RedBear-OS/local/docs/DBUS-INTEGRATION-PLAN.md

Red Bear OS D-Bus Integration Plan

Implementation status (2026-04-29): All DBUS plan code artifacts are build-verified. Remaining items are runtime validation gates requiring QEMU.

Version: 3.0 — 2026-04-29 Status: Active plan aligned with the desktop path v4.0 Scope: Full D-Bus infrastructure for KDE Plasma 6 on Wayland, tightly integrated with Redox scheme IPC Parent plan: local/docs/CONSOLE-TO-KDE-DESKTOP-PLAN.md (v4.0)

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1. Executive Summary

D-Bus is mandatory infrastructure for KDE Plasma 6 — not optional, not deferrable. KDE services, KWin, plasmashell, and virtually every KF6 framework communicate over D-Bus at runtime.

Red Bear OS already has D-Bus 1.16.2 building with a 24-line redox.patch, the system bus wired in redbear-full profile (historical redbear-kde name retired), and QtDBus enabled in qtbase. This is a solid foundation, but it is only the transport layer. What's missing is the service layer — the D-Bus services that KDE actually expects to talk to.

This plan defines a Redox-native D-Bus service architecture built on three decisions:

1. Use dbus-daemon (reference implementation), not dbus-broker. It works without systemd, supports traditional .service file activation, and is battle-tested on non-systemd OSes (Alpine, Void, Gentoo/OpenRC).

2. Build redbear-sessiond — a small Rust daemon (using zbus) that exposes the bounded org.freedesktop.login1 surface KWin already expects, plus a few higher-level manager helpers (GetUser, ActivateSessionOnSeat, lock/unlock/terminate helpers) that broader KDE session plumbing can call without forcing Red Bear into an elogind-sized reimplementation. Not elogind (too Linux-shaped), not ConsoleKit2 (legacy), but a targeted login1-compatible service backed by Redox's native seat/device model.

3. Keep schemes and D-Bus separate. Schemes are the native resource plane. D-Bus is the desktop compatibility plane. Only add D-Bus facades when there is a real published freedesktop contract worth matching (login1, later NetworkManager, UPower, UDisks2).

Minimum viable D-Bus stack for KWin: system bus + session bus + redbear-sessiond with login1 subset. No polkit, no UPower, no udisks2, no NetworkManager required for first KWin compositor bring-up.

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2. Architecture Principles

2.1 Schemes = Native Resource Plane, D-Bus = Desktop Compatibility Plane

┌─────────────────────────────────────────────────────────────────────┐
│  KDE Plasma / KWin / KF6                                           │
│  (speaks D-Bus, expects freedesktop contracts)                     │
├─────────────────────────────────────────────────────────────────────┤
│  D-Bus Compatibility Services                                      │
│  redbear-sessiond (login1)   redbear-notifications   redbear-polkit│
│  (zbus-based Rust daemons, translating D-Bus ↔ scheme calls)      │
├─────────────────────────────────────────────────────────────────────┤
│  dbus-daemon (system bus + session bus)                            │
│  Classic .service activation, XML policies                         │
├─────────────────────────────────────────────────────────────────────┤
│  Redox Schemes (native IPC)                                        │
│  scheme:pci  scheme:input  scheme:drm  scheme:net  scheme:acpi    │
│  evdevd       udev-shim     redox-drm   netd        acpid         │
└─────────────────────────────────────────────────────────────────────┘

D-Bus services wrap scheme resources into freedesktop-compatible contracts. They do not replace or mirror schemes. Each D-Bus service holds only the scheme handles it needs, and clients never get raw scheme access through D-Bus.

2.2 Use Existing Contracts, Don't Invent New Ones

Namespace	Use For
org.freedesktop.login1	Session/seat/device tracking — KWin expects this
org.freedesktop.Notifications	Desktop notifications — kf6-knotifications expects this
org.freedesktop.NetworkManager	Deferred — not in current Red Bear OS scope
org.freedesktop.UPower	Power management — PowerDevil expects this
org.freedesktop.UDisks2	Storage management — Solid/udisks backend expects this
org.freedesktop.PolicyKit1	Privileged actions — KAuth expects this
org.kde.*	KDE-specific services — KWin, plasmashell, kglobalaccel, kded6
org.redbear.*	Red Bear-specific services that don't match any freedesktop contract

2.3 No Generic Scheme→D-Bus Bridge

Do NOT build a universal translator that mirrors every scheme as a D-Bus object. Each D-Bus compatibility service is hand-written for a specific freedesktop contract, backed by the specific schemes it needs. This keeps the architecture honest and avoids a leaky abstraction.

2.4 Rust-Native for New Services, C for Existing Daemons

Component	Implementation	Why
dbus-daemon	C (freedesktop upstream)	Battle-tested, minimal redox.patch, no reason to rewrite
libdbus-1	C (part of dbus package)	Required by QtDBus, kf6-kdbusaddons
redbear-sessiond	Rust + zbus	New code, Rust-native OS, async, strong typing
Future compat daemons	Rust + zbus	Same reasons as redbear-sessiond
KDE apps (KWin, plasmashell)	C++ via QtDBus	Upstream KDE code, not our concern

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3. Current State Assessment

3.1 What Exists and Works

Component	Location	Status	Detail
D-Bus 1.16.2 daemon	recipes/wip/services/dbus/	✅ Builds, bounded runtime	24-line redox.patch (epoll guard + socketpair fix), meson build with systemd disabled
libdbus-1	Part of dbus package	✅ Builds	libdbus-1.so.3.38.3 staged, pkgconfig and cmake files present
QtDBus	recipes/wip/qt/qtbase/	✅ Enabled	FEATURE_dbus=ON for target build, Qt6DBus module present
kf6-kdbusaddons	local/recipes/kde/kf6-kdbusaddons/	✅ Builds	KF6 D-Bus convenience wrappers, provides qdbus tool integration
D-Bus system bus	config/redbear-full.toml	✅ Wired	12_dbus.service launches dbus-daemon --system, messagebus user (uid=100), /var/lib/dbus + /run/dbus directories
D-Bus session bus	local/recipes/system/redbear-greeter/source/redbear-kde-session	✅ Scripted	redbear-kde-session launches dbus-launch --sh-syntax before KWin
seatd	config/redbear-full.toml	✅ Wired	13_seatd.service, LIBSEAT_BACKEND=seatd, SEATD_SOCK=/run/seatd.sock
kf6-kservice	local/recipes/kde/kf6-kservice/	✅ Builds	Depends on kf6-kdbusaddons
kf6-kglobalaccel	local/recipes/kde/kf6-kglobalaccel/	✅ Builds	Depends on kf6-kdbusaddons
Session activation scaffolds	local/recipes/system/redbear-dbus-services/	✅ Staged	Session .service files now cover kded6, kglobalaccel, ActivityManager, JobViewServer, ksmserver, notifications, and StatusNotifierWatcher
KWin (D-Bus)	local/recipes/kde/kwin/	✅ USE_DBUS=ON	Registers org.kde.KWin on session bus

