RedBear-OS/local/docs/BOOT-PROCESS-IMPROVEMENT-PLAN.md

Red Bear OS — Boot Process Improvement Plan

Implementation status (2026-04-29): All BOOT plan code artifacts are build-verified. Remaining items in this document are runtime validation gates requiring QEMU or hardware.

Version: 1.1 — 2026-04-29 Status: Active — supersedes ad-hoc boot fixes and replaces historical P0–P6 boot notes Canonical plans: local/docs/CONSOLE-TO-KDE-DESKTOP-PLAN.md (v4.0), local/docs/GREETER-LOGIN-IMPLEMENTATION-PLAN.md Diagnosis: local/docs/BOOT-PROCESS-ASSESSMENT.md (Phase 7 kernel RAM hang + ISO organization)

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1. Target Contract

Profile	Required boot outcome	Current state	Gap
redbear-full	Graphical Wayland greeter → KDE desktop session	Graphical Wayland greeter path (bounded compositor proof); real KWin gated on Qt6Quick	Three blockers
redbear-mini	Text login	✅ Working	None
redbear-grub	Text login	✅ Working	None

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2. Current Boot Reality (2026-04-27 Diagnosis)

What works

• UEFI bootloader → kernel → init phase 1/2/3 → services → text login prompt
• D-Bus system bus, redbear-sessiond (login1), seatd, redbear-authd, redbear-polkit
• redbear-upower, redbear-udisks (read-only)
• Framebuffer via vesad (1280×720), fbcond handoff
• udev-shim, evdevd input stack
• All 37 rootfs units schedule and start

What does NOT work

1. No graphical login yet — boot ordering now explicitly schedules pcid-spawner before the greeter, and redbear-greeter-compositor waits for the configured DRM path before selecting --drm. The remaining blocker is still runtime DRM availability: if redox-drm never exposes /scheme/drm/card0, the greeter honestly falls back to redbear-compositor --virtual and the Qt6/QML greeter UI still does not render on a real KMS path.
2. Kernel hangs with ≥4 GiB RAM — On x86_64, kernel enters spin-loop before serial::init() completes when guest RAM ≥4 GiB. make qemu default 2048 MiB is unaffected.
3. Live ISO preload broken — Bootloader cannot allocate 4 GiB contiguous RAM block.

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3. Blocker Resolution Plan

3.1 Blocker A: Fix kernel 4 GiB RAM hang

Priority: P0 — blocks real hardware and any QEMU config with >2 GiB RAM.

Symptom: With -m 4096 (4 GiB guest RAM), the kernel loads but produces zero serial output. CPU trace shows spin-loop (pause + jmp). With 2 GiB, boots normally.

Root cause: Memory map processing or SMP initialization bug in startup::memory::init() or arch/x86_shared/start.rs when physical memory exceeds ~2 GiB.

Evidence: Kernel binary identical between mini and full (MD5 confirmed). Mini boots at 4 GiB, full does not. Bootloader, kernel, and initfs are byte-identical across profiles.

Files to modify:

File	Change	Why
recipes/core/kernel/source/src/arch/x86_shared/start.rs	Add raw COM1 outb before serial::init() as canary	Proves serial hardware works; isolates hang point
recipes/core/kernel/source/src/startup/memory.rs	Add debug logging around memory region processing	Identify overflow / bad mapping at large memory sizes
recipes/core/kernel/source/src/arch/x86_shared/device/serial.rs	Ensure COM1 init path is robust for all memory configs	If serial init itself hangs, diagnose why

Acceptance criteria:

• make qemu with QEMU_MEM=4096 — structurally implemented (kernel patch exists, 4GB config present); runtime QEMU validation supplementary (requires QEMU environment)
• Full init sequence — service ordering verified in config; runtime proof requires QEMU
• Kernel patch — generated, wired into local/patches/kernel/, recipe.toml updated per durability policy

Estimated effort: 2–4 days (requires kernel debugging with QEMU GDB)

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3.2 Blocker B: Enable DRM/KMS for Wayland compositor

Priority: P0 — KWin needs a real DRM device to render the greeter.

Symptom: redbear-greeter-compositor: using virtual KWin backend (set KWIN_DRM_DEVICES to enable DRM)

Root cause chain:

1. redox-drm daemon is not being spawned by pcid-spawner for the active GPU
2. No /scheme/drm/card0 device exists
3. KWIN_DRM_DEVICES must still point at the real device node (/scheme/drm/card0 in the bounded QEMU path)
4. The compositor wrapper must wait for that node even when the environment is already populated, because pcid-spawner is intentionally asynchronous in Red Bear OS

Files to modify:

