RedBear-OS/docs/02-GAP-ANALYSIS.md

02 — Gap Analysis & Roadmap

Overview

This document maps the distance between current Redox OS 0.9.0 and three goals:

1. Wayland compositor support → see 03-WAYLAND-ON-REDOX.md
2. KDE Plasma desktop → see 05-KDE-PLASMA-ON-REDOX.md
3. Linux driver compatibility layer → see 04-LINUX-DRIVER-COMPAT.md

Status Correction (2026-04-14)

Most of this document is a historical roadmap and no longer reflects the repository's current state. Use the matrix below as the authoritative phase summary before reading the older milestone text.

Layer / Phase	Current repo state	Evidence
P0 ACPI / bare-metal boot	Complete in-tree	local/docs/ACPI-FIXES.md, local/patches/kernel/redox.patch, local/patches/base/redox.patch
P1 driver infrastructure	Complete in-tree, compile-oriented	local/recipes/drivers/redox-driver-sys/, local/recipes/drivers/linux-kpi/, local/recipes/system/firmware-loader/
P2 DRM / AMD+Intel display	Complete in-tree, hardware validation pending	local/docs/P2-AMD-GPU-DISPLAY.md, local/recipes/gpu/redox-drm/, local/recipes/gpu/amdgpu/
P3 POSIX + input	Implemented in-tree; consumer-visible signalfd/timerfd/eventfd/open_memstream header-export path fixed in this repo pass; runtime validation still pending	recipes/core/relibc/source/src/header/, recipes/core/relibc/source/include/sys/signalfd.h, local/patches/relibc/, local/recipes/system/evdevd/, local/recipes/system/udev-shim/
P4 Wayland stack	Partially complete	recipes/wip/wayland/, recipes/wip/libs/other/libinput/, recipes/wip/services/seatd/
P5 AMD acceleration / IOMMU	Partial, but no longer blocked on basic QEMU first-use proof	local/recipes/gpu/amdgpu/, local/recipes/system/iommu/
P6 KDE Plasma	In progress with mixed real builds and stubs/shims	config/redbear-kde.toml, local/recipes/kde/, local/docs/QT6-PORT-STATUS.md

Ordered Remaining Gaps

1. Validate the completed P3→P4 bridge in practice: libwayland now rebuilds with signalfd, timerfd, eventfd, open_memstream, MSG_CMSG_CLOEXEC, and MSG_NOSIGNAL restored, but compositor/runtime validation is still outstanding.
2. Complete P4 runtime path: libinput/seatd/GBM/Wayland compositor integration is still incomplete even though the base libraries now build, seatd now builds for Redox, and the KDE runtime config now starts a seatd service.
3. Separate KDE real builds from scaffolding: parts of the KDE stack are genuine builds, while others are shimmed or stubbed only to satisfy dependency resolution.
4. Hardware validation remains open for AMD/Intel DRM and the IOMMU path, even though the IOMMU daemon now builds and its guest-driven QEMU first-use proof passes.

P7 Note

The repository's tracked phase model currently stops at P6. What a user might call "P7" only appears here as later milestone-style work (for example M7/M8 below), not as a first-class implemented phase with its own config/recipe/doc boundary.

Dependency Chain: Hardware → KDE Desktop

┌─────────────────────────────────────────────────────────┐
│                    KDE Plasma Desktop                     │
│  (KWin compositor, Plasma Shell, Qt, KDE Frameworks)    │
├─────────────────────────────────────────────────────────┤
│                    Wayland Protocol                       │
│  (libwayland, wayland-protocols, compositor)             │
├─────────────────────────────────────────────────────────┤
│                    Graphics Stack                         │
│  (Mesa3D OpenGL/Vulkan, GBM, libdrm, GPU driver)        │
├─────────────────────────────────────────────────────────┤
│                    Kernel Interfaces                      │
│  (DRM/KMS, GEM/TTM, DMA-BUF, evdev, udev)              │
├─────────────────────────────────────────────────────────┤
│                    Hardware                               │
│  (GPU: AMD/Intel/NVIDIA, Input: keyboard/mouse/touch)   │
└─────────────────────────────────────────────────────────┘

