KDBUS Merging Prospects Get Debated

The KDBUS in-fighting between upstream Linux kernel developers was once again reignited today after a kernel developer publicly asked Linus Torvalds on the prospects of merging KDBUS.

Kernel developer Andy Lutomirski started a new Linux kernel mailing list thread today entitled kdbus: to merge or not to merge?. Andy asked Linus, "Can you opine as to whether you think that kdbus should be merged? I don't mean whether you'd accept a pull request that Greg may or may not send during this merge window -- I mean whether you think that kdbus should be merged if it had appropriate review and people were okay with the implementation."

The lengthy email also mentioned how systemd is now building KDBUS support by default, KDBUS is not necessary and a giant API surface, the KDBUS sandbox model won't work out in his mind, and other potential issues. Andy concluded, "I think that a very high quality implementation of the kdbus concept and API would be a bit faster than a very high quality userspace implementation of dbus. Other than that, I think it would actually be worse. The kdbus proponents seem to be comparing the current kdbus implementation to the current userspace implementation, and a favorable comparison there is not a good reason to merge it."

Veteran kernel developer Greg Kroah-Hartman who has been doing a lot of the KDBUS development and had sent in the pull request for Linux 4.1 responded, "Ah, a preemptive pull request denial, how nice. I don't think I've ever seen such a thing before, congratulations for creating something so must have previously been lacking in our development model in how to work together in a community in a productive manner. Not."

Other kernel developers have since joined the discussion in wondering the prospects whether they should spend the time or not reviewing the KDBUS code. As of writing this article, Linus Torvalds has yet to comment on this thread. Greg KH also hasn't yet said whether he will submit a KDBUS pull request for Linux 4.2. While KDBUS didn't make it for Linux 4.1, it has seen some improvements and now with systemd 221 the developers are trying to get distribution vendors to start incorporating the support themselves. SD-BUS is also now stable with systemd 221 for targeting KDBUS and D-Bus back-ends for making it easy on Linux application developers interested in high-performance IPC.