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Linux Kernel Integration Guide

Language: English (default) | Русская версия

This file is still named MIGRATION.md for backward compatibility. It now documents Linux kernel integration in K1OS, not a one-time migration effort.

K1OS Positioning

K1OS is a Linux-based operating system.

Linux kernel is used as the base system layer so we can:

  • avoid spending years on writing a new kernel from scratch;
  • rely on mature kernel subsystems and driver support;
  • focus K1OS engineering effort on boot flow, rootfs, user space, and tooling.

Responsibilities: Kernel vs K1OS

Linux kernel layer:

  • hardware and driver management;
  • scheduler, memory, networking, and system interfaces.

K1OS layer:

  • boot architecture (initramfs -> squashfs -> overlayfs -> switch_root);
  • rootfs and userland composition;
  • package management via warp;
  • ISO build and delivery pipeline.

Current Integration Flow

1. Kernel Maintenance

  • Update/pin kernel version in kernel/.
  • Keep changes minimal relative to upstream.
  • Validate required options for K1OS (for example squashfs/overlayfs/block device support).

2. Boot Pipeline Integration

  • Stage 1 (rootfs/init) mounts virtual filesystems and locates system.squashfs.
  • Stage 1 configures overlayfs with either:
    • persistent ext4 partition (label K1OS-DATA), or
    • tmpfs for RAM mode.
  • switch_root transfers control to stage 2 (/sbin/init).

3. User Space and Packages

  • User space components are built through packages/*/build.sh.
  • Base utilities are assembled into rootfs/.
  • warp is used as the native K1OS package manager.

4. Validation

  • Validate ISO boot in both RAM and persistent modes.
  • Validate service startup and shell environment.
  • Ensure changes do not break boot path or rootfs compatibility.

Build Commands

# Kernel
make kernel

# RootFS + packages
make rootfs

# ISO
make iso

# Full build
make all-build

# QEMU (RAM / persistent)
make qemu
make make-persist
make qemu-persist

Kernel Change Rules

  • Patch the kernel only when needed for K1OS-specific goals.
  • Every kernel change must document rationale and boot/user space impact.
  • Prefer upstream-aligned configuration and integration over a deep kernel fork.

License

The project uses Apache License 2.0. New code and dependencies must be license-compatible.