How to Read Until /n With Read() Linux System Call

Adding A Arrangement Phone call To The Linux Kernel (5.viii.1) In Ubuntu (20.04 LTS)

In this guide, you volition learn how to add together a simple system call to the Linux kernel. Check the help sections on the table of contents if you lot need help with text editors.

Department 1 - Preparation
Section 2 - Creation
Department 3 - Installation
Department 4 - Issue
Assistance - Text Editors
Assist - nano

Department 1 - Preparation

In this section, yous will download all necessary tools to add a basic system call to the Linux kernel and run it. This is the only role of the entire process where network connectivity is necessary.

1.1 - Fully update your operating system.

                          sudo              apt update              &&              sudo              apt upgrade              -y                      

i.2 - Download and install the essential packages to compile kernels.

                          sudo              apt              install              build-essential libncurses-dev libssl-dev libelf-dev bison flex              -y                      

If would rather use vim or any other text editor instead of nano, below is an example of how y'all install information technology.

one.3 - Clean up your installed packages.

                          sudo              apt clean              &&              sudo              apt autoremove              -y                      

1.iv - Download the source lawmaking of the latest stable version of the Linux kernel (which is 5.8.1 every bit of 12 August 2020) to your home binder.

            wget              -P              ~/ https://cdn.kernel.org/pub/linux/kernel/v5.ten/linux-v.8.i.tar.xz                      

If you have downloaded a newer version of the Linux kernel, refer to this documentation to acquire nearly any relevant change made to organisation calls.

1.5 - Unpack the tarball you just downloaded to your home binder.

                          tar              -xvf              ~/linux-v.eight.one.tar.xz              -C              ~/                      

1.6 - Reboot your estimator.

Section 2 - Creation

In this department, you lot will write a basic system call in C and integrate it into the new kernel.

2.1 - Cheque the version of your current kernel.

Equally of 12 August 2020, it should brandish the following.

5.4.0-42-generic

In section four, information technology should exist different.

2.2 - Change your working directory to the root directory of the recently unpacked source code.

2.3 - Create the dwelling house directory of your system phone call.

Decide a name for your organization call, and keep it consistent from this point onwards. I have chosen identity.

two.4 - Create a C file for your organisation call.

Create the C file with the following command.

Write the post-obit lawmaking in it.

                          #include <linux/kernel.h> #include <linux/syscalls.h>                            SYSCALL_DEFINE0              (              identity              )              {              printk              (              "I am Jihan Jasper Al-rashid.              \n              "              );              render              0              ;              }                      

You tin can write anything you lot similar hither.

Relieve it and exit the text editor.

2.v - Create a Makefile for your system call.

Create the Makefile with the following command.

Write the following lawmaking in it.

Save information technology and exit the text editor.

2.6 - Add the home directory of your system call to the master Makefile of the kernel.

Open the Makefile with the post-obit control.

Search for core-y. In the second issue, you will run across a series of directories.

kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/

In the fresh source code of Linux five.viii.1 kernel, information technology should be in line 1073.

Add the home directory of your system phone call at the end similar the following.

            kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ block/ identity/                      

Save it and exit the editor.

2.7 - Add a corresponding function image for your system phone call to the header file of system calls.

Open the header file with the following command.

            nano include/linux/syscalls.h                      

Navigate to the bottom of it and write the following code simply higher up

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