Initial commit, working

README.md

@@ -0,0 +1,161 @@
+# Simple UEFI Operating System
+
+A minimal bootable UEFI operating system written in C that demonstrates basic UEFI functionality.
+
+## Features
+
+- **UEFI Boot**: Boots directly on UEFI firmware
+- **Console I/O**: Interactive keyboard input and screen output
+- **System Information**: Displays firmware details
+- **Simple Commands**: Interactive command interface
+
+## Requirements
+
+- GCC compiler
+- GNU-EFI library
+- QEMU with OVMF firmware
+- Make
+
+## Installation
+
+### On Debian/Ubuntu:
+
+```bash
+make install-deps
+```
+
+Or manually:
+
+```bash
+sudo apt-get install gnu-efi qemu-system-x86 ovmf gcc binutils make
+```
+
+### On Arch Linux:
+
+```bash
+sudo pacman -S gnu-efi qemu-system-x86 edk2-ovmf gcc binutils make
+```
+
+### On Fedora/RHEL:
+
+```bash
+sudo dnf install gnu-efi qemu-system-x86 edk2-ovmf gcc binutils make
+```
+
+## Building
+
+Build the UEFI application:
+
+```bash
+make
+```
+
+This will create `build/EFI/BOOT/BOOTX64.EFI`
+
+## Running
+
+Test with QEMU (no graphics mode):
+
+```bash
+make run
+```
+
+### QEMU Controls:
+- **Exit QEMU**: Press `Ctrl+A`, then `X`
+- **Shutdown OS**: Press `q` in the OS
+
+## Commands in the OS
+
+Once the OS boots, you can use these commands:
+
+- `h` - Display help
+- `i` - Display system information
+- `c` - Clear screen
+- `q` - Shutdown the system
+
+## Project Structure
+
+```
+.
+├── main.c          # Main UEFI application source code
+├── Makefile        # Build configuration
+└── README.md       # This file
+```
+
+## How It Works
+
+1. **UEFI Entry Point**: The `efi_main` function is the entry point called by UEFI firmware
+2. **Initialization**: GNU-EFI library is initialized with the system table
+3. **Console Setup**: Output is configured and screen is cleared
+4. **Main Loop**: The OS enters a loop waiting for keyboard input
+5. **Command Processing**: User commands are processed and executed
+6. **Shutdown**: UEFI runtime services are used to shutdown the system
+
+## Building for Real Hardware
+
+To create a bootable USB drive:
+
+1. Build the project: `make`
+2. Format a USB drive with GPT and create an EFI partition (FAT32)
+3. Mount the EFI partition
+4. Copy `build/EFI/BOOT/BOOTX64.EFI` to `/EFI/BOOT/` on the USB drive
+5. Boot from the USB drive in UEFI mode
+
+**Warning**: Always backup your data before creating bootable media!
+
+## Cleaning
+
+Remove build artifacts:
+
+```bash
+make clean
+```
+
+## Troubleshooting
+
+### GNU-EFI headers not found
+
+Make sure GNU-EFI is installed. The headers are typically in `/usr/include/efi`.
+
+If installed in a different location, update the `EFI_INC` variable in the Makefile.
+
+### OVMF firmware not found
+
+OVMF files might be in different locations depending on your distribution:
+- `/usr/share/OVMF/`
+- `/usr/share/qemu/`
+- `/usr/share/edk2-ovmf/`
+
+Update the paths in the Makefile if needed.
+
+### QEMU crashes or fails to start
+
+Ensure you have QEMU with x86_64 support and OVMF firmware installed.
+
+## Technical Details
+
+- **Architecture**: x86_64
+- **Firmware Interface**: UEFI 2.x
+- **Development Library**: GNU-EFI
+- **Executable Format**: PE32+ (Portable Executable for EFI)
+- **Boot Protocol**: UEFI Boot Services
+
+## License
+
+This is a minimal educational example. Feel free to use and modify as needed.
+
+## Further Development
+
+Ideas for expansion:
+- File system support
+- Memory management
+- Graphics output
+- Network stack
+- Device drivers
+- Multi-tasking
+
+## Resources
+
+- [UEFI Specification](https://uefi.org/specifications)
+- [GNU-EFI Documentation](https://sourceforge.net/projects/gnu-efi/)
+- [OSDev Wiki](https://wiki.osdev.org/)