povOS is an operating system for an IBM-compatible PC using the x86_64 architecture.

• Author: Giovanni Santini
• Mail: giovanni.santini@proton.me
• License: MIT

Features

• custom bootloader
• custom standard library
• kernel:
  • IDT (Interrupt Descriptor Tabe) and ISR (Interrupt Service Routines)
  • input (supports multiple keyboard layouts)
  • textbuffer
  • framebuffer
  • console
  • tty
  • time tracking
  • sleep
  • memory management
    • physical memory management
    • paging
    • virtual memory manager
    • free-list based memory allocator
    • heap
    • higher half kernel, RAM mapped in high memory
  • multitasking
    • tasks
    • context switching
    • scheduler
    • semaphores
    • mutexes
    • spinlocks
  • filesystem
    • virtual filesystem
  • random number generation
• drivers:
  • PS/2
  • UART
  • VGA
  • ISA
  • ATA
  • PIC (Programmable Interrupt Controller)
  • PIT (Programmable Interrupt Timer)
  • HPET (High Precision Event Timer)
  • Keyboard
  • ACPI
  • PCI/PCIe
  • edu
  • IOAPIC

The implementation is clean and readable, headers are documentation.

General overview of the programming environment:

Usage

Compile and run with qemu:

make -B && make qemu

Compile and run with bochs:

make -B && make bochs

Run inside GDB (with debug info):

./scripts/debug x86_64

The boot sequence

The BIOS boot sequence for x86_64 looks like this:

• CPU starts executing in 16-bit real mode, with BIOS access
• Use the bios to load the rest of the bootloader and kernel
• Setup and load the GDT with a flat memory layout
• Go to protected mode
• Enable the A20 line
• Setup GDT again
• Setup the page table
• Enable long mode
• Call the main routine