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 Modules

  • get kernel sources
  • configure/build/install
  • device drivers (statically linked, loaded at runtime)
  • init/exit
  • 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 Charachter 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
    • function graph tracer
    • dynamic tracer
  • trace-cmd/kernelshark
  • perf
  • 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
  • threaded interrrupts

Concurrency

  • critical region/section
  • atomic
  • race condition
  • synchronization
  • locking
  • locking solutions
  • deadlock
  • contention
  • what to lock?
  • what can be used?
    • 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

Except where otherwise noted content and this course outline are licensed under Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0).

Requirements

  • 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!) and/or have a good understanding of the topics outlined there
  35 Hours
 

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Dates are subject to availability and take place between 09:30 and 16:30.
Open Training Courses require 5+ participants.

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