Phase 11: KDE Plasma 6 Default Desktop Integration

Version: v0.24.0 | Date: March 2026 | Status: COMPLETE

Overview

Phase 11 makes KDE Plasma 6 the default desktop session for VeridianOS. Building on the porting infrastructure (Phase 9) and limitation remediation (Phase 10), this phase adds session configuration, lifecycle management, and automatic fallback so that the startgui command launches KDE Plasma by default while gracefully recovering if KDE fails to start.

Key Deliverables

  • Session configuration: /etc/veridian/session.conf parser that reads the configured session type (plasma, builtin, or custom) at startup
  • KDE session manager: Full lifecycle management including desktop initialization, framebuffer console handoff, user process launch via load_user_program and run_user_process, page table cleanup, zombie process reaping, and framebuffer console restore on session exit
  • Default session switching: startgui now launches KDE Plasma 6 by default; startgui builtin forces the built-in desktop environment
  • Startup failure detection: TSC-based timing detects early KDE crashes and automatically falls back to the built-in desktop environment
  • Init script integration: --from-kernel flag in veridian-kde-init.sh distinguishes boot-time launch from manual invocation
  • KdePlasma session type: New variant added to the display manager's session enumeration

Technical Highlights

  • The session config reader parses simple key=value files without heap allocation, using fixed-size buffers suitable for early boot before the allocator is fully initialized
  • Startup failure detection measures elapsed TSC ticks between process launch and exit; if the KDE session terminates within the threshold, the system assumes a crash and reverts to the built-in compositor
  • Page table cleanup on session exit prevents address space leaks when switching between desktop sessions

New Files

  • kernel/src/desktop/session_config.rs -- Session configuration parser
  • kernel/src/desktop/kde_session.rs -- KDE session lifecycle manager
  • userland/config/default-session.conf -- Default session configuration

Files and Statistics

  • Sprints: 4 (11.0 through 11.3)
  • Files added: 3
  • Files modified: 14
  • Lines of code: +496
  • Tests added: 12 (9 session config parsing, 3 KDE session validation)