[$] The real realtime preemption end game

The addition of realtime support to Linux is a long story; it first
shows up in LWN in 2004. For much of that
time, it has seemed like only a little more work was needed to get across
the finish line; thus we ran headlines like the
realtime preemption endgame — in 2009. At the 2023 Linux Plumbers Conference, Thomas
Gleixner informed the group that, now, the end truly is near. There is
really only one big problem left to be solved before all of that work can
land in the mainline.