Tagged: #mach

Spinlocks, mutexes, reader-writer locks, and lock-class groups — the synchronization primitives XNU offers, when each is appropriate, and how the per-CPU caches stay fast under contention.

From the moment an interrupt fires to the moment a different thread is running on the core — trap, AST, thread_invoke, ASID switch, return.

Inside a Mach message: how it's allocated, queued, woken on, and copied. Plus vouchers — the QoS-and-resource-propagation system most people don't notice.

The path from a kernel panic to a stack trace — the panic handler, the KDP wire protocol, attaching lldb to a panicked kernel, and what's recoverable on a live system.

Real-time, fixed-priority, timeshare, idle — four scheduling classes, 128 priorities, and a QoS layer on top. Here's how XNU picks a thread to put on a core.

Tasks, ports, messages, and rights — the IPC primitive that quietly carries every IPC on your Mac, from XPC to drag-and-drop.