Linux Kernel Mastery: Design Principles & Case Studies – COMING SOON

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About Course

Master Linux Kernel Development Through Real-World Bug-Driven Learning

This is not a traditional theory-based kernel course. You’ll learn Linux kernel internals by analyzing, reproducing, and fixing real production bugs from kernel.org bugzilla. Every concept is taught through actual kernel issues, giving you practical skills that directly translate to professional kernel development.

Core Learning Methodology

Bug-Driven Kernel Mastery

  • Learn kernel subsystems by studying real bugs that affected production systems
  • Understand why kernel code is designed a certain way by analyzing actual issues
  • Develop deep intuition for kernel architecture through hands-on bug analysis
  • Build a portfolio of kernel patches as you progress through the course

Complete Bug Resolution Workflow

For every kernel bug covered, you will:

  1. Analyze – Study the bug report and understand the problem
  2. Explore – Navigate kernel source code to find relevant subsystems
  3. Reproduce – Use provided VM images or build custom reproducers
  4. Instrument – Add logging and tracing to understand execution flow
  5. Fix – Study the upstream patch and understand the solution
  6. Test – Validate the fix in isolated environments
  7. Document – Create visual diagrams and detailed analysis
  8. Contribute – Learn to submit patches following kernel standards

While bugs are continuously added, you’ll gain expertise across major kernel areas:

Core Subsystems

  • Memory Management (MM subsystem)
  • Process Scheduling and Task Management
  • Virtual File System (VFS) and File Systems
  • Networking Stack (TCP/IP, packet handling)
  • Block Layer and Storage
  • Device Drivers and Hardware Interaction
  • System Calls and Kernel Entry Points
  • Locking and Synchronization Mechanisms

Fundamental Concepts

  • User space vs kernel space architecture
  • Virtual memory and address space management
  • Interrupt handling and bottom halves
  • Kernel threading and work queues
  • Reference counting and object lifecycle
  • Error handling and resource management
  • Hardware abstraction and platform support
  • Boot sequence and initialization

Advanced Topics

  • Race conditions and concurrency bugs
  • Memory corruption and use-after-free issues
  • Performance bottlenecks and optimization
  • Security vulnerabilities and hardening
  • Compatibility and regression issues
  • Cross-architecture considerations
  • Kernel configuration and build system

 

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What Will You Learn?

  • Learn kernel subsystems by studying real bugs that affected production systems.
  • - Why certain design decisions were made
  • - What edge cases developers must consider
  • - How subsystems interact in unexpected ways
  • - Common pitfalls in kernel development
  • - Best practices validated by production experience

Course Content

VM Setup – Enabling copy paste & Creating Shared Drive

  • DOC

Linux Kernel Issues List

Linux kernel – Complete System Call Flow Analysis
Introduction A Deep Dive into Linux x86-64 System Call Mechanism Part 1: User Space to Kernel Transition Step 1: Your C Program (test_syscall.c) User space invocation (Ring 3) syscall() wrapper function call Example: Custom syscall number 463 Step 2: GCC Compilation to Assembly Compilation process: gcc -S test_syscall.c Generated assembly analysis Register argument preparation (RDI, RSI, RDX) PLT (Procedure Linkage Table) mechanism Dynamic linking with glibc Step 3: GOT Resolution Process PLT.sec entry and GOT (Global Offset Table) Dynamic symbol resolution _dl_runtime_resolve operation Lazy binding mechanism Finding glibc's syscall() function Step 4: Glibc syscall() Wrapper Location: /lib/x86_64-linux-gnu/libc.so.6 Register shuffling for kernel ABI Argument placement (RAX, RDI, RSI, RDX, R10, R8, R9) The syscall instruction (0x0f 0x05) Part 2: Hardware-Level Privilege Transition Step 5: The syscall Instruction (Hardware Magic) CPU atomic operations State preservation (RIP→RCX, RFLAGS→R11) MSR (Model-Specific Register) configuration MSR_STAR: Segment selectors MSR_LSTAR: Kernel entry point MSR_SYSCALL_MASK: Flags to clear Privilege switch (Ring 3 → Ring 0) CPL (Current Privilege Level) change MSR Configuration Deep Dive syscall_init() function wrmsrl() implementation chain wrmsrl() wrapper native_write_msr() with tracing __wrmsr() raw instruction WRMSR assembly instruction breakdown Boot-time MSR setup Part 3: Kernel Entry and Execution Step 6: Kernel Entry Point (entry_64.S) File: arch/x86/entry/entry_64.S entry_SYSCALL_64 function swapgs instruction (GS register switch) Stack switching (user→kernel) Register saving on kernel stack pt_regs structure creation Call to C dispatcher: do_syscall_64 Step 7: System Call Dispatcher (common.c) File: arch/x86/entry/common.c do_syscall_64() function flow Stack offset randomization syscall_enter_from_user_mode() do_syscall_x64() implementation Bounds checking and security validation Step 8: System Call Table Lookup Generated file: arch/x86/include/generated/asm/syscalls_64.h Macro expansion mechanism __SYSCALL() macro processing Switch-case generation x64_sys_call() dispatcher Finding syscall handler: __x64_sys_hello Step 9: Your Syscall Executes (hello.c) Custom syscall implementation SYSCALL_DEFINE0(hello) macro Kernel logging with pr_info() Return value to user space Part 4: Return Journey to User Space Step 10: Syscall Exit Path Return value propagation syscall_exit_to_user_mode() function __syscall_exit_to_user_mode_work() Syscall-specific cleanup Interrupt disabling Pending work handling Interrupt Disabling Deep Dive local_irq_disable() macro native_irq_disable() implementation CLI instruction (asm volatile("cli")) RFLAGS interrupt flag clearing Why interrupt disabling is critical Step 11: The sysretq Instruction x86-64 return mechanism Hardware operations (atomic) RIP ← RCX (return address restoration) RFLAGS ← R11 (flags restoration) CS ← MSR_STAR[63:48] + 16 (user code segment) CS.RPL ← 3 (Ring 3 privilege) SS ← MSR_STAR[63:48] + 8 (user stack segment) SS.RPL ← 3 (Ring 3 privilege) CPL ← 3 (user mode switch) Linux Segment Selectors Kernel segments: __KERNEL_CS (0x10), __KERNEL_DS (0x18) User segments: __USER_CS (0x33), __USER_DS (0x2B) CPL encoding in segment selectors Ring 0 vs Ring 3 comparison table MSR_STAR Segment Calculation MSR_STAR register layout (64-bit) SYSRET CS base selector CS = MSR_STAR[63:48] + 16 calculation SS = MSR_STAR[63:48] + 8 calculation Example: 0x23 + 16 = 0x33 (__USER_CS) Part 5: Return to User Space Step 12: Return to Glibc Glibc syscall() return point (0x130fdd) Error checking logic Comparison with 0xfffffffffffff001 Error code range (-4095 to -1) errno setting on failure Success path: direct return Return instruction to test_syscall.c Step 13: Complete Flow Verification Expected output demonstration Live system proof Kernel log verification with dmesg Success confirmation

