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Kannaka Library / QuantumOS / QuantumOS Boot Process & Initialization Sequence
kannaka-labs/QuantumOS docs/BOOT_PROCESS.md · 2026-09-06 · source ↗ · edit ↗

⚠️ Historical design document. This predates the implementation and describes original intent, not the shipped system. For the as-built architecture see the Architecture Decision Records and the CHANGELOG; where they disagree with this file, they are correct.

QuantumOS Boot Process & Initialization Sequence

Boot Philosophy

Core Principles

  1. Deterministic Boot Sequence - Predictable initialization order
  2. Minimal Trusted Code - Smallest possible boot code base
  3. Hardware Abstraction Early - HAL initialized before kernel services
  4. Capability Root Establishment - Security foundation from first instruction
  5. Quantum Resource Enumeration - Early quantum hardware detection

Boot Phases Overview

┌─────────────────────────────────────────────────────────────┐
│                    Phase 0: Firmware                        │
│  • BIOS/UEFI (x86_64) or U-Boot (ARM/RISC-V)                │
│  • Hardware initialization                                   │
│  • Bootloader loading                                        │
└─────────────────────────────────────────────────────────────┘
                                │
                                ▼
┌─────────────────────────────────────────────────────────────┐
│                 Phase 1: Bootloader                          │
│  • Load kernel ELF image                                     │
│  • Setup basic paging (if needed)                            │
│  • Jump to kernel entry point                               │
└─────────────────────────────────────────────────────────────┘
                                │
                                ▼
┌─────────────────────────────────────────────────────────────┐
│                Phase 2: Kernel Bootstrap                     │
│  • Assembly entry point                                      │
│  • Basic CPU setup                                           │
│  • HAL initialization                                        │
│  • Memory management setup                                   │
└─────────────────────────────────────────────────────────────┘
                                │
                                ▼
┌─────────────────────────────────────────────────────────────┐
│              Phase 3: Core Services                          │
│  • Capability system initialization                           │
│  • IPC system setup                                          │
│  • Interrupt handling                                        │
│  • Process management                                        │
└─────────────────────────────────────────────────────────────┘
                                │
                                ▼
┌─────────────────────────────────────────────────────────────┐
│              Phase 4: User Space Services                   │
│  • Service manager startup                                   │
│  • Essential services (memory, scheduler, devices)           │
│  • Quantum services enumeration                             │
│  • Service registration                                      │
└─────────────────────────────────────────────────────────────┘
                                │
                                ▼
┌─────────────────────────────────────────────────────────────┐
│                 Phase 5: User Environment                    │
│  • Init process startup                                      │
│  • User interface (if any)                                   │
│  • System ready                                              │
└─────────────────────────────────────────────────────────────┘

Detailed Boot Sequence

Phase 0: Firmware Interface

x86_64 (BIOS/UEFI)

# boot/x86_64/boot.S
.section .text
.global _start

_start:
    # UEFI entry point
    # Firmware already in protected mode
    # Stack and basic setup done by UEFI
    jmp kernel_entry

ARM64 (U-Boot)

# boot/arm64/boot.S
.section .text
.global _start

_start:
    # ARM64 entry point
    # Setup stack pointer
    ldr x0, =stack_top
    mov sp, x0
    
    # Disable MMU and caches
    mrs x1, sctlr_el1
    bic x1, x1, #1          # Clear M bit
    msr sctlr_el1, x1
    
    # Jump to kernel
    bl kernel_entry

RISC-V (OpenSBI)

# boot/riscv64/boot.S
.section .text
.global _start

_start:
    # RISC-V entry point from OpenSBI
    # Setup stack
    la sp, stack_top
    
    # Jump to kernel
    tail kernel_entry

Phase 1: Bootloader Integration

Multiboot2 Specification (x86_64)

// boot/multiboot2.h
#define MULTIBOOT2_MAGIC 0x36d76289

typedef struct {
    uint32_t total_size;
    uint32_t reserved;
} multiboot_header_t;

// Boot information tags
typedef struct {
    uint32_t type;
    uint32_t size;
} multiboot_tag_t;

typedef struct {
    multiboot_tag_t tag;
    uint32_t mem_lower;
    uint32_t mem_upper;
} multiboot_tag_mem_t;

Device Tree (ARM64/RISC-V)

// boot/device_tree.h
typedef struct {
    uint32_t magic;           // 0xd00dfeed
    uint32_t total_size;
    uint32_t structure_offset;
    uint32_t strings_offset;
    uint32_t memory_reserve_map_offset;
} fdt_header_t;

// Device tree parsing
typedef struct {
    const char *name;
    const void *data;
    uint32_t size;
} fdt_node_t;

