📄 Updated README.md

# Linux Proc File Driver

This project demonstrates a **Linux kernel module** that creates a **proc file** (`/proc/Pyjama_driver`).  
The module supports **read/write** operations, allowing a user-space application (`user-app.py`) to communicate with the kernel.

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## 🚀 Features
- **Proc file interaction** (`/proc/Pyjama_driver`).
- **Read/Write support** from user space.
- **Kernel message logging** (`dmesg`).
- **Multipass VM** for testing.
- **Python user-space applications** for interacting with the kernel.

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## 🛠 Setup & Installation

### **1️⃣ Clone the Repository**
```sh
git clone https://github.com/garry00107/linux-proc-driver.git
cd linux-proc-driver

2️⃣ Build the Kernel Module

make

3️⃣ Load the Module (insmod)

sudo insmod ldd.ko

4️⃣ Verify the Module is Loaded (lsmod)

lsmod | grep ldd

This command checks if the module is successfully loaded.

5️⃣ View Kernel Logs (dmesg)

dmesg | tail -10

It shows recent kernel messages, including those from our module.

6️⃣ Clear Kernel Logs (dmesg -c)

sudo dmesg -c

This clears kernel logs, useful for debugging new changes.

7️⃣ Read from the Proc File

Run the basic read application:

python3 user-app.py

** Read & Write to the Proc File Run the advanced read/write application:

python3 user-app-rw.py Read from the driver: The app will display messages stored in the kernel. Write to the driver: The app allows you to send messages to the kernel.

8️⃣ Read & Write to the Proc File

Run the advanced read/write application:

python3 user-app-rw.py

9️⃣ Unload the Module (rmmod)

sudo rmmod ldd

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📂 Project Structure

📂 linux-proc-driver
├── 📄 ldd.c           # Kernel module source code (read & write support)
├── 📄 Makefile        # Compilation instructions
├── 📄 user-app.py     # Basic Python user-space application (read only)
├── 📄 user-app-rw.py  # Advanced Python app (read & write)
└── 📄 README.md       # Project documentation

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📝 Code Explanation

Kernel Module (ldd.c)

• Creates a proc file at /proc/Pyjama_driver.
• Implements read and write operations.
• Uses proc_create() and proc_remove() for file management.
• Logs messages using printk() (visible via dmesg).

Makefile

• Compiles the kernel module using system headers.

User-Space Applications

1️⃣ user-app.py (Read-Only)

• Opens /proc/Pyjama_driver and reads messages from the kernel.

2️⃣ user-app-rw.py (Read/Write)

• Writes messages to the kernel and reads responses.
• Helps test the write functionality of the proc file.

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🔧 Troubleshooting

1️⃣ "insmod: ERROR: could not insert module: Invalid format"

• Ensure you are using the correct kernel version:

  uname -r

• Recompile the module using:

  make clean && make

2️⃣ "Permission denied" when loading the module

• Use sudo when running insmod or rmmod.

3️⃣ "No such file or directory" when accessing /proc/Pyjama_driver

• Ensure the module is loaded:

  lsmod | grep ldd

• If missing, reload the module:

  sudo insmod ldd.ko

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🙌 Acknowledgments

• Developed as part of a Linux Device Drivers course.
• Tested using Multipass for virtualization.

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>>>>>>> 289b387 (Updated README, modified ldd.c, and added user-app-rw.py)

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