Developing Embedded Linux Device Drivers (LFD435)
Develop device drivers for embedded Linux systems—gain essential knowledge of the Linux kernel through hands-on labs with RISC-V-based emulated development targets.
Description
Develop device drivers for embedded Linux systems—gain essential knowledge of the Linux kernel through hands-on labs with RISC-V-based emulated development targets. This course empowers experienced programmers to build and refine device drivers with practical, real-world experience
Summary
Develop device drivers for embedded Linux systems—gain essential knowledge of the Linux kernel through hands-on labs with RISC-V-based emulated development targets.
What You'll Learn
- Upon mastering this material, you will be familiar with the different kinds of device drivers used under Linux, and have an introduction to many of the appropriate APIs to be used when writing a device driver.
- The labs for illustrating these concepts will all be performed on ARM hardware in order to get developers familiar with cross-compiling and developing drivers for an embedded target.
Prerequisites
- Knowledge of basic kernel interfaces and methods such as how to write, compile, load and unload modules, use synchronization primitives, and the basics of memory allocation and management, such as is provided by LFD420 (Kernel Internals and Development).
- Pre-class preparation material will be provided before class
Outline
38 modules
•
4 Days total
- Objectives
- Who You Are
- The Linux Foundation
- Copyright and No Confidential Information
- Linux Foundation Training
- Certification Programs and Digital Badging
- Linux Distributions
- Preparing Your System
- Things change in Linux
- Documentation and Links
- Procedures
- Kernel Versions
- Kernel Sources and Use of git
- Hardware
- Staging Tree
- Labs
- Overview on How to Contribute Properly
- Know Where the Code is Coming From: DCO and CLA
- Stay Close to Mainline for Security and Quality
- Study and Understand the Project DNA
- Figure Out What Itch You Want to Scratch
- Identify Maintainers and Their Work Flows and Methods
- Get Early Input and Work in the Open
- Contribute Incremental Bits, Not Large Code Dumps
- Leave Your Ego at the Door: Don't Be Thin-Skinned
- Be Patient, Develop Long Term Relationships, Be Helpful
- The Compiler Triplet
- Built-in Linux Distribution Cross Compiler
- Linaro
- CodeSourcery
- crosstool-ng
- Buildroot
- OpenEmbedded
- Yocto Project
- Labs
- What is QEMU?
- Why use QEMU?
- Emulated Architectures
- Image Formats
- Labs
- Why do we use uSD cards?
- Getting SW onto a uSD card
- Booting from flash
- Why is using uSD cards a bad idea?
- Labs
- Using virtual Hardware
- An easier way to develop
- The Boot Sequence using TFTP and NFSroot
- Objectives of the Lab
- Labs
- Configuring the Kernel for the Development Board
- Labs
- Types of Devices
- Mechanism vs. Policy
- Avoiding Binary Blobs
- Power Management
- How Applications Use Device Drivers
- Walking Through a System Call Accessing a Device
- Error Numbers
- printk()
- devres: Managed Device Resources
- Labs
- The module_driver() Macros
- Modules and Hot Plug
- Labs
- Virtual and Physical Memory
- Memory Zones
- Page Tables
- kmalloc()
- __get_free_pages()
- vmalloc()
- Slabs and Cache Allocations
- Labs
- Device Nodes
- Major and Minor Numbers
- Reserving Major/Minor Numbers
- Accessing the Device Node
- Registering the Device
- udev
- dev_printk() and Associates
- file_operations Structure
- Driver Entry Points
- The file and inode Structures
- Miscellaneous Character Drivers
- Labs
- Components of the Kernel
- User-Space vs. Kernel-Space
- What are System Calls?
- Available System Calls
- Scheduling Algorithms and Task Structures
- Process Context
- Labs
- Transferring Between Spaces
- put(get) user() and copy_to(from)_user()
- Direct Transfer: Kernel I/O and Memory Mapping
- Kernel I/O
- Mapping User Pages
- Memory Mapping
- User-Space Functions for mmap()
- Driver Entry Point for mmap()
- Accessing Files from the Kernel
- Labs
- What are Platform Drivers?
- Main Data Structures
- Registering Platform Devices
- An Example
- Hardcoded Platform Data
- The New Way: Device Trees
- Labs
- What are Device Trees?
