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141 lines
7.5 KiB
Markdown
141 lines
7.5 KiB
Markdown
# SUB-OS 64-Bit Production Monolithic Operating System
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**SUB-OS** is a modular monolithic 64-bit x86_64 operating system designed and engineered from scratch following modern Linux kernel architectural patterns and incorporating the **LazyBox** multi-call userland binary suite.
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---
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## 🌟 Key Features
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- **64-Bit Long Mode Bare-Metal Core**: Custom two-stage MBR bootloader with BIOS E820 memory mapping and 4GB 4-level PML4 identity paging.
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- **Modular Monolithic Linux Layout**: Clean directory structure (`arch/`, `kernel/`, `mm/`, `drivers/`, `fs/`, `net/`, `crypto/`, `lib/`, `userland/`).
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- **Preemptive Multitasking Scheduler**: Round-Robin scheduling driven by 8254 PIT (100 Hz, 10ms resolution) with atomic spinlocks & semaphores.
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- **Physical & Dynamic Memory Management**: 64-bit Page Frame Allocator (4 KB bitmap) and Kernel Dynamic Heap (4 MB pool) with boundary tag splitting and coalescing.
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- **Virtual File System (VFS)**: Path resolver (`vfs_namei`), file descriptors (64 max), in-memory RAMFS, synthetic `/dev` device filesystem, and `/proc` dynamic system metrics filesystem.
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- **Hardware Drivers**:
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- **Char**: VGA Text Mode, Virtual Terminals TTY1-4 with ANSI escape parsing, 16550 UART Serial (COM1), PS/2 Keyboard with circular buffer.
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- **Block**: ATA / IDE Hard Disk PIO driver (28-bit LBA).
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- **PCI**: PCI Bus Enumeration & MMIO BAR configuration.
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- **Network**: Intel 82540EM/82545EM Gigabit Ethernet NIC with circular DMA RX/TX rings.
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- **Sound**: PC Speaker square-wave tone generator.
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- **Network Protocol Stack**: Ethernet encapsulation, ARP resolution table, IPv4 routing/checksums, and ICMP Echo client/server (`ping`).
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- **Kernel Cryptographic Engine**: FIPS 180-4 SHA-256, RFC 1321 MD5, IEEE 802.3 CRC32, and Xorshift128+ CSPRNG.
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- **LazyBox Multi-Call Userland Suite**: 42 built-in applets with history, arrow-key line editing, and ANSI color support.
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---
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## 📁 Source Tree
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```
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├── arch/x86_64/ # Hardware-specific CPU, paging, and entry code
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│ ├── boot/ # 64-bit kernel entry point (entry.asm)
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│ ├── cpu/ # GDT/TSS, IDT (256 gates), Dual 8259A PIC, 8254 PIT, CPUID
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│ └── mm/ # 4-Level PML4 Paging & TLB management
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├── boot/ # Custom two-stage MBR bootloader
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│ ├── boot.asm # Stage 1: 512-byte MBR loader (INT 13h LBA/CHS)
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│ └── stage2.asm # Stage 2: A20, E820 Memory Map, 4GB Identity Paging, Long Mode switch
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├── kernel/ # Core Monolithic Kernel Engine
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│ ├── main.c # 11-step master initialization sequence
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│ ├── printk.c # ANSI loglevel printk with 64KB dmesg ringbuffer & COM1 serial port output
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│ ├── panic.c # Kernel panic screen with 64-bit register dump
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│ ├── task.c # Task Control Blocks (PCB) & Process Management
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│ ├── sched.c # Preemptive Round-Robin Multi-Tasking Scheduler
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│ └── sync.c # Atomic spinlocks and semaphores
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├── mm/ # Memory Management Subsystem
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│ ├── pmm.c # 64-bit Physical Page Frame Allocator (4 KB bitmap)
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│ └── kmalloc.c # Kernel Dynamic Heap Allocator (4 MB initial pool)
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├── drivers/ # Device Driver Tree
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│ ├── char/ # VGA text driver, Virtual Terminals TTY1-4, 16550 UART COM1, PS/2 Keyboard
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│ ├── block/ # ATA / IDE Hard Disk PIO driver (28-bit LBA)
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│ ├── pci/ # PCI Bus Enumerator & BAR mapping
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│ ├── net/ # Intel 82540EM/82545EM Gigabit Ethernet NIC Driver (Circular DMA Rings)
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│ └── sound/ # PC Speaker tone generator & PIT Channel 2
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├── fs/ # Virtual File System (VFS)
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│ ├── vfs.c # VFS core, path resolver (vfs_namei), file descriptor table (64 max)
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│ ├── ramfs.c # In-memory RAM filesystem
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│ ├── devfs.c # Synthetic Device Filesystem (/dev/null, /dev/zero, /dev/random, /dev/tty)
