Articles

How XNU maps virtual to physical on Apple Silicon — the ARM translation regime, multi-level page tables, ASIDs that eliminate TLB flushes, and where APRR sits in the translation pipeline.

Inside the macOS sandbox — a Scheme-derived policy language, a compiler in libsandbox, and a kernel evaluator that runs on every controlled syscall.

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

The Unix-est of Unix calls, implemented on a Mach kernel. Why fork is awkward on macOS, what exec actually replaces, and why posix_spawn is now the preferred way to start a process.

The full chain from power-on to your login window. Boot ROM, iBoot, kernelcache, kernel_init, bsdinit_task, launchd — what each stage does and how control transfers.

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.

clonefile, fclonefileat, fs_snapshot — three syscalls that let you copy 50 GB in 50 milliseconds. Here's what happens under each one, and what doesn't get copied.

From a MTLCommandBuffer.commit call to the shader cores running — the userspace encoder, the kernel driver's IOConnectCallMethod, the GPU firmware processor, and where commands actually dispatch.

What changed in XNU when Apple shipped its own ARM silicon — P/E cores, APRR page-permission switching, the AMX matrix coprocessor, and Rosetta 2.