Character Device Drivers in deep

Name: Character Device Drivers in deep
Rating: 4.3 (151 reviews)

Linux Kernel Programming - Character Device Drivers

Created byLinux Trainer

Last updated 10/2020

English

What you'll learn

Write character device driver from scratch
Understand the various file operations provided by character driver

Course content

6 sections • 88 lectures • 4h 20m total length

Introduction to character device drivers3:36
List Character and Block Devices2:28
Steps in Registering a character driver0:41
Device Number = Major + Minor3:32
How to choose a device number1:58
Data type for device number dev_t0:50
Example of MAJOR,MINOR,MKDEV macros3:27
/proc/devices file1:03
Static Allocation of Device Numbers1:36
Example of static allocation of device numbers2:26
Test cases on Previous Example1:58
What happens if i try to register same major number1:39
What happens if i try to register same name1:36
Registering Maximum Minor Numbers3:27
What is Maximum Major Number3:02
Dynamic Allocation of Device Number0:48
Example of dynamic allocation of device number1:54
Calling alloc_chrdev_region in loop4:12
Manual Device Node Creation3:54
Automatic Device Node Creation - class_create4:02
Automatic Device Node Creation - device_create2:48
Example of automatic device node creation1:54
Quiz 1

Introduction1:46
Registering file_operations with Linux Kernel1:44
cdev_init vs cdev_alloc1:27
Linux Kernel Module example of file operations registrations - cdev_alloc3:14
Linux Kernel Module example of file operations registrations - cdev_init2:33
Pseudo Devices - /dev/null, /dev/zero, /dev/urandom4:25
Walkthrough of drivers/char/mem.c2:42
How many times open and release will be called in case of fork4:16
How many times open and release will be called in case of multiple processes1:27
struct file3:14
Example of struct file2:27
struct inode3:12
Example of struct inode2:33
Example of struct inode vs struct file3:28
What happens when i print user space buffer in write function5:27
Accessing user space buffer in Kernel space2:26
copy_from_user2:58
What happens when i pass NULL ptr in write system call1:19
copy_to_user1:41
put_user4:11
get_user2:14
Passing structure from user space to kernel space and vice versa2:47
Can i pass user variables on heap to kernel driver1:52
Passing structure with one member from stack and other in heap2:29
Kernel utility to print dev_t - print_dev_t, format_dev_t3:53
Can i use strlen in kernel space4:14
strnlen_user2:30
Solution to passing structure with one member in stack and other in heap3:16
Problem in character driver when we read character by character2:33
Adding offset support in read and write implementation5:44
Updated logic to read/write bytes less than requested/available3:51
Adding lseek support2:17
Creating multiple device nodes3:52
container_of macro3:32
Adding support for private data2:25
What happens when i call write from user space4:26

Introduction3:54
Ioctl example - BLKGETSIZE3:13
Ioctl example - BLKGETSIZE641:16
Ioctl driver method - unlocked_ioctl3:26
Adding three ioctls in kernel driver3:24
Symbolic names to ioctls commands1:58
Defining ioctl commands6:07
C Example of ioctl macros1:52
Macros to decode information from ioctl command1:59
Updated driver code using ioctl macros1:59
What should be the return value if unsupported command is sent from user space1:34
access_ok macro2:25
Updated driver code using access_ok macro2:32
Fail scenarios of access_ok2:23
What happens when we pass a different size in ioctl command2:41
compat_ioctl6:05
Issues when 32-bit process trying to perform ioctl command6:21
Sending a signal from module to process3:39

How many times a device driver is being used by application2:34
Allow only one process to use the device file at a time4:59
Restricting access to a single user at a time5:59
Capabilities5:19
Example of using capabilities - cap_dac_override3:15
Example of using capabilities - cap_sys_module3:14
Example of using capabilities - cap_sys_admin2:55
Open Flags5:11
What happens if I don't call close and process terminates1:47

Requirements

Should be able to write/compile/load/unload Hello World Linux Kernel Modules

Description

Updated on Oct 10: Added Downloads section

What will you learn from this course?

Introduction to character drivers
What is device number and device file
Allocating device number - statically and dynamically
Creating device file - Manually(mknod) and automatically (udev)
Registering character device and its file operation with Kernel
Copying data from user space to kernel space and vice versa
Understanding the various structures - struct file and struct inode
Implementation of open, release, read, write, llseek, ioctl file operations
How to create multiple device nodes and add support for private data
Flow of write system call from kernel system call entry point to driver write file operations
Handling all the error cases in ioctl implementation
Sending a signal to user space from kernel space
Various access control mechanisms and capabilities
Misc Driver

API's covered in this course:

MAJOR
MINOR
MKDEV
register_chrdev_region
alloc_chrdev_region
class_create
device_create
class_destroy
device_destroy
unregister_chrdev_region
imajor
iminor
copy_from_user
copy_to_user
put_user
get_user
print_dev_t
format_dev_t
strnlen_user
container_of
access_ok

Commands used in this course:

mknod
udevadm monitor

Who this course is for:

Developers interested in learning Linux Kernel Programming

Character Device Drivers in deep

What you'll learn

Explore related topics

Course content

Introduction22 lectures • 53min

File Operations36 lectures • 1hr 48min

IOCTL18 lectures • 57min

Access Control and Capabilities9 lectures • 35min

Misc Driver2 lectures • 7min

Resources1 lecture • 1min

Requirements

Description

Who this course is for: