From OSDev Wiki
Jump to: navigation, search


User interface prototype
Developed by:Oleg Petrenko
Task Model:Preemptive multitasking
Language(s):C++, NASM, Hexa

GreenteaOS is a 64-bit desktop OS for x86-64. Aims to run .exe files natively and become open-source Windows alternative. Follows own non-NT/non-UNIX monolithic kernel design. Currently in the pre-alpha state.



Started as a ReactOS fork in 2016, later in 2018 reconsidered to create own kernel from scratch. Competition should improve development speed of both projects, due to more people involved with different points of view.

Design and Features

GreenteaOS features own kernel Tofita: a non-portable, strictly x86-64 desktop-oriented monolithic design with UEFI bootloader.

GreenteaFS is also considered to be used as a primary file system. With hybrid approach of CoW and non-CoW structure to achieve maximal performance on consumer desktop PCs (in comparison to most other fs's designed for server use). Sources of GreenteaFS are not yet available due to active experimentation. Somewhat influenced by TFS of Redox. Intended to be very compatible with NTFS in API terms (like streams support and unicode file names).

GUI is, of course, intended to be hardware accelerated in the future, with GPU drivers as parts of the kernel (i.e. non-userspace). Only support for AMD GCN1+ and DX12-capable Intel is planned, with Nvidia being still closed source and excluded from support. Support for the Windows NT GPU drivers is not planned.

Safety to be provided with user (personal) space and apps isolation. Think of a portable user folders and apps in wine-prefix manner.

Kernel will be rewritten in Hexa language when that will be mature enough.

Critical reception

GreenteaOS is very controversial in the eyes of ReactOS community. This is a hard topic, and resulted in breach of any connections between both projects. Still, there is no intention from GreenteaOS project to spread any negativity towards usefulness or anything about ReactOS.

Developers believe that having more options, than solely Wine and ReactOS, will attract more attention from IT community as a whole and to the problem of Windows not delivering high quality software (and, you know, all that telemetry stuff and annoying updates). BTW Windows 7 was recently updated to silently break on pre-SSE2 computers.


You may found sources at GitHub. Notably Tofita kernel ones.

Personal tools