This non-BKL (NBCON) consoles support is part of the broader effort around threaded/atomic consoles support but to ease the effort in getting the code reviewed and upstreamed, the patch series sent out this week was just around making the console support non-blocking. This is to avoid the current console/printk subsystem relying on the Big Kernel Lock (BKL).
Those interested in this latest work on non-blocking console support for Linux can see this patch series in its latest form. Hopefully that work will manage to land soon and in turn be able to get the rest of the real-time work upstreamed into the mainline Linux kernel.