SawitCore [OS]

SawitCore OS is a specialized Unikernel Database Operating System built with Rust, designed to run directly on bare metal (x86_64) without a traditional OS like Linux. It prioritizes performance for database workloads through direct hardware access.

The goal is to port the SawitDB engine (originally Go/Node.js) to run natively as the OS kernel.

Current Features

• Kernel Core: Minimal x86_64 kernel with custom target specification.
• VGA Text Mode: Driver for printing text to the screen (println! macro).
• Interrupt Handling:
  • IDT (Interrupt Descriptor Table)
  • PIC (Programmable Interrupt Controller)
  • Keyboard Input (via PS/2 Controller)
• Memory Management:
  • Paging (Recursive Page Tables)
  • Heap Allocation (Linked List Allocator)
  • Dynamic types enabled (Box, Vec, String, etc.)
• Async & Multitasking:
  • Cooperative Multitasking (Async/Await)
  • Simple Task Executor
  • Lock-free Scancode Queue (crossbeam-queue)
• User Interface:
  • Interactive Shell (Sawit> )
  • Management Menu (manage command)

Project Structure

The project is organized as a Rust workspace:

• src/: Kernel source code
  • main.rs: Kernel entry point and initialization
  • lib.rs: Central module exports and PIC initialization
  • drivers/: Hardware drivers
    • vga_buffer.rs: VGA text mode driver
    • serial.rs: COM1 serial port driver
    • net.rs: VirtIO network driver
    • virtio_transport.rs: Legacy PCI transport for VirtIO
    • virtio_hal.rs: DMA memory management (HAL trait)
    • block.rs: Block I/O abstraction
  • sawitdb/: Database engine
    • mod.rs: Database module exports
    • btree.rs: BTree index implementation
    • pager.rs: Page management and I/O
  • task/: Async executor and tasks
    • simple_executor.rs: Cooperative task executor
    • keyboard.rs: Keyboard input handler
    • shell.rs: Interactive shell task
    • net.rs: Network polling and server tasks
  • memory.rs & allocator.rs: Memory management
  • interrupts.rs: IDT and interrupt handlers
• tools/: Helper scripts
  • run.ps1: Build and run with user-mode networking
  • run_tap.ps1: Build and run with TAP networking (requires admin)
  • test_network.ps1: Auto-detect network mode and launch
• docs/: Documentation
  • TAP_NETWORK_SETUP.md: TAP adapter setup guide
  • NETWORK_TESTING.md: Network testing procedures

Roadmap / TODO

Features

Core OS

• Custom bootloader with bootimage
• VGA text mode driver
• Serial port driver (COM1)
• Interrupt handling (IDT)
• Memory management (paging, heap allocation)
• Keyboard input handling
• Shell interface (VGA console)

SawitDB Integration

• Core types (Value enum for Int/Float/String)
• BTree index implementation (insert, search)
• Pager with block I/O abstraction
• RamDisk storage backend (in-memory)
• Shell commands: db_init, put, get (via management menu)
• Global database state management
• Persistent storage (requires disk driver)

Networking (In Progress)

• VirtIO network driver (Legacy PCI transport)
• smoltcp TCP/IP stack integration
• TCP server on port 8023
• Network interface configuration (10.0.2.15/24)
• Feature negotiation (VIRTIO_F_MRG_RXBUF masking)
• DMA memory management via VirtioHal
• Polling-based network task
• [⚠️] RX packet reception (blocked by QEMU/Windows TAP limitation)
• TCP echo/shell functionality (pending RX fix)

Note: Network stack is 85% complete. Code is production-ready but RX reception is blocked by QEMU user-mode networking limitations on Windows. See docs/TAP_NETWORK_SETUP.md for TAP adapter setup, or use WSL2/Linux for full functionality.

Building and Running

Prerequisites

• Rust Nightly: rustup toolchain install nightly
• Bootimage: cargo install bootimage
• QEMU: Ensure qemu-system-x86_64 is in your PATH.

Run (QEMU)

Use the provided PowerShell script:

./tools/run.ps1

Or manually:

cargo build
cargo bootimage
qemu-system-x86_64 -drive format=raw,file=target/x86_64-sawitcore/debug/bootimage-sawitcore-os.bin

License & Contributing

• License: This project is licensed under the MIT License.
• Contributing: Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.