Re: [Linux-decnet-user] Proposed removal of DECnet support (was:Re: [BUG] 3.2-rc2:BUG kmalloc-8: Redzone overwritten)

Re: [Linux-decnet-user] Proposed removal of DECnet support (was:Re: [BUG] 3.2-rc2:BUG kmalloc-8: Redzone overwritten)

[Steven Whitehouse]

Hi,

On Wed, 2011-11-30 at 13:52 +0000, mike.gair@tatasteel.com wrote:
> We're using decnet on linux,
> as a way of expanding a control system,
> using DEC PDP11s (actually charon11 emulations).
> 
> So woud be very interested in keeping decnet supported.
> 
> In theory i'd be interested in maintaining it,
> but i'm not sure what amount of work is involved,
> have no experience of kernel, or where to start.
> 
> Any ideas?
> 
> 
So the issue is basically that due to there being nobody currently
maintaining the DECnet stack, it puts a burden on the core network
maintainers when they make cross-protocol changes, as they have to
figure out what impact the changes are likely to have on the DECnet
stack. So its an extra barrier to making cross-protocol code changes.

If there was an active maintainer who could be a source of knowledge
(and the odd patch to help out making those changes) then this issue
would largely go away.

The most important duty of the maintainer is just to watch whats going
on in the core networking development and to contribute the DECnet part
of that. So it would be most likely be more a reviewing of patches and
providing advice role, than one of writing patches (though it could be
that too) and ensuring that the code continues to function correctly by
testing it from time to time.

The ideal maintainer would have an in-depth knowledge of the core Linux
networking stack (socket layer, dst and neigh code), the DECnet specs
and have a good knowledge of C. 

Bearing in mind the low patch volume (almost zero, except for core
stuff), it would probably be one of the subsystems with the least amount
of work to do in maintaining it. So in some ways, a good intro for a new
maintainer.

I do try and keep an eye on what get submitted to the DECnet code and
I'll continue to do that while it is still in the kernel. However, it is
now quite a long time since I last did any substantial work in the
networking area and things have moved on a fair bit in the mean time. I
don't have a lot of time to review DECnet patches these days and no way
to actually test any contributions against a real DECnet implementation.

So I'll provide what help I can to anybody who wants to take the role
on, within those limitations. I'm also happy to answer questions about
why things were done in a particular way, for example.

It is good to know that people are still using the Linux DECnet code
too. It has lived far beyond the time when I'd envisioned it still being
useful :-)

Steve.

> 
> 
> 
> Philipp Schafft <lion@lion.leolix.org> wrote on 29/11/2011 14:47:19:
> 
> > reflum,
> > 
> > On Tue, 2011-11-29 at 15:34 +0100, Steven Whitehouse wrote:
> > 
> > > Has anybody actually tested it
> > > > >> lately against "real" DEC implementations?
> > > > > I doubt it :-)
> > > > DECnet is in use against real DEC implementations - I have
> checked it 
> > > > quite recently against a VAX running OpenVMS. How many people
> are 
> > > > actually using it for real work is a different question though.
> > > > 
> > > Ok, thats useful info.
> > 
> > I confirmed parts of it with tcpdump and the specs some weeks ago.
> The
> > parts I worked on passed :) I also considered to send the tcpdump
> > upstream a patch for protocol decoding.
> > 
> > 
> > > > It's also true that it's not really supported by anyone as I
> orphaned it 
> > > > some time ago and nobody else seems to care enough to take it
> over. So 
> > > > if it's becoming a burden on people doing real kernel work then
> I don't 
> > > > think many tears will be wept for its removal.
> > > > Chrissie
> > > 
> > > Really the only issue with keeping it around is the maintenance
> burden I
> > > think. It doesn't look like anybody wants to take it on, but maybe
> we
> > > should give it another few days for someone to speak up, just in
> case
> > > they are on holiday or something at the moment.
> > > 
> > > Also, I've updated the subject of the thread, to make it more
> obvious
> > > what is being discussed, as well as bcc'ing it again to the DECnet
> list,
> > 
> > I'm very interested in the module. However my problem is that I had
> > nothing to do with kernel coding yet. However I'm currently
> searching a
> > new maintainer for it (I got info about this thread by today).
> > If somebody is interested in this and only needs some "motivation"
> or
> > maybe someone would like to get me into kernel coding, please just
> > reply :)
> > 
> > -- 
> > Philipp.
> > (Rah of PH2)
> > [attachment "signature.asc" deleted by Mike Gair/UK/Corus] 
> >
> ------------------------------------------------------------------------------
> > All the data continuously generated in your IT infrastructure 
> > contains a definitive record of customers, application performance, 
> > security threats, fraudulent activity, and more. Splunk takes this 
> > data and makes sense of it. IT sense. And common sense.
> > http://p.sf.net/sfu/splunk-novd2d
> > _______________________________________________
> > Project Home Page: http://linux-decnet.wiki.sourceforge.net/
> > 
> > Linux-decnet-user mailing list
> > Linux-decnet-user@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-decnet-user
> > 
> 
> 
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Re: [Linux-decnet-user] Proposed removal of DECnet support (was:Re: [BUG] 3.2-rc2:BUG kmalloc-8: Redzone overwritten)

