Roadmap

Development plan from bare-metal boot to self-hosting OS.

Table of contents

• Sprint Overview
• Sprint 1 — Boot & Serial Output ✅
• Sprint 2 — Memory Management ✅
• Sprint 3 — Interrupts & Exceptions ✅
• Sprint 4 — Processes & Scheduler
• Sprint 5 — Capabilities & IPC
• Sprint 6 — Syscall Interface & Userspace
• Sprint 7 — Init Process & First Program
• Future Milestones
• Contributing

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Sprint Overview #

Sprint	Focus	Status	Description
1	Boot & Serial	✅ Complete	Toolchain, bootloader, serial UART, framebuffer console
2	Memory	✅ Complete	PMM bitmap allocator, VMM page tables, kernel heap
3	Interrupts	✅ Complete	GDT/TSS, IDT, ACPI/MADT, LAPIC, I/O APIC, W^X remap
4	Scheduler	🔲 Planned	Processes, threads, tickless scheduler, SMP
5	Capabilities	🔲 Planned	Capability tables, IPC channels, memory grants
6	Syscalls	🔲 Planned	SYSCALL/SYSRET, ELF loader, Ring 3 entry
7	Userspace	🔲 Planned	Init process, libmnos, first userspace driver

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Sprint 1 — Boot & Serial Output ✅ #

Get the kernel running, prove it with visible output.

• Rust nightly toolchain configuration (rust-toolchain.toml)
• Cargo workspace with kernel crate, dev/release profiles
• .cargo/config.toml — bare-metal target, kernel code-model, no SSE/AVX, build-std
• Linker script — higher-half kernel, page-aligned sections
• Limine bootloader configuration
• IRQ-safe ticket spinlock
• PhysAddr / VirtAddr newtypes with HHDM translation
• COM1 serial UART driver — 16550, 115200 baud 8N1
• CPU primitives — halt, CR2/CR3, INVLPG, RDTSC, MSRs
• Limine boot protocol interface
• kprint! / kprintln! logging macros
• Kernel panic handler
• Framebuffer text console — 8×16 bitmap font, scrolling
• Kernel entry point — 5-phase boot
• Makefile build system
• Boots in QEMU with UEFI

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Sprint 2 — Memory Management ✅ #

Teach the kernel to manage physical and virtual memory.

• Physical Memory Manager — bitmap allocator (alloc, free, zeroed, contiguous)
• VMM page table infrastructure (map, unmap, translate)
• Kernel Heap — linked-list allocator with coalescing, enables alloc crate
• Linker script fix — .got section handling
• Kernel higher-half remap (completed in Sprint 3)
• W^X enforcement via remap (completed in Sprint 3)

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Sprint 3 — Interrupts & Exceptions ✅ #

Handle CPU exceptions and hardware interrupts safely.

• GDT — kernel/user segments, TSS with IST1 guard page, SYSRET layout
• IDT — 15 exception handlers + 16 IRQ stubs + spurious @255 (swapgs + SysV ABI)
• ACPI — XSDT-first MADT parser, Limine rev3 HHDM gap fix
• LAPIC — CPUID 0x15 + PIT calibration, one-shot mode, spurious handler
• I/O APIC — MADT parsing, IRQ routing, legacy PIC disable
• W^X remap — in-place page table update (.text=R+X, .rodata=R, .data/.bss=R+W+NX)

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Sprint 4 — Processes & Scheduler 🔲 #

Run multiple threads of execution, share the CPU fairly.

• Process / Thread structures — address space, capability table, state machine
• Context switching — register save/restore, CR3 switch, FPU lazy state
• Tickless scheduler — per-core run queues, work-stealing, idle thread
• SMP initialization — INIT/SIPI, per-core GDT/IDT/TSS/LAPIC

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Sprint 5 — Capabilities & IPC 🔲 #

The security model — unforgeable tokens and message passing.

• Capability table — per-process, slot-based, typed with rights bitmask
• Capability operations — create, delete, transfer (rights reduction), revoke
• Synchronous IPC — send/receive on capability-protected endpoints
• Call/Reply RPC — synchronous request-response pattern
• Notifications — lightweight non-blocking event signaling
• Zero-copy memory grants — share physical pages via capabilities

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Sprint 6 — Syscall Interface & Userspace 🔲 #

Cross the Ring 0/Ring 3 boundary.

• SYSCALL/SYSRET — MSR configuration, entry point, register save/restore
• Syscall dispatch — ~22 syscalls indexed by RAX
• ELF loader — parse ELF64, map segments, set up user stack
• Ring 3 entry — user page tables, SYSRET to entry point

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Sprint 7 — Init Process & First Program 🔲 #

Life outside the kernel.

• Init process — capability receiver, service spawner, name directory
• Userspace library (libmnos) — syscall wrappers, IPC helpers, allocator
• First userspace driver — serial console via IRQ capability + IPC

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Future Milestones #

These features are planned for after Sprint 7 completes the core OS:

Milestone	Description
VFS Service	Virtual filesystem abstraction in userspace
Initramfs	In-memory tar filesystem for boot-time binaries
Disk Driver	AHCI/NVMe driver in userspace
Filesystem	ext2 or FAT32 implementation as userspace service
Networking	TCP/IP stack as a userspace service
Shell	Basic interactive command-line shell
USB HID	Keyboard and mouse drivers
GPU Driver	Intel HD 405 framebuffer driver
Compositor	Window manager / display server
Rust std Port	Port Rust's standard library to MinimalOS
Self-hosting	Compile MinimalOS on MinimalOS

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Contributing #

Contributions are welcome! The project is structured around sprints — each sprint focuses on a self-contained subsystem.

How to Contribute

1. Check the current sprint's open items above
2. Read the relevant subsystem documentation
3. Fork the repository and create a feature branch
4. Implement your changes with tests where applicable
5. Submit a pull request

Development Guidelines

• Rust edition 2024 with no_std — no standard library
• No unsafe without justification — document why each unsafe block is sound
• Comments explain WHY, not what — assume the reader knows Rust
• One commit per logical change — granular, descriptive commit messages
• Test in QEMU — make run before submitting