Programming Embedded Linux

Introduction

• What is Linux
• Layers in a Linux system
• Linux vs. Legacy RTOS
   

Basic concepts

• Files and file system
• The shell
• Basic commands
• Processes
• Setting up networking
   

Application programming and the user space API

• Makefiles and the build environment
• Processes and threads
• Real time priorities
   

Application programming and the user space API

• Synchronization and IPC (mutex, condition variables, mailboxes, pipes, shared memory, Unix domain sockets and signals)
• Timers
• Memory mapping and locking
• Debugging applications: in process and using remote debugger
• Labs – using pipes, debugging
   

Linux Kernel

• Kernel overview
• History
• Versions
• Source code layout
• Good practices
• System call interface
   

Writing a simple kernel module

• A simple kernel module structure
• Implicit steps of compiling modules in Linux kernel version 2.6
• Using shell commands to manipulate modules
• The kernel log
• Using the printk function
• Passing parameters to the module
   

Memory Management

• Memory areas
• Memory page frames
• Requesting and releasing page frames
• Allocating contiguous virtual memory area
• The slab and slob allocators
• Memory caches and allocations
• Managing slabs
• Creating and destroying caches
• User space memory access
   

Implementing a character device file

• The VFS structure
• Initialization and termination
• Opening the device file
• IOCTL
• Implementing base operations
   

Debugging

• Kernel configuration for debugging
• printk
• KGDB
• Oops messages
   

Locking mechanisms

• Locking requirements
• Preemption
• Atomic bit operations
• Interrupt disabling
• Spin lock
• Semaphores
   

Linux Scheduler

• Process and thread
• Scheduling policies
• Priorities
• Kernel tasks
• task_struct structure
• SMP scheduling
   

Interrupt handling

• Hardware interrupt handling basics
• Interrupt handler and control
• Low level handling
• Wait queues technique
• Threaded interrupts
   

 Bottom halves

• Differing work
• Using software interrupts
• Tasklets
• Timers & RTC
• Work queues
   

Network sub system overview

• The layer model
• Registration and un-registration
• Socket buffers, allocations and manipulations
• Network headers
• Packet reception
• Packet transmission
• NAPI