While there has been mainline Linux kernel support for real-time (RT) on x86/x86_64, ARM64 (AArch64), and RISC-V since Linux 6.12 and LoongArch RT since Linux 6.13 , only now is the ARM (non-ARM64/AArch64) support for older SoCs seeing mainline real-time support with Linux 7.1.
The ARM support for real-time had continued to be carried by the few remaining out-of-tree RT patches but for Linux 7.1 the final hurdles have been overcome to get all the necessary bits in mainline. Prior to the Linux 7.1-rc1 release this past weekend,
this Git merge happened that cleaned up the ARM fault handling and in turn allowing PREEMPT_RT to work for mainline ARM Linux builds.
Indeed with today's v7.1-rc1-rt1 patch release , it notes all the ARM patches are gonee with "everything required" having made it into Linux 7.1-rc1.
As for what the out-of-tree RT patch queue is looking like these days, the bulk are some fixes to the Intel i915 DRM driver, adding a /sys/kernel/realtime entry to indicate it's a real-time kernel, and the remaining patches yet to be mainlined for enabling real-time support on PowerPC. The current patch queue as of Linux 7.1 Git can be found via this Git branch .