Debugging Linux Kernel in Deep - Part 2

Name: Debugging Linux Kernel in Deep - Part 2
Rating: 4.6 (133 reviews)

KGDB, KDB, GDB

Highest Rated

Created byLinux Trainer

Last updated 9/2021

English

What you'll learn

Debugging Linux Kernel Using KGDB
KGDB on Raspberry Pi3

Course content

4 sections • 41 lectures • 3h 5m total length

Introduction1:51
Hardware Requirements for Running Kgdb2:42
Hardware Setup7:51
Installing Kernel on Target9:52
Copying Kernel from Target to Development Machine4:35
Booting with gdb support4:13
Connecting to Target1:58
Connect to the target or serial port using the target command, then continue execution on the remote target to perform a backtrace and debug the kernel.
Disabling Kernel Address Layout Randomization3:21
Disable kernel address space layout randomization to reveal function addresses during debugging. Use the no casula flag on the target machine, observe backtrace and breakpoint behavior.
Adding breakpoint1:51
Switching to debugging mode5:07

Enabling KGDB at runtime3:40
learn how to enable kgdb at runtime by configuring the serial port baud rate and sending the magic sequence to switch the target into debugging mode, enabling remote kernel debugging.
TUI Mode3:04
Breakpoints for creating and deleting directories6:05
Setting breakpoints at a particular line2:08
Learn to set breakpoints on a specific line with the syntax break <target>, line number, then run and continue to verify execution at that line; delete breakpoints as needed.
What happens when you modify kernel code10:33
What happens when you use a single serial port for console and kgdb6:10
agent-proxy6:02
kgdbcon6:12
kgdbreboot3:27
Breakpoint for OOM7:03
Enabling Pretty print4:51
What happens on Panic9:23
Printing Variables6:31
Learn to print and inspect kernel variables during debugging, using breakpoints and global symbols to verify values on the target machine, while noting that local variables cannot be printed.
Setting Variables3:57
Debugging Connection Problems3:23
Breakpoint on proc cmdline2:41
Debugging In tree modules6:35
Copy the target build, load module symbols with the text segment address, and use breakpoints in the in-tree module to trace packet transmission during kernel module debugging.
Breakpoint at interrupt handler1:41
Set a breakpoint at the interrupt handler and observe the function execution on the target. Single-step through the interrupt handler and inspect AC to learn debugging interrupts with breakpoints.
GDB Scripts8:23
lx-symbols2:47
lx_current2:19
Debugging out of tree modules10:29
Debugging init and exit section of module5:20
Debug the init and exit sections by setting breakpoints in kernel/module.c, loading the module on the target, and stepping through module load and delete module cleanup.

Building image with required kernel configuration4:10
Build an image for the Raspberry Pi 3 with the required kernel configuration, update the kernel config, enable the serial port, and deploy the image.
Build and install SDK3:55
Build and install the sdk by generating a toolchain that includes gdb and the dcc compiler, then install the sdk tailored for the rba image.
Flash Image on Target1:23
Flash a downloaded image onto an SD card for the Raspberry Pi 3 via a VM, then connect the serial port to complete the setup.
Connect Serial Port1:43
Connect the serial port to the Raspberry Pi, set the baud rate to 1150 with minicom or screen, and verify the flashed image and module presence.
Run Agent Proxy1:40
Set up an agent proxy to share a single serial port among the console and devices, using localhost and designated ports on the Raspberry Pi 3.
Connect to Raspberry Pi3 over GDB4:21
Listing Source Code2:00
Configure gdb for Linux kernel debugging by setting substitute-path to the kernel source and pointing it to the Raspberry Pi 3 source folder, then use list to inspect lines.

Requirements

Should have basic knowledge of Linux Kernel

Description

User space processes can be debugged using gdb. With gdb you can

single-step,
stop,
resume,
put break-points,
inspect memory and variables,
look through call stack information

What if we can use gdb on running Linux Kernel.

Problem:

How can a gdb debug running kernel as it is just a user space process.

Solution:

Client/Server Architecture

User space programs can be debugged remotely using the combination of gdbserver on the target machine and gdb on the host machine/development machine.

The Linux kernel has a GDB Server implementation called KGDB. It communicates with a GDB client over network or serial port connection

In this course we will learn:

How to setup KGDB
Various ways of getting the target into development machine
Setting Breakpoints
Printing and Setting Variables
Using a single serial port for both kgdb and console messages
Getting the kernel messages in gdb window
Debugging Linux Kernel Modules (In-Tree, out of tree)
Use of GDB Scripts present in the Linux Kernel

Who this course is for:

Kernel developers interested to learn various debugging techniques

Debugging Linux Kernel in Deep - Part 2

What you'll learn

Explore related topics

Course content

Introduction to KGDB10 lectures • 43min

Advanced Kgdb23 lectures • 2hr 3min

KGDB on Raspberry Pi37 lectures • 19min

Downloads1 lecture • 1min

Requirements

Description

Who this course is for: