Conductor Microkernel Architecture

What is a Microkernel?

A microkernel is an operating system design where the kernel provides only the most essential services, while all other functionality runs as separate processes (services) in userspace. This is opposite to monolithic kernels where everything runs in kernel space with full privileges.

Core Philosophy: Keep the kernel minimal, secure, and stable. Push complexity to userspace where it can't crash the system.

🧠 Core Microkernel Components

1. Microkernel Core

The absolute minimal kernel that cannot be removed or run in userspace.

class MicrokernelCore {
    // The heart of the system - coordinates everything
    function boot() {
        initialize_memory_manager()
        initialize_scheduler()
        initialize_ipc_system()
        initialize_interrupt_handler()
        start_initial_services()
    }

    function shutdown() {
        notify_all_services()
        cleanup_resources()
        halt_system()
    }
}

Why it can't be userspace: Someone needs to have ultimate authority over hardware and process creation.

2. Memory Management Subsystem

Manages virtual memory, physical memory allocation, and memory protection.

class MemoryManager {
    function allocate_virtual_memory(process_id, size, permissions) {
        // Allocate virtual address space for a process
        virtual_address = find_free_virtual_range(size)
        physical_pages = allocate_physical_pages(size)
        map_virtual_to_physical(virtual_address, physical_pages, permissions)
        return virtual_address
    }

    function free_memory(process_id, virtual_address) {
        // Free both virtual and physical memory
        physical_pages = get_physical_mapping(virtual_address)
        unmap_virtual_address(virtual_address)
        free_physical_pages(physical_pages)
    }

    function protect_memory(virtual_address, new_permissions) {
        // Change memory protection (read/write/execute)
        update_page_table_permissions(virtual_address, new_permissions)
        flush_tlb() // Translation Lookaside Buffer
    }

    function share_memory(process1_id, process2_id, size) {
        // Allow two processes to share memory region
        physical_pages = allocate_physical_pages(size)
        map_to_process(process1_id, physical_pages)
        map_to_process(process2_id, physical_pages)
    }
}

Critical for microkernel: Services need isolated memory spaces, but also controlled sharing for IPC.

3. Process/Thread Scheduler

Decides which process runs when and manages CPU time allocation.

class Scheduler {
    queue ready_queue
    queue blocked_queue
    process current_process

    function schedule_next() {
        // Choose next process to run
        if (ready_queue.is_empty()) {
            run_idle_process()
        } else {
            next_process = ready_queue.dequeue()
            context_switch(current_process, next_process)
            current_process = next_process
        }
    }

    function create_process(executable_path, priority, memory_limit) {
        process = new Process()
        process.load_executable(executable_path)
        process.allocate_memory(memory_limit)
        process.set_priority(priority)
        ready_queue.enqueue(process)
        return process.process_id
    }

    function block_process(process_id, reason) {
        // Move process from ready to blocked state
        process = find_process(process_id)
        ready_queue.remove(process)
        blocked_queue.add(process, reason)
    }

    function unblock_process(process_id) {
        // Move process from blocked back to ready
        process = blocked_queue.remove(process_id)
        ready_queue.enqueue(process)
    }

    function terminate_process(process_id) {
        process = find_process(process_id)
        cleanup_process_resources(process)
        remove_from_all_queues(process)
    }
}

Why essential: Without scheduling, multiple services can't coexist and share CPU time fairly.