3.2 What Exists But Is Incomplete

Component	Location	Status	Gap
elogind	recipes/wip/services/elogind/	⚠️ Recipe only	"not compiled or tested" — needs libeudev + libcap, too Linux-shaped for Redox
kf6-knotifications	local/recipes/kde/kf6-knotifications/	⚠️ D-Bus ON (scaffold-backed)	Built with -DUSE_DBUS=ON, but current notification daemon is still a minimal scaffold
kf6-kio	local/recipes/kde/kf6-kio/	⚠️ D-Bus OFF	Built with -DUSE_DBUS=OFF — D-Bus IPC disabled, has systemd1 XML interfaces in source
kf6-solid	local/recipes/kde/kf6-solid/	⚠️ D-Bus OFF	Built with -DUSE_DBUS=OFF — UDev/UPower/udisks2 backends all disabled
kf6-kwallet	local/recipes/kde/kf6-kwallet/	⚠️ Not in enabled subset	Real API-only cmake build (no daemon); exists in-tree, not part of current redbear-full
plasma-workspace	local/recipes/kde/plasma-workspace/	⚠️ Partial	Explicit dbus dep; sub-services activation files staged; runtime proof requires QEMU

3.3 What Ships Today (Scaffolds and Deferred Items)

Component	Namespace	Purpose	KDE Consumer
Session tracker	org.freedesktop.login1	Session/seat/device brokering scaffold	KWin (hard requirement for DRM/libinput)
Notification daemon	org.freedesktop.Notifications	Notification service scaffold	kf6-knotifications
Polkit	org.freedesktop.PolicyKit1	Authorization scaffold (always-permit)	KAuth
UPower	org.freedesktop.UPower	Provisional ACPI-backed power service; current backing power surface is provisionally bounded; broader ACPI validation requires QEMU/hardware	kf6-solid, PowerDevil
UDisks2	org.freedesktop.UDisks2	Bounded real disk.* / partition enumeration	kf6-solid
D-Bus service files	/usr/share/dbus-1/	Activation is staged and shipped for the current scaffold services plus bounded KDE session daemons (kded6, kglobalaccel, ActivityManager, JobViewServer, ksmserver)	All D-Bus services
D-Bus policy files	/etc/dbus-1/	Policy is staged and shipped for the current scaffold services	All D-Bus services
zbus crate marker	local/recipes/libs/zbus/	Build-ordering marker; actual zbus crate is fetched by downstream Cargo builds	Future Rust D-Bus services

Deferred and not shipped in the current implementation cycle:

• org.freedesktop.NetworkManager / redbear-nm — Red Bear OS uses redbear-netctl for now

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4. Gap Analysis

4.1 Critical Path Gaps (blocks KWin compositor)

KWin needs:
  dbus-daemon --system          ✅ exists, wired
  dbus-daemon --session         ✅ exists, wired in redbear-kde-session
  org.freedesktop.login1        ✅ scaffold exists — session/device brokering implemented minimally
  org.kde.KWin (self-register)  ✅ KWin does this itself (dbusinterface.cpp)

The single critical runtime-risk area is org.freedesktop.login1. KWin's session_logind.cpp calls TakeDevice(), ReleaseDevice(), TakeControl(), and listens for PauseDevice/ResumeDevice signals. Without this, KWin cannot take ownership of DRM/input devices through the freedesktop session protocol.

KWin's session selection chain is: logind → ConsoleKit → Noop. The Noop backend returns -1 from openRestricted() — meaning it can start but cannot manage real devices.

4.2 Desktop Session Gaps (blocks plasma-workspace)

plasma-workspace needs:
  org.kde.KWin                    ✅ KWin provides
  org.kde.kglobalaccel            ❌ activation file removed (honest absence) — daemon binary not yet built/runtime-validated
  org.kde.kded6                   ❌ activation file removed (honest absence) — daemon binary not yet built/runtime-validated
  org.kde.plasmashell             ✅ plasmashell provides (self-register)
  org.kde.osdService              ✅ plasmashell provides
  org.freedesktop.Notifications   ✅ scaffold exists — current daemon logs to stderr only

4.3 Full Desktop Gaps (blocks complete KDE Plasma)

Complete Plasma needs (after re-enabling disabled components):
  org.freedesktop.UPower          ⚠️ service exists, but ACPI-backed power reporting is still provisional and needs Wave 3 closure in the ACPI plan before kf6-solid can rely on it
  org.freedesktop.UDisks2         ✅ bounded real enumeration exists — build-verified; supplementary QEMU runtime validation for kf6-solid
  org.freedesktop.NetworkManager  ⏸️ DEFERRED — Red Bear OS uses redbear-netctl for now
  org.freedesktop.PolicyKit1      ⚠️ scaffold exists — KAuth still blocked on missing PolkitQt6-1 packaging
  org.freedesktop.StatusNotifierWatcher  ✅ activation file staged — runtime watcher build-verified; supplementary QEMU broader desktop proof
  org.kde.JobViewServer           ❌ activation file removed (honest absence) — kuiserver binary not yet built
  org.kde.ksmserver               ❌ activation file removed (honest absence) — session manager binary not yet built
  org.kde.ActivityManager         ❌ activation file removed (honest absence) — activity manager binary not yet built
  org.freedesktop.ScreenSaver: deferred (not on critical path) — screen locking

4.4 Build System Gaps

Gap	Detail
zbus recipe is only a marker	Build-ordering marker exists; actual Rust crate comes from downstream Cargo resolution
D-Bus service activation is scaffolded	/usr/share/dbus-1/system-services/ and session-services/ are staged for current services
D-Bus policy configuration is scaffolded	/etc/dbus-1/system.d/ XML policy files are staged for current services
Activation coverage: system services + KDE session daemons staged (.service files present); screen-lock deferred (non-critical)
kf6-knotifications now D-Bus enabled	Enabled against a minimal notification daemon scaffold
kf6-solid D-Bus disabled	Must re-enable after UPower/udisks2 backends exist
kf6-kio D-Bus disabled	Must re-enable for full KIO functionality

---

5. Architecture Design

5.1 Overall Stack

┌──────────────────────────────────────────────────────────────────────────┐
│                     KDE Plasma 6 Desktop Session                        │
│   plasmashell, kwin_wayland, kded6, kglobalaccel, plasma applets        │
├──────────────────────────────────────────────────────────────────────────┤
│                     Session Bus (per-user)                               │
│   Started by: redbear-kde-session via dbus-launch or dbus-run-session   │
│   Policy: /etc/dbus-1/session.conf                                      │
│   Services: /usr/share/dbus-1/session-services/                         │
│   ┌──────────────────────────────────────────────────────────────────┐  │
│   │  org.kde.KWin           (KWin self-registers)                   │  │
│   │  org.kde.plasmashell    (plasmashell self-registers)            │  │
│   │  org.kde.kglobalaccel   (daemon NOT built — activation removed)   │  │
│   │  org.kde.kded6          (daemon NOT built — activation removed)   │  │
│   │  org.kde.ActivityManager (daemon NOT built — activation removed)  │  │
│   │  org.kde.JobViewServer  (daemon NOT built — activation removed)   │  │
│   │  org.kde.ksmserver      (daemon NOT built — activation removed)   │  │
│   │  org.freedesktop.Notifications  (redbear-notifications)         │  │
│   │  org.freedesktop.StatusNotifierWatcher  (redbear-statusnotifier)│  │
│   └──────────────────────────────────────────────────────────────────┘  │
├──────────────────────────────────────────────────────────────────────────┤
│                     System Bus (machine-global)                          │
│   Started by: Redox init (12_dbus.service)                              │
│   Policy: /etc/dbus-1/system.conf + system.d/*.conf                     │
│   Services: /usr/share/dbus-1/system-services/                          │
│   ┌──────────────────────────────────────────────────────────────────┐  │
│   │  org.freedesktop.login1   (redbear-sessiond)                    │  │
│   │  org.freedesktop.DBus     (dbus-daemon itself)                  │  │
│   │  [Phase 4+] org.freedesktop.UPower       (redbear-upower)       │  │
│   │  [Phase 4+] org.freedesktop.UDisks2      (redbear-udisks)       │  │
│   │  [deferred] org.freedesktop.NetworkManager  (not in scope)      │  │
│   │  [Phase 4+] org.freedesktop.PolicyKit1   (redbear-polkit)       │  │
│   └──────────────────────────────────────────────────────────────────┘  │
├──────────────────────────────────────────────────────────────────────────┤
│                     dbus-daemon 1.16.2                                   │
│   C reference implementation, redox.patch for epoll + socketpair         │
│   systemd disabled, legacy GUI autolaunch disabled                       │
│   Classic .service file activation                                       │
├──────────────────────────────────────────────────────────────────────────┤
│                     Redox Schemes (native IPC)                           │
│   scheme:input → evdevd → /dev/input/eventX                             │
│   scheme:drm → redox-drm → DRM/KMS                                      │
│   scheme:pci → pcid-spawner → PCI device access                         │
│   scheme:net → netd → network interfaces                                │
│   scheme:firmware → firmware-loader → GPU blobs                         │
│   scheme:acpi → acpid → ACPI/DMI data                                   │
│   scheme:seat → seatd → seat management (libseat API)                   │
└──────────────────────────────────────────────────────────────────────────┘

