Kernel

Executive Summary Linux boot is a multi-stage handoff: UEFI → Bootloader → Kernel → systemd → Targets → Units. Each stage has failure points. This guide shows the sequence, where failures occur, and how to capture logs. Why understanding boot flow matters: When a Linux server won’t boot, you need to know WHICH stage failed to fix it effectively. A black screen could mean anything from bad hardware to a typo in /etc/fstab. …

Overview This is a one-page cheat sheet for Linux kernel subsystems. Each subsystem controls a critical resource; understanding them is essential for troubleshooting, optimization, and security. Why understanding subsystems matters: Imagine your server is slow. Without subsystem knowledge, you’re guessing: “Maybe add more RAM?” (might be CPU scheduler issue) “Maybe faster disk?” (might be memory cache problem) “Maybe more CPU?” (might be I/O scheduler misconfiguration) With subsystem knowledge, you diagnose systematically: …

Executive Summary Linux is a layered system: from firmware through kernel subsystems to containerized applications. Understanding these layers—and their interdependencies—is critical for reliable, secure, performant infrastructure. This guide covers: Layered architecture (firmware → kernel → userspace → containers) Core subsystems: process scheduling, memory, filesystems, networking systemd: unit management and service lifecycle Production best practices: security, reliability, performance, observability Note: For detailed boot flow and debugging, see the Linux Boot Flow & Debugging guide. …