Document source: e47887d3a11f; code reference: e47887d3a11f. 中文. Source language: en; requested: en; actual: en; translation: original.

Source documentation does not establish software or physical hardware qualification. See the support and qualification records for their exact scope.

Borrow, completion and observer lifetime

The caller owns request and buffer storage. Accepted asynchronous I/O borrows it; rejection does not. Cancellation, a deadline or a failed stop cannot revoke that borrow. This separation prevents IRQ/DMA or an executor from accessing recycled memory. The lifecycle contract and public operation declarations define exact context and result behavior.

Event	Storage consequence
Rejected admission	No retained request/buffer references or residual hardware effects
Accepted admission	Keep request and buffers valid until acquire-observed SETTLED
Cancel or deadline	Request termination; continue required progress and retain borrow
DMA completion	Memory engine stage complete; wire/publisher references may remain
Failed drain / QUARANTINED	Keep storage and explicit recovery responsibility
SETTLED publication	Provider’s final access has ended after necessary reference drain
Observer/control reuse	Also detach/drain matching epochs and join observers

FIG-06 does not treat REJECTED/ACCEPTED as request-state enum members. Core helpers cannot observe a peripheral’s physical drain; the provider must establish that proof before publishing settlement.

Execution contexts and shutdown ownership

Operation group	Execution owner	Required lifetime and progress
Direct request admission and service	One serialized executor in the public operation’s permitted context	Keep admitted request and buffers through acquire-observed SETTLED; explicit service advances deadline and drain
Fixed provider IRQ	The selected vector and its declared IRQ policy	Record bounded hardware facts; retain every reference until the provider proves withdrawal
Cross-task producers or cancellation	An explicit owner/adapter using stable slots and epochs	Drain controls and join observers before recycling operation or adapter storage
Waiting	The caller with an explicit wait/wake port	Check readiness, arm, recheck, wait and recheck the authoritative predicate; a hint alone does not settle a request or service hardware
Platform start and stop	One external lifecycle owner	Quiesce callers and publishers, keep cleanup progressing and retain remaining effects after BUSY or failure

Atomic publication of request state does not serialize accesses to other request fields or payload buffers, or permit competing admission owners. Use the public operation contract and an explicit shared owner when multiple tasks access a controller. Platform stop does not revoke a static face or automatically stop product tasks.

Three different completion facts

FIG-07 separates memory completion, wire completion and final publication. UART TC is not NDTR zero; SPI idle and CS interval are not a DMA interrupt. Disable and detach the actual IRQ/DMA/queue references before release-publication of SETTLED. The caller’s acquire observation then exposes the final result/count. A timeout result can be final only after this lifecycle, not at deadline expiry.

Cross-task control and continuous streams

Use stable slots plus monotonically increasing epochs for remote control. Do not send a raw pointer to storage another task can recycle. Detach control/observer references and join observers before releasing the slot and preparing the next request. A generation counter detects stale identity but does not itself join a task.

Continuous receive and ADC use explicit caller-owned block loans. A consumer keeps a block immutable until matching release. The producer needs a replacement target before publishing an old hardware bank. No replacement means visible stop/backpressure; it must never overwrite a consumer. Stop waits for filling, ready and borrowed blocks, not just active DMA. The stream contract records what loss counters and software timestamps do and do not prove.

FIG-15 includes observable loss and stop/drain responsibilities. Capacity and service-latency budgets are explicit product inputs; arbitrary IRQ delay or consumer speed cannot be promised lossless. The tutorial executes rejection and quarantine; OS shutdown explains wait and join responsibilities.