5.2 D-Bus Service Lifecycle

Boot:
  1. Redox init starts 12_dbus.service → dbus-daemon --system
  2. Redox init starts 13_redbear-sessiond.service → redbear-sessiond
     (registers org.freedesktop.login1 on system bus)
  3. Redox init starts 13_seatd.service → seatd

Session launch (redbear-kde-session):
  4. dbus-daemon --system already running
  5. eval $(dbus-launch --sh-syntax)  →  session bus started
  6. export DBUS_SESSION_BUS_ADDRESS, XDG_SESSION_ID, XDG_SEAT, XDG_RUNTIME_DIR
  7. redbear-compositor --drm  →  launches KWin on the session bus and owns the Wayland socket lifecycle for the current Red Bear session path
  8. [later] plasmashell  →  registers org.kde.plasmashell on session bus

5.3 Service Activation Strategy

Service Type	Activation Method	Why
System bus core (login1)	Redox init	Must be running before any desktop session
System bus compat (UPower, NM)	Redox init or D-Bus activation	Can be started lazily, but init is simpler
Session bus KDE services (kglobalaccel, kded6)	D-Bus activation (classic .service files)	KDE expects this, standard pattern
Session bus KDE shell (KWin, plasmashell)	Explicit launch in redbear-kde-session	Must start in specific order with env vars
Session bus compat (notifications, tray)	D-Bus activation	Standard freedesktop pattern

---

6. Component Specifications

6.1 redbear-sessiond — Session/Seat/Device Broker

Purpose: Provides the org.freedesktop.login1 D-Bus interface that KWin requires for device access control, session management, and power signaling.

Implementation: Rust binary, uses zbus for D-Bus, backed by Redox scheme IPC.

Bus: System bus Bus name: org.freedesktop.login1

D-Bus Interfaces

/org/freedesktop/login1 — Manager

Interface	Method/Signal	Signature	Description
org.freedesktop.login1.Manager	GetSession	s → o	Returns session object path by ID
	GetUser	u → o	Returns the current user object path for the bounded active session owner
	GetUserByPID	u → o	Returns the current user object path for the bounded active session surface
	ListSessions	→ a(susso)	Lists all active sessions
	GetSeat	s → o	Returns seat object path
	ActivateSessionOnSeat	ss →	Marks the bounded session active on the requested seat
	LockSessions / UnlockSessions	→	Updates the bounded session lock hint for KDE session plumbing
	TerminateUser	u →	Marks the bounded active user session closing
	signal PrepareForSleep	b	Emitted before/after sleep (false=resume, true=suspend)
	signal PrepareForShutdown	b	Emitted before/after shutdown
org.freedesktop.DBus.Properties	Get	ss → v	Property access
	GetAll	s → a{sv}	All properties

/org/freedesktop/login1/session/c1 — Session

Interface	Method/Signal	Signature	Description
org.freedesktop.login1.Session	Activate	→	Activate this session
	TakeControl	b →	Take exclusive control of session devices
	ReleaseControl	→	Release device control
	TakeDevice	uu → h	Take device by major/minor (returns fd)
	ReleaseDevice	uu →	Release device by major/minor
	PauseDeviceComplete	uu →	Acknowledge device pause
	property Active	b	Is this session active
	property Seat	(so)	Seat this session belongs to
	property User	(uo)	User info
	property Type	s	Session type (e.g. "wayland")
	signal PauseDevice	uus	Device paused (major, minor, type)
	signal ResumeDevice	uuh	Device resumed (major, minor, fd)

/org/freedesktop/login1/seat/seat0 — Seat

Interface	Method/Signal	Signature	Description
org.freedesktop.login1.Seat	SwitchTo	u →	Switch to VT number
	property ActiveSession	(so)	Currently active session
	property Sessions	a(so)	All sessions on this seat

Scheme Backing

redbear-sessiond translates login1 D-Bus calls into Redox scheme operations:

login1 Method	Redox Backend
TakeDevice(major, minor)	Opens the corresponding scheme path (e.g., /scheme/drm/card0 for DRM, /dev/input/eventX for input) using udev-shim's device enumeration to resolve major/minor → scheme path
ReleaseDevice(major, minor)	Closes the scheme file descriptor
TakeControl(force)	Records compositor ownership; no kernel-level operation needed (seatd already provides seat arbitration)
Activate()	Sets session as active; signals to compositor via D-Bus
SwitchTo(vt)	Delegates to inputd -A <vt> (existing Redox VT switching)
PrepareForSleep	Future/conditional: only available once ACPI sleep eventing exists; currently a known gap in the ACPI stack
PrepareForShutdown	Generated from the current ACPI-backed shutdown signal path via scheme:acpi / kstop

Device Number Mapping

KWin identifies devices by Linux major/minor numbers. Red Bear OS must maintain a stable mapping from (major, minor) → scheme path:

Device Class	Major	Minor Source	Scheme Path
DRM/GPU	226 (Linux DRM major)	card index (0, 1...)	/scheme/drm/card0
Input (evdev)	13 (Linux input major)	event index (64+)	/dev/input/eventX (via evdevd)
Framebuffer	29 (Linux fb major)	fb index (0, 1...)	/dev/fbX

The udev-shim daemon already maintains a device database that maps scheme paths to traditional /dev/ paths with major/minor numbers. redbear-sessiond should query this database rather than maintaining its own mapping.

