Bootldr Project

This project focuses on understanding how bootloaders work. It includes various stages and components to load an operating system.

Warning

This project is a work in progress and is not yet complete. It is not recommended for production use.

Core Components

• OS Loader: Loads the operating system (Unix family).
• GUI: Graphical user interface.
• Config: Configuration files and settings.

Installation

Currently, there is no installation process available.

Build Instructions

Prerequisites

• nasm (Netwide Assembler)
• ld (GNU Linker)
• gcc (GNU Compiler Collection)
• make (GNU Make)
• clang (LLVM Compiler)
• qemu (for running the bootloader)

Building the Bootloader

To build the bootloader, run the following command:

make

This will generate the bootloader binary in the build directory.

Build ELF file for Debugging

To build the ELF file for debugging, run:

make debug

Running the Bootloader in QEMU

TO run the bootloader in QEMU, run:

make run DEBUG=false

TO run the bootloader in QEMU with debugging enabled, run:

make run DEBUG=true

Cleaning the Build

To clean the build directory, run:

make clean

To-Do List

Click to expand

• Place the code in MBR (first sector of the disk)
• Setup 16-bit segment registers and stack
• Print startup message
• Enable and confirm enabled A20 line
• Load GDTR
• Setup GDT
• Enable 32-bit Protected Mode
• Call second stage C code
• Support GNU Multiboot
• Check presence of PCI, CPUID, MSRs
• Inform BIOS of target processor mode
• Get memory map from BIOS
• Locate kernel in filesystem
• Allocate memory to load kernel image
• Load kernel image into buffer
• Enable graphics mode
• Check kernel image ELF headers
• Allocate and map memory for kernel segments
• Setup COM serial output port
• Setup IDT
• Disable PIC
• Check presence of CPU features (NX, SMEP, x87, PCID, global pages, TCE, WP, MMX, SSE, SYSCALL), and enable them
• Assign a PAT to write combining
• Setup FS/GS base
• Load IDTR
• Enable APIC and setup using information in ACPI tables
• Setup TSS

Contribution

Contributions are welcome! Please fork the repository and submit a pull request.