SUB-OS: Modular Monolithic Linux-Compatible Operating System

   _____ _    _ ____          ____   _____ 
  / ____| |  | |  _ \        / __ \ / ____|
 | (___ | |  | | |_) |______| |  | | (___  
  \___ \| |  | |  _ <|______| |  | |\___ \ 
  ____) | |__| | |_) |      | |__| |____) |
 |_____/ \____/|____/        \____/|_____/ 

SUB-OS is a multi-architecture, production-grade modular monolithic operating system kernel engineered in C, C++17, Assembly, freestanding bare-metal Rust (no_std), and the custom SUB Language (.sb). Built for high performance, memory safety, modularity, and Unix/Linux compatibility, SUB-OS supports 64-bit x86 (x86_64), 64-bit ARM (aarch64), and 32-bit ARM (armv8i / AArch32) targets.

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🌟 Key Architecture & Capabilities

• 🧶 Weave Scheduler & Real Context Switching (kernel/sched.c, arch/*/cpu/switch.*):
  • Genuine multitasking, not a state relabel: sub_ctx_switch() is per-architecture assembly (x86_64/aarch64/armv8i) that saves and restores the callee-saved register set plus flags on each thread's own kernel stack, with a first-run trampoline that launches a freshly forged thread frame.
  • Tiered rotation with behavioural weaving: runnable threads thread through WEAVE_NLANES priority lanes; the dispatcher always pulls the lowest non-empty lane round-robin. A thread that yields voluntarily is woven up toward low latency, one that burns its whole quantum and is preempted is woven down toward throughput — the lane floats on observed behaviour, not a static nice value.
  • Boot-time self-test: before hardware interrupts come up, the Weave scheduler drives three cooperative kernel threads to completion on separate stacks (verified under QEMU: correct round-robin interleave, clean return to the boot thread) — proof the switch is real.
• 🧵 Kernel Concurrency Core (kernel/wait.c, kernel/futex.c, kernel/rcu.c):
  • Wait Queues & Completions: Sleeper parking with timed waits, one-shot completion barriers, and a static entry pool so a blocking path never re-enters the allocator (waitinfo).
  • Futex Hash Table: 32 buckets with value re-check on the slow path, requeue support, and an fmutex_t sleeping mutex built on the uncontended-fastpath protocol (futexinfo).
  • Tiny RCU: Lock-free readers with nesting depth tracking, deferred call_rcu/kfree_rcu callbacks, grace-period accounting, and rcu_assign_pointer/rcu_dereference publish barriers (rcuinfo).
• 🧱 Core Data Structures (lib/rbtree.c, lib/kfifo.c, lib/hashtable.c):
  • Red-Black Tree: Linux-compatible parent-pointer rbtree with full insert/erase rebalancing, forward and reverse in-order iteration, and a black-height invariant validator.
  • kfifo Ring Buffer: Power-of-two byte ring with free-running indices, so the wrap path costs one mask instead of a branch per byte.
  • Hash Table: Separately-chained FNV-1a table with string or u64 keys and rehash-on-growth at a 3/4 load factor.
• 💾 Block Page Cache (mm/page_cache.c):
  • Write-back cache of 4 KB pages keyed by (device, page index), indexed through the kernel hash table.
  • CLOCK second-chance eviction with dirty write-back, pinning, per-device flush and invalidate, and live hit-rate telemetry (pagecache).
• 🧪 In-Kernel Test Harness (kernel/ktest.c):
  • KUnit-style suites with assertion macros, per-case pass/fail reporting and timing.
  • 6 built-in suites, 21 cases, 735 assertions covering rbtree, kfifo, hashtable, RCU, futex, wait queues, page cache and libcore — runnable from the shell (ktest) or the desktop KTest Runner.
• 🎨 Boot Logo & Splash Screen (init/bootlogo.c, scripts/mklogo.py):
  • Two presentations of one artwork: an ASCII rendition on the text console and serial line from the first moments of boot, then the real bitmap as a graphical splash once the video driver is up at step [5/14].
  • 4-bit palette-indexed asset: 160x160 pixels in 12.5 KB rather than 100 KB, with a transparency mask so the mark composites onto the gradient instead of a flat rectangle.
  • Animated progress bar tied to the real boot stages, held for a minimum duration (splashtime=<ms>) so a sub-second boot still shows it; nosplash, nogui or text skip it.
  • Regenerable: python3 scripts/mklogo.py path/to/logo.png rewrites init/logo_data.c from source artwork.
• 🔤 Shared 8x8 Console Font (lib/font8x8.c): one glyph table behind the framebuffer console, the 2D canvas rasterizer and the desktop compositor, replacing three divergent private copies.
• 🖵 Framebuffer Console (drivers/video/fbcon.c):
  • Once the VBE adapter is in graphics mode the VGA text buffer stops being scanned out, so anything printed afterwards is invisible on the display even though it still reaches serial. fbcon renders the console into the framebuffer instead, the way Linux fbcon does.
