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kIOFWMessageServiceIsRequestingClose
kIOFWMessageServiceIsRequestingClose notifies a client that the FireWire service is requesting closure. It is a lifecycle message, not a transfer failure, so outstanding I/O and client resources should be quiesced through the normal close path.
First returning layer
IOKit return values, internal tokens, and service messages share an integer representation but not the same control-flow meaning. Determine whether the API returns the value or delivers it as a message before treating it as failure.
Evidence map
| Capture | Diagnostic value |
|---|---|
| Service registry entry, client connection, message timestamp, open count, and outstanding requests. | Identifies the concrete object and operation associated with FireWire service close-request message. |
| Numeric IOReturn/message value decoded with the matching SDK header. | Separates argument or lifecycle state from the provider beneath kIOFWMessageServiceIsRequestingClose. |
| Registry generation and first provider/client event before the result. | Correlates the close request with the service generation and provider/client event that preceded it. |
| Known-good device or service state on the same macOS/driver build. | Shows whether kIOFWMessageServiceIsRequestingClose is the first result or a translated summary. |
Change one condition at a time
- Acknowledge/close a disposable client after receiving the message.
- Change one topology or lifecycle condition while keeping the request payload fixed.
- Verify cleanup and object lifetime after the controlled operation.
Repair and regression test
Targeted correction. Quiesce I/O, release user-client resources, and close through the documented message handler.
Acceptance criterion. The client closes without leaked opens and later reopen follows a fresh service generation.
Technical references
- Apple XNU: IOReturn definitions — defines the status namespace used.
- Apple: IOKit documentation — documents the API or lifecycle boundary behind it.
- Apple OSS: XNU source — provides ABI, implementation, or protocol context.
- Apple XNU: FireWire family common definitions — supports the portability and verification limits.
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