# 🌟 opencoreC: High-Performance x86_64 Microkernel OS

<div align="center">

```text
         ___                 root@opencoreC
       /     \               -----------------
      |  (o)  |  ___         OS: opencoreC Microkernel x86_64
      |       | /   \        Kernel: v0.1.0-release (Rust #![no_std])
       \ ___ / | (o) |       Uptime: 42 mins, 12 secs
                \___/        Shell: osh (opencore shell 1.0)
    [=== opencoreC ===]      Display: 1280x800 @ 60Hz 32bpp (Linear FB)
        x86_64 SMP           DE / WM: LVGL v8.3 Windows/KDE Compositor
       Ring 3 Userspace      CPU: QEMU Virtual CPU (4 Cores SMP)
      Fast-Path IPC Cap      Memory: 38 MiB / 509 MiB (7%)
                             Network: Realtek RTL8139 (10.0.2.15)
                             ACPI: S5 Poweroff, Reset, MADT 4 Cores
                             Security: Ring 3 Signal Fault Isolation (SIGSEGV)
                             Entropy: Hardware RNG (RDRAND / TSC)
```

[![Architecture](https://img.shields.io/badge/Architecture-x86__64%20(Long%20Mode)-007acc?style=for-the-badge&logo=cpu)]()
[![Kernel](https://img.shields.io/badge/Kernel-Rust%20%23!%5Bno__std%5D-dea584?style=for-the-badge&logo=rust)]()
[![User Space](https://img.shields.io/badge/User%20Space-C%2B%2B20%20%26%20C11-00599c?style=for-the-badge&logo=c%2B%2B)]()
[![GUI](https://img.shields.io/badge/GUI-LVGL%20v8.3%20Windows%2FKDE-4ba3e3?style=for-the-badge)]()
[![SMP](https://img.shields.io/badge/Multi--Core-SMP%204%20Cores-brightgreen?style=for-the-badge)]()
[![Network](https://img.shields.io/badge/Network-RTL8139%20PCI%20DMA-orange?style=for-the-badge)]()
[![Bootloader](https://img.shields.io/badge/Boot-Limine%20BIOS%20%2B%20UEFI-success?style=for-the-badge)]()
[![License](https://img.shields.io/badge/License-MIT%20%2F%20Apache--2.0-yellow?style=for-the-badge)]()

<p align="center">
  <b>A state-of-the-art, capability-based microkernel operating system written in Rust and modern C++20.</b><br>
  Designed from scratch for x86_64 long mode, featuring SMP multi-core affinity, an LVGL-powered desktop compositor, hardware ACPI power management, hardware random generation, and fault-tolerant process signal isolation.
</p>

</div>

---

## 🚀 Key Highlights & Subsystems

### ⚡ 1. SMP Multi-Core & Core Affinity Optimization
* **Application Processor Startup:** Secondary cores (Core 1, 2, 3) are booted via the Limine SMP protocol with dedicated TSS descriptors (`PER_CPU_TSS`), GDT, IDT, SSE/AVX registers, and fast-path syscall MSRs (`IA32_LSTAR`, `IA32_STAR`, `IA32_FMASK`).
* **Fast Non-Locking CPU ID:** Uses CPU MSR `0xC0000103` (`IA32_TSC_AUX`) to retrieve the current physical core index in a single assembly instruction (`rdmsr`).
* **Dedicated Core Affinity:**
  - **Core 0:** Microkernel Core, Hardware Timer PIT (100 Hz), Hardware IRQs (Mouse, Keyboard, RTL8139 NIC).
  - **Core 1:** Dedicated to **`gui_server`** — 60 FPS graphics rendering without lag or priority inversions.
  - **Core 2:** Dedicated to **`sh`** (Interactive shell and command execution).
  - **Core 3:** Dedicated to background servers (`init_server`, `uart_driver`, `procmgr`).

### 🪟 2. LVGL v8.3 Windows/KDE Desktop GUI
* **Hardware PS/2 Mouse Tracking:** Smooth double-buffered cursor rendering at 1280x800 resolution directly over Limine linear framebuffer (`0x80000000`).
* **Zero-Lag Window Dragging:** High-performance dirty-region raster bands (`BUF_HEIGHT = 80`) and optimized composition.
* **Windows 11 / KDE Plasma Aesthetic:**
  - Glassmorphic Taskbar with Start Menu button, running task chips, and live CMOS digital clock.
  - Interactive Start Menu with quick application launcher and system power controls.
  - **Task Manager / Resource Monitor:** Real-time multi-core CPU utilization meters across all 4 cores and physical memory progress bar.
  - **Linux-style Graphical Terminal:** Dark-mode terminal with blinking cursor and full command interpreter.
  - **About System & Network Diagnostics Center:** Real-time RTL8139 MAC, IP, and packet counters.

### 🌐 3. Realtek RTL8139 PCI Fast Ethernet Network
* **PCI Bus Mastering:** Auto-probes PCI bus `0:2:0`, enables Bus Master DMA.
* **Zero-Copy Physical DMA:** Configured with physical transmit and receive ring buffers (`0x90000000`).
* **Network Stack:** Full ARP request/reply, IPv4 packet parsing, and ICMP Echo transmission (`ping 10.0.2.2`).

