Architecture Overview

MerlionOS is a hybrid kernel with 330 modules across 121,000+ lines of Rust, supporting four CPU architectures. It runs primarily as a monolithic kernel in ring 0, with an optional microkernel mode (v45) for service isolation and hot-restart.

Layer Diagram

┌───────────────────────────────────────────────┐
│             User Space (Ring 3)               │
│  ELF binaries, libc, /bin programs            │
│  Dynamic linker, WASI runtime                 │
├───────────────────────────────────────────────┤
│           Kernel Shell (450+ cmds)            │
│  NL interface, AI agents, scripting engine    │
├───────────────────────────────────────────────┤
│             Kernel Subsystems                 │
│  ┌───────────┐ ┌───────────┐ ┌─────────────┐ │
│  │ Scheduler │ │    VFS    │ │  Security   │ │
│  │ preempt + │ │ ext4/tmp/ │ │ caps/seccomp│ │
│  │ RT (EDF)  │ │ proc/sys  │ │ ACLs/audit  │ │
│  └───────────┘ └───────────┘ └─────────────┘ │
│  ┌───────────┐ ┌───────────┐ ┌─────────────┐ │
│  │  Memory   │ │  Drivers  │ │   Network   │ │
│  │ slab/page │ │PCI/ACPI/  │ │IPv4/v6/TCP/ │ │
│  │ demand pg │ │virtio/GPU │ │UDP/HTTPS/TLS│ │
│  └───────────┘ └───────────┘ └─────────────┘ │
│  ┌───────────┐ ┌───────────┐ ┌─────────────┐ │
│  │    AI     │ │  Audio    │ │    GUI      │ │
│  │ inference │ │ mixer/WAV │ │  widgets/   │ │
│  │ ML/vector │ │ synth/MIDI│ │  themes     │ │
│  └───────────┘ └───────────┘ └─────────────┘ │
├───────────────────────────────────────────────┤
│            Hardware Abstraction               │
│  x86_64:     GDT, IDT, APIC, PIT, VGA, FB   │
│  aarch64:    GIC, Generic Timer, PL011 UART  │
│  riscv64:    PLIC, CLINT Timer, SBI console  │
│  loongarch64: EIOINTC, Stable Timer, UART    │
│  SMP: up to 16 CPUs, per-CPU state           │
│  Power: P/C-states, thermal, battery         │
└───────────────────────────────────────────────┘

Supported Architectures

MerlionOS runs on four CPU architectures with a shared kernel core and per-architecture HAL (Hardware Abstraction Layer):

Architecture	Target Triple	Boot Method	Interrupt Controller	Timer	UART
x86_64	x86_64-unknown-none	BIOS (bootloader 0.9) / UEFI (Limine)	PIC / APIC	PIT / HPET	16550 COM1
aarch64	aarch64-unknown-none	Raspberry Pi firmware	GIC (Generic Interrupt Controller)	ARM Generic Timer	PL011
riscv64	riscv64gc-unknown-none-elf	OpenSBI	PLIC	CLINT	SBI console
loongarch64	loongarch64-unknown-none	UEFI	EIOINTC	Stable Counter	16550-compatible

The architecture-independent kernel subsystems (scheduler, VFS, networking, AI, etc.) are shared across all targets. Each architecture provides its own arch_* module implementing the HAL traits for interrupts, memory management, timer, and console I/O.

Syscall ABI

User programs communicate with the kernel via int 0x80. The kernel provides 15 syscalls:

#	Name	Args	Description
0	write	rdi=buf, rsi=len	Write to file descriptor
1	exit	rdi=code	Terminate process
2	yield	—	Yield to scheduler
3	getpid	—	Get current PID
4	sleep	rdi=ticks	Sleep for N ticks
5	send	rdi=chan, rsi=byte	Send to IPC channel
6	recv	rdi=chan	Receive from IPC channel
7	open	rdi=path, rsi=flags	Open a file descriptor
8	read	rdi=fd, rsi=buf, rdx=len	Read from file descriptor
9	close	rdi=fd	Close a file descriptor
10	fork	—	Fork current process (COW)
11	exec	rdi=path	Execute ELF binary
12	mmap	rdi=addr, rsi=len	Map memory pages
13	ioctl	rdi=fd, rsi=cmd	Device control
14	socket	rdi=domain, rsi=type	Create network socket

Virtual Filesystem

The VFS layer supports six filesystem backends:

/
├── bin/            # user-space programs (ELF)
├── dev/
│   ├── null        # discard sink
│   ├── serial      # COM1 serial port
│   ├── fb0         # framebuffer device
│   └── audio       # audio mixer
├── proc/           # procfs — 28 entries
│   ├── uptime      # system uptime
│   ├── meminfo     # heap statistics
│   ├── tasks       # running task list
│   ├── cpuinfo     # CPU topology & features
│   ├── net/        # network statistics
│   └── ...         # mounts, modules, interrupts, etc.
├── sys/            # sysfs — device model
│   ├── devices/    # device hierarchy
│   ├── bus/        # bus types (PCI, virtio)
│   └── power/      # power management
├── mnt/            # ext4 / MF16 block devices
└── tmp/            # tmpfs — writable in-memory files

Supported filesystems: MF16 (FAT16-like), ext4 (extents, journaling, htree), tmpfs, procfs, sysfs, devfs.

Security Model

MerlionOS implements defense in depth:

• Capabilities — fine-grained privilege control per process
• Seccomp — syscall filtering policies
• POSIX ACLs — per-user/group access control on filesystem objects
• Audit log — structured security event logging with remote syslog
• Container isolation — namespaces, veth networking, resource limits

AI Subsystem

The kernel includes a built-in AI platform:

• Neural network inference — INT32 arithmetic, no floating point required
• ML training — linear regression, decision trees, KNN
• Vector store — semantic search with cosine similarity
• Workflow engine — task orchestration and scheduling
• Self-evolution — code analysis, patch generation, self-healing

Microkernel Mode

Optional microkernel mode (v45) provides:

• Service isolation in separate address spaces
• Message-passing IPC between services
• Hot-restart of failed services without full reboot
• Fault containment boundaries

Network Stack

Full network stack with:

• IPv4 + IPv6 dual stack with ARP, ICMP, NDP
• TCP with congestion control (Reno, Cubic, BBR)
• UDP, DNS client/server with zone management
• Application protocols — HTTP/HTTPS, SSH, SCP, MQTT (QoS), WebSocket
• TLS — certificate validation, reverse proxy
• Container networking — veth pairs, bridge, network namespaces