# First LKM (Loadable Kernel Module)

This repository contains a simple example of a Loadable Kernel Module (LKM) for Linux, demonstrating basic interactions with the `/proc` filesystem through custom read and write handlers. It is designed for learning and experimenting with Linux kernel programming concepts.

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## Features

- **Custom `/proc` entry**: Creates a `/proc/driver_name` node.
- **Read functionality**: Returns the contents of a kernel buffer or a default message ("Acknowledge\n") when read.
- **Write functionality**: Updates the kernel buffer with data from user space.
- **Kernel logging**: Logs actions to the kernel message buffer using `printk`.

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## Files

- **Source Code**: `ldd.c`
  - Implements the LKM, including initialization, cleanup, and `/proc` entry operations.

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## Installation

### Prerequisites

- A Linux system with kernel development tools installed.
- Kernel headers for the currently running kernel.

### Steps

1. **Clone the Repository**:
   ```bash
   git clone <repository_url>
   cd <repository_directory>

2. Build the Module:

   make

3. Insert the Module:

   sudo insmod driver_name.ko

4. Verify Installation: Check the kernel message log for initialization messages:

   dmesg | tail -n 20

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Usage

Read Data from /proc/driver_name:

cat /proc/driver_name

Write Data to /proc/driver_name:

echo "Your message" > /proc/driver_name

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Cleanup

1. Remove the Module:

   sudo rmmod driver_name

2. Verify Removal: Check the kernel message log for cleanup messages:

   dmesg | tail -n 20

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Development Notes

Kernel Logs

Use dmesg to view logs generated by printk statements in the module.

Permissions

The /proc/driver_name node is created with 0666 permissions, allowing both read and write access to all users.

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License

This module is licensed under the GNU General Public License (GPL). See the LICENSE file for details.

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Author

Developed by Krishnaprasad Sreekumar Nair.