reactos/reactos
A free Windows-compatible Operating System
What's novel
A free Windows-compatible Operating System
Code Analysis
7 files read · 3 roundsA complete open-source reimplementation of the Windows NT operating system kernel, HAL, user-mode subsystems, drivers, and application compatibility layer, enabling Windows NT applications and drivers to run on non-Microsoft hardware.
Strengths
Genuinely deep kernel implementation with real algorithms for thread scheduling (priority-based with SMP affinity, IPI, quantum management), virtual memory section management with PE format parsing, object manager handle tables with multi-level indexing, executive resources with priority boosting, and APC delivery — all with proper locking, IRQL management, and reference counting. The codebase follows Windows NT kernel conventions precisely, with consistent naming (Ki/Ke/Ex/Mm/Ob/Ps/Se prefixes)
Weaknesses
Some SMP features are explicitly marked as unimplemented (KiIdleSchedule has a FIXME/TODO with ASSERT(FALSE)), and the project is self-described as alpha quality with known data corruption risks. The sheer scale (27K files) means some subsystems are more complete than others, and the codebase carries the accumulated debt of two decades of development with mixed coding styles across contributors.
Score Breakdown
Signal breakdown
Innovation
Craft
Traction
Scope
Evidence
Commits
1476
Contributors
100
Files
28360
Active weeks
52
Repository
Language
C
Stars
17290
Forks
2071
License
GPL-2.0