Configuration

local/recipes/system/redbear-sessiond/
├── recipe.toml              # cargo template, depends on dbus (for libdbus headers)
├── source/
│   ├── Cargo.toml           # zbus + libredox + redox-syscall deps
│   └── src/
│       ├── main.rs          # Daemon entry: fork, signal handling, D-Bus registration
│       ├── manager.rs       # org.freedesktop.login1.Manager interface
│       ├── session.rs       # org.freedesktop.login1.Session interface
│       ├── seat.rs          # org.freedesktop.login1.Seat interface
│       ├── device_map.rs    # major/minor → scheme path resolution (via udev-shim)
│       └── acpi_watcher.rs  # current kstop-backed shutdown watcher; sleep signaling remains future-only until ACPI sleep eventing exists

6.2 D-Bus Service Activation Files

System Bus Service Files

Location: /usr/share/dbus-1/system-services/

org.freedesktop.login1.service:
  [D-BUS Service]
  Name=org.freedesktop.login1
  Exec=/usr/bin/redbear-sessiond
  User=root
  SystemdService=  # intentionally empty — no systemd

Session Bus Service Files

Location: /usr/share/dbus-1/session-services/

REMOVED (honest absence — daemons not built, Exec pointed to non-existent
binaries; will be re-added when the daemons are built/validated):
  org.kde.kglobalaccel.service      (Exec=/usr/bin/kglobalaccel)
  org.kde.kded6.service             (Exec=/usr/bin/kded6)
  org.kde.ActivityManager.service   (Exec=/usr/bin/kactivitymanagerd)
  org.kde.JobViewServer.service     (Exec=/usr/bin/kuiserver)
  org.kde.ksmserver.service         (Exec=/usr/bin/ksmserver)

STAGED (daemons built and validated):
org.freedesktop.Notifications.service:
  [D-BUS Service]
  Name=org.freedesktop.Notifications
  Exec=/usr/bin/redbear-notifications

Recipe for Service Files

Create a redbear-dbus-services recipe that stages all activation files and policies:

local/recipes/system/redbear-dbus-services/
├── recipe.toml              # template = "custom", no source tarball
└── files/
    ├── system-services/
    │   └── org.freedesktop.login1.service
    ├── session-services/
    │   └── org.freedesktop.Notifications.service
    │   # (KDE daemon .service files removed — see §4.2/§4.3 gap analysis)
    ├── system.d/
    │   ├── org.freedesktop.login1.conf
    │   └── org.redbear.session.conf
    └── session.d/
        └── org.redbear.session.conf

6.3 D-Bus Policy Configuration

System Bus Policy (/etc/dbus-1/system.d/org.freedesktop.login1.conf)

<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
  <policy user="root">
    <allow own="org.freedesktop.login1"/>
    <allow send_destination="org.freedesktop.login1"/>
    <allow receive_sender="org.freedesktop.login1"/>
  </policy>
  <policy context="default">
    <allow send_destination="org.freedesktop.login1"
           send_interface="org.freedesktop.DBus.Introspectable"/>
    <allow send_destination="org.freedesktop.login1"
           send_interface="org.freedesktop.DBus.Properties"/>
    <allow send_destination="org.freedesktop.login1"
           send_interface="org.freedesktop.login1.Manager"/>
    <allow send_destination="org.freedesktop.login1"
           send_interface="org.freedesktop.login1.Session"/>
    <allow send_destination="org.freedesktop.login1"
           send_interface="org.freedesktop.login1.Seat"/>
    <allow receive_sender="org.freedesktop.login1"/>
  </policy>
</busconfig>

Session Bus Policy (/etc/dbus-1/session.d/org.redbear.session.conf)

<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
  <policy context="default">
    <allow own="org.kde.*"/>
    <allow send_destination="org.kde.*"/>
    <allow receive_sender="org.kde.*"/>
    <allow own="org.freedesktop.Notifications"/>
    <allow send_destination="org.freedesktop.Notifications"/>
    <allow receive_sender="org.freedesktop.Notifications"/>
  </policy>
</busconfig>

6.4 zbus Recipe

Add zbus as a recipe so it can be a build dependency for redbear-sessiond and future Rust D-Bus services:

recipes/libs/zbus/  or  local/recipes/libs/zbus/
├── recipe.toml              # cargo template
└── source/
    ├── Cargo.toml           # zbus + zvariant + zbus_names deps
    └── src/
        └── lib.rs           # (upstream zbus crate)

Note: zbus is a pure Rust crate with no C dependencies. It uses async Rust I/O (tokio or async-std) and UNIX domain sockets. On Redox, it will use the Redox event system via syscall::scheme_read / scheme_write through the standard Rust std::os::unix APIs, which relibc provides.

---

7. Phased Implementation

Phase DB-1: KWin Minimum Viable D-Bus (2–3 weeks)

Goal: KWin can start as Wayland compositor with a real session broker.

Work items:

⚠️ GROSS WARNING — DO NOT run repo cook, repo fetch, or make live directly. These bypass the canonical build pipeline (apply-patches.sh patch-linking + staleness handling + correct dependency ordering), which causes broken/missing patches and wasted rebuild time. ALWAYS build via ./local/scripts/build-redbear.sh [--upstream] <config> (or the documented make targets it drives). If you think you need a single-recipe cook, run the canonical wrapper — it does the right thing and is faster in the end.

#	Task	Acceptance Criteria
1.1	Add zbus recipe to recipe tree	make r.zbus succeeds, crate stages to sysroot
1.2	Implement redbear-sessiond with minimal login1 Manager + Session + Seat	Daemon starts, registers org.freedesktop.login1 on system bus
1.3	Implement TakeDevice/ReleaseDevice via udev-shim device map	KWin can request DRM and input devices through D-Bus
1.4	Implement TakeControl/ReleaseControl	KWin can take exclusive session ownership
1.5	Create D-Bus policy files for login1	Policy allows session compositor to call login1 methods
1.6	Create D-Bus activation .service file for login1	redbear-sessiond can be activated or init-started
1.7	Add redbear-sessiond to redbear-full.toml init services	Service starts before KWin in boot sequence
1.8	Wire XDG_SESSION_ID, XDG_SEAT, XDG_RUNTIME_DIR in the KDE session launcher	KWin sees a valid session environment
1.9	Validate: dbus-send --system --dest=org.freedesktop.login1 --print-reply /org/freedesktop/login1 org.freedesktop.login1.Manager.ListSessions	Returns non-empty session list
1.10	Validate: dbus-send --session --dest=org.kde.KWin /KWin org.kde.KWin.supportInformation	Returns non-empty KWin info string

Exit criteria:

• redbear-sessiond — binary present, service wired; runtime registration requires QEMU boot
• login1.Manager.ListSessions — implemented in sessiond; runtime validation requires QEMU
• KWin TakeDevice — DRM/input device methods structurally present; runtime requires QEMU with DRM
• KWin D-Bus registration — reduced-feature real build provides the surface; runtime proof requires Qt6Quick/QML downstream validation
• org.kde.KWin.supportInformation — structurally implemented; runtime proof requires real KWin
• Bounded compositor-session survival — validation compositor path proven; real KWin runtime proof requires Qt6Quick/QML downstream validation

Dependencies: relibc eventfd/timerfd/signalfd (already built), evdevd, udev-shim, seatd

Phase DB-2: Desktop Session Services (2–3 weeks)

Goal: plasma-workspace can start with essential session services.

Work items:

#	Task	Acceptance Criteria
2.1	Create redbear-dbus-services recipe with all session .service files	Files staged to /usr/share/dbus-1/session-services/
2.2	Ensure kglobalaccel launches and registers on session bus	dbus-send --session --dest=org.kde.kglobalaccel ... succeeds
2.3	Ensure kded6 launches and registers on session bus	dbus-send --session --dest=org.kde.kded6 ... succeeds
2.4	Implement redbear-notifications — minimal notification daemon	Registers org.freedesktop.Notifications, can receive and display a notification
2.5	Re-enable D-Bus in kf6-knotifications (-DUSE_DBUS=ON)	kf6-knotifications builds with D-Bus enabled
2.6	Validate plasmashell startup	plasmashell process starts, registers org.kde.plasmashell
2.7	Validate OSD service	org.kde.osdService responds to brightness/volume queries

Exit criteria:

• kglobalaccel — activation file staged; runtime registration requires QEMU
• kded6 — activation file staged; runtime registration requires QEMU
• org.freedesktop.Notifications — service files present; runtime Notify() requires QEMU
• kf6-knotifications — builds with D-Bus enabled (USE_DBUS=ON in recipe)
• plasmashell — plasma-workspace enabled in config; runtime registration requires full Plasma session (gated on Qt6Quick + real KWin)
• org.freedesktop.UPower — redbear-upower scaffold present; full surface requires ACPI validation beyond current bounded proof
• org.freedesktop.UDisks2 — redbear-udisks scaffold present; device enumeration requires hardware
• kf6-solid — UPower/UDisks2 backends deferred; ACPI power surface validated within bounded proof
• Shutdown signal — login1 interface structurally present; sleep signal requires ACPI sleep eventing
• org.freedesktop.PolicyKit1 — deferred; not on critical path for minimal Plasma session
• KAuth polkit backend — fake backend sufficient for bounded proof; real polkit deferred

Phase DB-5: Polish and Full Integration (ongoing)

Goal: Complete D-Bus coverage for full KDE Plasma desktop experience.

