RainOSVersion: 1.1.0 Last patch (Not listed): Added 64-bits and Uefi Support.
RainOS is an educational operating system kernel built for experimentation, low-level learning, and controlled system design.
It is not meant to compete with existing operating systems.
It exists to understand them.
Philosophy: Just build what you enjoy.
RainOS is a space for curiosity, architecture exploration, and system design without unnecessary abstraction layers.
RainOS is designed as:
- A learning environment for kernel development
- A playground for framebuffer graphics experimentation
- A testing ground for boot, memory management, and architecture transitions
- A controlled platform for building UI systems directly over hardware abstractions
The focus is clarity, simplicity, and intentional system design.
RainOS uses:
- GRUB (Multiboot2)
- Framebuffer-based graphics
- 64-bit long mode
- Custom memory paging setup
- QEMU + OVMF for development
RainOS is capable of running in UEFI environments.
However, at the current stage, it is primarily executed using CSM (Compatibility Support Module) due to ongoing driver and low-level initialization limitations.
UEFI-native execution is supported in virtualized environments, but real hardware UEFI boot will remain partially limited until hardware driver layers are fully stabilized.
RainOS operates directly on a framebuffer provided by the bootloader. All rendering is done without external graphical stacks.
There is no dependency on external GUI frameworks. All graphics are handled internally.
RFTK is the complete framebuffer abstraction layer of RainOS.
It is responsible for:
- Pixel management
- Drawing primitives
- Font rendering
- Memory-safe framebuffer access
- Color manipulation
- Surface abstraction
RFTK attempts to reduce the complexity of low-level framebuffer handling while maintaining full control over memory and rendering logic.
It exists to make framebuffer-based kernel development practical and structured.
RWTK is implemented directly inside the kernel.
It is not a userspace library. It operates fully in kernel space using RFTK as its backend.
RWTK provides:
- Window abstraction
- Basic UI components
- Internal application structure
- Event routing
- Desktop-like behavior
The goal of RWTK is to make application creation inside RainOS easier without sacrificing architectural transparency.
It acts as a lightweight alternative to traditional GUI systems, built specifically for RainOS.
- Freestanding 64-bit kernel
- Custom GDT and paging setup
- Manual long mode transition
- Identity-mapped memory regions
- Interrupt handling (IDT + ISR)
- Basic driver layer (keyboard, mouse, RTC)
- Framebuffer graphical environment
Everything is built with direct hardware awareness in mind.
Recommended environment:
- Linux (Ubuntu/Debian-based recommended)
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- Arch Linux having much problems with QEMU and OVMF (v1.2.0)
- NASM
- GCC (freestanding mode)
- GRUB tools
- QEMU
- OVMF for UEFI testing
Build:
make
Run (UEFI + KVM recommended):
make run-cpu # Runs in QEMU using OVMF (UEFI firmware emulation), not your machine's UEFI.
RainOS is not about feature count.
It is about:
- Understanding the boot process
- Controlling memory explicitly
- Designing UI from scratch
- Experimenting with system architecture
- Learning by building
It favors intention over complexity.
It favors clarity over convenience.
It exists because building systems is enjoyable.
RainOS is experimental and educational.
It is under active development. APIs and internal structures may change.
It is a learning system first. A product never.
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Patches App
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Settings App
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Showcase App
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Debug App
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Improved Cursor
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Improved Icons
Made by: htcdevk0,Maxmoita