Mach messages: ktrace_background

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osfmk/mach/ktrace_background.defs. Service/callback interface outside the ordinary kernel kobject table. Follow local sender/receiver evidence; external service bodies are not supplied by the declaration. Registration evidence: mig_e.

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IDs are computed from the explicit preprocessing profiles in the catalog guide, counting both routines and skip slots. They are not discovered from a running kernel. Each entry retains all observed names/declaration locations; the displayed fields come from the first non-skipped profile. Alternative declarations can have different fields. simpleroutine is one-way at the MIG interface level.

An interface contract block quotes the adjacent local .defs comment with whitespace normalized. Mechanism paragraphs explain selected implementation decisions. Local body links and call names identify implementation evidence; syntactic call lists are reading aids, not a proof that every listed call executes on every path. Short complete implementation bodies are included where especially useful.

Complete routine and reserved-slot catalog

670: ktrace_background_available

Notify a registered tracing client that background tracing is available.

Mechanism: The wrapper obtains the host background-tracing notification port and sends send_ktrace_background_available, releasing the right afterward and returning the send result. Missing/invalid endpoints produce failure. The receiving daemon's decision to start tracing is outside this tree. Local path.

Declarations: ktrace_background_available (server64, server32, client64, client32, libsyscall64, sender64, local64).

Fields after preprocessing (server64):

simpleroutine ktrace_background_available(
              ktrace_background_port : mach_port_t);

Implementation boundary: no same-symbol receiver body was resolved in the indexed local C/C++ implementation files. Local source occurrences to follow: osfmk/kern/ktrace_background_notify.c:53. These may be senders, wrappers or declarations; they do not establish a local receiver.