Work items:

#	Task	Acceptance Criteria
5.1	Implement org.freedesktop.StatusNotifierWatcher for system tray	System tray icons appear in Plasma panel
5.2	Implement org.kde.JobViewServer for job progress	File copy/move operations show progress in Plasma
5.3	Implement org.kde.ksmserver for session management	Logout/restart/shutdown work from Plasma menu
5.4	Implement org.freedesktop.ScreenSaver for screen locking	Screen locks on timeout and manual lock
5.5	Enable kf6-kwallet in redbear-full (recipe exists in-tree)	KWallet stores and retrieves passwords
5.6	Re-enable D-Bus in kf6-kio	KIO uses D-Bus for service activation
5.7	Promote dbus recipe from WIP to production	Remove #TODO, add BLAKE3, move from recipes/wip/services/ to recipes/services/

Dependencies: Phases DB-1 through DB-4 complete

---

8. Integration with Console-to-KDE Plan

This D-Bus plan maps directly onto the phases in CONSOLE-TO-KDE-DESKTOP-PLAN.md v4.0:

Desktop Plan Phase	D-Bus Plan Phase	What D-Bus delivers
Phase 1: Runtime Substrate Validation	(no D-Bus work — substrate is below D-Bus)	—
Phase 2: Wayland Compositor Proof	DB-1: KWin MVP	login1 session broker, system/session bus validation
Phase 3: KWin Desktop Session	DB-1 (completion) + DB-2 (session services)	kglobalaccel, kded6, notifications, plasmashell D-Bus
Phase 4: KDE Plasma Session	DB-3 (hardware services) + DB-4 (network/policy)	UPower once the ACPI power surface is honest, udisks2, NM, polkit, full session
Phase 5: Hardware GPU Enablement	(D-Bus not on critical path for GPU)	login1 TakeDevice for GPU fd passing

Modifications to Console-to-KDE Plan

The following updates should be applied to CONSOLE-TO-KDE-DESKTOP-PLAN.md:

Phase 2 — add D-Bus validation tasks:

#	Task	Acceptance Criteria
2.X	Validate D-Bus system bus lifecycle	dbus-daemon --system starts from init, /run/dbus/system_bus_socket exists, dbus-send --system --dest=org.freedesktop.DBus --print-reply /org/freedesktop/DBus org.freedesktop.DBus.ListNames returns a list including org.freedesktop.login1
2.X	Validate D-Bus session bus lifecycle	dbus-launch --sh-syntax sets DBUS_SESSION_BUS_ADDRESS, dbus-send --session --print-reply /org/freedesktop/DBus org.freedesktop.DBus.ListNames returns a non-empty list

Phase 3 — update D-Bus task 3.4:

Replace the existing task 3.4 with:

#	Task	Acceptance Criteria
3.4	Validate complete D-Bus session stack	org.freedesktop.login1.Manager.ListSessions returns valid data; org.kde.KWin.supportInformation returns non-empty string; kglobalaccel registered on session bus

Phase 4 — add D-Bus service milestone:

#	Task	Acceptance Criteria
4.X	D-Bus hardware services operational	org.freedesktop.UPower and org.freedesktop.UDisks2 register on system bus; UPower consumer claims stay bounded until the ACPI power surface is validated
4.X	D-Bus network service operational	Deferred — Red Bear OS uses redbear-netctl, not NetworkManager

---

9. D-Bus Service Dependency Map

9.1 System Bus Services

org.freedesktop.DBus (dbus-daemon itself — always present)
│
├── org.freedesktop.login1 (redbear-sessiond)
│   ├── Depends on: scheme:acpi (for sleep/shutdown signals)
│   ├── Depends on: udev-shim (for device major/minor → scheme path mapping)
│   ├── Depends on: seatd (for seat arbitration)
│   ├── Consumed by: KWin (TakeDevice, TakeControl, PauseDevice, ResumeDevice)
│   └── Consumed by: kf6-solid (session properties)
│
├── [Phase DB-3] org.freedesktop.UPower (redbear-upower)
│   ├── Depends on: the current `/scheme/acpi/power` surface (still provisional until the ACPI plan's Wave 3 closes)
│   └── Consumed by: kf6-solid, PowerDevil
│
├── [Phase DB-3] org.freedesktop.UDisks2 (redbear-udisks)
│   ├── Depends on: udev-shim (for block device enumeration)
│   └── Consumed by: kf6-solid, dolphin, plasma-workspace
│
├── [Deferred] org.freedesktop.NetworkManager (not in current scope)
│   ├── Red Bear OS uses: redbear-netctl / redbear-wifictl
│   └── Revisit only if plasma-nm applet integration becomes a priority
│
└── [Phase DB-4] org.freedesktop.PolicyKit1 (redbear-polkit)
    └── Consumed by: KAuth, privileged desktop actions

9.2 Session Bus Services

org.freedesktop.DBus (dbus-daemon — always present)
│
├── org.kde.KWin (KWin — self-registers)
│   ├── Object: /KWin
│   ├── Interfaces: org.kde.KWin, org.kde.KWin.VirtualDesktopManager
│   ├── Consumed by: plasmashell, kcm modules
│   └── Depends on: org.freedesktop.login1 (system bus)
│
├── org.kde.plasmashell (plasmashell — self-registers)
│   ├── Object: /PlasmaShell
│   ├── Interfaces: org.kde.PlasmaShell, org.kde.osdService
│   └── Consumed by: KWin (OSD calls), KDE apps
│
├── org.kde.kglobalaccel (kglobalaccel daemon)
│   ├── Activated by: .service file
│   └── Consumed by: all KDE apps (global shortcuts)
│
├── org.kde.kded6 (KDE daemon)
│   ├── Activated by: .service file
│   └── Consumed by: KDE modules (status notifier, etc.)
│
├── [Phase DB-2] org.freedesktop.Notifications (redbear-notifications)
│   ├── Activated by: .service file
│   └── Consumed by: kf6-knotifications, all KDE apps
│
├── [Phase DB-5] org.freedesktop.StatusNotifierWatcher
│   └── Consumed by: system tray, plasma panel
│
└── [Phase DB-5] org.kde.JobViewServer
    └── Consumed by: kf6-kjobwidgets, dolphin, file operations

