Hi Glenn,

On 10/29/2013 02:38 AM, Glenn Schmottlach wrote:
I've been investigating the ConnMan "Session" API and implementation.
It would appear that it relies heavily on a couple of key netfilter
features that are only available in newer Linux Kernels (e.g. Kernel
3.3+).

The Session API comes with a set of features. The main goal is to
support the per application routing and statistics use case.
With the D-Bus API we also support other per application
use case such as notify applications when there a bearer
in the AllowedBearers is online.

We implemented the D-Bus parts first and now we added the
missing pieces for the per application routing and statistics
use cases. That is why you see new dependencies.

In particular per-session accounting is maintained using
netfilter's nfacct feature. Unfortunately, I'm on an i.MX6 platform
and the latest "stable" Linux kernel offered by Freescale is Linux
3.0.35 where the nfacct feature is not available.

Ooch, that is even not the last stable kernel of the 3.0 series.

The question I have
is how forgiving is ConnMan for running on these earlier kernels and
whether I can expect to use any of the ConnMan session features with
this kernel.

Yes, we tried to make sure that the new dependencies are not
hard dependencies.

Perhaps the better question is whether these missing
features will make using ConnMan unstable/unsuitable for this
platform.

No it should not impact the stability etc. If it does it is
a bug which needs to be fixed.

Early experimentation seems to indicate the core features do
in fact work.

Nice, that was we tried to achieved.

I hope the unsuitability is only related to session
support and that I can expect to utilize the other features of the
service without problem. Is this indeed the situation?

If you don't use the Session API at all you should have any
problem.

On a side note, I'm curious to know whether the core ConnMan
developers are sensitive to the fact that the newer kernel features
are not routinely available for all SoCs and BSPs that are commonly
available from the silicon vendors? Is there a minimum kernel version
that is expected in order to use ConnMan?

Yep, we are aware of this fact. We have listed all known
dependencies in the README instead of asking for min version
of kernel. I really hope that the silicon vendors start to
catch up with mainline really soon. The current situation
is bad for everyone for obvious reasons.

Thanks for any insights that can be offered . . .

If you have bug reports etc please do not hesitate to report.

cheers,
daniel
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