  • VT100 subset: SGR colours, cursor addressing (H/f), relative moves, erase-display and erase-line, save/restore — enough for full-screen curses-style programs such as the nano editor to render correctly.
  • Presents a fixed 80x25 grid (matching TTY_WIDTH/TTY_HEIGHT, which the userland assumes) with the glyph cell scaled to fill whatever resolution is active.
  • The TTY driver dispatches tty_write, tty_clear and tty_set_cursor to it, so leaving the desktop with Esc drops to a working console inside the emulator, not just on the host serial line.
• 🖥️ SUB-OS Graphical Desktop Environment (gui/):
  • SUB-WM Compositor: 800x600 TrueColor double-buffered window manager with drag, corner resize, minimize/maximize/restore, edge snapping (left/right/maximize), tile and cascade layouts, and z-ordered painter's-algorithm compositing.
  • SUB-WT Widget Toolkit (gui/gui_widgets.c): Immediate-mode controls -- buttons, labels, checkboxes, radios, sliders, list boxes, text fields, tab bars, scrollbars, progress bars, sparklines and badges -- so an app rebuilds its interface from state each frame instead of maintaining a retained widget tree.
  • Icon Set (gui/gui_icons.c): 14 hand-drawn 16x16 palette-indexed glyphs, integer-scalable and tintable, driving the desktop grid, start menu and window chrome.
  • Modal Dialog Layer (gui/gui_dialog.c): Info, warning, error and confirm dialogs that dim the desktop and take exclusive input, with word-wrapped messages and callback results.
  • Desktop Shell (gui/gui_desktop.c): Gradient wallpaper with grid overlay, launcher icon grid, start menu, right-click context menu (tile / cascade / toggle grid), and a taskbar with per-window buttons, live CPU trace, memory badge and RTC clock.
  • Terminal Emulator (gui/gui_terminal.c): dispatches to the real LazyBox applet table and the shared shell builtins, capturing each command's printk output through a console sink. ANSI colours are translated per line, CP437 box and block characters fall back to ASCII, and there is 256 lines of scrollback plus command history.
  • Applications: Terminal, File Explorer, System Monitor, Task Manager, Kernel Log viewer (live dmesg with severity colouring and scrollback), KTest Runner (drives the in-kernel suites and reports pass/fail), Text Editor, Calculator, Paint Studio, Clock & Calendar, Settings and About.
  • Keyboard Shortcuts: F5 cycle focus, F6 cascade, F7 tile, F8 maximize, F9 minimize, Esc exit to the kernel TTY.
• ⚡ Freestanding C++17 OOP Kernel Engine (kernel/cpp/):
  • Bare-Metal C++ Runtime: operator new/delete, sized deallocation, placement new, pure virtual handlers (__cxa_pure_virtual), and .init_array global constructor dispatcher.
  • Modern Generic Containers: Pure freestanding Vector<T>, UniquePtr<T> (with polymorphic converting constructors and custom deleters), dynamic String, and move semantics (kernel::move, kernel::forward).
  • Object-Oriented Device Driver Model: Abstract Device base class with BlockDevice, CharDevice, VirtualRamDiskDevice (512B sector emulator), and VirtualNull/VirtualZero concrete classes managed by the DeviceManager singleton.
  • C++ Microbenchmark Engine: Validates zero-overhead abstractions, virtual method dynamic dispatch latency across 500,000 iterations, and dynamic container throughput.
  • Interactive C++ Commands: cppinfo (Kernel telemetry), cppdevs (OOP device tree), cppbench (Microbenchmarks), and cpptest (Polymorphic dispatch verifier).
• 🐍 Interactive In-Kernel Snake Game (userland/lazybox/snake.c):
  • Full-featured ANSI terminal game featuring real-time keyboard control (WASD and Arrow keys), dynamic food generation, score counter, body growth, wall/self collision detection, and autonomous simulation mode (snake --demo).
• 🔮 SUB Programming Language Kernel Signature & In-Kernel VM (sub/ & kernel/sub/):
  • Native .sb Kernel Modules: Key subsystems written directly in the custom SUB language:
    • sub/signature.sb: Kernel identity, OS signature, and author credits.
    • sub/power_governor.sb: Dynamic CPU P-state thermal scaling and frequency/voltage calculations.
    • sub/benchmark.sb: Recursive Fibonacci and integer matrix benchmark algorithms.
    • sub/easter_egg.sb: Interactive kernel quotes and easter eggs.
  • In-Kernel SUB Virtual Machine & AST Interpreter (subi): Run .sb scripts or inline expressions live from the shell (subi file.sb or subi -e "var x=10; print(x*2)").
• 🦀 "Rust for SUB-OS" Memory-Safe Kernel Layer (rust/src/):
  • Freestanding Bare-Metal Rust: Compiled with rustc 1.75+ in pure no_std mode with static FFI bindings.
