Nirmala Venkat at 11:20, 8 July 2020

2020-07-08T11:20:40Z

Nancyvarkey at 17:16, 1 April 2020

2020-04-01T17:16:37Z

Nirmala Venkat at 10:25, 17 March 2020

2020-03-17T10:25:15Z

Nancyvarkey at 13:59, 16 March 2020

2020-03-16T13:59:15Z

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Nirmala Venkat: Created page with " {| style="border-spacing:0;" | style="border:1pt solid #000000;padding:0.176cm;"| Visual cue | style="border:1pt solid #000000;padding:0.176cm;"| Narration |- | style="bord..."

2020-03-13T11:53:53Z

Created page with " {| style="border-spacing:0;" | style="border:1pt solid #000000;padding:0.176cm;"| Visual cue | style="border:1pt solid #000000;padding:0.176cm;"| Narration |- | style="bord..."

New page

{| style="border-spacing:0;"
| style="border:1pt solid #000000;padding:0.176cm;"| Visual cue
| style="border:1pt solid #000000;padding:0.176cm;"| Narration

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 1:

Welcome slide:
| style="border:1pt solid #000000;padding:0.176cm;"| Welcome to the spoken tutorial on '''Loading and Unloading a Module.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 2:

Learning objectives:
* '''insmod '''tool to load a '''module'''.
* '''rmmod '''tool to unload a '''module.'''
* '''dmesg''' command.
* '''depmod, modprobe, objdump''' tools.

| style="border:1pt solid #000000;padding:0.176cm;"| In this tutorial, we will learn how to use,

* '''insmod '''tool to load a '''module'''.
* '''rmmod '''tool to unload a '''module.'''
* '''dmesg''' command.
* '''depmod, modprobe, objdump''' tools.
|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 3:

System Requirements:

* '''VirtualBox 5.2'''
* '''Ubuntu Linux 18.04 LTS''' operating system.
* '''Linux kernel '''version''' 5.0.0-31 generic.'''
* '''gedit text editor.'''

| style="border:1pt solid #000000;padding:0.176cm;"| To record this tutorial, I am using,
* '''VirtualBox 5.2'''
* '''Ubuntu Linux 18.04 LTS''' operating system.
* '''Linux kernel '''version''' 5.0.0-31 generic'''
* '''gedit text editor.'''
|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 4:

Prerequisites:
| style="border:1pt solid #000000;padding:0.176cm;"| To follow this tutorial, you should be familiar with:

* '''C programming language '''and
* Basics of''' Linux kernel'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Open the '''terminal'''

Type >> '''cd DeviceDriver'''
| style="border:1pt solid #000000;padding:0.176cm;"| Open the '''terminal''' by pressing '''ALT+Ctrl+T '''keys simultaneously.

Press the '''Enter''' key after every command.

Go to the folder where '''simple_module dot c''' is saved.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''make all'''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Remember, we have used '''make clean''' command earlier.

To compile the''' module '''again, type '''make all'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''sudo su '''

Press '''Enter'''

Enter the''' password '''

| style="border:1pt solid #000000;padding:0.176cm;"| Type '''sudo space su '''

Enter the '''password''' of the system.

|-
| style="border:1pt solid #000000;padding:0.176cm;"|
| style="border:1pt solid #000000;padding:0.176cm;"| Let us now load the module '''simple_module dot c'''. in the '''kernel''' using '''insmod tool.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''>> insmod simple_module.ko'''

Highlight '''insmod'''
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''insmod space simple_module dot ko.'''

The''' insmod '''tool''' '''loads a''' module '''into the '''kernel.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >>''' clear'''
| style="border:1pt solid #000000;padding:0.176cm;"| Clear the screen

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''lsmod | head -5'''

Press''' Enter'''

Highlight '''lsmod '''

| style="border:1pt solid #000000;padding:0.176cm;"| Let us check whether a '''module''' is loaded into the''' kernel '''or not.

Type''' lsmod space pipe space head space hyphen 5.'''

We know, '''lsmod '''command shows the list of '''modules '''loaded in the current '''kernel.'''

So this '''command '''displays the first five '''modules''' of the list.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''man pipe '''

Press '''Enter'''

Press''' q '''
| style="border:1pt solid #000000;padding:0.176cm;"| To know more about''' linux '''command go through the '''man page '''as shown.

Type '''man space pipe '''

Here, you get more information about''' pipe command. '''

Likewise, explore the command '''head '''to know more.

Press ‘'''q'''’ to exit.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Show the '''output'''

Highlight '''simple_module'''

Highlight '''16384'''
| style="border:1pt solid #000000;padding:0.176cm;"| Here, you can see the name of the '''module''' in this list.

It shows memory utilised by this '''module'''.