Gap Matrix with Concrete File References

Layer 1: POSIX Interfaces (relibc)

API	Status	Where to implement	Effort
signalfd/signalfd4	Implemented in-tree	relibc/src/header/signal/mod.rs + signal/signalfd.rs	Runtime validation still needed
timerfd_create/settime/gettime	Implemented in-tree	relibc/src/header/sys_timerfd/	Runtime validation still needed
eventfd/eventfd_read/eventfd_write	Implemented in-tree	relibc/src/header/sys_eventfd/	Runtime validation still needed
F_DUPFD_CLOEXEC	Implemented in-tree	relibc/src/header/fcntl/mod.rs	Verify against downstream consumers
MSG_CMSG_CLOEXEC	Implemented in-tree	relibc/src/header/sys_socket/mod.rs	Verify against downstream consumers
MSG_NOSIGNAL	Implemented in-tree	relibc/src/header/sys_socket/mod.rs	Verify against downstream consumers
open_memstream	Implemented in-tree	relibc/src/header/stdio/open_memstream.rs	Verify against downstream consumers
UDS + FD passing	Done	Already implemented	—
epoll (event scheme)	Done	Redox scheme:event	—
mmap/mprotect	Done	Kernel syscalls	—
fork/exec	Done	Userspace via thisproc: scheme	—

Current blocker: The build-side relibc/libwayland bridge is now in place, but downstream Wayland still needs runtime validation and the wider compositor stack (evdevd/seatd/DRM/GBM) is still incomplete.

Layer 2: GPU / Display Infrastructure

Component	Status	Where to implement	Concrete doc
DRM/KMS scheme	Present in-tree	local/recipes/gpu/redox-drm/	04 §3
GPU driver (Intel)	Experimental modeset only	redox-drm/src/drivers/intel/	04 §3
GEM buffers	Present in-tree	local/recipes/gpu/redox-drm/source/src/gem.rs	04 §3
DMA-BUF sharing	Present in-tree	local/recipes/gpu/redox-drm/source/src/dmabuf.rs	04 §3
Mesa hardware backend	Missing	Mesa winsys for Redox DRM	03 §3.4
GPU OpenGL	Software only	Blocked on GPU driver	04

Layer 3: Input Stack

Interpretation note: paths under recipes/wip/ in the matrix below should be read as upstream WIP inputs or historical references, not automatically as the current Red Bear shipping source of truth. Under the Red Bear WIP policy, upstream WIP may still be mirrored, fixed, and shipped from the local overlay instead.

Component	Status	Where to implement	Concrete doc
evdev daemon	Present in-tree	local/recipes/system/evdevd/	03 §2
udev shim	Present in-tree	local/recipes/system/udev-shim/	03 §2
libinput	Present as WIP port	recipes/wip/libs/other/libinput/	03 §2
XKB layouts	Done	xkeyboard-config ported	—
seatd	Builds and is wired into KDE config, runtime unvalidated	recipes/wip/services/seatd/, config/redbear-kde.toml	—

Layer 4: Wayland Protocol

Interpretation note: the recipes/wip/wayland/* paths below are still useful references for upstream status, but Red Bear should not treat them as automatically preferred shipping sources while they remain upstream WIP.

Component	Status	Recipe	Blocker
libwayland	Patched, downstream compatibility workarounds remain	recipes/wip/wayland/libwayland/	Reduce/remove redox.patch and verify runtime behavior
cosmic-comp	No keyboard input	recipes/wip/wayland/cosmic-comp/	Layer 3 libinput
smallvil (Smithay)	Basic, slow	recipes/wip/wayland/smallvil/	Layer 2+3 for DRM+input
wlroots/sway/hyprland	Not tested	recipes/wip/wayland/wlroots/	Layer 2+3

Layer 5: KDE Plasma

Component	Status	Concrete doc
Qt 6	Ported in-tree	05 Phase KDE-A
KDE Frameworks	Partially ported in-tree	05 Phase KDE-B
KWin	Recipe exists, still incomplete	05 Phase KDE-C
Plasma Shell	Recipe exists, still incomplete	05 Phase KDE-C
D-Bus	Ported	config/x11.toml has it working