  • Memory-Safe Cryptography: RFC-8439 ChaCha20-Poly1305 AEAD authenticated cipher, CSPRNG entropy source, FIPS-202 SHA3-256 (Keccak-f[1600]), FIPS-197 AES-128, and RFC-4648 Base64 codec.
  • Zero-Copy ELF Binary Parser: Header and segment inspector validating ELF-64/32 binaries and architectures (readelf).
  • Memory Fragmentation & Buddy Telemetry: Order 0-10 buddy allocator tracking and external fragmentation indexes (buddyinfo).
  • Storage & Disk Parsing: Memory-safe MBR and GUID Partition Table (GPT) header and partition decoder (fdisk).
  • Fast VFS Directory Cache (dcache): 64-entry LRU path hash table for single-cycle file and directory lookups.
  • Kernel Health Watchdog & Heartbeat Monitor: Subsystem sanity checker and anomaly detector.
  • Zero-Copy JSON Tokenizer: High-speed JSON key-value query engine for kernel configuration and REST API parsing.
  • NetFilter Packet Evaluator: Stateful firewall rule matcher and packet counter.
• 🎯 Multi-Architecture HAL:
  • x86_64 (AMD64 / Intel 64): Custom 2-stage MBR bootloader, E820 BIOS memory mapping, 4-level PML4 48-bit paging, GDT, 256-entry IDT, 8259 PIC, 8254 PIT timer, Hardware FPU/SSE (CR4.OSFXSR).
  • aarch64 (ARMv8-A 64-Bit): Exception levels (EL1), 16-entry vector table, ARM Generic Interrupt Controller (GICv2), ARM Generic Arch Timer (100 Hz), Stage-1 39-bit VA MMU, PL011 UART.
  • armv8i (ARM32 / AArch32): Banked exception mode stacks (IRQ, ABT, UND, SVC), VMSAv7 1MB Section MMU, GICv2 distributor, CP15 Generic Timer, VFP/NEON FPU, PL011 UART.
• 🎛️ Linux-Style Kconfig TUI Configurator (make configure):
  • Full interactive lxdialog GUI interface (Royal Blue backdrop, floating modal windows, drop shadows, and menu hierarchy).
  • Dynamic Kbuild-style selective compilation based on .config and include/config/autoconf.h.
• 📁 Storage & Filesystem Layer:
  • FAT32 (VFAT) storage driver with directory traversal and /mnt/fat32 auto-mounting.
  • Second Extended (EXT2) Linux filesystem driver.
  • Virtual File System (VFS): POSIX open, read, write, close, seek, mount interface.
  • Synthetic DevFS (/dev), ProcFS (/proc), and Sysfs KObject Hierarchy (/sys).
  • Dynamic in-memory RAM disk (/dev/ram0).
• 🖧 Hardware Device Drivers:
  • Storage Controllers: NVMe PCIe SSD, AHCI SATA 6Gb/s, IDE/ATA Hard Disks, VirtIO-Block.
  • Network Adapters: Intel 82540EM Gigabit Ethernet, Realtek RTL8139 Fast Ethernet, VirtIO-Net 10GbE.
  • Multimedia & Display: Bochs/VBE dynamic resolution video adapter, 2D TrueColor Canvas Rasterizer, Intel High Definition Audio (Azalia HDA), AC'97 sound codec, Formant TTS synthesizer, 8-Bit Melody player.
  • Bus & Sensors: PCI bus enumerator, USB 3.0 Extensible Host Controller (xHCI), HWMON CPU temperature and fan tachometer sensors, VirtIO-RNG hardware entropy generator, Unix98 PTY subsystem.
• 🌐 Networking, Firewalls & Daemons:
  • Full L2–L4 IPv4 protocol stack with dynamic ARP, ICMP Echo (ping), UDP, and full 3-way handshake TCP state machine.
  • NetFilter stateful packet inspection firewall (iptables).
  • Built-in OpenSSH 2.0 Daemon (sshd) on port 2222.
  • Built-in Micro HTTP REST API Server (httpd) on port 8080.
• 🔒 Kernel Security & Async Engine:
  • Linux Security Module (LSM) enforcing POSIX capabilities and DAC.
  • X.509 Cryptographic Keyring with signature verification.
  • In-Kernel eBPF Register Virtual Machine and verifier.
  • io_uring lockless asynchronous Submission/Completion ring buffers.
  • Weave tiered-rotation scheduler with real per-arch context switching and spinlock synchronization (see the Weave Scheduler entry above).
  • Systemd-style unit manager (systemctl), cron background scheduler (crond), and RFC 5424 Syslog engine.
• 🧰 LazyBox Userland Suite (85+ Linux, Rust, C++ & SUB-Lang Applets):
  • Interactive shell with history, quote-aware tokenization, tab autocompletion, ANSI cursor editing, and script runner (sh).
  • GNU-compatible Nano visual text editor.
  • Text Processing Suite (userland/lazybox/coreutils.c): sort, uniq, cut, tr, rev, tac, nl, seq, diff, xxd, du, factor, sum and truncate, all reading through the VFS and handling the zero-length synthetic nodes procfs and sysfs expose.
  • Kernel Diagnostics: ktest, rcuinfo, futexinfo, waitinfo and pagecache.
  • Full utilities: ls, cat, touch, mkdir, rm, cp, pwd, cd, tree, find, wc, head, tail, stat, df, mkfs.vfat, hexdump, neofetch, uname, free, uptime, top, ps, pstree, kill, dmesg, netstat, ifconfig, ping, traceroute, curl, ssh, tts, alsamixer, sensors, rustinfo, chacha20, sha3sum, base64, cryptobench, fdisk, rfilter, dcache, watchdog, jsonquery, subinfo, subi, subpower, subbench, subquote, cppinfo, cpptest, snake, and more.