[Philipp Schafft]

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reflum,

On Wed, 2011-11-30 at 14:52 +0000, Steven Whitehouse wrote:
> On Wed, 2011-11-30 at 13:52 +0000, mike.gair@tatasteel.com wrote:
> > In theory i'd be interested in maintaining it,
> > but i'm not sure what amount of work is involved,
> > have no experience of kernel, or where to start.
> > 
> > Any ideas?
> > 
> > 
> So the issue is basically that due to there being nobody currently
> maintaining the DECnet stack, it puts a burden on the core network
> maintainers when they make cross-protocol changes, as they have to
> figure out what impact the changes are likely to have on the DECnet
> stack. So its an extra barrier to making cross-protocol code changes.
> 
> If there was an active maintainer who could be a source of knowledge
> (and the odd patch to help out making those changes) then this issue
> would largely go away.

*nods*


> The most important duty of the maintainer is just to watch whats going
> on in the core networking development and to contribute the DECnet part
> of that. So it would be most likely be more a reviewing of patches and
> providing advice role, than one of writing patches (though it could be
> that too) and ensuring that the code continues to function correctly by
> testing it from time to time.
> 
> The ideal maintainer would have an in-depth knowledge of the core Linux
> networking stack (socket layer, dst and neigh code), the DECnet specs
> and have a good knowledge of C. 

I guess I would fit mostly but I have no idea of the kernel internal
stuff. Also I'm a bit short on time.


> Bearing in mind the low patch volume (almost zero, except for core
> stuff), it would probably be one of the subsystems with the least amount
> of work to do in maintaining it. So in some ways, a good intro for a new
> maintainer.

Jup. This is very true. I hope we will find a new maintainer because of
exactly this point. Maybe somebody like Mike Gair.


> I do try and keep an eye on what get submitted to the DECnet code and
> I'll continue to do that while it is still in the kernel. However, it is
> now quite a long time since I last did any substantial work in the
> networking area and things have moved on a fair bit in the mean time. I
> don't have a lot of time to review DECnet patches these days and no way
> to actually test any contributions against a real DECnet implementation.

I'm glad you are still interested. I'm always happy when I see mails
from you at the DECnet for Linux list.


> So I'll provide what help I can to anybody who wants to take the role
> on, within those limitations. I'm also happy to answer questions about
> why things were done in a particular way, for example.
> 
> It is good to know that people are still using the Linux DECnet code
> too. It has lived far beyond the time when I'd envisioned it still being
> useful :-)

There are still some people interested in it. Btw. on Debian popcon
counts 5356 users.

