Phase 1: Microkernel Core

Status: COMPLETE ✅ - 100% Overall
Started: June 8, 2025
Completed: June 12, 2025
Released: v0.2.0 (June 12, 2025), v0.2.1 (June 17, 2025)
Last Updated: June 17, 2025
Goal: Implement the core microkernel functionality with high-performance IPC, memory management, and scheduling.

Overview

Phase 1 focuses on implementing the essential microkernel components that must run in privileged mode. This includes memory management, inter-process communication, process scheduling, and the capability system that underpins all security in VeridianOS.

Hybrid Design: Buddy allocator for ≥2MB, bitmap for <2MB allocations
Performance Target: <1μs allocation latency
NUMA Support: Per-node allocators with distance-aware allocation
Memory Zones: DMA (0-16MB), Normal, and Huge Page zones

#![allow(unused)]
fn main() {
pub struct HybridAllocator {
    bitmap: BitmapAllocator,      // For allocations < 512 frames
    buddy: BuddyAllocator,        // For allocations ≥ 512 frames
    threshold: usize,             // 512 frames = 2MB
    numa_nodes: Vec<NumaNode>,    // NUMA topology
}
}

Virtual Memory Management

Page Tables: 4-level (x86_64), 3-level (RISC-V), 4-level (AArch64)
Address Spaces: Full isolation between processes
Huge Pages: 2MB and 1GB transparent huge page support
Features: W^X enforcement, ASLR, guard pages

2. Inter-Process Communication (Weeks 9-12)

IPC Architecture

Three-Layer Design:
1. POSIX API Layer (compatibility)
2. Translation Layer (POSIX to native)
3. Native IPC Layer (high performance)

Performance Targets

Small Messages (≤64 bytes): <1μs using register passing
Large Transfers: <5μs using zero-copy shared memory
Throughput: >1M messages/second

Implementation Details

#![allow(unused)]
fn main() {
pub enum IpcMessage {
    Sync {
        data: [u8; 64],           // Register-passed data
        caps: [Capability; 4],    // Capability transfer
    },
    Async {
        buffer: SharedBuffer,     // Zero-copy buffer
        notify: EventFd,          // Completion notification
    },
}
}

3. Process Management (Weeks 13-16)

Process Model

Threads: M:N threading with user-level scheduling
Creation: <100μs process creation time
Termination: Clean resource cleanup with capability revocation

Context Switching

Target: <10μs including capability validation
Optimization: Lazy FPU switching, minimal register saves
NUMA: CPU affinity and cache-aware scheduling

4. Scheduler Implementation (Weeks 17-20)

Multi-Level Feedback Queue

Priority Levels: 5 levels with dynamic adjustment
Time Quanta: 1ms to 100ms based on priority
Load Balancing: Work stealing within NUMA domains

#![allow(unused)]
fn main() {
pub struct Scheduler {
    ready_queues: [VecDeque<Thread>; 5],  // Priority queues
    cpu_masks: Vec<CpuSet>,               // CPU affinity
    steal_threshold: usize,               // Work stealing trigger
}
}

Real-Time Support

Priority Classes: Real-time, normal, idle
Deadline Scheduling: EDF for real-time tasks
CPU Reservation: Dedicated cores for RT tasks

5. Capability System (Weeks 21-24)

Token Structure

#![allow(unused)]
fn main() {
pub struct Capability {
    cap_type: u16,      // Object type (process, memory, etc.)
    object_id: u32,     // Unique object identifier
    rights: u16,        // Read, write, execute, etc.
    generation: u16,    // Prevents reuse attacks
}
}

Implementation Requirements

Lookup: O(1) using hash tables with caching
Validation: <100ns for capability checks
Delegation: Safe capability subdivision
Revocation: Recursive invalidation support

6. System Call Interface (Weeks 25-26)

Minimal System Calls (~50 total)

#![allow(unused)]
fn main() {
// Core system calls
sys_cap_create()      // Create new capability
sys_cap_derive()      // Derive sub-capability
sys_cap_revoke()      // Revoke capability tree
sys_ipc_send()        // Send IPC message
sys_ipc_receive()     // Receive IPC message
sys_mem_map()         // Map memory region
sys_thread_create()   // Create new thread
sys_thread_yield()    // Yield CPU
}