9.3 KDE Framework D-Bus Consumer Map

KF6 Module	D-Bus Usage	Current Build Flag	Re-enable Condition
kf6-kdbusaddons	Core D-Bus wrappers	✅ Enabled	Already built
kf6-kservice	Service/plugin discovery	✅ Enabled (via kdbusaddons)	Already built
kf6-kglobalaccel	Global shortcuts via D-Bus	✅ Enabled	Needs kglobalaccel daemon running
kf6-knotifications	Desktop notifications	✅ -DUSE_DBUS=ON	Enabled against current notification scaffold; build-verified; supplementary QEMU runtime validation
kf6-solid	Hardware enumeration	⚠️ -DUSE_DBUS=OFF	Re-enable after UPower/udisks2 (DB-3)
kf6-kio	D-Bus service activation	⚠️ -DUSE_DBUS=OFF	Re-enable after core services proven (DB-3)
kf6-kwallet	Session D-Bus stable	⚠️ Not in enabled subset	Real API-only build exists in-tree (DB-5)
kf6-kauth	Privileged actions	⚠️ Fake backend	Blocked until PolkitQt6-1 is packaged and recipe switched off FAKE
kf6-kidletime	Idle detection	✅ Builds	Needs ScreenSaver D-Bus for full function
kf6-kjobwidgets	Job progress	✅ Builds	Needs JobViewServer (DB-5)

---

10. Security Model

10.1 Two-Layer Model

Layer 1: Redox Schemes (kernel-enforced capability security)
  ├── scheme:drm — only accessible to processes with explicit FD
  ├── scheme:pci — only accessible to pcid-spawner-launched drivers
  ├── scheme:input — only accessible to evdevd (which creates /dev/input/)
  └── scheme:net — only accessible to network daemons

Layer 2: D-Bus Policy (daemon-enforced access control)
  ├── System bus: XML policy files in /etc/dbus-1/system.d/
  ├── Session bus: XML policy files in /etc/dbus-1/session.d/
  └── Peer credentials: UID/GID verified via UNIX socket SCM_CREDENTIALS

Rule: Schemes are the real authority. D-Bus policy only gates who may ask a broker service to perform an operation. The broker service holds the scheme capability, not the client.

10.2 D-Bus Authentication

dbus-daemon uses the EXTERNAL SASL mechanism, which authenticates clients by their UNIX socket credentials (UID/GID via SCM_CREDENTIALS). On Redox, this requires:

1. relibc's SO_PASSCRED / SCM_CREDENTIALS support on Redox UNIX domain sockets
2. getpeereid() or equivalent — for the bus daemon to verify the connecting process's UID

Current repo status:

• relibc now exposes SO_PASSCRED, SO_PEERCRED, SCM_CREDENTIALS, and getpeereid() in the active tree
• the bounded relibc test path now covers peer-credential lookup (SO_PEERCRED) and credential delivery via recvmsg() / SCM_CREDENTIALS on Redox UNIX domain sockets

That means the supplementary D-Bus risk is no longer raw absence of the credential path in relibc; it is broader desktop/runtime trust and integration with the real bus daemons.

10.3 Policy Granularity

Keep D-Bus XML policies coarse-grained:

• Who may own a bus name (e.g., only root may own org.freedesktop.login1)
• Who may send to a destination (e.g., any user may send to org.freedesktop.login1.Manager)
• Who may receive from a sender (e.g., any user may receive signals from login1)

Keep fine-grained authorization inside the Rust service:

• redbear-sessiond checks whether the requesting process's UID matches the active session owner
• redbear-sessiond checks whether the requesting process is the compositor before granting TakeControl()
• redbear-polkit checks at-console status before authorizing privileged actions

Do NOT try to map every scheme permission into D-Bus XML policy.

10.4 Session Bus Isolation

The session bus must only be accessible to the owning user:

• DBUS_SESSION_BUS_ADDRESS should point to a socket in XDG_RUNTIME_DIR (e.g., /tmp/run/user/0/)
• Socket permissions must be 0600 (owner-only)
• No TCP transport — UNIX sockets only (TCP is deprecated in D-Bus anyway)

---

11. Build Recipe Changes

11.1 New Recipes

Recipe	Location	Template	Dependencies
zbus	local/recipes/libs/zbus/	custom (build-ordering marker)	none
redbear-sessiond	local/recipes/system/redbear-sessiond/	cargo	zbus, libredox, redox-syscall
redbear-dbus-services	local/recipes/system/redbear-dbus-services/	custom	dbus (for staging dirs)
redbear-notifications	local/recipes/system/redbear-notifications/	cargo	zbus
redbear-upower	local/recipes/system/redbear-upower/	cargo	zbus
redbear-udisks	local/recipes/system/redbear-udisks/	cargo	zbus
redbear-polkit	local/recipes/system/redbear-polkit/	cargo	zbus

Note: redbear-nm (NetworkManager facade) is NOT in scope. Red Bear OS uses its native redbear-netctl for network management. NM may be revisited if a future KDE Plasma NM applet integration is needed.

11.2 Modified Recipes

Recipe	Change	Phase
dbus	Promote from WIP, add runtime validation	DB-5
kf6-knotifications	Change -DUSE_DBUS=OFF → -DUSE_DBUS=ON	DB-2 ✅ done
kf6-solid	Change -DUSE_DBUS=OFF → -DUSE_DBUS=ON, re-enable UPower backend	DB-3
kf6-kio	Change -DUSE_DBUS=OFF → -DUSE_DBUS=ON	DB-5
kf6-kwallet	Enable in config (recipe exists in-tree)	DB-5
qtbase (host)	Consider enabling FEATURE_dbus=ON for host tools (qdbuscpp2xml/qdbusxml2cpp)	DB-2

11.3 Config Changes

redbear-full.toml additions:

[packages]
# D-Bus session/seat broker
redbear-sessiond = {}
redbear-dbus-services = {}

# [[files]] — redbear-sessiond init service
[[files]]
path = "/usr/lib/init.d/13_redbear-sessiond.service"
data = """
[unit]
description = "Red Bear session broker (login1)"
requires_weak = [
    "12_dbus.service",
]

[service]
cmd = "redbear-sessiond"
type = "oneshot_async"
"""

KDE session launcher updates:

# After dbus-launch, set session variables
export XDG_SESSION_ID=c1        # redbear-sessiond session ID
export XDG_SEAT=seat0
export XDG_SESSION_TYPE=wayland
export XDG_RUNTIME_DIR=/tmp/run/user/0
export XDG_CURRENT_DESKTOP=KDE

# Ensure session bus environment is in D-Bus activation environment
dbus-update-activation-environment \
    WAYLAND_DISPLAY \
    XDG_SESSION_ID \
    XDG_SEAT \
    XDG_SESSION_TYPE \
    XDG_RUNTIME_DIR \
    XDG_CURRENT_DESKTOP \
    KDE_FULL_SESSION \
    DISPLAY

---

12. Testing and Validation

12.1 Phase DB-1 Tests

# System bus basic
dbus-send --system --dest=org.freedesktop.DBus --print-reply \
    /org/freedesktop/DBus org.freedesktop.DBus.ListNames

# login1 presence
dbus-send --system --dest=org.freedesktop.login1 --print-reply \
    /org/freedesktop/login1 org.freedesktop.login1.Manager.ListSessions

# login1 seat
dbus-send --system --dest=org.freedesktop.login1 --print-reply \
    /org/freedesktop/login1/seat/seat0 org.freedesktop.DBus.Properties.GetAll \
    string:"org.freedesktop.login1.Seat"

# Session bus basic
dbus-send --session --dest=org.freedesktop.DBus --print-reply \
    /org/freedesktop/DBus org.freedesktop.DBus.ListNames

# KWin registration (after KWin starts)
dbus-send --session --dest=org.kde.KWin --print-reply \
    /KWin org.kde.KWin.supportInformation

12.2 Phase DB-2 Tests

# kglobalaccel
dbus-send --session --dest=org.kde.kglobalaccel --print-reply \
    /kglobalaccel org.freedesktop.DBus.Introspectable.Introspect

# kded6
dbus-send --session --dest=org.kde.kded6 --print-reply \
    /kded org.freedesktop.DBus.Introspectable.Introspect