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│ └── procfs.c # Dynamic Information Filesystem (/proc/version, /proc/meminfo, /proc/cpuinfo)
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├── crypto/ # Kernel Cryptographic Engine
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│ ├── sha256.c # FIPS 180-4 Standard SHA-256 Digest
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│ ├── md5.c # RFC 1321 MD5 Message-Digest
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│ ├── crc32.c # IEEE 802.3 32-bit Cyclic Redundancy Check
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│ └── prng.c # Xorshift128+ High-Performance CSPRNG
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├── net/core/ # Network Protocol Stack
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│ └── net.c # Ethernet encapsulation, ARP Table, IPv4 routing, ICMP Echo ping client/server
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├── lib/ # Standard Kernel Runtime Library
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│ ├── string.c # String & memory manipulation
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│ ├── vsprintf.c # vsnprintf with width, alignment, and formatting
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│ └── bitmap.c # Bit manipulation utilities
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└── userland/lazybox/ # Userland Shell & Multi-Call Suite
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├── lazybox.c # Multi-call binary dispatcher with 42 applets
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└── shell.c # Interactive terminal shell (history, tab-completion, ANSI color)
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```
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---
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## ⚡ 11-Step Master Boot Pipeline
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1. **[1/11] GDT & TSS**: 64-bit flat segment selectors + Task State Segment with dedicated 64KB kernel stack.
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2. **[2/11] IDT & ISRs**: 256-entry Interrupt Gate Table with CPU exception and hardware IRQ handlers.
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3. **[3/11] Dual 8259A PIC**: Remapped hardware IRQs 0-15 to vectors 32-47 with cascade handling.
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4. **[4/11] 8254 PIT Timer**: Configured for 100 Hz (10ms resolution) driving preemptive multitasking.
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5. **[5/11] PS/2 Keyboard**: Full scancode translation table with Shift, CapsLock, and circular buffer.
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6. **[6/11] Physical Memory Manager**: 64-bit frame allocator tracking 128 MB RAM (31,712 free pages).
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7. **[7/11] Kernel Dynamic Heap**: 4 MB initial pool with boundary tag headers, coalescing, and reallocation.
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8. **[8/11] ATA / IDE Hard Disk**: 28-bit LBA PIO controller supporting read/write operations.
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9. **[9/11] PCI & Intel E1000 NIC**: Intel Gigabit Ethernet controller (`52:54:00:12:34:56`), DMA RX/TX rings.
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10. **[10/11] Virtual File System**: Root RAMFS, `/dev` synthetic device filesystem, `/proc` dynamic info filesystem.
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11. **[11/11] LazyBox & Scheduler**: Preemptive scheduler initialization and interactive multi-call binary userland.
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---
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## 🛠️ Build and Run
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### Prerequisites
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- `nasm` (>= 2.15)
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- `x86_64-elf-gcc` (>= 13.0) & `x86_64-elf-ld`
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- `qemu-system-x86_64`
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- `make`
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### Commands
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```bash
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# Build the 1.5MB bootable disk image
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make
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# Launch in QEMU with Intel E1000 Gigabit NIC
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make run
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# Clean build artifacts
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make clean
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```
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---
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## 💻 LazyBox Applet Reference
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```
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[Filesystem]
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ls cat touch mkdir wc
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[Crypto]
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md5sum sha256sum crc32
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[Network]
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ifconfig ping arp
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[Storage]
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hdparm
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[System]
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uname free uptime dmesg sleep
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[Terminal]
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clear
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[Core]
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lazybox echo neofetch
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```
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---
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## 📄 License
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This project is open-source software licensed under the [MIT License](LICENSE).
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