It indicates that the '''module '''is loaded into the '''kernel '''successfully.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''clear'''

| style="border:1pt solid #000000;padding:0.176cm;"| Clear the '''screen'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''dmesg | grep my_module '''

Press '''Enter'''

Highlight '''dmesg'''

Highlight '''grep my_module'''

Highlight '''dmesg | grep my_module '''
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''dmesg space pipe space grep space my_module.'''

It displays messages from '''kernel log buffer.'''

The''' grep''' command is used to search for lines matching a specified pattern.

It displays the messages containing the string '''my_module''' in''' '''the''' simple_module.c'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Highlight '''my_module :''' '''inside the init function of our module '''

| style="border:1pt solid #000000;padding:0.176cm;"| Here, '''dmesg '''prints the message from '''init function '''of a '''module.'''

As a '''module''' is loaded into the '''kernel''', only '''init function '''is executed.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''clear'''

| style="border:1pt solid #000000;padding:0.176cm;"| Clear the '''screen'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"|
| style="border:1pt solid #000000;padding:0.176cm;"| Now let us see how to unload a '''module '''from the '''kernel.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type''' rmmod simple_module.ko'''

Press '''Enter'''

Highlight '''rmmod '''
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''rmmod space simple_module dot ko'''.

This tool''' '''unloads a '''module '''from the '''kernel'''.

Let us check this.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''lsmod | head -5 '''and press '''Enter'''

Show the output
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''lsmod space pipe space head space hyphen 5.'''

Now, you can see the '''module '''name is disappeared from this list.

It indicates that the''' module''' is unloaded from the '''kernel '''successfully.
|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >>''' clear'''

| style="border:1pt solid #000000;padding:0.176cm;"| Clear the '''screen.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''dmesg | grep my_module'''

Press '''Enter.'''

Show the output

Highlight''' Inside the exit function of our module '''
| style="border:1pt solid #000000;padding:0.176cm;"| Let us see the '''printk '''messages of a '''module'''.

Type '''dmesg space pipe space grep space my_ module '''

Now, you can see the messages from '''exit function '''also'''.'''

As a '''module''' is unloaded from the '''kernel''', '''exit function '''is executed.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''clear'''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Clear the '''screen'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"|
| style="border:1pt solid #000000;padding:0.176cm;"| Let us see the use of the '''depmod command.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''man 8 depmod'''

Press''' Enter'''

| style="border:1pt solid #000000;padding:0.176cm;"| Type '''man space 8 space depmod'''.

It creates a dependency file named '''modules''.''dep.'' '''''

This '''dependency file''' is later used by '''modprobe''' '''tool.'''

You can get more information about '''depmod''' from it’s '''manpage.'''

Press ‘'''q'''’ to exit.

|-
| style="border:1pt solid #000000;padding:0.176cm;"|
| style="border:1pt solid #000000;padding:0.176cm;"| Let us see the use of the '''modprobe''' tool.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''man''' '''8''' '''modprobe '''

Press''' Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''man''' '''space 8 space modprobe.'''

The''' modprobe''' tool intelligently adds or removes a '''module''' from the''' kernel.'''

Some '''modules '''depend on other '''modules'''.

This '''tool '''automatically loads and unloads its dependent '''modules.'''

You can get more information about '''modprobe''' tool from it’s '''manpage'''

The '''modprobe''' expects an up-to-date '''modules dot dep file '''generated''' '''by''' '''the''' depmod.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Press q
| style="border:1pt solid #000000;padding:0.176cm;"| Press ‘'''q'''’ to exit.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''clear'''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Clear the '''screen'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''insmod simple_module.ko'''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Let us now load a '''module''' in the '''kernel '''again.

Type '''insmod space simple_module dot ko '''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''lsmod | head -5'''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Let us check a '''module''' is loaded into the '''kernel''' or not.

Type '''lsmod space pipe space head space hyphen 5 '''

As a '''module''' loaded into the '''kernel''' successfully, it appears here.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''clear'''

Press '''Enter'''.
| style="border:1pt solid #000000;padding:0.176cm;"| Clear the screen.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''readelf hyphen h simple_module.ko'''

Press '''Enter'''.

Highlight '''.ko'''

Highlight''' ELF Header.'''
| style="border:1pt solid #000000;padding:0.176cm;"| Let us see the '''ELF''' '''file''' of the '''module'''.

Type '''readelf space hyphen h space simple_module dot ko '''

Here''', '''the''' dot ko''' is an '''ELF''' '''file'''.

Each''' ELF file''' is made up of one '''ELF header''', followed by '''file''' data.

The''' elf header''' describes the overall information of the '''module dot ko file.'''

'''ELF''' means “'''Executable and Linking Format'''”.