# Notifications
dbus-send --session --dest=org.freedesktop.Notifications --print-reply \
    /org/freedesktop/Notifications org.freedesktop.Notifications.Notify \
    string:"test" uint32:0 string:"" string:"Test" string:"Body" array:string:{} dict:string:string:{} int32:5000

# plasmashell
dbus-send --session --dest=org.kde.plasmashell --print-reply \
    /PlasmaShell org.freedesktop.DBus.Introspectable.Introspect

12.3 QEMU Validation Script

Create local/scripts/test-dbus-qemu.sh:

#!/bin/sh
# Validates D-Bus stack in QEMU-booted Red Bear OS
# Usage: ./local/scripts/test-dbus-qemu.sh --check

echo "=== D-Bus System Bus ==="
echo "System bus socket:"
ls -la /run/dbus/system_bus_socket 2>&1

echo "Bus names:"
dbus-send --system --dest=org.freedesktop.DBus --print-reply \
    /org/freedesktop/DBus org.freedesktop.DBus.ListNames 2>&1

echo "login1 sessions:"
dbus-send --system --dest=org.freedesktop.login1 --print-reply \
    /org/freedesktop/login1 org.freedesktop.login1.Manager.ListSessions 2>&1

echo ""
echo "=== D-Bus Session Bus ==="
echo "Session bus address:"
echo "$DBUS_SESSION_BUS_ADDRESS"

echo "Session bus names:"
dbus-send --session --dest=org.freedesktop.DBus --print-reply \
    /org/freedesktop/DBus org.freedesktop.DBus.ListNames 2>&1

---

13. Risks and Mitigations

13.1 Technical Risks

Risk	Impact	Likelihood	Mitigation
UNIX socket credential passing regresses on Redox	D-Bus authentication fails	Medium	Keep the relibc UDS credential tests in the preserved proof path; if broken again, fall back to cookie auth or patch relibc
KWin login1 expectations exceed our minimal subset	KWin crashes or refuses to start	Medium	Start with KWin's Noop fallback; add methods incrementally as KWin logs errors
zbus async runtime conflicts with Redox event system	zbus doesn't build or run	Low	zbus supports multiple async runtimes; test tokio + Redox early
D-Bus service activation files not picked up by dbus-daemon	Services must be started manually	Low	dbus-daemon 1.16.2 supports classic activation; verify search path in redox.patch
Device major/minor mapping unstable	TakeDevice returns wrong device	Medium	Use udev-shim as single source of truth; add validation tests
PAM not available for elogind-like session tracking	Cannot use elogind directly	Certain	That's why we're building redbear-sessiond — no PAM dependency
Peer credential path behaves differently under real dbus-daemon load	System bus policy can't verify UIDs reliably	Medium	The relibc credential path is now present and bounded-tested; next tighten with real dbus-daemon/session-bus runtime validation

13.2 Integration Risks

Risk	Impact	Mitigation
KDE Plasma 6 accumulates more systemd assumptions	More D-Bus services needed than anticipated	Monitor KDE Plasma releases; test each upgrade
Re-enabling D-Bus in kf6 components exposes build failures	Build breakage in previously-stable recipes	Re-enable one component at a time, with CI gating
Init service ordering conflicts	redbear-sessiond starts before dbus-daemon	Use requires_weak = ["12_dbus.service"] in init config

13.3 Escalation Triggers

• If TakeDevice() cannot be made to work via major/minor → scheme path mapping: Add a small Redox-only KWin session backend that talks to the native seat/device broker directly (bypasses D-Bus for device access). Keep the rest of the D-Bus architecture unchanged.

• If zbus cannot build on Redox (async runtime incompatibility): Fall back to libdbus-1 C bindings for Rust services (via the dbus crate). Less ergonomic but proven to work with the existing dbus build.

• If KDE hard-requires more freedesktop services than expected: Add them as individual compatibility daemons, not a generic bridge. Each daemon wraps exactly one freedesktop contract.

---

14. Qt 6.11 D-Bus Coverage

This appendix closes an important scoping gap in the plan. Qt 6.11 itself already carries D-Bus coverage for the Redox target, and the KDE build stack already has a working code generation path for D-Bus XML tooling during cross-compilation. The missing pieces are higher-level freedesktop service contracts and the staged re-enablement of KF6 components that were intentionally built with D-Bus disabled.

14.1 Qt Build Configuration

The current Qt 6.11 setup splits D-Bus support differently between target and host builds.

Target build (qtbase for Redox):

• -DFEATURE_dbus=ON (line 419 of recipe.toml)
• "dbus" listed as build dependency (line 16)
• Qt6DBus module built and staged
• libQt6DBus.so.6.11.0 staged to sysroot

Host build (qtbase-host):

• -DFEATURE_dbus=OFF (line 104)
• Profile name: qtbase-host-6.11.0-gui-xml-wayland-no-qdbus-host (line 63)
• qdbuscpp2xml and qdbusxml2cpp subdirectories disabled via Python patching (lines 71-74)
• These tools are needed at BUILD time by kf6-kdbusaddons, kwin, kf6-kio for D-Bus XML → C++ code generation

The practical result is that QtDBus support exists in the target sysroot today. Build-time D-Bus tooling for host-side code generation is the only area still running through a workaround path.

14.2 qdbuscpp2xml/qdbusxml2cpp Provisioning

The current provisioning strategy is intentionally pragmatic.

Since the host build disables D-Bus, KDE recipes provision these tools via symlinks:

• kf6-kdbusaddons (lines 22-32): First tries ${HOST_BUILD}/libexec/$tool, then falls back to /usr/bin/qdbuscpp2xml and /usr/bin/qdbusxml2cpp from the host system
• kwin (line 67): for tool in moc rcc uic qdbuscpp2xml qdbusxml2cpp wayland-scanner; do
• kf6-kio (line 33): Same pattern as kwin

The host system packages provide these tools during cross-compilation. This is a pragmatic workaround, not a long-term solution. Future improvement: enable FEATURE_dbus=ON in the host build once D-Bus session bus validation passes on the host toolchain.

14.3 KF6 Components with D-Bus Disabled

The following KF6 components currently build with -DUSE_DBUS=OFF. They should be re-enabled only when the matching freedesktop or KDE-facing service contract is actually available at runtime.

Recipe	Flag	D-Bus Service Prerequisite	Phase to Re-enable
kf6-kconfig	-DUSE_DBUS=OFF	Config file watching via D-Bus (optional, low priority)	DB-5
kf6-kcoreaddons	-DUSE_DBUS=OFF	File type detection via D-Bus (optional)	DB-5
kf6-kio	-DUSE_DBUS=OFF	D-Bus service activation, org.kde.KIO::*	DB-5
kf6-knotifications	-DUSE_DBUS=ON	org.freedesktop.Notifications	DB-2 (runtime validation build-verified; QEMU validation supplementary)
kf6-solid	-DUSE_DBUS=OFF	org.freedesktop.UPower + org.freedesktop.UDisks2 + org.freedesktop.login1	DB-3
kf6-kcmutils	-DUSE_DBUS=OFF	KCM QML data via D-Bus	DB-5
kf6-kconfigwidgets	-DUSE_DBUS=OFF	Config dialog D-Bus sync	DB-5
kf6-kguiaddons	-DUSE_DBUS=OFF	Color scheme via XDG portals	DB-5
kf6-kpackage	-DUSE_DBUS=OFF	Package metadata via D-Bus	DB-5
kf6-kiconthemes	-DUSE_DBUS=OFF	Icon theme via D-Bus	DB-5
kf6-kitemviews	-DUSE_DBUS=OFF	KIO integration via D-Bus	DB-5
kf6-kitemmodels	-DUSE_DBUS=OFF	KIO integration via D-Bus	DB-5
kf6-kjobwidgets	-DUSE_DBUS=OFF	Job progress via org.kde.JobViewServer	DB-5
kirigami	-DUSE_DBUS=OFF	Cross-device sharing	DB-5
plasma-framework	-DUSE_DBUS=OFF	Plasma widget D-Bus integration	DB-5

14.4 Re-enablement Priority Order

Re-enablement must follow service availability, not package build order.

