RE: Linux 2.6.35/TIPC 2.0 ABI breaking changes

From: Jon Maloy
Date: Wed Oct 20 2010 - 14:37:49 EST


<...>

>
> Just to try to understand better how things works, or are supposed to
> work: do the subscription and event messages (and I mean the
> struct tipc_subscr and tipc_event published in tipc.h) really
> go over the wire or are only used to communicate the stack to
> the application inside a node?

Both. And, given TIPC fundamental "location transparency" principle
the sender (or receiver) at user level does not need to know the
difference.
For a TIPC user, all messages are "local", insofar they stay within
the same cluster.

>
> I think this is a crucial matter, since it defines if the
> changes cross kernel/userspace boundaries only or it also
> crosses the kernel/network boundaries.
>
> > Remember, permitting both is a superset of the current one
> (NBO only)
> > so it is fully backwards compatible. We break absolutly nothing by
> > permitting this.
>
> I think if they really go through the wire, it should be in
> NBO, and if tipc_subscr and tipc_event are used only
> internally, we can still fix the userspace messages when
> sending them through the wire.

There are plenty of protocols around not using NBO over the wire.
This is not a must.

>
> In any case, I agree that the patches should be reverted and
> a solution should be planned with more time and consensus.
>
> Thanks.
>
> --
> Leandro Lucarella (AKA luca) http://llucax.com.ar/
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