PREEMPT_RT 概述

preempt_rt补丁的技术细节，可以在linuxfoundation的网站Technical details of the real-time preemption上了解到。根据网站上的介绍，大致分为下面这些：

• High resolution timers
• Threaded interrupt handler
• RCU
• rt_mutex
• Sleeping spinlocks
• local_lock

主线 Linux 内核在 v6.12 版本完成了 PREEMPT_RT 核心代码的主线合并，实现原生实时能力。后续迭代中，preempt-rt 相关补丁以增量优化为主，内容大多聚焦驱动层适配与性能微调，整体实时核心框架已稳定固化。从下面的patch-6.18.13-rt4.patch修改内容也能够直观看出

        modified:   arch/arm/Kconfig
        modified:   arch/arm/mm/fault.c
        modified:   arch/powerpc/Kconfig
        modified:   arch/powerpc/include/asm/stackprotector.h
        modified:   arch/powerpc/kvm/Kconfig
        modified:   arch/powerpc/platforms/pseries/Kconfig
        modified:   arch/powerpc/platforms/pseries/iommu.c
        modified:   drivers/gpu/drm/i915/Kconfig
        modified:   drivers/gpu/drm/i915/display/intel_crtc.c
        modified:   drivers/gpu/drm/i915/display/intel_cursor.c
        modified:   drivers/gpu/drm/i915/display/intel_display_trace.h
        modified:   drivers/gpu/drm/i915/display/intel_vblank.c
        modified:   drivers/gpu/drm/i915/gt/intel_engine_cs.c
        modified:   drivers/gpu/drm/i915/gt/intel_execlists_submission.c
        modified:   drivers/gpu/drm/i915/gt/uc/intel_guc.h
        modified:   drivers/gpu/drm/i915/i915_request.c
        modified:   drivers/gpu/drm/i915/i915_trace.h
        modified:   drivers/gpu/drm/i915/intel_uncore_trace.h
        modified:   drivers/tty/serial/8250/8250_core.c
        modified:   drivers/tty/serial/8250/8250_port.c
        modified:   include/linux/serial_8250.h
        modified:   kernel/ksysfs.c
        new file:   localversion-rt

但是为了更方便的阅读preempt_rt的代码实现，之后出现的代码都来自linux-6.8.2

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