Re: [PATCH 00/12] Add kdbus implementation

On Thu, Oct 30, 2014 at 12:26:33AM +0100, Jiri Kosina wrote:

On Thu, 30 Oct 2014, Jiri Kosina wrote:

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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,

But we can do zero-copy between processess for quite some time already, so 
what exactly is the issue here?

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and isn't easy, or even possible, to do some of the application-specific
bus logic that kdbus provides.  

I unfortunately have absolutely no idea what should I imagine here.

Also, I think I have heard that binder is going out of staging now, right?

Yes, but that needs documentation, which I'm working on at the moment :)

I admittedly have very limited understanding of both binder and kdbus, but 
I guess that is the case for many folks. My understanding is that they are 
providing very similar functionality, so explanation why we need *both* in 
the kernel would be very interesting as well.

They do very different things, see this writeup I did a while ago about
the differences between them:
	http://kroah.com/log/blog/2014/01/15/kdbus-details/

thanks,

greg k-h