Phase 2: Kernel Bootstrap

Assembly Entry Point

// kernel/core/boot.S
.section .text
.global kernel_entry

kernel_entry:
    # Architecture-specific setup
    # Setup initial stack
    # Clear BSS
    # Call C initialization
    
    call c_kernel_init
    
    # Should never return
    hlt

C Initialization

// kernel/core/init.c
#include <kernel/types.h>
#include <hal/hal_common.h>

// Boot state tracking
typedef enum {
    BOOT_PHASE_FIRMWARE = 0,
    BOOT_PHASE_BOOTLOADER = 1,
    BOOT_PHASE_KERNEL = 2,
    BOOT_PHASE_SERVICES = 3,
    BOOT_PHASE_USERSPACE = 4,
    BOOT_PHASE_COMPLETE = 5
} boot_phase_t;

static boot_phase_t current_phase = BOOT_PHASE_FIRMWARE;

void c_kernel_init(void) {
    // Phase 2: Kernel Bootstrap
    current_phase = BOOT_PHASE_KERNEL;
    
    // Initialize HAL first
    hal_init();
    
    // Setup memory management
    memory_init();
    
    // Initialize interrupt system
    interrupts_init();
    
    // Setup capability system
    capabilities_init();
    
    // Initialize IPC
    ipc_init();
    
    // Start process management
    process_init();
    
    // Move to next phase
    init_core_services();
}

void init_core_services(void) {
    // Phase 3: Core Services
    current_phase = BOOT_PHASE_SERVICES;
    
    // Start service manager
    start_service_manager();
    
    // Initialize quantum subsystem
    quantum_init();
    
    // Start essential services
    start_essential_services();
    
    // Move to user space
    init_user_space();
}

Phase 3: Core Services Initialization

Capability System Bootstrap

// kernel/security/capabilities.c
// Root capability establishment
static capability_t root_capability;

void capabilities_init(void) {
    // Establish root capability with all permissions
    root_capability.cap_id = CAP_ROOT_ID;
    root_capability.owner_id = 0;  // Kernel
    root_capability.resource_id = 0;
    root_capability.permissions = CAP_ALL;
    root_capability.expiration = 0;  // Never expires
    root_capability.is_revocable = false;
    
    // Initialize capability allocator
    cap_allocator_init();
    
    // Create initial process capabilities
    create_kernel_capabilities();
}

IPC System Initialization

// kernel/ipc/ipc.c
void ipc_init(void) {
    // Initialize message queues
    message_queues_init();
    
    // Setup IPC system calls
    register_ipc_syscalls();
    
    // Create kernel IPC endpoints
    create_kernel_endpoints();
}

Phase 4: User Space Services

Service Manager Startup

// services/service_manager/main.c
int service_manager_main(void) {
    // Initialize service registry
    service_registry_init();
    
    // Start essential services in dependency order
    start_memory_manager();
    start_quantum_scheduler();
    start_device_manager();
    start_filesystem_service();
    
    // Register quantum services
    enumerate_quantum_services();
    
    // Accept service registrations
    accept_service_registrations();
    
    // Signal system ready
    signal_system_ready();
    
    return 0;
}

Essential Service Startup Sequence

// services/service_manager/startup.c
typedef struct {
    const char *service_name;
    uint32_t priority;
    uint32_t dependencies[8];
    uint32_t timeout_ms;
} service_startup_info_t;

static service_startup_info_t essential_services[] = {
    {"memory-manager", 1, {}, 5000},
    {"quantum-scheduler", 2, {0}, 10000},  // Depends on memory-manager
    {"device-manager", 3, {0}, 15000},    // Depends on memory-manager
    {"filesystem", 4, {0, 2}, 20000},      // Depends on memory-manager, quantum-scheduler
};

void start_essential_services(void) {
    for (int i = 0; i < ARRAY_SIZE(essential_services); i++) {
        start_service(&essential_services[i]);
    }
}

Phase 5: User Environment

Init Process

// userspace/init/main.c
int init_main(void) {
    // Wait for all services to be ready
    wait_for_services_ready();
    
    // Mount essential filesystems
    mount_root_filesystem();
    
    // Start system daemons
    start_system_daemons();
    
    // Initialize quantum environment
    init_quantum_environment();
    
    // Start user interface (if configured)
    if (config_has_ui()) {
        start_user_interface();
    }
    
    // System is now ready
    log_info("QuantumOS v%s ready", QUANTUMOS_VERSION);
    
    // Enter main loop
    init_main_loop();
    
    return 0;
}

Quantum Hardware Enumeration

Early Quantum Detection

// kernel/quantum/enumeration.c
typedef struct {
    uint32_t hardware_type;
    uint32_t qubit_count;
    uint64_t coherence_time;
    uint32_t fidelity;
    char vendor[32];
    char model[64];
} quantum_hardware_info_t;

void quantum_init(void) {
    quantum_hardware_info_t hw_info;
    
    // Detect quantum hardware
    if (hal_quantum_detect(&hw_info) == HAL_SUCCESS) {
        log_info("Quantum hardware detected: %s %s", hw_info.vendor, hw_info.model);
        log_info("Qubits: %d, Coherence: %lld ns, Fidelity: %d.%02d%%",
                 hw_info.qubit_count, hw_info.coherence_time,
                 hw_info.fidelity / 100, hw_info.fidelity % 100);
        
        // Register quantum resources
        register_quantum_resources(&hw_info);
        
        // Start quantum scheduler service
        start_quantum_scheduler_service();
    } else {
        log_info("No quantum hardware detected, using simulator");
        init_quantum_simulator();
    }
}

