Initial commit, working

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2026-02-26 17:37:57 +00:00
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.gitignore vendored Normal file
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# Build directory
build/
# Object files
*.o
*.so
*.efi
*.EFI
# Editor files
*.swp
*.swo
*~
.vscode/
.idea/
# OS files
.DS_Store
Thumbs.db

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Makefile Normal file
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# Makefile for UEFI Operating System
# Architecture
ARCH = x86_64
# Compiler and tools
CC = gcc
LD = ld
OBJCOPY = objcopy
# Directories
SRC_DIR = .
BUILD_DIR = build
EFI_DIR = $(BUILD_DIR)/EFI/BOOT
IMAGE_DIR = $(BUILD_DIR)/image
# GNU-EFI paths (common locations)
EFI_INC = /usr/include/efi
EFI_INCLUDES = -I$(EFI_INC) -I$(EFI_INC)/$(ARCH) -I$(EFI_INC)/protocol
EFI_LDS = /usr/lib/elf_$(ARCH)_efi.lds
EFI_CRT_OBJS = /usr/lib/crt0-efi-$(ARCH).o
EFI_LIB_PATHS = -L/usr/lib
# Compiler flags
CFLAGS = -ffreestanding -fno-stack-protector -fpic \
-fshort-wchar -mno-red-zone -Wall -Wextra \
$(EFI_INCLUDES) -DEFI_FUNCTION_WRAPPER
# Linker flags
LDFLAGS = -nostdlib -znocombreloc -T $(EFI_LDS) -shared \
-Bsymbolic $(EFI_LIB_PATHS) $(EFI_CRT_OBJS)
# Libraries
LIBS = -lefi -lgnuefi
# Target
TARGET = BOOTX64.EFI
TARGET_SO = bootx64.so
OBJ = $(BUILD_DIR)/main.o
# QEMU settings
QEMU = qemu-system-x86_64
# Try to find OVMF firmware (different locations on different distros)
OVMF_CODE := $(shell \
if [ -f /usr/share/OVMF/OVMF_CODE_4M.fd ]; then \
echo /usr/share/OVMF/OVMF_CODE_4M.fd; \
elif [ -f /usr/share/OVMF/OVMF_CODE.fd ]; then \
echo /usr/share/OVMF/OVMF_CODE.fd; \
elif [ -f /usr/share/qemu/OVMF_CODE.fd ]; then \
echo /usr/share/qemu/OVMF_CODE.fd; \
elif [ -f /usr/share/edk2-ovmf/x64/OVMF_CODE.fd ]; then \
echo /usr/share/edk2-ovmf/x64/OVMF_CODE.fd; \
else \
echo /usr/share/OVMF/OVMF_CODE.fd; \
fi)
OVMF_VARS_TEMPLATE := $(shell \
if [ -f /usr/share/OVMF/OVMF_VARS_4M.fd ]; then \
echo /usr/share/OVMF/OVMF_VARS_4M.fd; \
elif [ -f /usr/share/OVMF/OVMF_VARS.fd ]; then \
echo /usr/share/OVMF/OVMF_VARS.fd; \
elif [ -f /usr/share/qemu/OVMF_VARS.fd ]; then \
echo /usr/share/qemu/OVMF_VARS.fd; \
elif [ -f /usr/share/edk2-ovmf/x64/OVMF_VARS.fd ]; then \
echo /usr/share/edk2-ovmf/x64/OVMF_VARS.fd; \
else \
echo /usr/share/OVMF/OVMF_VARS.fd; \
fi)
QEMU_FLAGS = -machine q35 \
-drive if=pflash,format=raw,readonly=on,file=$(OVMF_CODE) \
-drive if=pflash,format=raw,file=$(BUILD_DIR)/OVMF_VARS.fd \
-drive format=raw,file=fat:rw:$(BUILD_DIR) \
-net none \
-nographic
# Phony targets
.PHONY: all clean run setup install-deps
# Default target
all: setup $(EFI_DIR)/$(TARGET)
# Create necessary directories
setup:
@mkdir -p $(BUILD_DIR)
@mkdir -p $(EFI_DIR)
@mkdir -p $(IMAGE_DIR)
# Compile source files
$(BUILD_DIR)/%.o: $(SRC_DIR)/%.c
@echo "Compiling $<..."
$(CC) $(CFLAGS) -c $< -o $@
# Link to create shared object
$(BUILD_DIR)/$(TARGET_SO): $(OBJ)
@echo "Linking $@..."
$(LD) $(LDFLAGS) $(OBJ) -o $@ $(LIBS)
# Convert to EFI application
$(EFI_DIR)/$(TARGET): $(BUILD_DIR)/$(TARGET_SO)
@echo "Creating EFI application..."
$(OBJCOPY) -j .text -j .sdata -j .data -j .dynamic \
-j .dynsym -j .rel -j .rela -j .reloc \
--target=efi-app-$(ARCH) $< $@
@echo "Build complete: $@"
# Run with QEMU
run: all
@echo "Starting QEMU..."
@echo "Using OVMF firmware: $(OVMF_CODE)"
@if [ ! -f $(BUILD_DIR)/OVMF_VARS.fd ]; then \
echo "Creating OVMF_VARS.fd from template..."; \
cp $(OVMF_VARS_TEMPLATE) $(BUILD_DIR)/OVMF_VARS.fd 2>/dev/null || \
dd if=/dev/zero of=$(BUILD_DIR)/OVMF_VARS.fd bs=1M count=64 2>/dev/null; \
fi
@echo "================================================"
@echo "QEMU is starting in nographic mode"
@echo "To exit QEMU: Press Ctrl+A, then X"
@echo "In the OS: Press 'q' to shutdown"
@echo "================================================"
$(QEMU) $(QEMU_FLAGS)
# Clean build artifacts
clean:
@echo "Cleaning build directory..."
rm -rf $(BUILD_DIR)
@echo "Clean complete."
# Install dependencies (for Debian/Ubuntu)
install-deps:
@echo "Installing dependencies..."
sudo apt-get update
sudo apt-get install -y gnu-efi qemu-system-x86 ovmf gcc binutils make
@echo "Dependencies installed."
# Help target
help:
@echo "UEFI Operating System Makefile"
@echo ""
@echo "Targets:"
@echo " all - Build the UEFI application (default)"
@echo " run - Build and run with QEMU"
@echo " clean - Remove build artifacts"
@echo " install-deps - Install required dependencies (Debian/Ubuntu)"
@echo " help - Display this help message"
@echo ""
@echo "Usage:"
@echo " make # Build the OS"
@echo " make run # Build and run in QEMU"
@echo " make clean # Clean build files"
@echo " make install-deps # Install dependencies"