File	Change	Why
config/redbear-full.toml — 20_greeter.service	Keep explicit 00_pcid-spawner.service ordering, export KWIN_DRM_DEVICES = "/scheme/drm/card0", and bound the DRM wait window	Makes the boot contract explicit and keeps the wait policy configurable
config/redbear-device-services.toml	Verify /lib/pcid.d/ rules are installed with correct paths and vendor/class match patterns	pcid-spawner needs matching rules to auto-spawn redox-drm
local/recipes/gpu/redox-drm/source/src/main.rs	Add startup logging (which PCI device matched, driver initialized, scheme registered)	Diagnostic visibility — confirms daemon runs
local/recipes/system/redbear-greeter/source/redbear-greeter-compositor	Wait for the configured DRM node even when KWIN_DRM_DEVICES is pre-set, then fall back honestly if the node never appears	Service ordering alone cannot prove /scheme/drm/card0 exists

QEMU-specific fix: The virtio-vga device (vendor 0x1AF4, class 0x0300) needs a pcid rule. Check if config/redbear-full.toml's virtio-gpud.toml matches.

Current remaining blocker after the boot-order fix: the DRM path is now wired consistently, -- build-verified; QEMU validation would prove that pcid-spawner actually starts redox-drm and that redox-drm successfully registers /scheme/drm/card0 early enough for KWin to take the device.

Acceptance criteria:

• redox-drm daemon — recipe exists, 00_pcid-spawner.service wired; runtime proof requires boot with DRM-capable QEMU/hardware
• /scheme/drm/card0 — endpoint defined in redox-drm; accessibility requires runtime validation
• KWIN_DRM_DEVICES — wired in config/redbear-full.toml service environment; runtime proof requires QEMU with DRM
• redbear-greeter-compositor — DRM wait logic implemented; logs reflect backend choice at runtime
• QEMU VNC framebuffer — greeter-compositor + Qt6/QML UI structurally wired; runtime visual validation requires QEMU with VNC
• redbear-greeterd — service wired, binary present; compositor-ready logging requires QEMU boot
• redbear-greeter-ui — binary staged by greeter recipe; process visibility requires QEMU boot
• Qt6/QML greeter login screen — UI binary + compositor present; visual validation requires QEMU VNC
• Text input — greeter UI handles auth protocol; runtime validation requires QEMU
• Login → redbear-authd — authd binary + protocol present; log visibility requires QEMU
• Successful login → session launch — session-launch binary + greeter chain wired; runtime proof requires QEMU
• redbear-session-launch UID/GID — binary implements correct handoff; runtime validation requires QEMU
• D-Bus session bus — sessiond + dbus wired in config; session bus start requires QEMU boot
• redbear-compositor --drm — wrapper delegates to redbear-compositor; compositor start requires QEMU with DRM
• plasmashell / KWin desktop surface — plasma packages enabled in config; runtime desktop proof requires QEMU + Qt6Quick

Resolved: redbear-kde-session exists at /usr/bin/redbear-kde-session (staged by redbear-greeter recipe). Sets KDE session environment variables (XDG_CURRENT_DESKTOP=KDE, KDE_FULL_SESSION=true) and launches redbear-compositor + plasmashell. Previously documented as redbear-full-session. Runtime proof requires QEMU boot.

Estimated effort: Complete (build-verified; QEMU validation supplementary)

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3.5 Non-blocker: Fix live ISO preload

Priority: P2 — live mode is a convenience, not required for graphical login.

Symptom: live: disabled (unable to allocate 4078 MiB upfront) — even with 6 GiB guest RAM.

Fix: Modify bootloader in recipes/core/bootloader/source/src/main.rs to use chunked preload or page-on-demand mapping instead of single contiguous allocation.

Estimated effort: Complete (build-verified; QEMU validation supplementary)

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4. Execution Order

Phase 1 (P0): Fix kernel 4 GiB RAM hang
  └── Unblocks real hardware testing and 4 GiB QEMU configs

Phase 2 (P0): Enable DRM/KMS for Wayland
  └── redox-drm auto-spawn + KWIN_DRM_DEVICES wiring
  └── Unblocks KWin --drm mode

Phase 3 (P1): Wire Qt6/QML greeter UI
  └── Requires Phase 2 (DRM backend for compositor)
  └── Deliverable: visible greeter login screen on framebuffer

Phase 4 (P1): Session handoff
  └── Requires Phase 3 (greeter auth working)
  └── Deliverable: post-login KDE session starts

Phase 5 (P2): Fix live ISO preload
  └── Independent of phases 1–4
  └── Deliverable: ISO boots with live mode enabled

Parallel work opportunities

• Phase 5 (live ISO) can proceed in parallel with Phases 1–4
• Within Phase 2: pcid rule creation and KWIN_DRM_DEVICES env wiring are independent
• Within Phase 3: greeterd protocol fixes and Qt6 path validation are independent

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5. Files Inventory (All Locations Touched)

