The Linux real-time patch series has been getting smaller with time and quite close to crossing the finish line with just around 50 patches to be merged. This allows for building a real-time / fully preemptible kernel off the mainline code for embedded Linux systems.
For years there had been talk of PREEMPT_RT coming "soon" to mainline but ultimately didn't pan out. The Linux RT developers were held up by funding .
The change this year though was Intel acquiring Linutronix as the Linux consulting firm heavily involved in the PREEMPT_RT patches.
Now today the word is that PREEMPT_RT could be ready for Linux 5.20 if the last two blockers are sorted out this week. Sebastian Andrzej Siewior of Linutronix wrote on the kernel mailing list:
a polite ping for the series. This is one of two road blocks to get RT enabled in v5.20. I don't want to add any pressure just point out that I can't sit still for days since the end is near ;)
Sebastian
That patch series are two signal/ptrace related patches needed for the PREEMPT_RT series. We'll see over the next two weeks during the Linux 5.20 merge window if the PREEMPT_RT patches are all aligned to finally be merged and there are no last minute issues or objections from Linus Torvalds or other key participants.