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fix(aarch64): remove redundant pending clear in GIC ack - #11860

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fix(aarch64): remove redundant pending clear in GIC ack#11860
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Xenithya:fix/aarch64-gic-ack

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@Xenithya

@Xenithya Xenithya commented Oct 9, 2026

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拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

arm_gic_ack() currently clears the interrupt pending state through GIC_DIST_PENDING_CLEAR before writing the interrupt ID to GIC_CPU_EOI.

This change removes the explicit pending-clear operation and its now-unused mask variable, leaving the CPU interface EOI write as the interrupt acknowledgment operation.

你的解决方案是什么 (what is your solution)

Remove the GIC_DIST_PENDING_CLEAR write and the unused mask variable from arm_gic_ack().

请提供验证的bsp和config (provide the config and bsp)

  • BSP:
  • .config:
  • action:

]

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

  • 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
  • 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

  • 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
  • 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
  • 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
  • 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
  • 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
  • 代码是高质量的 Code in this PR is of high quality
  • 已经使用clang-format 源码格式化工具确保格式符合RT-Thread代码规范 This PR has been formatted with clang-format and complies with RT-Thread code specification
  • 如果是新增bsp, 已经添加ci检查到.github/ALL_BSP_COMPILE.json 详细请参考链接BSP自查

@github-actions

github-actions Bot commented Oct 9, 2026

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👋 感谢您对 RT-Thread 的贡献！Thank you for your contribution to RT-Thread!

为确保代码符合 RT-Thread 的编码规范，请在你的仓库中执行以下步骤运行代码格式化工作流（如果格式化CI运行失败）。
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如有问题欢迎联系我们，再次感谢您的贡献！💐
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@github-actions github-actions Bot added Arch: ARM/AArch64 BSP related with arm libcpu labels Oct 9, 2026
@GuEe-GUI

GuEe-GUI commented Oct 15, 2026

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意思是都 EOI 了就没必要 ACK 了么？

@Xenithya

Xenithya commented Oct 15, 2026

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这个 PR 删的不是 ACK，也不是 EOI，而是旧 arm_gic_ack 在 EOI 之前多写的一笔 GICD_ICPENDR（清 pending）。这笔写是错的：处理期间若同一边沿中断源又来了新事件（典型如 NPU 先报 AXI 错误、紧接着报 done），GIC 会重新锁存 pending，这笔 ICPENDR 会把它抹掉，导致新中断永久丢失。实测：删掉它，纯中断路径 48 万次推理 0 失败；加上它，1933 次推理必现一次完成中断丢失。

@GuEe-GUI

GuEe-GUI commented Oct 15, 2026

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看了一下，arm_gic_ack 是对的，rt_hw_interrupt_ack 的用法不对，在 ISR 之后再调用会出问题，那还是建议改 traps.c 中的用法。

@Xenithya

Xenithya commented Oct 15, 2026

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arm_gic_ack() 这个名字其实有误导性——它做的是 EOI（写 GICC_EOIR），不是 ACK。GIC 的中断处理是两件事：

  • ACK（读 GICC_IAR）：在 ISR 之前，拿中断号、把 pending 转 active。这在 rt_hw_interrupt_get_irq() → arm_gic_get_active_irq() 里，已经做了，本 PR 未改动。
  • EOI（写 GICC_EOIR）：在 ISR 之后，把 active 清掉。arm_gic_ack() 在 ISR 之后被调用是正确的，EOI 本就应该在这里，不能挪到 ISR 之前。

真正的问题是：arm_gic_ack() 除了写 EOI，还多写了一笔 GICD_ICPENDR（清 pending）。这笔写个人认为既没必要（读 IAR 时 pending 已被硬件清除），又有害——ISR 执行期间若同一边沿中断源又来了新事件，GIC 会重新锁存 pending，这笔 ICPENDR 会把它抹掉，导致新中断永久丢失。

@GuEe-GUI

GuEe-GUI commented Oct 15, 2026 •
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是 ACK 的意思，只是 GIC 有两种模式，一个 EOI 模式，一个是非 EOI，RTOS通常用非 EOI 模式，所以看上去语义很奇怪，你可以看看其他操作系统比如Linux的写法。
当然这块如果修改trap.c得写法能解决问题我还是建议改trap.c的（ISR 之前 ACK 试试看是否还会有问题）：

rt-thread/libcpu/aarch64/common/trap.c

Lines 180 to 208 in 5d1fb66

ir = rt_hw_interrupt_get_irq();
if (ir == 1023)
{
/* Spurious interrupt */
return;
}
/* bit 10~12 is cpuid, bit 0~9 is interrupt id */
ir_self = ir & 0x3ffUL;
/* get interrupt service routine */
isr_func = isr_table[ir_self].handler;
#ifdef RT_USING_INTERRUPT_INFO
isr_table[ir_self].counter++;
#ifdef RT_USING_SMP
isr_table[ir_self].cpu_counter[rt_hw_cpu_id()]++;
#endif
#endif
if (isr_func)
{
/* Interrupt for myself. */
param = isr_table[ir_self].param;
/* turn to interrupt service routine */
isr_func(ir_self, param);
}
/* end of interrupt */
rt_hw_interrupt_ack(ir);

@github-actions

github-actions Bot commented Oct 17, 2026

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MemBrowse Memory Report

No memory changes detected for:

@Xenithya

Xenithya commented Oct 20, 2026

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稍等，这两天再测试一下trap.c的改法

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Arch: ARM/AArch64 BSP related with arm libcpu

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@Xenithya @GuEe-GUI