Red Bear OS — microkernel OS in Rust, based on Redox

Derivative of Redox OS (https://www.redox-os.org) adding: - AMD GPU driver (amdgpu) via LinuxKPI compat layer - ext4 filesystem support (ext4d scheme daemon) - ACPI fixes for AMD bare metal (x2APIC, DMAR, IVRS, MCFG) - Custom branding (hostname, os-release, boot identity) Build system is full upstream Redox with RBOS overlay in local/. Patches for kernel, base, and relibc are symlinked from local/patches/ and protected from make clean/distclean. Custom recipes live in local/recipes/ with symlinks into the recipes/ search path. Build: make all CONFIG_NAME=redbear-full Sync: ./local/scripts/sync-upstream.sh
2026-04-12 19:05:00 +01:00
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+# 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](03-WAYLAND-ON-REDOX.md)
+2. **KDE Plasma desktop** → see [05-KDE-PLASMA-ON-REDOX.md](05-KDE-PLASMA-ON-REDOX.md)
+3. **Linux driver compatibility layer** → see [04-LINUX-DRIVER-COMPAT.md](04-LINUX-DRIVER-COMPAT.md)
+
+## 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` | **Missing** | `relibc/src/header/signal/mod.rs` + `signal/types.rs` | Medium |
+| `timerfd_create/settime/gettime` | **Missing** | `relibc/src/header/sys_timerfd/` (NEW directory) | Medium |
+| `eventfd`/`eventfd_read`/`eventfd_write` | **Missing** | `relibc/src/header/sys_eventfd/` (NEW directory) | Low |
+| `F_DUPFD_CLOEXEC` | **Missing** | `relibc/src/header/fcntl/mod.rs` (add constant) | Low |
+| `MSG_CMSG_CLOEXEC` | **Missing** | `relibc/src/header/sys_socket/mod.rs` | Low |
+| `MSG_NOSIGNAL` | **Missing** | `relibc/src/header/sys_socket/mod.rs` | Low |
+| `open_memstream` | **Missing** | `relibc/src/header/stdio/src.rs` | Low |
+| 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 | — |
+
+**Proof of gap**: See `recipes/wip/wayland/libwayland/redox.patch` — all 7 missing APIs are stubbed there.
+
+### Layer 2: GPU / Display Infrastructure
+
+| Component | Status | Where to implement | Concrete doc |
+|-----------|--------|--------------------|-------------|
+| DRM/KMS scheme | **Missing** | New daemon: `redox-drm` crate | [04 §3](04-LINUX-DRIVER-COMPAT.md) |
+| GPU driver (Intel) | Experimental modeset only | `redox-drm/src/drivers/intel/` | [04 §3](04-LINUX-DRIVER-COMPAT.md) |
+| GEM buffers | **Missing** | `redox-drm/src/gem.rs` | [04 §3](04-LINUX-DRIVER-COMPAT.md) |
+| DMA-BUF sharing | **Missing** | `redox-drm/src/dmabuf.rs` | [04 §3](04-LINUX-DRIVER-COMPAT.md) |
+| Mesa hardware backend | **Missing** | Mesa winsys for Redox DRM | [03 §3.4](03-WAYLAND-ON-REDOX.md) |
+| GPU OpenGL | Software only | Blocked on GPU driver | [04](04-LINUX-DRIVER-COMPAT.md) |
+
+### Layer 3: Input Stack
+
+| Component | Status | Where to implement | Concrete doc |
+|-----------|--------|--------------------|-------------|
+| evdev daemon | **Missing** | New: `recipes/core/evdevd/` | [03 §2](03-WAYLAND-ON-REDOX.md) |
+| udev shim | **Missing** | New: `recipes/wip/wayland/udev-shim/` | [03 §2](03-WAYLAND-ON-REDOX.md) |
+| libinput | **Missing** | `recipes/wip/wayland/libinput/` (NEW) | [03 §2](03-WAYLAND-ON-REDOX.md) |
+| XKB layouts | **Done** | `xkeyboard-config` ported | — |
+| seatd | Recipe exists, untested | `recipes/wip/wayland/seatd/` | — |
+
+### Layer 4: Wayland Protocol
+
+| Component | Status | Recipe | Blocker |
+|-----------|--------|--------|---------|
+| libwayland | Patched, broken timers | `recipes/wip/wayland/libwayland/` | Layer 1 POSIX gaps |
+| 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 | Not ported | [05 Phase KDE-A](05-KDE-PLASMA-ON-REDOX.md) |
+| KDE Frameworks | Not ported | [05 Phase KDE-B](05-KDE-PLASMA-ON-REDOX.md) |
+| KWin | Not ported | [05 Phase KDE-C](05-KDE-PLASMA-ON-REDOX.md) |
+| Plasma Shell | Not ported | [05 Phase KDE-C](05-KDE-PLASMA-ON-REDOX.md) |
+| D-Bus | **Ported** | `config/x11.toml` has it working |
+
+### Layer 6: Linux Driver Compatibility
+
+| Component | Status | Concrete doc |
+|-----------|--------|-------------|
+| `redox-driver-sys` crate | Not started | [04 §3](04-LINUX-DRIVER-COMPAT.md) |
+| `linux-kpi` C headers | Not started | [04 §3](04-LINUX-DRIVER-COMPAT.md) |
+| i915 C driver port | Not started | [04 §4](04-LINUX-DRIVER-COMPAT.md) |
+| amdgpu C driver port | Not started | [04 §5](04-LINUX-DRIVER-COMPAT.md) |
+
+---
+
+## Concrete Roadmap with Milestones
+
+### Milestone M1: "libwayland works natively" (2-4 weeks)
+- Implement 7 POSIX APIs in relibc (see Layer 1 table)
+- Remove `redox.patch` from libwayland recipe
+- **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)