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README.md Normal file
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# 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/)

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#include <efi.h>
#include <efilib.h>
EFI_STATUS
EFIAPI
efi_main(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
{
EFI_STATUS Status;
EFI_INPUT_KEY Key;
// Initialize the GNU-EFI library
InitializeLib(ImageHandle, SystemTable);
// Clear the screen
uefi_call_wrapper(ST->ConOut->ClearScreen, 1, ST->ConOut);
// Set text color to light green
uefi_call_wrapper(ST->ConOut->SetAttribute, 2, ST->ConOut,
EFI_TEXT_ATTR(EFI_LIGHTGREEN, EFI_BLACK));
// Print welcome messages
Print(L"================================================\n\r");
Print(L" Welcome to Simple UEFI Operating System!\n\r");
Print(L"================================================\n\r");
Print(L"\n\r");
Print(L"System Information:\n\r");
Print(L" UEFI Firmware Vendor: %s\n\r", ST->FirmwareVendor);
Print(L" UEFI Firmware Revision: %d.%d\n\r",
ST->FirmwareRevision >> 16, ST->FirmwareRevision & 0xFFFF);
Print(L"\n\r");
// Display some runtime services info
Print(L"Available Services:\n\r");
Print(L" - Console Input/Output: Active\n\r");
Print(L" - Runtime Services: Active\n\r");
Print(L" - Boot Services: Active\n\r");
Print(L"\n\r");
// Simple command loop
Print(L"Commands:\n\r");
Print(L" 'h' - Display help\n\r");
Print(L" 'i' - Display system info\n\r");
Print(L" 'c' - Clear screen\n\r");
Print(L" 'q' - Shutdown\n\r");
Print(L"\n\r");
Print(L"Press a key to start...\n\r");
while (TRUE) {
// Wait for key press
Status = uefi_call_wrapper(ST->ConIn->ReadKeyStroke, 2,
ST->ConIn, &Key);
if (EFI_ERROR(Status)) {
continue;
}
// Handle commands
if (Key.UnicodeChar == L'q' || Key.UnicodeChar == L'Q') {
Print(L"\n\rShutting down...\n\r");
// Reset the system
uefi_call_wrapper(RT->ResetSystem, 4, EfiResetShutdown,
EFI_SUCCESS, 0, NULL);
}
else if (Key.UnicodeChar == L'h' || Key.UnicodeChar == L'H') {
Print(L"\n\r=== Help ===\n\r");
Print(L"This is a minimal UEFI operating system.\n\r");
Print(L"It demonstrates basic UEFI functionality.\n\r");
Print(L"\n\r");
}
else if (Key.UnicodeChar == L'i' || Key.UnicodeChar == L'I') {
Print(L"\n\r=== System Info ===\n\r");
Print(L"Firmware Vendor: %s\n\r", ST->FirmwareVendor);
Print(L"Firmware Revision: %d.%d\n\r",
ST->FirmwareRevision >> 16, ST->FirmwareRevision & 0xFFFF);
Print(L"UEFI Specification: %d.%d\n\r",
ST->Hdr.Revision >> 16, ST->Hdr.Revision & 0xFFFF);
Print(L"\n\r");
}
else if (Key.UnicodeChar == L'c' || Key.UnicodeChar == L'C') {
uefi_call_wrapper(ST->ConOut->ClearScreen, 1, ST->ConOut);
Print(L"Screen cleared. Press 'h' for help.\n\r");
}
else if (Key.UnicodeChar >= 32 && Key.UnicodeChar < 127) {
// Echo printable characters
Print(L"%c", Key.UnicodeChar);
}
else if (Key.UnicodeChar == L'\r') {
Print(L"\n\r> ");
}
}
return EFI_SUCCESS;
}