It is a standard '''executable file format '''in '''Linux'''.

Clear the screen.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''objdump -f simple_module.ko'''

Press '''Enter'''

Highlight '''-f'''

Highlight '''simple_module.ko'''

Highlight '''elf64-x86-64'''

Highlight '''i386:x86-64'''

Highlight '''start address'''
| style="border:1pt solid #000000;padding:0.176cm;"| Let us see the information about the '''object file.'''

Type '''objdump space hyphen f space simple_module dot ko.'''

The''' hyphen f '''option shows our '''module’s elf header'''.

It shows the name of a '''module, '''the '''file '''format of a '''module file'''.

It shows the '''architecture''' of our system, and the entry point '''function’s address.'''

For more information, go through it’s '''manpage.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''clear '''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Clear the '''screen.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''rmmod simple_module'''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| To unload the''' module''' from the '''kernel''', type '''rmmod simple_module.ko'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''make clean'''

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| Type '''make clean.'''

So all extra '''files '''will be removed from the '''present working directory. '''
|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type >> '''exit'''

Press '''Enter'''

Type >> exit

Press '''Enter'''
| style="border:1pt solid #000000;padding:0.176cm;"| To go back to '''regular user''', type '''exit'''

To go back to '''user login, t'''ype''' exit''' '''.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 5:

Summary:
| style="border:1pt solid #000000;padding:0.176cm;"| In this tutorial, we learnt how to use

* '''insmod '''tool to load a '''module'''.
* '''rmmod '''tool to unload a '''module.'''
* '''dmesg''' command.
* '''depmod, modprobe, objdump''' tools.
|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 6:

Assignment:
| style="border:1pt solid #000000;padding:0.176cm;"| As an assignment,

# Open the '''simple_module.c '''file.
# Change the message in '''printk''' function of '''init_function.'''
# Load the module using '''insmod''' tool.
# See the output of '''dmesg''' command.
# Remove the module using''' rmmod''' tool

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 7:

About Spoken Tutorial Project:
| style="border:1pt solid #000000;padding:0.176cm;"| * The video at the following link summarizes the Spoken Tutorial project.

* Please download and watch it.
|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 8:

Spoken Tutorial workshops:
| style="border:1pt solid #000000;padding:0.176cm;"| The''' Spoken Tutorial Project''' Team:

* conducts workshops and
* gives certificates.

For more details, please write to us.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 9:

Forum questions:
| style="border:1pt solid #000000;padding:0.176cm;"| Please post your timed queries in this forum.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 10:

Forum for specific questions:
| style="border:1pt solid #000000;padding:0.176cm;"| * Do you have any general or technical questions on Embedded Linux Device Driver?
* Please visit the FOSSEE forum and post your question.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 11

Acknowledgment:
| style="border:1pt solid #000000;padding:0.176cm;"| Spoken Tutorial project is funded by MHRD, Government of India.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 12:

Thank you slide:
| style="border:1pt solid #000000;padding:0.176cm;"| This tutorial has been contributed by FOSSEE and Spoken Tutorial Project, IIT Bombay.

This is Mayuri Panchakshari signing off.

Thanks for watching.

|}

@@ Line 379: / Line 379: @@
 | style="border:1pt solid #000000;padding:0.176cm;"| To go back to '''regular user''', type '''exit'''
-To go back to '''user login, type''' exit'''.
+To go back to '''user login''', type '''exit'''.
 |-

@@ Line 48: / Line 48: @@
 * '''C programming language '''and
 * Basics of''' Linux kernel'''
+If not, then go through the '''C/C++''' and '''Linux''' spoken tutorials on this website
 |-
 | style="border:1pt solid #000000;padding:0.176cm;"| Open the '''terminal'''
@@ Line 380: / Line 380: @@
 To go back to '''user login''', type '''exit'''.
 |-

@@ Line 197: / Line 197: @@
 | style="border:1pt solid #000000;padding:0.176cm;"| Type '''lsmod space pipe space head space hyphen 5.'''
-Now, you can see the '''module '''name is disappeared from this list.
+Now, you can see the '''module '''name has disappeared from this list.
 It indicates that the''' module''' is unloaded from the '''kernel '''successfully.

Embedded-Linux-Device-Driver/C2/Loading-and-Unloading-a-Module/English - Revision history

Nirmala Venkat at 11:20, 8 July 2020

Nancyvarkey at 17:16, 1 April 2020

Nirmala Venkat at 10:25, 17 March 2020

Nancyvarkey at 13:59, 16 March 2020

Nirmala Venkat: Created page with " {| style="border-spacing:0;" | style="border:1pt solid #000000;padding:0.176cm;"| Visual cue | style="border:1pt solid #000000;padding:0.176cm;"| Narration |- | style="bord..."