### 🛡️ 4. Process Signals & Fault Isolation (Ring 3)
* **Kernel Stability:** Ring 3 crashes no longer trigger Kernel Panics:
  - Vector 14 (`#PF` Page Fault) $\rightarrow$ `SIGSEGV` (11)
  - Vector 13 (`#GP` General Protection) $\rightarrow$ `SIGSEGV` (11)
  - Vector 6 (`#UD` Invalid Opcode) $\rightarrow$ `SIGILL` (4)
  - Vector 0 (`#DE` Divide by Zero) $\rightarrow$ `SIGFPE` (8)
* Faulting threads are cleanly isolated, logged with crash diagnostics (`RIP`, `ErrCode`, `CR2`), and terminated. The microkernel, GUI desktop, and sibling tasks remain fully active. Test with `crash_test`.

### 🔋 5. Hardware ACPI Subsystem
* **Table Discovery:** Scans BIOS memory (`0xE0000..0xFFFFF`) for `RSDP` with checksum verification.
* **Tables Parsed:** `RSDT`, `FADT` (`PM1a_CNT`), `MADT` (LAPIC CPU Core Discovery), `HPET`, `MCFG`.
* **Power Management:** Native hardware ACPI S5 Sleep/Poweroff and 8042/ACPI hardware reset.

### 🎲 6. Hardware Random Number Generator (RNG)
* **Entropy Sources:** Checks CPUID for hardware `RDRAND` (Leaf 1, ECX 30) and `RDSEED` (Leaf 7, EBX 18).
* **PRNG Fallback:** Xorshift64* stirred with CPU cycle counter (`rdtsc`) and CMOS RTC.
* **Syscall & Tool:** Syscall 22 (`SYS_GETRANDOM`) and user command `random` / `rng` generating UUID v4 identifiers.

### 💻 7. Interactive Terminal Shell (`osh`)
* **Stylized Powerline Prompt:** `┌──(root@opencoreC)-[~]\n└─# `
* **Built-in `fastfetch`:** Integrated system information tool with custom ASCII logo and ANSI palette.
* **Log Isolation:** Daemon logs (`gui_server`, `procmgr`, `init_server`) are routed to `dmesg`, leaving the interactive terminal pristine.

---

## 🏛️ Architecture Overview

```mermaid
graph TD
    subgraph Hardware [Physical & Virtual Hardware]
        CPU["x86_64 SMP (4 Cores)"]
        FB["Linear Framebuffer (1280x800@32bpp)"]
        NIC["PCI Realtek RTL8139 Fast Ethernet"]
        PS2["PS/2 Keyboard & Mouse"]
        ACPI_HW["ACPI FADT / MADT / PM1a"]
        RNG_HW["Hardware RNG (RDRAND/RDSEED)"]
    end

    subgraph Ring0 [Rust Microkernel - Ring 0]
        SCHED["SMP Scheduler (Core Affinity & Quantum)"]
        VMM["4-Level Paging (PML4) & VMM"]
        PFA["Physical Frame Allocator (Bitmap)"]
        IPC["Fast-Path Rendezvous & Capability IPC"]
        SIG["Signal Dispatcher (SIGSEGV/SIGILL/SIGFPE)"]
        DMESG["Kernel Circular Log Ring Buffer"]
    end

    subgraph Ring3 [Isolated User Space - Ring 3]
        GUI["gui_server (LVGL Desktop Compositor) [Core 1]"]
        SH["sh (Interactive UNIX Terminal Shell) [Core 2]"]
        INIT["init_server (System Root Server) [Core 3]"]
        UART["uart_driver (16550 Serial Driver) [Core 3]"]
        PROC["procmgr (Process & Server Manager) [Core 3]"]
    end

    Hardware <--> Ring0
    Ring0 <--> Ring3
```

