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KERN_SUCCESS
For successful Mach kernel primitive, the numeric result becomes useful only when tied to the exact operation and object state. KERN_SUCCESS is zero in the kern_return_t namespace and reports successful completion of the Mach kernel interface that returned it. The result validates the call-level contract; callers must still inspect output counts, returned rights, and object state defined by that specific routine.
Operational meaning
Several Apple low-level APIs use zero for success, but each typedef belongs to a distinct contract for the successful Mach kernel primitive case. The return type, output validation, and resource ownership rules remain part of successful handling while evaluating successful Mach kernel primitive.
KERN_SUCCESS is not a universal success token for POSIX, IOKit, or Mach messaging. A zero integer returned through errno, IOReturn, or mach_msg_return_t belongs to a different contract even when its bit pattern is identical. Keep the numeric value, declared return type, and first returning operation together with KERN_SUCCESS; the same integer can belong to a different status namespace in another API.
Build a reproducible record
| Capture | Diagnostic value |
|---|---|
| The MIG routine or Mach kernel call, its subsystem interface, and the exact kern_return_t value. | Identifies the concrete object and operation associated with successful Mach kernel primitive. |
| Input and output port names together with the right types held before and after the call. | Separates argument or lifecycle state from the provider beneath successful Mach kernel primitive. |
| Returned counts, flavor selectors, structure versions, and buffer sizes used by the routine. | Creates a stable before-and-after comparison for successful Mach kernel primitive. |
| Task, thread, host, or memory-object identity and the lifecycle event immediately following success. | Shows whether successful Mach kernel primitive is the first result or a translated summary. |
For successful Mach kernel primitive, preserve the MIG routine or Mach kernel call, its subsystem interface, and the exact kern_return_t value before reinstalling, rebooting, clearing state, or substituting another device or provider. A success observed only after such a change is useful comparison data for successful Mach kernel primitive, but it does not identify the original cause.
Checks that separate the causes
- Repeat the routine with one intentionally invalid right or flavor and verify a nonzero kern_return_t is returned. Keep unrelated inputs fixed so the change remains attributable to successful Mach kernel primitive.
- Validate the output count before reading variable-length data supplied by the kernel. Record the first returned status and any state transition observed during successful Mach kernel primitive.
- Deallocate or transfer every returned Mach right according to the routine contract and check for right leaks. Treat a changed result as a new boundary rather than automatic resolution of successful Mach kernel primitive.
Interpret the comparison
| Observed comparison | Next conclusion to test |
|---|---|
| The first control changes the result | Concentrate on the variable isolated by this check: Repeat the routine with one intentionally invalid right or flavor and verify a nonzero kern_return_t is returned. |
| The second comparison for successful Mach kernel primitive reproduces the same first status | Preserve lower-layer provider, driver, service, or runtime evidence before editing application data. The second controlled check was: Validate the output count before reading variable-length data supplied by the kernel. |
| A different status replaces successful Mach kernel primitive after the bounded change | The operation moved to another boundary after the third controlled check. That check was: Deallocate or transfer every returned Mach right according to the routine contract and check for right leaks. Retain both results and interpret the replacement through its own API contract for successful Mach kernel primitive. |
Resolution criteria
Targeted correction. Preserve the routine-specific validation and ownership checks after KERN_SUCCESS instead of collapsing every zero kern_return_t into one generic success path. For successful Mach kernel primitive, modify only the object, argument, policy, provider, or lifecycle state identified by the collected evidence.
Acceptance criterion. The Mach routine returns KERN_SUCCESS, all output counts and rights match the interface definition, and repeated execution leaves no leaked or unexpectedly consumed rights. Re-run the original operation that produced successful Mach kernel primitive under its original identity and supported configuration, then keep one negative control that still produces the expected neighboring outcome.
Technical references
These owner-maintained or standards-based sources define the namespace and subsystem contract needed to verify KERN_SUCCESS on the deployed platform version.
- Apple XNU: kern_return_t definitions — defines the status namespace used for successful Mach kernel primitive.
- Apple: Mach overview — documents the API or lifecycle boundary behind successful Mach kernel primitive.
- Apple XNU source repository — provides ABI, implementation, or protocol context for successful Mach kernel primitive.
- Apple XNU: Mach message definitions — supports the portability and verification limits for successful Mach kernel primitive.
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