[systemd-devel] [HEADSUP] libsystemd-bus + kdbus plans

Greg KH gregkh at linuxfoundation.org
Mon Mar 25 06:28:27 PDT 2013

On Mon, Mar 25, 2013 at 01:06:57PM +0000, Simon McVittie wrote:
> On 20/03/13 22:35, Lennart Poettering wrote:
> > kdbus is a new kernel implementation of D-Bus that Kay and Greg have
> > been working on.
> Please talk to the D-Bus maintainers about any reimplementations or
> replacements for D-Bus; we are on dbus at lists.freedesktop.org.
> (Cross-posted.)
> Which parts of the D-Bus Specification does kdbus use?

The "ideas" only, the wire protocol is quite different, and in reality,
unknown as it isn't implemented yet, so all of your questions are a bit
premature, sorry.

> > d) Port gdbus + classic libdbus.so to become clients for kdbus, too.
> How do the other reimplementations of D-Bus (I am aware of at least
> ndesk-dbus (C#), dbus-java, haskell-dbus, and Net::DBus (Perl)) interact
> with kdbus? For instance, is there a bridge to the traditional D-Bus
> wire protocol over Unix/IP/IPv6 stream sockets?

Again, unknown, give us some time to get there.

> As far as I understand it, in the AF_BUS patchsets, the dbus-daemon
> listened on both AF_BUS and stream sockets and bridged messages where
> necessary, allowing interoperability without a flag day
> (AF_BUS-to-AF_BUS messages bypassed the dbus-daemon entirely, while
> AF_BUS-to-stream and stream-to-stream messages continued to pass through
> the dbus-daemon). Obviously, anything requiring the performance gains of
> a kernel-assisted transport still requires porting, but there doesn't
> have to be a flag day.

And odds are, there will not need to be a flag-day here either, if the
library ends up being plug-in compatible for userspace applications.
Which is the goal.

thanks for your patience,

greg k-h

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