Re: [GIT PULL] kdbus for 4.1-rc1

Greg Kroah-Hartman
2015-04-21T12:56:38Z

On Tue, Apr 21, 2015 at 01:03:59PM +0200, Jiri Kosina wrote:
> On Tue, 21 Apr 2015, Greg Kroah-Hartman wrote:
>
> > > We do need something for the multicast messaging. Whether that's
> > > supporting AF_LOCAL, SOCK_RDP with multicast or something else (POSIX
> > > message queue extensions ?). There's no real IP layer reliable ordered
> > > multicast delivery system that is low latency and lightweight because
> > > once it hits real networks it changes from a hard problem into a
> > > seriously hard problem because of multicast implosions and the like.
> >
> > This was attempted in the past with AF_DBUS, but the networking
> > maintainers rightfully pointed out that the model there did not work.
>
> BTW, I don't think this has been brought up in this discussion yet ...
> please correct me if I am wrong, my memory is very faint here (*), but
> wasn't the main objection to AF_BUS that defining what happens when one of
> the subscribed receivers disconnects is a policy matter, and as such
> belongs to userspace (which wasn't the case with the submitted AF_BUS
> implementation)?
>
> Was that considered unfixable and AF_BUS consequently given up because of
> this?

I think it was one of the reasons, I seem to remember many more. At
that time, I had lunch with David Miller and he told me a few specific
reasons along those lines, and that it just wasn't going to work as a
network protocol at all, and to not try that method anymore, but
instead, do it as a specific IPC interface, as has been done here :)

thanks,

greg k-h