Kernel architecture

AuriOS is a 32-bit monolithic kernel, booted via Multiboot (GRUB), running in protected mode on x86.

Boot overview

graph TD
    A[GRUB / Multiboot] --> B[loader.s]
    B --> C[kernel_main]
    C --> D[GDT / PIC / IDT]
    D --> E[Terminal + Timer]
    E --> F[PMM + MMU paging]
    F --> G[Keyboard]
    G --> H[Interactive shell]

On startup, GRUB loads the kernel via Multiboot and hands execution to loader.s, which calls kernel_main. The kernel then sets up the CPU tables (GDT, PIC remapping, IDT), initializes the terminal and the timer, then enables interrupts. It next configures memory (PMM then MMU paging), initializes the keyboard and hands control to the interactive shell.

CPU components

• GDT (Global Descriptor Table) — defines the memory segments (src/cpu/gdt.c).
• IDT (Interrupt Descriptor Table) — table of interrupt vectors, with the service routines (ISR) and the IRQ handlers.
• PIC — the programmable interrupt controller is remapped to avoid conflicts with CPU exceptions.

Memory management

1. PMM (Physical Memory Manager) — tracks free / used physical pages via a bitmap, initialized from the memory map provided by the Multiboot bootloader.
2. MMU / Paging — enables hardware paging; a page fault on an unmapped region is blocked (testable with the mia command).
3. Kernel heap — malloc / free provide dynamic allocation (src/lib/malloc.c).

Drivers

• Keyboard — reads scancodes via IRQ1 (src/drivers/keyboard.c).
• Timer (PIT) — configured at 1000 Hz, provides get_tick() and sleep().
• Serial — log output on the serial port (useful in iso-debug).
• Framebuffer / terminal — VGA text display with colors and ANSI escape sequences.

Logging

The kernel exposes logging macros (KINFO, KPANIC) defined in src/include/log.h. In AURI_TEST_MODE, output is redirected to the serial port.