---

## 📁 Repository Structure

```text
opencoreC/
├── boot/
│   └── limine/                      # Limine bootloader binaries & installer
├── build/                           # Output directory for ELF binaries & disk image
├── config/
│   ├── linker.ld                    # Higher-half kernel linker script (0xffffffff80000000)
│   └── user.ld                      # Userspace Ring 3 ELF linker script (0x400000)
├── hal/                             # Hardware Abstraction Layer (PCI, 16550 UART)
├── include/
│   └── abi/
│       ├── ipc.h                    # Fast-Path IPC register layout & protocols
│       ├── syscalls.h               # System call numbers, structures, and POSIX signals
│       └── types.h                  # ABI primitive types
├── kernel/                          # Microkernel crate (Rust #![no_std])
│   ├── Cargo.toml
│   ├── asm/
│   │   ├── context.S                # Preemptive context switcher (switch_to)
│   │   └── syscall_entry.S          # Fast syscall/sysretq entry trampoline
│   └── src/
│       ├── main.rs                  # Kernel entry point & subsystem orchestrator
│       ├── arch/                    # GDT, TSS, IDT, SMP, ACPI, Syscalls
│       │   ├── acpi.rs              # RSDP, RSDT, FADT, MADT parser & poweroff
│       │   ├── gdt.rs               # Per-CPU GDT & TSS selectors
│       │   ├── idt.rs               # IDT vectors & Ring 3 signal fault handler
│       │   ├── smp.rs               # SMP multi-core AP boot & TSC_AUX per-CPU query
│       │   └── syscall.rs           # Fast-path syscall dispatcher
│       ├── drivers/                 # Microkernel drivers
│       │   ├── dmesg.rs             # Circular kernel log ring buffer
│       │   ├── keyboard.rs          # PS/2 keyboard driver
│       │   ├── mouse.rs             # PS/2 mouse driver with screen clamping
│       │   ├── rng.rs               # Hardware RNG (RDRAND / RDSEED / PRNG)
│       │   ├── serial.rs            # 16550 UART serial logger
│       │   └── timer.rs             # PIT 8254 timer (100 Hz preemptive ticks)
│       ├── ipc/                     # Capability-based synchronous rendezvous IPC
│       ├── mm/                      # Physical Frame Allocator & 4-Level Paging
│       └── sched/                   # Preemptive Multi-Core Scheduler & Threads
├── lib/
│   ├── libc/                        # Minimal freestanding C library (string, stdlib, stdio)
│   ├── libipc_cpp/                  # C++20 RAII IPC endpoints & message wrappers
│   └── lvgl/                        # LVGL v8.3 embedded graphics library
├── servers/                         # Ring 3 User-space processes
│   ├── gui_server/                  # Windows/KDE Desktop Compositor (LVGL v8.3)
│   ├── init_server/                 # System root server
│   ├── procmgr/                     # Process & server manager daemon
│   ├── sh/                          # Interactive UNIX shell (Powerline prompt & fastfetch)
│   └── uart_driver/                 # 16550 COM1 serial driver server
├── limine.conf                      # Limine bootloader configuration
├── Makefile                         # Unified build system
└── README.md                        # Documentation & project manual
```

---

## 🛠️ Build & Run Guide

### Prerequisites (Ubuntu/Debian)
```bash
sudo apt-get update
sudo apt-get install -y build-essential gcc g++ qemu-system-x86 nasm mtools xorriso
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
rustup target add x86_64-unknown-none
```

### Quick Commands
| Target | Description |
| :--- | :--- |
| `make all` | Compiles the Rust microkernel, freestanding libc, drivers, and Ring 3 servers. |
| `make image` | Builds a bootable 64 MiB hybrid FAT32 disk image (`build/opencoreC.img`) with Limine BIOS + UEFI. |
| `make gui` | **Launches QEMU in GUI mode** with the LVGL Desktop Compositor, hardware mouse, and terminal. |
| `make run` | **Launches QEMU in serial console mode** with `fastfetch` and the Powerline shell prompt. |
| `make clean` | Cleans all compiled binaries, intermediate objects, and disk images. |

---

## ⌨️ Shell Command Reference (`osh`)

Available in both the **Serial Console (`make run`)** and the **GUI Terminal Window (`make gui`)**:

| Command | Description |
| :--- | :--- |
| `fastfetch` / `neofetch` | Displays the system summary, ASCII logo, and ANSI color palette. |
| `smp` / `cpu` | Displays online physical cores, current executing CPU, and per-core scheduler ticks. |
| `acpi` | Displays ACPI RSDP status, MADT discovered cores, and FADT power management ports. |
| `random` / `rng` | Generates 16 bytes of entropy via hardware RNG and formats as a UUID v4. |
| `crash_test` | Triggers a Ring 3 null-pointer fault to verify kernel `SIGSEGV` signal handling. |
| `ps` | Lists active threads, states (`READY`, `RUNNING`, `BLOCKED`), RIP, and CPU ticks. |
| `top` | Dynamic multi-core process and CPU load monitor. |
| `mem` / `free` | Displays Physical Frame Allocator (PFA) RAM usage (Total, Used, Free). |
| `ifconfig` / `ip` | Displays Realtek RTL8139 PCI Fast Ethernet MAC, IP, and status. |
| `ping <ip>` | Transmits real ICMP Echo Ping packets over RTL8139 PCI DMA. |
| `dmesg` | Displays the circular kernel and background daemon log ring buffer. |
| `date` | Queries CMOS Real-Time Clock date and time. |
| `uptime` | Displays system uptime and PIT timer clock ticks. |
| `uname -a` | Prints operating system name, kernel version, and architecture. |
| `whoami` | Prints the active user identity (`root`). |
| `kill <tid>` | Sends a termination request to stop a specific thread by PID. |
| `calc <expr>` | Freestanding arithmetic calculator (`+`, `-`, `*`). |
| `ls` / `dir` | Lists files in the in-memory RAM disk. |
| `cat <file>` | Reads and displays text file contents. |
| `touch <file>` | Creates a new file in RAM disk. |
| `clear` | Clears the terminal screen. |
| `reboot` | Reboots the machine via ACPI / 8042 reset. |
| `poweroff` / `exit` | Powers off the computer via hardware ACPI S5 shutdown. |

---

## 📜 License

Distributed under the **MIT / Apache-2.0** dual license. See `LICENSE` for details.