Layer 6: Linux Driver Compatibility

Component	Status	Concrete doc
redox-driver-sys crate	Present in-tree	04 §3
linux-kpi C headers	Present in-tree	04 §3
i915 C driver port	Not started as Linux C port	04 §4
amdgpu C driver port	Present in-tree, hardware validation pending	04 §5

---

Concrete Roadmap with Milestones

Milestone M1: "libwayland works natively" (2-4 weeks)

• Build-side part now substantially complete: relibc exports the needed consumer-visible POSIX headers/symbols and libwayland rebuilds with only residual Redox-specific build tweaks
• Remaining work: runtime validation (wayland-rs_simple_window, compositor bring-up)
• Test: wayland-rs_simple_window runs without crashes
• Delivers: libwayland, wayland-protocols, libdrm all build natively

Milestone M2: "Input works via libinput" (4-6 weeks after M1)

• Build evdevd daemon (reads Redox input schemes, exposes /dev/input/eventX)
• Build udev-shim for hotplug
• Port libinput with evdev backend
• Test: libinput list-devices shows keyboard and mouse
• Delivers: Full input stack for any Wayland compositor

Milestone M3: "Display output via DRM" (8-12 weeks, parallel with M2)

• Build redox-driver-sys crate
• Build redox-drm daemon with Intel native driver
• Register scheme:drm/card0
• Test: modetest -M intel shows display modes
• Delivers: KMS modesetting, hardware display control

Milestone M4: "Wayland compositor with input + display" (2-4 weeks after M2+M3)

• Add Redox backends to Smithay (input + DRM + EGL)
• Build smallvil with Redox backends
• Test: Compositor takes over display, keyboard/mouse work
• Delivers: First fully functional Wayland compositor on Redox

Milestone M5: "Qt application runs" (6-8 weeks after M4)

• Port qtbase with Wayland QPA
• Port qtwayland, qtdeclarative
• Test: Qt widget app shows window on compositor
• Delivers: Qt development on Redox

Milestone M6: "KDE app runs" (6-8 weeks after M5)

• Port KDE Frameworks (25 frameworks)
• Port one KDE app (e.g., Kate)
• Test: Kate editor opens and edits a file
• Delivers: KDE application ecosystem begins

Milestone M7: "KDE Plasma desktop" (4-6 weeks after M6)

• Port KWin (DRM/Wayland backend)
• Port Plasma Shell
• Create config/kde.toml
• Test: Full Plasma session boots
• Delivers: KDE Plasma as a usable desktop

Milestone M8: "Linux GPU drivers" (8-12 weeks, parallel track from M3)

• Build linux-kpi C headers
• Port i915 as proof of concept
• Port amdgpu for AMD support
• Test: amdgpu drives AMD GPU on Redox
• Delivers: Broad GPU hardware support via Linux driver ports

---

Parallel Execution Plan

Week 1-4:     M1 (relibc POSIX gaps)
Week 3-12:    M2 (evdev input) ──── parallel ──── M3 (DRM/KMS)
Week 13-16:   M4 (Wayland compositor = M2 + M3 + M1)
Week 13-24:   M8 (Linux driver compat, parallel with M4-M6)
Week 17-24:   M5 (Qt Foundation)
Week 25-32:   M6 (KDE Frameworks)
Week 33-38:   M7 (Plasma Desktop)

Total to KDE Plasma: ~38 weeks (~9 months) with 2 developers. Total to Linux driver compat: ~24 weeks (~6 months) in parallel.

Critical Path

M1 (POSIX) ──────────────────────────────────────┐
                                                   │
M3 (DRM/KMS) ─────────── M4 (Compositor) ── M5 (Qt) ── M6 (KDE) ── M7 (Plasma)
       │                  ↑                      │
M2 (Input) ──────────────┘                       M8 (Linux drivers, parallel)

Shortest path to a desktop: M1 → M2 → M3 (parallel) → M4 → M5 → M6 → M7 Shortest path to GPU drivers: M3 → M8 (can start as soon as redox-driver-sys exists)