user
86 lines
2.7 KiB
Markdown
86 lines
2.7 KiB
Markdown
# K08 — dynamic/static task storage, deletion and lifetime
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K08 gives identical worker behavior two storage policies:
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- `DynamicTask` calls `xTaskCreate`; FreeRTOS allocates TCB and stack from
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`heap_4` and the idle task later reclaims them after self-deletion;
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- `StaticTask` calls `xTaskCreateStatic` with caller-owned `StaticTask_t` and
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`StackType_t[]` located in `.bss`; task deletion never transfers ownership of
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those buffers to the kernel.
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Both wrappers remain non-copyable, non-movable and non-virtual. The static
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storage is a separate `StaticTaskStorage<N>` object so its TCB/stack are visibly
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caller supplied and their lifetime is independent from the wrapper's handle.
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## Measured Hazard3 result
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```text
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dynamic heap cost = 0x470 = 1136 bytes
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free before idle cleanup = 0x3b80
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free after idle cleanup = 0x3ff0 (baseline)
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static stack words = 0x100 = 256
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static stack bytes = 0x400 = 1024
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```
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The dynamic worker sets `completed` and clears its wrapper handle before
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`vTaskDelete(nullptr)`, but its kernel storage is only placed on the termination
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list at that point. A static verifier first captures the reduced heap, blocks
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for two ticks to let idle run, then observes full recovery.
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## Evidence
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| Stage | Heap relation |
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| --- | --- |
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| baseline | initialized `heap_4`, no worker kernel object |
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| dynamic start | free decreases by 1136 B |
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| static start | free unchanged from dynamic-start value |
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| static verifier create | free unchanged again |
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| workers completed/self-deleted | dynamic 1136 B still not reclaimed |
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| verifier blocks, idle cleans | free increases by 1136 B to baseline |
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Addresses prove dynamic TCB/stack lie in `ucHeap`, while the static TCB and
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stack equal the caller storage addresses in `.bss`. Both workers compute
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500500.
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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:
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```text
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PASS host: dynamic/static policies, stable caller storage and units
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PASS ABI: dynamic/static trampolines; caller storage in .bss; no vtable
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PASS task01: dynamic/static task storage + idle cleanup
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```
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## Debug
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```gdb
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b task_storage_debug_checkpoint
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p g_heap_baseline
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p g_heap_after_dynamic_start
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p g_heap_after_static_start
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p g_heap_before_idle_cleanup
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p g_heap_after_idle_cleanup
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p/x g_dynamic_tcb
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p/x g_dynamic_stack_low
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p/x g_static_tcb
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p/x g_static_tcb_storage
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p/x g_static_stack_low
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p/x g_static_stack_storage
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p g_static_stack_words
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p g_static_stack_bytes
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p g_task_storage_pass
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```
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## Scope boundary
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Task deletion does not safely unwind arbitrary application resources on its
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stack. The workers arrange normal member completion before self-deletion. Static
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storage must outlive the task and must not be reused merely because a stop was
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requested; completion/deletion must be established first.
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