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kOSReturnError
Investigate generic Libkern operation failure at the first returning call, before a wrapper substitutes a generic message. Libkern returned its generic error value because no more specific OSReturn code was supplied at that boundary.
Read the status in context
IOKit results, internal tokens, and service messages cross user space, kernel services, and hardware families. Their integer representation does not make their control-flow roles interchangeable.
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. Keep the numeric value, declared return type, and first returning operation together with kOSReturnError; the same integer can belong to a different status namespace in another API.
Diagnostic facts
| Capture | Diagnostic value |
|---|---|
| Returning class/method, object registry path, provider, operation arguments, and preceding IOKit log. | Identifies the concrete object and operation associated with generic Libkern operation failure. |
| Numeric IOReturn/message value decoded with the matching SDK header. | Separates argument or lifecycle state from the provider beneath this result. |
| Registry generation and first provider/client event before the result. | Creates a stable before-and-after comparison. |
| Known-good device or service state on the same macOS/driver build. | Shows whether this result is the first result or a translated summary. |
Preserve known-good device or service state on the same macOS/driver build while evaluating this result before reinstalling, rebooting, clearing state, or substituting another device or provider. A success observed only after such a change is useful comparison data, but it does not identify the original cause.
Verification path
- Invoke the smallest supported method on a known-good provider object. Repeat the original supported operation so the check remains relevant to this result.
- Change one topology or lifecycle condition while keeping the request payload fixed. Keep unrelated inputs fixed so the change remains attributable to this result.
- Verify cleanup and object lifetime after the controlled operation. Record the first returned status and any state transition observed.
What the result does not prove
| Observed comparison | Next conclusion to test |
|---|---|
| The first control changes the result | Concentrate on the variable isolated by this check: Invoke the smallest supported method on a known-good provider object. |
| The second comparison for this result reproduces the same first status | Preserve lower-layer provider, driver, service, or runtime evidence before editing application data. The second controlled check was: Change one topology or lifecycle condition while keeping the request payload fixed. |
| A different status replaces this result after the bounded change | The operation moved to another boundary after the third controlled check. That check was: Verify cleanup and object lifetime after the controlled operation. Retain both results and interpret the replacement through its own API contract. |
Closing the incident
Targeted correction. Fix the first provider-specific failure and preserve the generic wrapper as secondary evidence. Modify only the object, argument, policy, provider, or lifecycle state identified by the collected evidence.
Acceptance criterion. The operation returns a specific success/failure and the generic code no longer masks the underlying event. Re-run the original operation that produced this result under its original identity and supported configuration, then keep one negative control that still produces the expected neighboring outcome.
Technical references
References for kOSReturnError on the deployed platform version.
- Apple XNU: IOReturn definitions — defines the status namespace used.
- Apple: IOKit documentation — documents the API or lifecycle boundary behind this result.
- 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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