Skip to main content

PivotOS

PivotOS is a custom 64 bit operating system built in Zig and x86 Assembly.

Features​

  • Physical Memory Manager (PMM)
    • Responsible for allocating physical pages (4096 bytes) to the kernel
    • Uses custom linked list allocator that runs in O(1) time
  • Page Table Mapper
    • Responsible for interacting with the CPU's page tables
    • Runs in O(1) time
  • Virtual Memory Manager
    • Responsible switching between page tables and handling a process's virtual memory
    • Uses custom buddy allocator that runs in O(log n) time
  • Kernel Heap Manager
    • Responsible for managing the heap memory for the kernel
    • Uses Zig's standard FixedBufferAllocator
    • Runs in O(1) time
  • ACPI Support - Interfaces with uACPI to learn about the hardware properties of the host
  • Timer Support - Supports the LAPIC, PIT, HPET, and ACPI timer
  • PCI(e) Support - Supports both PCIe and legacy PCI
  • UART 16550 (Serial) Driver - Uses serial port to communicate to QEMU
  • Framebuffer Support - Uses SSFN to draw fonts to the framebuffer
  • Multiprocessing - Uses Limine to start other processors and run code on them
  • Multitasking - Uses custom real-time scheduler to run processes
  • Virtual File System (in progress) - Linux inspired virtual file system to handle multiple filesystem types
  • Disk Driver (in progress) - Custom driver for ACHI/IDE
  • Network Driver (in progress) - Driver for virtio-net backed by LWIP

Technologies Used​

  • Limine
    • Used as the bootloader of PivotOS
    • Originally used a custom bootloader, but quickly became too much effort for very little gain
  • uACPI
    • Used as the API for ACPI support
    • Infeasible to build custom ACPI support because of the complexity of ASL parsing (ACPI language)
    • Called by Zig through SysV ABI compatibility layer
  • LWIP
    • Used as the API for network support
    • Infeasible to build custom network stack because of the complexity of network protocols
    • Called by Zig through SysV ABI compatibility layer
  • SSFN
    • Used as the API for framebuffer support
    • Used instead of custom framebuffer implementation because of the complexity of font rendering and optimization
    • Called by Zig through SysV ABI compatibility layer
  • Limine Zig
    • Used as the API for interacting with Limine boot protocol structures
    • Written in native Zig

Revisions​