user
90 lines
2.7 KiB
Markdown
90 lines
2.7 KiB
Markdown
# K07 — `TaskHandle_t`, explicit `start()` and static trampoline
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K07 isolates the exact C/C++ task-entry boundary. A local `CounterTask` object
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is constructed without touching the FreeRTOS heap. Only an explicit `start()`
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calls `xTaskCreate()` and passes the stable object address as `void*` context.
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The kernel later calls a static, non-virtual trampoline, which recovers the
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typed object and invokes its private `run()` member.
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```text
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CounterTask object
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-> start()
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-> xTaskCreate(static trampoline, context=&object)
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-> kernel chooses task
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-> trampoline(void*)
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-> static_cast<CounterTask*>(context)
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-> object.run()
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-> state=completed, handle=nullptr, vTaskDelete(nullptr)
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```
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The wrapper is non-copyable and non-movable because a live kernel task retains
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its object address. The destructor does not attempt asynchronous task deletion.
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## Three distinct address domains
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The checked Hazard3 run records:
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```text
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C++ object = 0x800fffcc (local object on the retained main stack)
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TCB/handle = 0x800038b0 (dynamic kernel object in ucHeap)
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task stack = 0x800034a0..0x80003890
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result = 500500
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```
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The object address remains identical before start, in `xTaskCreate` context,
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inside the trampoline, inside `run()` and at completion. The numeric handle is
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the TCB address and is deliberately different from the C++ object.
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## Lifecycle evidence
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| Point | Evidence |
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| --- | --- |
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| 1 | object constructed; heap unchanged; handle null |
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| 2 | state `starting` inside explicit start |
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| 3 | state `ready`; typed object passed as raw context |
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| 4 | `xTaskCreate` returned; handle now identifies the TCB |
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| 5 | scheduler not yet started; object still at same address |
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| 6 | static trampoline receives the original object address |
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| 7 | state `running` before member body |
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| 8 | body records current handle, stack bounds and result |
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| 10 | state `completed`, handle cleared, current task self-deletes |
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| 11–12 | raw verifier checks identity/lifecycle and emits PASS |
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## Build
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```sh
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make check
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```
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Expected summary:
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```text
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PASS host: explicit start, stable context, duplicate/failure states
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PASS ABI: static trampoline; no vtable, RTTI or hosted runtime
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PASS task01: explicit start + stable context + trampoline
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```
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## Debug
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```gdb
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b explicit_task_debug_checkpoint
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p g_checkpoint_trace
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p/x g_object_before_start
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p/x g_trampoline_context
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p/x g_run_this
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p/x g_handle_after_start
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p/x g_tcb_address
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p/x g_stack_low
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p/x g_stack_high
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p/x g_stack_local
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p g_counter_result
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p g_task_wrapper_pass
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```
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## Scope boundary
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K07 uses dynamic kernel storage only to study entry and identity. K08 compares
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dynamic and caller-supplied static TCB/stack policies and the timing of idle-task
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cleanup. A `Task` destructor still does not force-delete a running task.
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