MinimalOS

A minimal operating system with a basic file system and shell interface.

Features

• Bootable from USB drive
• Simple in-memory file system
• Basic shell with commands:
  • ls - List directory contents
  • cd - Change directory
  • mkdir - Create directory
  • pwd - Print working directory
  • clear - Clear screen
  • help - Show available commands
  • uptime - Show system uptime
  • echo - Display text

Building the OS

Prerequisites

You need a cross-compiler for i386-elf target. Follow these steps to set it up:

1. Install build dependencies: ``` sudo apt-get install build-essential bison flex libgmp3-dev libmpc-dev libmpfr-dev texinfo libisl-dev ```

2. Build the cross-compiler (this may take some time): ``` git clone https://github.com/cfenollosa/os-tutorial.git cd os-tutorial/toolchain ./build.sh ```

3. Add the cross-compiler to your PATH: ``` export PATH=$PATH:$HOME/opt/cross/bin ```

Building MinimalOS

1. Clone the repository: ``` git clone https://github.com/yourusername/MinimalOS.git cd MinimalOS ```

2. Build the OS: ``` make ```

3. Create a bootable USB image: ``` make usb ```

4. Write the image to a USB drive (replace /dev/sdX with your USB device): ``` sudo dd if=minimalos.img of=/dev/sdX bs=4M status=progress ```

Testing in QEMU

You can test the OS in QEMU without creating a USB drive:

``` make run ```

Project Structure

• boot/ - Bootloader code
• cpu/ - CPU-specific code (GDT, IDT, etc.)
• drivers/ - Hardware drivers (keyboard, screen, etc.)
• fs/ - File system implementation
• include/ - Header files
• kernel/ - Kernel code
• libc/ - C library functions
• shell/ - Shell implementation

University Project Evaluation Guide

Demonstration Steps

1. Boot the OS from USB:

   • Insert the USB drive into the computer
   • Restart the computer and enter the boot menu (usually F12, F2, or ESC)
   • Select the USB drive to boot from

2. Once booted, you'll see the MinimalOS shell prompt: ``` MinimalOS Shell v1.0 Type 'help' for a list of commands

   minimalos> ```

3. Demonstrate file system commands: ``` minimalos> mkdir test Directory created: test

   minimalos> ls Contents of /: [DIR] test

   minimalos> cd test

   minimalos> pwd /test

   minimalos> mkdir subdir Directory created: subdir

   minimalos> ls Contents of /test: [DIR] subdir

   minimalos> cd ..

   minimalos> pwd / ```

4. Show other commands: ``` minimalos> uptime System uptime: 42 seconds

   minimalos> echo Hello, MinimalOS! Hello, MinimalOS!

   minimalos> clear ```

Key Points to Highlight

1. Bootloader: Explain how the bootloader loads the kernel into memory and switches to 32-bit protected mode.

2. File System: Describe the in-memory file system implementation that supports basic directory operations.

3. Shell Interface: Show how the shell processes commands and interacts with the file system.

4. Device Drivers: Mention the keyboard and screen drivers that enable user interaction.

5. Memory Management: Discuss the memory management utilities and how they're used in the OS.

License

This project is licensed under the GNU General Public License v3.0 - see the LICENSE file for details.