D388 - Guest syscalls are recorded in order, not as a presence bitmap

Status: decided Date: 2026-08-30

The first sixty-four syscalls a guest makes are recorded in call order, each with its first argument, into a lock-free fixed array; the report states both how many were kept and how many were made in total.

Why: A bitmap can say which numbers a guest asked for but never when, and whether a call happens before or after a guest gives up is often the entire question. Recording order needs no allocation and no lock, so it can run on the dispatch path (D381), and stating the total alongside what was kept keeps a truncated list from reading as a complete one.

Rejected:

• A presence bitmap: answers "which" and not "in what order", which is the question that actually needed answering.