- What Device Trees Do and What They Do Not Do
- Device Tree Syntax
- Device Tree Walk Through
- Device Tree Bindings
- Device Tree support in Boot Loaders
- Using Device Tree Data in Drivers
- Coexistence and Conversion of Old Drivers
- Labs
- What are Interrupts and Exceptions?
- Exceptions
- Asynchronous Interrupts
- MSI
- Enabling/Disabling Interrupts
- What You Cannot Do at Interrupt Time
- IRQ Data Structures
- Installing an Interrupt Handler
- Labs
- Kinds of Timing Measurements
- Jiffies
- Getting the Current Time
- Clock Sources
- Real Time Clock
- Programmable Interval Timer
- Time Stamp Counter
- HPET
- Going Tickless
- Inserting Delays
- What are Kernel Timers?
- Low Resolution Timer Functions
- Low Resolution Timer Implementation
- High Resolution Timers
- Using High Resolution Timers
- Labs
- What are ioctls?
- Driver Entry point for ioctls
- Defining ioctls
- Labs
- Unified Device Model
- Basic Structures
- Real Devices
- sysfs
- kset and kobject examples
- Labs
- What is Firmware?
- Loading Firmware
- Labs
- What are Wait Queues?
- Going to Sleep and Waking Up
- Going to Sleep Details
- Exclusive Sleeping
- Waking Up Details
- Polling
- Labs
- Top and Bottom Halves
- Softirqs
- Tasklets
- Work Queues
- New Work Queue API
- Creating Kernel Threads
- Threaded Interrupt Handlers
- Interrupt Handling in User-Space
- Labs
- Memory Barriers
- Allocating and Mapping I/O Memory
- Accessing I/O Memory
- What is DMA?
- DMA Directly to User
- DMA and Interrupts
- DMA Memory Constraints
- DMA Masks
- DMA API
- DMA Pools
- Scatter/Gather Mappings
- Labs
- What are MTD Devices?
- NAND vs. NOR vs. eMMC
- Driver and User Modules
- Flash Filesystems
- What is USB?
- USB Topology
- Terminology
- Endpoints
- Descriptors
- USB Device Classes
- USB Support in Linux
- Registering USB Device Drivers
- Moving Data
- Example of a USB Driver
- Labs
- Evaluation Survey
- UNIX and Linux
- Monolithic and Micro Kernels
- Object-Oriented Methods
- Main Kernel Components
- User-Space and Kernel-Space
- Task Structure
- Memory Allocation
- Transferring Data between User and Kernel Spaces
- Object-Oriented Inheritance - Sort Of
- Linked Lists
- Jiffies
- Labs
- What are Modules?
- A Trivial Example
- Compiling Modules
- Modules vs Built-in
- Module Utilities
- Automatic Module Loading
- Module Usage Count
- Module Licensing
- Exporting Symbols
- Resolving Symbols
- Labs
- Processes, Threads, and Tasks
- Kernel Preemption
- Real Time Preemption Patch
- Labs
- Installation and Layout of the Kernel Source
- Kernel Browsers
- Kernel Configuration Files
- Kernel Building and Makefiles
- initrd and initramfs
- Labs
- Coding Style
- Using Generic Kernel Routines and Methods
- Making a Kernel Patch
- sparse
- Using likely() and unlikely()
- Writing Portable Code, CPU, 32/64-bit, Endianness
- Writing for SMP
- Writing for High Memory Systems
- Power Management
- Keeping Security in Mind
- Labs
- Concurrency and Synchronization Methods
- Atomic Operations
- Bit Operations
- Spinlocks
- Seqlocks
- Disabling Preemption
- Mutexes
- Semaphores
- Completion Functions
- Read-Copy-Update (RCU)
- Reference Counts
- Labs
- Virtual Memory Management
- Systems With and Without MMU and the TLB
- Memory Addresses
- High and Low Memory
- Memory Zones
- Special Device Nodes
- NUMA
- Paging
- Page Tables
- page structure
- Labs
- Requesting and Releasing Pages
- Buddy System
- Slabs and Cache Allocations
- Memory Pools
- kmalloc()
- vmalloc()
- Early Allocations and bootmem()
- Memory Defragmentation
- Labs