/dn.h:
>
>  https://codesearch.debian.net/search?q=include.*linux%2Fdn.h&literal=0
>
> I found Trinity fails to build:
> net/proto-decnet.c:5:10: fatal error: linux/dn.h: No such file or directory
>     5 | #include <linux/dn.h>
>
> Should we provide the above as empty files?

Not a good idea. There may be configure tests / code that merely checks for
dn.h existence without checking for specific contents/defines. If you provide
empty files, this would fail to build:

#include "config.h"
#ifdef HAVE_LINUX_DN_H
#	include <linux/dn.h>
#endif
int main() {
#ifdef HAVE_LINUX_DN_H
	socket(AF_DECNET, 0, DNPROTO_NSP); // or whatever
#else
	...
#endif
}

So, with my distro hat on, outright removing header files feels like the
slightly lesser of two evils. Given the task to port $arbitrary software
between operating systems, absent header files is something more or less
"regularly" encountered, so one could argue we are "trained" to deal with it.
But missing individual defines is a much deeper dive into the APIs and
software to patch it out.

Re: [PATCH net-next] Remove DECnet support from kernel

[Jiri Slaby]

On 09. 01. 23, 9:14, Jan Engelhardt wrote:
> 
> On Monday 2023-01-09 08:04, Jiri Slaby wrote:
>> On 18. 08. 22, 2:43, Stephen Hemminger wrote:
>>> DECnet is an obsolete network protocol
>>
>> this breaks userspace. Some projects include linux/dn.h:
>>
>>   https://codesearch.debian.net/search?q=include.*linux%2Fdn.h&literal=0
>>
>> I found Trinity fails to build:
>> net/proto-decnet.c:5:10: fatal error: linux/dn.h: No such file or directory
>>      5 | #include <linux/dn.h>
>>
>> Should we provide the above as empty files?
> 
> Not a good idea. There may be configure tests / code that merely checks for
> dn.h existence without checking for specific contents/defines. If you provide
> empty files, this would fail to build:
> 
> #include "config.h"
> #ifdef HAVE_LINUX_DN_H
> #	include <linux/dn.h>
> #endif
> int main() {
> #ifdef HAVE_LINUX_DN_H
> 	socket(AF_DECNET, 0, DNPROTO_NSP); // or whatever
> #else
> 	...
> #endif
> }
> 
> So, with my distro hat on, outright removing header files feels like the
> slightly lesser of two evils. Given the task to port $arbitrary software
> between operating systems, absent header files is something more or less
> "regularly" encountered, so one could argue we are "trained" to deal with it.
> But missing individual defines is a much deeper dive into the APIs and
> software to patch it out.

Right, we used to keep providing also defines and structs in uapi 
headers of removed functionality. So that the above socket would 
compile, but fail during runtime.

I am not biased to any solution. In fact, I found out trinity was fixed 
already. So either path networking takes, it's fine by me. I'm not sure 
about the chromium users, though (and I don't care).

thanks,
-- 
js
suse labs

Re: [PATCH net-next] Remove DECnet support from kernel

[Arnd Bergmann]

On Mon, Jan 9, 2023, at 09:34, Jiri Slaby wrote:
> On 09. 01. 23, 9:14, Jan Engelhardt wrote:
>> On Monday 2023-01-09 08:04, Jiri Slaby wrote:
>
> Right, we used to keep providing also defines and structs in uapi 
> headers of removed functionality. So that the above socket would 
> compile, but fail during runtime.
>
> I am not biased to any solution. In fact, I found out trinity was fixed 
> already. So either path networking takes, it's fine by me. I'm not sure 
> about the chromium users, though (and I don't care).

Chromium and some of the others look like automatically generated
lists of files and the rest seem to have compile-time checks.

From a brief look at all the packages in the debian codesearch
link you provided, I don't see any that are likely to cause
problems aside from trinity.

    Arnd