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🏛️ Comprehensive Architecture

+------------------------------------------------------------------------------------+
|                             USERLAND & SYSTEM SUITE                                |
|  Interactive Shell | GNU Nano | Snake Game | Script Runner (sh) | LazyBox (85+ Apps)|
|  Micro HTTP Server | SSH 2.0 Daemon | Service Manager (systemctl) | Syslog Engine  |
+------------------------------------------------------------------------------------+
|                       SUB LANGUAGE IN-KERNEL VM & MODULES                          |
|  subi Interpreter | OS Signature | CPU Power Governor | Recursive Math Benchmark   |
+------------------------------------------------------------------------------------+
|                      FREESTANDING C++17 OOP KERNEL ENGINE                          |
|  Virtual Method Dispatch | RAII | Polymorphism | Telemetry Classes | Templates     |
+------------------------------------------------------------------------------------+
|                       RUST-FOR-SUB-OS MEMORY-SAFE SUBSYSTEM                        |
|  ChaCha20 CSPRNG | SHA3-256 Keccak | AES-128 | Base64 | GPT/MBR | NetFilter Matcher|
|  VFS DCache Table | Kernel Health Watchdog | Zero-Copy JSON | Hardware Sensors     |
+------------------------------------------------------------------------------------+
|                         VIRTUAL FILE SYSTEM LAYER (VFS)                            |
|  vfs_namei | RAMFS (/) | /dev (devfs) | /proc (procfs) | /sys (sysfs) | FAT32 | ext2|
+------------------------------------------------------------------------------------+
|         NAMESPACES, INTER-PROCESS COMMUNICATION & ASYNC I/O ENGINE                 |
|  PID/UTS Isolation | Pipes | Message Queues | Shared Memory | Semaphores | io_uring|
+------------------------------------------------------------------------------------+
|                   CORE KERNEL SERVICES, SECURITY & TRACING                         |
|  Preemptive Scheduler | Fast Syscalls | Dynamic Modules | eBPF Virtual Machine     |
|  LSM POSIX Capabilities | X.509 Keyring | Workqueues | Telemetry & Kernel Tracer   |
+------------------------------------------------------------------------------------+
|               NETWORKING, NETFILTER FIREWALL & SOUND ARCHITECTURE                  |
|  Ethernet | ARP | IPv4 | ICMP | UDP | TCP | DHCP | DNS | Sockets | NetFilter FW   |
|  Embedded HTTP Server (8080) | SSH Server (2222) | Intel HDA | AC'97 | Formant TTS |
+------------------------------------------------------------------------------------+
|                             DEVICE DRIVER TREE                                     |
|  NVMe PCIe SSD | AHCI SATA | ATA IDE | VirtIO-Blk | Ramdisk (/dev/ram0)            |
|  Intel E1000 NIC | RTL8139 NIC | VirtIO-Net | USB 3.0 xHCI | HWMON Sensors         |
|  Bochs VBE Display | 2D Canvas | VGA / TTY1-4 | 16550 Serial | PL011 UART          |
+------------------------------------------------------------------------------------+
|                        HARDWARE ABSTRACTION LAYER (HAL)                            |
|  x86_64 (AMD64/PML4) | aarch64 (ARMv8-A/GICv2/MMU) | armv8i (AArch32/Section MMU)  |
+------------------------------------------------------------------------------------+