Boot Configuration

Boot Parameters

// boot/config.h
typedef struct {
    char kernel_cmdline[1024];
    uint32_t debug_level;
    uint32_t max_memory;
    uint32_t quantum_simulator_qubits;
    char root_device[64];
    uint32_t boot_timeout;
} boot_config_t;

// Default configuration
static boot_config_t default_config = {
    .kernel_cmdline = "quiet",
    .debug_level = 1,
    .max_memory = 0,  // Use all available
    .quantum_simulator_qubits = 32,
    .root_device = "/dev/mem0",
    .boot_timeout = 30000,  // 30 seconds
};

Configuration Sources

  1. Firmware Settings - UEFI variables, device tree properties
  2. Bootloader Parameters - Command line arguments
  3. Kernel Configuration - Compile-time defaults
  4. Runtime Configuration - Environment variables

Boot Time Optimization

Parallel Initialization

// kernel/core/parallel_init.c
typedef struct {
    void (*init_func)(void);
    const char *name;
    uint32_t dependencies[4];
} init_task_t;

static init_task_t init_tasks[] = {
    {hal_init, "HAL", {}},
    {memory_init, "Memory", {0}},                    // Depends on HAL
    {interrupts_init, "Interrupts", {0}},           // Depends on HAL
    {capabilities_init, "Capabilities", {1, 2}},     // Depends on Memory, Interrupts
    {ipc_init, "IPC", {1, 3}},                      // Depends on Memory, Capabilities
    {quantum_init, "Quantum", {1, 2}},             // Depends on Memory, Interrupts
};

void parallel_init(void) {
    // Create initialization graph
    // Execute independent tasks in parallel
    // Wait for dependencies
    // Continue until all tasks complete
}

Boot Time Targets

  • Firmware to Kernel: < 100ms
  • Kernel Bootstrap: < 50ms
  • Core Services: < 200ms
  • User Space Services: < 500ms
  • Total Boot Time: < 1 second (target), < 5 seconds (maximum)

Boot Failure Recovery

Error Handling

// kernel/core/boot_error.c
typedef enum {
    BOOT_SUCCESS = 0,
    BOOT_ERROR_HAL_INIT = -1,
    BOOT_ERROR_MEMORY_INIT = -2,
    BOOT_ERROR_INTERRUPT_INIT = -3,
    BOOT_ERROR_SERVICE_START = -4,
    BOOT_ERROR_QUANTUM_INIT = -5,
    BOOT_ERROR_TIMEOUT = -6
} boot_result_t;

void boot_error_handler(boot_result_t error) {
    log_error("Boot failed with error: %d", error);
    
    // Try recovery strategies
    switch (error) {
        case BOOT_ERROR_HAL_INIT:
            // Try alternative HAL implementation
            break;
        case BOOT_ERROR_MEMORY_INIT:
            // Fall back to minimal memory configuration
            break;
        case BOOT_ERROR_SERVICE_START:
            // Try starting services individually
            break;
        default:
            // Enter recovery mode
            enter_recovery_mode();
    }
}

Recovery Mode

// kernel/core/recovery.c
void enter_recovery_mode(void) {
    log_info("Entering recovery mode");
    
    // Minimal initialization
    minimal_hal_init();
    minimal_memory_init();
    minimal_interrupts_init();
    
    // Start recovery shell
    start_recovery_shell();
    
    // Wait for user intervention
    while (1) {
        halt();
    }
}

Implementation Structure

Boot Files Organization

boot/
├── common/
│   ├── boot_common.h        # Common boot definitions
│   ├── multiboot2.c         # Multiboot2 support (x86_64)
│   ├── device_tree.c        # Device tree parsing (ARM/RISC-V)
│   └── config.c             # Boot configuration
├── x86_64/
│   ├── boot.S              # Assembly entry point
│   ├── multiboot_header.S  # Multiboot2 header
│   └── uefi.c              # UEFI interface
├── arm64/
│   ├── boot.S              # Assembly entry point
│   ├── uefi.c              # UEFI for ARM64
│   └── device_tree.c       # Device tree parsing
└── riscv64/
    ├── boot.S              # Assembly entry point
    ├── opensbi.c            # OpenSBI interface
    └── device_tree.c       # Device tree parsing

kernel/core/
├── boot.S                  # Architecture-independent boot
├── init.c                  # C initialization
├── parallel_init.c         # Parallel initialization
├── boot_error.c            # Error handling
└── recovery.c              # Recovery mode

kernel/include/
├── boot.h                  # Boot interface
├── config.h                # Configuration
└── recovery.h              # Recovery interface

Success Criteria

  • System boots on all supported architectures
  • HAL initialization completes successfully
  • All essential services start within timeout
  • Quantum hardware is detected and initialized
  • Capability system is established before user space
  • Boot time meets performance targets
  • Recovery mode works for common failure scenarios
  • Boot configuration is flexible and extensible

This boot process design provides a robust, deterministic foundation for QuantumOS while supporting the diverse hardware landscape and quantum-aware features required by the system architecture.