Linux Very Close To Enabling Real-Time "PREEMPT_RT" Support
Years in the making, the loop is almost finally closed on having PREEMPT_RT in the mainline Linux kernel. The last remaining blocker has been around the non-blocking console / atomic console support and that work is trickling into linux-next for possible merging into Linux 6.12.
Sebastian Andrzej Siewior of Linutronix posted a new patch series to the Linux kernel mailing list minutes ago. Sebastian wrote in the patch series Allow to enable PREEMPT_RT:
The printk bits required for PREEMPT_RT are sitting in linux-next. This was the last known roadblock for PREEMPT_RT. The RT queue has additionally the "atomic console" for the 8250 UART which is not yet in linux-next. This means "legacy console" behaviour as in no printing from atomic context in emergency cases. The 8250 UART driver is the only one providing "atomic console" support as of today.
With the printk bits merged, PREEMPT_RT could be enabled on X86, ARM64 and Risc-V. These three architectures merged required changes over the years leaving me in a position where I have no essential changes in the queue that would affect them. ARM and POWERPC have a few essential patches left and I lost track of MIPS.
We'll see if PREEMPT_RT manages to get over the finish line for the upcoming Linux 6.12 cycle otherwise it's looking good that things could be buttoned up with the Linux 6.13 kernel release as the first stable series of 2025. Linux 6.12 meanwhile is slated to be this year's LTS kernel version.
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