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🚀 Quick Start Guide

1. Prerequisites

Install the standard build essentials, cross-compilers, and Rust toolchain:

# Ubuntu / Debian
sudo apt update
sudo apt install build-essential g++ nasm qemu-system-x86 qemu-system-arm \
                 gcc-aarch64-linux-gnu binutils-aarch64-linux-gnu \
                 gcc-arm-linux-gnueabihf binutils-arm-linux-gnueabihf \
                 rustc cargo dialog python3

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2. Linux-Style TUI Configuration

Launch the interactive Kconfig configurator:

make configure

(Also available via make menuconfig)

Fast Architecture Presets:

make x86_64_defconfig    # Configure for x86_64 (Intel / AMD 64-Bit)
make aarch64_defconfig   # Configure for 64-bit ARM (Cortex-A57)
make armv8i_defconfig    # Configure for 32-bit ARM (Cortex-A15)

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3. Compilation & Live Emulation

Target: x86_64 (Default)

make x86_64_defconfig
make
make run

Port forwardings automatically configured in QEMU:

• SSH Server: ssh root@localhost -p 2222 (Password: root)
• HTTP REST API: http://localhost:8080/api/status

Target: aarch64 (ARMv8-A 64-Bit)

make aarch64_defconfig
make ARCH=aarch64
make run ARCH=aarch64

Target: armv8i (ARM32 / AArch32)

make armv8i_defconfig
make ARCH=armv8i
make run ARCH=armv8i

Graphical Desktop Environment

SUB-OS boots straight into the desktop. Pass nogui, text, emergency or single on the kernel command line to go directly to the kernel TTY instead; from inside the desktop, Esc (or Start -> Exit to Kernel TTY) drops to the same shell.

The display mode is set with video=WIDTHxHEIGHT on the kernel command line (default 1280x720, 16:9). Both the desktop and the framebuffer console adapt to whatever mode is active.

make run-gui         # Windowed, aspect-preserving scaling
make run-fullscreen  # Fullscreen without stretching
make run-vnc         # Headless: VNC server on localhost:5900

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🧰 LazyBox Command Matrix (85+ Utilities)

Category	Commands Included
Core & Shell	lazybox, sh, echo, env, export, whoami, id, date, cal, jsonquery, subi
Filesystem & Search	nano, ls, cat, touch, mkdir, rm, cp, pwd, cd, tree, find, wc, head, tail, stat, df, mkfs.vfat, grep, hexdump, dcache
Networking & Routing	ifconfig, ping, traceroute, arp, dhclient, nslookup, dnscache, netstat, iptables, rfilter, httpd, sshd, curl, wget, ssh, e1000e
Hardware & Storage	lspci, lsdev, lsblk, fdisk, hdparm, sensors, speaker, beep, mouse, alsamixer, tts, virtinfo, gpuinfo, cpufreq
Security & Cryptography	su, passwd, useradd, certcheck, capsh, ipcs, chacha20, sha3sum, base64, aead, cryptobench
SUB Language & System	subinfo, subpower, subbench, subquote, pstree, kill, shm, readelf, buddyinfo, tscinfo, systemctl, service, crontab, logger, logread, watchdog, rustinfo, cppinfo, cpptest, cppdevs, cppbench
Entertainment & Games	snake, matrix, calc, vtart
Kernel & Tracing	lsmod, insmod, rmmod, slabinfo, trace, unshare, io_uring_test
Diagnostics & Metrics	neofetch, uname, free, uptime, top, htop, ps, dmesg, vmstat, iostat
System Control & GUI	clear, help, sleep, reboot, shutdown, poweroff, tty, startx, gui, desktop

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📦 Official Release

Download precompiled kernel binaries and bootable disk images from GitHub: 👉 SUB-OS v0.0.1-beta Release

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📄 License

SUB-OS is distributed under the open-source MIT License. See LICENSE for details.