Krexo v1.2.1

Krexo is a high-performance x86_64 bootloader for BIOS and UEFI. It uses a request-based protocol to pass system information to the kernel, allowing for a decoupled architecture where the kernel defines its requirements via ELF sections.

Major Changes in v1.2.x

• Limine Compatibility: Started support for Limine protocol requests (Framebuffer, Memory Map, HHDM, etc.).
• UI: Enhanced boot menu with background image support (BMP/PNG) and flicker-free rendering.
• Memory Management: Improved memory map generation and HHDM support for both protocols.

Features

• Dual-Mode Boot: Supports legacy BIOS (VBE) and modern UEFI (GOP) with high-resolution graphics.
• Interactive Menu: Fully configurable boot menu with automatic countdown and custom themes.
• Protocol Support:
  • Native Krexo: A request-based interface declarations via ELF sections.
  • Limine Compat: Support for Limine protocol requests (Framebuffer, Memory Map, HHDM, etc.).
• FAT32 Support: Built-in stack for loading the kernel and krexo.conf from the boot partition.
• Memory Safety: No-flicker UI using partial redraws (dirty stripes).

Roadmap

We are working on expanding Krexo's capabilities:

• SMP Support: Symmetrical Multiprocessing to wake up and manage multiple CPU cores.
• Multiboot2 Support: Implementation of the Multiboot2 protocol for broader kernel interoperability.
• Linux-Boot: Direct support for loading Linux kernels (bzImage) and initrd.
• Limine-Protocol: Direct support for Limine protocol requests (Framebuffer, Memory Map, HHDM, etc.).
• Advanced Filesystems: Adding read support for EXT4 and ISO9660.
• Security: UEFI Secure Boot support and signature verification.

Directory Structure

• src/bios/: 16-bit Stage 1 and 32-bit Stage 2 loaders.
• src/uefi/: 64-bit EFI application.
• src/common/: Shared logic for filesystems, protocols, and rendering.
• include/: Common headers for bootloader and kernel.
• barebones/: Reference kernel implementations.

Build and Run

Dependencies

• Toolchain: nasm, x86_64-elf-gcc, clang, lld-link
• Emulation: qemu-system-x86_64, OVMF

Execution

BIOS:

make clean && make run_bios

UEFI:

make clean && make run_uefi

Kernel Specification

The kernel specifies requirements using structures in the .krexo_requests ELF section (Native) or via Limine tags.

#include <common/requests.h>

__attribute__((section(".krexo_requests")))
volatile krexo_fb_request_t fb_request = {
    .header = { 
        .magic = { KREXO_REQUEST_MAGIC_0, KREXO_REQUEST_MAGIC_1 },
        .id = KREXO_FB_REQUEST_ID, 
        .response = 0 
    }
};

On handover, the response pointer will contain the address of the fulfilled hardware information.