COURSE OBJECTIVES

• To get real-world exposure to embedded Linux
• To develop an application to run on an embedded Linux system
• To understand what is required to set-up a Linux cross development environment
• To understand the different approaches to making Linux “realtime” Delegates will learn:
• How to configure a standard Linux kernel for use in a cross development system.
• The steps to write, compile, download and debug an embedded Linux application with real hardware.
• How threaded applications fit into Linux.
• How drivers work in x86 and embedded environment.

PRE-REQUISITES

•  Good ‘C' programming skills.

•  Required considerable knowledge of Linux System Programming concepts like signals, processes, file operations, system calls and sockets which are covered in our “Workshop 1 : Linux Internals & Programming Essentials Course”.

 

Days

3 days

 

COURSE CONTENTS

Embedded Linux System Development

• Introduction to Embedded Linux ( Obisense )

•  What is Embedded System?

•  Anatomy of an Embedded System

•  Why Linux?

•  Is Linux Real-Time Enough?

•  The Status of Embedded Linux Today

•  Which Embedded Linux Distribution to Choose?

•  Embedded Linux Architecture

• Basic requirements for Embedded Linux Product Development
  - The four basic elements: toolchain, bootloader, kernel, root file system

- Configuration, compilation and cross-compiling

• Building Development Environment ( Obisense )

- Toolchain installation

- Cross compilation using Toolchain

• Target & Host Setup

• Setting Up Networking Services

- Network Settings

•  Static and Dynamic IP addresses

•  Subnet mask

- Setting up services

•  TFTP

• DHCP
• HTTP
• FTP etc
• SNMP
• Telnet
• SSHD

- loading files using TFTP, HTTP, FTP etc.

•  Bootloader commands and usage

- Getting familiar with bootloader commands

- Downloading kernel images and RootFS on Target board.  

• Loading RootFS in Platfrom by various techniques -

- Configuring TFTP and downloading kernel image over TFTP.

- Configuring NFS and using rootfs over NFS.

- Using SD-Card for rootfs.

- Using USB for rootfs.

• Building an Embedded File System from Scratch -

- Creating a minimal root file-system using Busybox

- Creating a RAM disk image

• Building Your Own Embedded Linux Distribution -

- Buildroot

- Scratchbox

- OpenEmbedded

- Crosstool

- Angstrom – narcissus

• Kernel Configuration and Compilation

- Kernel Building System

- Patching the Kernel

- Kernel Configuration for Embedded Systems Settings (Porting)

- Cross-compiling the Linux Kernel

•  Booting Linux
- The Linux boot sequence
- boot-loaders : U-boot

- System Initialization Scripts

•  Bring up X11 (X-Windows) on Embedded Platform (GUI)

•  Loading various RootFS (Distributions) in platform

•  Angstrom

•  Ubuntu

•  Fedora etc. RootFS

Linux Device Driver Programming

•  An introduction to device drivers
- User space vs Kernel space

- Kernel Architecture or Model

- Splitting the kernel

- Kernel modules

- Kernel Module vs Applications

- Role of the Device Drivers

- Classes of devices and modules

•  Kernel Module Programming Basics

- Modules Defined

- Data Type in the Kernel

- Version dependency

- Building and Running Modules

- Types of Modules in the kernel

- Writing Your first kernel module

- Module Related Commands

- Statically linked vs Dynamically linked drivers/modules

- The kernel symbol table

- Exporting symbols from modules

- Module Parameters

- Lab exercises for above mentioned topics

•  Kernel Debugging Techniques

- Kernel Debugging: dmesg, printk

- Lab exercises for above mentioned topics

•  Accessing Hardware Mechanisms

•  System Memory

•  Device Memory

•  I/O Ports

•  I/O ports vs. memory mapping

•  Allocating and mapping I/O space

•  Functions for reading and writing I/O ports

•  Side effects and compiler optimization

•  I/O APIs

•  Driver example

•  Barriers

•  Accessing hardware from User Space

•  The proc file system programming

•  Using /proc

•  Creating proc file system entries

•  Registration

•  Reading from /proc

•  Writing to /proc

•  Lab exercises

•  Communicating with Hardware

•  Using I/O Ports 

•  Example: the Parallel Port

•  Side effects and compiler optimization

•  I/O APIs

•  The hardware

•  Driver example

•  Barriers

•  Accessing hardware from User Space

•  User-Mode Access to Devices

•  open, close, read, write

•  ioctl

•  ioperm, iopl, inb, outb

•  mmap, munmap

• Hardware and Interrupt Handling

- Installing and implementing an interrupt handler

- Restrictions of kernel code running in interrupt context

- IRQs & their Registration

- IRQ Handling & Control

- Top & Bottom Halves

- Autodetecting IRQ's 

- Kernel Help in detecting IRQ's 

- Probing for the interrupt source

- Enabling and Disabling Interrupts 

- Lab exercises

•  Tasklets and Bottom halves

- Task queues

- Lab exercises

•  Kernel Threads

- Lab exercises

•  Sleep and wakeup (wait queues)

•  Buffer allocation

•  Memory Mapping and DMA

•  Direct Memory Access/Bus Mastering

•  Consistent Mapping

•  Streaming Mapping

•  Scatter/Gather Mapping

•  Memory Management

•  Allocating Memory

•  Accessing Memory 

•  Get Some Space (kmalloc()), kfree(), various flags

•  Get Some Pages  (get_free_page())

•  Get Some Virtual Memory - vmalloc()

•  Get Some Boot-time Space

• Concurrency and Race Conditions

•  UP vs SMP Issues

•  Combating Race Conditions 

•  Atomic Operations

•  Semaphores

•  Spin Locks

•  Time, Delays and Deferred Work

•  Kernel Timers

•  Timer handling

•  HZ and Jiffies

•  Time of Day

•  Delayed Execution

•  Kernel Timers

•  Current time

•  The Linux Device Model

•  Character Device Drivers
- Registering a character device driver

- The file structure

- Major and minor numbers

- Character Device Methods open(), release(), read(), write() 

- Data Transfers between User Process and Driver 

•  copy_from_user(), copy_to_user()

- Making a Device File

- Memory Access in Kernel Space

- Programming with ioctl( ), mmap()

- devfs / lseek /ioctl

- Lab exercises

•  Writing various Character Drivers

•  Memory Based Driver

•  IO PORT (Hardware) Based Driver

•  Enhanced Character Device Drivers

•  Driver and Device Control with 'ioctl()' 

•  Blocking VS Non-Blocking I/O

•  Sleep vs Wakeup 

•  poll()

•  llseek()

•  Access Control through Drivers 

•  Programming with ioctl( )

- writing device driver with ioctl()

- Adding ioctl's in an existing device driver

- Lab exercises

•  Netlink socket interface

- point to point, multicast and broadcast

- UDP, TCP and Raw sockets

- Writed kernel module and userspace applilcations using Netlink sockets

- Lab exercises

•  Network Drivers
- The net_device structure in detail

- Packet transmission

- Packet reception

- Simulating a network device

- Lab exercises

•  Block Device Drivers
- Handling requests

- Ram Disk Driver

- Block drivers structures

- Block Device Driver Registration

•  Block Device Operations & its related Kernel DS

•  Request Queues & their Processing

- Lab exercises

•  Adding a Driver to the Kernel Tree

•  A sample device driver project