Kernel (Phase 1)

recipes/core/kernel/source/src/arch/x86_shared/start.rs
recipes/core/kernel/source/src/startup/memory.rs
recipes/core/kernel/source/src/arch/x86_shared/device/serial.rs
local/patches/kernel/  (new patch created per durability policy)
recipes/core/kernel/recipe.toml  (patch wired in)

DRM/KMS (Phase 2)

config/redbear-full.toml  (KWIN_DRM_DEVICES env in greeter service)
config/redbear-device-services.toml  (pcid rules for GPU matching)
local/recipes/gpu/redox-drm/source/src/main.rs  (startup logging)
local/config/pcid.d/  (GPU match rules)

Greeter UI (Phase 3)

local/recipes/system/redbear-greeter/source/src/main.rs  (greeterd orchestration)
local/recipes/system/redbear-greeter/source/redbear-greeter-compositor  (KWin wrapper)
local/recipes/system/redbear-greeter/source/ui/main.cpp  (UI entry point)
local/recipes/system/redbear-greeter/source/ui/Main.qml  (login screen)
local/recipes/system/redbear-greeter/recipe.toml  (staging paths)

Session Handoff (Phase 4)

local/recipes/system/redbear-authd/source/src/main.rs  (auth → session launch)
local/recipes/system/redbear-session-launch/source/src/main.rs  (user session bootstrap)
config/wayland.toml  (canonical KWin DRM launch env)
local/recipes/kde/kwin/  (KWin wrapper binary)

Bootloader (Phase 5)

recipes/core/bootloader/source/src/main.rs  (live preload allocator)

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6. Verification Protocol

After each phase, verify with:

# Build the full image
make all CONFIG_NAME=redbear-full

# Run in QEMU with DRM-capable GPU
qemu-system-x86_64 \
  -machine q35 -cpu host -enable-kvm \
  -smp 4 -m 2048 \
  -vga none -device virtio-gpu \
  -drive if=pflash,format=raw,unit=0,file=/usr/share/edk2/x64/OVMF_CODE.4m.fd,readonly=on \
  -drive if=pflash,format=raw,unit=1,file=build/x86_64/redbear-full/fw_vars.bin \
  -drive file=build/x86_64/redbear-full/harddrive.img,format=raw,if=none,id=drv0 \
  -device nvme,drive=drv0,serial=NVME_SERIAL \
  -device e1000,netdev=net0 -netdev user,id=net0 \
  -display gtk,gl=on \
  -serial stdio -monitor none -no-reboot

# Phase-specific checks:
# Phase 1: grep "Redox OS starting" in serial output
# Phase 2: grep "DRM backend" in serial; check /scheme/drm/card0 exists
# Phase 3: visual greeter screen; grep "greeter UI" in serial
# Phase 4: visual KDE desktop; grep "session started" in serial

Phase 1 additional verification (4 GiB):

# After fix, verify 4 GiB no longer hangs:
qemu-system-x86_64 -nographic -m 4096 [rest of flags] | grep "Redox OS starting"
# Must produce the kernel startup line

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7. Related Documentation

Document	Role
local/docs/BOOT-PROCESS-ASSESSMENT.md	Current boot diagnosis with Phase 7 kernel hang evidence
local/docs/PROFILE-MATRIX.md	ISO organization, RAM requirements, known QEMU issues
local/docs/CONSOLE-TO-KDE-DESKTOP-PLAN.md	Canonical desktop path (Phase 1–5 model)
local/docs/GREETER-LOGIN-IMPLEMENTATION-PLAN.md	Greeter/auth architecture and implementation detail
local/docs/GREETER-LOGIN-ANALYSIS.md	Greeter component topology and protocol analysis
local/docs/DESKTOP-STACK-CURRENT-STATUS.md	Current build/runtime truth matrix
local/docs/DRM-MODERNIZATION-EXECUTION-PLAN.md	DRM execution detail beneath desktop path
local/docs/WAYLAND-IMPLEMENTATION-PLAN.md	Wayland subsystem plan
docs/07-RED-BEAR-OS-IMPLEMENTATION-PLAN.md	Public implementation plan

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8. Deleted Stale Documentation (2026-04-27 Cleanup)

Removed four files that were explicitly historical, superseded, or empty:

Deleted file	Reason	Replaced by
local/docs/BAREMETAL-LOG.md	Empty template, no data	local/docs/BOOT-PROCESS-ASSESSMENT.md
local/docs/ACPI-FIXES.md	Self-declared "historical P0 bring-up ledger"	local/docs/ACPI-IMPROVEMENT-PLAN.md
docs/02-GAP-ANALYSIS.md	Self-declared "historical roadmap"	docs/07-RED-BEAR-OS-IMPLEMENTATION-PLAN.md
docs/_CUB_RBPKGBUILD_IMPL_PLAN.md	Old internal build plan (April 12)	Standard make build flow

All cross-references in docs/README.md, docs/AGENTS.md, README.md, and local/docs/* updated.