Linux 6.3 printk Changes Prepare For Threaded/Atomic Consoles
Linux's current console printing is not compatible with the real-time kernel mode but to address that in the works for several months has been threaded/atomic console support, which then opens the door for the rest of the PREEMPT_RT patches to be fully mainlined.
The printk code for Linux 6.3 only includes a refactoring of the printk code in preparation for introducing atomic consoles that cannot share the global buffers. For Linux 6.3 though that atomic/threaded console support isn't ready. The new printk code makes use of two new lockless functions for reading and formatting of printk messages to the console. The new functions can be used from any context and set the stage for introducing threaded/atomic consoles hopefully in the near term.
The updates for printk in Linux 6.3 are laid out via this kernel pull request.
At the moment the current linux-rt-patches against Linux 6.2 upstream is just over 50 patches needing to be applied for the real-time kernel support.