-- 
Philipp.
 (Rah of PH2)

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Re: [Linux-decnet-user] Proposed removal of DECnet support (was:Re: [BUG] 3.2-rc2:BUG kmalloc-8: Redzone overwritten)

[Ben Hutchings]

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On Sun, 2011-12-04 at 20:50 +0100, Philipp Schafft wrote:
> reflum,
> 
> On Wed, 2011-11-30 at 14:52 +0000, Steven Whitehouse wrote:
[...]
> > It is good to know that people are still using the Linux DECnet code
> > too. It has lived far beyond the time when I'd envisioned it still being
> > useful :-)
> 
> There are still some people interested in it. Btw. on Debian popcon
> counts 5356 users.

This is grossly misleading.  Here's the historical graph showing <100
installations of libdnet until early 2011:
http://qa.debian.org/popcon-graph.php?packages=libdnet

The increase in 2011 is not a sudden resurgence of interest; it comes
from roaraudio[1] users.  For some reason (a joke?) roaraudio has DECnet
support and its packages depend on libdnet.  You can see that the above
graph is precisely correlated with this:
http://qa.debian.org/popcon-graph.php?packages=libroar1

(And so far as I can work out, libroar1 is mostly being installed as a
dependency of an unofficial package of Xine.)

The only reason I know this is because there was a sudden spate of bug
reports on the kernel due to people getting dnet-common installed as a
recommendation of libdnet and then having their Ethernet MAC addresses
reconfigured for DECnet.

[1] Yet another audio mixing daemon

Ben.

-- 
Ben Hutchings
Absolutum obsoletum. (If it works, it's out of date.) - Stafford Beer

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Re: [Linux-decnet-user] Proposed removal of DECnet support (was:Re: [BUG] 3.2-rc2:BUG kmalloc-8: Redzone overwritten)

[Philipp Schafft]

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reflum,

On Mon, 2011-12-05 at 01:23 +0000, Ben Hutchings wrote:
> On Sun, 2011-12-04 at 20:50 +0100, Philipp Schafft wrote:
> > On Wed, 2011-11-30 at 14:52 +0000, Steven Whitehouse wrote:
> [...]
> > > It is good to know that people are still using the Linux DECnet code
> > > too. It has lived far beyond the time when I'd envisioned it still being
> > > useful :-)
> > 
> > There are still some people interested in it. Btw. on Debian popcon
> > counts 5356 users.
> 
> This is grossly misleading.  Here's the historical graph showing <100
> installations of libdnet until early 2011:
> http://qa.debian.org/popcon-graph.php?packages=libdnet

Maybe my statement was missleading. popcon shows 5356 installs. This
includes real users and non-real users. Both groups *may* be affected by
droping the kernel module (in diffrent ways).


> For some reason (a joke?) roaraudio has DECnet
> support and its packages depend on libdnet.

Maybe just because it is usefull for the RoarAudio project.

Anyway, don't take the number too important. It was just a minor note.

-- 
Philipp.
 (Rah of PH2)

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Re: [Linux-decnet-user] Proposed removal of DECnet support (was:Re: [BUG] 3.2-rc2:BUG kmalloc-8: Redzone overwritten)

[Philipp Schafft]

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reflum,

On Fri, 2011-12-02 at 09:14 +0000, mike.gair@tatasteel.com wrote:
> I suspect I'm not up to the job,
> 
> - definitely not got an in-depth knowledge of the core Linux
> networking stack
> or the DECnet specs,
> Have limited, but growing experience of C, (mainly work in coral66)

I'm willing to offer you help with C and the protocol stuff. I'm the
current most active developer of the userland part.


> But I'll have a look at code/documentation
> & see if I understand any of it. 

Ok. If you are still interested let me know if I can help you with the
above. Maybe Steven can give you some pointers for the kernel stuff.

> 
-- 
Philipp.
 (Rah of PH2)

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