Re: [PATCH 00/12] Add kdbus implementation

On Wed, Oct 29, 2014 at 04:11:06PM -0700, Greg Kroah-Hartman wrote:

On Thu, Oct 30, 2014 at 12:00:16AM +0100, Jiri Kosina wrote:

quoted

On Wed, 29 Oct 2014, Greg Kroah-Hartman wrote:

quoted

kdbus is a kernel-level IPC implementation that aims for resemblance to
the the protocol layer with the existing userspace D-Bus daemon while
enabling some features that couldn't be implemented before in userspace.

I'd be interested in the features that can't be implemented in userspace 
(and therefore would justify existence of kdbus in the kernel). Could you 
please point me to such list / documentation?

Lennart has given whole talks about this in the past, here's a recent
talk going into the details:
	https://www.youtube.com/watch?v=HPbQzm_iz_k

quoted

It seems to me that most of the highlight features from the cover letter 
can be "easily" (for certain definition of that word, of course) 
implemented in userspace (vmsplice(), sending fd through unix socket, user 
namespaces, UUID management, etc).

We have dbus in userspace today, but that requires extra copies of data,
and isn't easy, or even possible, to do some of the application-specific
bus logic that kdbus provides.  See the talk above for details, there
are slides around somewhere with just text that we can add to the cover
letter if that will help out in future spins of this patch series.

Here's an article describing it as well:
	https://lwn.net/Articles/580194/