The Linux kernel developers have announced the submission of final changes necessary for building the kernel with the PREEMPT_RT option, which includes tools for real-time operation, to the linux-next branch that will be used for the 6.12 release. After the changes are accepted into the main kernel branch, the PREEMPT_RT mode will be available for the X86, ARM64, and RISC-V architectures. Support for the ARM and POWERPC architectures will be added later, for which not all patches have yet been sent to the kernel.
The development of real-time mode implementation for the Linux kernel has been underway since 2005 as part of the 'Realtime-Preempt' ('-rt') project and has been supported by the Linux Foundation since 2015. Until now, the implementation of the PREEMPT_RT mode was delivered in the form of external patches, based on which some distributions, such as RHEL, SUSE, and Ubuntu, created separate Realtime editions of their products, sought after in areas such as financial systems, audio and video processing devices, aviation, medicine, robotics, telecommunications, and industrial systems, where predictable event processing time is essential.
In 2019, efforts were initiated to promote the PREEMPT_RT patches into the main kernel. The configuration file for kernel 5.3 included the PREEMPT_RT option to enable real-time mode, but the integration of the necessary changes for its operation has stretched over 5 years. Now this path is nearing completion, and most likely, in the 6.12 release, the kernel will be able to be built in PREEMPT_RT mode without the need for additional patches.
The last missing capability in the kernel that prevented the activation of the PREEMPT_RT mode was the support for non-blocking atomic output via the printk function. This capability has now been accepted into the linux-next branch. The implementation of an atomic and non-blocking console for the UART 8250 driver is also awaiting inclusion in the linux-next branch, without which the output of emergency messages to the console from code in an atomic context has been disabled for now.
Source: opennet.ru
