macOS kernel return 31 (KERN_DEFAULT_SET): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: The request attempted to destroy Mach’s default processor set, which is system-owned.

Could be also:
Constant	Type	OS
ERROR_GEN_FAILURE	Win32 error	Windows
ippStsSmallerCodebook	Intel Ipp Status	Any
EMLINK	errno	Any
SHARED_RESOURCE_CONV_ERROR	BugCheck Code	Windows

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KERN_ALREADY_WAITING	KERN_EXCEPTION_PROTECTED

KERN_DEFAULT_SET

The protected default processor set

KERN_DEFAULT_SET is a guard on the system default processor set. It is not a signal that a processor is busy, missing, or unsuitable for scheduling; it reports that the requested destruction targets the baseline set the kernel keeps in place.

This result is most useful when reviewing low-level management code or historical Mach interfaces. The correct response is to revisit the object selected for destruction or reconfiguration, not to retry the same destructive operation.

What to inspect

Log which processor-set port was resolved and whether it denotes the default set.
Separate an operation on a custom processor set from one on the kernel-managed default set.
Preserve the preceding API result that supplied the processor-set reference.
Check the code path for stale assumptions from older Mach management APIs.

References

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