The real time developer team is currently working on the following topics that change current kernel functionality:

• CPU hotplug overhaul: Change of the CPU hotplug notifier infrastructure into a state machine (for detailed description see LKML: cpu/hotplug: Core infrastructure for cpu hotplug rework). Afterwards all CPU hotplug notifier users have to be converted to the CPU hotplug state machine.
• Timer infrastructure: Timer wheel rebuild is required, because in the current PREEMPT_RT patch (v4.6.2-rt5) and the PREEMPT_RT patches before NOHZ can not be used. The basis for the new timer wheel was posted to LKML (see LKML: timer: Refactor the timer wheel) is now available in 4.8 - NOHZ can now work again with RT.

In addition to the actual development work, the following topics have to be considered:

• Testing
• Documentation
• Longtime Stable Support of the PREEMPT_RT patch

An overview of all the topics that have to be completed for mainlining PREEMPT_RT is given here.