Linux From the Metal Up

To build your own Linux OS, you assemble and wire together a stack you understand: a kernel you configure and compile, a toolchain and C library you bootstrap, an init system, a userland and a bootloader. The most reliable way to learn it is a ladder. Start with a kernel plus a BusyBox initramfs under QEMU, then do Linux From Scratch 13.1, then read the kernel source with tracing tools running on a live system.

TL;DR

• The kernel is not the OS. Linux 7.3, released 18 October 2026, is one layer. A usable OS also needs a toolchain (binutils, GCC), a libc (glibc or musl), an init (systemd or BusyBox init), a userland, a bootloader and firmware. “Building your own OS” on Linux means building and integrating that whole stack.
• The current learning path has three steps. First, boot a kernel with a 30-line BusyBox initramfs in QEMU, which takes about an hour. Second, build LFS 13.1-systemd (binutils 2.47, GCC 16.2.0, glibc 2.44, Linux 7.1.8), which takes a weekend or more. Third, move to Buildroot or Yocto for embedded and reproducible builds.
• Observe the kernel; don’t just read about it. Every subsystem below comes with commands you can run on a live box: /proc, /sys, ftrace, perf, bpftrace and QEMU+GDB. Knowledge that you have checked against a running kernel is the kind that stays correct.

Version note (as of October 2026). Mainline is Linux 7.3 (released 18 Oct 2026).¹² The 7.4 merge window opened on 19 Oct 2026.³⁴ The newest stable updates are 7.2.13 and 6.18.59 (LTS).⁵ Linux From Scratch 13.1-systemd was published 1 Sep 2026.⁶ BusyBox 1.38.0 was released 13 May 2026.⁷ Buildroot 2026.08 and Yocto Project 6.0 “Wrynose” (LTS) are the current embedded build systems.⁸⁹ All of these move. Check kernel.org/releases.html and the LFS news page before you copy version numbers.