Linux & Kernel

How Linux actually works, from the boundary between a command you type and the kernel that services it, down to page-table walks, RCU grace periods, and the path a packet takes through the network stack. The aim is understanding you can reason from — not commands you have memorised.

This section is being written

Folders and pages exist as stubs so the structure and its dependency graph are navigable from the start.

The pinned kernel

Every source reference in this section points at Linux v6.18 — released 2025-11-30, a longterm release with projected end-of-life in December 2028. Citations name a file and a symbol (fs/namei.c:path_openat()) and never a line number, because line numbers rot within a single release while paths and symbol names survive for years.

Where behaviour changed recently enough that older material is now wrong — the fair scheduler, the folio conversion, io_uring — the page says so explicitly.

The lab

Nearly every hands-on exercise runs against a kernel you build yourself, booted under QEMU. A kernel panic there costs you nothing and you can attach a debugger to the virtual CPU itself. Setting Up a Lab covers the whole setup, including what WSL2 can and cannot do.

See the roadmap for the dependency graph and the learning paths through everything here.