PREEMPT_RT was a set of out-of-treepatches for theLinux kernel which implement both hard and softreal-time computing capabilities.[1]
On September 20, 2024, PREEMPT_RT was fully merged and enabled inmainline Linux on the supported architecturesx86,x86_64,RISC-V andARM64.[2] This made kernel v6.12 the first release to include baked-in real-time capability.
The PREEMPT_RT patchset has been in development since 2005.[3] In 2021, the preemption core locking code was merged.[4][5]
Since February 2023, Canonical has been releasing real-time versions of Ubuntu Pro, free for personal and small-scale commercial use in up to 5 machines.[6][7] The real-time kernel can be added to various existing Ubuntu releases through an enablement process.[7] These kernels include the PREEMPT_RT patchset and offer long-term support.[7]
MontaVista Software has been releasing a real-time Linux distribution containing the PREEMPT_RT patchset since the early 2000. Montavista's current main embedded Linux product,CGX, contains real-time preemption as a standard feature.
At the September 2024 European Open Source Summit, Linus Torvalds announced that PREEMPT_RT had been accepted into the mainline Linux kernel after a protracted development hurdle involving theprintk kernel logging facility.