Understanding Linux Kernel Module & Module programming.
Topics Covered » Building Custom Kernel Modules from Scratch » How insmod Loads a Module (Step-by-Step Inside the Kernel) » The Kernel Module Linked List (How Modules Live in Memory) » How lsmod Reads and Displays All Loaded Modules » How rmmod Safely Removes a Module » Writing a Module that Replicates lsmod Output » Modifying Kernel Source (module.c) to Trace insmod Stages in Real Time » Real-World Compatibility: Kernel 3.9.0 API Differences

Linux Kernel – Analyzing Crash Dump – Ex: 218536
https://bugzilla.kernel.org/show_bug.cgi?id=218536

Case Study 1 – Huge Page

Case Study 2 – OOM Killer
OOM Killer

Case Study 3 – Memory Management Deep Dive

Case Study 4 – Bug 60665 – TCP Backlog Overflow Fix
Bug Details Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=60665 Summary: int backlog is assigned to unsigned short sk_max_ack_backlog causing overflow

Case Study 5 – Bug 209949 – swap is not activated
With kernel 5.10 RC 1, swap is not activated, swapon says "file is not commited".

Case Study 6 – What is User Space and Kernel Space ? What Actually Makes “User Space “User Space”

Case Study 7 – How does the kernel discover the hardware?

Case Study 8 – Core Memory Management Initialization

Case Study 9 – Memblock Allocator Guide Reference Kernel 5.15.0-rc1

Case Study 10 – PCI Device Discovery in Linux Kernel

Case Study 11 – System.map – Everything You Need to Know About Linux Kernel Symbol Tables

Case Study 12 – The Complete Linux Kernel Boot Sequence

Case Study 13 – Networking – Bug 211911: Panic in skb_find_text()

Case Study 14 – Understanding Linux Audio Sub System and Audio Driver

Case Study 15 – What is Perf tool – How it works – All about perf

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FAQs (One-Line Answers)

We offer live online classes (₹85,000) on weekends and recorded video lectures (₹35,000 with lifetime access) - no offline classes currently.

Strong C programming skills and basic familiarity with Linux command-line/systems are required.
Live weekend classes (Saturday & Sunday) via Zoom/Google Meet for 8-9 months (180 hours total), with all sessions recorded for revision.
180 hours across 8-9 months with weekend sessions (Saturday & Sunday), covering 5 modules from system programming to kernel debugging.
Lifetime access to all recorded live class sessions (₹35,000) - learn at your own pace with the same content as live classes.
Yes, practical sessions include Raspberry Pi, BeagleBone, QEMU virtual machines, and real peripherals (I2C, SPI, GPIO devices).
Yes, you can upgrade by paying the differential amount - contact support for upgrade options.
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