Agenda for Training course Embedded GNU/Linux Device Drivers

This 5-day training class uses hands-on exercises combined with instruction to illustrate the concepts of GNU/Linux kernel internals and device driver development. It is designed to bring you quickly up to speed. We describe processes, concepts and commands necessary to write GNU/Linux device drivers through a combination of theory and on-the-job training. Don’t reinvent the wheel, but learn from an experienced trainer and take home a working knowledge and the ability to use it effectively in your own embedded development project.

Prerequisites

• Basic familiarity with using a GNU/Linux system as an end user
• Basic familiarity with a command line shell
• Basic knowledge of user space / application development
• Intermediate C programming knowledge
• Should have attended Embedded GNU/Linux Systems Architecture before (strongly recommended!)

Who should attend?

People with interest in or tasked with the development or evaluation of developing GNU/Linux device drivers like software engineers, field engineers, (project) managers, hardware engineers.

Course Outline

Introduction

• quick history of GNU/Linux
• licensing
• kernel versioning
• release cycle
• kernel trees
• mainline
• kernel vs. user space
• mechanism vs. policy
• kernel driver alternatives
• RTOS vs. Linux

Memory Management

• Virtual memory vs. physical memory
• memory allocation in kernel
• pages
• zones
• API
• slab

Kernel Patch

• life cycle
• git
• kernel source
• create patch
• check patch
• fix patch
• ship patch
• audited code

Kernel Module

• get kernel sources
• configure
• build
• install
• device drivers (statically linked, loaded at runtime)
• init
• licensing
• EXPORT SYMBOL GPL
• out of tree makefile
• module-init-tools
• module in kernel tree
• Kconfig
• parameter passing
• sparse

Char Drivers

• architecture
• user/kernel interface
• I/O subsystem
• VFS
• sysfs (devices, bus, drivers, classes)
• kobject
• ktype
• kset
• linux kernel driver model
• device files
• char driver
  • initialization
  • registration
  • open, release
  • cdev, cdev add, cdev del,...
  • major/minor numbers
  • udev, udevmonitor, udevadm

Advanced Character Driver Operations

• ioctl
• unlocked ioctl
• compat ioctl
• user space API
• kernel space API
• process lifecycle
• sleeping/blocking
• sleeping/waking up
• wait queue
• thundering herd
• poll/select

Kernel Debugging

• bug
• debugging
• debugging the kernel
• binary search with git
• debug support from kernel
• printk
  • syslogd
  • klogd
  • loglevels
  • rate limit
  • debug levels
  • debug selective subsystems
• debugging by querying debugfs
• oops debugging, asserting oops
• Magic SysRq^? Key
• kgdb/kdb
• JTAG

Tracing

• gcov
• lcov
• oprofile
• ftrace
  • nop tracer
  • function tracer
  • sched switch tracer (viewer)
  • function graph tracer
  • dynamic tracer
• LTTng

Interrupts

• interrupts vs. polling
• interrupt
• program sections
• reentrancy
• events
• interrupt handler
• shared interrupt handler
• interrupt flow
• interrupt control

Deferring Work

• top/bottom halves
• softirqs
• tasklets
• work queues

Concurrency

• critical region/section
• atomic
• race condition
• synchronization
• locking
• locking solutions
• deadlock
• contention
• what to lock?
• what to use?
  • atomic operations
  • spin locks
  • reader-writer spin locks
  • semaphore
  • binary semaphore
  • mutex
  • reader-writer semaphore
  • completion variables
  • sequential locks
  • disable preemption
  • orderig and barriers

Time

• HZ
• Jiffies
• big/small delays
• kernel timers

Hardware I/O

• I/O Ports
• I/O Memory
• How to deal with side effects accessing registers?

User-Kernel Communication

• put(get) user()
• copy to(from) user()
• Kernel I/O
• memory mapping
• procfs
• sysfs
• debugfs
• relayfs
• netlink
• ioctl

Portability

• word size
• opaque types
• signed/unsigned char
• data alignment
• integral promotion
• code reuse
• endianess
• system tick
• page size
• instruction ordering
• SMP/preemption/high memory