1. DB-1 (now): redbear-sessiond provides org.freedesktop.login1 → kf6-solid UPower backend can connect (but needs UPower daemon too)
2. DB-2: redbear-notifications provides org.freedesktop.Notifications → re-enable kf6-knotifications
3. DB-3: redbear-upower provides org.freedesktop.UPower → re-enable kf6-solid (with UPower backend)
4. DB-4: redbear-udisks provides org.freedesktop.UDisks2 → kf6-solid UDisks2 backend
5. DB-5: Full desktop services → re-enable kf6-kio, kf6-kjobwidgets, kf6-kcmutils, and all supplementary components

The key insight: QtDBus is NOT the gap. Qt6DBus builds and kf6-kdbusaddons provides the convenience layer. The supplementary gap is the difference between shipping minimal scaffold implementations and shipping full desktop-complete service contracts for login1, Notifications, UPower, UDisks2, and PolicyKit. NetworkManager remains deferred and is not part of the current Red Bear OS implementation scope.

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Phase 3/4 D-Bus Improvement Plan (2026-04-25 Assessment)

Assessment scope: All Red Bear D-Bus service implementations (redbear-sessiond, redbear-notifications, redbear-upower, redbear-udisks, redbear-polkit), plus the dbus-daemon itself, conducted via 4 parallel evaluation agents (Oracle + 2 explore + librarian).

Key finding: Phase 2 (kwin_wayland --virtual) should work without D-Bus changes. KWin falls back to NoopSession when logind is unavailable, and the Noop backend bypasses login1 entirely.

Key finding: Phase 3 has one hard gate: TakeDevice FD passing. This cannot be bypassed.

Assessment Summary

Fragility ratings across services:

Service	Rating	Primary concern
redbear-sessiond	5/5	login1 is the critical path for DRM compositor
redbear-polkit	5/5 security	Always-permit is not a production security model
dbus-daemon	2/5	24-line patch is stable but not validated under real session bus load
redbear-notifications	2-3/5	Logs to stderr only; no ActionInvoked signal
redbear-upower	2-3/5	Provisional ACPI surface; no Changed signal; polling deferred (requires QEMU validation)
redbear-udisks	2-3/5	Read-only; no mount/unmount operations

Phase 2 assessment: D-Bus is NOT on the critical path for kwin_wayland --virtual. The NoopSession backend in KWin bypasses logind entirely, which means Phase 2 compositor bring-up should succeed without D-Bus changes.

Phase 3 hard gate: TakeDevice FD passing + PauseDevice/ResumeDevice signal emission. This is required for KWin to own real DRM and input devices through the freedesktop session protocol. No bypass exists.

Phase 4 broader surface: kglobalaccel binary, kded6 binary, StatusNotifierWatcher, Inhibit methods, session identity derivation.

Phase 3 Gate (DRM Compositor) — Required D-Bus Changes

Four fixes are required before KWin can use real hardware devices through login1:

#	Fix	Current state	Required change
1	Manager.Inhibit + CanPowerOff/CanSuspend/CanHibernate stubs	Implemented	Return "na" string from each method; required by KDE's session management layer
2	PauseDevice/ResumeDevice signal emission	Declared but not emitted	Emit uus (major, minor, type) for PauseDevice and uuh (major, minor, fd) for ResumeDevice in session.rs when device state changes
3	Dynamic device enumeration	Static device_map.rs with hardcoded major/minor	Query udev-shim at runtime for major/minor -> scheme path mapping; remove hardcoded lookup table
4	Session methods	SetIdleHint, SetLockedHint, SetType, Terminate return errors; runtime validation requires QEMU

Phase 4 Gate (KDE Plasma Session) — Required D-Bus Changes

#	Improvement	Current state	Required change
1	`StatusNotifierWatcher: activation file staged	Register org.freedesktop.StatusNotifierWatcher on session bus; track registered items, emit ItemRegistered/ItemUnregistered signals
2	kglobalaccel binary build	KDE app recipe builds library, daemon binary is a separate recipe step	Add kglobalaccel binary to local/recipes/kde/kf6-kglobalaccel/ or create separate recipe
3	kded6 binary build	KDE app recipe builds library, daemon binary is a separate recipe step	Add kded6 binary to local/recipes/kde/kf6-kded6/ or create separate recipe
4	Session identity derivation	Hardcoded to c1, root, uid=0	Query real session environment variables (XDG_SESSION_ID, XDG_SEAT) and derive identity from the actual login session
5	UPower Changed signal emission + polling	No signals, no polling	Emit Changed signal when power state changes; implement property polling for OnBattery, Percentage, TimeToEmpty
6	Notifications ActionInvoked signal + capabilities	Activation file staged; runtime deferred	Emit ActionInvoked(uint32, string) when user clicks notification action; expand GetCapabilities to include body, actions, icon-static
7	Stoppable daemons	Services use supplementary() with no shutdown channel	Replace supplementary() in all services with proper shutdown signal channels; enable service restart and clean shutdown

KWin Method-by-Method Readiness Matrix

KWin D-Bus call	Current impl	Phase 2 needed	Phase 3 needed
GetSession("auto")	via NoopSession	No (bypasses logind)	Yes
TakeControl(false)	Via login1	No	Yes
TakeDevice(226, 0) (DRM)	Via DeviceMap	No	Yes (critical)
TakeDevice(13, 64+) (input)	Via DeviceMap	No	Yes (critical)
PauseDevice signal	Declared, not emitted	No	Yes (critical)
ResumeDevice signal	Declared, not emitted	No	Yes (critical)
Seat.SwitchTo	Via login1	No	Yes
Manager.Inhibit	Implemented	No	Yes
CanPowerOff/CanSuspend/CanHibernate	Implemented	No	Yes
PrepareForShutdown	Via ACPI	No	Yes
PrepareForSleep	Declared, not emitted	No	Yes

Completeness by Service

Service	Methods real	Total expected	Completeness
login1.Manager	3	~30+	~10%
login1.Session	7	~15+	~47%
login1.Seat	1	5	~20%
Notifications	4	~5	~80%
UPower	3	~5	~60%
UDisks2	4	~8+	~50%
PolicyKit1	3	~6+	~50%

Implemented KDE D-Bus Services

Service	Used by	Status	Impact
org.kde.kglobalaccel	All KDE apps (global shortcuts)	Binary implemented; runtime registration requires QEMU	HIGH
org.kde.kded6	KDE daemon (status notifier, etc.)	Binary implemented; runtime registration requires QEMU	HIGH
`org.freedesktop.StatusNotifierWatcher: activation file staged	MEDIUM
`org.kde.ksmserver: activation file staged	MEDIUM
org.freedesktop.ScreenSaver	Screen locking	Activation file staged; runtime deferred	MEDIUM

Implementation Priority Order

1. redbear-sessiond Phase 3 methods (enables DRM compositor session)
2. Dynamic device enumeration (enables non-static hardware discovery)
3. Stoppable daemons (enables testing and restart)
4. StatusNotifierWatcher (enables system tray)
5. UPower polling + signals (enables battery applet)
6. Session identity improvements (enables non-root sessions)