Architecture Overview

VeridianOS is designed as a modern microkernel operating system with a focus on security, modularity, and performance. This chapter provides a comprehensive overview of the system architecture.

Architecture Goals

  • Microkernel size: < 15,000 lines of code
  • IPC latency: < 1μs for small messages, < 5μs for large transfers
  • Context switch time: < 10μs
  • Process support: 1000+ concurrent processes
  • Memory allocation: < 1μs latency
  • Capability lookup: O(1) time complexity

Core Design Principles

  1. Microkernel Architecture: Minimal kernel with services in user space
  2. Capability-Based Security: Unforgeable tokens for all resource access
  3. Memory Safety: Written entirely in Rust with minimal unsafe code
  4. Zero-Copy Design: Efficient data sharing without copying
  5. Hardware Abstraction: Clean separation between architecture-specific and generic code
  6. Performance First: Design decisions prioritize sub-microsecond operations

System Layers

┌─────────────────────────────────────────────────────────────┐
│                    User Applications                        │
├─────────────────────────────────────────────────────────────┤
│                    System Services                          │
│  ┌─────────┐  ┌─────────┐  ┌─────────┐  ┌─────────┐       │
│  │   VFS   │  │ Network │  │ Display │  │  Audio  │       │
│  │ Service │  │  Stack  │  │ Server  │  │ Server  │       │
│  └─────────┘  └─────────┘  └─────────┘  └─────────┘       │
├─────────────────────────────────────────────────────────────┤
│                    User-Space Drivers                       │
│  ┌─────────┐  ┌─────────┐  ┌─────────┐  ┌─────────┐       │
│  │  Block  │  │   Net   │  │   GPU   │  │   USB   │       │
│  │ Drivers │  │ Drivers │  │ Drivers │  │ Drivers │       │
│  └─────────┘  └─────────┘  └─────────┘  └─────────┘       │
├─────────────────────────────────────────────────────────────┤
│                      Microkernel                            │
│  ┌─────────┐  ┌─────────┐  ┌─────────┐  ┌─────────┐       │
│  │ Memory  │  │  Task   │  │   IPC   │  │   Cap   │       │
│  │  Mgmt   │  │  Sched  │  │ System  │  │ System  │       │
│  └─────────┘  └─────────┘  └─────────┘  └─────────┘       │
└─────────────────────────────────────────────────────────────┘

Microkernel Components

The microkernel contains only the essential components that must run in privileged mode:

Memory Management

  • Physical and virtual memory allocation
  • Page table management
  • Memory protection and isolation
  • NUMA-aware allocation
  • Hardware memory features (huge pages, CXL, memory tagging)

Task Scheduling

  • Process and thread management
  • CPU scheduling with multi-level feedback queue
  • Real-time scheduling support
  • CPU affinity and NUMA optimization
  • Power management integration

Inter-Process Communication

  • Synchronous message passing
  • Asynchronous channels
  • Shared memory regions
  • Capability passing
  • Zero-copy transfers

Capability System

  • Capability creation and validation
  • Access control enforcement
  • Hierarchical delegation
  • Revocation support

User-Space Architecture

All non-essential services run in user space for better isolation and reliability:

System Services

  • Virtual File System: Unified file access interface
  • Network Stack: TCP/IP implementation with zero-copy
  • Display Server: Wayland compositor with GPU acceleration
  • Audio Server: Low-latency audio routing and mixing

Device Drivers

  • Run as isolated user processes
  • Communicate via IPC with kernel
  • Direct hardware access through capabilities
  • Interrupt forwarding from kernel
  • DMA buffer management

Security Architecture

Security is built into every layer of the system:

  1. Hardware Security: Support for Intel TDX, AMD SEV-SNP, ARM CCA
  2. Capability-Based Access: All resources protected by capabilities
  3. Memory Safety: Rust prevents memory corruption vulnerabilities
  4. Process Isolation: Full address space isolation between processes
  5. Secure Boot: Cryptographic verification of boot chain

Performance Characteristics

VeridianOS is designed for high performance on modern hardware:

  • Lock-Free Algorithms: Used throughout for scalability
  • Cache-Aware Design: Data structures optimized for cache locality
  • NUMA Optimization: Memory allocation considers NUMA topology
  • Zero-Copy IPC: Data shared without copying
  • Fast Context Switching: Minimal state saved/restored

Platform Support

VeridianOS supports multiple hardware architectures:

  • x86_64: Full support with all features
  • AArch64: ARM 64-bit with security extensions
  • RISC-V: RV64GC with standard extensions

Each platform has architecture-specific optimizations while sharing the majority of the codebase.

Next Steps