It Doesn't Look Like KDBUS Will Make It For Linux 4.1
While Linux 4.1 is bringing many new features and improvements, there's one addition that's noticeably absent.
To frequent Phoronix readers, the missing feature is, of course, KDBUS. KDBUS developers had been planning to land it in 2014 but that didn't pan out and now most likely they're looking at a H2'2015 arrival for this feature.
KDBUS is aimed to be a new kernel IPC mechanism inspired by D-Bus. KDBUS is being sought after by systemd, PulseAudio, and other possible scenarios for providing better security and performance over D-Bus in user-space.
Greg Kroah-Hartman had sent in the KDBUS pull request for Linux 4.1 but it faced stiff criticism by upstream developers. Some minor legitimate issues were pointed out in the kernel mailing list discussion, while others didn't like that it wasn't reviewed more and did not appreciate its overall design similar to D-Bus for making it easy for user-space application developers to quickly adapt to using. Linus himself also expressed some criticism and potential security issues with the current KDBUS code.
Unless Torvalds changes his mind in the next few hours about pulling KDBUS (there's been no new patches / revisions of the patch series yet to come by Greg KH for this merge window), it will likely be postponed until the Linux 4.2 kernel or longer. At least Linux 4.1 has a lot of other good stuff to get excited over.
Update: Linux 4.1-rc1 was released and indeed KDBUS wasn't accepted.